Why only orientation-preserving transformations are considered when integrating forms?

Question: The volume form is known to be invariant under a change of coordinates $T$ with $\det(T)>0$, so consequently integral of forms are also invariant. But what happens when the change of coordinates has $\det(T)<0$? Is the integral invariant under transformations with negative determinant? In Calculus of one variable, when the determinant is negative one would just reverse the limit of integration, why we don't do the same when dealing with forms? In Calculus of multivariable, the absolute value of the determinant is taken, so I guess my question is related to why there's an absolute value there (is it put by hand or does it show up naturally?).
Comment: Whether or not you use the absolute value of the Jacobian depends on what you're computing. For some integrals, orientation matters, for others it doesn't. In the language of differential forms, you need to know whether you're integrating a form (such as $f\,dx\wedge dy$) or a density ($f\,dx\,dy$), which transform differently.
Comment: As I understand, the definition of an integral of a form as an integral of a density is only meaningful when det(T)>0, since that's when the volume form is invariant. But it seems to me that the outcome of the integral is always the same either way (for det(T)>0 or det(T)<0). So why not take this fact into account? I mean, why not say that det(T)<0 transformations are fine as long as one also reverse the limit of integration? In symbols this would mean

$
\int_Df\omega = \int_{T(D)} T^*f\omega
$

for any T.
Comment: $|J(T)|$ is in general not constant throughout the region. Showing that the Riemann sum converges when $|J(T)|\lt0$ in some subregions and $\gt0$ in others becomes difficult, if not impossible. If $T$ is orientation reversing throughout, then one could certainly do what you propose. BTW, the basic pullback identity is $\int_DT^*\omega=\int_{T(D)}\omega$, which is a bit different from what you've got.
Comment: I see, this answers my question, thanks. Just out of curiosity, is it possible to prove that $|J(T)|$ is constant in the whole domain in the Euclidean space, for any $T$?
Comment: Well, $|J(T)|=\text{const}$ means that $T$ multiplies volumes by the constant factor $|J(T)|$. That's certainly true of affine transformations, and I'm sure there are others for which $J(T)$ itself isn't constant, but it's not true for even the common polar-to-Cartesian transformation, which has $|J(T)|=\rho$. Another useful transformation is the parabolic coordinates $x=uv$, $y=\frac12(u^2-v^2)$, for which $|J(T)|=u^2+v^2$. The transformation is certainly orientation-preserving, but the Jacobian determinant isn't constant for this one, either.
Comment: Sorry, I meant that |J| doesnt change sign. For both polar-to-cartesian and parabolic transformations the sign of |J| doesnt change. So rephrasing my question, is it possible to prove that |J| doesnt change its sign, for any T, in the Euclidean space?
Comment: It's an idea worth exploring. I suspect that the answer will have more to do with the nature of $T$ itself and not the geometry of the space (after all, isn't everything locally Euclidean? ;))
Answer: $\newcommand{\di}{\mathrm{d}}
\newcommand{\de}{\partial}$
All kinds of coordinate transformations can be considered when integrating forms. The integral of an $n$-form over an $n$-dimensional submanifold is independent of any coordinates, so it's "invariant" no matter which coordinates we use and no matter their orientation. See below.
Sometimes people prefer to use only coordinates with the same orientation in order not to think about absolute values of determinants. Such absolute values appear in the coordinate transformation of a particular kind of forms. Typically, "volume form" are of that kind.
To understand this it's important to distinguish between integration over inner-oriented submanifolds and outer-oriented submanifolds.
Here's an example of inner-oriented 2D submanifold:

and of outer-oriented 2D submanifold in 3D space:

The first has a circulation sense on it; the second a flux direction through it.
Here's an example of inner-oriented 3D submanifold:

and of outer-oriented 3D submanifold in 3D space:

The first has a screw-sense; the second just a global "$+$" or "$-$" sign.
(Pictures adapted from Schouten [1989], see refs below.)
Non-orientable manifolds such as the Möbius
strip are actually
non-inner-orientable, but they are outer-orientable in 2D: we can just give
them the sign "$+$" everywhere. Any manifold is outer-orientable when considered as a submanifold of itself.
Many integrals typically considered in the sciences do not require an inner orientation (a screw-sense in the example above), but an outer orientation. For example, if we calculate the total mass in a region of space from the mass density given there, we don't care about any screw-senses in that region.
In the case of the Möbius strip, for example, imagine that a 2D mass density is defined on it – some parts have more mass, some have less mass. It's clear that we can ask what the total mass of the strip is, and we must be able to calculate it by integrating the mass density all over the strip. But wasn't the strip non-orientable? how is such an integral possible, then? It's possible because we're considering it as an outer-oriented manifold, and as such it has a well-defined "$+$" orientation. And we integrate an inner-oriented 2-form over it – the mass density – to get its total mass.

