What (if ever) is the context at which I should use the term "various and sundries?

Question: My neighbor uses the term/phrase "various and sundries" all the time, but first off, it seems like he just means the word "various" alone, but adds "and sundries" to it for some reason. And then once in a while I'll hear someone else say it. But what context is it supposed to properly be used in, if I should even try to use it at all?
Answer: Do note that the phrase is termed as 'Various and sundry'.
According to dictionary.com, various and sundry means:

of different kinds, miscellaneous, as in Various and sundry items did not sell, so they'll probably hold another auction. This expression is a redundancy, the two adjectives meaning just about the same thing.

Also, Pleonasm, in which I quote,

Fowler notes that many pleonastic set phrases were created (not originally created) to achieve emphasis, but because of overuse they now invariably wind up "boring rather than striking the hearer." Many of these—such as any and all; fit and proper; aid and abet; save and except; sole and exclusive; null and void; terms and conditions; cease and desist; and various and sundry—have been adopted from legal jargon. Other common pleonastic twins that usage authorities find objectionable include if and when; unless and until; compare and contrast (from educationese); first and foremost; and the much-despised each and every. The prudent copyeditor will completely eradicate such clichéd pairs.
Answer: "Various and sundry" (singular) is an English language cliche meaning, just as you correctly pointed out, "various." As a cliche, I recommend that you not try to incorporate it into your speech or writing; it is just a bad habit on the part of your neighbor. For more information, check out this: When is it appropriate to use the idiom "various and sundry" (With thanks to Brian Donovan.)


How to remove texture from old scanned photos?

Question: I have a picture here I need to remove the texture. I try the FFT method but I don't get the diamonds to black out when I do it, its sorta flat. whats the best way to get rid of this?
Comment: While some of the answers (like [this one](http://photo.stackexchange.com/a/33472)) to the other question might indeed be applicable here too, I don't believe this is really a duplicate. The type of texture in this image is different, and, in particular, the FFT method suggested in the accepted answer to the other question is likely to be useless here.
Answer: There are some sophsticated filters that are implemented in software such as the G'MIC plugin of GIMP. You can try this online here. I've never used G'MIC for texture removal and I have not installed it on my present computer, so I'm not sure if it has a good filter that works well  for this case.
Now, if some standard method doesn't work well, you can always try to examine the structure of the texture to see if some simple mathematical formula would be able to sort most of them out. If that works reasonably well then it may be that after you have processed the image yourself, a standard filter will work better (e.g. what is left may now have a sharp periodic structure and you can then easily remove that using FFT).
In this case, you can see that the structures are elongated in the horizontal direction while in the verical direction it is usually just two pixels wide. This means that you can write a simple program that checks for each pixel the difference between the brightness and that of  of the average of the pixels two steps above and below. If it is large then is likely due to the texture and you replace the pixel value by the average, otherwise you don't change it. Now, you want to stay away from edges, so you also want to check if the the pixel values 3 steps above and below are not too different from each other.
So, let's try to implement this using the free of charge ImageJ program. We split the picture in the 3 color components and apply the following macro to each component:
m1 = getPixel(x,y+2);m2 = getPixel(x,y-2); m3 = getPixel(x,y+3);m4 = getPixel(x,y-3);df = m3-m4; if(df<0) df =-df; av=(m1+m2)/2; w=v-av; if(w<0) w=-w; if(df<20) if(w>15) if(v>40)  v=av
So, if df is too large we're probably near an edge and we then don't want to proceed, if this is not the case then if w is large then that means that the pixel value differs a lot from the average of the pixels two steps above and below and if the pixel value itself is larger than 40 then that's very likely due to the texture being there,  we then want to replace the value by that average. The result is then as follows:

Now, this is of course a very crude way of removing the texture, so there is a lot of room for improvement.
Answer: Here is my attempt : I've used G'MIC filters "Remove hotspots" and "Smooth [Bilateral]" to achieve the cleaning.


What's the definition of incompleteness of a coordinate system and a spacetime?

Question: I always see in GR textbooks that some coordinates or some spacetime is incomplete, such as Rindler spacetime and spacetially flat FRW universe with only positive cosmological constant. This incompleteness may be not the incompleteness of geodesics, because, in the case of spacetially flat FRW universe with only positive cosmological constant that is half of the De-Sitter spacetime, every timelike and null geodesic is complete. Therefore what's the accurate definition of this incompleteness and which book has this definition?
Answer: Incompleteness of a coordinate system is not a canonical definition as that, for instance,  of geodesical (in)completeness. It simply means that the domain of the coordinate system does not cover the whole manifold (and perhaps there are several inequivalent extensions of the initial manifold represented by the given domain of the coordinate system). If a coordinate system is incomplete in this sense, there are geodesics in the domain of the coordinates which are not complete (the domain of their affine parameter is not the whole $\mathbb R$), but the converse may be false. In that case there is a true metrical singularity.


How to get info about visable markers on android maps v2

Question: Is there a way to get info about displayed markers on android google maps(v2).
i have markers with different colors (each color represent category to be displayed on map) and I wonder if it possible to hide specific group from the current viewable map.
Answer: I ran to this problem myself, couldn't find any reference in documentary for returning list of markers,
so I made a static class utility which holds the markers in an array.
Using Marker's getId() and remove() methods, documented here , I went to the specific marker according to Id and removed it from map.
Consider using separate arrays, holding each type of marker you have.
this will enable you to show the specific group you want by looping on the array and assigning markers like this:
<code> Marker marker = map.add(new MarkerOptions()
   .position(new LatLng(37.7750, 122.4183))
   .title("San Francisco")
   .snippet("Population: 776733"));
</code>
and the same thing for hiding marker (with remove method)
Comment: thanks for you replay. i also thought about this solution but in case i have a large set of markers i wanted to decrease my app memory footprint. if i wont find any solution i will use this one.
Comment: since we're in the same boat, I'll be glad to find more efficient way :D


Server RAM vs PC RAM

Question: We want to buy some server RAM (one piece, 8GB).  But since the price grows exponentially we are thinking about buying regular PC RAM instead.
Would this cause problems?  Should we go ahead and buy the PC RAM?
Comment: i don't think 'exponentially' means what you seem to think.
Comment: Why would you buy one piece of 8 GB RAM? Most any server has at least 4 RAM slots. If you needed maximum RAM you would buy 4 8GB pieces. If you needed 8GB you would buy 4 2GB pieces. But never 1 8GB piece...
Answer: The PC RAM is built for speed.
However, the Server RAM is optimized for crash resistance and loss of data.
The Server RAM usually contains ECC – Error Correcting Code. ECC also commonly called EDAC protected memory helps correct parity errors which makes ECC RAM less vulnerable to loss of data, data corruption and possibility of a crash. This makes Server RAM much safer. Due to the implementation of ECC, these RAMs are a bit slower than their PC counterparts and are pretty expensive too.
On the other hand, PC RAMs are manufactured for speed. These RAMs neither have ECC or are they compatible. Hence PC RAMs are faster than a Server RAM however, prone to crash or data loss when subjected to higher amounts of stress. ECC Memory would not be supported by PC Motherboards and the BIOS. Hence it is advisable to check if your motherboard and BIOS supports one if you are planning to make your desktop into a server.
Comment: I'd substitute 'cheap' for speed in your explanation, then you're golden.
Comment: Also, many servers require registered (sometimes called buffered) RAM, which is not at all compatible with standard RAM.
Answer: Any half-decent server will require ECC RAM, sometimes FB or Registered. Normal PC RAM won't fit.
Comment: Well technically speaking, it would fit... but it wouldn't boot.
Answer: Higher price should reflect better quality.
While the speed of the memory and whether it supports real error detection/correction should be specified in the part number, what you can't tell is the quality of the product - how much QA/testing there is, the quality of the components used. Typically you won't see a difference until a few months or more of usage.
There's no magic answer as to what to buy - even high quality components can fail on day one. Its just a balancing act between your budget, the architecture of your application (loding a single webserver out of a farm of 20 should have very small impact - but losing all your database capacity is different) and the actual hardware it is implemented on.
You should also think about how it affects any current warranty's for the hardware.
C.

Server RAM vs PC RAM


Bond enthalpy of hydroxide

Question: Why does it require more energy to break the first O-H bond in water than is required to break the second O-H bond?
Answer: The Masterton Hurley (6th ed.) textbook has a bond dissociation energy of +499 kJ/mol for breaking water into a hydrogen atom and the hydroxyl radical OH. The bond dissociation energy for breaking the hydroxyl radical into another hydrogen atom and an oxygen atom is given as +428 kJ/mol.
You could make the argument that you are starting out with a situation where all electrons are paired and end up with two radicals in the first step, whereas in the second step you already start with unpaired electrons (the hydroxyl radical has seven valence electrons).
In the title of your question, you mention the hydroxide ion. This is not a relevant species because bond energies usually refer to homolytic bond cleavage, with one electron each remaining with the two fragments. It would require heterolytic bond cleavage to go from water to the hydroxide ion (water reacting as a Bronsted acid). This reaction merely requires +55 kJ/mol in aqueous solution.
Some sources contribute to the confusion between hydroxide ion and hydroxyl radical in this context. For example, Boundless states:

For instance, the HO-H bond in a water molecule requires 493 kJ/mol to break and generate the hydroxide ion (OH–). Breaking the O-H bond in the hydroxide ion requires an additional 424 kJ/mol. Therefore, the bond energy of the covalent O-H bonds in water is reported to be the average of the two values, or 458.9 kJ/mol. These energy values (493 and 424 kJ/mol) required to break successive O-H bonds in the water molecule are called ' bond dissociation energies,' and they are different from the bond energy. The bond energy is the average of the bond dissociation energies in a molecule.

They incorrectly refer to the hydroxide ion (OH-) and should be referring to the hydroxyl radical (OH).

Bond enthalpy of hydroxide


Where can I get my horse?

