Polyethylene glycol

Question: I used a product on my family containing 90 percent Polyethylene glycol. Now I'm reading how Polyethylene glycol can be contaminated with ethylene oxide and also the lower the weight the higher the chance. The Polyethylene glycol in the product I used has no number following and it was a soft cream used for skin care.
I was wondering if someone could explain to me how Polyethylene glycol is safer than ethylene oxide and how exactly is Polyethylene made? I'm very worried that I put a toxic cream on my children one of them who had eczema at the time.
Thank you
Comment: Do not trust random websites. I suspect that widespread misinformation is made for the interest of "bio products" companies. Polyethylene glycol can be synthetized by reaction with ethylene oxide. But ethylene oxide, being far from healthy, is carefully removed from polymers suitable for human use (and it's not hard to do, being it a gas). I would say not to worry
Comment: While polyethylene glycol [PEG] is safe for human consumption, and the worst part of a colonoscopy,  ethylene glycol is not. It is metabolized to oxalic acid which is toxic.
Comment: @The_Vinz: I like your comment. Also, any remaining ethylene oxide may be converted to ethylene glycol and would be okay to external applications. Lynn has nothing to worry about.
Comment: Agree with @The_Vinz, also, polyethylene oxide (or polyethylene glycol) has nothing to do with polyethylene and is only formally related to ethylene glycol as well. The name polyethylene glycol comes from the formal polycondensation of ethylene glycol (which does not work in practice), while the name polyethylene oxide comes from the anionic polymerisation of ethylene oxide (this is the synthesis route used in practice).
Comment: @user55119 Oxalic acid is not toxic in such trace amounts. It is present in a lot of vegetables which are safely edible. Rhubarb, chocolate, spinach, ...
Comment: @Karl: Agreed! I'm well aware. I like all three of them. I intended to point out that the lowest homolog of PEG does not have the same properties as the polymer.
Comment: @user55119 Yes, that's basically a fundamental principle for polymers.
Comment: Thanks you for your responses. After using this cream and then reading many scary articles on polyethylene glycol I have been very worried . I'm ok if it's one of many ingredients in my products but because it was 90 percent I will not be using it again.  It still scares me that it is made from ethylene oxide though
Comment: Lynn, i'd like to know where you are reading about the ethylene oxide.
Comment: I read a article online,  I believe it was  " the dirty dozen" and it said PEGs may be contaminated with ethylene oxide during its production and more. There are other articles that said the same thing.
Answer: Poly(ethylene glycol), commonly known as PEG is non-ionic, hydrophilic, non-toxic, and the most used polymer in wide variety of applications. For example, PEG is the gold standard for stealth polymers in the emerging field of polymer‐based drug delivery (Ref.1). You may find mostly unbiased information about PEG here, which is generally considered biologically inert and safe according to the clinical studies. However, drawback is these studies of clinical safety of PEG are generally based on adults, not children. Nonetheless, at least one study using children have proven it is safe for children as well (Ref.2).
So far, I addressed the suitability of PEG for human consumption. Note that these PEG molecules suitable for human intake have specific lengths such as PEG 3350, which has an average molecular weight of $\pu{3350 g/mol}$ (The structure of PEG is commonly expressed as $\ce{H−(O−CH2−CH2)_n−OH}$). Yet, my argument is if PEG is clear to human intakes, then it should be safer for external applications such as skin creams. To my understanding, among available PEG molecules ($n=1, 2, 3, ..., n$), only toxic one to human is its monomer,  $\ce{H−O−CH2−CH2−OH}$ (when $n=1$), commonly known as ethylene glycol or antifreeze. The apperent toxicity of that molecule is mainly due to its enzymatic oxygenation inside the body to oxalic acid, which produce insoluable calcium oxalate crystals.
As you concern, PEG is the basis of many skin creams. An example of PEG derivative used in skin creams is cetomacrogol 1000, which is the trade name for polyethylene glycol hexadecyl ether ($\ce{-O-C16H33}$) with the general formula $\ce{HO(CH2CH2O)_nC16H33}$ (where $n= 2-20$). When $n=10$, it is named Brij56, and when $n=20$, it is Brij58, etc. Another polyethylene glycol ether commonly used in cosmatic industry is Isoceteth-20, which has the same general formula $\ce{HO(CH2CH2O)_nC16H33}$ where $n$ has an average value of 20. The difference between Isoceteth-20 and cetomacrogol 1000 is use of iso-cetyl alcohol instead of cetyl alcohol. Few examples for cosmetics containing Isoceteth-20 are: Nivea, Aveeno, and  Nu Skin products, among many others. So, I'd be comfortable with using these products, just based on their reputation.
Now, how PEG is synthesized?

The production of polyethylene glycol was first reported in 1859. Both A. V. Lourenço and Charles Adolphe Wurtz independently isolated products that were polyethylene glycols. Polyethylene glycol is produced by the interaction of ethylene oxide with water, ethylene glycol, or ethylene glycol oligomers. The reaction is catalyzed by acidic or basic catalysts. Ethylene glycol and its oligomers are preferable as a starting material instead of water, because they allow the creation of polymers with a low polydispersity (narrow molecular weight distribution). Polymer chain length depends on the ratio of reactants (Wikipedia).

For example, branched PEG haas been recently prepared by Copolymerization of ethylene Oxide and glycidol (Ref.3):

$\mathrm{^{13}C \; NMR}$ of the product mixture shows no presence of unreacted ethylene oxide and glycidol:

References:

Katrin Knop, Richard Hoogenboom, Dagmar Fischer, Ulrich S. Schubert, "Poly(ethylene glycol) in Drug Delivery: Pros and Cons as Well as Potential Alternatives," Angew. Chem. Int. Ed. Engl. 2010, 49(36), 6288–6308 (https://doi.org/10.1002/anie.200902672).
Dinesh S. Pashankar, Vera Loening-Baucke, Warren P. Bishop, "Safety of Polyethylene Glycol 3350 for the Treatment of Chronic Constipation in Children," Arch Pediatr. Adolesc. Med. 2003, 157(7), 661–664 (https://doi:10.1001/archpedi.157.7.661).
Daniel Wilms, Martina Schömer, Frederik Wurm, M. Iris Hermanns, C. James Kirkpatrick, Holger Frey, "Hyperbranched PEG by Random Copolymerization of Ethylene Oxide and Glycidol," Macromol. Rapid Commun. 2010, 31(20), 1811–1815 (https://doi.org/10.1002/marc.201000329).

Polyethylene glycol


Is there any way to temporarily turn off "My Picture" in Gmail?

Question: I use a pic of my late Samoyed dog as "My Picture" when sending Gmail. I had to have him put down (vet's strong recommendation) because his hip dyspepsia and multi-organ failure had my poor dog in chronic pain. Analgesics just did not significantly relieve his pain. While the pic is very sentimental to me, that very cute image is not appropriate for business emails. I know that I can delete the image, when dealing with formal emails, and then upload it again. But I am hoping there is a way to temporarily switch the "My Picture" option off when sending formal emails, and then turn it back on for more casual emailing.
Answer: No, there is no way to temporarily off My Picture in Gmail.
There are only two options. See Gmail Help:

Visible to everyone: Anyone who you email, or who emails you, can see your picture.
Visible only to people I can chat with: Only people you've given permission to chat with you or see when you're online can see your picture.

In your case if you don't want remove picture, choose the second option.


How do you install Windows XP on a computer that has Ubuntu and Windows 7 installed?

Question: I had a PC with Ubuntu and Windows 7 installed and I wanted to Install Windows XP on it.
I installed it and then used boot-repair to repair the bootloader; I thought that I would get a screen asking whether I wanted to load Windows 7 , Windows XP or Ubuntu, but it only gives me options for Windows 7 and Ubuntu, while XP has disappeared. Any idea?
Answer: If there is no need for a native installation oft Windows XP I'd advice you to use kvm-qemu or hyper-v running XP as a guest OS instead oft wasting a partition for XP. The benefit oft this approach is the that you can keep you XP as as large as really needed and you need not to struggle with bootloaders etc.
Please note that hyper-v must be downloaded from MS and Windows 7 isn't supporting all its features thus it was introduced with windows 8.


QGIS - How to check if a raster has same resolution as another raster with a different CRS?

Question: I have an original raster file called SAM. This has a resolution of 0.0025 pixels, it was obtained using 100m resolution satellite. I have another raster called Global fire. This has a pixel resolution of 463.3m using a custom CRS. I converted the Global Fire CRS to be the same as the SAM file to see what 463.3m in pixel resolution was equivalent in georeferenced units like the SAM file. This was the value 0.00205... I then did a reprojection of the original raster file SAM to convert its resolution to have a pixel size of 0.00205 to match the Global Fire pixel size.
My question is that is this methodology fine. Have I essentially now converted the SAM to now have a resolution of 463.3m resolution this way. I did this because I couldn't get that custom CRS to go on to the SAM file.
I look at the actual resolution on the screen and it doesn't look too different so I figured I may have done something wrong?
Answer: Seems to be some confusion here. If you have a satellite image at 100 m resolution, then that's its resolution. Each pixel is 100 m. (saying "resolution of 0.0025 pixels" does not make sense). If you want to know the equivalent size of a pixel from some other coordinate system, just convert the units. (No need to reproject).
When you say: "I converted the Global Fire CRS to be the same as the SAM file" I hope you did NOT set the projection. That's the most "popular" error with CRS conversions.
If you need to do some coordinate transform you have to know exactly what the current CRS are for both rasters. With more details regarding both rasters someone will surely be able to offer more help.


Can a userscript delete cookies from a given domain?

Question: Can Greasemonkey delete cookies from a given domain? If so, how?
Comment: I want to automate it for a site that I need to clear cookies from repeatedly.
Comment: In Firefox you can already delete cookies from whichever domain you want, as well as blocking cookies from a specific domain.  You can find this in the "Options..." dialog.  Is there a particular reason you want a Greasemonkey script for this?
Answer: There are major limitations on what Greasemonkey can delete. Other tools may be better for what you want, see below.  But, if all of these conditions are met:

The cookies you want to delete are on the current page's domain.
They are not "Secure cookies".
You loop through the possible paths, including /, a blank path, etc.
No cookies are set by javascript, after the page loads.
The thing tracking you really is a "cookie".  Many websites use a variety of other techniques, including LSO's, local storage, etc.