Before saying something more on the two kinds of integration, it's useful to remember: outer-oriented forms are integrated over inner-oriented submanifolds; inner-oriented forms are integrated over outer-oriented submanifolds. There's a sort of complementarity between the two. (I'm sure I'm going to mess up the two terms below, sorry in that case.)
Integration of outer-oriented forms over inner-oriented submanifolds
An outer-oriented $n$-form $\omega$ on an $n$-dimensional manifold in a coordinate system $(x_i)$ has just one component $\omega_{1\dotso n}$, and it's represented in that coordinate system by
$$\omega(x_i) = \omega_{1\dotso n}(x_i) \;\di x_1 \land \dotsb \land \di x_n \;.$$
This is the standard kind of form discussed in most differential-geometry textbooks. It's also called an "even" form.
Its outer orientation at a point is the same as that determined by the coordinates if $\omega_{1\dotso n}>0$, and opposite otherwise.
Under a change of coordinates to $(x'_i)$ its new component is given by
$$\omega'_{1\dotso n} =
\omega_{1\dotso n}\; \det\tfrac{\de x_i}{\de x'_j}$$
without any absolute values for the determinant.  From this formula it's clear that the outer orientation of $\omega$ at a point doesn't
depend on the coordinate system. If we change to coordinates $(x'_{i})$ with orientation opposite to $(x_{i})$, we'll have $\det\tfrac{\de x_i}{\de
x'_j}<0$, and this determinant in the above formula will automatically
flip the sign of $\omega'_{1\dotso n}$, so that the outer orientation of $\omega$ is the same.
An inner-oriented $n$D submanifold $C$ is represented as a map $F$ from a subset $U \subset \mathbf{R}^n$ to our manifold, such that $F(U)=C$.
This map also defines the inner orientation of $C$: it's the orientation
determined by the coordinates $(u_i)$ as mapped onto $C$.
In other words, it's the inner orientation of $U$ mapped onto $C$.
In the coordinate system $(x_{i})$ the map $F$ is represented by the functions
$$ x_{i} = F_{i}(u_{1}, \dotsc, u_{n})\;.$$
In these coordinates, where $\omega$ has component $\omega_{1\dotso n}$,
the integral of $\omega$ over $C$ is given by
$$
\int_C\omega \equiv
\int_U \omega_{1\dotso n}[F_i(u_j)]\;
\det\tfrac{\de F_i}{\de u_j} \;
\di u_1 \dotsm \di u_n \;.
$$
Note that no absolute value is taken for the determinant.
In fact the sign of the determinant in the expression above automatically
takes care of the orientation of $C$.
If in the integral above we had taken the absolute value, the integral
would have been for the domain with orientation induced not by the map
$F\colon U \to C$, but by the coordinates $(x_{i})$ -- an orientation we
don't care about. If the two orientations coincided, that is if
$\det\tfrac{\de F_i}{\de u_j}>0$, there'd be no problem. But if the two were
opposite, $\det\tfrac{\de F_i}{\de u_j}<0$, we would need to put
a minus sign in front of the integral if the determinant were taken in absolute value.
Integration of inner-oriented forms over outer-oriented submanifolds
Inner-oriented forms are also called "odd" or "twisted" (see refs below), and they are related to tensor densities. Note that "volume elements" are typically inner-oriented forms, not standard, outer-oriented ones as those described above; see Marsden & Ratiu [2007] and de Rham [1984].
An inner-oriented $n$-form $\omega$ on an $n$-dimensional manifold in a coordinate system $(x_i)$ has just one component $\omega_{1\dotso n}$, and it's represented in that coordinate system by
$$\omega(x_i) = \omega_{1\dotso n}(x_i) \;\lvert\di x_1 \land \dotsb \land \di x_n\rvert \;.$$
The "absolute-value" expression indicates that the coordinate $n$-form must be considered as inner-oriented with sign "$+$".
The inner orientation of $\omega$ at a point is given by the sign of $\omega_{1\dotso n}$.
Under a change of coordinates to $(x'_i)$ its new component is given by
$$\omega'_{1\dotso n} =
\omega_{1\dotso n}\; \biggl\lvert\det\tfrac{\de x_i}{\de x'_j}\biggr\rvert$$
taking the absolute value of the determinant.
From this formula it's clear that the inner orientation of $\omega$ at a point doesn't depend on the coordinate system, because the original sign of $\omega_{1\dotso n}$ is preserved.
An outer-oriented $n$D submanifold $C$ is again represented as a map $F$ from a subset $U \subset \mathbf{R}^n$ to our manifold, such that $F(U)=C$.
Its outer orientation has sign $\epsilon$, taken as "$+$" or "$-$".
In the coordinate system $(x_{i})$ the map $F$ is again represented by the functions
$$ x_{i} = F_{i}(u_{1}, \dotsc, u_{n})\;.$$
In these coordinates, where the inner-oriented $\omega$ has component $\omega_{1\dotso n}$,
the integral of $\omega$ over $C$ is given by
$$
\int_C\omega \equiv
\epsilon\int_U \omega_{1\dotso n}[F_i(u_j)]\;
\biggl\lvert\det\tfrac{\de F_i}{\de u_j}\biggr\rvert \;
\di u_1 \dotsm \di u_n \;.
$$
There is the absolute value of the determinant in this case, and note the $\epsilon$ in front of the integral. (Typically in such region integrals the sign of the submanifold is taken as "$+$".)
The absolute value in the expression above takes care of the fact that the component of $\omega$ has a different transformation, and that the outer orientation of $C$ has nothing to do with the coordinates $(u_i)$ (which define an inner orientation instead). You can easily verify that changing coordinates gives the same result.

de Rham's book [1984] discusses these matters very simply in Chapter II.
References

Bossavit, A. (1991): Differential Geometry: for the student of numerical methods in Electromagnetism https://www.researchgate.net/publication/200018385_Differential_Geometry_for_the_student_of_numerical_methods_in_Electromagnetism, especially § 3.2.
Bossavit, A. (1998): On the geometry of electromagnetism https://www.researchgate.net/publication/254470625_On_the_geometry_of_electromagnetism, especially part (2).
Burke, W. L. (1983): Manifestly parity invariant electromagnetic theory and twisted tensors https://doi.org/10.1063/1.525603.
Burke, W. L. (1987): Applied Differential Geometry (Cambridge University Press), especially chaps IV–V.
Burke, W. L. (1995): Div, Grad, Curl Are Dead http://people.ucsc.edu/~rmont/papers/Burke_DivGradCurl.pdf.
Burke, W. L. (1995b): Twisted forms: twisted differential forms as they should be http://www.ucolick.org/~burke/forms/tdf.ps.
Choquet-Bruhat, Y., C. DeWitt-Morette, M. Dillard-Bleick (1996): Analysis, Manifolds and Physics. Part I: Basics (rev. ed., Elsevier), § IV.B. Note expecially the remark at the end of page 212.
de Rham, G. (1984): Differentiable Manifolds: Forms, Currents, Harmonic Forms (Springer), Chapter II.
Marsden, J. E., T. Ratiu (2007): Manifolds, Tensor Analysis, and Applications (3rd ed., Springer), § 7.5.
Schouten, J. A. (1989): Tensor Analysis for Physicists (2nd ed., Dover).
Schouten, J. A., D van Dantzig (1940): On ordinary quantities and $W$-quantities. Classification and geometrical applications http://www.numdam.org/item/CM_1940__7__447_0.