Question: On one of the loading screens of Skyrim, I saw a horse and it said that they are useful for long distance transportation in the Skyrim world. However, looking through the current big city I was in I was unable to find any horses! Do I need to catch them in the wild? Did I miss something?
Comment: Where can I get my horse armor?
Comment: @DoozierBlake: You should ask a new question for that, click "ask question" in the upper right corner. :)
Answer: Look for the stables outside of the major cities. You can buy them there.
You can see where the stables are in relation to you (if there are any nearby) by keeping an eye out for the following horseshoe icon in your HUD compass:

They also show up with a similar icon on your map:

And finally, here's what the stables look like when you're in visual range:

You can also steal horses (found at stables or in the wild), but there's a 50 gold bounty placed on your head each time a guard is made aware of you mounting one. Stolen horses also run away when dismounted, while owned horses stay where you leave them.
Comment: Seems I can also find them in the wild or steal them according to Google, although I would rather have one soon than waiting for them to appear. A picture of such a stable would be nice; is the stable right outside the major city or rather somewhere between cities? I've only seen some watch towers and an abandoned town with some fights so far...
Comment: Added a screenshot and some clarification, thanks.
Comment: A good thing to note is that a stable icon appears on the bar at the top, I was playing and suddenly noticed that when running around the city rather than inside it. I don't think I have enough money to buy one yet so I hid inside the stable and stole the horse, I drove away and not a single $!@# was given... :)
Comment: As additional note the first horse that you will probable find, at Whirerun Stables, will cost 1000 gold.
Comment: FYI, you can supposedly find wild horses and take them as well as buying them.
Comment: Whassup with the courier?
Answer: You can take a horse from Whiterun Stormcloack Camp just north of High Hrothgar, right under the mountain. Leaves when you dismount, comes back when you fast travel.
Answer: There is also the opportunity to get a free white horse named Frost (if you succeed at a Persuasion attempt) at the completion of "Promises to Keep," a quest to retrieve ownership papers for said horse.  Look for Louis Letrush in the Bee and the Barb in Riften.
There's a second opportunity for a free horse on Katla's farm, south of Solitude. If you farm a bunch of leeks and potatoes and such for her to raise her disposition, she'll let you ride her horse(s) away, anytime you want.
Comment: Where do you get Frost's quest?
Comment: "Look for Louis Letrush in the Bee and the Barb in Riften."
Answer: If you complete the quest The Cure for Madness from the Dark Brotherhood (Spoiler) you'll receive Shadowmere as a reward.
Comment: Hi BeatMe, the question is asking how to do it in Skyrim, and it seems you thought it was Oblivion
Comment: Oh thanks. Skyrim does also have a quest with shadowmere as a reward, I did change the links. (But now the horses apparently are equal in hp and speed)

Where can I get my horse?


My model is magenta in Texturing Paint. What does it mean?

Question: I try to add texture to my cat.
My model is Magneta color in Texturing Paint. What doesn't it meaan?

When I select ViewPort Texture is like this.

I try to put hair in my cat. I don't know how .
Thanks
Answer: That magenta means that the material of your cat has a non assigned texture; the colored checkboard means that an UV map has been created referring to that image.
Open a UV Image editor window, select the colored checkboard, save it to your hard drive with a name like "Cat skin";
Select your material and load the saved "cat skin" as an image texture.
Now you should be able to paint it in texture paint mode.
It should work both in Cycles and Blender Internal.
To make your cat furry you will have to add to the skin material a new "hair" particle system and play with the adjustements.
Good luck!
Answer: In texture paint mode, you need to add a paint slot of your choice from the Tools menu. Probably, you would choose Diffuse from the drop down. Above that, you can choose between Image if you want to adjust a texture or Material to paint it by hand from scratch.


"Moving Property" function?

Question: I have a character who plays his walk animation when he walks, but what if he is behind a wall? He would look sort of goofy walking when hes in place. Is there a way I can have a property ("Moving") be toggled to 1 when hes changing his position (not rotation) in 3d space? Any helps is appreciated; I would like to have this in logic bricks if it is simple. Thanks!
Comment: Seriously? Stop using integers and use Booleans for true or false situations. You can simply have it detect True or False, instead of 1 or 0. toggle then works on Booleans.
Answer: You already answered your question by your own:
Behavior:
When moving play walk animation
This implies:
When not walking -> do not play walk animation.
As you do not explicitly told the character to stop (e.g. by command) you need to detect any events that stop it from moving.
There are many options to detect such events:

no movement requests from user
getting other requests from user (e.g. jump, run, stand, crouch)
hitting a wall
floating (e.g. when falling, jumping)
speed below a limit

I guess you want to know the last option. This is not possible with logic bricks. You need Python to activate actuators when the object does not move anymore:
<code>import bge
controller = bge.logic.getCurrentController()
owner = controller.owner

limit = owner.get("limit", 0.001)

lastPosition = owner.get("_lastPosition")
position = owner.worldPosition.copy()
owner["_lastPosition"] = position

if lastPosition is not None:
    travelledDistance = (lastPosition-position).length
    if travelledDistance <= limit:
        for actuator in controller.actuators:
            controller.activate(actuator)
</code>
This needs to be activated all the time (enable True Level Triggering).
Attention

this is inefficient and should be used at a very limited number of occurrences
this does not differentiate between other situations when the character is not moving (e.g. sitting, sleeping)
you can tweak the limit by setting a float property limit
Comment: A more efficient way is to use other detection methods, such as a collision sensor. Obviously this will only work on expected collisions (e.g. the character stops when the front part is colliding with a wall).
Comment: "this is inefficient and should be used at a very limited number of occurrences" - I will use this a lot and I need it to be able to reply quick many times; is there a way to fix that?

"Moving Property" function?


Can I use the chi-squared test of independence with skewed data?

Question: I have two variables, both categorical, one with skewed responses. How do you deal with skewed data in the chi-squared test? Are there any other relevant tests? I want to perform the test in SPSS.
Answer: For a categorical variable, skewness is not well defined (arguably: not even defined) unless the variable is ordered, as shuffling the categories would change the apparent shape of the distribution.
Even with an ordered categorical variable, any use of numerical values such as 1 to 5 is still no more than a convention, and skewness would vary with many acceptable recodings:  e.g. squaring to 1, 4, 9, 16, 25 preserves order but certainly not skewness.
I guess what you mean is that some cell frequencies are much higher than others. That is not in itself a problem except that you should watch out for very low expected frequencies in a chi-square test. Older literature was more timid on this point than more recent literature, but still watch out for expected frequencies $<1$.
There is no special action needed here except to watch out. In extreme cases, you might need to aggregate categories, or you might decide that a chi-square test was not helpful or appropriate.
What software you are using or prefer to use is incidental to this point.
Comment: Perhaps every one thinks that love is wonderful, or peace greatly preferable to war, or some such. That can happen.
Comment: Thanks Nick, the categorical variables are indeed ordered variables. The responses are way too positive (most important) on five point likert scale for some questions.


Why don't electrons create a hole when they leave donor atoms in n-type semi-conductors?

Question: I have learned that in intrinsic semi-conductor when electrons leave the atom they leave a hole (that can move) .
I also learned that when electrons leave the atom of a donor  in n-type semi-conductors it doesn't create a hole and I can't understand why .
From what I read , the reason for this is that these electrons don't exist in the valence band but exist in the donor level/band but I still don't understand why don't the electrons leave holes in the donor level/band.
When Electrons leave the donor bands , another electron can replace it ( if the electron that left was being able to get to this donor band then any other electron should be able to get to this donor band and replace the electron that left)
Answer: Holes are vacancies in the valence band that effectively behave as positively charged particles. On the other hand, donor states do not form a band: these state usually originate from the impurity atoms randomly dispersed through the crystal, at a density much lower than that of the host atoms. Of course, an electron leaving a donor site leaves behind a positively charged state, which contributes to scattering and thus must be incorporated in any realistic calculations of conducting properties. Such a state can also occasionally trap an electron, in which case it is referred to as a trap, and at extremely low temperatures all the n-electrons end up localized in the donor states (or similarly the holes become localized in the acceptors of a p-semiconductor).
To summarize: we do not call them holes, because in this context term hole has a more specific meaning than just an empty vacancy that can trap an electron.


How to restrict output of a neural net to a specific range?

Question: I'm using Keras for a regression task and want to restrict my output to a range (say between 1 and 10)
Is there a way to ensure this?
Comment: ... `min` and `max` are your friend? Is that want you wanted?
Comment: Yes, how would i use it though?
Comment: For Eg. model.add(Dense(1)) is my final layer. How do i add min, max constraints?
Answer: Write a custom activation function like this
# a simple custom activation
from keras import backend as BK
def mapping_to_target_range( x, target_min=1, target_max=10 ) :
    x02 = BK.tanh(x) + 1 # x in range(0,2)
    scale = ( target_max-target_min )/2.
    return  x02 * scale + target_min

# create a simple model
from keras.layers import Input, Dense
from keras.models import Model
x = Input(shape=(1000,))
y = Dense(4, activation=mapping_to_target_range )(x)
model = Model(inputs=x, outputs=y)

# testing
import numpy as np
a = np.random.randn(10,1000)
b = model.predict(a)
print b.min(), b.max()

And you are expected to see the min and max values of b are very close to 1 and 10, respectively.
Answer: Normalize your outputs so they are in the range 0, 1. Make sure your normalization function lets you transform them back later.
The sigmoid activation function always outputs between 0, 1. Just make sure your last layer has sigmoid activation to restrict your output into that range. Now you can take your outputs and transform them back into the range you wanted.
You could also look into writing your own activation function to transform your data.


