What is the meaning of "matter" in physics?

Question: What is the meaning of matter in physics?  By defining matter in terms of mass and mass in terms of matter in physics, are we not forming circular definitions? Please give a meaning of "matter" in Physics that circumvents this circularity.
Comment: what is the context? For what particular experiment are you asking this?
Comment: This is very google-able. For example, https://en.wikipedia.org/wiki/Matter
Comment: Could these be of interest? https://en.wikipedia.org/wiki/Quantum_chromodynamics_binding_energy and https://en.wikipedia.org/wiki/Higgs_boson#Particle_mass_acquisition
Comment: Mass is not defined in terms of matter in physics (it is defined, roughly, as the energy remaining when something is not moving), so no need to worry about circularity.
Comment: Mass can be defined gravitationally or inertially, and while no *measurement* has yet demonstrated a difference between the two, I'm not aware that current theories *require* them to be equal.
Comment: @chepner - there is Einstein's equivalence principle, though; whether it is really fundamentally important for the theory, I don't recall; it's been too long since I studied it.
Comment: You run into the same problem in the definition of all fundamental things. Try length for instance. Or time. Their definitions ultimately rely on us having experienced this universe. Then, we expand on these quite a bit.
Answer:
What is the meaning of "matter" in physics?

It doesn't matter. Sometimes matter means "particles with rest mass". Sometimes matter means "anything that contributes to the stress-energy tensor". Sometimes matter means "anything made of fermions". And so on. There's no need to have one official definition of the word "matter", nothing about the physical theories depends on what we call the words.
Discussing this any further is just like worrying about whether a tomato is really a fruit or a vegetable. A cook doesn't care.
Comment: "Knowledge is knowing a tomato is a fruit.  Wisdom is knowing not to put tomato into fruit salad."
Comment: +1 Definitely agree with the way you answered the way you interpreted the question, but a more interesting interpretation is: what gives matter mass? This question seems much more fundamental and meaningful to me.
Comment: @JoeIddon not to disregard your curiosity, but that is what 10000 scientists at CERN are figuring out
Comment: @aaaaaa Not really. Just because something gives mass to electrons doesn't mean it also gives mass to protons (and we're pretty sure they're completely unrelated, beyond the general "mass is just the energy of a system").
Comment: @JoeIddon then you should ask your own question.
Comment: @Luaan CERN scientist certainly do investigate both of those processes. And much more.
Comment: @CortAmmon When I put tomatoes in a fruit salad, they are the only ingredient.
Answer:
Please give a meaning of "matter" in Physics that circumvents this
  circularity.

In modern physics, mass is definitely not defined in terms of matter, and there is no circularity.
What we classically called mass was really a definition of its effects on and by other objects. We saw this as an intrinsic quality of an object, and definitional in that statement is that different types of matter had different masses - a 1m sphere of steel is more massive than a 1m sphere of water. We saw that as "obvious", different types of matter have different amounts of mass and that just makes sense.
Critically, the mass of an object defined its gravitational effect. That is, gravity was something caused by mass. This made mass "a thing", and objects with mass were "matter". Compare this to, for instance, a water wave. This clearly exists but is not of itself material, it's simply the water that was already there moving up and down. A body of water would cause a certain amount of gravity, and adding waves, which are "non-material", would not change that.
With the introduction of General Relativity in the early 20th century, this definition was seen to be incorrect. Earlier, Einstein concluded that E=mc^2, which means that mass is (although this terminology is very misleading) "another form of energy". Pondering this, a number of contemporary physicists helped develop GR, in which any and all energy causes gravity (though a mathematically complex system). So in GR, adding waves to water does increase its gravity, because the system has more energy. A shotput will have a certain gravity, and that will change if you heat it. Etc.
At this point, the link between mass and matter was broken. Mass was previously "that thing that causes gravity", but in GR, that was gone. Matter was previously "those things with mass", and while one could change that to be "rest mass" and still have a reasonable definition, we no longer needed it, there is no real need to have a definition of matter.
This is not a theoretical issue - it one "weights" an electron it will have higher "mass" if it's moving faster. Nothing in the electron changed, the change was what we thought we were actually measuring, not some intrinsic property of the object, but its total energy.
In QM, these definitions are further blurred. Particles, energy, fields, mass, all of it is "flexible" and not trivial to pin down. One can have a "mass-like concept" in QM which would be "the total internal energy of an object", but such a definition no longer serves a purpose. Another definition might be that matter is the class of particles called fermions, as opposed to bosons, but both cause gravity and have "mass like effects", because, under them, there's no real "mass".
This may sound confusing, but this true of most modern physics. Even simple things you think you understand, like "spinning", look very different today.
Comment: "Even simple things you think you understand, like "spinning", look very different today."  I presume you mean the 'spin' measurement of a particle.  I'm not sure it makes sense to say 'spinning' is something different that we typically think given that the term 'spin' was based on an incorrect model of what was really happening.  It's kind of like asserting that the general understanding of 'charm' or 'strange' is wrong because it doesn't consider how the properties of the types of quarks that bear those names.
Comment: I don't want to give you too hard a time here because it's good answer overall, it's just that picking the wrong word for a phenomena doesn't mean the word means something else.  A good example is 'lead': there's the metal and there's the kind in your pencil (graphite).  That doesn't mean we are confused about what lead really is.  It's just a misnomer applied to pencils.  What mass is or isn't is a far more substantial question.  It's not just semantics.
Comment: "given that the term 'spin' was based on an incorrect model of what was really happening" - exactly.
Comment: The point is that macroscopic spinning is still understood as exactly what people think it is: parts of an object not on the axis of rotation moving around that axis of rotation. The fact that that doesn't make sense in quantum physics, or at least is not really what spin is, doesn't mean that normal spinning looks any different in modern physics than in classical physics (although technically relativity might make it a bit different).
Answer: This response has been reorganized and had (a lot of) material added to it in response to a good point made in a comment. I have also appended some more in-depth information on mass and some other topics that I have a better understanding of now than I did when I first wrote this answer, and have added a third possible definition for matter. This is probably a lot more text than is necessary, but I figure "Why delete it?".
One good definition for mass is that it is a property of matter which determines it's motion according to certain equations. In classical mechanics, these are:

Newton's Second Law: $F=ma$
Newton's Law of Universal Gravitation $F_g=G\frac{m_1m_2}{r^2}$

(You can find explanations for these easily.)
Sometimes m in the first equation is called "inertial mass", and m in the second equation is called "gravitational mass", but the two are always proportional (i.e. equal with the right choice of the constant G)
Einstein's Theories of Special and General Relativity caused some reinterpretation of the concept of mass and introduced some new (more accurate) equations relating mass to motion. Νotably, it is necessary for inertial and gravitational mass to be equal for the General Theory of Relativity to be true.
For some definitions of mass, it might interest you to start looking at the Wikipedia page if you haven't already: https://en.wikipedia.org/wiki/Mass#Definitions
Given these mathematical definitions of mass, it becomes more reasonable to define matter as anything that has mass. However, since any collection of energy acts like it has mass to some extent in Relativity, it makes a bit more sense to define "matter" as "anything that has rest mass". "Rest mass" is mass as measured by an observer who is not moving relative to the object  being measured. Many physicists think that "rest mass" should be considered the only kind of "mass", but it's also popular in explanations of Special Relativity to say that things gain mass when they move at higher speeds, because of the way the equations work. Particles like photons, that have no rest mass and thus always travel at the speed of light, are usually considered "massless", but they do have momentum (which they can transfer to and gain from other objects in collisions), react to gravity, and would suddenly act like they had mass if you stuck them inside a ball with mirrors on the inside so that they bounced around forever (though it is practically impossible to get any significant amount of mass this way, particularly since mirrors don't reflect totally efficiently; other difficult-to-verify facts are that black holes gain mass when you shine lights into them and that hotter things have more mass).
The idea that mass is "how much matter is in something" is an intuitive explanation to give people an idea of what sort of things have more mass than other things, or even have mass at all, based on the idea that people already have an intuitive understanding of what matter is. This was probably more important in the past because the vague idea of "matter" or "substance" has a long history in philosophy that goes back far before Newton's formulation of physics gave a definite mathematical notion of "mass". I don't know this kind of history, but I would guess that the explanation that mass is "how much matter is in something" would have been more popular among early physicists due to the fact that "mass" was a new concept and "matter" was an old one. It should also be noted that "weight" is also a much older concept than mass.