THEN, the following code will delete them:
//--- Loop through cookies and delete them.
var cookieList  = document.cookie.split (/;\s*/);

for (var J = cookieList.length - 1;   J >= 0;  --J) {
    var cookieName = cookieList[J].replace (/\s*(\w+)=.+$/, "$1");

    eraseCookie (cookieName);
}

Where eraseCookie() is:
(Note that this eraseCookie gets many more cookies by attempting all possible paths and the most likely sub-domains.)
function eraseCookie (cookieName) {
    //--- ONE-TIME INITS:
    //--- Set possible domains. Omits some rare edge cases.?.
    var domain      = document.domain;
    var domain2     = document.domain.replace (/^www\./, "");
    var domain3     = document.domain.replace (/^(\w+\.)+?(\w+\.\w+)$/, "$2");;

    //--- Get possible paths for the current page:
    var pathNodes   = location.pathname.split ("/").map ( function (pathWord) {
        return '/' + pathWord;
    } );
    var cookPaths   = [""].concat (pathNodes.map ( function (pathNode) {
        if (this.pathStr) {
            this.pathStr += pathNode;
        }
        else {
            this.pathStr = "; path=";
            return (this.pathStr + pathNode);
        }
        return (this.pathStr);
    } ) );

    ( eraseCookie = function (cookieName) {
        //--- For each path, attempt to delete the cookie.
        cookPaths.forEach ( function (pathStr) {
            //--- To delete a cookie, set its expiration date to a past value.
            var diagStr     = cookieName + "=" + pathStr + "; expires=Thu, 01-Jan-1970 00:00:01 GMT;";
            document.cookie = diagStr;

            document.cookie = cookieName + "=" + pathStr + "; domain=" + domain  + "; expires=Thu, 01-Jan-1970 00:00:01 GMT;";
            document.cookie = cookieName + "=" + pathStr + "; domain=" + domain2 + "; expires=Thu, 01-Jan-1970 00:00:01 GMT;";
            document.cookie = cookieName + "=" + pathStr + "; domain=" + domain3 + "; expires=Thu, 01-Jan-1970 00:00:01 GMT;";
        } );
    } ) (cookieName);
}

Optional function, for information or debug:
function listCookies () {
    var cookieList  = document.cookie.split (/;\s*/);

    for (var J = 0, numCookies = cookieList.length;   J < numCookies;  ++J) {
        console.log ("Cookie ", J, ": ", cookieList[J]);
    }
}

Your GM script can also use iFrame tricks to delete cookies on third-party domains, but GM is not the best way to handle cookies, in general.
Don't be fooled by any other claims, Greasemonkey and javascript simply cannot delete a cookie unless all of the conditions, listed at the top of this answer, are met.  Note that javascript and Greasemonkey cannot even see all the cookies on a page.
Greasemonkey is not the best tool for this, although it may be adequate for select situations.
Here are some far more powerful solutions:

Use Selective Cookie Delete.  It keeps the cookies you want and deletes the rest.  It does this at the push of a very handy button or automatically when Firefox closes.  Both white-lists and black-lists are supported.
Use BetterPrivacy for sneakier LSO's.
Run CCleaner at least once a week, to exorcise a broad spectrum of tracking and cruft.
For powerful, custom, fully-automated cookie removal that does not have the severe limitations that Greasemonkey has, and that runs more often than Selective Cookie Delete, you can write your own browser extension.
Comment: Thanks a lot! Finally a cookie deletion script that works!
Answer: You should be able to delete cookies for the currently open site.  Have a look at the Cookie Zapper script, this may do what you want and if not the source will probably point you in the right direction.
Comment: HTTP-only cookies cannot be deleted using that method (in Greasemonkey).


Atomic shielding

Question: Well the core of the atom has a positive net charge . For atoms with many electrons there is a negative electron cloud . How do valence electrons even exist? The electron cloud is closer to the orbital of the valence electron so they repel it more than the nucleus attracts it . *Where I mean electron cloud I mean all the subshells before the valence electron.
Comment: "The e- cloud is is closer to the orbital of the valence e-s , so they repel it more than the nucleus attract" The implication is not correct that's why. But the core cloud do shield nucleus, making it effectively less charged, that's why valence e-s are easy to remove.
Comment: I think the problem is with your assumption that electron-electron repulsion is more that electron-nucleus attraction. I don't think that is the case, and valence electrons are indeed held by the nucleus, although they are less bound than the inner electrons.
Answer: If you don't include the valence electrons, the electron cloud has less number of electrons than the number of protons in the nucleus (a (non-bonded, non-ionised) atom is electrically neutral).
The net positive charge is greater than the net negative charge if you remove the valence electrons. Even though part of the electron cloud is closer, the electron cloud surrounds the nucleus symmetrically and so equal part of it is also further away than the nucleus. It effectively acts as if it's charge were concentrated at the center for the most part.
In other words, the net electric charge for an atom, with, say, 2 valence electrons, would be +2 without the valence shell. So there is flux directing the valence electrons towards the nucleus (remember that the electric flux depends only on the net charge enclosed, not the distribution of charge)

Atomic shielding


White of an egg

Question: What happens when you dissolve white of an egg in water?
Firstly, what's white of an egg? Is it the white part? Or implies whole of an egg? I couldn't relate much of it with colloids, either.
Answer: The white clear liquid in the egg is nothing but albumin. It helps in supplying nutrition to the yolk and gives strength to the yolk during the formation of chicken. White part doesn't imply whole of an egg.
       The composition of that white liquid is 90% water and 10% protein.
       If you dissolve it in water, then it is nothing but a colloidal solution. We can call it as emulsion as it is 'protein in water '.
    Hope helpful..
Comment: @user208322 If you have a different question, please post it as a new question, not a comment.
Comment: Thanks a lot! That was quite simple. I got one more question for you: what happens when you pass sulfur vapors through cold water.
Comment: The white of the egg, albumin, should be dissolved in cold water as in hot water it clogs.

White of an egg


How do I restore a previous version of the "docsethomepage.aspx" of a document set content type in SharePoint Online?

Question: I want to go back to a previous version of the homepage of a document set content type in a specific document library called "Reklamationen". The content type is called "Reklamation".
I couldn't find the file in the document library. It is also hard to find files there because it has over 100.000 files stored in it. It is also not in the SiteAssets in the site contents. This is all in classic UI.
Answer: Not sure if this is the same for SP Online, but for SP 2016, the Doc Set home page is in a folder named after the content type, inside the document library's hidden "Forms" folder.
So if SP Online works the same, your Doc Set home page would be in
<code>/your-site/Reklamationen/Forms/Reklamation/DocSetHomePage.aspx
</code>
I don't know exactly how you would go about reverting to a previous version (Powershell?), but that's where I think you will find it.
Comment: Thanks! You are correct with the location. But I want the UI to be like a list where I have the context menu available with the version history in it. Is there a way to unhide the folder to be visible in the document library?
Comment: Not that I know of, that's why I was speculating that you might have to use Powershell to be able to get to the file in a way that you can revert the version.


Abstract classes vs. interfaces vs. mixins

Question: Could someone please explain to me the differences between abstract classes, interfaces, and mixins? I've used each before in my code but I don't know the technical differences.
Comment: Retagged as 'oop' because it seemed more relevant than tag 'concepts'.
Answer: Abstract Class
An abstract class is a class that is not designed to be instantiated. Abstract classes can have no implementation, some implementation, or all implementation. Abstract classes are designed to allow its subclasses share a common (default) implementation. A (pseudocoded) example of an abstract class would be something like this
abstract class Shape {
    def abstract area();  // abstract (unimplemented method)
    def outline_width() = { return 1; }  // default implementation
}

A subclass might look like
class Rectangle extends Shape {
    int height = width = 5;
    def override area() = { return height * width; }  // implements abstract method
    // no need to override outline_width(), but may do so if needed
}

Possible usage
def main() = {
    Shape[] shapes = { new Rectangle(), new Oval() };
    foreach (s in shapes) {
        print("area: " + s.area() + ", outline width: " + s.outline_width());
    }
}

If a subclass does not override unimplemented methods, it is also an abstract class.
Interface
In general computer science terms, an interface is the parts of a program exposed to a client. Public classes and members are examples of interfaces.
Java and C# have a special interface keyword. These are more or less an abstract class with no implementation. (There's trickiness about constants, nested classes, explicit implementation, and access modifiers that I'm not going to get into.) Though the part about "no implementation" doesn't fit any more in Java, they added default methods. The interface keyword can be seen as a reification of the interface concept.
Going back to the Shape example
interface Shape {
    def area();  // implicitly abstract so no need for abstract keyword
    def outline_width();  // cannot implement any methods
}

class Rectangle implements Shape {
    int height = width = 5;
    def override area() = { return height * width; }
    def override outline_width() = { return 1; }  // every method in interface must be implemented
}

def main() = {
    Shape[] shapes = { new Rectangle(), new Oval() };
    foreach (s in shapes) {
        print("area: " + s.area() + ", outline width: " + s.outline_width());
    }
}

Java and C# do not allow multiple inheritance of classes with implementation, but they do allow multiple interface implementation. Java and C# use interfaces as a workaround to the Deadly Diamond of Death Problem found in languages that allow multiple inheritance (which isn't really that deadly, if properly handled).
Mixin
A mixin (sometimes called a trait) allows multiple inheritance of abstract classes. Mixins don't have the scary association that multiple inheritance has (due to C++ craziness), so people are more comfortable using them. They have the same exact Deadly Diamond of Death Problem, but languages that support them have more elegant ways of mitigating it than C++ has, so they're perceived as better.
Mixins are hailed as interfaces with behavioral reuse, more flexible interfaces, and more powerful interfaces. You will notice all these have the term interface in them, referring to the Java and C# keyword. Mixins are not interfaces. They are multiple inheritance. With a prettier name.
This is not to say that mixins are bad. Multiple inheritance isn't bad. The way C++ resolves multiple inheritance is what everyone gets all worked up about.
On to the tired, old Shape example
mixin Shape {
    def abstract area();
    def outline_width() = { return 1; }
}

class Rectangle with Shape {
    int height = width = 5;
    def override area() = { return height * width; }
}

def main() = {
    Shape[] shapes = { new Rectangle(), new Oval() };
    foreach (s in shapes) {
        print("area: " + s.area() + ", outline width: " + s.outline_width());
    }
}

You will notice there is no difference between this and the abstract class example.
One extra tidbit is that C# has supported mixins since version 3.0. You can do it with extension methods on interfaces. Here's the Shape example with real(!) C# code mixin style
interface Shape
{
    int Area();
}

static class ShapeExtensions
{
    public static int OutlineWidth(this Shape s)
    {
        return 1;
    }
}

class Rectangle : Shape
{
    int height = 5;
    int width = 5;

    public int Area()
    {
        return height * width;
    }
}

class Program
{
    static void Main()
    {
        Shape[] shapes = new Shape[]{ new Rectangle(), new Oval() };
        foreach (var s in shapes)
        {
            Console.Write("area: " + s.Area() + ", outline width: " + s.OutlineWidth());
        }
    }
}