Dwarf-like humans living in trees

Question: There is a scifi book that I read at least 10 years ago. I have no idea what the title or author is. The humans or humanoids that live on a planet are much smaller than we are. They live in huge plants or maybe trees. There's another race of creatures that live in the canopies of the trees/plants. It turns our that these other creatures are actually a metamorphosized version of the "humans". Something to do with the sun changing their skin to make it scaley, etc... I think there may also be a plot point of a dolphin being carried by an old man. That's all I know. Anyone have any ideas?
Comment: Brian Aldiss's [_Hothouse_](http://en.wikipedia.org/wiki/Hothouse_(novel))?  It has small humans in the trees and changed humans at the top of the trees.  The "carrying a dolphin" bit sounds familiar too though it's been a long time since I read the book.
Comment: Agreed that _Hothouse_ sounds plausible. Note that its US title was _The Long Afternoon of Earth_.
Comment: I have the same problem. In the book I am struggling to remember the folks on the planet communicate their feelings thru colors radiating from their chests. They live inside trees. And the damage done to their planet when the main character's ship landed must be repaired. This is very important.
Comment: possible duplicate of https://scifi.stackexchange.com/questions/40580/what-book-features-people-living-in-a-tree-who-move-up-it-in-a-bubble (which is not accepted but has a confirmation via OP comment)
Answer: This is Hothouse by Brian Aldiss, originally published abridged in the US as The Long Afternoon of Earth. Your description sounded familiar, but I read the book maybe 25 to 30 years ago, so the details were fuzzy. I found a copy at a local bookstore and all the points you remember are in the book.
In the book, Earth is tidally locked to the sun and the moon has drifted to one of the Earth-sun Trojan points.  The side facing the sun is covered with a jungle formed by a single banyan tree.  The story starts with a group of humans, led by a woman named Lily-yo, living in the middle layers of the jungle.  The elders of the group "Go Up", which is a funeral rite where they climb to the jungle's canopy, and hitch rides on board Traversers, giant plants that have spun webbing between Earth and the moon.  The story from there follows Gren, the eldest male remaining, as the whole group gets carried away from the jungle. Gren is banished from the group and has several adventures trying to get back to the jungle.  Along the way, he encounters the morel, an intelligent fungus, and the Sodal Ye, the dolphin you remember.

The size of the humans: when Gren first meets the morel, the morel tells him:

"I know much about humans.  Time has been terribly long on this world, and on the worlds in space.  Once in a very distant time, before the sun was hot, your two-legged kind ruled this world. You were large beings then, five times as tall as you are now.  You shrank to meet new conditions, to survive in whatever way you could." (From Chapter 10)

The metamorphosed humans are called flymen.  They are described as:

In some respects they resembled humans.  That is to say, they had one head, two long and powerful arms, stubby legs, and strong fingers on hands and feet.  But instead of smooth green skin, they were covered in a glittering horny substance, here black, here pink.  And large scaly wings resembling those of a vegbird grew from their wrists to their ankles.  Their faces were sharp and clever.  Their eyes glittered.  (From Chapter 3)

When Lily-yo and the other elders reach the moon, they have changed into flymen.  They meet more flymen, who tell them:

"All who make the journey from the heavy world become changed.  Some die.  Most live and grow wings.  Between the worlds are many strong rays, not seen or felt, which change our bodies." (From Chapter 5)

The dolphin is called the Sodal Ye and is carried overland by a human:

A giant fish shape, much like one of the dolphins she had seen during their voyage over the wastes of the ocean, had been carried by a stooped old man. (From Chapter 23)

Dwarf-like humans living in trees


DXA-Java on WebSphere

Question: Is the DXA-Java framework supported on WebSphere? We are using WebSphere 8.5 and the only documentation I've found references Apache Tomcat.
Answer: It should work, but we only tested ourselves on Tomcat, hence the Tomcat references in the documentation.
If you run into any issues (not related to Websphere setup or configuration) please set us know by logging them on Github https://github.com/sdl/dxa-web-application-java/issues
Comment: thanks so much for the quick response. Do you know if using WebSphere instead of Tomcat has any formal impact on the level of support on the framework?
Comment: Hi Jim, please note there currently isn't a formal support statement for DXA as mentioned in the documentation. Besides that, as mentioned, it should work and let us know if you run into issues so we can fix them if needed (we basically "support" the same application servers that SDL Tridion Content Delivery does). What I hear so far is that websphere is tricky to configure to use the right dependencies (those from DXA, and not its own defaults which are a different version). I hope somebody from the community that has it working can reply here with how they did it and what the gotchas are.
Answer: DXA Java works on WebSphere. You do have to take care of the class loading policy and you need to clean up some of the JARs though. Ginika recently wrote this helpful blog post about this topic: Setting Up DXA 1.7 Java Web Application on WebSphere 8.5

DXA-Java on WebSphere


What problems can come from AC not running for years?

Question: I have an 81 Chevy C10 that I inherited from my dad. This truck has mostly sat for the last seven years, with me running it enough to keep it in condition. I've been using this truck mainly for the last year now and have replaced parts as needed. I would really like to get the AC working again. It hasn't been ran in about 7 years now. The heat works fine. The AC had a leak before and needed to be charged to work but the leak was never fixed. What kind of problems can running the AC cause now? Can I just charge it up? Should I at least get it evacuated and charged with a dye first?
Comment: Years? You're supposed to run the AC at least once a month for a minute so that the fluids flow though it.
Answer: If it was never converted to use R134a instead of R12, you're not just going to be able to charge it up yourself, since something that old probably came from the factory with R12 refrigerant.  You need a license to buy R12 in the United States, and it's not cheap.  Since your system is compromised and needs attention anyway, you might as well do the R134a conversion if it hasn't already been done.  Here is a thread from a C10 forum.  Bare minimum for the conversion would be new service ports.  At the top end, a new accumulator (receiver/drier), orifice tube, o-rings, compressor and pressure cutoff switch.  There is probably a happy medium somewhere in the middle.
It's standard procedure to evacuate the system before charging.  You probably don't have much to recover, but sucking the system down to a vacuum can tell you how bad your leak is (by how long the system remains holds the vacuum).  Since your system has been open for so long, adding some oil when charging is probably a good idea.  Especially if you're going to do it yourself, since you'll be running the compressor while charging through the lower pressure port.
You'll need to charge the system to find the leaks.  A detector wand can pick up refrigerant as it escapes the system.  Adding UV dye when charging works, too.  You can find the leaks with a UV light.
Once you know where the leaks are you can evacuate the system again, fix them, and charge it again and see if you got them all.
You can probably do all the work yourself if you have access to the proper equipment to evacuate and charge (vacuum pump setup, gauges and hoses), but you really shouldn't be venting refrigerant to the atmosphere (especially not R12).  If you charge it and it leaks out, I guess that's one thing, but a shop would recover it and dispose of it properly.
As far as things to watch out for with a system that has been open for years, as Brian Knoblauch is pointing out, the compressor could be a problem.  Even if it's not seized, the seals could be shot from lack of lubrication.  If you haven't pulled the relay/fuses for it though, it's been getting power whenever you've had the defroster on.  It might not even be engaging due to low pressure, or maybe engaging and immediately shutting itself back off.  If you're hoping to salvage it, pull the relay and / or fuse for it until it's gotten some lubricant (or don't use your defroster).  I'd guess the accumulator / receiver / drier is shot. As for the rest of the system, if moisture has gotten into it, you could have leaks everywhere due to corrosion.  I wouldn't be surprised if you had to replace the accumulator (receiver / dryer), orifice tube and possibly the compressor along with dealing with whatever hard lines or hoses are leaking.  You might get off easy, but then again, you might not.  Labor is not going to be cheap.  You're probably going to be using aftermarket parts, since the originals were meant for R12 and they're long discontinued anyway.  The good news is an assessment should not break the bank, it should be around a hundred bucks to vacuum and charge the system, maybe a little extra labor to check for the leaks.  Then you just have to decide if the bill for fixing it is something you can bear.
Comment: I'm pretty sure it was converted to R134a. I think AC Repair is a little beyond my comfort zone so I'm going to take it to a shop but I prefer to know what I'm talking about and make sure the shop isn't adding on things that aren't needed. Do you know of any problems that not running the AC in so long might cause for the rest of the engine though?
Comment: If the compressor seizes while the engine is running, it's going to be bad news for the belt that drives it.  In that case other accessories, if any, on the same belt will no longer be driven.  Probably won't stall the car and/or hurt the engine, but I suppose it's not impossible.
Answer: There's a possibility that the compressor will have seized up from sitting so long.  They really need to be run periodically.  However, I've seen some that have sat a long time fire up again just fine.
Comment: The other thing I've heard is that they are oiled by the refrigerant - so if you run them with low or no refrigerant that might cause them to break, too.


What animal is this digging holes in my yard?

Question: What animal is this digging holes on my property and should be be concerned about the walkway and the nearby garden walls?
Comment: How wide are the holes and where in the world are you?
Comment: @Jurp  1/2", Philadelphia, PA
Answer: Appears to be anthills, usually not a particularly huge issue, unless they are nasty bitey ants, or ants that would be unlikely to have holes like that (such as carpenter ants, which nest in wood and can damage wooden buildings.)
Local to me we have invasive European fire ants that I kill with abandon, and other ants I don't. Unfortunately that does mean the only workable way to kill the fire ants is by crushing - poisions kill them all, and the invasives come back stronger. Boiling water on the nest is another possibility if you know where the nest is. Selectively killing the invasives while leaving the others alone helps move things towards a more normal balance, but is tedious.
If you are not getting bitten, most likely fine to leave those alone.
Comment: There is also a beneficial parasitic wasp that leaves these kind of holes in lose, sandy soils. This is why I asked about hole size and location. Their holes are solitary and grouped in the same location, just like these. If I get a response to my question and the diameter and location match, I'll post it as an answer.
Answer: Based on your comment that the holes are half an inch in diameter, I think the holes were made by a ground-digging wasp rather than ants (unless you can actually see ants using the holes as entrances/exits to their nest, of course).
Here in Wisconsin, holes like you've described/pictured are often made by the Great Golden Digger wasp (Sphex ichneumoneus), which uses each hole to house a paralyzed prey insect and one egg. The dig only in loose soils or compacted sand, but not loose sand. This matches the paved area where the holes in your yard are located. The wasps are large but ignore humans, although I suppose if you got in the way of a wasp while she was digging her hole she might sting. They're in many places in my yard and have always left me alone.
Another possibility is a wasp with apparently no common name, called Ammophila urnaria. It is common in the Eastern US, but appears to cover the entrances to the holes after it finishes laying its egg.
There are other digging wasps, such as Cicada Killers, but none really match what you've pictured.
Comment: @Brōtsyorfuzthrāx. You're right, there are many other diggers. I found a site with 17 different species listed, including the two in my answer. The Tarantula-killer wasps are probably the biggest, but those live in southern states; they also have the most painful insect stings in the world. Many (like the Great Golden Digger) are not wasp-waisted.
Comment: We get burrowing wasps every year, these years. They're really cool. They're large and long, without skinny parts, and don't look like any of the ones you've mentioned by name. They fly around their holes a lot (quickly), and play with each other. Their abdomens throb. I usually see them in the early morning after the sun has come up. I've only been stung by one when it was disturbed by us piling firewood over/around its hole (it stung me in the middle of the top of my foot). They like dry bare soil, but sometimes make homes in cracks in driveways and stuff like that.