Custom shape interaction in Figma

Question: When prototyping in Figma, is there any way to set up interaction exact on the shape and not the it's bounding box?
Answer: No
That's just not how Figma works.
You could break the shape into smaller shapes (so each part of your main shape would have a smaller bounding box) and set the same interaction for all the parts but that'd be going too far for just a prototype.

Custom shape interaction in Figma


what is context object design pattern?

Question: what is context object design pattern ?
Comment: If you provided some background information as to why you are considering this pattern you may receive a more positive response for people as it will invoke more interest.
Comment: See also: [Can you explain the Context design pattern a bit?](http://stackoverflow.com/questions/986865/can-you-explain-the-context-design-pattern-a-bit)
Answer: A Context is a collection of data, often stored in a Map or in a custom class which acts as a struct with accessors and modifiers.  It is used for maintaining state and for sharing information within a system. See this PDF for an indepth description. Though it can be used for efficient and effective data sharing, you should note that many are wary of the Context pattern as an anti-pattern.
Answer: An example for it might be the HttpSession object: you have attributes which is basically a map with String keys and Object elements. This provides state information between http requests. Another example is the ServletRequest which provides state information between Servlets.
Answer: See Can you explain the Context design pattern? for a thorough description of the pattern.
My post there also explains why it's not an anti-pattern - but the botched implementation of it is.
Answer: "Context" comes from "Contextual Information".
From Msu.edu:

Contextual Information: Information that is in addition to the actual text of the document, such as date sent, sender's identity, addressee's identity, routing information, and return receipts.

In most frameworks (and thus the design pattern), a Context Object stores information about an incoming request and corroborating a response.

what is context object design pattern?


What's the difference between a conviction that is spent and one that is expunged?

Question: This came up in the comments thread of this question so it was suggested to ask it.
Answer: Spent means the sentence etc has been served and, under certain conditions, one need not disclose one's criminal history as they are deemed rehabilitated. See the Rehabilitation of Offenders Act 1974 and NARCO:

Once a conviction, caution, reprimand or final warning becomes spent, you do not need to disclose it to most employers, or when applying for most courses, insurance or other purposes (e.g. applying for housing)...

Expunged means the conviction etc has been quashed as though it never existed. The online OED defines it as:

Obliterate or remove completely (something unwanted or unpleasant)

Note that the term used by in legislation is Quash[ed], as per section 2(2) of the Criminal Appeal Act 1968:

In the case of an appeal against conviction the Court shall, if they allow the appeal, quash the conviction.
Comment: So "expunged" means the conviction was wrong in the first place and should never have happened (in a perfect world)?
Comment: @gnasher729 no, expunged means the conviction is so old that it no longer appears on a criminal record. It does not mean that the conviction never happened. It is different from one that has been overturned or pardoned.
Comment: I think this comment should be integrated into the answer.
Answer: A spent conviction has had its punishment served.
An expunged conviction is one that has been served and is so old (I.e. there is a statutory time limit) that it can no longer be reported for particular purposes. Usually on a police record although there may be different grades of police record - you maybe expunged in some but not on others. For example, certain convictions may not appear on publicly available records but may be available to police or courts.
Comment: Do you have any reputable sources for this? Maybe things are different in your jurisdiction but "Spent" in E&W has a specific meaning beyond "punishment served" which is, near enough, the same as your definition of expunged.


Giving Battle.net realm items to an open character

Question: I've found some good necromancer items on a Battle.net realm with my sorceress. I know the opposite is not possible, but is there any hack to give these items to a friend who plays single player and TCP/IP games?
Comment: I'm not sure if there is, but I'm pretty sure there are plenty of mods for diablo 2 which can allow characters to have any items/stats they want. You could try looking for something like that.
Answer: The closest you can come to this is to download a diablo 2 character editor and adding an item into your inventory (if its a ladder only item such as a rune word or a unique charm, you can just create a similar item with the same stats as the rune word).
Comment: @sarmackie the editor will allow you set whatever bonuses you want onto an item, even those that are not normally possible, such as +7 to all skills and 250% resist all.  What you will have to do is to set the effects of the item to exactly match what the item is on the ladder.
Comment: This should do the trick for set or unique items. Would such editor allow to add ladder-only items to single player characters? And how about items that only have randomly generated mods (such as magic/rare/crafted items)? Are there any editors to create rare/crafted items with specific bonuses?


How could a winged human hide very big wings

Question: So I've seen a question similar to this one, but the wings were much shorter.
I've got a character that's about 5ft tall and has wings from about his shoulders to his calves. Think avian-human hybrid (he was one of the first test tube babies) he's unique and wants to hide his wings when he's going into towns and such.
How would I hide his wings? he couldn't just hide them with a jacket because of the length.
the difference between this and the other question is my character is very short. his wings are about the length of his entire torso, and my character can fly, albeit not easily, but he can fly.
Comment: A difference of one foot doesn't make this a unique question.
Comment: If it can keep the wings close enough to its body I would suggest some big robes, like some kind of monk
Comment: Concur with rek --- as written, the questions are functionally identical. Do your winged folk do anything with their wings that would sufficiently alter the question and thus make it not a duplicate?
Comment: I like Gargoyles where most characters would tuck their wings around their body when they were in doors or needed to reduce the body width for reasons.   Typically this resulted in a cape or cloak like effect of the wing (Used by Goliath, Hudson, and Broadway), or a wrap under the armpits much like a towel around a woman (used mostly by Demona and (the very much male) Brooklyn).   The only recurring character who didn't do this was Lexington, who's wings extended from his arms to legs like a flying squirrel.  He still had the two extra limbs which acted as supports half-way down the membrane.
Comment: Your edit doesn't tell us anything that can't be answered by the [other question](https://worldbuilding.stackexchange.com/questions/41239/how-could-a-winged-human-hide-their-wings), you may have tweaked your question, but not made it clear how the differences are not addressed there. You can [edit] again if you wish. People can have [long coats](https://en.wikipedia.org/wiki/Greatcoat).
Answer: Giant Hiking Backpack

