According to Classical Theists, is God limited by the laws of logic?

Question: I was pondering this question while writing on whether or not God had the ability to create a best of all possible worlds. I hold that God is not limited by anything (a view among classical theists such as myself). But I also hold that God can't do things such as make a rock so heavy he can't lift it, or he can't make a married bachelor, due to the laws of logic, such as the law of non-contradiction. So is God limited by these laws of logic?
Comment: Does my answer to this question answer your question as well? https://philosophy.stackexchange.com/questions/90027/how-can-an-omnipotent-god-ever-find-out-that-he-is-omnipotent-isnt-it-logicall
Comment: When God is spoken of as El Elyon or El Shaddai, do we mean *all* power or *maximal* power? According to the Stanford Encyclopedia of Philosophy, IIRC, there has been a drift towards the maximality definition of omnipotence in recent years. Then we just say that the cardinality of the set of God's powers is greater than the cardinality of the set of any creature's powers, irrevocably. This does not require e.g. that God has the power to ejaculate semen, or other such 'debased' things.
Comment: Like all concepts, also the concept of god has been created by humans. Theologians elaborate on this concept since thousands of years. In particular on two topics: - How to define the concept? Which properties characterize a god? - Has the concept a referent? Does there exist a being with the properties from the definition? The OP's question "is God limited by these laws of logic?" refers to the first issue: The paradox of omnipotence shows the problem when taking omnipotence as part of the definition: Assuming that a concept has a referent and at the same time placing the possible referent ou
Comment: @Geoffrey Thomas I have edited my answer. Then you converted the edited answer to a mutilated(!) comment. That's not what I intend with editing my answer. Why not leaving the answer as it is after editing? Do you consider the answer of low quality or out of focus?
Comment: In a comment on the answer from @tkruse you said you weren't asking if God can do certain things (presumably, whether He can 'violate the laws of logic'), rather you were "asking about God's nature in relation to the laws of logic". It might be helpful to include this in the question, and to elaborate on what that question about God's nature is, specifically--are you asking only whether classical theists would see it as God being "limited" by something external to Himself (the 'laws of logic'), vs. seeing the laws of logic as part of God's nature? Or is the question not just about that?
Answer: Many, if not most classical theists think so. Aquinas solved a lot of "problems" by citing God's logical nature as being the ontological source of things like the law of non-contradiction. God not being limited by anything is a somewhat separate issue, but many classical theists (for example, William Lane Craig) would argue that God's limitations are not limitations in the normal sense of the word (as in, he's limited because he can't make a rock he can't lift) but rather logically incoherent statements that can't be spoken about as actions at all. Another way a classical theist might think about it is that God cannot act against his nature (law of identity), and because God's nature is to a classical theist the ultimate reality, God acting against his nature is both a logical impossibility and an incoherent statement.
Comment: @LukeHill If you mean what I think you do, that sounds right. A classical theist (I am a thiest, but I don't hold this view for some reasons I won't get into) would say that to talk about God being limited by the laws of logic is itself illogical, and is something of a category mistake.
Comment: So perhaps it's right to say that God is not limited by such, but that God's nature is that which is logic.
Answer: Our ideas of logic is limited to what we have experienced. Some things might seem like it would defy logic, but we haven't experienced enough knowledge to understand an answer. For example, many people thought the theory of relativity defied the laws of logic (and physics) in many ways. But there was a way around it using ways not yet thouht about.
Also, if you believe in God, you must believe in many things about him that seem illogical.
Comment: While this isn't really what most classical theists believe, this is a great insight that is worth reading anyways.
Comment: People often use "logic" loosely to refer to something more like "reason", to claim laws of logic are violated you should to be able to actually write down the premises in some kind of formal logical language like propositional logic, and show using standard rules of inference that they can be used to deduce a contradiction. I don't think most atheists claim typical ideas about God are "illogical" in that sense, and I don't think most critics of relativity would have said it was illogical this way either (unless they might use some incorrect premises to get a contradiction in the twin paradox)
Answer: The Wikipedia article on omnipotence explains most of the subtleties, writing classical theists: https://en.m.wikipedia.org/wiki/Omnipotence

In response to questions of a deity performing impossibilities, e.g. making square circles, Aquinas says that "everything that does not imply a contradiction in terms, is numbered amongst those possible things, in respect of which God is called omnipotent: whereas whatever implies contradiction does not come within the scope of divine omnipotence, because it cannot have the aspect of possibility. Hence it is better to say that such things cannot be done, than that God cannot do them.

The possible paradoxes are also well explained in Wikipedia: https://en.m.wikipedia.org/wiki/Omnipotence_paradox

The paradox arises, for example, if one assumes that an omnipotent being has no limits and is capable of realizing any outcome, even a logically contradictory one such as creating a square circle

It is also well hashed through in prior questions of this forum, such as Can God make a rock so heavy he cannot lift it?, Problems with the Omnipotence paradox, Does this explain the Omnipotence paradox?, Can someone explain omnipotence to me?
... It does not seem the current question brings anything new to the table that a quick Google search could not solve.
Comment: Notice that my question was not one of "can God do X?" Rather, my question was asking about God's nature in regards to the laws of logic.
Comment: It seems to me that those are related enough that the resources i list should help you find whatever you're looking for.


Writing usb on FreeBSD to access on windows

Question: How can I write "stuff" into USB drive on FreeBSD such that, the "stuff" is accessible in Windows [yes my wife still uses that :( ] and Ubuntu?
Answer: Windows can only mount FAT variants and NTFS natively. Non-native filesystems exist but require going through hoops to the point that it's often simpler to install a Linux (or FreeBSD) VM. So, pick FAT32 or NTFS.
The FUSE NTFS-3g driver is available on FreeBSD as a port (fusefs-ntfs), as are the associated utilities (ntfsprogs).
Answer: Sure. Just format it with newfs_msdos (you can even format whole drive, without any partitioning scheme).


Private VLANs Same As VLANs!

Question: The common VLANs provides a layer 2 speration flooding and broadcasting is limited to each virtual lans.
Im wondering what is the purpose of the private VLANs also the secondary VLANs (isolated and community) since the known vlans already provides the isolation and some HSRP or VRRP vlans can be used in uplinks same as community i mean what is the additional features that it can give!?
Thanks in advance.
Answer: Private VLAN is a feature that prevent hosts within a single VLAN to communicate with each others.
VLAN separate different networks.
A site may consists of thousands computers, belonging to dozens of business unit or department, segregated by different VLANs. One VLAN for the accounting department, one for human ressources, one for IT, etc...
Each VLAN corresponds to an IP network, and access control lists (ACL) control what the hosts on those VLAN can access. I.E. the users in the accounting department can access some servers while the other user can't, etc...
Now two clients computer in a given department have no need to communicate together, and this is a security liability. If a virus infect a computer it can exploit a vulnerability in a network protocol to infect other computers. Private VLAN prevent this.
You can't possibly isolate each single host in this own VLAN. It doesn't scale to more than a few computers. This would be an administrative nightmare, and is anyway limited to 4095 hosts.
So VLANs give a nice way to group hosts that have the same functional role and security requirements while private VLAN give an easy way to block unwanted communication between hosts in a VLAN.
Answer: Basically and by default different VLANs won't communicate with each other . And same VLANs host will communicate to each other . Traditional to restrict traffic among same VLANs host àccess-list can be configured restricting access among same Vlan hosts . Private Vlan is open standard protocol used alternative for access-list to restrict and allow tràffic between same VLANs
Basically different VLans won't communicate with each other to make them talk to each other Inter -Vlan routing need to be enable . After enable inter-Vlan routing different VLANs will talk to each other to restrict traffic or control traffic among different Vlans host private Vlan concept is used .

Private VLANs Same As VLANs!


Help get me a grand piano Hi Gloss Finish please

Question:
Hi everyone
My carpenter friend has made me this mini grand piano shell for my one keyboard and I want to get it painted or sprayed like a grand piano finish.
I'm a complete novice here and need every assistance like what paint to use? Do I want an epoxy resin etc
Any help really appreciated and thanks in advance.
Answer: I have used a water white conversion varnish for years with very excellent results.  it must be applied with a sprayer and dries very quickly so multiple coats can be applied.  I get my sprayer gun at harbor freight for $10-$14.  Conversion varnish is a catalyzed product that can easily be buffed out once it is cured.  Check out Lenmar Megavar.  Excellent stuff.  Once cured, use a buffer with 3M Perfect-It 05973.  Epoxy would be impossible to apply to vertical surfaces and it's much more expensive. I believe you would be well served by using this process.


Fell down [in/on] the runway

Question: Which one is correct: The fashion model fell down in the runway, or on the runway?
Answer: "On" is the right preposition for things happening in relation to the surface of stages, platforms, tables, floors, and the like. A runway is an elevated platform, basically a stage that extends into an audience area. The model was "on" the runway. This runway might might have been in a theater, auditorium, tent, or studio, but she was on the runway.
Note that things can also happen by, at, before, across, above, below (and more) with respect to a stage or table. But in regard to placement in contact with a surface, "on" is pretty much always right.

Fell down [in/on] the runway


What is the purpose of the Call Stack window in Visual Studio?