Python Infinity - Any caveats?

Question: So Python has positive and negative infinity:
float("inf"), float("-inf")

This just seems like the type of feature that has to have some caveat. Is there anything I should be aware of?
Comment: Note that the constant `1e309` will be interpreted as `+inf` and `-1e309` will be interpreted as `-inf`.
Answer: Python's implementation follows the IEEE-754 standard pretty well, which you can use as a guidance, but it relies on the underlying system it was compiled on, so platform differences may occur. Recently¹, a fix has been applied that allows "infinity" as well as "inf", but that's of minor importance here.
The following sections equally well apply to any language that implements IEEE floating point arithmetic correctly, it is not specific to just Python.
Comparison for inequality
When dealing with infinity and greater-than > or less-than < operators, the following counts:

any number including +inf is higher than -inf
any number including -inf is lower than +inf
+inf is neither higher nor lower than +inf
-inf is neither higher nor lower than -inf
any comparison involving NaN is false (inf is neither higher, nor lower than NaN)

Comparison for equality
When compared for equality, +inf and +inf are equal, as are -inf and -inf. This is a much debated issue and may sound controversial to you, but it's in the IEEE standard and Python behaves just like that.
Of course, +inf is unequal to -inf and everything, including NaN itself, is unequal to NaN.
Calculations with infinity
Most calculations with infinity will yield infinity, unless both operands are infinity, when the operation division or modulo, or with multiplication with zero, there are some special rules to keep in mind:

when multiplied by zero, for which the result is undefined, it yields NaN

when dividing any number (except infinity itself) by infinity, which yields 0.0 or -0.0².

when dividing (including modulo) positive or negative infinity by positive or negative infinity, the result is undefined, so NaN.

when subtracting, the results may be surprising, but follow common math sense:

when doing inf - inf, the result is undefined: NaN;

when doing inf - -inf, the result is inf;

when doing -inf - inf, the result is -inf;

when doing -inf - -inf, the result is undefined: NaN.

when adding, it can be similarly surprising too:

when doing inf + inf, the result is inf;

when doing inf + -inf, the result is undefined: NaN;

when doing -inf + inf, the result is undefined: NaN;

when doing -inf + -inf, the result is -inf.

using math.pow, pow or ** is tricky, as it doesn't behave as it should. It throws an overflow exception when the result with two real numbers is too high to fit a double precision float (it should return infinity), but when the input is inf or -inf, it behaves correctly and returns either inf or 0.0. When the second argument is NaN, it returns NaN, unless the first argument is 1.0. There are more issues, not all covered in the docs.

math.exp suffers the same issues as math.pow. A solution to fix this for overflow is to use code similar to this:
  try:
      res = math.exp(420000)
  except OverflowError:
      res = float('inf')

Notes
Note 1: as an additional caveat, that as defined by the IEEE standard, if your calculation result under-or overflows, the result will not be an under- or overflow error, but positive or negative infinity: 1e308 * 10.0 yields inf.
Note 2: because any calculation with NaN returns NaN and any comparison to NaN, including NaN itself is false, you should use the math.isnan function to determine if a number is indeed NaN.
Note 3: though Python supports writing float('-NaN'), the sign is ignored, because there exists no sign on NaN internally. If you divide -inf / +inf, the result is NaN, not -NaN (there is no such thing).
Note 4: be careful to rely on any of the above, as Python relies on the C or Java library it was compiled for and not all underlying systems implement all this behavior correctly. If you want to be sure, test for infinity prior to doing your calculations.

¹) Recently means since version 3.2.
²) Floating points support positive and negative zero, so: x / float('inf') keeps its sign and -1 / float('inf') yields -0.0, 1 / float(-inf) yields -0.0, 1 / float('inf') yields 0.0 and -1/ float(-inf) yields 0.0. In addition, 0.0 == -0.0 is true, you have to manually check the sign if you don't want it to be true.
Comment: Well, nearly: 1 / float('infinity') == 0.0
Comment: A small nitpick: not every calculation with infinity yields infinity: `-1 * float('infinity') == -inf`
Comment: That's why I said it was a _small_ nitpick. You had me worried for a minute that sign would be totally ignored when working with infinity, and I wanted to clarify for other people.
Comment: @Phil: Although I am pretty sure you were just trying to show that not all calculations with inf result in inf or NaN, I just wanted to make it clear to others that may be reading through the comments, that 1/float('infinity')==0.0 is true; for, as you are approaching infinity, the result of the division approaches 0.  I know it's just basic calculus, but I wanted to be sure those reading understand, or at least have a clue as to why, the result is what it is.
Comment: I have the feeling that this answer is much better than the accepted answer.
Comment: @Eval: I'm not sure what you mean, as the example calculation you give yields infinity and in my post I wrote about the only exception I know of: multiplication with zero.
Comment: I'd say `-inf != inf`, much like `-1 != 1`.
Comment: @Evan: yes of course, `-inf != inf`. But my point was, either are infinity and every calculation with them yields infinity (or `NaN`). Maybe I should've made that more clear in my post.
Comment: @Chris, thank you, but only the op has the power to change the accepted answer, provided he agrees ;)
Comment: Although `-0.0 == 0.0`, `-0.0 is not 0.0`, and all integers in Python which have the same value are the same object. (Don't know if this is per spec., but it is true in CPython/PyPy)
Answer: You can still get not-a-number (NaN) values from simple arithmetic involving inf:
>>> 0 * float("inf")
nan

Note that you will normally not get an inf value through usual arithmetic calculations:
>>> 2.0**2
4.0
>>> _**2
16.0
>>> _**2
256.0
>>> _**2
65536.0
>>> _**2
4294967296.0
>>> _**2
1.8446744073709552e+19
>>> _**2
3.4028236692093846e+38
>>> _**2
1.157920892373162e+77
>>> _**2
1.3407807929942597e+154
>>> _**2
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
OverflowError: (34, 'Numerical result out of range')

The inf value is considered a very special value with unusual semantics, so it's better to know about an OverflowError straight away through an exception, rather than having an inf value silently injected into your calculations.
Comment: A simple float addition, multiplication, etc will happily produce inf though: f=1.3407807929942597e+154; f*f => inf. It seems rather an exception of ** to raise an OverflowError.
Comment: @Lutz if it comes up as multiplication then, it's still inconsistent behavior.  Certainly big*big is not infinity, either.
Comment: @Abel That is not buggy. Overflowing means the number is very large. Too large to represent it, but still _far_ smaller than infinity. Putting infinity into such a place may be useful for the exception handler of your particular application logic, but would be incorrect for Python in general.
Comment: @eregon, actually, `**` seems a tad buggy. When it overflows with real numbers, it throws an error, but when any of its operands is `inf` or `-inf`, it returns either `0.0` or `inf`. So it _does_ work correctly when the input is inifinty, but not when the result should be infinity.
Answer: So does C99.
The IEEE 754 floating point representation used by all modern processors has several special bit patterns reserved for positive infinity (sign=0, exp=~0, frac=0), negative infinity (sign=1, exp=~0, frac=0), and many NaN (Not a Number: exp=~0, frac≠0).
All you need to worry about: some arithmetic may cause floating point exceptions/traps, but those aren't limited to only these "interesting" constants.
Comment: So if my arithmetic too large it might become an inf?
Comment: @Casebash No, it will cause an `OverflowError`.
Answer: I found a caveat that no one so far has mentioned. I don't know if it will come up often in practical situations, but here it is for the sake of completeness.
Usually, calculating a number modulo infinity returns itself as a float, but a fraction modulo infinity returns nan (not a number). Here is an example:
>>> from fractions import Fraction
>>> from math import inf
>>> 3 % inf
3.0
>>> 3.5 % inf
3.5
>>> Fraction('1/3') % inf
nan

I filed an issue on the Python bug tracker. It can be seen at https://bugs.python.org/issue32968.
Update: this will be fixed in Python 3.8.
Answer:
A VERY BAD CAVEAT :   Division by Zero

in a 1/x fraction, up to x = 1e-323 it is inf but when x = 1e-324 or little it throws ZeroDivisionError
>>> 1/1e-323
inf

>>> 1/1e-324
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: float division by zero

so be cautious!

Python Infinity - Any caveats?


New airplane certification required for airplanes operated by non-American airlines?

Question: I read the news today that Chinese made C919 is certified by its government.   Does FAA need to certify this aircraft before it can land in the US even thought operated by a Chinese airline ( or any other non-American airlines)?
Comment: C919 isn't a plane that's supposed to fly a trans-pacific route.....
Comment: @user3528438 That was my first reaction to the question. Why would a Chinese aircraft manufacturer seek FAA certification for an aircraft that is meant to operate almost entirely in the domestic and/or Asia markets, will likely not find buyers in the US, and doesn't have the range to fly to any US airports in the first place unless it's a non-pax ferry flight with special interior tanks?
Answer: The Federal Aviation Administration (FAA) and the Civil Aviation Administration of China (CAAC) signed an implementing agreement in October of 2017 under the U.S. – China Bilateral Aviation Safety Agreement (BASA) recognizing each other's regulatory systems with respect to the airworthiness of aviation products and articles.
FAA Press Release
Answer: The Chicago Convention states that aircraft certification is up to the state of registration, regardless of which state it's operating in.
So, if the Chinese govt certifies an aircraft registered in China as airworthy, then it can legally operate in any member state.  In theory, the FAA wouldn't even be involved until someone wanted to register that aircraft in the US.
However, in practice the leading aviation regulators (FAA, EASA, etc.) work together and have harmonized their requirements, so if an aircraft is certified in one of them, it can easily be certified in all the others. This also has the (probably intentional) side effect of nearly all aircraft design and production taking place in these countries, so China's CAAC joining that club in 2017 was a big deal for them.
Comment: From what I read, Boeing 737 MAX needed to be recertified in both the US and China.
Comment: @ManyMore In the US for US-registered planes, in China for China-registered planes. Plus the MAX incident was not a normal case.