He's never going to be able to hide them under clothing. It'll be too obvious there's way too much unaccounted mass there unless he also wears a fatsuit. Your best bet is to hide them under a large accessory it's seen as reasonably normal to wear on your back.
So give him a fake hiking backpack that doesn't actually have anything inside it. Make it go from the top of his head to below his back, and make it zip closed around his wings and hide them safely inside.
Another plus side is that, as the picture demonstrates, this works regardless of the weather, whereas any kind of solution involving bulky clothing is gonna look odd come summertime.
Comment: As far as I remember there is a fantasy race in Advanced Dungeons and Dragons, the Kenku, composed of winged humanoids that do exactly this. In later editions they are no longer winged it seems, but I remember them being so clearly in AD&D.
Answer: Pretend to dress up in costume.
Although I think that the two answers posted before mine are certainly more likely to work in an everyday situation, but if your character needs to potentially make a quick escape using his wings, he could dress the rest of his body as some extreme cosplay character or costume, which would not impinge his wings, but would definitely get some strange looks from passerby. This disguise works especially well during Halloween, or if he is part of a group of young people all wearing costumes.
Answer: Welcome to the site.
I believe that if your character can bind their wings, using two straps, they could

Hide them under a robe or a larger jacket of sorts.
They can break the straps in an extreme situation.

They could be held far back, and while it might cramp a bit, I think it's better than carrying around a giant backpack. The only issue is that if your character breaks off the straps in a situation that requires quick action, then you have to get new ones.
Hope this helps!
Comment: Can you clarify what it is that gets "broken off"?
Comment: Also, you don't really need to explain that you're "new"! In a couple weeks you'll be "old" and this answer will be here long after you're gone.


Separate table creation at runtime or add column

Question: I am planning to keep patient data in a patient table. I will have multiple Clients registered with me, and each client will have multiple doctors. Should I make patient table client wise or a single table with client and doctor ID field?
Comment: I'm having trouble understanding your question. Can you provide us with examples of your alternatives?
Comment: I think OP is taking about some health care application Database which supports multiple clinics
Answer: It is better to have single patient table.
Each doctor must have different UserId(or call PhysicianId) and then make entry in patient table with FkPhysicianId as a column and you can have one table for storing clinic information(auto incremented key can be used as ClinicId) and one for storing physicians Information like ClinicId etc.
single patient table will be better as you don't need to add table for each practice you add and data can queried using joins on these table and maintaining too many table in future will be problomatic and other implementation in the EMR application as well.
I would suggest to have a Master Table to assign auto incremented Id to physician and patient as well.


Get out of booting into Ubuntu on multi-OS Mac

Question: I installed Ubuntu on my iMac (Retina 21" late 2015) alongside macOS and rEFInd. Now, I believe the iMac boots automatically to Ubuntu in console mode. I tried a lot of combinations of keys, but without any result(option, command+R, command+option+P+R, etc.).
What should i do ?
Comment: Please, edit your question and include the output from the command `diskutil list`.
Answer: If you properly install Ubuntu 18 Desktop, then you should be able to hold down the option at startup until the Startup Manager appears. You then can select the icon representing macOS which should boot macOS. If you hold down the control while selecting the icon, then macOS will become the new default operating system to boot.
The Startup Manager should also show another icon which represents Ubuntu. Since the Startup Manager can be used to boot either macOS or Ubuntu, the use of rEFInd is optional.

If macOS does not appear in the Startup Manager, then you probably erased macOS when you installed Ubuntu.

If you choose to install rEFInd, then you should install rEFInd to separate EFI, FAT, or JHFS+ formatted partition. If you do this properly, then you can select rEFInd from the Startup Manager. In other words, the Startup Manager can be use to enable/disable rEFInd.

Note: You should not need to use the bless command or disable System Integrity Protect (SIP) to install Ubuntu or rEFInd.


Can the word 'celibate' be used for women too?

Question: Can the word 'celibate' be used for women too? Is there any 'ing' form of 'celibate'?
Can we also say,"She has become/turned celibate"?
Comment: OED do actually have an entry for ***celibate*** as a *verb* usage *(to restrain from marriage, compel to celibacy)*. But the only citation is from 1659, and they say it's a "nonce-word" anyway. Most instances of ***celibating*** today are likely to either be mispronunciations of ***celebrating***, or (either ignorant or facetious) alternatives to ***celibacy***.
Answer: The word celibate can be used for a woman too.
The Huff Post Entertainment has the headline

Lady Gaga Explains Why She's Celibate

I could not find celibating from any authentic source including COCAE.


Are there any Thunderbolt 2 external DVD drives?

Question: Sorry if this is off-topic or just a dumb question. I've got a Mac Pro with plenty of free Thunderbolt ports, but I'm using all the USB ports - are there any Thunderbolt external DVD drives available - I've been googling for about an hour but only found one really expensive Sonnet drive - which has way more functionality than I need.
Comment: Does it have to a Thunderbolt DVD drive, or would you be happy with some cable magic? You can get eSATA DVD drives, and Thunderbolt-to-eSATA cables: https://www.amazon.com/Goliton-Thunderbolt-eSATA-Adapter-Macbook/dp/B01I0VGF22/ https://www.amazon.com/Dell-Latitude-Precision-External-E-Sata/dp/9573213877/
Comment: I guess I don't mind using an adapter, but at the moment everything at the back of my mac doesn't use any, which is kind of neat-and-tidy! Thanks for suggestions!
Answer: You won't find a Thunderbolt 1 (much less and Thunderbolt 2/3) to an external DVD drive because there simply isn't any need to create one as USB 2.0 has more than enough bandwidth to accommodate even the fastest DVD drives on the market.
To understand why, we have to understand that the fastest DVD you will find is a 24x unit; most will be 16x.  The base write speed is 1x and a 1x speed is 1.32Mb/s so a 24x unit is about 31Mb/s.1
USB 2.0's transfer speed is 280Mb/s or about 35MB/s 2 so even the theoretical fastest DVD drive that you will ever find is less than the max limit of a USB 2.0 connection which, for all intents and purposes, has been obsolete since the beginning of 2009 (USB 3.0).3
There just isn't a need to create a DVD drive with a modern, high speed data transfer interconnect because it's a dying technology and it's fastest transfer rate doesn't even begin to exceed what is already backwards compatible with USB 3.0