Another way matter is sometimes defined is that it has mass and takes up space. Particle physicists tend not to concern themselves too much with the macroscopic idea of "matter", at least not in the sense of needing to define it, but this idea of "taking up space" is related to one particle physics definition: "Fermions" follow the Pauli Exclusion Principle, which says that no two identical fermions can have all the same quantum numbers while they occupy the same quantum system (which corresponds roughly to our notion of "place"). This is why only two electrons can occupy the same orbital in an atom or molecule. "Bosons", on the other hand, can have any number of particles in the same place. The main example of a boson is the photon. Sometimes, matter is defined as fermions, or at least things made from fermions. This can, however, be rather problematic.
On larger scales most of what we think of as matter is made of atoms. Atoms tend to repel other atoms if they get too close. This property of ordinary matter leads to the "normal force" in classical physics, and is why particles in gases bounce off each other. Apparently, this is electrostatic repulsion that is only possible because of the Pauli Exclusion Principle. Apparently, if electrons did not obey this principle, any collection of adjacent atoms would merge into something with neutron-star-like density.* I'm not really sure how this works, but you might check out the following sources:
https://en.wikipedia.org/wiki/Electron_degeneracy_pressure
https://aip.scitation.org/doi/abs/10.1063/1.1705389
https://www.quora.com/Is-it-the-Pauli-exclusion-principle-or-electrostatic-forces-that-explain-why-I-do-not-fall-through-the-floor
http://www.pas.rochester.edu/~rajeev/phy246/lieb.pdf
One problem with this definition is that many combinations of fermions are not fermions. In fact, somewhere between 10% and 100% (by mass) of what is usually considered visible matter (as opposed to dark matter**) comes in the form of bosons (things that do not obey the Pauli Exclusion Principle) that are made of fermions. Protons, neutrons, and electrons are all fermions, but any collection of an even number of fermions acts like a boson whenever it acts like a single particle as a whole. (I'm not really sure how groups of particles act like single particles, but they do.)
For example, a neutral Helium-4 atom has two protons, two neutrons, and two electrons — an even number of fermions. This is why Helium-4 becomes a superfluid when it is cooled down to near absolute zero. Helium-3 has one less neutron than Helium-4, and is thus a fermion, when viewed as a single particle. Thus, Helium-3 does not become a superfluid until it reaches much colder temperatures than are necessary for Helium-4. At those temperatures, pairs of Helium-3 atoms come together in what's known as "Cooper pairs". Each of these Cooper pairs is made of an even number of fermions, and so acts like a boson.
Many other familiar atoms and molecules — such as most hydrogen, carbon, nitrogen, oxygen, water, glucose, methane, ammonia, carbon dioxide, neon, and argon — contain even numbers of fermions. (I'm ignoring a lot of solids because they're more complicated to deal to deal with. Many of them are also made of bosons.)
Given all this, it might seem odd that anyone would even consider this definition. The reason they sometimes do is that, when considering only elementary particles (particles that aren't known to be made of anything else), almost anything we might come up with to be "matter" is made of fermions,*** and it provides a convenient way of saying that light and various fields, such as electromagnetic fields, are not made of matter. (See the second "extra info" section below)
One potential way to save this definition is to only consider what elementary particles (see 2nd "extra info" section) something is made of rather than any particles that are actually combinations of particles. Another interesting fact is that, while even numbers of fermions can combine to make bosons, no number of bosons can combine to make a fermion unless there is at least one fermion involved as well. Thus, you could also define "matter" as "anything that is made of fermions on some level".
However, it's questionable whether any of this is a particularly good idea. I suspect that a large part of the reason this gained any credence is because it extends a notion that existed before Quantum Field Theory was developed. This notion was the idea that light, and probably mesons,**** were simply excitations in fields (that maybe sometimes looked like particles) and could be created and destroyed at will by just transferring energy; whereas protons, neutrons, and electrons were "really" particles of (possibly indestructable) matter. I think this notion comes from before quantum physics got started, when Maxwell explained how light could be waves in electromagnetic fields and people knew about atoms and were just starting to figure out the various parts they were made of. It was pretty thoroughly extinguished when Quantum Field Theory became established in the mid twentieth century and showed that all known particles can be described as excitations in fields that have values at every point in spacetime (at least in terms of the "wave functions" that probabilistically predict the outcomes of measurements). Any idea of particle-indestructibility was pretty far gone even before that when matter-antimatter annihilation and pair-production were discovered.
Given this understanding of particle physics, it might seem reasonable to say either that matter is a purely macroscopic phenomenon or that all types of particles, including photons, could count as matter. At least, this would make about as much sense as saying that matter was fermions, and still might exclude things like spacetime, energy (since that's something particles and parts of fields have, not a substance), and sound-waves (although I think there are quantum-particle-like descriptions of sound: look up "phonon" and maybe "quantum acoustics", but those are generally called "quasiparticles" rather than "real" particles).
*Neutron stars are, of course, also generally considered matter. They are not made of atoms (at least not mostly), but they are still "baryonic matter" in that they are made of protons and neutrons (and maybe also electrons). It's just that A: it's mostly neutrons because most of the electrons merged with the protons to form neutrons, and B: they're all grouped together like one enormous nucleus. The "quark matter" that may be in some of them does not have the quarks divided into baryons, but would still generally be considered "matter".
**Obviously, "dark matter" has the word "matter" in it. Since the only thing we "know" about dark matter is that it creates gravity (and therefore is usually supposed to have other properties that go with mass), this terminology does tend to go with the idea that matter = mass. There is an idea (which has been loosing favor) that "dark matter" is actually just something we don't understand about gravity, or maybe a fifth force, in which case people would probably find the label inappropriate, but if it were any kind of particle, and even if it was all black holes, people would probably consider the name pretty justified (although I can imagine an argument that black holes have mass but aren't made of "matter", since they're likely just stable configurations of spacetime from an outside perspective).
***Well, there is the issue of binding energy. For example, protons and neutrons are usually said to be "made of" quarks, which are fermions, but most of the mass comes from the binding energy holding the quarks together, which really isn't fermions, so you have to ask what "made of" means.
****Mesons are bosons "made of" two quarks each (one matter, one antimatter, whereas protons and neutrons are "baryons" made of three matter quarks each). Some mesons are involved in the force that holds protons and neutrons together in the nucleus, i.e., they "mediate" the "nuclear force" in the same way that photons "mediate" the electromagnetic force. They also all have mass.

The idea that "matter" means "fermions" is not particularly useful, for the reasons given above (and maybe others). In fact, having a distinction between matter and non-matter particles is kind of unnecessary in quantum theory. One situation where particle physicists do still talk about "matter", however, is in contrast to "antimatter". Matter and antimatter have the interesting property that when a particle of matter and a particle of antimatter meet, they can "annihilate" with each other to release energy. This energy must come in the form of another particle, usually a photon. This photon can be considered to neither matter nor antimatter. Alternatively, it might be considered to be either matter or antimatter or even both at once. This is similar to how zero is often considered neither positive nor negative, but you can also say that +0 and -0 are both valid representations of the same number.
Elementary particles are particles that are not known to be made of any smaller parts. All elementary fermions have antimatter equivalents. One type of elementary boson also comes in two forms (W+ and W-), which I believe behave like matter and antimatter, but there is no good way to decide which is matter and which is antimatter. The other 4 known boson-types are Z-bosons, photons, gluons, and Higgs bosons. Gluons come in 8 colors, but there's no good way to decide what is matter and what is antimatter, and the others all have the property of being neither matter nor antimatter, as far as I know.
If you look at the table of elementary particles in the 2nd "extra info section", you'll see that there is a strong correlation between particles having a matter-antimatter distinction and them having mass and being fermions. There are exceptions, though. The Z and Higgs bosons have mass but don't have this distinction (I don't think), and W boson is a non-fermion that I'm pretty sure has a matter-antimatter distinction, although I don't think people generally define which version is which, since it's not a stable particle either way and both appear regularly.

Extra Info About Mass
As an aside, the current theory of where mass comes from is two fold:

Everywhere in space is filled with something called the "Higgs Field". Elementary particles that have "intrinsic mass" sort of bump into this field constantly in a way that makes them seem to be going slower than the speed of light, which all particles naturally go at according to this theory, and this is what makes them need to be pushed to move around at different speeds relative to other things. It is also possible that some particles get their "intrinsic mass" from some other unknown source.

Most of the mass in atoms comes from a seemingly different process (which is technically the same process). According to Special Relativity, objects moving fast relative to you seem to have more mass because they seem to take more energy to push. Also, according to general relativity, how much spacetime curves (i.e., how much and what kind of gravity there is) depends on how much energy is in a part of spacetime (which is weird, since kinetic energy is different depending on the observer's velocity relative to the object, but maybe gravitational potential energy makes it less weird?). These effects do apply to the "intrinsic mass" of elementary particles like electrons and quarks (since that is energy), but most of the mass of atoms actually comes from what's called the "binding energy" of protons and neutrons, as well as of atomic nuclei as wholes.This is usually classified as "potential energy", but it can also be thought of (probably rather inaccurately) as the kinetic energy of the quarks inside protons and neutrons zipping around each other at almost the speed of light, shooting "virtual gluons" between each other that pull them together via the nuclear strong force and keep them from flying apart. Protons and neutrons as wholes also can be thought of as zipping around each other quite fast inside the nuclei of atoms more complex than simple hydrogen. They are held together by the "residual strong force" which can be thought of as being mediated by "virtual mesons" that protons and neutrons shoot at each other, similar to how quarks can be thought of as shooting "virtual gluons" at each other and electromagnetic forces can be thought of as mediated by "virtual photons".All this talk of particles zipping around each other, and especially of shooting "virtual particles" at each other to "mediate" forces binding them together, is rather imprecise and misleading. These are all just intuitive explanations people give of quantum mechanical phenomena. Just as electrons come in wave-like "orbitals" organized into "shells" around nuclei, protons and neutrons exist in similar wave-like states organized into "nuclear shells", which each have different binding energies. Protons and neutrons don't have shells, because each of the quarks they are made of are different and so the Pauli Exclusion Principle isn't an issue, but they still exist in a wave-like state that has a certain energy. The energies of electron orbitals, and even of macroscopic movements, all have energy, which therefore affects the effective "mass" of objects, but these energies are usually completely negligible relative to the binding energies of protons and neutrons, or even the smaller binding energies of atomic nuclei as wholes, which are the energy source for nuclear reactions.

(The larger binding energies of protons and neutrons as compared to the atomic nuclei they group into are the main reason why matter-antimatter annihilation releases so much more energy than nuclear reactions. This is called "total conversion" of "matter" "into energy". Some of that energy comes from the "intrinsic mass" of elementary particles being converted into photon energy, but, if any protons or neutrons are annihilated, most of the energy comes from the binding energy of those particles being released.)