Question: What is the purpose of the Call Stack window in Visual Studio?
Answer: When your code breaks (i.e., when an exception is thrown) the Stack Trace Window will show you all methods that have been called prior to the method that raised the exception, including the parameters for each method and the state of these parameters. This makes debugging easier, especially in more complex call graphs (that is, when you cannot determine by looking at your code who called what other method/property/function).
Just try it, place a breakpoint somewhere in your code (F9), run your code, wait for the breakpoint to be hit and then open the stack window. You'll see all calls up to the current line. You can double click each entry in the stack trace window and the cursor will jump right at it.
In case you wondered: gray lines are method calls of which no source code, or symbols are loaded. You can rightclick these lines and select Load Symbols to load the symbols.
Answer: Each time you call a method, an entry is place on the "stack" for that thread describing the method and the parameters used to call the method. When the method returns, the method and it's parameters are removed from the stack. That's how the operating environment knows where to return when a method finishes. It just removes the top entry from the stack, cleans up any local variables that were created during that stack frame, and returns to the previous method. (That's over simplified, but generally the idea.)
You can think of it literally as a "stack" of the instructions that got you here.
That's what it means to the operating environment.
To the developer, the practical purpose is to help you understand why your program is in the state it is in. Whenever execution of the program stops in the debugger, either by breakpoint or by an exception being thrown (depending on your Visual Studio settings), you will have access to the current stack. Remember that this stack doesn't show ALL methods that have been called up to this point. Any method that completed was removed from the stack. It's not a log.
You can double click on any of the entries in the stack to go to that source code (if it's available on your machine). While you're there, you can inspect local variables, etc. It's a kind of detective tool to help you figure out what has happened in your program up to this point.
Answer: The purpose in the call stack is to allow you to see exactly what call caused an issue to happen.
When you look at the stack trace in an Exception, you can see the original call that caused the error to happen.
When debugging in Visual Studio, you can navigate up and down the call stack to see what values your application is storing at different levels. It's useful in debugging how your application got to the state it is in.
Answer: The purpose of the call stack window is to provide you access to the full code path which got you to the current instruction.  You can use it to navigate to previous function calls within the program, inspect local variables, parameters, etc ...  It's an invaluable tool for determining why your code is doing what it's doing.


Any editor as convenient as that of stackexchange Physics

Question: Stackexchange physics has a very nice real-time editor of latex form formula.
Writing notes in this editor apparently is more efficient than using a normal latex editor.  Is there any similar project online or as a software which allow
me to save edition and write in  A4 size pages ?  As writing notes, the full feature of latex is not that important.
Comment: Welcome to TeX.SX! Please specify what you mean with "save edition".
Comment: I mean as I type in the stackexchange editor,  By clicking, I can only post it. I cannot even save it as a draft. Anyway,  I can copy the text to a local text editor then save it.
Answer: As I understand it, Math SE and Physics SE calls mathjax server, so that they can be previewed in real-time. I suppose (correct me if I am wrong) doing this on local machine is both time-consuming and unnecessarily resource-wasting. Indeed, it may not be a good idea to auto-compile for every few seconds, as you may still be drafting something incomplete, and compilation errors are abundant.
I am satisfied with TeXstudio, where I write on the left and see compiled pdf on the right. I think this is convenient enough. Actually I am recently starting using Vim exclusively, and compile on command line whenever I see fit.
If you use Mac and really want a quasi-WYSIWYG editor, you may try TeXmacs. If you use Windows, do you consider MathType?
If you would like editor to save your work every once in a while, there are many software that does this. TeXStudio has backup options; see preferences. Even TextEdit and Vim has auto-backup options. I am afraid this particular point is not relevant to this site.


archive files and directories before transfer

Question: I was wondering what is the advantage of making all the files and directories into an archive file for transfer, such as by cpio, instead of transferring them directly, such as by cp, scp?
Answer: There are a few reasons you might want to tar up a bunch of files before transfer:

Compression: You will get better compression by compressing one large file rather than many small files.  At least scp can compress on the fly, but is on a file by file basis.
Connections: At least with scp, it makes a new connection for each file it transfers.  This can greatly slow down the throughput if you are transferring many small files.
Restart: If your transfer protocol allows restarting a transfer in the middle, it might be easier than figuring out which file was in progress when the transfer was interrupted.
Permissions: Most archiving programs let you retain the ownership and permissions of files, which may not be supported in your transfer program.
File location: If the destination location is at the end of a long path, or hasn't been decided, it might be useful to transfer an archive to the destination and decide latter where the files should go.
Integrity: Its easier to compute and check the checksum for a single archive file than for each file individually.
Answer: I do this because its often easier to handle one big file, then thousands of small chunks.
I don't have to calculate checksums for every file, most of the time it is enough to just create a checksum for one archive.
Also it is easier for me to preserve file permissions.
These are just some of my reasons.
Answer: If using rsync is possible, the advantage of archiving first is almost gone.

Compression: rsync has built-in compression (option -z).
Connection: The number of connection (generally 1) doesn't increase with the number of files transfered.
Restart: rsync only transmit the difference, so incremental transfer is simple. You can choose to keep partial files so it is faster to resume the transmission.
Integrity: Check-sum is used internally, and if you are paranoid about it, you can force the -c option, so it is checked again.


Transfer ownership of a Google My Business page without account access

Question: How can I transfer ownership of a Google My Business page without knowing what account they are linked to?  We have acquired companies and have no access to the Google accounts.
Answer: From https://support.google.com/business/answer/4661508?hl=en

Resolve owner conflicts
Each location on Google can have only one verified owner. If you see
the status "Different owner" in your account, this means another owner
has verified this location on Google.
When you add a location that matches a live location with a different
owner, it is treated as a duplicate and will be ignored when importing
your spreadsheet.
You have several options to address this issue:

Check within your organization to see who you may need to coordinate with, including agencies your company may have hired to
manage on behalf of the business. Learn more about how to share
ownership of a set of
locations.
Request management if you'd like to request a transfer of ownership from the current owner or to be added as a manager. Learn
more.
Remove the location from your account if you'd like the current owner to continue to manage the location. Learn
more.
Leave the location in this state if you only use it to run AdWords location extensions. Learn
more.

If you claimed the location with a different account and have
forgotten that account's username or password, visit the Accounts
troubleshooter
to get help.


Linking a research publication in CV

Question: I authored a research paper with a group for an internship last summer, which can be retrieved online. Is it worth providing a link to the paper on my resume, or is this unnecessary and a bit superficial? I also listed it as my only publication in a section for "First author publications." Is this necessary to do if this is my only publication?
Comment: Where is it - a journal website, the company or department you interned with's website, someone else's research page, arXiV? I'm guess I'm asking can you describe where to find it rather than just giving a link. Will you be delivering the CV electronically, i.e. where the reader can just click the link, or on paper where they'd have to type it in?
Answer: I think it is a good idea to include a link in the version of your CV that is likely to get read electronically, such as from your website or from an email.
However, you could put a small icon or short text to click the link, instead of showing the complete URL. This saves space, looks neater, and anyone who does not view your CV on a computer would likely search for the publication directly instead of typing in an URL, so that is unlikely to be of much use.
An alternative option is to mention a single source where all the papers can be found (such as Google Scholar, or your website) at the top of the section, optionally with a link, instead of providing links for individual publications.
For the second part of your question, just naming the section "Publications" should be sufficient, since the author list would be shown anyway, and you are not filtering your publications to a small strict subset where you are the first author.

Linking a research publication in CV


Creating a map of a planet with a strange shape? (edited)

Question: I have a planet that has an odd pull of gravity because it's shape is an amalgamation of large landmasses merged together, and held in place by magic forces. Aside from the fact a shape like this on a planet is hard to rationalize, it's also difficult to imagine how you would map this planet out on a flat surface. how would you draw this on a map?
Comment: Welcome Moose. What's the actual question? Please take our [tour] and refer to the [help] for guidance. It helps us to answer you if you make it clear what the question is.
Comment: (a) Mapping software is listed on our [list of Worldbuilding resources](https://worldbuilding.stackexchange.com/q/143606/40609). However, (b) there won't be one for an arbitrary 3D shape. You'll end up compromising on the shape vs. your ability to comprehend the shape. However, I suspect that if you deal with it in portions, you'll do alright. (c) Finally, it should be noted that the nature of gravity (unless the planet is airless) is to wear everything down into a sphere. Your world must be very, very, very young to have this shape. Even if assumed, its spin would tumble something awful.
Comment: Welcome Moose! The answer will depend on context. Do you want to describe that kind of mapmaking in a story, or do you need help actually making the map? If it's supposed to be an in-universe map, what level of science and technology do your fictional mapmakers have access to? What kind of art style do you want? I would recommend adding more details so we can help more. Also, it seems you aren't interested in the physics of why it's that shape, so I'd remove the geophysics tag, and ask people to disregard the plausibility of the situation.
Comment: @JBH: Airlessness has nothing to do with it. *Any* sufficiently large body will be more-or-less spherical -- it's called hydrostatic equilibrium.
Comment: Is your planet really so small as to have such a weird shape? A radius of 500 km or so is sufficient to make the planet spherical. (See [Ceres](https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)) for an example. Note that with a radius of 500 km, the surface area will be 160 times smaller than Earth's, and the gravitational acceleration on the surface will be wavy-hands about 12 times smaller than on Earth. Ceres is made of lightweight materials, so that the surface gravity is only 0.029 *g*.)
Comment: I would be looking into: How do I map a texture onto a oddball shape. Ie this is a kinda solved problem of 3d artists that are putting pictures/textures onto 3d objects. I say kinda cause it is easy to get distortions.
Comment: What is the question?
Answer: The "geophysics" tag necessitates a "frame challenge," which is a challenge to the premise of the question. If you have vaguely realistic physics in your setting, a planet that is as far from spherical as your drawings indicate can't exist.
The reason for this is simply that rock is not rigid enough for this planet to hold its shape. It will collapse, quite quickly, into a close approximation of a sphere. It won't be a perfect sphere, but it will be pretty close, as the earth is.