Comment: To be clear: Mixin\Traits are ways of extending functionality of a class (e.g add methods) without using inheritance.  The answear suggets they are the same thing, but there are some important differences. 1. Mixins may be statefull, traits are stateless 2. Mixins use implicit conflict resolution, traits use explicit conflict resolution (more
http://stackoverflow.com/questions/925609/mixins-vs-traits)
Answer: In general:
An interface is a contract specifying operations, but without any implementation.  Some languages (Java, C#) have baked-in support for interfaces, and in others 'interface' describes a convention like a pure virtual class in C++.
An abstract class is a class which specifies at least one operation without an implementation.  Abstract classes can also provide some parts of their implementation.  Again, some languages have baked-in support for marking classes as abstract and it is implicit in others.  For example, in C++ a class which defines a pure virtual method is abstract.
A mixin is a class which is designed to make implementation of certain functionality easier in subclasses, but which is not designed to be used by itself.  For example, say that we have an interface for an object that handles requests
interface RequestHandler {
  void handleRequest(Request request);
}

Perhaps it would be useful to buffer the requests by accumulating them until we have some predetermined number and then flushing the buffer.  We can implement the buffering functionality with a mixin without specifying the flush behavior:
abstract class BufferedRequestHandlerMixin implements RequestHandler {
  List<Request> buffer = new List<Request>();

  void handleRequest(Request request) {
    buffer.add(request);

    if (buffer.size == BUFFER_FLUSH_SIZE) {
        flushBuffer(buffer);
        buffer.clear();
    }
  }

  abstract void flushBuffer(List<Request> buffer);
}

This way, it's easy for us to write a request handler that writes requests to disk, calls a web service, etc. without rewriting the buffering functionality each time.  These request handlers can simply extend BufferedRequestHandlerMixin and implement flushBuffer.
Another good example of a mixin is one of the many support classes in Spring, viz. HibernateDaoSupport.
Comment: Wait, maybe i'm missing something but isn't BufferedRequestHandlerMixin  an abstract class? How does this differ from a Mixin?
Comment: Great, this is exactly what I needed, thank you. One thing however: could you clarity exactly how mixins "make implementation of some behavior easier in subclasses"?
Comment: Let me know if the example helps.
Comment: mR_fr0g, yes, BufferedRequestHandlerMixin is implemented as an abstract class.  It's common to implement mixins using abstract classes in Java, as the abstract keyword notes that the class is designed for reuse and isn't mean to be used by itself (it also obviously prevents you from using it by itself).
Comment: "An abstract class is a class which specifies at least one operation without an implementation" : not quite true for .NET. For example the following is a valid class definition in c#: "public abstract class Foo { }"
Answer: Since many of guys have explained about the definitions and usage, I would like to highlight only important points
Interface:

To define a contract ( preferably stateless - I mean no variables )
To link unrelated classes with "has a" capabilities.
To declare public constant variables (immutable state)

Abstract class:

Share code among several closely related classes. It establishes "is a" relation.
Share common state among related classes  ( state can be modified in concrete classes)

I am closing the difference with a small example.
Animal can be an abstract class. Cat and Dog, extending this abstract class establishes "is a" relation.
Cat is a Animal
Dog is a Animal.
Dog can implement Bark interface. Then Dog has a capability of Barking.
Cat can implement Hunt interface. Then Cat has a capability of Hunting.
Man, who is not Animal, can implement Hunt interface. Then Man has a capability of Hunting.
Man and Animal (Cat/Dog) are unrelated. But Hunt interface can provide same capability to unrelated entities.
Mixin:

If you want a mixture of both abstract class and interface. Especially useful when you want to force a new contract on many unrelated classes where some of them have to re-define new behaviour and some of them should stick to common implementation. Add common implementation in Mixin and allow other classes to re-define the contract methods if needed

If I want to declare an abstract class, I will follow one of these two approaches.

Move all abstract methods to interface and my abstract class implements that interface.
interface IHunt{
    public void doHunting();
}
abstract class Animal implements IHunt{

}
class Cat extends Animal{
    public void doHunting(){}
}

Related SE question :
What is the difference between an interface and abstract class?
Answer: Reference to Java and given example of Abstract class to provide mixin is misleading.
First of all, Java does not support "mixins" by default. In Java terms abstract class and Mixins become confusing.
A mixin is a type that a class can implement in addition to its "primary type" to indicate that it provides some optional behavior. To speak in Java terms, one example would be your business value object implementing Serializable.
Josh Bloch says - "Abstract classes can not be used to define mixins - since a class can not have more than one parent" ( Remember Java allows only one "extends" candidate)
Look for languages like Scala and Ruby for appropriate implementation of the notion of "mixin"
Comment: With java 8 version,  default methods in interface provides mixing feature.
Comment: Also JavaScript, the most widely used language with the concept of mixins.
Answer: The meaning of 'Mixin' is excellently defined by Joshua Bloch in his effective Java book. An excerpt from the same book:
"mixin is a type
that a class can implement in addition to its "primary type" to declare that it provides
some optional behavior. For example, Comparable is a mixin interface that
allows a class to declare that its instances are ordered with respect to other mutually
comparable objects. Such an interface is called a mixin because it allows the
optional functionality to be "mixed in" to the type's primary functionality."
Answer: Basically an abstract class is an interface with some concrete implementation. An interface is just a contract that has no implementation detail.
You would use and abstract class if you want to create common functionality amoung all of the objects that implement the abstract class. Keeping with the DRY (Don't Repeat Yourself) principle of OOP.
Comment: There's more to it than that. For instance, an abstract class can define abstract protected method, an interface can not. And you can implement any number of interfaces but you can only extend one abstract class (unless your language has multiple inheritance).
Comment: yes there is definitely more to it then what I have described (and to @musicfreak, you should research more because there is a lot on this topic). just trying to give a quick definition for the OP since he stated that he/she wanted something less technical.
Comment: +1 for keeping it simple and to-the-point. Also, n3rd, thanks for the info.
Answer: An abstract class is a class that not all of its members are implemented ,they are left for the inheritors to be implemented.It forces its inheritors to implement its abstract members.
Abstract classes can't be instantiated and thus their constructors shouldn't be public.]
Here's an example in C#:
    public abstract class Employee
    {
        protected Employee(){}
        public abstract double CalculateSalary(WorkingInfo workingInfo);//no implementation each type of employee should define its salary calculation method.
    }

   public class PartTimeEmployee:Employee
  {
    private double _workingRate;
    public Employee(double workingRate)
    {
     _workingRate=workingRate;
    }
    public override double CalculateSalary(WorkingInfo workingInfo)
    {
      return workingInfo.Hours*_workingRate;
    }

}
An interface is a contract to be implemented by a class.It just declare the signature of the members of an implementing class and it has no implementation itself.We usually use interfaces to implement polymorphism,and to decouple dependent classes.
Here's an example in C#:
public interface IShape
{
int X{get;}
int Y{get;}
void Draw();
}

public class Circle:IShape
{
public int X{get;set;}
public int Y{get;set;}

public void Draw()
{
//Draw a circle
}
}

public class Rectangle:IShape
{
public int X{get;set;}
public int Y{get;set;}

public void Draw()
{
//Draw a rectangle
}
}


Installing Ubuntu 16.04 - Out of Range issue (in Skylake)

Question: I'm trying to install Ubuntu Studio in a brand new machine. It has UEFI and Grub2.
Problem is that after a Ubuntu (Studio) splash screen I get a "signal out of range" error. And all I can do is press ctrl+alt+F1 to log in without X.
--
So, I read things like disabling UEFI and Fast Boot and so I did. That just changed the look and feel of the grub2 menu. But the Out of Range issue remains.
--
Then, some people talks about using nomodeset. But I just can't find where to put that.
--
Other people says "edit /etc/default/grub and uncomment the GRUB_GFXMODE=640x480 line". So I did. The I'm supposed to run:
sudo update-grub2
Well, that last line won't work. I'm getting this error:
failed to get canonical path of /cow
I understand this has something to do with mounting something. Not sure if my new SSD disk (that I didn't format at all, is brand new). Any clue?
--
Also some people talks about using grub-repair but that seems to work only for people already having a running X environment. And I don't. If I burn a recovery CD all I get is the grub screen.
--
Finally, there're the ones who talks about compatibility issues with skylake, and mention adding this param somewhere: i915.preliminary_hw_support=1
And I just don't know what are they talking about.
--
More that all I'd like to understand where is supposed grub to live? In my pendrive? Or is it part of the kernel now? I just don't get it.
Thanks in advance.
--
My hard:
. ASUS z170-A mother
. nvidia gtx 960
. samsung ssd
Answer: News: I was able to run from the live-pendrive and install by using the nomodeset param. I learned how here:
Trying to install Ubuntu 14.04, monitor says mode unsupported/out of range
Bsically, pressing the "e" key in the grub menu and adding that string after the words "quiet splash".


new washer installed in my condo, and water is backing up and overflowing on the floor through the hose

Question: I have a plumber came in last wednesday to replace my faucet in the bathroom shower, because the water coming from the shower, both hot and cold was not mixing properly, he replaced the faucet with a one piece handle faucet. everything seems to be fine. He also installed a new washer for me that is just beside the bathroom and the hose where the water suppose to drain out is escaping on the floor. Are you able to tell me why something like this is happening when the washing machine is releasing the water. Is it that the plumber did not hook up the hose properly,or does this have any connection with fixing the new faucet.
Comment: Where is the water escaping from? some photos might be helpful, since we can't see it from here.
Comment: Is the drain hose from the washer backing out of the drain pipe, then popping back down when the washer is drained? This can be infuriating to figure out because when the machine isn't actively dumping, you'd never know it was doing it.
Answer: Older washing machines required 1 1/2" pipe.  Newer machines drain water faster than older-style washers, so you may need to install a 2 inch (50mm) drain or get a washing machine that drains slower, like the old one.
I've seen this problem before.
Comment: I see why draining washers into laundry tubs is a good idea now.  It's a built in resevoir.