Are articles without any abstract reliable?

Question: I'm writing a thesis which consists in a literature review and I came across some articles whose titles seem to be appropriate for my research, but they don't have any abstract and their full text is unavailable. Before even trying to get those full texts, which might require some time and effort, my question is: are they reliable? I mean, what are the possibilities of finding a peer reviewed article which doesn't have an abstract?
Comment: Does the citation indicate they are not journal articles, for example, book chapters? These may not follow the same format. Another possibility is that they are titles for posters or conference presentations.
Comment: Do you mean that a cursory observation of a web hit doesn't include the abstract, or that the citation tool entry doesn't include the abstract, or that you've gone and LOOKED at the actual paper an find that it doesn't have a abstract.  These are very different things, and only the last case really means there is no abstract.  You have no truly reliable way of knowing without going to the full text.
Comment: What do you mean by "have no abstract" as the only way I can think to check this is too look at the first pages of the paper.  If you are looking on some database, please tell us which one.
Comment: Also it depends on the field **and** the year. Maybe math papers in the 20s had no abstract.
Comment: Welcome to Academia SE! Please provide the titles of two or three of these articles and their links and this would help you get high-quality answers. It is hard to answer "is such an article reliable" without having any idea of which articles you are talking about. Perhaps for confidentiality you do not want to list the article names, but if you could, then that would help others help you.
Answer: It is impossible to say without actually examining them, but you can get a fair idea by knowing the journal in which they appear. If it is reputable, then the chances are that the paper is.
Also, there is a difference between not having an abstract and not having a published abstract.
You probably need to get the articles to be sure, however, but that is true of everything. See an academic librarian to ease your task. They can probably also give you advice on the reputation and reliability of publishers.
Answer: As to the literal question on papers without abstract, I would say that not having an abstract is becoming less common, but it not really a sign of quality. Shorter papers really don't need an abstract (or a discussion section) if they have a good introduction.  This is the "say something once, why say it again" philosophy.
Many journals will not allow a paper without an abstract.  The journal that published a paper of mine with no abstract now says "the article should include an abstract of at most 150 words" so it seems you might be able to publish a paper there without an abstract if you insist.
Of course, you still need to look to the paper to see if it has an abstract.  No database covers all papers and has zero omissions.
Answer: It's definitely possible. For example most news articles don't come with abstracts. Same goes for most popular-level articles, editorials, monographs, etc.
The publication venue says more about the reliability of the article than the presence of an abstract.
Answer: It is quite possible that the answer is whatever database you are using does not have the abstract, rather than the original paper not having one.
This is quite common for older papers - many of the literature databases are stitched together out of all sorts of older databases, some of which had citation details only, and going back to add them in is a laborious task which may not be very highly prioritised.
Take Nature, for example. Web of Science has it covered since 1900, but abstracts are only included from ~1990. In Scopus, it is covered right back to 1869, but the abstracts only go to ~1950 (and seem to miss 1965-66 for some even odder reason).
And of course papers that are harder to find online may be more likely to be older, obscure, etc and less likely to be comprehensively indexed on databases. So it's unlikely to automatically indicate it's of low value or not worth investigating.


Why the whole wire moves when lorentz force acts?

Question: We know that magnitute of lorentz force is directly proportional to the current in the current carrying wire.
But since the force is acting on the charges,shouldn't they get exited or thrown out when the magnitude of the force crosses the binding force between them and opposite charges?Please tell me if such phenomenon occurs.
Also when electrons move in a wire we usually say positve charges are moving in opposite directions,though not actually,I am talking about holes moving.So should the lorentz force also act on the positive charges?
Comment: Can one produce field emission using a transformer? Yes, that's usually how it's done. Normally we do try to avoid field emission, though, since it's rarely useful and it's actually quite limiting in building accelerator cavities.
Answer: Each charge carrier in the wire generates its own magnetic field and, as you pointed out, the overall magnetic field generated by the wire is somehow proportional to the current flow within the wire. And yes, the charge carriers do feel their own magnetic field, but usually this is a negligible effect and almost never enough for the particles to "break" the wire and exit out.

,shouldn't they get exited or thrown out when the magnitude of the force crosses the binding force between them and opposite charges?

If the magnitude of the applied force due to their own magnetic field were so strong to break the normal reaction of the wire upon the particles themselves then yes, this might happen. But for standard particles and standard wires this is just never the case. Wires are usually built taking into account all the possible counter-terms generated by the self-interactions. Notice that in general everything that is allowed by nature to occur does in fact occur, but the overall contributions and effects that you see are only the ones of the prominent forces.
Furthermore

Also when electrons move in a wire we usually say positve charges are moving in opposite directions,though not actually,I am talking about holes moving.So should the lorentz force also act on the positive charges?

the Lorentz force acts on every charge, whether positive or negative. Then particles move according to the Newton's law, taking into account all possible minus signs. Holes are not actual particles: what happens is that the electrons move away and leave their original positions, which can be replaced by other electrons and so on and so forth. The overall effect is as if there were positive charges moving towards the opposite direction, but that is just a pictorial representation to take into account the displacement of the single electrons from the original position.
Comment: I read the very basic concept of special theory of relativity applied in electromagnetism which tells me that when charged particles are at rest it will experience lorentz force since it is moving in opposite direction to the other external moving charged particles.Can this be applied to the positive charges as I mentioned above.Though positive charges are not themselves moving but when an electron move a temporary positive charge is created  at that place which in the process of moving of electrons are considered as if positive charges are moving
Comment: Can the case above as I mentioned in comment applicable for externally applied magnetic field.
Comment: Am I correct to say that for two current carrying wires the lorentz force acts as if individual charged particles of one wire are contributing its force on individual charged particles of other wire thus again there is negligible effect for particles to break through.Or by negligible effect you mean net effect is negligible.
Comment: You are making confusion among too many things at a time. Choose the particle you want to describe and your reference frame; then, whether classical or relativistic, write down the equations and find the solutions. About the hole theory, no, no positive particle is "created" in the wire, it is just a pictorial representation. And yes, you can apply all this to magnetic fields and all the rest, just changing the right hand side of the equation of motion (but that's too many things at a time, open a different question in case).


iTunes not showing music ripped from CD

Question: I have hundreds of ripped music CD files on an external drive and iTunes currently points to that library and file location. I've had this library since Yosemite and now run High Sierra. The issue is iTunes version 12.8.x doesn't seem to access these files directly and all of the playlists are missing (I have iTunes Library.itl library files dating back years I can swap out but none seem to work). All the ripped songs appear in the iTunes Music Library browser as before, but they all have a cloud download icon next to them in iTunes. How do I get iTunes just to show and play the ripped files from the hard drive without having to download them from icloud or stream them. I'm currently off-grid so don't have to broadband with lots of bandwidth.
Answer: After endless futile searches I found that the iTunes library for 12.8.x uses an xml file to reference the original music files. For some reason this file referenced the ~ user library and not the external drive where the music files are located. I did a search and replace in BBEdit and it relinked to the local files on relaunch.

iTunes not showing music ripped from CD


What was John Wycliffe's view of baptismal regeneration?

Question: Did John Wycliffe affirm baptismal regeneration as a general rule of faith? Or did he hold a more symbolic view of baptism?
Answer: It is reported that John Wycliffe stated :

... baptism doth not confer, but only signify grace, which was given before

This is reported in the following citation :

There is some evidence that Wycliffe rejected infant baptism, at least toward the end of his life. There is evidence of this from his own writings. Wycliffe taught that "baptism doth not confer, but only signify grace, which was given before." This principle undermines the doctrine of infant baptism. The Martyrs Mirror, first published in Dutch in 1660, states that in 1370 Wycliffe issued an article "declared to militate against infant baptism" (p. 322).
There is also evidence of this from the Catholic authorities. Thomas Walden and Joseph Vicecomes claimed that Wycliffe rejected infant baptism and they charged him with Anabaptist views. Walden, who wrote against the Wycliffites or Hussites in the early part of the 1400s, called Wycliffe "one of the seven heads that came out of the bottomless pit, for denying infant baptism, that heresie of the Lollards, of whom he was so great a ringleader" (Danver's Treatise, p. 2, 287, cited by Joseph Ivimey, History of the English Baptists, 1811, I, p. 72).
Even if Wycliffe did not entirely deny infant baptism, it is certain that many of his Lollard followers did. The term "Lollard," like that of "Waldensian," was a general term that encompassed a wide variety of doctrine and practice. While many of the Lollards retained infant baptism, it is certain that others did not.

History of the English Bible

What was John Wycliffe’s view of baptismal regeneration?