1 Wikipedia Modern compact discs support a writing speed of 52X and higher, with some modern DVDs supporting speeds of 16X...
2 Wikipedia  USB 2.0 was released in April 2000, adding a higher maximum signaling rate of 480 Mbit/s (High Speed or High Bandwidth), in addition to the USB 1.x Full Speed signaling rate of 12 Mbit/s. Due to bus access constraints, the effective throughput of the High Speed signaling rate is limited to 280 Mbit/s or 35 MB/s.
3 Wikipedia The USB 3.0 Promoter Group announced on 17 November 2008 that the specification of version 3.0 had been completed...
Comment: But what about blu-ray?
Comment: @JoelCoehoorn 0 BR 1x transfer is 4.29Mb/s meaning its best possible x-fer rate is 102Mb/s at 24x (which I don't even know if those exist). So, it's not even half of USB 2.0 bandwidth.
Answer: You might want to take a look at Sonnet Technologies Thunderbolt 2 Docks:
Echo 15+ Thunderbolt 2 Dock (with Blu-ray Burner) - $499
Echo 15+ Thunderbolt 2 Dock (with DVD±RW Drive) - $349
A bit pricy, but a crap-ton of ports.
(From the Sonnet site:)
•       Connects Your Peripherals with One Cable—Connect your peripherals to the Echo dock; connect your computer to and disconnect it from the dock using one Thunderbolt cable
•       Provides Multiple Interfaces—Thunderbolt 2, USB 3.0, 6Gb/s SATA and eSATA, FireWire 800, Gigabit Ethernet, and audio
•       Adds a DVD±RW Drive to Your Computer—Includes an 8x DVD±RW drive to load software, import CDs, burn CDs and DVD-ROMs, and play DVDs
•       Supports Internal Hard Drive or SSD Installation—Install one 3.5" hard drive, or two 2.5" SSDs or hard drives inside the dock
•       iOS Device Charger—USB 3.0 ports can charge your iPad, iPhone, or iPod, even while the computer is disconnected, off, or sleeping; all four ports provide 7.5W, optimized for quick charging
•       Wide Range of Display Connection Options—Select from a variety of inexpensive Mini DisplayPort to popular display interfaces such as HDMI, DVI, VGA and Dual-Link DVI
•       Compatible with Every Thunderbolt Mac—Supports any Mac with a Thunderbolt port running OS X 10.9.5+
Disclaimer - I have no financial stake in Sonnet Technologies, and I have neither used nor tested any of these Docks. Sonnet has been around for many years and is a reliable company.


How to edit file from grub prompt in RHEL6?

Question: I changed the file which is in /usr/share/xsessions/gnome.desktop and now I want to change it back to its original state from a GRUB prompt because now my system is not able to login.
Comment: How are you not able to boot into your RHEL Linux? This file shouldn't render your system unbootable if it's corrupt. Switch to a virtal console with `Ctrl+Alt+F1` or similar to login without X and edit the file.
Comment: @htor, i tried this but nothing is coming.
Comment: The virtual consoles should still be there, just make sure you're holding down `CTRL-ALT` as you hit `F1` htor is right, even if this file were totally messed up, it would only stop you from logging into the desktop.
Answer: There is no way to edit a file from the Grub prompt. But you don't need to do that.
As htor and Christopher already suggested, you should be able to switch to a text mode console by pressing Ctrl+Alt+F2 and log in there and edit the file.
If for some reason you can't even get a text mode login prompt, boot in single-user mode. In Grub, edit the command line, add 1 at the end of the linux … line, and press Ctrl+X to boot. In seriously hosed situations, init=/bin/sh might work better than 1.
Comment: Edit the command line? What does that mean
Answer: To edit the command line, you just have to press the indicate key (for example, in the image, you have to press "e") in the Grub menu with the ubuntu option selected. This will open a screen with some parameters, so you gonna edit the line that starts with "linux" putting init=/bin/sh in the end like Gilles said and press ctrl+x or f10 to boot. In my case, I needed to edit some files to be possible to login then i had to change a parameter of the line from ro to rw.


How to upload/publish ASP.net MVC application to Godaddy on my domain

Question: I have developed the ASP.NET application in MVC using Visual studio 2010 express edition. I have domain on Godaddy. how to deploy the MVC application on godaddy ? What steps i need to follow?
Comment: which version of .net you are using? what is your hosting plan?
Comment: using 4.0 version with windows hosting plan.
Answer: 1) Publish you site on you local test machine.
2) Login to Control Panel of Go-Deddy.
3) From content select File  file manager and upload you content.
4) Give proper connection string.
That's it...........
Above is high level steps.. You can check for better explanations.
Answer: It's important to note that if your app is using MVC, you will need to bin deploy it for it to work on GoDaddy.  You will need to manually copy any MVC related DLLs that your project is using to your production bin directory.
Alternatively, you can set "Copy Local" equal to "true" in the Properties window for any of your MVC related project references as described in this blog post. Then when you do a Publish of your application, all of the needed assemblies will be included automatically.
Be sure to deploy the correct versions of the DLLs you need.
Answer: sure, you can deploy your MVC 4 application. Godaddy supports MVC 4. What I have done to deploy my MVC 4 application is:
1. I included DLLs such as:

System.Web.Mvc
System.Web.Routing
System.Web.Abstractions

2. I edited web.config file. I put next strings:
<code><system.web>
   <trust level="Medium"/>
   .....
</system.web>
</code>
3. Then I used the File System publish method and then I used FileZilla to transfer the files to the GoDaddy. I copied all files to httpdocs directory. You must copy just to httpdocs directory.
That's all. Good luck.