Extra Info About Fermions, Bosons, and Quantum Theory
These are the elementary particles according to the standard model:

These are called "elementary particles", because they aren't known to be made of any smaller parts. You should recognize the electron; photons are what light is made of; and protons and neutrons are basically combinations of up and down quarks.
As you can see, all these particles have a quantum number called "spin" (also known as "quantum angular momentum"). Unlike macroscopic spinning objects, particles can only have spins which are multiples of 1/2 (in standard units) and they can only spin in two directions — positive and negative (often called "up" and "down", but I'll avoid that lest it cause confusion with the quarks). The sign of the spin (+ or -) is basically a matter of orientation, rather than anything fundamental to the particle.*
Any particle whose spin is an integer is a boson. Any integer whose spin is some odd number divided by two (e.g., 1/2, 3/2, 5/2, ...) is a fermion. You can put as many bosons as you want into the same quantum state/location (they just add up), but you can't do this with fermions. All the elementary fermions in the Standard Model have a spin of 1/2. Any combination of an odd number of these is a fermion, even if some are negative and some are positive. Likewise, any combination of an even number of these is a boson, even if some are positive and some are negative. (This is easy to prove: Each fermion is either adding 1/2 or subtracting it. The difference between the two states is 1, so no amount of flipping spins will change the sum to or away from being an integer.)
Examples:
Proton = 2 up quarks and 1 down quark. Two of these have positive spin and one has negative spin (or vice-versa). 1/2 + 1/2 - 1/2 = 1/2: Protons are fermions.
Neutron = 1 up quark and 2 down quarks. Spins are same as proton: 1/2 + 1/2 - 1/2 = 1/2: Neutrons are fermions.
Δ+ Baryon = 2 up quarks and 1 down quark, just like the proton. Unlike protons, all have spins in the same direction:. 1/2 + 1/2 + 1/2 = 3/2: Δ+ baryons are fermions.
π0 Meson (Neutral Pion) = either 1 up quark and 1 antimatter up quark or 1 down and one antimatter down quark. Spins facing opposite directions. 1/2 - 1/2 = 0: π0 Mesons are bosons.
ρ+ Meson = 1 up quark and 1 antimatter down quark. Both spins facing same direction. 1/2 + 1/2 = 1:  ρ+ Mesons are bosons.
Alpha particle (4He nucleus) =  2 protons and 2 neutrons. Each has total spin 1/2. Two have + spin and two have - spin (at least in ground state). 1/2 + 1/2 - 1/2 - 1/2 = 0: Alpha particles are bosons.
Neutral Ground State Helium-4 Atom = One spin=0 nucleus and two electrons. Both electrons occupy the s1 shell and thus have opposite spins (according to the Pauli Exclusion Principle). 0 + 1/2 - 1/2 = 0: This type of atom is a boson.
Protium H2 Molecule = 2 protons and 2 electrons, each spin=1/2. Both electrons are in the σ1s orbital (the chemical bond) and thus have opposite spins. The spins of the two protons may either be pointing in the same direction (orthohydrogen) or in opposite directions (parahydrogen). In orthohydrogen: 1/2 + 1/2 + 1/2 - 1/2 = 1. In parahydrogen: 1/2 - 1/2 + 1/2 - 1/2 = 0. Either way, the spin is an integer, and so the particle is a boson.
In quantum field theories, these particles are actually the result of vibrations in various "fields", which have values everywhere and everywhen in spacetime. (This makes more sense if you know about Fourier series and particle wave-functions.) An electron is a manifestation of vibrations in the electron field, and the photon is a manifestation of vibrations in the electromagnetic field (which I suppose could also be called the "photon field"). One consequence of this wave-particle duality is that electromagnetic fields can more-or-less be modeled as the sum of an infinite number of "virtual photons" being exchanged between charged particles. The really accurate explanation is more complicated than that,** but this is the reason that people sometimes say that the electromagnetic force is "mediated" by photons. Similarly, the nuclear strong force is mediated by gluons and the nuclear weak force is mediated by W and Z bosons. If gravity can be explained by a quantum field theory, then it is mediated by spin-2 bosons called "gravitons". The so-called "nuclear force" or "residual strong force" that holds protons and neutrons to each other to form nuclei larger than Hydrogen-1 is "mediated" by π, ρ, and Ω mesons (mesons being bosons made of quark-antiquark pairs). (The animation linked below demonstrates the basic idea of how these particles can be transferred between the nucleons. This possibility is necessary for the quantum field theory to explain how energy is transferred between the nucleons to bind them together.)
https://en.wikipedia.org/wiki/Strong_interaction#/media/File:Nuclear_Force_anim_smaller.gif
*Actually, there is something related to spin-direction called "chirality", which is fundamental to particles, but it changes constantly (and is thus always undetermined) for charged leptons and quarks as part of their interactions with the Higgs field, which give them their "intrinsic" mass. This "chirality" (which is either "left-handed" or "right-handed") determines whether or not a particle can interact with the weak nuclear force. I'm not sure whether massless particles come in different chiralities. (I just know that their "helicity", i.e. spin-direction relative to motion, is purely dependent on their chirality). I know that only left-handed neutrinos and right-handed antineutrinos have been observed (since other kinds would only interact with gravity, i.e. be "dark matter", if they existed, which would explain why they've never been created by any process we know of) it's unclear whether or not the "intrinsic" mass of neutrinos comes from the Higgs mechanism (which I suppose would flip their chiralities back and forth). I'm very unsure about the chirality of the W and Z bosons, which I believe do derive their mass from the Higgs field but also only interact with particles of certain spins.
**Sometimes the photons turn turn into electron-positron pairs. Also, it's not so much an infinite number of particles as an infinite number of paths particles could take, which all add together to make a "probability amplitude", which is part of how things are defined in quantum physics, since the outcomes of measurements are not certain. Look up Feynman Path Integral.
Comment: I don't know if it's wise to propagate the "matter = fermions" definition, since even at the subatomic scale it's violated by lots of things that we normally call matter. In particular, according to your definition, _all mesons are not matter_, because they are all bosons with integral spin.
Comment: Yeah, that's a good point. Mesons don't come up much outside of particle physics, but I just realized that many atomic nuclei and probably atoms are bosons, too. For example, I believe that Helium4 nuclei are bosons, and since they normally have two electrons, I bet the whole atom might act like one too. They definitely are normally considered matter, though. To be fair, though, all of these things contain quarks and leptons, which are fermions, which is why it's easy to forget these things.
Comment: I changed the answer to address the problem. Hopefully it wasn't too drastic; I didn't really remove anything from the answer.
Answer: Photons (electromagnetic fields) are usually massless, but I believe photons in a superconducting state have mass (symmetry spontaneous breaking). Mass does not mean whether a particle is "matter" or not. I believe that all particles in particle physics are "matters".


What are the top useful Phpstorm plugins for Magento 2 development?

Question:
What are the list of useful magento2 development tools?
What are the top phpstorm useful plugins for magento2 development?
Comment: 1. Always have a browser tab open with magento.stackexchange.com on it.
Comment: 1. Always have a browser tab open with magento.stackexchange.com on it.
Answer: 1) PHPStorm with XDebug:
PHPStorm is my favorite IDE. It is an advanced IDE for PHP developers.
Many developers still use only var_dump and die to debug the system. From my experience, these techniques are not powerful. They possibility will break the application.
Magento 2 is a huge system. We should try with XDebug. With XDebug, we can see how the system works, why the exception occurs.

2) PHPStorm plugins for Magento 2 development:
There are some useful PHPStorm plugins. I used two free Plugins: Magento2 and MaGinto.

There is a good paid Plugin: Magicento. You also can try.
Comment: thanks, How can i go or navigate deeper into core functionalities of magento from phpstorm
Comment: We can use the blue buttons: http://imgur.com/a/3GJd4
Answer: Magicento help for development (printscreen).
Answer: for code standard, use PHPMD & PHPCS
https://www.atwix.com/magento-2/configure-code-sniffer-for-phpstorm/
Answer: I love PHP Inspections, probably the best plugin out there for PHPStorm.
Here are my top 5 plugins for PHPStorm:

PHP Inspections (EA Extended)

Framework Support Plugin (Symfony)

Key Promoter X

PHPUnit Enhancement

JetBrains Toolbox App

I've made a video showing the possibilities of each plugin: https://youtu.be/h18-RtRqHZY


who has the power to interpret the UN charter?

Question: does the power to interpret the UN charter explicitly fall within the hands of the state parties ? and what would be the consequences of multiple state parties having different interpretations ?
Answer: Everyone has the power to interpret the charter, as with any document.  The important question is who has the power to resolve disputes of interpretation?  Even there, as with most of international law, the answer is more or less "anyone whose authority all parties to the dispute accept."
The charter itself establishes (chapter 14) the International Court of Justice as the UN's "principal judicial organ" (article 92).  Members of the United Nations agree to comply with the court's decisions subject to enforcement by the UN Security Council on application of the opposing party (article 94).  Article 95, however, says that members may also seek dispute resolution in other tribunals.  It does not apply any limits to this freedom, much less exclude disputes of interpretation of the charter itself.
Answer: The UN Charter would be interpreted by any entity for which it has relevance, whether judicial, legislative, or executive.
For example, in Canadian law, the United Nations Charter has been relevant for revealing Canada's committment to international human rights norms and the corresponding presumption of conformity that results in domestic law. As that is a matter of domestic law, it is of little significance that states might differ in their precise interpretation of the UN Charter, although given its level of generality and the use to which it would be put in domestic law, the differences would not be significant.
Domestic courts might also look to others' interpretations as a comparative exercise when interpreting; this is another factor that would keep interpretations similar.
Executive and legislative actors would interpret the UN Charter to understand the state's obligations to the world. And they would certainly look to judicial decisions for guidance.
At international law, any UN body can interpret the UN Charter: judicial bodies, committees, special rapporteurs, etc. They of course would look to each others' interpretations, especially that of the ICJ, with the goal of coherence.


Why can't we produce visible light from a radio transmitter?