Cokernel of group homomorphism

Question: We know $H=\{ (1),(12) \}$ is subgroup of $S_3$. Consider inclusion '$\varphi: H \hookrightarrow S_3$', this is clearly group homomorphism. Prove that coker$\varphi$ is trivial. I can't understand how to apply universal property of cokernel to this homomorphism $\varphi$.
Comment: One definition of the cokernel of a group homomorphism is the quotient of the codomain of the map by the normal closure of the image. The normal closure of the subgroup $H$ of $S_3$ is the whole of $S_3$, so the cokernel is trivial.
Answer: The cokernel of $\varphi$ is, by definition, initial among all morphism $\psi: S_3\to G$ such that $\psi\circ \varphi$ is the trivial morphism. So you need to prove that if $\psi\circ \varphi$ is trivial then $\psi$ is trivial. Note that $\psi\circ \varphi$ is trivial if and only if $H\leq \ker(\psi)$, so it suffices to prove that any normal subgroup of $S_3$ containing $H$ must be equal $S_3$ itself.
Comment: I don't understand your question, can you clarify?
Comment: We want to prove that $\psi$ is trivial, so it suffices to prove that its kernel is equal to $S_3$.
Comment: We *don't* conclude that $im(\varphi)=S_3$. We want to prove that $\ker(\psi)=S_3$ if $H\leq \ker(\psi)$, but of course $H\neq \ker(\psi)$ since $H$ is not normal.
Answer: Given a group homomorphism $f : A \to B$, it is easy to see that $\operatorname{coker}(f) = B / [f(A)]$, where $[ - ]$ denotes the normal closure of a subgroup. In the language of category theory, more formally, $\operatorname{coker}(f)$ is the qoutient homomorphism  $p : B \to B / [f(A)]$.
To see this, let $q : B \to C$ be any homomorphism such that $q \circ f = 0$. This means $f(A) \subset \ker(q)$, thus $[f(A)] \subset \ker(q)$ because kernels are always normal subgroups. Therefore $q$ can be written as $q = \bar q \circ p$ with a unique homomorphism $\bar q :  B / [f(A)] \to C$.
Now let us look at $[H]$ in $S_3$. The only non-trivial normal subgroup of $S_3$ is the alternating group $A_3$, but certainly $H \not\subset A_3$. Thus $[H] = S_3$ which proves your claim.
Comment: @batuhan,  Here normal closure of a subgroup $H$ means the smallest normal subgroup $N$ containing $H$.

Cokernel of group homomorphism


Scrolling a Gallery enables pressed state and removes click listener from subitems

Question: I have a gallery of fairly complicated items. Each item is composed of an image and 2 buttons.  When the gallery loads everything works, the buttons do what they are supposed to, and the pressed state for the buttons happens only on actual press of the buttons.
However as soon as I scroll the gallery, the buttons stop working and clicking anywhere enables the pressed state for the buttons.
I have tried embedding everything in a LinearLayout that doesn't pass on OnDown events as per this answer however, this just blocks click events.
I am aware that Gallery is not the ideal widget for complicated layouts like this, but I am wondering if there is a better workaround for this issue.
UPDATE:
I will try to explain the architecture a bit. I have a FragmentActivity which contains a ListFragment, which is made up of just a ListView.
The ListView is made up of groups of smaller elements(Bettable) along with some meta information. These groups are implemented as Gallerys. Specifically
I have extended Gallery (called OneGallery), that does several things, it makes sure that only one item is scrolled at a time, and also
transforms the gallery items as the scrolling is happening. Here is the code for that
Here is the adapter for the Gallery
And here is the code for the Bettable layout
Comment: Can you post some code? Its really hard to judge whats happening at your end.
Comment: I added some explanation and code in the update! Thanks.
Answer: Try to add a new wrapper layout around the child view and override the setPressed. The gallery will stop passing its state on the children and the mentioned undesired behavior that you describe will be fixed.
Answer: This is views recycling. Try to use ViewHolder pattern and set up item state for every getView call. If you want to do that you must hold view state in your complex object. For example your complex object contains TextView, ImageView and CheckBox
<code>public View getView(int position, View convertView, ViewGroup parent) {

    ComplexObject co = objects.get(position);

    // A ViewHolder keeps references to children views to avoid unneccessary calls
    // to findViewById() on each row.
    ViewHolder holder;

    // When convertView is not null, we can reuse it directly, there is no need
    // to reinflate it. We only inflate a new View when the convertView supplied
    // by ListView is null.
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_item_icon_text, null);

        // Creates a ViewHolder and store references to the two children views
        // we want to bind data to.
        holder = new ViewHolder();
        holder.text = (TextView) convertView.findViewById(R.id.text);
        holder.icon = (ImageView) convertView.findViewById(R.id.icon);
        holder.checkbox = (CheckBox)convertView.findViewById(R.id.checkbox);
        convertView.setTag(holder);
    } else {
        // Get the ViewHolder back to get fast access to the TextView
        // and the ImageView.
        holder = (ViewHolder) convertView.getTag();
    }

    // Bind the data efficiently with the holder.
    holder.text.setText(co.getText());
    holder.icon.setImageBitmap((position & 1) == 1 ? mIcon1 : mIcon2);
    holder.checkbox.setChecked(co.isChecked());

    holder.checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
                    co.setChecked(isChecked);
                }
            });

    return convertView;
}

protected class ViewHolder{
    TextView text;
    ImageView icon;
    CheckBox checkbox;

}
</code>
Hope it will be helpful
Comment: Unfortunately gallery does not actually recycle views, so this cannot be the reason. I use viewholders in other places of course.


How to check if URL/ IP belongs to a zeus bot

Question: I have a set of URL's which might be Zeus hosts / C&C servers since my security appliance says so. Is there a way to check if these really belong to Zeus?
Answer: Providing that you are looking for information already analyzed, and your question is not about the technical ways to identify a Zeus C&C Server, you can look at the following places:

malwaredomainlist.com
malwaredb.malekal.com
exposedbotnets.com
scumware.org
malc0de.com
cybercrime-tracker.net
vxvault.siri-urz.net
nothink.org
botnet-tracker.blogspot.ch
atlas.arbor.net
marworm.com
zeustracker.abuse.ch (Zeus botnet tracker)
alienvault.com

Note that you can also use those places to look for many other threats / malicious activities than Zeus.
Answer: First, you can look at the abuse.ch zeustracker list.
Second, note that the abuse.ch list is the primary source for the iblocklist.com zeus list.  You may also wish to look through some of the many other malware lists on iblocklist.com to check for other malware sites.
Separately, you can check to see on what basis your security appliance is making the determination - is it using a list (perhaps one of these)?  If it is using a list, which one, and how often does it update it?  Is it using traffic analsis (like Snort would) instead?
Answer: When I get alerts of possible zeus infection from the security appliances, this is what I usually do:

check the URL with zeustracker
if the URL is not in the zeustracker db, check on virustotal
if there is detections, likely this is a malicious connection
Run a tcpdump on the connection to check the packets

zeustracker has a guide showing how to identify zeus malware, go take a look


What short story (or essay?) describes beings in extreme detail, who turn out to be humans?

Question: I've been looking all morning for a short story or essay I read in high school. The writing was overly detailed and abstract describing these 'things' you thought to be aliens by their odd behavior, but the end reveals they are actually humans.
Comment: When were you in high school? Knowing when the story came out (or at least how old it has to be) helps a lot but we have no way to know how old you are :D
Comment: I've seen this theme done a number of times. Most recently the *Planet Construction Kit* did it as an example of how we over-explain things in science fiction.
Comment: it wasn't told from a alien perceptive was it? I recall reading a story where the set up is an astronaut is exploring a ruined civilization that turns out to be human!
Answer: Possibly Body Ritual Among the Nacirema
Story about an anthropologist studying strange beings who turn out to be human, it's a common read in high school and intro uni courses.

The focal point of the shrine is a box or chest which is built into the wall. In this chest are kept the many charms and magical potions without which no native believes he could live. These preparations are secured from a variety of specialized practitioners. The most powerful of these are the medicine men, whose assistance must be rewarded with substantial gifts.  However, the medicine men do not provide the curative potions for their clients, but decide what the ingredients should be and then write them down in an ancient and secret language. This writing is understood only by the medicine men and by the herbalists who, for another gift, provide the required charm.

You can read it here.
Comment: Well, more-specifically, they turn out to be "americaN".
Comment: True, this may be too specific, but there aren't any other answers so I thought I'd take a shot at it


Will the Linux clock fail at January 19, 2038 3:14:08?

Question: I am a bit concerned about this. It's called the "year 2038 problem". Is the Linux kernel or Ubuntu ready to handle dates after this yet, as of 12.04?
Comment: Have you tried setting your clock to something like January 19, 2038 3:14:07 and wait a second?
Comment: The bug was already fixed.
Comment: Let's assume this problem exists and is not fixed yet. 12.04 will not be supported forever, so you and all other people will be on an updated distribution until this happens, since there are many years between. Updating is easy. One of these updates will surely contain a fix. So there is no reason to be concerned, but this is indeed an interesting question.
Comment: @hmayag: I wasn't thinking "toaster," more like "traffic light controller." Those things are a bit more rugged than consumer-grade electronics, and could easily exceed that lifespan (with *part* replacements, but possibly without upgrades) - IIRC, there were some issues with such 1980s electronics just after Y2K.
Comment: The system clock won't (not on a reasonably recent kernel anyway); some data structures (and the programs using it) might exhibit anomalous behavior. In my opinion, this will be a problem with embedded devices - those are much less likely to be running current code.
Comment: @Piskvor you are making an implicit assumption that such devices have an operating life that will exceed 25 years of continuous operation.
Comment: @Piskvor Yes, I see your point. Infrastructure components like those you describe can certainly provide a valid reason for concern.
Comment: Just 32-bit ones. Or at least, ones that use 32-bit timestamps.
Answer: No, it will not fail. In the worst case, from the viewpoint of a programmer it will work as expected: it will be reseted to date 1901-12-13 20:45:52:

This in case you will not update your current distributions until this happens. "Updating is easy. One of these updates will surely contain a fix." like chocobai said.
I remember that it was the same problem/question with 16-bit machines before 2000 and in the end it wasn't any problems.
A solution from Wikipedia:

Most operating systems designed to run on 64-bit hardware already use signed 64-bit time_t integers. Using a signed 64-bit value introduces a new wraparound date that is over twenty times greater than the estimated age of the universe: approximately 292 billion years from now, at 15:30:08 on Sunday, 4 December 292,277,026,596. The ability to make computations on dates is limited by the fact that tm_year uses a signed 32 bit int value starting at 1900 for the year. This limits the year to a maximum of 2,147,485,547 (2,147,483,647 + 1900). While this solves the problem for executing programs, it does not solve the problem of storing date values within binary data files, many of which employ rigid storage formats. It also doesn't solve the problem for 32-bit programs running under compatibility layers and may not solve the problem for programs that incorrectly store time values in variables of types other than time_t.