Where can I download SharePoint Foundation 2010 without SP2

Question: I need to set up a development environment for a site that is currently running SP1. I set up my dev environment with SP2010 SP2 and then I found out the hard way that you cannot restore a backup from an older version onto a newer version. Upgrading the production site to SP2 is an option but that needs to be scheduled and tested and might be a month or two out. I would like to be able to develop in the mean time. Is there any way to downgrade my SP 2010 foundation SP2 to SP1, or is there an installer that has just the base SP Foundation 2010 or SP Foundation 2010 plus SP1? I can only find the one that includes SP2 updates on the Microsoft download web site.
Answer: i think its too late to get the foundation with sp1. i checked the msdn but over there its already sp2. best option to contact MSFT and get the old bits from there.
That's why i always say, keep the copy of exe files until the product life.
Answer: Use this link for downloading Sharepoint foundation 2010 SP1 http://www.microsoft.com/en-in/download/details.aspx?id=26640
Comment: This is just the Service Pack, no use without a SharePoint installation without any SP:s applied


Align and reshape polygons based on surrounding polylines

Question: I am trying to use a shapefile with polygons and I am trying to align it to a road network, that the polygons align themselves to surrounding streets. Is there a way to automatize alignments between nodes of the polygons and polylines or sometime similar?
Comment: Can you post a picture of a typical polygon/line situation please?
Comment: You have tags for QGIS and ArcMap but which would you prefer to use to try and do this?
Answer: In ArcGIS...
Let's say you have polygons and lines such as in the example below:

Perform a feature to line, with the polygons and the lines as your input. This slices the polygons by the lines.

Select all the features on one side of the line.

Export selected features.

Turn off all layers except the new layer.

Select the 'slivers'.

Perform an Eliminate.

Now do the same for the other side of the line and merge your results, along with any other polygons from your original polygon feature class that weren't included in the geoprocessing.


Eigenvalues of product matrix

Question: I have two matrices, both positive definite, real symmetric and one is diagonal. What can I say about lower and upper bound of the eigenvalues of the product matrix in terms the of lower and upper bounds on eigenvalues of those two matrices.
Answer: TravisJ already answered the question for the upper bound on the eigenvalues of the product of two symmetric positive definite matrices,
$$\lambda_\text{max}(AB) \le \lambda_\text{max}(A)\lambda_\text{max}(B).$$
To get a lower bound apply the upper bound inequality to the inverse*:
$$\lambda_\text{max}\left((AB)^{-1}\right) \le \lambda_\text{max}(A^{-1})\lambda_\text{max}(B^{-1}).$$
Since the eigenvalues of the inverse are the inverse of the eigenvalues, this is the same as,
$$\frac{1}{\lambda_\text{min}(AB)} \le \frac{1}{\lambda_\text{min}(A)}\frac{1}{\lambda_\text{min}(B)}.$$
Multiplying through to clear the denominators yields the nice minimum eigenvalue bound,
$$\lambda_\text{min}(A)\lambda_\text{min}(B) \le \lambda_\text{min}(AB).$$

*The inverses exist because the matrices are assumed to be positive definite in the question. The result extends to the case where the matrices are positive semi-definite as well. In this case, either $A$ or $B$, are not invertible, and the above proof would divide by zero. However, in this case either $A$, or $B$ has zero as the minimum eigenvalue, and $AB$ has zero as the minimum eigenvalue, so the inequality becomes $0 \le 0$.
Comment: @tranisstor Thanks for bringing up the issue of invertibility in your edit. The pseudoinverse is not required though, as the result holds directly as 0=0. I've done another edit to address this.
Answer: The largest eigenvalue of such a matrix (symmetric) is equal to the matrix norm.  Say your two matrices are $A$ and $B$.
$$\Vert AB\Vert \leq \Vert A\Vert \Vert B\Vert = \lambda_{1, A}\lambda_{1, B}$$
where $\lambda_{1,A}$ is the largest eigenvalue of $A$ and $\lambda_{1,B}$ is the largest eigenvalue of $B$.  So the largest eigenvalue of the product is upper-bounded by the product of the largest eigenvalues of the two matrices.  For a proof of what I just asserted, see: Norm of a symmetric matrix equals spectral radius
In terms of the smallest, it looks like the product of the smallest two eigenvalues also gives you a lower bound on the smallest eigenvalue of the product.  For a complete reference on how the eigenvalues are related, see: https://mathoverflow.net/questions/106191/eigenvalues-of-product-of-two-symmetric-matrices
Comment: I am sure this does not give any lower bound, on the contrary of what you said $\prec$ is not a component-wise comparison.
Comment: @timhortons, after more clearly reading "weak majorizing" it appears that you are correct... at least for the lower bound.  The majorizing means each sum of the first $k$ elements from the vector satisfy the inequality.  The upper-bound on the solution is certainly correct.  I will remove my erroneous comment.
Comment: If we have lower and upper bounds for the eigenvalues, then we have lower and upper bounds for the determinant of the product matrix. This combined with the upper bound on the largest eigenvalue of the product provides a lower bound on the smallest eigenvalue of the product matrix. DOne!
Comment: Shouldn't it be that $\lambda_{1,A}$ and $\lambda_{1,B}$ are the absolutely largest eigen values of $A$ and $B$ respectively?
Comment: @pikachuchameleon (late comment, left mostly for those seeing this now).  A positive definite matrix (as in OP) only has positive eigenvalues.  So the largest and absolutely largest eigenvalues are the same thing(s).
Answer: I think there is something wrong with the identity. For example consider L as lower triangular matrix of 1, i.e. Lower triangular entries are all 1 including diagonal and rest are zero. The clearly the eigenvalues of L are all 1. Similarly eigenvalues of transpose of L are all 1. However eigenvalues of product of $L^TL$ are dispersed widely, as the sum of diagonal of $L^TL$ is n(n+1)/2, where n is the dimension of matrix L.
Comment: The statement is about symmetric matrices.

Eigenvalues of product matrix


general equation of a tangent line to a hyperbola

Question: Suppose that there is a hyperbola of the form $\frac{x^2}{a^2}-\frac{y^2}{b^2} = 1$.
I would like to figure out an equation that describes tangent line to this hyperbola.
How would I be able to do this using calculus? My calculus trials are bring me some gibberish answers.
I did use the calculus below, but what I want is how to derive the general form equation of $y=mx \pm \sqrt{a^2m^2-b^2}$ where $m$ refers to the slope of a tangent line.
Answer: (1a)
Let $y=mx+c$ be a tangent of $$\frac{x^2}{a^2}-\frac{y^2}{b^2}=1$$
Let $(h,k)$ be the point of intersection.
So,  $k=mh+c, b^2h^2-a^2k^2=a^2b^2\implies b^2h^2-a^2(mh+c)^2=a^2b^2$
or,$h^2(b^2-a^2m^2)- 2a^2mch -a^2b^2-a^2c^2=0 $
This is a quadratic equation in $h,$  for tangency, the roots need to be same, to make the two points of intersection coincident.
$\implies (- 2a^2mc)^2=4\cdot (b^2-a^2m^2)(-a^2b^2-a^2c^2)  $
$a^2m^2c^2=a^2m^2b^2+a^2m^2c^2-b^4-b^2c^2$ cancelling out $a^2$ as $a\ne0$
$0=a^2m^2b^2-b^4-b^2c^2$
$0=a^2m^2-b^2-c^2$ cancelling out $b^2$ as $b\ne0$
$\implies c^2=a^2m^2-b^2\implies c=\pm\sqrt{a^2m^2-b^2}$

(1b)
Alternatively, we can take the central conic to be $Ax^2+By^2=1$
Applying the same method we get, $ABc^2=A+m^2B$
Here $A=\frac 1{a^2},B=-\frac 1{b^2}\implies  c^2=a^2m^2-b^2$

(2a)
Using calculus as André Nicolas has already done,
we find the equation of the tangent to be $$\frac {xx_1}{a^2}-\frac{yy_1}{b^2}-1=0$$
Comparing with $mx-y+c=0$ we get, $$\frac{x_1}{ma^2}=\frac{y_1}{b^2}=\frac{-1} c$$
Now $(x_1,y_1)$ lies on the given curve, so $\frac{x_1^2}{a^2}-\frac{y_1^2}{b^2}=1$, eliminating  $x_1,y_1$, we shall get the desired result.
(2b) we know , the parametric equation of the given curve is $x=a\sec t,y=b\tan t$
So, the equation of the tangent becomes $\frac{x\sec t}a-\frac{y\tan t}b-1=0$
Comparing with $mx-y+c=0$ we get, $$\frac{\sec t}{ma}=\frac{\tan t}b=\frac {-1}c$$
So, $\sec t=-\frac{ma}c,\tan t=-\frac b c$
Now use eliminate $t$.
Answer: It is such a nice equation that we might as well differentiate with respect to $x$ immediately. We get
$$\frac{2x}{a^2}-\frac{2yy'}{b^2}=0.$$
Solve for $y'$.
Remark: Alternately, we can solve for $y$ in terms of $x$. We get two equations. Then differentiate. A bit messier than the differentiation above, but doable.
The device we used, implicit differentiation, is very useful. In or situation, we can think of the differentiation of $y^2$ with respect to $x$ as using the Product Rule, or the Chain rule. Note that $y^2$ is a product. Its derivative with respect to $x$ is $yy'+y'y=2yy'$.


Creating "view" of "user blogs" specific to a user

Question: On a user "my account" page, I want to create a view block which lists the blogs created by that user only. Is there a way to accomplish this ?
Answer: There are solution for it by using Contextual Filter in views. Follow this -

Create a new content view and limit it to the content type you want.
Uncheck "Create a page" and check "Create a block." Select the format you want.Click "Continue & edit."
Add a contextual filter for "Content: Author uid.". Do this --

Under "When the filter value is not available," select "Provide a
default value," and select "User ID from URL" from the dropdown.
Because blocks don't understand contextual filters very well, the view
won't work properly without this default value, and all posts of the
given content type will show on all user pages (not just the user's
own posts).
Under "When the filter value is available or a default is provided,"
check "Specify validation criteria" and select "Basic validation" as
the validator. Select "Hide view" from the dropdown.

Save your view.
Assuming that you created a block display, the block will now be available on the Blocks page. Go there and open it.
Set your block to display on all user pages (/user/*) in the correct region. Save the block.
Your block should now appear on all user pages, showing the content written by each user.

Let me know the result if it works fine :)
Comment: It worked absolutely fine and to the requirement. I was doing the same thing but was stuck at the contextual filter part. Thanks a lot for your help. :)
Comment: @Nikhil Welcome :)


How (or when) do gluons change the color of a quark?