Question: Producing visible light from a radio wave transmitter: why is it not possible? If it is, what are the limitations?
Comment: Why can't we? http://www.physics.umd.edu/deptinfo/facilities/lecdem/services/QOTW/arch13/q252.htm and on this page http://www.flateh.narod.ru/145mhz.htm demonstrated with a 145MHz transceiver and a fluorescent light.
Comment: Actually [Radio antenna producing waves in the visible spectrum](http://physics.stackexchange.com/q/74892/) would be a better duplicate, but the SE won't let me go back and change a duplicate link.
Comment: I loved that demo in my intro physics class. Will always remember it.
Comment: The link I've suggested is actually about the reverse process i.e. light inducing an oscillating current, but the physics is the same. It's because the frequency of visible light is at or above the plasma frequency of the metal aerial.
Comment: @JohnRennie: That's a very good answer on that previous question. It seems that the plasma frequency of metals can be adjusted by patterning into meta-materials (seems plausible enough), so the experimental realization of antenna structures for visible light may not be out of our reach for long.
Answer: Radio antennas generate electromagnetic fields. Light is a physical particle of energy called a photon. Since the the radio antenna doesn't generate particles of energy, no matter the frequency, it can't produce light. The flow of current in a conductor generates an electromagnetic field that propagates from the conductor. The generating of photons from an electric current is a different process and is on the atomic level. The electric current releases energy (photons) from individual atoms. Probably the most commonly know application of this process is the light emitting diode (LED). Until the scientific community admits that light, in fact, isn't part of the electromagnetic frequency spectrum, since light has no electric or magnetic properties, these confusions will continue.
Comment: This is simply wrong. All electromagnetic radiation, whether radio waves or visible light can be treated either as a wave or a particle i.e. photon. The difference is only in the energy of the photon. You're also wrong that current can't generate light directly as this is exactly how synchotron radiation is generated. It just can't be done in a metal wire.
Comment: Last things first. Current in a wire can generate photons, that's how an incandescent light bulb works. I just isn't electromagnetic. The synchrotron does generate photons. It appears when the super accelerated charged particles gain enough energy they produce a photon which having no magnetic property are no longer held by the super magnet and fly off to be seen as light. This supports that light is not electromagnetic. Thank you for pointing out a rare process for generating photons.
Comment: Would producing light in the visibl spectrum degrade the quality of antennas ? Wearing out ?


android unable to use hdmi in creative tab and need to be notified in all(maximum) devices as soon as hdmi is plugged

Question: may be possible duplicate of hdmi support in android.
I am working on XYZ video encrypted app.But need to manage hdmi also to overcome the encrypted video pitfall.
As per my search I found that these are not in official docs and are provided by specific vendors Api as that of Motorola.
I have explored much and found that these are vendor specific , there is no unique api or documentation to serve the needs of all the devices.
My device is:
Creative ziio 7 OS :2.2.1 build number:v2.00.13-FROYO.
But please suggest and answer the following via the google white papers or your personal experience:

If a certain android device has hdmi hardware support, then how can we detect it programmatically.
If the hardware is supported in device. Then if the connection is    made to hdmi my app need to be notified about that.
(like using a recevier etc).
I am also unable to connect the hdmi in Creative ziio 7 with hdmi
cable (AWM 1.3 cable)  to my hp notebook pro laptop

I have noticed about that certain vendors provide hdmi api like MOTOROLA http://developer.motorola.com/docs/motorola-hdmi-status-api/
Also we can detect the USB Plug Status in all devices by using
<code> <action android:name="android.intent.action.ums_connected" />
</code>
So is there any way for hdmi also. But need to have a general concept to do the same for all devices.
Answer: Although there does not appear to be an official standardized way of doing without using vendor specific APIs, on later versions of Android 3.0+, it seems like the Android source code references a broadcast action intent that most vendors seem to be implementing. This intent is "android.intent.action.HDMI_PLUGGED". If you're targeting these later OS versions, this seems to be pretty reliable from my experience in detecting when HDMI is connected.
Answer: As far as I know, there is no HDMI support inherently in the platform. Each hardware vendor hacks up their own implementation via the hardware composer hardware abstraction layer. Meaning, there isn't a way for you to programmatically interact with anything HDMI related with the standard Android SDK.


Deploy Umbraco 500.19 error This configuration section cannot be used at this path

Question: 0 down vote favorite
I have been running all over the web trying to find a solution to this problem. I am trying to deploy an umbraco site to a vps build is:
Windows Server 2008 R2 IIS 7.5 Umbraco CMS
app pool integrated v4.0
I have tried many different solutions. II tried to do what was listed here: IIS - this configuration section cannot be used at this path (configuration locking?)
I found that I don't have 'in the features window, Click: "Internet Information Services"'. I'm not sure if that is related or not.
This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false".
that is the error I am getting, error code 0x80070021. Its happening on this line . I have also tried the solution listed here:
http://forums.iis.net/t/1155232.aspx
to no avail. There shouldn't be any issues with file permissions either... I added IIS_IUSRS and IUSR with full control to see if that had any part.
Any info is appreciated.
Answer: Stupid mistake... but have to admit the error wasn't very descriptive.
found the answer here: http://forums.asp.net/t/1735022.aspx
"Verify framework 2.0 is registered with IIS, If it is not registered, to do this
open the command promt=> C:\Windows\Microsoft.NET\Framework64\v2.0.50727 aspnet_regiis -i"
though I installed v4


Why do I need to create a new CSR?

Question: My website on a shared server has a SSL certificate installed and I want to move the certificate to a dedicated server that's supplied by a different hosting company. The current hosting company says that they need a new CSR. Why can't I just re-install the existing one on the new machine without creating a new CSR?
Comment: exactly , you can/should be able to move it as suggested, It looks like  they want to create new SSL cert if they are requesting CSR (Certificate signing request). Just transport SSL key and crt and that should be enough for them to set it up properly
Answer: It's probably because they have a system that does not allow to recover the original private key. If they use a kind of HSM (Hardware Security Module) then they entered the private key into the system once they generated it and then shred the key or even the HSM has a functionality to generate a request not exporting the private key.
Answer: If you're on a shared host, it's likely that the certificate that's in use is also used for a number of other sites. You should be able to check the list of Subject Alternative Names (SAN) in that old certificate.
In such a situation, the certificate isn't really yours, but you've authorised your hosting company to be issued with a certificate that covers your domain name. If they gave you the corresponding private key, they'd effectively give you the ability to host all the other shared host names on that server, which is certainly not acceptable for the other customers.
Even if that certificate isn't shared with other customers, the hosting company will have access to its private key, and it could technically keep serving your domain name. It's good practice to re-key your certificate when moving from one hosting company to another, at least to take control over your old certificate away from the old company.
When moving to a new host, you would want:

to make sure that the old certificate is revoked, so that the hosting company can no longer server your host name with that certificate;
get a new certificate for your new dedicated host.

To prevent the old certificate from being used any further, it makes sense to generate a new key-pair, in addition to revoking the old certificate (since whoever controls that old certificate would also have its private key). Hence, you need to create a new CSR.
Comment: One would still have to trust that the original hosting company revokes the certificate though?
Comment: Yes, although in principle, it would be legitimate for the domain owner to contact the CA directly to ask for the certificate to be revoked. It would make sense for them to act upon such a request, but whether they'd do it may be another matter.

Why do I need to create a new CSR?


Is it possible to have versions of a document (other than the current) automatically transfered to another document library?

Question: I have a slide library that has major and minor versions enabled. Once a slide is updated to it's current version, I want the "new" old version to transfer to another document library. Is this possible? If so, how would I do it?
Comment: using OOTB functionality you can able to see version history of document and restore it as per requirement.

If you need to move old document before updating you need to do custom screen for upload document maybe it is not feasible using OOTB functionality.
Answer: Something like this might be possible using a custom workflow, though it sounds fiddly.
Why not just switch off versioning and make users append a date to the file they upload instead?  Each file is then a stand-alone file.  Then you could create a workflow to copy the old file to the other document library.
You would just need to come up with a system so Sharepoint knows which file is the old file it needs to move.  You could have a tag for the document type e.g. Project Finance and another field with a unique number '1 to infinity' (you could use the ID field that the List comes with).  Get the workflow to check against the Project Finance tag, if there are two documents, the workflow checks the Created Date and moves the oldest one to a new location.


Draw dynamic graph on python

Question: I am trying to draw a dynamic graph which I want to control ( moving edges or nodes, update data of edges or nodes, click on edge to show more information...).
I have tried several programs and packages like prefuse, networkx and also processing.
But with these, we cannot control edges (onClick listener for exemple) we can just control nodes.
I have also a little problem because I am using python to parse the data and binding languages is a new thing for me , I have tried Jython with processing which was really slow...
I will appreciated any help of you
Thank you!
Answer: Take a look at this example
http://developer.qt.nokia.com/doc/qt-4.8/graphicsview-elasticnodes.html
You should be able to make the same using Python Binding for C++/Qt aka PyQt or Pyside. It should run and render much faster.

Draw dynamic graph on python


Is genenoristy with the expectation of Divine reward selfish and less admirable?

Question: If you help me because you want Allah to give you rewards or presents , then there's nothing special about your kindness , isn't it?. I would say that an Atheist helping other people is BETTER than a Moslem helping other people because they want Allah to give him 'presents' in returns (sorry to say this). There is no sincere thing on this planet. Would believers still help other people if Allah were never promise them anything, Allah never punishes them, and heaven and hell don't exist??
Comment: I edited the title to make a central question stand out. Questions like these are related to study of akhlaq in Islam which has been discussed by Muslim scholars of ethics. So if there are clearly written, they are on-topic.
Answer: The premises of your question are objectionable.
Religious people may give out for Divine reward, but they also give out because religion teaches them to practice compassion and charity. Religion tells them that they make up one family descending from Adam and Eve, and together they are like brothers and sisters; that they must be concerned for one another. Islam tells us that we are all created from "one self" and all have a share of Divine spirit in us. So this ideally gives Muslims a sense of community, connection and care. And like every community system, there are rewards for cooperation.
A deeper analysis tells us that man is never truly and fully selfless, simply because the self is always with us. Islam talks about different types of nafs and that the nafs will finally taste the consequences of his deeds. Therefore the choice is between following your lower nafs or higher nafs, your evil nafs or your angelic nafs. There's no other alternative.
The higher nafs, due to having a greater share of the Divine spirit that is shared by all of us, inspires deeds that have greater benefit than the immediate benefit to the individual doing the deed, because the Divine spirit is connected to all individuals. But once we follow our base desires that are more attached to our bodies, we move further from this spiritual unity and embrace greater individuality. So it is recognition of spiritual unity that engenders compassion and charity in us, and heavenly rewards are only manifestations of this greater consciousness which we call "faith" and good deeds are consequences of this faith.
An atheist may engage in good deeds but if he is truly doing it without expecting tangible reward (which is questionable), he must be doing it for recognition of some unity and connection among human individuals and developing a charitable feeling as a result. This charitable feeling can be said is itself the reward of the charitable deed. When one feels generous, it is due to compassion that one feels in his heart. With compassion indeed comes a feeling of pleasure, "a feel good" experience which acts as both the motivation and reward for acts of generosity. When you understand this, you understand that even an atheist's charity is not truly selfless. There's a good feeling and an urgency to relieve one's self from a pressure on one's conscience that motivates the good deed.
Now Islam tells us this sense of connection and compassion that motivates us to generosity is in fact a spiritual connection. An atheist may not agree, but again the atheist's admission or non-admission doesn't change the fact.
However, because a believer's good deed is based on this deep consciousness of our spiritual unity, he is far more likely than an atheist to spend in charity, because this consciousness itself invites greater share of the Divine spirit and mercy to the believer that is in turn passed around by the believer to others.
This I think is what ideally runs beneath a Muslim act's of charity. But I understand most Muslims tend to think of charity as a "divine decree" that we must just fulfill to attract Divine reward, which gives the wrong impression that an atheist doing good deeds is doing it without expecting reward. This is unfortunately the consequence of the legalistic reductionism of religion that is prevalent in most of the Muslim world, but if we recognize that reward is just the consequence of greater participation in the Divine mercy and spirit, and that this sense of mercy and spirit is immediately felt and present in our good deeds, to greater or lesser degree, giving us a sense of pleasure and satisfaction, then it is impossible to argue there can truly be no expectation of reward with acts of generosity.