Earth has continents and oceans because it has two separate types of crust, called "continental" and "oceanic". Continental crust is less dense, and thus floats higher on the underlying mantle. It's all a matter of density and buoyancy: the apparent rigidity of rock on a human scale is irrelevant, because it isn't strong enough to resist the pressures within the earth, and behaves like a (pretty stiff) fluid.

The exact shape of the Earth is a bit complicated.

Its radius at the poles is about 0.3% less than at the equator, so a slightly flattened sphere is a good approximation. The reason for this distortion is that it spins quite fast, and is stretched, a little, by centrifugal force. If it were to stop rotating, it would slump back into a much more spherical form, involving a world-wide earthquake of unprecedented strength.

The earth's gravity field is not perfectly uniform, because its density doesn't increase uniformly with depth. There are some areas where gravity is a little stronger and others where it is a little weaker. The effect is far too small to notice with human senses, but is detectable with precise surveying instruments. The mathematical approximation of the earth's gravity is called the geoid.

A small enough planet will not collapse into a sphere, but that limits you to bodies too small to retain a significant atmosphere.
If you want an irregularly shaped planet, you're going to need different laws of nature, or technology advanced enough to manipulate gravity on a vast scale. When that goes wrong, the planet will slump into a sphere, destroying everything on its surface in the 'quake.
Comment: Throwing magic in completely changes your question and pretty much means the geophysics tag is not appropriate.
Comment: fortunately, there is magic keeping our planets shape intact. it's a whole natural history thing, but there are beings before humans that had come and shapen our planet
Comment: @Mooseofthemoss: If there is magic keeping the planet in shape, you should say so in the question, and remove the geophysics tag. We can't read your mind, and Worldbuilding gets used for SF as well as fantasy worldbuilding.


Why did the Russians lose to the Turks in 1711 after defeating them in 1700 and the Swedes in 1709?

Question: The Russians captured Azov and Taganrog in a war with Turkey that ended in 1700. Then they decimated the Swedish army at Poltava in 1709, thereby crippling their main enemy, and freeing the bulk of their forces for action against any enemy, including Turkey.
The Russians were "on a roll" by 1710. How and why would they lose Azov and Taganrog to Turkey so soon after winning such victories? Or did these victories make them overconfident?
Conversely, if the Turks won, it didn't seem to have done Sweden or its King, Charles XII, any good (given the ending of that war), even though they were allies of Turkey. Why is that?
Answer: Peter greatly underestimated the size and speed of the Ottoman army, overestimated his chances to peel away Ottoman vassals as allies, allowed his supply lines to be disrupted, and misread the terrain and Ottoman maneuvers, bogging his forces down in a marsh.
This should have been the end of Peter the Great, but his reputation and the timidity of the Ottoman general Pasha Baltadji meant he escaped with a negotiated peace instead of capture and the complete destruction of his army.
Answer: My cousin-in-law, Professor Viktor Ostapchuk of the University of Toronto might be willing to help you with this. The following is what I know about this sad time in Ukrainian history:
Tsar Peter's marketers had just come up with the concept of "Rossiya" to justify Moscow being the capital of ancient Christian Kyiv-Rus'. Moscow was supposedly the "Third Rome" & a treasured ikon stolen from a monastery just north of Kyiv was renamed the "Vladimir Ikon" & kept in Moscow for use in religious justification of its rule. The murder of tens of thousands of Rus'- Ukrainians at Poltava, Bili Tserkva (White Church), and other conquered lands drove most Slavs away from fighting on the Muscovite side. The descendants of the Kozaks, to this day, identity as Rusyns, not Russians.
Since that time, free Rus' Ukrainians will form alliances with Moslems and others fighting Moscow imperialism. So this battle continues in the 21st century.
The battle over whether Moscow is worthy of being a capital of Orthodox Christianity continues as well. Tsar Putin seeks to conquer Kyiv, without which there is no empire of "Russia", & also continues the propaganda war against the Patriarch of Constantinople. Telling that Putins spiritual advisor is on the Holy Mountain, not in "Russia," and that Putin is never seen receiving Holy Communion in an Orthodox Church. Since Putin started visiting the Holy Mountain, many monks began rebelling against the Ecumenical Patriarch, more evidence that the wars of 1709-1711 never ended.


What are ways I can analyze malware in an infected machine, not just clean it?

Question: I often run into infected devices in  my environment and would like to learn more about the specific infections that have gotten in. What are the best tools and techniques I could use to do this? I was thinking of taking an image of the device and creating a virtual machine so I could run tests, kill it and create a new infected vm from scratch.
Answer: Malware analysis should be done in a VM preferably disconnected from the Internet.  This is mainly to protect your system, and stop it from spreading (if the malware has that capability).  You can also use snapshots, or sometimes you can setup a VM to never keep state.  VirtualBox is free and will do the job.  VMWare Player is also free, but limited.  Doesn't allow the use of Snapshots unfortunately.
There are various tools out there to help you with malware analysis.  Being disconnected from the Internet can sometimes stop the malware from executing its malicious code.  There are a couple of sandboxing tools that will listen on ports, and respond to network requests appropriately in order to coerce the malware into continuing its operation.  The one recommended by Practical Malware Analysis is FakeNet.  With FakeNet you can even design custom responses to proprietary protocols, and/or non-standard ports.
Cuckoo Sandbox is an open source tool that can provide analysis reports on the malware during its operation.  It can track system calls, keep copies of files created (even if they're later deleted) by the malware, and give memory dumps of the entire system.  A very powerful tool.
Most malware is packed so you'll want to make sure that you can unpack binaries, extract resources, etc.  UPX is the most common.  CFF Explorer is pretty handy for analyzing resources, and includes a UPX utility.  You might want to checkout these 5 tools recommended by MAMB.
These tools will give you a great look at what the malware is doing on a system.  However, if you need to get down to the gritty details you'll want your ever popular IDA Pro.  This is mainly for more complicated malware that you can't coerce into running.  Some malware will start up in suspended threads to run later.  Some just know that you're not connected to the Internet via their own checks.  So you'll have to depend on the disassembly for figuring out what they're trying to accomplish.
Other tools that are helpful, debuggers.  Windbg or Ollydbg are the two most common, but there are lots of options.  Allows you to attach to the piece of malware while its running, set breakpoints, inspect memory, etc.
Answer: You could take a memory image with Moonsols DumpIt and analyze the image with Volatility. You can also use Mandiant Redline to collect a memory image as well and perform some generic analysis of what could be bad.
If you have a tap or span port setup you could go back and analyze the packets if you were doing full packet capture.
You could use sysinternals tools like autoruns, process explorer and process monitor to get a quick idea of what is going on.
Once you are able to isolate the malware you could copy that off and run it in a sandbox like malwr or in a safe VM like you mentioned.  I would recommend checking out the book Practical Malware Analysis on how to safely setup a VM and what tools to use for both dynamic and static analysis.


Can I move air masses with sound waves?

Question: I know I can move air with a fan. Could I move air with sound waves. If yes, how exactly? would it be more efficient? What setup do I need?
Answer: The answer is: not much.   The usual analogy is waves at the beach.  You can see a long line of waves rolling towards the land, but the water never actually moves across the land.   Waves, whether water or sound,  transmit energy by passing it along from one particle to the next.  The medium itself oscillates but doesn't really go anywhere.
There are exceptions such as the shock wave from a bomb blast -- or the puff of air from a gun -- but I'm guessing that's not what you're after here.
Comment: I guess the analogy is not good enough waves on beach are not purely longitudnal
Answer: It likely depends on several things:
the wavelength of the sound -- if the sound is of very, very long wavelength, we call it wind.
The physical environment.  Waves traveling close to the jetty are magnified as they approach shore.  Microwave antennas and trumpet horns are designed to direct and modify the sound energy.
And, according to none less than Nikola Tesla, (https://en.wikipedia.org/wiki/Tesla_valve) a geometry like this valve might just do the trick.
Answer: Sound waves are changes in the pressure density of air. In other words, the air is already moving. A fan makes a sound when it strikes air because it's forcing it together and then it rebounds into adjacent air which undergoes yet another compression and expansion.
Comment: This is not an answer.
Answer: Actually no because to set up a sound wave you push on some particles and they in turn push adjacent particles.So all you can try is pushing the first set of particles harder,but eventually they will collide with adjacent ones.So you ending up producing oscillations instead of collective motion.
Answer: Sound is longitudinal waves.
We could design a structure with many micro holes to allow air flow in one direction (like heart valve).
When sound travels in the air, the air vibrates into the hole and cannot flow back, thus wind is created.
I believe ultrasonic sound (100kHz) would have an observable effect.
I am concerning about the efficiency of such device.

Can I move air masses with sound waves?


Frame expert system

Question: What's the best way to write a simple frame-based expert system, which determines if object is relative to some group? It's a kind of lab work for Intelligent Systems course in university. Or are there any OpenSource projects to study it's realization?
Answer: We used LPA's Flex which is a toolkit that sits on top of win-prolog.  It does frame based expert systems and they have an education programme.

Frame expert system


Set initial robots.txt restrictions so high, Googlebot won't even try to access the updated less strict file.

Question: When I initially setup my blog I put the restrictions on robots.txt way too high. They were so stick that googlebot can't even access the udated less strict robots file. I've been at this problem for days, I'm in a bind. I will be extremely grateful if someone could help me out.
Comment: How many days have been passed?
Answer: I'm not sure I 100% understand your question (you should add a snippet of your robots.txt rules to get a definitive answer)
Sill, from what I read here you must have a <code>"Disallow:\"</code> rule inside which you'll need to remove. I`m saying this because you robot.txt is always should be in root directory and this is the only rule that can prevent access to that (not including wrong syn-text of course)
Also, before doing anything, go into Google Webmaster Tools and use "Fetch as Googlebot" (under "Health") to find out if indeed your robots.txt is as inaccessible, as you think it is.
GL
Comment: I'm wondering if OP set a massive crawl-delay?