Question: I know a baryon is only stable when it contains a quark of each color. And as far as I know, the gluon essentially changes the color of a quark and moves onto the next, and this is what holds the particles together. But in the process of the gluon moving from one quark to the next, wouldn't the baryon have two quarks of the same color, making it unstable? Or does the gluon move instantaneously, or is the baryon not unstable enough to decay before the gluon reaches the next quark? Or... essentially, how does this process actually work?
Answer: The idea that baryons contain three quarks is a significant oversimplification wrong. It works for some purposes, but in this case it causes way more confusion than it's worth. So you should stop thinking of baryons as groups of three quarks and start thinking of them as excitations in quantum fields - and in particular, excitations in all the quantum fields at once. Quark fields, gluon fields, photon fields, and everything. These excitations propagate through spacetime and convert among each other as they go, and in a baryon, the propagation and mutual conversion happen to sustain each other so that the baryon can exist as a coherent particle for a while.
One of the conditions required of all these excitations in fields is that they be a color singlet, which is the strong interaction's version of being uncharged. There's a simple intuitive justification for this: just as an electrically charged particle will tend to attract oppositely charged particles to form neutral composites (like protons and electrons attracting each other to form atoms), something which has the charge associated with the strong interaction (color charge) will attract other color-charged particles to form neutral composites (color singlets).
Now, if you literally only had three quarks, the only way to make them a color singlet is to have one be red, one be green, and one be blue.1 (Or the anticolor equivalents.) But with all the complicated excitations that make up a baryon, there are all sorts of ways to make a color singlet. You could have three red quarks, a green-antired gluon, and a blue-antired gluon. Or two red quarks, two green quarks, an antiblue antiquark, a blue-antired gluon, and a blue-antigreen gluon. Or so on; the possibilities are literally infinite.
The point is that you don't actually have to have a quark of each color in the baryon at all times. Only the total color charge in the baryon matters.
Given that, it should seem reasonable that gluons change the color of quarks whenever they are emitted or absorbed, in a way that keeps the total color charge the same. For example, a blue quark could absorb a green-antiblue gluon and become a green quark.

1I'm glossing over some quantum-mechanical details here; specifically, a color singlet wavefunction needs to be an antisymmetrized linear combination, like $\frac{1}{\sqrt{6}}(rgb - rbg + gbr - grb + brg - bgr)$, not just $rgb$. But as long as you don't worry about which quark is which color, for purposes of this answer it's safe to ignore this.
Comment: @octonion Indeed I know this is an oversimplification, but IMO an appropriate one for the level of this question.
Comment: I'm sure you know this David Z, but this answer is an oversimplification of the way color works. There are eight color charges not three and we can't ignore quantum mechanical superpositions. If we have say a red up quark, a blue down quark, and a green strange quark, that is not a pure singlet. Part of it is charged. Similarly any particular color combination like red and antired is not a pure singlet and has a charged component.
Comment: +1 for "neutral composites" - great way of intuitively introducing colour singlets by analogy to electrical charge.
Comment: Reflection is really just absorption followed by emission. Gluons are constantly being absorbed and emitted, so I suppose you could say that in some cases they're reflected.
Comment: Makes sense, but does the gluon-bouncing idea still work? I assume that in order to change the quarks color (or even change the structure of the baryon) that would require a gluon, or something, to be absorbed in the process, just like in your example with the blue quark and the green-antiblue gluon. If so, wouldn't that make the gluon-bouncing idea infeasible, since the gluon would just be absorbed instead of "reflected" so to speak?
Answer: The model you are thinking about is really rudimentary and cannot explain the dynamics of Quantum ChromoDynamics, QCD .
In this link there is a better exposition of what a proton is, within QCD.

You may have heard that a proton is made from three quarks.  Indeed here are several pages that say so.  This is a lie — a white lie, but a big one.  In fact there are zillions of gluons, antiquarks, and quarks in a proton.   The standard shorthand, "the proton is made from two up quarks and one down quark", is really a statement that the proton has two more up quarks than up antiquarks, and one more down quark than down antiquarks.   To make the glib shorthand correct you need to add the phrase "plus zillions of gluons and zillions of quark-antiquark pairs."  Without this phrase, one's view of the proton is so simplistic that it is not possible to understand the LHC at all.

In the over all counting balance the proton is color neutral and it is the huge number of gluon exchanges that generate the potential that keeps the three valence quarks tied up as a proton. Because it is a quantum dynamic framework the mathematics is not simple and has to be approximated by lattice QCD .

But in the process of the gluon moving from one quark to the next, wouldn't the baryon have two quarks of the same color, making it unstable

The stability is ensured by the innumerable exchanges between all those constituents. Color transfer from one quark/antiquark is compensated by the color remaining behind, the overall remaining color neutral.

how does this process actually work

It is essentially a quantum mechanical process, could be imagined by a summation of an infinite number of Feynman diagrams of this type exchanging gluons

The over all colors do not change adding up to color neutral for the whole bag.
To be fair one should explain that there do exist distributions within the proton that show the existence of valence quarks and sea quarks and gluons in the parton distributions, but that is another story.

Figure 2: Overview of the CTEQ6M parton distribution at Q = 100 GeV

The enhancement on large x is the "proof" of valence up and down quarks.
Comment: The LHC site mentions that in the "sea of quarks" that makes up a proton, after accounting for all the quark-antiquark pairs, you end up with a the net result of the simplified 3-quark proton. Is this just an approximation that usually works, and if so why is it so precise, i.e. why not 0 net quarks or 6? And if it isn't an approximation, why is it so specific given the unimaginable number of quarks in there; what physical property makes this balance so exact?
Comment: @Vedvart1 Sea interactions conserve (quarks-antiquarks)/3, the "baryon number". In theory you could go up to 4 valence quarks + 1 valence antiquark, but that causes meson emission. (I'm simplifying 2 things by neglecting pentaquarks and baryon number conservation violation, both of which are rare, especially at low energies.)
Comment: @Verdvarti Further to anna v's explanation, in the Standard Model baryon number conservation violation can occur only non-perturbatively, but we think its true occurrence is higher based on the Sakharov conditions' explanation of nature's matter-antimatter asymmetry.
Comment: @J.G. Why do they conserve that number then? Is it just something we've found experimentally that we essentailly accept as an axiom of sorts? If there is something causing this, do we know what it is?
Comment: Yes , baryon number conservation, charge conservation are basic observational laws incorporated in the standard model of particle physics, with a number of more esoteric quantum number conservations. The model calculations incorporate all conservation laws.
Answer: A short answer that's useful when thinking of individual quarks works:
The gluon also has color.  There are 8 different forms, to go with the 3 colored quarks.
So if you start with a red and blue pair of quarks, the red changes to blue and you have two blue quarks and a gluon that's red and anti-blue.  Then the second quark absorbs it, cancels out the blue/anti-blue and is left with red itself.
Now the exchange between quarks is with virtual gluons, so don't worry about it knowing where it's going ahead of time.  It's the same issue you have in explaining how photons carry the momentum beween charged objects.
Comment: Could you explain exactly what virtual particles are? From what I've gathered, they're just particles from a process with one input and two outputs, regardless the cause.
Comment: No, I won't address what should be a new physics question in the comments.  But look: [it's already been asked here](https://physics.stackexchange.com/questions/286721/what-actually-are-virtual-particles).  Others are mentioned and linked from there.
Comment: Could it be explained like RQ + BQ >>> BQ + BQ + RABG >>> BQ + RQ? Being RQ = red quark, BQ = blue quark, RABG = red anti-blue gluon.
Comment: @EnderLook that looks right.


How do I separate .txt data into multiple columns when exporting to .CSV?

Question: I have .txt data that is described as Lat Lon Elevation (meters) and when I export to .CSV in Excel it puts all data into 1 column. So when I import the data into QGIS it all dumps into 1 column, and I cannot change the X and Y value column names when importing as Delimited Text File. Help!
Comment: QGIS on Mac OSX has some issues with incorrect line endings, so look out for that on this site if you encounter similar problems: http://gis.stackexchange.com/questions/137260/qgis-wont-read-table-columns-in-csv-import-on-mac-os
Comment: What delimiter is used in the text file? Maybe you're choosing the wrong type and as such your data is not recognized as column separated. Posting a data sample can be helpful to answer your question.
Answer: QGIS can import the .txt file as is, you don't have to convert it to a .csv and thus possibly corrupt the tabulation.
Ssing the add delimited text layer layer creation box, you can see that it recognizes .txt as one of the acceptable formats.
Answer: Assuming that the LAT-LONG-METER field has a consistent number of characters for each entry, you could use right() and (left) to pull apart the text street into new columns, name those what you pleased, and then import them.
Answer: You can also save as ".csv" directly from the notepad. Just open your text file (.txt) with Notepad (or Notepad++ or a similar software) and save the file as ".csv". You don't need to save it from Excel.
If you still want to save your txt as csv from Excel, after the creation of the csv open it with a text editor and verify which delimiter Excel has created. In case it is not a comma, when importing into QGIS use the custom delimiter and specify the type.


How does one determine if killing an evil creature is an evil act?