Why wasn't Davros exiled by the Kaleds?

Question: In Genesis of the Daleks, the Doctor is forced to try to alter the evolution of the Daleks. Davros is the chief scientist on Skaro. By the first century of the war with the Thals, some Kaleds were mutated and quickly exiled. Davros was clearly mutated because he looks nothing like the Kaleds, so why was he never exiled? And how did he obtain that power?
Answer: Although the cause of Davros' appearance has never been explained in any televised episode, audio plays and comics have established the story that his appearance is the result of being injured in an explosion caused by a Thal warhead, not the result of a mutation (and the BBC has made a point of avoiding any official policy as to what qualifies as 'canon', it's up to individual fans to decide whether they want to incorporate spin-off material into their personal headcanon). This was detailed in the I, Davros audio series from 2006 which delved into his past--the Doctor Who Reference Guide has summaries of the plots of pretty much every Doctor Who story including I, Davros which you can find at the bottom of the main page--it's a four-part series, the parts are "Innocence", "Purity", "Corruption", and "Guilt". The explosion occurs towards the end of the one titled "Corruption", and these stories also go into detail about his rise to power, which you had also asked about.
The Davros page on the TARDIS wikia also gives a shorter summary of his biography as established in spin-off media, and also shows a panel from a comic titled "Up Above the Gods", published in the July 1995 issue of Doctor Who Magazine, which seems to show an image of the aftermath of the explosion--the caption suggests that this is a depiction of the explosion that caused his disfigurement, though I haven't read it and can't find any detailed summaries. But assuming that's correct, this was probably the first source to establish that his appearance was the result of an explosion.
Answer: The scientists within Kaled society formed an "Elite group", that wielded incredible influence:

DOCTOR: Years ago the Kaled government decided to form an Elite group. The best scientific brains in every field.
HARRY: A sort of Think Tank.
DOCTOR: Yes. But over the years the Elite has become more and more powerful, and now they can demand whatever they like.

Davros was the head of this Scientific Elite. Regular soldiers and citizens affected by the mutations might be banished from the city, but apparently his position of power gives him immunity. Whether that's because he simply decrees it so, or because the rest of Kaled society believes him too valuable to lose, isn't clear – but it doesn't really matter.
Alternatively, it may be that nobody outside the Kaled scientific community know of Davros's mutations. As Ronson explains:

RONSON: Well, I must. There are a few in the Kaled government who still have the power to act. If they knew the truth, they would end Davros' power, close down this bunker, finish the Elite.
DOCTOR: Then go to them, Ronson, go to them.
RONSON: But I'm not allowed in the city. Security here is absolute.

If Davros entered the Dome with a healthy body, and has suppressed any messages about his health, then nobody would know to exile him because nobody knows that he's mutated. (And if you were one of his subordinates inside the Scientific Dome, would you suggest it?)

Why wasn't Davros exiled by the Kaleds?


Body Rotation in a Molecular Dynamics Simulation

Question: I have been trying to simulate particles trapped in a parabolic potential in two dimensions. Due to the circular symmetry of the system, in the ground state at zero temperature, the particles are seen to arrange themselves in concentric rings. As I increase the temperature gradually, the expected result is to observe fluctuations about the mean position. However, due to the circular symmetry in the system, the particles are seen to undergo a body rotation. Can anyone please suggest a way to circumvent this self-rotation? It is imperative that the total energy remains constant during the simulation.
Comment: It sounds as if angular momentum conservation about the symmetry axis of the paraboloid potential is being violated (rather than energy conservation). And if you have a constant temperature thermostat switched on, you should not expect energy conservation anyway. I doubt that anyone will be able to guess the reason, without knowing more details. Are you using a package, to perform the MD, or your own program? How is the thermostat implemented (it may simply be a source of external overall torque).
Comment: I have written my own program in FORTRAN. The thermostat implemented is the simple velocity re-scaling thermostat.
Answer: It's hard to guess, as I said in my comment, but I'm offering this answer anyway. Most molecular dynamics thermostats do not respect angular momentum conservation. This is because most MD simulations use cubic periodic boundary conditions, in which angular momentum is not conserved (the boundary conditions break spherical symmetry). Therefore, I reckon that your thermostat imparts some angular momentum about the symmetry axis, which causes the system to rotate. Either that or your method for giving the particles an initial set of velocities results in nonzero angular momentum.
If that is the cause of the problem, it may be possible to apply a thermostat which avoids it. There are thermostats which are Galilean invariant, and preserve linear momentum. Some of them also preserve angular momentum. For example the Lowe-Andersen thermostat thermalizes randomly selected pairs of atoms $ij$: $\mathbf{v}_i \rightarrow \mathbf{v}_i+\Delta\mathbf{v}$ and $\mathbf{v}_j \rightarrow \mathbf{v}_j-\Delta\mathbf{v}$, choosing $\Delta\mathbf{v}$ to be parallel to the vector $\mathbf{r}_i-\mathbf{r}_j$. The magnitude $|\Delta\mathbf{v}|$ is chosen from the appropriate probability distribution. Then the change in angular momentum is $m(\mathbf{r}_i-\mathbf{r}_j)\times\Delta\mathbf{v}=0$. For simplicity I'm assuming equal-mass atoms.
Otherwise, my advice would simply be to choose initial velocities randomly, apply a global correction to cancel out the total angular momentum, and allow the system to equilibrate without adjusting the velocities, or at worst, simply scale them all up and down by a common factor to achieve the desired temperature.
[Edit following comment]
To remove the initial angular momentum: here is one scheme, but it is easy to devise other versions of it. I assume all masses are equal, $m$, and that the motion is in the $xy$-plane. For each particle $\mathbf{r}_i=(x_i,y_i)$ calculate the distance from the origin $r_i=|\mathbf{r}_i|=\sqrt{x_i^2+y_i^2}$, and construct the unit tangential vector $\mathbf{t}_i=(-y_i,x_i)/r_i$ (see diagram).

The idea is to adjust the velocity of every particle by $\Delta v \mathbf{t}_i$, in the tangential direction. The magnitude of the adjustment, $\Delta v$, is to be determined. By construction, the change in angular momentum about the origin will be $m\Delta v r_i$ for each particle, $m\Delta v \sum_i r_i$ in total, and we just need to choose $\Delta v$ to make this cancel the initial angular momentum.
The angular momentum ($z$-component) is given by the vector cross product formula, which we can easily rewrite in terms of the tangential vectors:
$$
L_z = \left(m \sum_i \mathbf{r}_i \times \mathbf{v}_i\right)_z
= m\sum_i ( x_i v_{i,y} - y_i v_{i,x} )
= m\sum_i r_i ( v_{i,x} t_{i,x} + v_{i,y}t_{i,y})
= m\sum_i r_i ( \mathbf{v}_i\cdot\mathbf{t}_i )
$$
From this we can calculate the necessary $\Delta v$ to cancel it out
$$
m\Delta v \sum_i r_i = -m\sum_i r_i ( \mathbf{v}_i\cdot\mathbf{t}_i )
\qquad\Rightarrow\qquad
\Delta v = -\frac{\sum_i r_i ( \mathbf{v}_i\cdot\mathbf{t}_i )}{\sum_i r_i}
$$
and then you simply replace each particle velocity by
$$
\mathbf{v}_i' = \mathbf{v}_i + \Delta v \mathbf{t}_i
$$
Do this once, at the start, after you have chosen random initial velocities. Double check that it worked, by printing out the new total angular momentum: it should be zero. Thereafter, provided your thermostat simply entails multiplying all velocities by the same common factor, the angular momentum should be conserved at zero. The only numerical problem that I can see will arise if you have placed a particle exactly at the origin (because then $\mathbf{t}_i$ is undefined). You should avoid doing that (or exclude such a particle from the calculation).
Comment: Thank you for your answer. I have initialised the positions and velocity randomly and have used a velocity re-scaling thermostat the equilibrate the system. Could you please elaborate on  the "global correction" that I could use to eliminate the angular momentum? Shouldn't the total angular momentum be conserved as the system is rotationally  invariant?
Comment: @Mami I have edited my answer accordingly, hope this helps.


Change merge shortcut?