R: How to convert graphNEL object into Adjacency Matrix

Question: This is my graphNEL object
>mergedPathways_d
A graphNEL graph with undirected edges
Number of Nodes = 41
Number of Edges = 102

I have tried coerce. It did not work out.
It asks to pre-define the matrix and To and From didnot work correctly, I had NA as entries in my adj matrix
I tried using edgeL. It did not work out.
The edge list I got had numbers as edges and not the names of the genes. And I don't know how to map genes onto those numbers.
I tried converting it into igraph using igraph.from.graphNEL and then using as_adjacency_matrix. It did not work out. I got a dgCMatrix and not a normal matrix with accessible rows and columns and I am unable to convert it into a data frame either.
So right now an adjacency matrix (41 x 41) with rows ans columns being 41 gene names from the graphNEL object. OR an edge list with 2 columns and 102 rows. Each edge on one row.
Any help would be highly appreciated. It has been whole day trying to extract data from KEGG and now trying to manipulate into desired form for further application.
Thanks!
Answer: Have you tried:
as(mergedPathways_d, "matrix")


How to add an image as a single key frame

Question: I am working on a 2d animation in which i had to import images from photoshop in order to create moving bg. I am importing image as planes, but it's applied to entire timeline. I want it to be applied to a single key frame. What should I do?
Comment: If you don't need to animate in 3d scene, you can animate 2D in blender's Video Editor too.
Comment: you can animate the image visibility in the Outliner, put your cursor on the camera icon and press i to create a keyframe, then next frame click on the camera icon and press i again
Comment: If you have a sequence of images you want to display in order, one image per frame in the animation, you can convert your sequence into a movie format "Images as planes" supports, such as mp3; enable "Images as Planes" in preferences; and import the movie using "Images as Planes".  If you edit the material for the plane you can set playback options.  If you don't have other tools to make a movie, you can use the VSE as @vklidu suggests to create the movie from an image sequence.
Comment: Having similar problem..do you found the way to do this?
Answer: I had a kind of similar problem (2d Animation, grease pencil). In my case, drawing each frame made the last frame of the animation I planned (for example: 45 frames planned, one layer) repeat till the last frame of the playback (for example 100 according to the bottom bar where it says "start" and "end"). What I did was delete with the eraser tool the drawing in the frame that started the repetition (following the same example: frame 46) that I didnt want. Then, no more repetition in the timeline or through all the playback.
I dont know if it exist a more simple way to do it, TVPaint and Adobe Animate have more intuitive option to hold a frame to a certain position  of the playback


CP-symmetery conservation

Question: How can one show that for a given decay, say $\pi^+ \rightarrow \nu_\mu + \mu^+$, CP-symmetry is conserved or violated? Is there a visual way of doing such?
Answer: I'm not sure if it can be done just with this decay, as stated. I think you need the know the angular momentum and the spin of your particles to calculate the helicity
$$
h=\frac{\vec{s}\cdot\vec{l}}{|{\vec{s}\cdot\vec{l}|}}.
$$
if you find e.g. an anti-neutrino with the wrong helicity you'd know that CP is violated.
Comment: Well, the pion is considered to be in it's rest frame and has spin 0. This way the anti-muon and neutrino should have opposite and equal spin and momenta. This results in both the anti-muon and the neutrino being right-handed and thus a violation of parity (since not as many left- as right-handed particles are produced). Now how can one show that applying the Charge-Conjugation operator after the Parity operator (or vice versa) the CP-symmetry is conserved?

CP-symmetery conservation


Big vibration with Tektro Auriga brakes

Question: About a year ago I swapped the v-brakes with a Tektro Auriga kit. I immediately made a mistake by not properly bedding in rotors and pads, doing "powerful" brakes, sudden stopping of the bike and so on.. (but always on a flat road!).
So I immediately felt noticeable vibrations with moderate to strong braking.
I'm not talking about annoying noises but rather about vibrations that make the handlebar and the frame vibrate (at the rear), as you can see in this video (enable the audio). Cleaning the rotor many times, properly bedding in, and trying a semi metallic pad, did not solve the problem.
Only with a Shimano RT56 rotor I have no vibration, but less powerfull braking.
So the question is.. could i have ruined the rotor after a few braking?
Or maybe is just a sort of incompatibility between these rotors and my wheels (Mavic Crossride 26 both front and left)?
I don't know whether to buy a new Tektro tr-8 rotor or try something else.
PS: the Tektro rotor is not bent.
Comment: Are those the same wheels that you used with the V-brakes? I'm not sure if rim brake wheels can handle the lateral loads of disc braking properly.
Comment: No, got these Mavic Crossride Dual just a month before swapping from v-brakes to disc brakes.
Answer: What QR Skewer do you use?
I had the same problem on my QR disc brake bike. After upgrading to BB7 with a good, brand new rotor and good bedding in, the issue got better but did not go away completely. The scariest part was that the QR would just untighten with brake use, so I had to control regularly.
After that I upgraded the stock QR for a old Shimano internal cam one and the problem was completely gone. The issue was not only a weaker cam mechanism, but also that the stock QR had a plastic part that deformed under braking. The QR I now use is all metal.
Take a look at this article for more details: https://handsonbike.blogspot.com/2013/08/difference-between-good-and-bad-qr.html
Comment: I had never thought about the QR, believing I had been given the Mavic QRs.Instead I have just those "bad QR" that you see in the article you linked. [Pictures of the QR and fork](https://imgur.com/a/YQuSWzs). I tried the (15 years old) Shimano QR .. unfortunately it does not solve the problem. As you can see in the photos, however, it seems to me that the surface of the nut is quite smooth, even more so the surface of the fork on which they are pressed against.  Another source of problem?
Comment: I don't think so. The wearing seems normal to me.
The biggest cause of vibration that could be traced to the QR would be the plastic part.
Comment: Unfortunately, same vibrations with the old metal Shimano QR.
Answer: That kind of vibration can be difficult to eliminate without replacing the rotor.
The window pattern on a given rotor can contribute to it, as can the uneven transfer layer that can develop from not bedding in the rotor properly to start with.
Some improvement can be had by sanding aggressively, then cleaning and re-bedding the rotor. Sanding it off the hub is better because otherwise you'll bias the work on the easy side.
Usually I replace rotors outright to solve this problem because it's more of a guaranteed fix.
Comment: @Odradek There have been many times where I couldn't solve the problem with any solution that didn't involve the rotor winding up in the scrap bin.
Comment: Just sanded rotor and pads, at first it seemed better but after a few braking... vibrations again
Answer: Your question is not quite clear, but there is no braking power difference between rotor brands. Differences are solely in weight, design, durability, heat dissipation on long descents etc.
So if your RT56 rotor is not causing vibration, but it is less powerful, then it means that the other rotor is a different size. Otherwise the braking performance would be the same. Rotors of a different size will require an adapter also to fit to the same frame.
It is quite possible that a bigger rotor causes vibration where a smaller one does not, since the braking force is directly proportional to the diameter of the rotor.
I'd expect 160mm to be sufficient rotor size (you don't mention) for most purposes. Remember that most force comes from the front, so for XC MTB some people use 180mm front, 160mm rear. You could experience with using your RT56 rotors on the rear and the Tektro (?) on the front, or vice versa (depending on size).
Also your fork will definitely have a rated rotor size, which relates to the braking force the fork is designed for. If you are putting too much in, then it might well vibrate. You mention 26" wheels, which suggests an older bike - older forks were often 25.4mm, whereas today 32mm is standard. I'd review the rotor size specs for your fork and the rotor size originally fitted to the bike.
Comment: @Odradek I have experienced the type of problem you mention. The drilling pattern in the disc has some effect as well as the material. You will hopefully find the Shimano becomes more powerful as it beds in and pad material accumulates on it.
Comment: Both Tektro and Shimano rotors on the bike now are 160mm. The kit had 180 and 160 rotors. Thinking that the problem was the old fork, I emailed the manufacturer who confirmed that the fork is suitable for maximum 160mm rotors. So I bought a 160 mm shimano rt 56. But the problem remained with the Tektro 160mm rotor as well (this too not properly bedded in). However, i get those strong vibrations also wit the Tektro on the rear wheel.That's why I exclude that the problem is the fork, if it is not the rotor it can be only the wheels.
Comment: @JoeK Have you experienced the same amount of vibration as you can see in the video? After a year the Shimano didn't improve so much, it seems a little less powerfull.

Big vibration with Tektro Auriga brakes


How to calculate temporary/periodic similarities of an increasing series in real time?

Question: Considering there are two series over time and new data is added in the series over a gap of n second . The series might have periodic similarity/dis-similarity within themselves. How to calculate correlation among the series value in real time?
Comment: autocorrelation or cross-correlation? You need correlation of each series by itself or correlation between 2 series?
Comment: correlation between the 2 series
Comment: In my answer we assume you are not interested in total similarity
Answer: well, This is an interesting question! Let's formulate it again to be precise in answer:

I have two real-time streams of values. There are temporary similarities (transient similarities) between two. How to capture it?