Question: I wanted to ask you in my D&D game, we fought some goblins. They attacked us first. We killed most of them; my character gave the rest a chance to surrender and said he may let them go. He questioned the goblins. I rolled an insight check, and my character perceived as if they enjoy attacking people a little determining that the greenskins were immoral. He then decided that to kill them would be safer, however, my friend who was a warrior cleric (very moral character class in the game) disagreed; we fought. My dungeon master said my character did an evil act. Is this true? How does one go about determining this? What are some lines of argument by common theories of ethics? His reasoning was that they were compelled by a bigger goblin and were not acting wholly of their own free will. I am not a philosopher, but I wanted more insight on how to conduct such an argument.
Comment: It makes a difference: we do not usually kill humans, but we kill everyday animals to eat them. Maybe the issue is: are goblins edibles ?
Comment: To kill goblins ?
Comment: Yes sorry if it's dumb.  I mean let's say it was humans instead of goblins?
Comment: Should this question go here: https://rpg.stackexchange.com/ given the specific morality of DnD might apply?
Comment: @tkruse, I think the distinction in a way is between whether we're asking "does the game say it's good" and "if we were in that world would it be good".  The former question should absolutely be migrated, but the latter is potentially independently philosophically interesting.
Comment: Edited to avoid the 'opinion' objection.
Comment: Oh, and you don't need to apologize for having the brains and imagination to engage in mathematically based interactive narration with grand philosophical overtones, IMNSHO. Good luck!
Comment: "'Good' and 'evil'
are purely human concepts. It would never occur to anyone to argue about
whether a fish, or a tree, were good or evil, because 'good' and 'evil' are concepts humans made up in order to compare ourselves with one another.
It follows that arguing about whether humans are fundamentally good or
evil makes about as much sense as arguing about whether humans are
fundamentally fat or thin." - Graeber & Wengrow. "Mankind has no essential nature."- Sartre. And similarly, goblins.
Comment: "The line separating good and evil passes not through states, nor between classes, nor between political parties either -- but right through every human heart -- and through all human hearts." - Solzhenitsyn. See: 'All evil is potential vitality in need of transformation' https://philosophy.stackexchange.com/questions/51482/all-evil-is-potential-vitality-in-need-of-transformation/51484#51484 And 'Evil/good understood as selfish/cooperative' https://philosophy.stackexchange.com/questions/77818/evil-good-understood-as-selfish-cooperative/77829#77829
Comment: The moral position of orcs & goblins in Tolkien is an active topic of discussion https://en.wikipedia.org/wiki/Orc#Debated_racism Those in the books serve a dark lord, & are night creature &/or live underground, so you could argue have only been corrupted, & suffer racism. I like this take, applying post-colonial political thought to the issues: https://existentialcomics.com/comic/175 There's also https://en.wikipedia.org/wiki/The_Last_Ringbearer which retells the Tolkien stories as racist colonial elves suppressing an industrial revolution
Answer: So.  Something important to understand about Dungeons and Dragons is that, unlike in our reality, Gods actually exist and have real and tangible consequences and agency in the world in which they live.
In our world, we have a problem for a theological model of morality which is called the Euthyphro dilemma.  Identifying Goodness with the will of the Gods introduces a problem, which is to ask whether the Gods do what they do because it is good, or whether what they do is good by definition because it is what they do.
In the Dungeons and Dragons multiverse, it's easy.  Alignment exists within a pantheon.  Some Gods are Good, and doing what they like is doing a good thing.  Some Gods are Evil, and doing what they like is an evil thing.  Good and evil are perceived in certain ways by creatures and people in that world and as such they align themselves to certain domains which are overseen by those Gods, deciding everything within their domain.
So, if you want to plead your case as being a Good action, you have to ask yourself - which God are you pleading to?
Comment: Considering the questioner's scenario as a thought experiment, both the question and this particular answer are well within the scope of philosophy.
Comment: Morality does not require a God.
Comment: Thanks for your answer. Sorry again
Comment: No need to apologise! It's an interesting question, though there are some specific aspects of DnD that maybe wouldn't be so relevant for us making a similar decision as humans.
Comment: @GuyInchbald, of course it doesn't.  However, the definitive, demonstrated and factive existence of one would inform morality. In DnD, this is the case, even though in the real world, it is not.
Comment: My understanding is that this is a philosophy forum, not an RPG forum.
Answer: Let's put the goblin aside and concentrate on humans. This raises genuine ethical issues.
What would an evil creature be? A being that is in some way intentionally extremely destructive of value. Behind this abstract formula I refer to a being that commits mass murders, that tortures children for amusement, that burns alive a lover who has jilted him, &c.
We need to add a condition such as that the being in question is not criminally insane but in a relevant sense knows the difference between right and wrong as evidenced by the fact that he acts on it in other contexts.
'Evil' is not a concept that has received close analysis in recent philosophy. The above is the best I can manage. My own view is that it is sufficient to prevent the evil being from continuing or repeating his extreme destruction of value. To go beyond this and to kill him is justifiable if and only if there is no practicable alternative in terminating his activities. We need only restrict his activities by compulsory confinement. The presumption is against killing him since it would be preferable to reform him, if this were possible, than to kill him. If we kill him we lose the (potential) value of a reformed life. If he does not reform, we are no worse off since we have prevented him from continuing or repeating his extreme destruction of value. We cause some harm to him in restricting his freedom but that is more than offset by the security gained for others from his extreme activities.
Comment: You do not seem to be distinguishing between evil beings and evil acts. We assume that "evil" acts are intentional and carried out by self-conscious beings with free will. We do not talk about "evil" tigers or "evil" flowers (Baudelaire aside). If there is free will then, there is usually some possibility of redemption (Dante aside). So I'm not sure that a resolutely, actively "evil being" is coherent. I believe Plato and Augustine had something like this in mind. An absolutely "evil being" is self-negating.  But, as you note, it is not a well-defined idea in philosophy.
Comment: This is a most valuable comment. I suppose I was thinking of evil beings as those whose actions are invariably or predominantly evil. I'd make the act/ agent connection in that way. But your comment should stand bringing the distinction into salience, and I thank you for it. Best - Geoffrey
Comment: @NelsonAlexander: I don't think it's accurate to say evil has not had close analysis & discussion in recent philosophy, or at least modern philosophy  https://plato.stanford.edu/entries/concept-evil/ even if the problem of evil & theogenies make it of particular concern for Christian apologetics
Answer: Both. It depends on who, what,when, where, how and the perception of the characters and Game master. Now I'm just a country Kobold lawyer but it seems like it would be an issue with procedural process combined with player inexperience hashing these things out at the tavern where the adventures always begin. Did the cleric have to roll a perception check? Did the cleric check what the gods position on preventing future harm? It's "Batman syndrome". Batman has decided that killing is the line at which he becomes evil. I have thought about this sooooooo much!! Ok here we go. Batman has a hand in the creation of nearly all of his enemies so he shares responsibility for future harm. Sometimes the situations don't give Batman the knowledge that the vat of acid didn't kill Jack Napier but merely elevated him to joker status. I.e. Level up. But many situations afforded an opportunity to end a spree of violence permanently which Batman refuses based on his arbitrary decision that killing is the line that cannot, must not be crossed. But the joker keeps escaping from Arkham asylum, going on a new spree of violence and murder and all the nasty things that make him so "evil" according to Batman and the general societal consensus that killing is bad Mmkay? But Batman actually takes full responsibility for every harm committed after Batman chose not to end it permanently. So NOT killing Joker is more evil, especially when it happens over and over and Batman refuses to end it, that responsibility is compounded exponentially until Batman becomes the most evil of all when multiplied by all the villains he won't kill times all the second and third chances he had to do so. If your character perceives that this won't be the end of mayhem and that somewhere some poor thing is going to be dragged into the warrens to an unimaginable fate, stopping that is most good. But to the cleric whose interpretation of their gods rules is more like the wild west where if all parties had guns and were shooting it's a fair fight if it started by choices those parties made based on masculinity or whatever, it was "Killing" not "Murder" and was therefore legal. But if in the case one guy shoots the gun out of the others hand and that person no longer has equal ability to fight, to kill this "unarmed" outlaw is murder. If it was a fight for dominance then they can both walk away if they both aren't liable for disturbing the peace or some such local law. If the disarmed is a bad guy here to pillage then he must be handed over to the Marshall. Your character sought to avoid "Batman syndrome" while your cleric companion sought to hand them over to the Marshall. Basically your Game master failed his perception check to realize the differing principles of the party. Because "Batman syndrome" is as far as I know,  a concept of my own intellect I can understand why and how this happened. P.S. I will relinquish claim if someone proves that the term was coined before 1996 when I came to the realization that Batman is a coward and narcissist of epic proportions,seeking only to play the game not win.
Answer: The situation of killing a goblin and deeming it evil is analogous to justifying killing predators such as lions, or other vicious predators (i.e. weasels) on the account of their 'evil' nature.  It used to be the case in history that animals were trialled and executed just like humans. This is clearly wrongheaded.
As in, can they be rational enough to willingly be 'evil', understand the concept of 'Evil', or accountability of their actions? Or do they follow their instincts which they cannot reasonably control?
Daniel Dennett, for example, argues that control is a very important factor in assessing accountability:

A key word in understanding our differences is "control."
(...)
"the way we are is ultimately the result of factors beyond our
control" and that is true of only those unfortunates who have not been
able to become autonomous agents during their childhood upbringing.
There really are people, with mental disabilities, who are not able to
control themselves, but normal people can manage under all but the
most extreme circumstances, and this difference is both morally
important and obvious, once you divorce the idea of control from the
idea of causation.[1]

This relates to instincts, and their suppression, in the animal world. Morality, which is just that kind of suppression/control, is not a given by virtue of lifeform merely existing. Otherwise, you would see vegetarian crocodiles, or bonobos setting up charities.
It is preposterous to think that. Just imagine an example:

A hunter. A hunter can choose to either hunt the animal or go to the supermarket and buy yoghurt in order to survive. A hunter understands the alternative and has the power to act for specific moral considerations.
A lion. A lion has to hunt the animal in order to survive. A lion cannot know or comprehend the alternative, therefore, it is necessitated to do so; it cannot choose otherwise.

Therefore, the former acts morally, but not the latter. The latter cannot be consciously 'evil'.
Coming back to goblins being 'evil', you could also make the same argument against Pygmy people or other modern hunter-gatherer tribal people. Those would want to kill you for the same reasons as goblins would, since their level of social organisation is akin to goblin tribalism. Are then tribal people 'evil' because of what they currently are?
1. Dennett, Daniel; Caruso, Gregg. 'Just Deserts' (p. 19). Wiley.
Comment: Pygmy just means diminutive, & it comes with colonial baggage. It's most strongly associated with peoples of the  Congo, but also peoples in Myanmar & Australo-Milenesia. Making specific associations is problematic at best. 'Tribal people' the same, with Wampanoag peoples having been critical to the first North American colony that survived winter , & a 1st people tribe to Alexander Mackenzie surviving the first crossing of Canada. So, as concrete example: the people of North Sentinel Island who have determined that all intruders should be killed (probably after numerous bad experiences).


What is the Concept of catalog and catalog aware items in hybris?

Question: I have gone through all the formal definitions of these terms. But still, i have tough luck understanding them. I am a beginner in hybris. So Can somebody explain these concepts as simple as possible?
Answer: You must first understand the catalog concept in hybris.
The catalog in hybris, or anywhere in the world contains items for business. Therefore, Catalog in general, is the container of the commodities which are sellable entities (product) and which can be referred by the end users for transactions.

The catalog is not limited to just list of items, but how they are arranged also. Just an example, if you go to food restaurants, you can refer to their menu (that is actually a generalized catalog). You would notice that different restaurants, though serve the same food, but have different arrangement of items (products) in their menu - sometimes with different names, sometimes under different sections (categories). This is very similar to the hybris product catalog.
Now, taking the restaurant example further, Again two restaurants might serve the same food, but will have different ambience. This means the theme of the restaurant, the uniform of the waiters, the logos etc. This is similar to the hybris content catalog
Therefore, summarizing the above explanations, hybris has two catalogs - Product Catalog responsible for arrangement of the product hierarchy and the other as Content Catalog responsible for the layout (or the e-ambience)  of the website.

Hybris Catalog has two versions - Offline (Staged) and Online. The business users work on the Staged version and push it (to) Online once the item under work (product or content) is suitable to go live. They do this via a process called Synchronization.
This process picks the items from Staged version, checks for some rules (which indicate that the item is ready to go live), and creates (or updates if already created) a copy of the item with Online as the version. Hybris system understands that only Online needs to go live, picks the item, and displays it on the website (storefront).