Question: I have a High poly mesh and I have decided to make the low poly by merging as it is easiest for me. Would it be possible to change the W Hotkey , so that it merges to the center automatically? It is time consuming pressing W > Merge > Center.
Comment: no , This is because im making the low poly have edges which i need  and it dosnt work very well
Comment: Would the decimate modifier work?
Answer: Blender 2.8x
As of Blender 2.8x the 'Merge at Center' shortcut has been removed so you would have to create a new one. Right-click  RMB the menu item, click 'Assign Shortcut' and choose whatever you like:

Alternatively you can add it to the new 'Quick Favorites' list. That way you can access the operator by using (Q) in the viewport.  RMB the menu item and select 'Add to Quick Favorites':

Another option is to create the shortcut manually. Go to the User Preferences > Keymap, then unfold 3D View > Mesh > Mesh (Global) and add a custom shortcut item by clicking 'Add New'. Set the identifier to mesh.merge, it's type to 'At Center' and the actual key event to W:

Blender 2.7x
As always in Blender Right-click  RMB the button (menu item in this case) and select Change Shortcut will do the trick. If you want to reset it, original shortcut (default value) is Alt+M for all merge methods (menu items). For this reason you could also disable/remove unnecessary shortcuts in this dialog to prevent that the dialog appears:

Merge At Center (without Dialog)
Another option is to set the shortcut via User Preferences (Ctrl+Alt+U). Select the Input Tab and type: merge in the search area or simply unfold 3D View > Mesh > Merge:
Comment: Hi! Right, it's now called via mesh menu and can not be edited easily... However, you can either create a new shortcut using `mesh.merge` as described in my answer for 2.7x or just add it to the new quick favorites operator list (`Q`) @BenRacicot
Comment: Updated my answer for 2.8x @BenRacicot
Comment: Hey @p2or could you update this for 2.83? `mesh.merge` doesnt seem to exist in the keymap options and `merge`  does not have the `At Center` option.
Comment: Hey @p2or actually `mesh.merge` does not seem to exist anymore when searching. Were you able to successfully replicate your answer for 2.83?

Change merge shortcut?


bathroom aerator doesn't want to screw tightly into place

Question: We have 2 identical faucet. We change the aerator of 1 without trouble. The second one is not staying in place. We tried to put some silicone around the threaded faucet, but it is not working. We are thinking that when we unscrew the aerator, the internal threaded must have some deposit and today it is too loose. What can we do ?
Answer: Take a rag soaked in lemon juice, vinegar or CLR and shove it up into the faucet against the internal threads for a few hours. Keep re-soaking the rag. Then brush the threads with a toothbrush and reinstall the aerator. Remember to use the washer that came with the aerator. Oh, don't use the toothbrush on your teeth...
Answer: You may have cross-threaded the aerator when you put it on. That would allow it to screw on 1 turn, maybe 2, but then it would jam as though it was tight, but it wouldn't be tight.
Once cross threaded, it just won't go on right anymore. You'd have to "chase" the threads on the faucet to recut and clean them up, and do the same for the aerator. Replacing the problem aerator again would probably be easier than trying to chase the threads on it.
You could try swapping the aerators from one faucet to the other, but if you have cross threaded, you risk damaging both aerators.


participle and modal verbs

Question: I am not sure whether participle or gerund of modal verbs is possible in english. For example we have the sentence: Having introduced the speaker, the chairman opened the meeting. What would be the correct form when using the modal verb "must"? Is it "having had to introduce the speaker…"?
Comment: You can simply use *Having to*, e.g. *[Having to act quickly, he grabbed the bust from the window-sill and struck Jason with it, watching as he fell under the desk.](https://books.google.co.th/books?id=uxbQBwv0wH0C&pg=PA231)*
Answer: You have it exactly right. The full modals (can/could,may/might,must,shall/should,will/would) are 'defective': they have no non-finite forms (participles and infinitives) and do not inflect for person and number. That's one reason why the 'periphrastic modals' like HAVE to, BE going to, BE able to have increased in use over the last couple of centuries.
Comment: @Araucaria Most of what schoolteachers call 'tenses' in English - progr - essive, passive, perfect - .are *periphrastic*. It's the old-fashioned term for what is now usually expressed by the *synthetic/analytic* contrast. And the periphrastic modals are those which express the same sense as the ordinary modals by periphrasis.
Comment: @Araucaria: Presumably, the same as it would in any other context *(circumlocutory, using roundabout phrasing)*. Thus, in English, the *past* tense is conveyed using inflection, but the *future* can only be indicated by periphrasis or idiomatically established context (contextual *I am going to die someday*, as opposed to periphrastic *I **will** die*).
Comment: +1 :) But, what does 'periphrastic' mean (in this context)?
Comment: @FumbleFingers Thanks, suddenly realised I've been reading that for ages but didn't really know exactly what it meant ...

participle and modal verbs


Realized made a mistake when I took my last job. How do I approach other companies after rejecting their offers?

Question: Six months ago, I had three offers on the line, and I chose the one I thought was a better fit for me.  However, this company was horrible and had some ethical issues going on.  As an accountant, I will never participate in unethical situations, so I decided to leave this company.  My problem now is that those other companies were on my top list (and still are), but I don't know how to approach the HR managers and ask them to reconsider me as a candidate.
Answer: Asking the company to reconsider a previous offer rarely helps, and it only makes you appear foolish and immature. If you are interested in working at a company you have previously rejected, you make a fresh application (perhaps for the same role, or maybe even a new role).
Any reasonable HR or hiring manager knows that candidates rejecting offers is a part of the game. Getting a job offer rejected doesn't mean an insult, it only means that at that time, you decided not to accept the offer due to your reasons.
The situation has changed since then. Reasonable people would recognize that under the new set of circumstances, accepting the offer might work for you. If you are good enough for the role, there's no reason why they would hold a "grudge" for your previous reject and let go of a good candidate.
You must be aware, though, that some companies have a policy about the minimum duration a candidate has to wait before applying for a job again.
Comment: Absolutely agree. You'd better be smart when you reject an offer, too. I would not literally reject an offe,r just explain that you like the offer but there is another that's a better fit right now. This way you kinda leave the door open for a while. We hired people like this who returned to us like you'd like to return now. They were more ready to stay with us like this.
Comment: When I rejected their offers, I explained to them that although I liked their offers I accepted another one that I felt was a better fit at that moment.  Both recruiters told me I could contact them anytime if I wanted to reapply.  So, I guess I just reapply again and see what happens.  Do  you think I should contact them, and let them know I applied?  I normally contact all companies to introduce myself when I apply to jobs, and this has worked wonders for me.
Comment: @TheAccountant You did the right thing by leaving the door open when you "rejected" their previous offer. Moreover, if they explicitly told you that you are welcome to reapply, it means you left with a positive impression. In that case, it is okay to mention it, but (of course, you know this) don't go overboard with it.
Comment: Ok, I contacted one of the HR's managers, and she asked me to apply through their website.  After, I applied, she sent me an email asking me why I left the other job so quickly and what are my salary expectations. I gave her my answers, but she hasn't responded back.  It's been a week since then, so I just think I should move forward and keep looking.
Answer: Simply reapply. They'll probably ask you in the application whether you have applied before, you should say 'yes'. They will probably find that you were a successful candidate, which hopefully triggers some kind of 'welcome back' reaction from them.
If they ask you at your interview why you left, say why you left in a sentence a two - it was a bad experience but they are not asking you to write a book abut it. In one or two sentences about why you left, leave them with a feeling of confidence about your competence  and professionalism which includes your ethics.
In other words, leave the door wide open for them to ask you back in.


Checking If Java Client Sends Emails

Question: Alright so I was wondering if there is a way to find out if a Java client is sending out emails (without you knowing). Like if the client sends an email, or attempts to send an email if you could intercept it or at least find out what is sending that email. Thank you.
Comment: You should link this account with your SO account.
Comment: what do you mean?
Comment: Did you write the client? What smtp package is working? IT sounds like your client is taking over...
Answer: Any good firewall should be able to tell you when an application is sending network traffic such as emails. ZoneAlarm for Windows or ufw for Linux might work for you.
You can see exactly what network traffic is going out from your computer using a tool like WireShark.  This will include any emails sent.
It might not be possible for you to read the email, if it using TLS for example.

Checking If Java Client Sends Emails


Why the result of Random Forest Algorithm change a lot when all the parameters are kept the same?

Question: I want to do some classification of some dataset with random forest. When I run the same script twice, two totally different(almost 5%) result were given by the program. I want to know whether random forest always give the result that change a lot with the same parameters? How can I make it more stable?
Answer: The Random Forest algorithm involves a lot of randomization, as I assume you know (right?). So you will get somewhat different results each time you run it.
To obtain reproducible results, which is a good idea, initialize your random number generator with a fixed number. In R, you can do this with set.seed(1), or with whatever other seed you want.
Be sure to investigate the effects of changing this seed, i.e., how sensitive your results are to your specific random number stream.
Comment: It really depends on your very specific data and its relationship to the outcome variable. If two appreciably different models explain your data about equally well, then any randomization approach will frequently switch between the two models, and the end result may depend in an unstable way on which model was picked how often.
Comment: I used to think that the random can be stabled when a lot of data were feed in to the algorithm, can this be done with a lot of data and proper parameters?
Answer: I was facing the same problem when running the Random Forest code. I wonder if this problem is already solved or not, but I found this source of the latest sklearn's glossary of Random Forest (https://scikit-learn.org/stable/glossary.html#:~:text=value%20may%20be%3A-,None%20(default),-Use%20the%20global).
Based on the source, we should set the "random_state" parameter (0 or 42)in order to make the model reproducible. Otherwise, the random_state will be set as None and the output models will always be different.


Wiener filter optimal coefficients and the input signal

Question: I have this question:
"Show that for the optimal filter coefficients the error $e[n]$ is orthogonal to the input signal $w[n]$."
anybody have an idea?
Answer: For conveniece I'm going to drop the time indexes. Let $e=d-\mathbf{a}^T\mathbf{x}$, where $d$ is the desired signal and $\mathbf{a}$ weights the elements of the observations/input vector $\mathbf{x}$. The goal is to minimize expected squared error with respect to the vector $\mathbf{a}$.
$$\min J=\min E[e^2],$$
where $E$ is the expectation operator.
To find the minimum we take the derivative of the objective function w.r.t. $\mathbf{a}$ and set it equal to zero. Therefore
$$
\mathbf{g}=\frac{\partial E[e^2]}{\partial \mathbf{a}}=E[2e\frac{\partial e}{\partial \mathbf{a}}]=0,$$
but from the defintion of $e$ earlier, we have
$$ \frac{\partial e}{\partial \mathbf{a}}= -\mathbf{x}$$
Therefore
$$ E[2e\frac{\partial e}{\partial \mathbf{a}}]= -E[2e\mathbf{x}]=0. $$ The factor 2 can be removed and thus $E[e\mathbf{x}]=0$, which means the error $e$ is orthogonal to the input signal $\mathbf{x}$.
Answer: In other words,you should show that the expected value of the error term multiplied by input signal is zero.
If you ask about the reason, the linear estimator of the signal that minimizes the error(between the estimator and the signal) is given by the projection theorem and the projection is computed by directly minimizing the mean square error or by applying the orthogonality between error and the input signal.