As you are talking about similarity, I did not limit the scope to correlation. One may define another measure of similarity. I would say you should define your similarity function first (you may choose correlation. I do as well for my example) and a period of inspection (it's simply a window of length $m$ ending at current timestamp).
Using these two and starting from $m+1$th sample, you can calculate your similarity measure (here correlation) as a time-series. This time-series starts after $m$th sample of input series so keep it in mind to keep similarity measure and original timestamps synchronized. The interval between two consecutive points in output (similarity series) is defined based on the resolution you need. after $m+1$th sample you can shift your window on step at time and calculate the similarity accordingly. Then the intervals in output will be as same as input.
Of course it keeps you more away from real-time as the frequency and number of calculations is maximum. You can define a margine for yourself (let's say $d$ sample) and calculate similarity every $d$ time. Then you lose some info (discarding the samples in between) but you get closer to real-time (you will have $d*n$ seconds to perform computation).
Please let me know if it need clarification. Welcome to the community BTW :)
Comment: thanks alot..can this problem be solved without time-bounding ?
Comment: Welcome my friend. Tell me what you mean by tim-bounding and I will answer :)
Comment: can i send u a private message somewhere else..maybe ur email? where I can describe the problem  in a bit more elaborate way..if you are interested
Comment: You can simply google my name and fine me on Linkedin. BTW, if it answered your question you may consider accepting and if you liked it you may consider upvoting. This is the only appreciation as we use our private time for answering questions here :)
Comment: i have accepted your ans as the correct ans..however I lack enough points to upvote your ans..i would have gladly done so if I had enough points..thanx


Connecting two computers possible RDC

Question: OK. I have two computers one is a windows vista the other is a windows 7/8. how do I set up a connection between the two so the windows 7/8 can take control of the mouse and key board so the win 7/8 pc's keyboard and mouse will control the vista pc. They are both using a different wireless network. Any ideas.
Answer: To turn on Remote Desktop, press start and go to the Control Panel. Click on System and on the left will be link labelled Remote settings. Click that and a new windows will appear with the title System Properties. On the 'Remote' tab, there's a header 'Remote Desktop' with three radio buttons. If you are set-up on a domain, you can select 'Allow connections only from computers running Remote Desktop with Network Level Authentication', else click to 'Allow connections from computers running any version of Remote Desktop'. Follow this procedure for both computers.
On one computer, open up a command-prompt and type ipconfig to find your IP (should be something like 192.168.x.y).
On the other, press Win+R and type mstsc. Enter the IP address of the other computer and log in.
Comment: I am having problems with this as the windows vista pc as it is a home basic.
Comment: I don't think Vista Home has native remote support so you might need to use third-party software. [This article](http://www.ghacks.net/2007/02/12/add-remote-desktop-access-to-windows-vista-home-editions/) mentions TightVNC but I'll keep looking for other ways

Connecting two computers possible RDC


Book and article references sought for starting out with document classification

Question: I am interested in doing a project on document classification and have been looking for books that could be useful for the theoretical parts in text mining related to this or examples of articles describing the process of going from training data with documents classified (with subcategories) to a system which predicts the class of a document. There seem to be some (rather expensive!) titles available but these are conference proceedings with articles on smaller very specific topics. Can someone suggest books from the data mining literature that provides a good theoretical basis for a project on text mining, specifically document classification or articles with an overview of this process ?
Answer: Christopher D. Manning, Prabhakar Raghavan & Hinrich Schütze have a free information retrieval book. Try chapter 13 - Text classification & Naive Bayes.
See also the companion site for Manning and Schütze's nlp book, specifically links for the text categorization chapter.
Fabrizio Sebastiani wrote a useful tutorial about text categorization(PDF) and review paper of machine learning for text categorization (PDF).


What happens to async awaitable code in C# if the associated UI is disposed

Question: Say I have a WPF dialog in which I have async event handlers that await some call that takes a long time. Then the user closes the dialog (and the code disposes it) before that await has returned.  I would imagine that would cause a crash. Is there a prescribed way to handle this scenario using the new async/await keywords in C# 5 with the new TaskAsync methods in .NET 4.5?
Comment: Not a direct answer to your question, but have you considered preventing the user from closing the dialog box until the operation completes? I don't know how well this fits in with the user experience of your application, it's just a direction to consider.
Comment: Perhaps it is just the toy demos I've seen, but none seem to take this scenario into consideration. I'll look into cancellation.
Answer: async/await should work fine.
Each WPF window does create its own SynchronizationContext - at least right now (this is an implementation detail). But these are just simple wrappers around the common Dispatcher.
So, TaskAwaiter will end up capturing a SynchronizationContext for a window that gets destroyed, but it doesn't really matter because the Dispatcher is still there.
Now, what your code does is another story. e.g., if you have an async event handler in this situation, it has to be able to handle resuming on a disposed instance.
Both Adam and leppie have good comments: either prevent the user from closing the dialog, or cancel the task (and ensure it is cancelled before actually closing the dialog). Another good option - if your idea is to start an operation that should outlast the dialog - is to start the Task and then add it to a shared collection of in-progress operations. All of these options prevent the undesirable situation of an async event handler running on a disposed instance.
Answer: I think this depends on the exact situation. If you have code in an async method on a Dispose()d object, it can continue just fine, because Dispose() doesn't mean anything to the framework. Of course, if the method calls some method that will throw ObjectDisposedException (or some other exception), that will stop the async operation (unless you catch the exception). But it doesn't happen automatically.


is there a way to enforce a whitelist of programs (like AppLocker) on Windows Home Premium?

Question: I have my someones computer that I regularly fix up for him, usually because the people come and download illegal programs and porn.  I'm getting really tired of it and am looking for a way to whitelist a very small list of programs, firefox, word, etc, that can run, and nothing else.  I found the AppLocker for the corporate world, but is there anything similar for a family computer?
Answer: To stop people installing pretty much anything set them up a user level account rather than an admin level account. If they insist on letting others use their computer then can give this account out.
A more drastic way would be to set up a virtual machine which could be wiped and restored as necessary.
However, neither of these would stop the downloading of the files themselves.
Comment: AppLocker is a much tighter sandbox than just running LUA. It prevents untrusted code from executing at all. You can control the execution of binaries, DLL loading, scripts and installers. That means that malware targeting the user profile rather than going admin permissions will not execute. AppLocker is a really cool security feature and it's the main reason to prefer Enterprise and Ultimate SKUs. I'd like to see MSFT put AppLocker in all SKUs, enable it by default. They need to put a simpler management interface on it for the home user, though.
Comment: It will also not stop some portable applications like from PortableApps.com
Comment: @Halpo - you're right it won't. But setting up your users with standard accounts is still the _first_ step.
Answer: After trolling around in the settings I found the Parental Controls actually allow for both a white list and black list, but it seems that the settings are a little time consuming to set up.  But you can only set up the controls for a regular user.
http://windows.microsoft.com/en-us/windows7/Prevent-children-from-using-specific-programs


"example" heading in twitter bootstrap

Question: on the twitter bootstrap there are examples of the features and the examples are contained in DIVs with the class 'bs-docs-example'.
every such DIV has the string 'Example' written in the upper left corner. i want to know where is that string coming from and if i can use/customize it?
Answer: If you take a look at the Github for Bootstrap you'll see that .bs-docs-example has content: "Example" set for ::after (for explanation on how to manage content with CSS3 see here).
Basically, .bs-docs-example has this style attached to it:
.bs-docs-example::after
{
    content: "Example";
    position: absolute;
    top: -1px;
    left: -1px;
    padding: 3px 7px;
    font-size: 12px;
    font-weight: bold;
    background-color: whiteSmoke;
    border: 1px solid #DDD;
    color: #9DA0A4;
    -webkit-border-radius: 4px 0 4px 0;
    -moz-border-radius: 4px 0 4px 0;
    border-radius: 4px 0 4px 0;
}

If you modify content member you'll modify the text.
Comment: thx, it worked :)
apart from that i also had to change the position 'bs-docs-example' class to relative.
Answer: I know it's a little late, but I also wanted the same feature, but wanted to put custom text in place of the word example.  I came up with a quick little work around using existing bootstrap code that is very close, no hacking the bootstrap needed.
Maybe this can help someone else out that's looking

      YOUR CUSTOM TEXT

Basically you use the thumbnail class to get the border around your div, then use it again in a nested div and offset it and change the background color.  It looks extremely close except for the upper right and bottom left corners are slightly curved,  However you can put whatever you want in the box, text, links etc..

"example" heading in twitter bootstrap


Aligning texture

Question: How to make texture look same scale on side of the cylinder as on it's top?
Comment: The texture is  in object space, so it should look the same, with your mapping. Ctrl-A apply the scale of your object. It must have been scaled down in its 'up' direction in Object Mode, so the Object is carrying a non-uniform scale in its transform.  If you scale in Edit mode, you scale the mesh with respect to the object, rather than the object itself.
Comment: Further reading: https://blender.stackexchange.com/a/7349/3710
Comment: Ow, i forgot about it...
Thank you)
Answer: Many things can reduce the side texture distortion.
The easiest thing to try would be to apply scale. (Go to object mode, Object > apply > scale.)
If this doesn't work though, another thing to try would be to select all of the faces in edit mode, and scale it along an axis in the image editor, so that it "undistorts" the texture on the side.
As this would pretty much ruin the effects of the Smart UV project if you are using that to unwrap. It would be a last resort.

Aligning texture


PostgreSQL-dynamic sql inside function?

Question: I have a PostgreSQL function that takes one string as parameter/this is dynamic sql query/ and executes that dynamic SQL and I expect the result from the dynamic query.
It seems that in PostgreSQL I should predefine what I will return - but this is impossible since I am executing dynamic statement and sometimes I will return one int column, sometimes I will return 5 varchar columns....
Another thing is that existing jdbc code will call the function-and I cannot change it-I can't define the types dynamically like:
<code>{call execute_dynamic(?) as (a varchar(255),b int)};

The code that will call the procedure is:

{call execute_dynamic(?)}
</code>
and cannot be changed....
Is there a way to implement this?
Answer: The solution is to use refcursor as return type.
<code>OPEN ref_cursor FOR EXECUTE dynamic_sql;
 return ref_cursor;
</code>

PostgreSQL-dynamic sql inside function?