Now, there are some entities which should have two copies in the system, so that Business users (like content managers or product managers) can make appropriate changes to make it look suitable on the website before it actually appears there. E.g. - Product, Images etc.
But there are certain items which need not to have to copies of them, E.g. - Price, Stock etc. because they would be same for both copies of the item (Product in this case) and creating another copy would be an overhead on the system.
Therefore, the items that (should) take part in the synchronization process like Product, CMS Pages, Components etc. are called Catalog Aware.
The items which do (or should) not take part in synchronization process are called Catalog Unaware
Hope this helps!
Comment: Can you tell me about product catalog and content catalog?
Comment: @Vikrant very nice basic understanding.
Answer: In hybris one catalog can have different catalog versions. Product catalog has mainly 2 catalog versions — Staged and Online.
Staged Catalog — this catalog version is a test catalog version. Modifications are made first in the staged catalog. When changes/modifications are tested/approved and you are satisfied then you publish them to be available online to your users by synchronizing staged catalog to the online catalog.
Online Catalog — this catalog version is is the one which will be used to display on the storefront(the active one).


Win Server 2008 Hanging on "Applying Computer Settings"

Question: Applied ~8 updates this morning, and on reboot the server just sits on "Applying Computer Settings". I've let it sit for a max of almost 40m with no response. I hard-booted (/duck) and can get into safe-mode. From there it applies it's updates and is ok. But still on normal boot gets stuck in "applying". I've tried uninstalling the updates from safe-mode with the same reaction. Any insights?
Answer: Does this server happen to run IIS?
http://support.microsoft.com/kb/2004121
Since you can get into safe mode, do you see any errors in the event logs correlating to the time frames of when you were booting normally? Have you tried booting with the network cable unplugged?
Errors at this stage are typically group policy related, although the coincidence of new updates is not lost on me. The following article is old, but still relevant for troubleshooting.
http://support.microsoft.com/kb/250842
Comment: Sorry for the late accept. You are right, it ended up being an issue with the domain controller.
Answer: Is this a domain machine? In many cases, Windows will hang for an unreasonable amount of time during the bootup process trying to locate a domain controller if DNS is unresponsive. If you're an AD member, double-check that your networking is configured correctly and is responsive, that DNS servers are configured correctly, that all servers are reachable, and that all of your AD SRV records are resolving correctly from the system.


Rusty brown spots on the leaves of chili plants — what could be the reason?

Question: I've already had this problem last year but still have no idea what causes these ugly rusty spots on my chilies' leaves :/ Do you have any suggestions?
Comment: If it gets worse, does it look like this? https://gardening.stackexchange.com/questions/8712/repotting-diseased-chilli-plants-possibly-rust
Comment: In the first image, the largest leaf seems to have tiny black specks or deposits along the main vein of the leaf - please inspect with a magnifying glass,  I can't tell what they are. Please also check beneath the leaves to see if there's  anything there that
 shouldn't be there.
Answer: My guess is it's a fungal disease, possibly alternaria. I've seen similar things on indoor peppers (as well as other solanaceae plants) with mites. I don't see particular signs of mites, however. Maybe I've seen it on strawberries I started indoors, too.
The main recommendation that comes to mind is to disinfect the area before you plant next year, and the pots, too. Use new soil. Never bring outdoor soil indoors. It can spread diseases and pests that can be hard to eliminate.
Also, mixing a bit of food grade diatomaceous earth with your soil, to keep pests out of it, might help prevent pests from living there and passing on disease, too (if that's the problem). Actually, you could spray water with diatomaceous earth in it on the growing area, and let it dry, to make it more pest-resistant. Any pests that walked on it might eventually die. It wouldn't stop flying pests much, though.
Parasitic algae might cause issues like that. I would avoid clear containers there, to prevent algae from growing, since it grows more with light. Your containers aren't clear; so, I wouldn't think it's the issue.


Do Legendaries only drop once in Borderlands 2?

Question: If I kill Savage Lee and get Unkempt Harold, am I able to get that gun again at a later level by grinding him again, or will it only drop once?
Answer: Savage Lee will spawn every time you load up Three Horns Divide (after you complete and turn in the quest The Road to Sanctuary).
This occurs whether or not he previously dropped an Unkempt Harold, so you can farm him as much as you'd like. This is commonly how players get Harolds with desirable parts such as the double-penetrating prefix and the Torgue grip.
Answer: Legendaries in general will drop by the cartload, if you replay the locations or quests where they have an increased drop rate. Sometimes they'll drop more often than you expect, and they'll drop so often that you're selling them off. This is how people deliberately acquire Bees, Norfleets, and other highly popular oranges. And how I acquire massive numbers of unpopular oranges, such as Skullmashers or Whiskey Tango Foxtrots. :-P


Vertex operators in string theory

Question: It is well known that operators in string theory are inserted at the origin. So, for example, the vertex operator for tachyon looks like
$$:e^{ik.X(0, 0)}:$$ However, while computing the string amplitude we use an integrated version of the vertex operator i.e. $$\int d^{2}\sigma \sqrt{det(g)} e^{ik.X}$$ This seems like a contradiction to me. Please explain why are these two equivalent ?
Comment: I think you mean $\sqrt{g}$ and not $\sqrt{\sigma}$ and that should help you find the answer...
Answer: Under the state-operator mapping we have the following identification  $$   |k;0,0    \rangle \longleftrightarrow   :e^{ik.X(0, 0)}:$$ where $:e^{ik.X(0, 0)}:$ is the normally ordered closed string tachyon vertex operator and $   |k;0,0    \rangle $ is the closed string tachyon ground state.
Now, why is $:e^{ik.X(0, 0)}:$ not used in computing string S-matrix elements?
The answer is that any S-matrix element must be invariant under Weyl and diffeormphism transformations, something like $$S(k)= \sum_{compact \\ topologies} \int \frac{[dXdg]}{V_{diff \times Weyl}} exp(-S_{x}-\lambda\chi):e^{ik.X(0, 0)}: $$
 can't work for obvious reasons, namely that $S(k)$ is not a scalar under diff and Weyl symmetries because $:e^{ik.X(0, 0)}:$ is an operator of conformal dimensions $(\Delta=\frac{l_{S}^{2}k^{2}}{4} , \Delta=\frac{l_{S}^{2}k^{2}}{4})$.
The solution is to integrate $:e^{ik.X(0, 0)}:$ over the relevant worldsheet as
$$\int d^{2}{\sigma} \sqrt{g} :e^{ikX}:.$$ Now is easy to see why this is the correct guess.
In locally flat coordinates we have the replacement $$\int d^{2}{\sigma} \sqrt{g} e^{ikX} \rightarrow \int d^{2}{z}  e^{ikX}$$ where we can turn $d^{2}{z}:e^{ikX}:$ into a tensor of type $(0,0)$ by noticing that $d^{2}{z}$ is of type $(1,1)$ and choosing $k^{2}=-m^{2}=\frac{4}{l_{S}}$.
Sleeping beauty: Please notice how beautiful is the fact that the precise value of the mass of the tachyon is enforced by consistency.
We conclude that the correct expression for a stringy S-matrix element should be $$S(k)= \sum_{compact \\ topologies} \int \frac{[dXdg]}{V_{diff \times Weyl}} exp(-S_{x}-\lambda\chi)\prod_{a=1}^{n} \int d^{2}{\sigma} \sqrt{g} :e^{ik_{a}X_{a}}: $$ As desired.
Comment: See section 2.5 and 2.5.2 for a complete understanding. He talks of two kinds of vertex operators integrated and non-integrated and shows their equivalence.
Comment: Thanks :) I'm not too familiar with the theory of super Riemann surfaces, but now I see I should. Although the logic seems (at least to me) much more elaborated, I completely agree, the Witten's derivation is clear and much more powerful.
Comment: Actually you can get the integrated form naturally without having to guess if you use a ghost fields and ghost action as well. This is explained in witten's paper perturbative string theory revisited.
Comment: Well, my humble opinion is the argument is not exactly a guess. The only way to "cancel" the conformal dimension of the tachyon operator is to contract it with a tensor of type (1,1) and locally there is no other choice than $d^{2}z$.  Anyway, if you have found a more satisfactory explanation, is ok.
Comment: Indeed, the argument interest me. Could you please point out the page in Witten's paper where the argument is elaborated?

Vertex operators in string theory


Chemical formula of Lactic acid

Question: Formula of Lactic acid is given as C3H6O3, can't this be divided by the common factor3, and written as CH2O?
Comment: FWIW, CH2O is the correct "empirical formula" for lactic acid, as you would calculate from elemental analysis.
Comment: This was supposed to be a _molecular_ formula. You don't divide molecules.
Comment: Basically, you can simplify or "divide" a molecular formula only if it really makes sense.
Comment: Basically, a given molecule has a unique (molecular) formula. However, some molecules have a tendency to associate to form bigger molecules. Only in that case can you simplify or "divide" a molecular formula. For example, elemental sulfur (S) is usually found in nature as S8 and then you can consider its true formula is S. Also P4S10 is a dimer of P2O5; you have P4S10 in your flask but you can consider P2O5 in your calculations.
Answer: You have initially tagged your question "structural formula", however $\ce{C3H6O3}$ is somewhat ambigous in this respect, and besides lactic acid can represent its isomer 3-hydroxypropionic acid, methoxyacetic acid, and almost completely different compounds like dihydroxyacetone, dimethyl carbonate, glyceraldehyde or trioxanes, not speaking of the second one $\ce{CH2O}$ (formaldehyde or ethylene oxide). Well, these are not structural formulas at all.

Chemical formula of Lactic acid


How does user's emotion relate to ux?

Question: I have been hearing a lot of emotional design and doing ux with user's emotion in mind. But how does this work and where does it fall under in the deliverables?
Comment: also, i see a lot of articles about emotional design. But their examples usually have to do with branding and UI. Not ux.
Answer: The experience map is everything
IME, a big piece of evaluating emotion happens during the experience mapping stage. You evaluate the users actions and state of mind at different points in their interaction with an organization, environment, or product.
It's less of a "deliverable" than it is something to reference (and update) continuously throughout the development and optimization of a product or service. Everything you develop should be considered in it's position on this map.
Connect your feature to the map
It's intuitive for most experienced designers, but this is a formal way of designing the solution in the context of the user's needs. It goes beyond designing features for personas, extending it with the persona's context. And context should always include an emotional component.

Is the user in a positive or negative state?
What other things are on their mind?
How can your new x improve that state?
Answer: Emotional Design is nothing new, just a relatively hip thing to name something that has been being done for decades.
Depending on the area of development, emotional design applies to different UX aspects. For example, in web/digital design, it is mostly an UI concept, while in physical products the relations vary, including shape, sound, light, texture and so on. Thus, it's easy to see the deliverables will be different and the moment of the UX process when emotional design concepts are applied will vary as well.
For the more modern approach to emotional design, and in a certain way the more accepted voice about emotional design in UX you can watch this TED talk by Don Norman. It's more focused to physical (it's 13 years old) but its three emotional cues

visceral
behavioral
reflective

still apply in modern digital media
Comment: Don Norman wrote a book called 'Emotional Design' (2004)
Comment: yes I know, I have it at 2 feet from what I'm now ;) Just wanted to provide something short, easy to understand and quite funny instead of "go read the book"

How does user's emotion relate to ux?