I use Ubuntu 13.04 on 64-bit and, by curiosity, I changed manually the time to 2038-01-19 03:13:00. After 03:14:08 nothing had happened:

So there is nothing to be concerned about this problem.
More about:

Year 2038 problem - Wikipedia.
End of Time (Unix) - Numberphile.
Comment: I disagree? from the viewpoint of a programmer a clock isn't supposed to reset, so it _will_ fail
Comment: If it resets, it fails because by "fail" I mean "not work or work incorrectly".
Comment: This discussion in the comments is pointless imo. The question is "Is the Linux kernel or Ubuntu ready to handle dates after this?". Well, it's not capable of handling such dates, so it fail in the context of this question.
Comment: @gertvdijk "Is the" *current/actual* "Linux kernel or Ubuntu ready to handle dates after this?"
Comment: @LinuxDistance This happens from your point of view. But from the viewpoint of a programmer it will work as expected: *it will reset*. It was the same with the end of mayan calendar: the world didn't fail because of this.
Comment: In C, adding `1` to `INT_MAX` is [undefined behavior](https://stackoverflow.com/q/18195715/2738262).
Comment: @Nane Are you a programmer? A clock will not fail from the viewpoint of a watchmaker. Don't you think that the programmers didn't knew about this problem from the beginning? They made it to be like this (for this i said *it will work as expected*).
Comment: This only affects 32-bit systems, right?
Comment: If your internet controlled lightbulb fails to connect to it's master server because it thinks the TLS certificate is "not yet valid" you will consider it broken.
Answer: You can check if your computer's time will crash by using the following Perl script:
#!/usr/bin/perl
use POSIX;
$ENV{'TZ'} = "GMT";
for ($clock = 2147483641; $clock < 2147483651; $clock++) {
    print ctime($clock);
}

If your computer will be fine, you will get this:
Tue Jan 19 03:14:01 2038
Tue Jan 19 03:14:02 2038
Tue Jan 19 03:14:03 2038
Tue Jan 19 03:14:04 2038
Tue Jan 19 03:14:05 2038
Tue Jan 19 03:14:06 2038
Tue Jan 19 03:14:07 2038       <-- Last second in 32-bit Unix systems
Tue Jan 19 03:14:08 2038
Tue Jan 19 03:14:09 2038
Tue Jan 19 03:14:10 2038

If your computer is like mine, it'll wrap around like this:
Tue Jan 19 03:14:01 2038
Tue Jan 19 03:14:02 2038
Tue Jan 19 03:14:03 2038
Tue Jan 19 03:14:04 2038
Tue Jan 19 03:14:05 2038
Tue Jan 19 03:14:06 2038
Tue Jan 19 03:14:07 2038
Fri Dec 13 20:45:52 1901
Fri Dec 13 20:45:52 1901
Fri Dec 13 20:45:52 1901

It could also do this:
Tue Jan 19 03:14:01 2038
Tue Jan 19 03:14:02 2038
Tue Jan 19 03:14:03 2038
Tue Jan 19 03:14:04 2038
Tue Jan 19 03:14:05 2038
Tue Jan 19 03:14:06 2038
Tue Jan 19 03:14:07 2038
Tue Jan 19 03:14:07 2038
Tue Jan 19 03:14:07 2038
Tue Jan 19 03:14:07 2038

Comment: confirmed. if you have a 64 bit machine, then this will be fine. Besides... who of us will have 32 bit only machines still running in the year 2038?
Comment: I went looking for this to illustrate the 2038 problem to a coworker, and 2 years after making the above comment, I have very little doubt that in 2038 we will have 32 bit machines that will fail. Ah, youthful optimism.
Comment: I think you're testing Perl here and not the real operating system in the core. Or are you, with the use of `ctime`?
Comment: @gertvdijk Well, it gives the first output on patched computers, and my Ubuntu laptop gives the second, while the third is from my Debian server.  I didn't actually write the code, it's all over the Internet in the same exact form.
Comment: @James, maybe some unwittingly. There will probably be embedded 32 bit Linux in IoT devices around then, unpatched. End of the world? No. Some trouble in some places? Definitely.
Answer: I wrote and published a short paper on this back in 1996. This included a short C program to demonstrate it. I also had emails with David Mills about similar issues with NTP- the Network Time Protocol. On my Ubuntu 14.04 64-bit laptop the perl code did not exhibit the limitation so the underlying 64-bit libs must have been modified.
However, running my long-ago test code does show the time wraps back to the UNIX Epoch. So not all is well with the 32-bit code from the past.
My 1996 paper, The UNIX time will run out in 2038! has been on my website since around 2000. A variant of this titled "UNIX Time" was published in 1998 in "Year 2000 Best Practices for Y2K Millennium Computing" ISBN 0136465064.
Answer: 64-bit Linux is ready, at least if you are talking about the core OS interfaces (individual applications can of course still screw it up). time_t is traditionally defined as an alias for "long" and "long" on 64-bit linux is 64-bit.
The situation for 32-bit Linux (and the compatibility layer for 32-bit binaries on 64-bit Linux) is much less rosy. It's broken and fixing it  without breaking all existing binaries is not an easy task. A whole bunch of APIs use time_t and in many cases it is embedded as part of data structures, so not only must the APIs be duplicated the data structures they work with must be too.
Even if there is some level of backwards compatibility all binaries that want to get correct time will need to be rebuilt to use the new 64-bit time interfaces.
There has been some work done (see for example https://lwn.net/Articles/643234/ and http://www.sourceware.org/ml/libc-alpha/2015-10/msg00893.html) but afaict we are still a long way from a full solution. It is not clear whether or not there will ever be general purpose 32-bit distributions that are Y2K38 safe.
Comment: They are nearly finished now

Approaching the kernel year-2038 end game
https://lwn.net/Articles/776435/
Comment: The kernel is only one part of the puzzle, glibc and the distributions also have a bunch of work to do.


Can someone how to find this voltage gain neglecting r0

Question: I'm trying to figure out why my professor starts off the way he does when trying to find voltage gain. How he starts off is shown in the last picture. Any explanation would be appreciated.
Comment: Assuming by "last picture" you mean the last four equations, which of them do you already understand? (Also, just as a note, you probably should have simply modified your earlier question to improve it rather than ask something quite similar with these additions.)
Comment: Hey, thanks for replying. I don't understand why he starts by setting Vbe equal to Vs(rpi/rpi+Rs). I know it's voltage division but I'd assume you'd start with Vout being equal to an equation with Vs so you can divide the Vs and get Vout/Vs which gets you the gain. Don't understand why he starts with Vbe and then is able to go to Vo in the second equation.
Comment: Eq1. 1st he derives Vbe based on divider action of Rs and Rpi. | Eq2. He then states a standard general equation for Vout | Eq3. He substitutes Vbe from Eq1 into Eq2. | Eq4 He then rearranges Eq3 to give Vout/Vin = .... .
Comment: @Johanis Well, it's probably just easier to start at the left. Especially since the voltage across \$r_\pi\$ affects something on the right side. Eventually, you'll get the output worked out and when you put the full equation together you can re-arrange it for what you need. But to start, you really do want to know what the voltage across \$r_\pi\$ is and the first equation is fine for telling you that much. Of course, you could start with the second equation and then write the first one down. Do both of them make sense to you?
Comment: @jonk thanks for clearing it up. So essentially it best to start with Vbe due to the fact that it allows us to include rpi in the equation and we want to include rpi because it effects the right side?
Comment: @Johanis It's a simple expression and sticks out. It also takes care of the left side, so you can focus on the right with less distractions. The current source is handed to you on a silver platter, at that point.
Comment: @jonk that makes a lot more sense, thanks.
Answer: To calculate voltage gain, you need to compute the value of Vo/Vs. Your circuit is divided into 2 main parts, one on the left (which has Vs) and one on the right (which has Vo). Looking at the right hand side, the value of every component is known except for Vbe which determines the magnitude of the current source.  Vbe is found on the left side by using the voltage divider formula which is the first equation. The second equation gives the value of Vo from the left side of the circuit (This equation perhaps should have come first). Then it is just a matter of substituting the value of Vbe from the first equation into the second equation which results in the third equation. The fourth equation is simply the third equation with both sides divided by Vs so that the gain, Vo/Vs, is obtained as a single expression.


SEM and multiple item / dimension scale

Question: I have a 120 item, 18 facet, five factor model I am attempting to validate. I have attacked this by attempting to develop single congeneric models for each of the 18 dimensions, but am at a loss as to where to go from there using SEM.  Can I impute facet scores and work with the facets or should I continue with the items within the model (which is very messy)?
Answer: Your model is way too big to ever get a reasonable answer from SEM if you use individual scores. You can calculate (not sure if you mean that by impute, but imputation is usually related to missing data). Most (every?) program will let you save a factor score, or you can calculate them, and then feed these into your confirmatory factor analysis.
What's the sample size?

SEM and multiple item / dimension scale


What spells can be cast while silenced?

Question: I've noticed that, while silenced, certain spells can still be cast, such as Divine Shield. What other spells can be cast while silenced?
Answer: Only spells that grant spell (or total) immunity and have a mana (e.g. not rage, energy or focus) cost associated with them.
Examples are:

Most Warrior, Hunter (and pet) and Rogue abilities (don't use mana as a resource)
Divine shield, Ice Block (grant immunity), Dispersion
All Totems except Spirit Link
Barkskin, Aura Mastery
Any zero-cost abilities, such as active racials, mounts (including paladin and warlock mounts) and items.