Prusa i3 pro W - not extruding

Question: I'm trying to do my first ever print with my Geeetech prusa i3 pro.
When I try to print that printer seems to work, x,y,z axis all moving ok.
What isn't working is that little to no plastic is being extruded.
The nozzle appears to be getting to temperature, and some plastic comes out whilst it's heating, but then when it starts to move and print, no plastic comes out.
My thoughts are:

Have I not loaded the plastic properly
Is the extruder engine not working i.e. not pulling the plastic through

Any hints on what I can try would be appreciated.
Comment: What did you do to troubleshoot already? What exactly does not happen? Do the Gears turn or not? Is the motor connected?
Comment: I've wired the motor in as per the build instructions. How would I know if the gears are turning are they not internal ? I suspect this is the case - it does not look like it is feeding the filament in at all.
Comment: There is exactly 1 gear on the extruder stepper motor: the one that tries to push the filament. As a good test, remove the filament.
Comment: OK, I've removed the fan and heatsink so I can get a better view of what is going on. Using the repetier-host I'm trying to drive the extruder motor - but I'm getting no movement.  If I've wired it in correctly (and I think I have) does this imply an issue with the motor itself ?
Comment: Is the extruder gear turning into the right direction?
Answer: Problem identified.
I took of the fan and heat sink so I could see what was going on in the mechanism that should pull through the filament.
Using repetier-host software I tried to manually drive the motor - nothing happening.
I swapped the A4988 stepper motor driver for the extruder with another (and my x,y,z axis motors work) to see what would happen - and it worked!
So just a faulty A4988 on the extruder motor.
I also manually pushed filament through the hot end to ensure there was no blockage and it worked fine.
So hopefully GEEETECH can send me a replacement and I'm good to go!

Prusa i3 pro W - not extruding


Raster Image Importation

Question: I am trying to open a raster image file in Arcmap 10.3 . I have the AUX File, a JGW file , 2 XML Document files ,and a RRD file. It imports into Arcmap 9. However, Arcmap 10.3 does not import the image. Can someone help me?
Comment: Separate the JGW and JPG files into a new folder (copy) then try. It could be one of the AUX files is bad, these files contain metadata and statistics - not so important if you just want to *use* the image but vital for extra information like accuracy and currency etc.. The RRD isn't supported as Wes said but should be just ignored. Does the image open OK in your default JPG viewer, it's not corrupt is it? Does the information in the world file (JGW) look right (6 numbers on 6 lines)? It should open in Notepad (or similar text editor).
Answer: RRD (reduced resolution dataset) files are no longer supported by ArcMap, since version 10.1 I believe. By the looks of that, you have an RRD, which is a pyramid set based on an original raster, but no the original data. ArcMap now uses a different type of pyramid with a <code>.tif.ovr</code> file extension. You should be looking for an associated jpeg, the original data. ArcMap will not open pyramid files alone, and the original raster will be needed.
The JGW file is a jpeg "world file" that gives it a spatial reference, and the AUX file associates the RRD with the original file, and the two XMLs are likely metadata and processing information.
EDIT: One option you might have--and I'm not 100% positive this will work because I do not have access to ArcMap 9--is to import the file into 9 and export it as a raster dataset of some kind (like a jpeg or tiff) and then import that new file into ArcMap 10.3.
Comment: Sry @Wes. the original .JPG file is included as well. But i should try changing the format from Arc 9.

Raster Image Importation


Word for people older than the speaker in school?

Question: I'm looking for a word for what you'd in the workplace call 'seniors', i.e. "My seniors told me where the cafeteria was in Building 1." But in college, 'senior' has a different meaning, and "upperclassmen" doesn't quite work. How should I refer to students in the years above me?
Comment: In Indian schools and colleges, we just refer to them as _seniors_ and _juniors_ if they are in a class above or below ours. As in, _I have a crush on a junior girl of my college_. So, I think it'd be better if you mention your country/region..
Comment: The single-word request  tag is for questions seeking a single word that fits a meaning. To ensure your question is not closed as off-topic, please be specific about the intended use of the word. YOU MUST INCLUDE A SAMPLE SENTENCE demonstrating how the word would be used.
Comment: I like the word 'grandee', myself.
Comment: They are your *elders*.
Answer: Here in the US, we do not use seniors to mean those above you in the workplace.  Generally, if they are higher than you in the organization, they are called superiors, although if ranking by time served grants you certain privileges (like who gets laid off last), you may say you have seniority over (or even you are senior to) someone else.  If they are below you, they might be called your underlings, or occasionally, inferiors.  If they are merely older or younger, or working there longer/less time, there is no specific term for that relationship.
In US high schools and colleges/universities, junior and senior have specific meanings; respectively, third- and fourth-year students.  First- and second-year students are, respectively, freshmen (which is traditionally gender-neutral, but problematic to some, because of the "man" in it) and sophomores.
So that leaves the problem of what to use to refer to students in grades above or below yours.  The only solution I can come up to make clear what year you are and then refer to the specific year students you mean:
As a sophomore, I find the insights provided by the juniors and seniors to be very helpful in making my course selections.
Of course, if you are a freshman, using upperclassmen could mean "everyone else, from sophomores to seniors."  (Many dictionaries say that an upperclassman is either a junior or senior.)
Comment: I was not aware that an [upperclassman](https://en.oxforddictionaries.com/definition/upperclassman)  could be a sophomore.
Comment: I see that many dictionaries define upperclassman as only a junior or a senior.  But https://talk.collegeconfidential.com/university-pennsylvania/1186848-what-is-considered-upperclassman-at-penn.html shows that although this definition is common, the definition as "anyone but a freshman" exists as well.  To me, if it's a freshman talking, it probably means "everyone above me."  I've changed the answer somewhat to reflect this.  See also https://www.theodysseyonline.com/difference-freshmen-upperclassmen and http://parents.wfu.edu/my-student-is/upperclassmen/.
Answer: In college we don't typically refer to others as senior or junior (in the US at least). The closest we have is upper and lower classmen, but they aren't used often. I'd avoid it, unless you are trying to point out their advanced knowledge (use "Senior", "Junior" or "Sophomore").
I'm not sure if this answers your question, but it might help:
https://ell.stackexchange.com/questions/60815/how-could-i-address-students-in-a-higher-grade-than-me


SFMC-Query the All Subscribers count on a specific date?