How to delete Gmail signatures

Question: I have defined multiple signatures in Gmail, but want to delete some of them.
How do I do it? I have figured out how to blank them out, but want to actually delete them so that they don't get selected by accident.
Comment: You can only have a single signature. Do you mean canned responses?
Comment: I understand exactly what the OP is asking. It is possible to have multiple signatures defined in Gmail, one for each "Send mail as:" email address. The only way to delete the signature is to delete the "send mail as:" email address that the signature is associated with.
Answer: Blanking the field out is the only way and gives the result you are looking for. You can only have one signature per email address; not sure what you mean by selecting one accidently.
Answer: I tried to remove an old signature in my Gmail settings and can confirm there is no simple way to delete a signature. I think your best bet is to just clear out the old signature or select the No Signature option.  Not ideal at all.
Answer: To remove the signature from Gmail you have to follow some steps.

First click on settings on the top right corner of your Gmail page.
Then click on the lab tab after clicking to the lab tab you find signature tweaks and enable that option by selecting the radio button.
Then click on the save changes buttons to save the changes made to the lab setting.

By the above process you can remove the signature from Gmail.
Answer: This seems to vary with different versions of Gmail. None of the answers I found were very helpful.
To delete a signature or change default do the following:

Click the cog on top right of mail screen and select Settings
Select the Accounts and Import tab
Alongside Send email as: you will find current signatures. You can delete, edit and change default here.

How to delete Gmail signatures


Does speaker calibration software reduce the life-span of the speakers?

Question: I'm wondering if using speaker calibration software could be exhausting the speakers by gaining up the frequencies outside of the speaker's natural frequency range, or if there is anything to be careful about.  Is calibration going to make much difference when producing music (I'm sure people have had success without it), and if it's so important then why don't we see calibration functions on consumer hi-fi or TV's?
Answer: You don't see it on consumer units because consumers don't need it enough to pay for it, nor could most of them tell the difference anyway judging by what most people's TV's & HiFi's sound like ;) Give a consumer a graphic EQ & they will just put a 'smile' on it without thinking any further.
This is what I had to strap permanently over a consumer 2.1 system recently to make it sound anything like flat. The bizarre shaping at the bottom is to overcome the ridiculously over-zealous sub, which actually only really pushes mid-low properly & leaves the actual lows out unless shoved hard.

...which I suppose brings us closer to an answer -
if you pull frequencies rather than push, then you're making the system do "less work" in its over-emphasised areas, rather than more. Having said that, unless you are going to run it at full tilt, it ought to be well within tolerance to run with that curve applied, forever. I have no worries for the low-budget consumer system I just EQ'd to death, it just never runs loud enough to become a worry, though that amount of extra 'shove' at the bottom end would heat the voice-coils if it was run at excessive levels.
This wasn't a true calibration, btw, just by ear - sufficient that I knew it sounded OK & its owner couldn't actually tell the difference until I A/B'd it for them, then they realised how the original managed to be fizzy, boxy & boomy... all at the same time ;)
A better system would usually need a lot less rough handling than that.


Behavior problems with two of my cats

Question: When my husband and I first moved in together we got our first cat,Lucky. About a year later we got another one and they got along great. Lucky took her under his wing and showed her the ropes. But recently it seems they almost never get along. Now I should start by saying we joke a lot that lucky is the alpha but in all reality he pretty much is. When we get a new cat he's the one that kinda gives them their "orientation". He has started chasing nipsey around and cornering her, it stresses her out so much that she actually poops herself. It's happened twice that I know of, if it's happened while I'm out of the house I don't know cause she's started running to the litter box to hide. I don't want this to cause any issues with her health or for her to be unhappy here but I don't know what else I can do other than get her away from him when I see it happening.
Comment: Welcome to Pets! Please take the [tour] to see how this site works, it only takes a minute. Do I understand correctly that you have a male and a female cat? Is any of them (or are both) neutered? Has there been any unusually stressful situation lately like movig to a new place, introducing a new pet or other member of the family? You can [edit] your question any time to add more details to it.
Comment: Yes they are one female one male, both have been spayed/neutered. We did move about 5 months ago but this isn't something really new to them as we are renters and have to move every year
Answer: Step One:  Observe your cats.
The first step in stopping bullying behavior is to observe your cats' behavior with a particular eye to the situations where bullying is happening, especially if there is a recurring pattern to it. Bullying generally takes the form of one of the following categories:

The cats are fighting over resources, like water, food, toys, or litterboxes, so the bully starts to guard these resources from the victim.
The bully traps the victim somewhere.
The bully ambushes the victim by finding some hiding spot the victim must walk past to get somewhere else, and then lying in wait for its victim.

Step Two: Change the environment so it no longer enables the bullying behavior.
Once you know where the problems are, you can do something about them.  All of above situations I listed are made possible by the cats' current environment. Therefore, if you change their environment so that these situations can no longer happen, the bullying behavior should be reduced.
In the case that resources are being guarded, simply get more of that resource. That way the bully can't possibly guard them all from the victim.
In the case of the bully trapping the victim, which is definitely happening in your case, you should rearrange your house so that the cats have places they can go to get away from each other that also have multiple escape routes, so the victim cannot be trapped. In the case of the litter box, I would remove the lid if there is one, so the cat can exit it from any direction, and move the litterbox away from corners and such, to make it so the cat cannot be trapped there.
But furthermore, the victim is clearly scared, so it's fleeing to a hiding spot and getting trapped. You should block access to other bad hiding spots where the victim runs and will just be trapped (like under furniture for instance), and then provide better alternatives by rearranging your existing furniture and buying new cat furniture to create secondary routes throughout the house that your cats can climb to to get away from each other. These routes should have multiple ways the cats can get to them, so that the bully cannot trap the victim there.
Lastly, in the case there are ambush spots in the house, similarly you should rearrange furniture to either block the ambush spots or to create alternate routes around the ambush spot, so the victim can no longer be ambushed there.
Step three:  Play with them together regularly in the same room at the same time.
You probably need two people, so that one person can play with each cat. And you want to make sure the bully is totally ignoring the victim for the toy, so make effort to grab its attention if you notice its attention wandering towards its victim.  Playing more with both of them has multiple benefits.
For the bully, it will take off some of the excess energy, so hopefully it will be less bored and have less energy for bullying. It is also a very good way to keep the bully distracted from the victim while being in the same room as its victim.
For the victim, playing in the same room as its bully can help build confidence because it will come to realize that it can be in the same room as its bully without being bullied.  A cat playing also gives off more confident body language. The more confident the victim is around its bully, the less it looks like a target for bullying.
Comment: Kai Thankyou for the input and directions. I will try and follow these steps and see if there is any change in their behavior. I will try and remember to post an update

Behavior problems with two of my cats


get node_exporter metrics for a single system user

Question: I have installed the node_exporter within the userspace of a linux system user. Everything works and I get the metrics in my grafana. But what I get is apperently the metrics for the whole host system (interesting, that I can get so much data about the host system as a simple user). But what I want is to see the CPU usage or RAM usage etc. just for my user, is that possible?
Comment: AFAIK, node_exporter itself doesn't provide such functionality, and it would be particularly misleading for memory due to buffers, shares and such. But if youare sure that you really need this, you can utilise textile collectors of node_exporter, and write a script that will be preparing needed data. Good starting point for this might be https://stackoverflow.com/a/28194733/21363224
Answer: What datasource are you using?
How do you transfer data from your collector (node_exporter) to grafana?
You could use a combination of telegraf agents and influxdb to create tags (eg users) and then filter your metrics based on those tags.


What makes the Forgotten Realms "forgotten"?

Question: If the Forgotten Realms are forgotten, who forgot them? Certainly not the inhabitants. Is there a lore explanation for why the Forgotten Realms are forgotten?
Comment: I used to know the answer to this question, but I no longer remember. ;-)
Comment: It sounds cool.
Answer: I wondered this before myself, I found that Wikipedia had most of my answers.

The Forgotten Realms is a fantasy world setting, described as a world
  of strange lands, dangerous creatures, and mighty deities, where magic
  and supernatural phenomena are quite real. The premise is that, long
  ago, the Earth and the world of the Forgotten Realms were more closely
  connected. As time passed, the inhabitants of planet Earth have mostly
  forgotten about the existence of that other world – hence the name
  Forgotten Realms.