It is also worth baring in mind that silencing a Frost Mage will not prevent Water Elemental casts.
Comment: It depends on if the OP is talking about PVE or PVP interrupts/silences. Some warrior abilities cannot be cast while silenced. Such as Demoralizing shout cannot be cast. I'm not sure if you counter spelled a warrior (why?!) if they can still use all of their abilities, but in PVE some boss/mob silences stop a warrior from using similar abilities e.g. Demoralizing shout. Also be worth pointing out, interrupts are different to silences. With interrupts it halts that particular school of magic where as silence stops most magic abilities from all schools, minus immunity spells.
Comment: All shouts (Demoralizing, Challenging, Battle, Commanding), Rallying Cry, Piercing Howl, Intimidating Shout, Taunt, and Thunder Clap are not usable while silenced. Shattering Throw can be interrupted, but being silenced does not prevent you from casting it.  So really, warriors get pretty gimped by being silenced.
Comment: @Jared I think thunderclap is another ability affected by silence as well, although I've never paid much attention to warriors.
Comment: I know a Warrior's Throw can be interrupted. Can it be cast while silenced? Also, is Anti-Magic Shell one of the "grant immunity" moves that can be cast while silenced, or is it an exception?
Comment: I'll just leave it in community wiki mode. Feel free to update.

What spells can be cast while silenced?


Basic D&D without play map and miniatures

Question: I'm busting out some basic D&D for some my gaming group. We primarily play pathfinder. Playing without a tactical map and figures is going to be a shock to all of us. My main questions are how movement is handled without a map or figure? I simply don't understand how to make all this work. Do I simply just make it up? How is distanced done? I'm the DM for this session. I'm completely flabbergasted...lol.
Comment: Just cause you don't have a grid map, doesn't mean you can't mark locations in a sketch. Also, the basic rules do allow for a map of you wish to use one
Comment: @GMNoob I'm concerned about the tag edit of adding [dnd-5e] - did the author say they were playing that? (It looks like there might be some comments that have disappeared.)
Comment: Which edition? There are at least 2 games now being identified as "Basic D&D" are you talking about 5e? Or the classic version?
Comment: @chuck 5e can and does work with a map grid, all powers listed are in 5ft increments 5ft = 1sq.
Comment: @doppelgreener Since the OP never returned to clarify that point (they haven't been seen since four days after posting this), it may never be properly fixable. Since it's highly unlikely that they were going from PF to Basic D&D (1981/3), closing it as a duplicate of a Basic D&D (5e) question is *probably* the safest bet. It's also most likely to help future searchers. I agree it's distasteful though. :|
Comment: @SevenSidedDie The dupe closure's fine. People can arrive here and go there. Removing the D&D 5e tag doesn't really compromise anything in this setup.
Comment: @doppelgreener Not disagreeing with the tag change, since yeah, it works still. (And that Q&A works for most editions of D&D one would attempt this in, anyway.) We're on the same wavelength then.
Comment: @SevenSidedDie I believe we are!
Answer: Yes, you simply make it up. The trick is that you not only have to make it all up but keep it consistent and communicate it all clearly to your players. They have to be able to visualize the whole setup of a scene: where everyone is, what objects are there, what opportunities and/or hindrances those objects (may) present to them, what they see, what they hear, smell, and so on (because visually hidden stuff might be hinted at by the other senses, obviously.)
Of course, at the same time, you have to keep it balanced to avoid bogging down your game with listing countless irrelevant details. You'll have to establish a common understanding with the party, learn what your players know about the setting (or its inspiring real-life era and setting), and bring everyone to an equal level... so that when you say "it's an average innhouse" everyone knows what that implies in your world (a stove or two? a fireplace? a bar, or proper tables, or just barrels cut in half, turned upside down for both tables and seating? a few waitresses? barmaids? an innkeeper? lots of large windows, or just a few holes in a several feet wide wall?) ...and so on. Do draw their attention to what's important, what's unusual, sum everything else up, and allow player input based on assumed information (for example, if you haven't mentioned that there's a cellar, but someone assumes there's one, because all the inns they've ever visited had one, let this inn have one as well, and the next time when there isn't one, mention that explicitly.)
Imagine the scene, and communicate it briefly and effectively. If necessary, update your players round by round about the meaningful and important changes taking place -- again, briefly (in a short sentence or two) and effectively. Use your descriptions to establish mood as well -- as that may even influence combat.
Answer: My key advice is: over-describe. Anticipate player questions, and always give them options in your answers.
For example: "Can I cross the cave and reach the kobold with one move?"
Bad answer: "No."
Acceptable answer: "Only if you run, which will mean some penalties."
Best answer: "Only if you run, but the wrecked altar would be a good place to duck for cover after a standard move."
Be very forgiving with movement rates. Seriously, don't sweat the last ten feet. No-one is going to care if the PC or the monster moved a few feet more than they should have.
Describe with relative locations, not distances. "You're in melee range of this monster"..."You're far away from the lever on the wall".
Always give the players the best case answer. Again, anticipate what they're actually thinking. "How many orcs can I hit with my Burning Hands?"..."If you move out from behind the rock, all of them. If you stay put, probably only about half."
Answer: If the encounter is to be (a) long enough and (b) where positioning matters, then we draw a crude sketch of the location map on a single sheet of papers, and mark the players/npcs with single letters there, updating it with pencil and eraser.
Otherwise, just keep in mind some distances - often, the only thing that matters is the separation "he's next to me/I can reach him in a move action/In range for ranged attack/far away", and people can do that in their heads. Sometimes there will be disagreements where one player imagines X to be in range and GM thinks it out of range, but just make a decision and don't waste time and emotions on such cases.
Answer: Squares are measured in 5ft, so you give your players the distance between them and their opponents. Then based off that you determine if they can reach their opponents in one round or two, and if they can make full round attack actions or not. Then allow the players to specify any sort of combat positioning they wish to take, such as flanking, cornering, or maneuvering away from other opponents.
Think of the encounter as very two dimensional, just let the players choose how they wish to divide themselves up among their opponents. It actually helps speed combat up and puts more focus on role playing and player involvement.
Answer: In general, when running without tabletop (or whiteboard) combat maps...
First, I describe terrain.
Next, I make certain I know where the PC's and Badguys are.
I then describe which features the PC's are near and the visible badguys are near.
I also then keep track of progress by distances, making stuff up on the fly as needed.
As an example, the simplest case - a hallway fight. I look at the dungeon map; it's a 5' wide hall. I ask the party for party order. In a 5' hall, logic says one swung or two pokey weapons up front; Poles and spells from the second; spells from the 3rd back.  Once I know who's where, it's a matter of keeping track of distances.
I also tend to get into ceiling height issues with bows when doing this. A bowman can't conveniently shoot over the front rank. (An 8' ceiling limits arrows to about 120' from a front rank human.)
In a more open case — a room with nothing but the badguys — I let the players pick line abreast, possibly in 2 ranks. And as badguys enter the fray, I loosely track left-to-right positions.
In a more complex fight, I may have a copy of the map, and mark in pencil who is where, and then describe. Yeah, it's kind of cheating, but it makes life easier.


Detect supported audio encoders on Android to prevent crash "The given audio encoder 2 is not found"

Question: When an Android device does not support a mandatory audio-encoder, you get:
(X=numeric index of the encoder)
E/MediaProfiles(4048): The given audio encoder X is not found
 A/AudioSource(4048): frameworks/base/media/libstagefright/AudioSource.cpp:58 CHECK(channels == 1 || channels == 2) failed.
 A/libc(4048): Fatal signal 11 (SIGSEGV) at 0xdeadbaad (code=1)
In native code. No Exception to react to. App is just force closed.
Is there any way to query an Android >3.x device if
AAC
AMR-NB and
AMR-WB
are actually supported?
Documentation ( http://developer.android.com/guide/appendix/media-formats.html )
says that these are core media formats and thus always supported.
Some actual and common phones out there (of major brands) don't.
MediaCodec.createByCodecName(String name) and
Get supported Codec for Android device
only works with API16=Android 4.1 but the devices in question are 4.0.x .
It also does not list AMR-NB and AAC.
Comment: I've been accessing the fields of the MediaRecorder.AudioEncoder.class via reflection, then cycling through them setting up the mediarecorder. If it fails i loop through to the next one, then when i have success i save the int of the encoder to a sharedsetting to speed up the process.
Answer: On your Android device, the media profiles/capabilities are stored in a config file called media_profiles.xml(on ICS/4.0).
Normally, this file is located in /etc folder on the device.
So what you could do is

Connect your device to pc and pull /etc/media_profiles.xml file using adb pull command
Examine the AudioEncoderCap properties. There will be multiple entries for each capbility that is advertised.
for ex:
AudioEncoderCap name="aac" enabled="true"
        minBitRate="8192" maxBitRate="96000"
        minSampleRate="8000" maxSampleRate="16000"
        minChannels="1" maxChannels="1"
If the 'enabled' flag is set to "true" as above, then that capability should be supported by the device. If it is not supported, the 'enabled' flag will be set to "false".

AFAIK, the media codecs framework introduced on jb (4.1) read this/similar config file to expose the device capabilities to the application layer.
Hope this helps.
Thanks!
Comment: The Android app has to detect if a user's device supports a given codec. No PC or ADB possible.


Scroll wheel zoom is unmanageble

Question: There seems to be no way to limit the speed of the zoom using the scroll wheel.  It behaved better after selecting 'auto depth' but after a restart even that had no effect.  The zoom function is a major navigational aspect and needs to be more refined.  Is there some setting or feature I'm missing here?
Comment: Auto Depth had no effect after restarting because new user preferences configuration likely wasn't saved. Check also if Pivot point is set to something other than 3D cursor, e.g. set it to Median Point.
Comment: To have more control over zooming do it with the *Ctrl+Mouse Scroll*. Hold *Ctrl* and *Mouse Scroll* then drag the cursor up or down.
Comment: You should be able to change your scroll wheel sensitivity at the OS level. Take a look in your system prefs.
Comment: @Mentalist While changing the scroll wheel sensitivity from the OS level may solve this problem, it is bad practice to change it every now and then, say to surf through the internet normally.
Answer: Had the same issue recently on Windows. I usually use Linux, but opened a file I'd been working on in Windows, and the scroll wheel zoom was WAY OFF!
Basically, with the panel in focus, hit the "Home" key. Found this answer HERE.
Answer: With Blender on Windows, you may hold ⌃ Ctrl on your keyboard and MMB  while moving the mouse itself up and down rather than the just scroll wheel to get finer control. I seem to be able to zoom in/out slowly and smoothly or quickly like this.

Scroll wheel zoom is unmanageble