Visual C++ 2008 Express Edition Wizard work's not correctly

Question: I have Windows Vista, Visual C++ 2008 Express Edition. I'm trying to create a dll. So, I take next steps: File - Create - Project - Win32 - Win32 Console Application (it have to be a wizard). And I was expecting for this window: http://img244.imageshack.us/i/vs3ae4.jpg/ But I've got next situation: http://img30.imageshack.us/i/msvs1.jpg/ It's in russian, but I can translate. The front window tells: "Open or save file?" If I press "Open" my web-browser (FireFox) opens and shows me the web-page: http://img268.imageshack.us/i/msvs3.jpg/ It's like what I was expecting for http://img244.imageshack.us/i/vs3ae4.jpg/, but in the browser, and buttons on this page don't work.
I heard that old version of Java Machine can cause this problem, so I have updated it to the last one. Also I've tried to open this "wizard-page" in different browsers (like Opera or Google Chrome) - the same result. And if I try to open it in Internet Explorer, it asks me again: "Open or Save"... :-/
Any ideas???
Answer: The wizard is based on a webbrowser control, which is subject to IE's security settings. Try reset your IE options.


Why is a bad idea to use a common password form?

Question: I've heard that its a bad idea to create passwords based on a common form such as random letters appended with the start of a websites domain name.  So for example a password to gmail might be something like 8*dfJK3!%kgmail and a password to facebook would be 8*dfJK3!%kfacebook and so on.  Why this considered a bad idea?
Comment: Because if only one site didn't do anything to secure your password, and it's exposed, your system is really easy to figure out and can be used to potentially login to many more sites.
Answer: Reusing passwords across multiple sites is very problematic as a password exposure on one site leads to a password exposure on all of your accounts that used the same password. What you are proposing seems better than using a static password across multiple sites, but it is still rather predictable. If someone discovers one of your passwords they can likely guess many of your other passwords. No matter how careful you are with your passwords, they will be discovered. Sites get hacked and password lists are published.
The only way to ensure password safety is to use unique random passwords that have a provably large entropy (a measure of randomness). This answer discusses randomness as related to password generation.
Comment: To take that one step further:  Passwords don't _need_ to be random, but they do need to _appear_ random to an observer.  Anything that is obviously generated limits the entropy of a password.  In the question, there's a universal password and then a site name.  An attacker with your gmail password will likely guess your facebook password in a single try.  Consider something like [SuperGenPass](https://chriszarate.github.io/supergenpass/) if you want to use a universal password securely.
Comment: I think that tools like SuoerGenPass are not widely accepted @AdamKatz. For example, what do you do if you need to update a password for a site? There's no way to get a second one out of SuoerGenPass.
Comment: Sure there is.  Increment your master password.
Comment: But what about all the sites that you didn't update your password? You'll need to keep track of which sites uses which password? Unpleasant.
Answer: Because it's easily predictable. There was a study done on organizations that enforced a password policy which required every password to contain at least 1 symbol and 1 digit. The results of the study concluded that passwords of the form
<code><phrase><symbol><digit>
</code>
e.g. Example@1
were very prevalent. A malicious attacker can use this to his/her advantage when cracking passwords, drastically increasing the success rate of finding a match.
Comment: But `` isn't really what the OP is proposing.


Magento 2: I am not aware about Magento optimization. Can you please share the steps for this?

Question: I am not aware about Magento optimization. Can you please share the steps for this? How to compete with this?
Thanks
Answer:

Switch your website to production mode

Minify your HTML, CSS and js files.

Merge your CSS and JS files.

Optimize your images.

Enable Gzip Compression.

Ensure if Magento Full Page Cache is enabled. Can install and configure varnish to speed up the site

Do Advanced Javascript Bundling following this link https://devdocs.magento.com/guides/v2.3/performance-best-practices/advanced-js-bundling.html as it will reduce total page size as well keeping the number of requests low

Use the profiler to check files consuming more time. Check and ensure to load them in lesser time.
php bin/magento dev:profiler:enable html
php bin/magento dev:profiler:enable csvfile

Consider Using Google Page Speed Module in your server where you can configure the optimization to speed up the page as well as
increasing your google page speed score significantly. To see if this
can solve all your problems
https://developers.google.com/speed/pagespeed/module/

Enable Flat Categories and Products
Comment: Explained well. +1 for that :)
Answer: The best and easy way to speed up the magneto website is page cache. But beside page cache, you can do the following to improve server response.

Inspect every installed 3rd-party extension, and disable useless extensions on your website
Choose the fastest hosting you can afford
Turn Production Mode On
Never Use JS Bundling

Enable CSS/JS Minification

Last and most importantly, enable profiler and check all the files (.phtml) and events, check which are taking more time to execute. And remember even 0.5 sec for a file or event is also huge time for a single file/event.
Answer: 7 Tips to Speed up Magento 2

1 Inspect every 3rd-party extension installed
2 Choose the fastest hosting possible
3 Make sure Full Page Cache is on
4 Make sure Production Mode is on
5 Never use JS bundling
6 Enable CSS/JS minification
7 Use Built-in Cache, Skip Varnish

For more detail, please visit https://servebolt.com/articles/speed-up-magento-2-in-7-easy-steps/


Phd Application follow up contact the lecturer or the school

Question: After applied to a phd offer in a cluster group in Germany.
I've had a promising phone chat with one professor of the group.  Our research interests are closely related and he told me i will receive a mail from the administration not from him.
The interview went well, he was even querying about the visa procedure. But it's almost 20 days now and i did not received anything. I'm confused.
Should i contact him to ask? And what to write?  As he as warned me that the administration always took too much time.
And i do not have any contact with the administration since the beginning.
Answer: I have been involved in multiple PhD student searchers. Things tend to be rather informal. If I were you I would send him an email inquiring about the status of the application. Keep in mind tho that sometimes things are slow in Academia.


APEX SOQL retrieve values dynamically based on string variable

Question: In my apex code i have a variable resultField and a List<Id> objIds. What i need is a List<My_Obj__c> objs = [select Id, :resultField from My_Obj__c where Id in :objIds];. This is not working because apparantly i can't specify :resultField even though :objIds work in the query. Is there a way to do it other than string concatinations.
Comment: @RahulSharma  i am trying to select a second field dynamically from variable resultField. That's why there is that ,
Answer: You cannot use Apex bindings in the SELECT or FROM clauses of a SOQL query. Bindings are available in the WHERE clause.
You'll need to use Dynamic SOQL to construct your query as a string concatenation, as you mention - there's not another way to build a query with dynamic values in the SELECT clause.
Comment: will it let me do `Database.query('select Id, ' + resultField + ' from My_Obj__c where Id in :objIds')`. Will it let me bind `:objIds`
Comment: Yes. You can still do simple binding to Apex variables.
Answer: Salesforce only takes bind variable in WHERE clause and not in the SELECT statement.
So, you need to perform String concatenation.


How do I "block off" an area with command blocks?

Question: How can I make a certain radius around a command block, somewhere only certain people can enter, even with <code>/tpo</code>. I want the command block to teleport the people who try to teleport inside that radius to be teleported to certain coordinates. Is that possible? If so, how?
Answer: You could do it by TPing all players not in a specified team away.
Add all players that you want to access the area to a team:
<code>/scoreboard teams add [team name]
/scoreboard teams join [players...]
</code>
Then you need a command block in Repeat mode in the area, you can use needs redstone or always active, but I would suggest that you at first run a redstone wire with repeaters and a lever at the end for testing.
Repeating command block command:
<code>/tp @e[r=[range in which players cannot access the area],team=![name of the team that can access the area]] ~40 ~ ~ [you can change the location]
</code>
Example:
<code>/tp @e[r=10,team=!access] ~20 ~ ~
</code>
Comment: Yup, that's just what I was about to suggest. If you don't mind other entities (eg. minecarts, mobs) being in that area, you can use the @a selector instead of @e. You could also use a scoreboard tag rather than a team for this, but there's no real reason to use one over the other.
Comment: 1.13 syntax: `/tp @e[distance=..,team=!] ~40 ~ ~`
Answer: You would need to continuously /testfor the area to see if people are in the specified range, etc.
Then you'd link the /testfor command-block to another which teleports the player to somewhere else.
And the good thing about this, is that even if they teleport-in or walk-in, they'll be teleported either way... or is that what you wanted?
Hopefully, my answer assists you in your endeavours.
Comment: I have attempted stuff like that before, but it never worked for me.


Propagation Constant Expression in a Transmission Line

Question: let's consider a generic transmission line:

Its wave vector Kz is equal to:

where

Then, I read also that it is true that:

where does this relation come from?
Answer:
where does [the] relation [\$k_z=\frac{2\pi}{\lambda}\$] come from?