The AD&D 2nd edition Player's Guide to the Forgotten Realms Campaign (TSR2142) explains on page 2 the name is based on its relation to our own world losing contact with and forgetting it:

What are the Forgotten Realms?
Some theorists explain dragons and other fantastic occurrences by postulating parallel worlds. In times past, they believe, travel between mundane worlds — like our own — and more exotic locales was easy and frequent. But we have lost contact, and lost the worlds themselves. Lost, or forgotten.
Abeir-Toril, more commonly Toril, is an Earth-sized planet dominated by a continent in its northern hemisphere. Called Faerûn in the west, it is here that the Forgotten Realms lie. […]
Comment: Do you have a more direct source you can cite for that? Wikipedia is not a reliable source, and that statement in the Wikipedia article has no citation itself. Essentially, someone could've just completely made that up and could be completely wrong.
Comment: I dug out my copy (ah, memories), and found the part to add to your answer. It's not quite as directly "it's called Forgotten because we (Earth humans) forgot it" as I remember either, but the implication is so tight that it overall conveys exactly that — hence us both remembering it saying so.
Comment: True, and I realized that too as I posted--I used to have a Forgotten Realms players handbook that said something of the sort, but that's just my word for it. Perhaps a better wiki link, with better sources, is Ed Greenwood's page: https://en.wikipedia.org/wiki/Ed_Greenwood#cite_note-Dragon_#244-1
Comment: @TigerDM Are you thinking of the softcover with the whitish cover? I have that somewhere and can check.
Comment: Amazing! Thank you for proving that my mind isn't as old as my body ;)
Answer: Forgotten Realms was originally the place that Earth's fantasy legends came from.
From a profile on Ed Greenwood in Dragon magazine #244 (p. 112):

The "Forgotten Realms" name originally came from the notion of a "multiverse" of parallel worlds.  Our Earth is one, the Realms another.  In Greenwood's original conception, Earth's fantastic legends derive from a fantasy world that we've now lost the way to—hence, the Forgotten Realms.  "Concerns over possible lawsuits (kids getting hurt while trying to 'find a gate') led TSR to de-emphasize this meaning," he says.
Answer: Ed Greenwood explained the name "Forgotten Realms" on page 4 of DM's Sourcebook of the Realms, as included in the 1e Forgotten Realms Campaign Set (1987):

Introductions
Ed Greenwood
Well met! Welcome to my world; the
Forgotten Realms. A vast land, full of
strange splendors—a living background
for vivid adventure. Elminster took me
there first.
Welcome to our world. Now the Realms
are yours, too; a world that has delighted
me for almost twenty years in all its rich
variety is presented herein—and in pages
yet to come—for you to enjoy and set
AD&D® game campaign play in. Only a
small area of the Realms can be squeezed
into these pages, so there's much to look
forward to if you come along for the ride.
It's been a long one for me thus far; the
Realms began in 1968 as a setting for fantasy short stories, and later (1975) was
developed and detailed, as the
DUNGEONS & DRAGONS® system
appeared. Regular play in the Realms
began in 1978, and still continues; the
present roster of regular players has
remained intact since early 1980. As the
ADVANCED DUNGEONS & DRAGONS®
system has appeared, book by book, the
Realms have been modified to conform
with official rules, and these (with the
unofficial additions published in
DRAGON® magazine from issue #30
onward, such as monsters, magical items,
spells and nonplayer character classes)
can be assumed to hold sway in the
Realms now. I have always treated the
Realms as a "real place" which I am viewing and reporting on rather than a deliberate creation, and I believe that has been
the key to making it live.
The "Forgotten Realms" derive their
name from the fictitious fact upon
which play in my campaign is based:
that a multiverse exists, of countless
parallel co-existing Prime Material
Planes (including the world presented
herein, our own modern "Earth," and
any other fantasy settings a DM may
wish to incorporate in play), all related
to the Known Planes of Existence presented in the AD&D system. Travel
betwixt these planes was once far more
common than is the case now (when
few know the means of reaching other
worlds, or even believe in the existence
of such fanciful places); hence, the
Realms have been "forgotten" by beings
of Earth. Our legends of dragons, vampires, and of other fearsome creatures
and magic are due to this formerly
widespread contact between the
worlds; most have of course become
confused and distorted with the passage of time and many retellings. That
corner of the Realms presented herein
is a strip of the heart of the western
part of only one continent of Toril, that
region known as Faerun (pronounced
FAY-er-OON; the name meant "home" in
a now-lost early human tongue). Much
more awaits the traveler, to be revealed
in later works.


Mathematically calculate heat capacity in varying pressure and volume conditions

Question: I understand that the heat capacity depends on depends upon both microscopic (molecular/atomic) and macroscopic (phase, temperature, pressure). If I have an environment wherein both - the pressure and volume are subject to change, how can I estimate the instantaneous heat capacity of a substance (liquid) in that case ?
Comment: Are you referring to the heat capacity at constant volume or the heat capacity at constant pressure?
Comment: @ChesterMiller I interpreted the question as a request for a formula which defines specific heat capacity in terms of quantities like pressure and volume conditions. The questions says "...wherein both - the pressure and the volume...".
Comment: @Chair Thanks.  You are certainly entitled to your own interpretation.  But I would like some clarification directly from the OP before expending any effort composing an answer.
Comment: @ChesterMiller.  I would like to know the behavior of both specific heat capacity at constant volume as well as  heat capacity in general.  I believe that these quantities for a liquid (say) doesn't have the same value  in conditions  where I have varying pressure ,volume., temperature. Please correct me if I am wrong.  I would like to calculate the new values of these quantities when  in such a dynamic environment. Hence, the request for a formula . Thanks !
Answer: The starting point for determining the volume dependence of $C_v$ is the equation:  $$dU=C_vdT+\left[T\left(\frac{\partial P}{\partial T}\right)_V-P\right]dV$$ This equation appears in every thermodynamics textbook, so I'm not going to derive it.  From this equation, it follows that $$\frac{\partial ^2 U}{\partial V\partial T}=\left(\frac{\partial C_v}{\partial V}\right)_T=\left[\frac{\partial\left[T\left(\frac{\partial P}{\partial T}\right)_V-P\right] }{\partial T}\right]_V=T\left(\frac{\partial^2P}{\partial T^2}\right)_V$$
A similar relationship can derived for the partial derivative of $C_p$ with respect to P at constant T starting with the equation:
$$dH=C_pdT+\left[V-T\left(\frac{\partial V}{\partial T}\right)_P\right]dP$$


Fisher convergence as sample goes to infinity.

Question: I was wondering how does the Fisher law behave when $n => \inf.$.
$F_{q, n-p} = \frac{SSE_0-SSE/q}{SSE/(n-p)}$ I expect the test statistics goes lower as n goes up but does the pdf of the law converges to something particular like a gaussian or something ?
Answer: I am not quite sure of your notation, but I hope this answers your question.
An $F$ distribution with degrees of freedom $m$ and $n$ is the ratio of two independent random variables.
The numerator is $Q_m$ with $mQ_m \sim \mathsf{Chisq}(m).$ That is, $Q_m$ is a chi-squared random variable divided by its degrees of freedom. Similarly,
the denominator is $Q_n$ with $nQ_n \sim \mathsf{Chisq}(n).$
As $n \rightarrow \infty,$ the denominator random variable $Q_n$ converges
in probability to $1.$ Thus, as $n \rightarrow \infty$ and $m$ is held fixed,
$F = Q_m/Q_n$ converges in distribution to $Q_m.$
The figure below shows the density function of $\mathsf{F}(5, 1000)$ in
black and the density function of $\mathsf{Chisq}(5)$ divided by $5$ as
a broken red curve.  Of course $n = 1000$ is not quite $\infty,$ but (I hope)
large enough to make the point.

The figure below shows a sequence of densities of chi-squared distributions,
divided by degrees of freedom, to illustrate increasing concentration about $1$
as DF increases.
Degrees of freedom are 10, 20, 50, 100, and 500, plotted in blue, green, orange,
red, and black, respectively.
Comment: So that means that as n goes to infinity the denominator basically becomes 1 but the numerator gets to be $X1/n1$     $with X1 = Chisq(n1)$ ? It looks like it's converging to a gaussian seeing the black curve. (altough not centered nor scaled)
Comment: Roughly speaking, Yes: A chi-sqared distribution is the sum of DF iid RV's (squared std normals), so by the CLT a sequence of standardized chi-squared random variables with increasing DFs converges to standard normal. Although dividing by DFs (as here) centers the chi-squareds at 1 (not 0) and makes the SDs converge to 0 (not stabilize at 1), you are seeing something like the 'CLT effect' in the _shapes_ of the distributions in the second figure.


Using references in MYSQL

Question: I got an answer to another question here:
DB Schema For Chats?
It's a great answer, but I am not understanding the bit about references. I can do SQL statements but I have never used references.

What are they used for?
How are they used?
Give an example please
Answer: The REFERENCES keyword is part of a foreign key constraint and it causes MySQL to require that the value(s) in the specified column(s) of the referencing table are also present in the specified column(s) of the referenced table.
This prevents foreign keys from referencing ids that do not exist or were deleted, and it can optionally prevent you from deleting rows whilst they are still referenced.
A specific example is if every employee must belong to a department then you can add a foreign key constraint from employee.departmentid referencing department.id.
Run the following code to create two test tables tablea and tableb where the column a_id in tableb references the primary key of tablea. tablea is populated with a few rows.
CREATE TABLE tablea (
    id INT PRIMARY KEY,
    foo VARCHAR(100) NOT NULL
) Engine = InnoDB;

INSERT INTO tablea (id, foo) VALUES
(1, 'foo1'),
(2, 'foo2'),
(3, 'foo3');

CREATE TABLE tableb (
    id INT PRIMARY KEY,
    a_id INT NOT NULL,
    bar VARCHAR(100) NOT NULL,
    FOREIGN KEY fk_b_a_id (a_id) REFERENCES tablea (id)
) Engine = InnoDB;

Now try these commands:
INSERT INTO tableb (id, a_id, bar) VALUES (1, 2, 'bar1');
-- succeeds because there is a row in tablea with id 2

INSERT INTO tableb (id, a_id, bar) VALUES (2, 4, 'bar2');
-- fails  because there is not a row in tablea with id 4

DELETE FROM tablea WHERE id = 1;
-- succeeds because there is no row in tableb which references this row

DELETE FROM tablea WHERE id = 2;
-- fails because there is a row in tableb which references this row

Important note: Both tables must be InnoDB tables or the constraint is ignored.
Comment: When you use REFERENCES, I think it also expects that the table must exist on the relationship's side.
Answer: The REFERENCES keyword shows a foreign key constraint, which means that:
FOREIGN KEY (`chat_id` ) REFERENCES `chats`.`chat` (`id` )

...the chat_id column in the current table can only contain values that already exist in the chat table, id column.
For example, if the CHAT.id column contains:
id
----
a
b
c

..you can not add any values other than a/b/c into the chat_id column.