Question: I need a query to count the number of active subscribers on specific dates, January 31, February 28, etc. throughout the year into a data extension. I know this will be using the _subscribers data view. Does anyone know how to structure this query to pull count on a specific date?
Comment: I removed my answer, since i re-read your question, there is not a way to determine number of subscribers active on a certain date, you the datview has a joindate and an unsub date
Answer: I don't see an easy way to get historic data you're looking for using SQL in Marketing Cloud. Maybe it would be possible if you download all your subscribers and analyze it in Excel?
Anyway, if you need this for future as well, you'd have to start logging it first to be able to use that data later. Start with a daily query to write the daily count of subscribers into a simple DE and once you start gathering data, you will be able to further use it and analyze it.
SQL query:
<code>SELECT
COUNT(SubscriberId) AS NumberOfSubscribers
FROM _subscribers
WHERE Status = 'Active'
GROUP BY Status
</code>
Data Extension:

Field 1, "NumberOfSubscribers", type: number, non-nullable
Field 2, "Date", type: date, non-nullable, default value: today's date

You need to set this up in Automation Studio and schedule to run on a daily basis.


How can I test my camera-dependent android app on most devices?

Question: We are developing an app for taking photos faster. We do this by actually taking videos instead of photos and processing the individual images in the video on the fly and combine them to create a high-resolution image. Since this app is heavily dependent upon the hardware of the various devices, I was wondering how we could go about testing this on, say 50% of devices in one go? Are there for example groups of people that allow for all sorts of people to run tests on their devices? I would be willing to pay for each test on each on each device. What are my options?
Comment: A simple breakdown of services are: walk-in vendor labs, device rentals, full-service app testing services (where you provide test directions and the provider's staff will run down the instructions manually on the devices they own). What is more interesting is how you implement device-specific workarounds in your software, which is answered in the link mentioned by @gnat.
Comment: Keep in mind that despite your testing efforts, most "device-specific workaround" are discovered only after the public release of software. As a result, changes to the software workarounds can only be implemented after the initial release, and you have to prepare for rapid update releases on a continuous schedule as soon as a new workaround has been found and implemented.
Comment: Also see http://android.stackexchange.com/
Answer: There are services out there for this sort of thing. This article mentions some. Searching for something like "android device testing" should also lead you to some. Obviously you would need to evaluate which service gives you the functionality you need.


How to apply group policy settings to specific local accounts in Windows

Question: I created a limited user account and want to restrict USB and CD drive access using group policy settings. Hence I want to use gpedit.msc to enforce restrictions on the limited account and disable access to USB and CD drive, and prevent the limited account from modifying those changes. How can I achieve this without restricting any other accounts?
Answer: In Windows Vista and later you can apply policies only to a specific account, but you have to load the group policy object editor from the Microsoft Management Console, not by opening the snapin directly.

Open mmc.exe
When the MMC console opens, click "File" -> "Add/remove snapin"
Select "Group Policy Object Editor" and click the "Add >" button
In the dialog which appears, click "Browse".
Click the "users" tab and select a user.

Click "OK", then "Finish", then "OK" again

You will now have a group policy user object for the selected user. Apply whatever restrictions you want. You may be interested in checking out "Hide these specified drives in My Computer" in User Configuration > Administrative Templates > Windows Components > Windows Explorer.
Comment: Makes me sad how hidden this is. Took me a while to find a solution and I finally came across your answer. It's great, thank you!
Comment: @Pacerier if you don't open it through mmc, it'll apply the policies to the whole computer. When you open through mmc, you can choose whether to only apply them to a certain account.
Comment: @nhinkle What if I wanted to apply the same policies to more the one user on a non-domain Win7? Is there a way to copy them?
Comment: @AJaM I am not aware of a way to copy them. Unfortunately, you'd have to do it for each individual computer.
Comment: @nhinkle, Why is it different when we open it in `mmc`? What's the reason for that?
Answer: You would have to makes these group policy changes from an administrator account, not from the limited account.
Comment: Tried that but it applies to all accounts, how do I make changes to just the limited account?
Comment: Correct me if I'm wrong, but isn't the group policy item to disable USB access in the Machine configuration?  If that's the case, it doesn't matter which account you make the change under, it will affect all users of the computer.
Comment: oh! if that is the case how do I restrict a limited user account. I don't want to limit the admin account, just the user account is all that I want to restrict
Comment: @Rogue, I posted below about the USB devices.  I'll think some more about the CD drives and edit when I figure something out.  I feel like I'm missing something obvious here.
Answer: For restricting access to USB devices, Microsft has a KB article about denying permisison to certain files - http://support.microsoft.com/kb/823732.  You might need to leave SYSTEM with access to the files for the other accounts, some trial and error is in order.
EDIT-
There seems to be some fairly affordable third party software that does what you're looking for, but I've not tested it myself.  http://www.devicelock.com/
Answer: (I post "an answer" because I have not enough reputation to comment above. However, this information is important.)
Tested: Windows 8.1
The answer given by nhinkle above works well. However, it does not prevent you from opening a command prompt and navigate to the drives manually. Starting a JPG file on the other drive opens the image viewer.
You can disable the command prompt via "User Configuration\Administrative Templates\System", but I haven't found a way using the MMC to allow the command prompt while restricting it from navigating around.
There is a workaround, by accessing the "Security" "Properties" (right click) of the drive/root folder(s) (like D:), adding a dedicated line for the user account in question and check "Refused" "[x] Total Control" (might be labeled differently, I use a non-EN Windows version).
Comment: This is really a comment and **not** an answer to the original question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient [reputation](http://superuser.com/help/whats-reputation) you will be able to [comment on any post](http://superuser.com/help/privileges/comment).
Comment: As I said, I'm aware of this. And this is not a critique nor a request. It's an additional information that I judged important to know. My systems are fine, but it would be too bad if people using the method above would think being in security while they aren't. If you judge this information not worth keeping in 'the wrong place", feel free to remove it.