The variable \$k\$ is used to refer to different things by different authors.
In many texts, \$k\$ (usually with no subscript) is defined as the wavenumber of a wave, i.e. the number of waves per unit length. With that definition,
$$k=\frac{1}{\lambda}$$ where \$\lambda\$ is the wavelength.
In the text where you saw, $$k=\frac{2\pi}{\lambda}$$ \$k\$ is just modified by a convenience factor of \$2\pi\$ just like we use $$\omega = 2\pi f$$.  In that case, \$k\$ is the phase constant for a particular sinusoidal wave. It represents the change in phase angle per unit length.
In the equation $$k_z=\sqrt{(R+j\omega L)(G + j\omega C)}$$ \$k_z\$ is the propagation constant for a sinusoidal wave along the transmission line.
The real part of $$k_z = \alpha + j\beta$$ (i.e. \$\alpha\$) is the attenuation factor. It informs us how much a sinusoidal signal is attenuated per unit length.
The \$\beta\$ in the above equation is the phase constant for the wave under consideration. It is identical to the \$k\$ in the equation
$$k=\frac{2\pi}{\lambda}$$
Thus, when you see in different places,
$$k_z = \alpha + j\beta = \sqrt{(R+j\omega L)(G + j\omega C)}$$
and
$$k=\frac{2\pi}{\lambda}$$
The \$k\$s mean different (but related) things.
Answer: The wavenumber \$k\$ is the result of solving the differential equations of the (general) electromagnetic wave for \$E\$ and \$H\$ in e.g. free space. The result for \$k\$ consists of the material characteristics \$\mu,\epsilon,\sigma\$.
When solving the telegrapher equations for the coaxial cable, you also get \$k\$, but this time \$k\$ consists of an R,L,G & C expression.
So the wavenumber \$k\$ comes either from the definition of a general wave or from the definition of a generic transmission line like e.g. a coaxial cable.
(The phase constant \$\beta\$ is just the imaginary component of \$k\$.)
Comment: But where does the link k= √(YZ) = k = 2π/lambda? Why are they necessarily equal in case of TEM mode?
Comment: @Kinka-Byo I refined my anwer to give you a bit more insight


Dock won't position on the bottom

Question: How do I get the Dock to go to the bottom on my Mac Pro with Yosemite?  It will go on either side, but not the bottom.  It goes on the bottom on my Macbook Pro, but not the Mac Pro.
Comment: Are you using any third party software such as "Onyx"?
Comment: Could you expand what you mean by 'not the bottom'? Do you get any errors when you try this? What is preventing you from selecting the option?
Comment: Have you tried logging out and back in? Do you have multiple displays, with another display logically below the one you're trying to put the Dock on? How are you trying to move the Dock? (Shift-drag of the divider? Dock menu→Position on Screen? System Preferences→Dock?) Maybe try another way.
Answer: You could try to restart your Dock by opening Terminal app in your Utilites folder and running the following command:
<code>killall Dock
</code>
Comment: Repairing Permissions is an utter waste of time, especially in a situation like this where there is no indication of a permissions problem on anything installed as a system file.
Comment: @ganbustein I guess you are right on that! = deleted that part.

Dock won't position on the bottom


question about how to use the electronic pedal?

Question: how to use the sp-3 pedal? do I press on it using the whole foot on it or I just press on the outer side? I bought one but I don't know how to use it?
Answer: Assuming you mean the Casio SP-3: you use it like you'd use a sustain pedal on a real piano. Keep your heel on the floor and press the pedal with the front part of your foot. Those electronic pedals tend to have weaker springs than a real piano pedal, and don't normally give you quite the feel of the real thing.
Answer: It works just like a doorbell push. Press it, sustain, let go, sound stops. Not quite as easy to use as one which looks more like a proper piano pedal, but does the job. Heel on floor, press with toes.
If your piano has a 'half-pedal' facility, then really you need a pedal that terminates in a TRS jack.


N-alkylation of amides with alkyl halides?

Question: Can amides be N-alkylated with alkyl halides? Say I was trying to make N-propyl acetamide. Would iodopropane and acetamide react to form it? Would they react to form N,N-dipropyl acetamide? If so, what catalysts would I need, and if not, why not and how would it be possible?
Comment: Anecdotic evidence is no evidence, but trying to methylate two free hydroxides on a $\ce{C5}$-amide I got full methylation, i.e. on the nitrogen, too. Conditions used were $\ce{Ag2O}$, $\ce{MeI}$ and stirring over the weekend at room temperature.
Answer: Sure, there are a number of ways to do this with copper, iridium, or palladium catalysts.  This link should hopefully be helpful.
http://www.organic-chemistry.org/synthesis/C1N/amides2.shtm
Answer: The amide nitrogen is not a good nucleophile to react. But it can become nucleophilic in the form of $\mathrm N^-$ as a conjugate base of a weaker acid. This means that you need a strong enough base to deprotonate the amide. Some standard conditions are NaH in THF or DMF, or n-BuLi, LDA and the like in THF/ether etc.
Answer: I've read of several related sn2 reactions. Generally the procced via an alkyl bromide, I2 catalyst and CsCO3 to drive the reaction to the right.
They all seems to be sensitive to the solvent employed. Many solvents seem to work, but the difference in yield can be very large.
From CH2Cl2 to CH3OCH(CH2) to formamide. I presume that the solvent system is the key and thus within the sphere of chemical engineering.
Answer: A better route could be to form the alkylated amine first and use an activated carbonyl group such as an anhydride or an acyl halide.
Although stericly hindered, the amine should react with good yield to form the amide.
There is a good chance a primary amine could simply be reacted with carboxylic acid under heat to form the amide, especially if reaction water can be drawn off, and even a secondary amine would be worth a try.


If angels cannot reproduce, then why did God castrate the angel Samael?

Question: It's a common belief that angels are incapable of reproduction, if that is so then why is there a story about God castrating the angel Samael, he wouldn't need to if angels cannot procreate.
Answer: The answer is given in the very quotation you cite:  in that tale, angels can indeed procreate, and have "demonic offspring."
Tales frequently are inconsistent.
Comment: "Tales frequently are inconsistent." This bears repeating---in general, not just on our site, where it seems to answer a decent number of questions!
Comment: @Mary so the belief that angels cannot reproduce is a more modern tradition?
Comment: No telling.  There's a lot of inconsistency in the same time period.
Answer: As Mary's answer has already said, angels often are portrayed as capable of procreating.  The origin of the Nephilim in Genesis is an example of this explicitly stated in the bible, if briefly.  I wanted to add an answer to expand on the idea that angels can't procreate and where this comes from.  Modern Christian dogma often takes it for granted that angels are sexless.  This seems to derive largely from Matthew 22 where it is said that there will be no sex and marriage in heaven.  However, the logic behind it also has to do with the way that our view of spiritual entities have changed over time.
Many modern Christian groups will insist that angels must be genderless because they are "pure spirit", as if spirit is non-material and therefore can't be associated with forms.  This isn't really the way that ancient people looked at spirits though.  Spirit was "subtle matter".  It was something different than the vulgar stuff of the physical world, but it was still stuff.  Spiritual entities in the ancient world had bodies, wore clothes, ate food, etc.  Even the above mentioned passage in Matthew frames the lack of marriage in heaven as being due to the fact that we will be given new, purified bodies with different sets of needs, not due to the fact that we will be naked souls with no bodies.
Angels in the Old Testament have sex and come over for dinner and get into wrestling matches, and they also manifest as unknowable cosmic horrors that can't be approached or understood and make people fall on their face.  There was no contradiction in these perceptions of spiritual beings in the ancient world.  A combination of platonizing influences and modern rationalism, however, have resulted in a clean break between the physical and spiritual that makes such fuzzy lines untenable to many modern believers.


mysql select search takes too long to display if queried with Excel

Question: I am quite new at MySQL so please bear with me...
I have an excel sheet which queries a MySQL database...here is part the query (run from VBA macro):
<code>...
    sql_query = "SELECT SQL_CACHE g.Id, g.Client, g.text_parsing FROM `global`.`tbl_cots` AS g  WHERE g.Client LIKE '" & strClient & "%' GROUP BY g.Id;"

With rsPubs

      .ActiveConnection = oConn
      .Open sql_query

    ' Copy the records into cell A5
    Range("A5").CopyFromRecordset rsPubs
...
</code>
The database has 1.3 million rows.
When querying a certain client (14000 rows found) takes some 10 seconds to display...
If matching records is a small number, it displays faster (<2 seconds)
I take it then, that the higher the number of records returned, the longer it takes to display.
However if I run same query (14000 rows returned) with MySQL Query Browser, the 14000 records are shown instantly.
Any ideas how to make VBA query run just as fast or is this one of the limitations of using Excel/VBA to query MySQL database directly?
I am rather confused as Inserting via VBA (from excel) I manage to insert >10000 records in 2 seconds....I can't understand why SELECT takes so much longer to run...
p.s. field 'client' is indexed
Thanks in advance
UPDATE
I was accessing the database via IP (to simulate access to database from 'outside/remote').
Changed DNS to localhost and fetched results almost instant.
So...is there a way to speed up the SELECT when database is accessed remotely ?
Comment: The select takes longer because it has to filter out a lot of records to match your where clause parameters.  Nonetheless this is quite a hefty task to be doing through excel.
Comment: I thought that the purpose of fields being indexed is so to make 'filtering' faster ?
Answer:
When querying a certain client (14000 rows found) takes some 10 seconds to display...
If matching records is a small number, it displays faster (<2 seconds)

The query will run at the database in the same time no matter what program/tool is sending the request. However, most DB Query applications such as Toad or SQLDeveloper will only return the first xxx number of rows. Your VBA code will require the entire dataset to perform the update, hence it takes a shorter amount of time with a smaller resultset.
VBA is generally terrible in terms of speed (not to mention a CPU HOG), so I would suggest that you try to do all your heavy number crunching in the SQL itself and try to return as few rows as possible. By that I mean if you are returning a bunch of rows to excel, then running them through a pivot or the like to aggregate them, you would be much better off doing the aggregation at the database and returning the smallest dataset possible.


Difference between Solana pay transaction request and transfer request?

Question: could anyone explain me what is difference between transaction request and transfer request . I've seen in transaction request we are sending back a transaction to customer to sign and approve .And In transfer request we are just sending an url containing the transfer rquest.
Answer: Not all transactions are transfers.
In transaction request, A Transaction is created like for example minting a NFT and any possible tx on solana. This transaction is read by wallet's then they parse the transaction and ask's the user to sign it from their phones.You can better understand it's working and implementation from this docs here and transfer request's are simply used to transfer x amount of SOL or SPL tokens from user's account to a merchant account. Transfer requests are kind of subset of Transaction requests.