Using references in MYSQL


Future proofing for 240V outlet

Question: I currently have a 12A EVSE that takes either 120V or 240V and uses a normal three-prong (NEMA 5-15) plug. I am looking to install a 240V outlet on a 50A circuit breaker to use with this EVSE, but I'm wondering which receptacle to use with this new outlet. I've ruled out a NEMA 5-15/5-20 receptacle, so I will need an adapter to use my current EVSE for any outlet I install. Would it make more sense to install a 14-50R receptacle, a 6-50 receptacle, or some other type?
Comment: What make and model is your EV, and what sort of chargers can you get for it?
Answer: EV charging is special. The EV can actually "dial the amps" to whatever the circuit can handle, but something must tell it what the amp limit is. That is what EVSE's do.
When I originally wrote this, I did not realize OP had a portable EVSE with a variety of adapter plugs.

Those adapter plugs are special; they have a 4th pin on the EVSE side which tells the EVSE the ampacity of the socket. (which the EVSE tells the car).  Using hinky adapters will cause the car to draw the wrong current, causing problems like nuisance trips or fire-based detection of Zinsco and Challenger breakers lol. When using these portable EVSEs, the ampacity of the circuit MUST actually match the socket type.
That said, it's perfectly fine to "fool" the EVSE with regards to voltage only, which is what this discusses with OP.  But really, the right thing to do is get the right connector end.  But let's say you have a 120V/30A TT30 socket, and they don't make one of those. It's OK to "cheater" the 10-30 or 14-30 plug to fit onto a TT30. That will tell the car "30A" (correct) and surprise, the voltage is only 120V - but the car knows what to do with that.
End edit/preface.  Other edits in the log.
NEMA 6-15 and you're done
Outlets aren't that expensive and neither are plain breakers.  Simply fit the correct one.  And the correct 15A or 20A breaker per NEC 210.21.

The third one.
If your wiring is 12 AWG or larger copper and your breaker is 20A, you can fit a NEMA 6-20 instead.
Now, noting this thing is dual voltage, the right way to deal with that is have it have a removable inlet (the way a PC does) that takes an IEC connector.  Then you simply change the cord to what you're plugging into.  However you can make a NEMA 5-15R to 6-15P cheater cord if you really want to. If someone finds a 6" long cord with a funny plug on it, that's a big fat hint to be careful what they plug in.
If you are thinking of wiring up a universal future adapter socket, you can't.  What you can do is run 6/3 cable (or #8 THHN in conduit) to a large 4-11/16" square junction box.    The large 4-11/16" square box gives you the room for big wires and splices.  At this point you can install any of these pairs:

NEMA 6-15 receptacle with a 15A or 20A breaker
NEMA 6-20 receptacle with a 20A breaker
NEMA 6-30 or 14-30 with a 30A breaker
NEMA 6-50 or 14-50 with a 50A breaker

Note that except for a 15A receptacle on a 20A breaker, the receptacle size must always match the breaker size.   And of course you can't exceed wire maximums.
Comment: Yes, for many reasons.  A 14-50 is not an option unless you install much larger wires and a 50A breaker. (Breakers MUST match receptacles amp ratings except a 15A receptacle is allowed on a 20A breaker only).  Even then, it would fail to protect the 15A device.
Comment: Thanks! Why would you recommend installing a 6-20 and adapting to 5-15/5-20, rather than installing a 14-50 and adapting to 5-15/5-20?
Comment: Ah, I mentioned the 14-50 and 6-50 receptacles in the question, but I updated the question to make it explicit that I will install on a 50A circuit.
Comment: @palswim OK, then you'd just need to change the breaker to match the receptacle.  The smallest receptacles and breakers may not be willing to talk to a #6 or #8 wire, so you'd have to pigtail that.
Answer: Eventually, I decided to wire the outlet as a NEMA 14-50 (hot-hot-neutral-ground) rather than a NEMA 6-50 (hot-hot-ground) because the I can re-wire to a 6-50 easily enough by capping the neutral wire and from my limited research, I found that more EVSE chargers used NEMA 14-50 rather than NEMA 6-50.
As far as adapting the outlet to my current charger, creating a NEMA 14-50 to a NEMA 5-20 homemade extension cord (cheater cable, as one helpful answer named it) did not pose too much difficulty.  Editor's note: This is a Code violation and creates significant danger, as the 50A breaker will not trip when needed to protect a 20A device.  UL listed adapters are made, which have internal 20A fuses to solve that problem, or a homemade one could be built with a fuse.
My EVSE (E346031) only draws 12A. A short would trip a 20A breaker or a 50A breaker, so I had no fear about overheating and the extension cord. For any other EVSE, I would probably have to create a different extension cord. Editor's note: No, it would not trip a 50A breaker. That's the problem! This also doesn't address time-to-trip in an inverse-time overload condition; a 50A breaker would trip far too late.
Comment: I find it odd that EVSE chargers use 14-50s since they have no use whatsoever for neutral....
Comment: Be aware that a 14-50 to 5-20 cheater cord is not to code, because (1) an appliance cord designed to plug into a 5-20 outlet need only be capable of sustaining 20 amps before melting or catching fire, and (2) your breaker will only pop over 50 amps, which leaves plenty of room for a cable-melting fire-starting fault to occur. It's not _common_ to see a fault draw 40 amps without being a dead short, but it is _possible_, and such a fault would almost surely burn down your house, so be careful and never leave a cheater cord unattended in use.
Comment: (Incidentally, you CAN adapt 14-50 to 5-20 in a way that IS to code, by getting an adapter that has an appropriate 20A fuse or breaker in it. Although I can't find one, and I can find LOTS of the not-to-code kind. Home Depot even seems to sell them, which confuses me.)
Comment: "A short would trip a 20A breaker or a 50A breaker" FALSE.  The trip curves are quite different, and there's a big "fail zone" in there where you are totally unprotected. Frankly, depending on the wire size and length, the wires resistance may be high enough to *preclude any possibility of* an instant-trip on a 50A breaker. So it would just sit there and burn until the thermal trip eventually popped, which might be "never" if it's drawing <67A.  This is bad advice and a Code violation.
Comment: Wait, are you saying you are putting 240V to a NEMA 5-15 socket?  They make UL-listed 14-50 to NEMA 5-15 adapters; UL approves them because they have internal fuses and present 120V to the socket *and not 240V*.

Future proofing for 240V outlet


Would not Wallace have understood that K would have valuable information?

Question: It is unclear to me why K was so badly treated by Luv -- she at one point mutters, "Do your fucking job..." while watching him remotely -- surely K could know and in fact does possess information about Ana that even Deckard does not have. So why not at try to win K over or at least torture it out of him?
Answer: Don't read too much into Luv's comment. In the moment you mention, she's swearing at K in precisely the same way an angry motorist swears at their car when it refuses to start: out of frustration and not a tiny bit of fear that the object of scorn is too broken to continue.
So, why doesn't Wallace try to get info out of K? Because Wallace has his hands on Deckard, who definitely knows more about the child than K.
The movie ends before we see how Wallace learns that Deckard has escaped (and Luv killed), so, for all we know, his next move would have been to try capture and interrogate K. (And I think the movie makes it clear that would be impossible.)
Comment: There's no indication that Wallace knows _anything_ about K to begin with. Luv is secretive and crafty.


Mosfet on or off

Question: When do we say that a nMOS or pMOS is "on" or "off"? Are there any voltages across terminals we should be looking for?
Answer: For MOS, the voltage from gate to source, Vgs, controls if it is on or off. PMOS turns on when gate is lower than source by the threshold voltage, Vgs(th).
Let's say Vgs(th) = -2V for a particular P-channel MOSFET. Then whenever the voltage from gate to source is -2V or below, then the MOSFET is on.
For NMOS, Vgs(th) will be positive. Let's say it is +2V. Then whenever Vgs is > 2V, the N-channel MOSFET will be on.
Vgs(th) will vary and will be listed in the datasheet. Generally, in order to really turn the MOSFET on strongly, you will want to exceed Vgs(th) by a good amount to make sure you are solidly in the "on" region.
I would be remiss if I didn't mention the body diode at this point. There is an intrinsic diode built into MOSFET's. Even when it is off, PMOS allows current to flow (with one diode drop) from drain to source. And NMOS allows current to flow (with one diode drop) from source to drain.
Answer: Just as logic has valid Logic in/out levels so do discrete FETs if you have a logical criteria.  For 74HC CMOS with Vt=1.5 and Vdd=5V that is a certain ratio to ensure low Ron and good noise margins. The ratio ensures adequate Ron 5/1.5 but with lower Vt FETs a ratio of 2 to 2.5 may be adequate, but more is slightly better.
Comment: I thought flow of drain current was a sure way of telling if a mosfet is "on" till i read about cmos inverters where if the input is low, the pmos device is "on" and the output of the cmos is high even though there is no current.. What is keeping the pmos "on"..? I am not sure what I am missing here
Comment: Drain current depends on the load Resistance when Vdd/Ids=RdsOn + load and "on" depends on your personal acceptance criteria compared to the rated RdsOn at some Vgs >> Vt. If there is no load then you expect no output current on Ids. Maximum current occurs at no load @ Vdd/2 when there is cross-conduction in CMOS e.g. >~ 50 Ohms for xxx ns which is why all CMOS IC's need a decoupling cap.

Mosfet on or off