Calibre Hangs on Xubuntu and Cinnamon, but not Ubuntu or XFCE

Question: This is a really strange problem that has just started.  It appears to happen to other python apps as well?  At the risk of misleading, I think it might have to do with moving my user files?
Firs, a bit of background.  I am dual booting Windows 10 and Ubuntu 16.04.  I have my user files for both OS's(Documents, Downloads, Pictures, etc.) on a shared ntfs partition.  I am mounting the shared partition in fstab with:

UUID=xxxxxxxxxx   /media/SHARED/      ntfs-3g defaults,auto,exec,uid=1000,gid=1000,umask=002 0 0

All was working fine, until somehow my Windows install got corrupted and it started putting user info in the wrong place, my only choice was a repair install to windows where I moved my user files from (S: is the SHARED partition) S:/chad to S:/Users/chad.
My first thought was a permissions issue, but I THINK I have that all sorted.
If I start Calibre on Ubuntu (Unity) it starts right up, but on  Cinnamon and Xubuntu sessions it will hang with very high hard drive usage at "Initializing user interface..".
The reason I think it might be related to moving my user files:  I had a similar issue with Dropbox.  If I changed the dropbox folder location in the dropbox app, Xubuntu would hang on opening the file browser with the same hard drive churning.  If I tried the same on Ubuntu, no problems.
I have tried uninstalling xubuntu, xfce and reinstalling, still same problem.  If I use the XFCE session things again work fine.
Where do I start to track down the error?
I tried to run calibre from the command line with debug option calibre-debug --gui.  The system completely hangs, and this is the error that keeps repeating:

Gtk-CRITICAL **: IA__gtk_widget_style_get: assertion 'GTK_IS_WIDGET (widget)' failed
Answer: Okay,  I found an answer (workaround?) to my calibre problem.
From the Mobileread forums:
In terminal I entered:
calibre-debug -c "from calibre.gui2 import gprefs; gprefs['ui_style'] = 'calibre'"

That solved my problem.  I don't know what theme I had selected instead.  Maybe 'system'?


Why can some oscillations be modeled by Simple Harmonic Motion, while others cannot?

Question: For some oscillators an increase in the driving amplitude changes the period (frequency) of the oscillation, but the simple harmonic oscillator does not predict this type of behavior. Why?
Comment: At increased amplitude higher-order terms in the potential (quartic, etc.) become non-negligible.
Comment: Well, that would depend on the higher order terms now, wouldn't it?
Comment: Related: [Why is the harmonic oscillator so important?](http://physics.stackexchange.com/q/159021/44126)
Comment: Imagine a pendulum.  A pendulum is _not_ a simple harmonic oscillator.  I'm not a physicist, and I don't know what equation would accurately describe the motion of a pendulum, but whatever it is, it's going to have some terms that become more significant as amplitude increases, and it's going to have some that don't, and just by an amazing coincidence, the limit as amplitude approaches zero is going to look like an SHO.  Same goes for a mass and spring system where the spring does not actually obey Hooke's Law, but rather, some law that approaches Hooke's Law as displacement approaches zero.
Comment: That doesn't really answer my question.
Comment: Awesome, and how do those terms affect the period?
Comment: Fair enough, but are there any general examples of when the terms would shorten the period or lengthen it? Or a way to directly link period and amplitude?
Comment: see [Nonlinear spring $F=-kx^3$](https://physics.stackexchange.com/q/331632)
Answer: In general it's nonlinearity that leads to the type of behavior you describe.
Simple harmonic motion is usually modeled in terms of linear differential equations, but real physical systems tend to be nonlinear to some degree and sometimes the non-linearities can become large as a function of the amount of energy you put into the system.
As physicists or engineers we tend to force the nonlinear behavior into simple non-linear differential equations like the Vander-Waals model, the duffing oscillator, but more often than not there is the saturation nonlinearity (systems can only hold so much energy before they literally break)
For linear systems if you excite the system with a pure frequency you expect to see the same frequency at the system output. If you double the amplitude you would expect to see a doubling of the output. But if you excite a system and see changes in frequency with changes in the amplitude of your excitation, or non-proportional changes in the amplitude, then the likelihood is there is a nonlinear behavior lurking within.
Answer: Consider the example of a plane pendulum with bob mass $m$ and length $\ell$, where the potential energy of the pendulum bob is
$$
U = -mg\ell \cos\theta
$$
up to a constant.  For small angles $\theta\ll 1\rm\,radian$ this is approximately simple harmonic, because neglecting higher-order terms in the Taylor expansion
$$
\cos\theta = 1 - \frac{\theta^2}{2!} + \frac{\theta^4}{4!} - \cdots
$$
gives a potential proportional to $\theta^2$, just like a spring.  However the full equation of motion for a plane pendulum,
$$
m\ell\ddot\theta = -mg\sin\theta
$$
is a differential version of a transcendental equation.  The exact solution seems to involve the Jacobian elliptic functions.
There are an infinite number of ways an oscillator can be non-harmonic, so there isn't a general answer to your question as stated.


Can I place a soursop plant in the ground in a 20 gallon (91 liter) pot?

Question: Can I bury a soursop plant in the ground in a 20 gallon (91 liter) pot? I don't want it to grow to a 15 to 20 feet height tree because it would be too tall in the back yard.
Comment: Are you lacking the ground area to plant this tree in your back yard or do you just prefer for it to remain in a miniature state?  You could just plant it and then prune it back regularly to the size you prefer.  Any plant can be pruned to a preferred size, that is how the practice of Bonsai came about.
Answer: Well you could, but the only way it would grow healthily after a year or so is if it put roots out through the bottom of the pot into the ground, which it is very likely to do. The roots will come out through the holes in the pot and eventually break the pot as they increase in size. You can't stop the holes up because then there'd be no drainage for the roots. So on balance, my answer would be no, its not a great idea. If you are you growing it for its fruit, which it usually produces 3-5 years after its been planted in the ground, this might indicate it needs to be a certain size before it fruits, and it may not attain that size in a pot, even a 20 gallon one.
Answer: My soursop has been in a pot for 3.5 years since seed, 40L in size, will be repotting it shortly as its now 7foot tall, it's fruited once and has been pruned once decently.
These trees have a shallow root base so if you can provide for that and have a stable base, you just need to  make a healthy growing environment and it will do well for a while, long enough for you to explore options at your leisure for the future.


願いは叶う or 願いが叶います?

Question: Reading a raw manga and 願いは叶う was the chapter name which I think is "Wishes Come True" however after checking online "Wishes Come True" is apparently 願いが叶います, there is 2 differences, one being は and が the other is 叶う and 叶います, please explain what these differences are and which phrase i should use.
Comment: Google translate is not really a good way to go about "checking online."
Comment: The difference between は and が is  hard to understand for Japanese learners. Please check it. http://japanese.stackexchange.com/search?q=%E3%81%AF%E3%80%80%E3%81%8C%E3%80%80
Answer: Both は and が are particles of subject words, and those meanings are almost the same.
Though が is more emphatic than は.
For example, が is used in interrogative sentences for subject words usually.

"Who ate cookies?"
   「誰がクッキーを食べましたか?」
  "I ate cookies."
   「私がクッキーを食べました。」

In the case of interrogative sentences for object words:

"What did you eat yesterday?"
   「あなたは昨日何を食べましたか?」
  "I ate cookies."
   「私はクッキーを食べました。」

Those two conversations are not replaceable.
There is a detail of that in this site.
http://www.japanese-language.aiyori.org/article1.html

Incidentally, が is used as follows.

"the cookies I ate"
   「私が食べたクッキー」

が had a meaning of の in ancient Japanese.
の is a particle for the possessive case.

"my cookies"
   「私のクッキー」

Because "the thing I do" has a meaning of "mine", が is used in this case.
Answer: Difference between 願いは叶う and 願いが叶う is that the former is an answer to "How will my wish be?" and the latter is that to "What will happen then?".
Answer: 叶う is called the "simple" or "dictionary" form of 叶います. 叶う to me is the "true" or "original" form (grammatically), while 叶います is the polite derivation. Online translators will often give translations in polite form (~ます、~です) because they want to avoid learners being impolite. The rule of thumb for this (and Japanese classes in general) is that you can never go wrong or offend anybody with polite form. You could with the simple form, if you aren't careful.
Well then, I hear you say, why can't the chapter title use polite language?
Polite language implies that real humans are talking, and that there is some sort of human-to-human relationship structure. No one is "saying" your manga chapter per se, so there is no need to be formal. For the same reason, novels and newspapers are always written in simple form.
Examples:

叶う→叶います (to come true)
[書]{か}く→[書]{か}きます (to write)
[殺]{ころ}す→[殺]{ころ}します (to kill)
[立]{た}つ→[立]{た}ちます (to stand)
[死]{し}ぬ→[死]{し}にます (to die)
[読]{よ}む→[読]{よ}みます (to read)
[走]{はし}る→[走]{はし}ります (to run)
だ→です (to be)

Notice a pattern?
Comment: Yes I understand this! thank you very much
Comment: I thought the question was more about the difference between はand が.
Comment: I will edit the question
Comment: It was on both differences sorry if i did not make that clear
Comment: You could, potentially, offend someone with polite language, but if you could you were probably on casual terms with them to begin with.

願いは叶う or 願いが叶います?


I appear to have 'serial voted'. Would a moderator please explain the specifics so I can avoid doing it in the future?

Question: When I logged on this AM, I found that I had been deduced 12 reputation points because "Serial Voting was Reversed". Would someone please explain what I did that triggered the deduction, so that I can avoid making the same mistake again?
Answer: You most likely didn't do anything to trigger it directly, though you have led to it indirectly.
By raising a flag earlier to notify moderators about a case of serial downvoting, I ended up escalating the issue to try and have reputations restored to normality, which itself led to a chain of events that eventually culminated in a point recount made by the system.
From then on what the system does is really a black box to us, it may lead to favorable or unfavorable results to an undetermined number of users.
If you report a rep loss, then I presume among other things the system considered you were perhaps being favored by some other user, which may intentionally or unintentionally have upvoted an abnormal amount of your posts.
Comment: I see. It's weird that I lost 12 reputation and that I never did get any reputation back from the case where I was the victim of extensive revenge voting, but such are the vagaries of complex systems.  Thanks for the explanation.