Coldfusion consuming webservice -> java.net.SocketTimeoutException: connect timed out

Question: I'm consuming a webservice over Coldfusion 9 for getting property data and saving the result to our local database. The script gets executed via scheduler once a day. The problem is that sometimes it throws an error (see below).
Basically I'm getting a list of IDs (one request to get this list) and loop over the result with one webservice request for every ID (~150 requests).
Sadly I can't get the detailed data for all properties in one request.
I tried already setting -Dsun.net.client.defaultConnectTimeout=10000 in the JVM Arguments - same result ...
"Error","jrpp-7225","10/22/11","03:00:32",,"Cannot perform web service invocation properties.
The fault returned when invoking the web service operation is:
AxisFault
    faultCode: {http://schemas.xmlsoap.org/soap/envelope/} Server.userException
    faultSubcode:
        faultString: java.net.SocketTimeoutException: connect timed out
        faultActor:
            faultNode:
                faultDetail: {http://xml.apache.org/axis/}stackTrace:java.net.SocketTimeoutException: connect timed out
                at java.net.PlainSocketImpl.socketConnect(Native Method)
                at java.net.PlainSocketImpl.doConnect(Unknown Source)
                at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
                at java.net.PlainSocketImpl.connect(Unknown Source)
                at java.net.SocksSocketImpl.connect(Unknown Source)
                at java.net.Socket.connect(Unknown Source)
                at sun.reflect.GeneratedMethodAccessor191.invoke(Unknown Source)
                at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
                at java.lang.reflect.Method.invoke(Unknown Source)
                at org.apache.axis.components.net.DefaultSocketFactory.create(DefaultSocketFactory.java:15...

Any ideas on this one? What is causing the timeout: a slow remote server? our server which cannot open more sockets for new connections?
Answer: You might have to do the webservice requests in smaller batches. Use a DB or some other persisted variable to store the initial list of 150 ids, and then do 1-50, 51-100, etc in separate cfschedule calls. You can update the properties of the scheduled job in code to set the interval to 61 seconds while processing the batch, and then reset it to the original values once all batches are complete.
Comment: The error seems to occur on every index of the loop. Any other suggestions? Any idea how to increase the timeoutlimit (applicationwide would be great but serverwide would be ok too)?


Is 23/32 plywood too thick, heavy to be used as underlayment over 3/4 plywood subfloor?

Question: I am finishing a project started by someone else so I don't know the logic behind material selection. It's a second floor Accessory Dwelling Unit stripped down to the 3/4 plywood subfloor except for where a few new sheets of 23/32 tongue and groove plywood were laid, floating on the subfloor. Before I continue what was started I want to make sure that laying such thick plywood for underlayment is okay, not adding too much weight and if so should it be secured or left floating? It seems excessive to me and will defiantly lead to me having to reframe doors and such.
Comment: By "floating" I assume you mean it's just laying there unfastened.  There's no reason to put something like that in permanently.  Are you sure it's not there to temporarily cover up whatever's underneath it like bad subfloor?  Or just hadn't gotten around to fastening it down?
Comment: Welcome. Please take the [tour].
Comment: Pull a sheet up, or is it glued and screwed? Then maybe just under cut the doors some more. Which if there's no HVAC returns, need to be anyway.
Comment: Thank you all for the input, I tried looking up building codes for the answer but in this case I couldn't quite understand the terms used. I called it floating just because it's not been secured to the original subfloor, your guess is as good as mine whether that was intentional or not.  I see a couple spots where the second layer of plywood hadn't been laid where the subfloor was cutout and replaced, poorly executed.
Comment: IIUC, you've got 3/4" (24/32") plywood subfloor, then somebody left a few sheets of 3/4" (23/32") plywood laying about ("floating") on top of it and you're wondering if it's OK to clean up the mess? Your description of a "few new sheets" implies to me that they're just laying there, even if the T&G have been pushed together and the fact that they're "floating" (not fastened) means you can move them at will. I'd definitely recommend moving them to see what's underneath!
Answer: 1½" is not at all too much. It's about ideal, actually, if you have the space available for it. Ceramic tile requires nearly that much, at a minimum.
Your followup question has been well addressed already:
When installing two layers of subfloor, is it okay to secure both layers to joists?
Proper way to install double-layer of subfloor?
Plywood underlayment over plywood subfloor - how to secure
How best to join 2 layers of sub floor?
What is the proper way to add another subfloor layer?


What is the maximum number of players in Texas Hold'em?

Question: I've been told the maximum number of players at a Texas Hold'em table is 10. Why?
Answer: The ideal max number at a regular-size table is 9 players and a dealer. 10 is also not uncommon. Some larger tournaments will occasionally place 11 at a table in the early stages until the field is narrowed a little.  Any more than that and you'll have a game that is super tight, both in terms of the poker and the space available to you. The theoretical max at a table is limited only by the number of cards available in the deck.  52 cards, and 8 are used up as part of the board (5 cards shown plus 3 total burn cards). That leaves 44 cards remaining, and each player gets 2 of them, so I guess you could have 22 players if you had a big table and skinny people. Of course, a game like this would be no fun for anyone, dealer or players.
Comment: Agree. I would like to add that the more the number of players increase, the tighter you can play because the blinds will come slower to you.
Comment: And no (or only one) burn card(s) would allow for 23 players total.  Still, dealing out nearly the whole deck, even with everyone playing super-tight it seems that somebody would have a good enough starting hand to open more often than not.
Comment: At 22 hand someone would have  pocket aces like 1/10 hands.
Answer: In the 80s I played in clubs that routinely spread 13-14 hands on a big table (often a "violin" table more commonly used for Baccarat). That's very unusual nowadays, since casinos know that slows down the rake, so most spread only 9 or 10 now.
Theoretically, without burns, you could have 23 players. Early Internet games on IRC would spread a tournament this way, and it was a quite playable game.
Answer: the community cards need to be eight, 4 on the flop, two on the turn and river. leaving 44 cards for player hands or max of 22 players, this might be interesting online, but in a casino, you would likely be bored to distraction IMHO. this is enpough for an 11 handed Omaha game.
Answer: 10 Is max, more players would just kill the game... If you play poker for a longer time I think you would agree with me. I prefer to play 6max on cash game, it's faster and more skilled.
Think if 20 people sat on one table. They would rarely pay blinds and everyone would be waiting to hit some strong hand and nobody would play which kill the thinking game of poker.
If you try to play heads up tons of play is around bluffing and exploiting your opponents weaknesses which is very fun.
Comment: This is not an answer.
Answer: More the merrier!  I'm on my 43rd home game,  12 was usually my standard midweek turnout at a single table.  That was never a problem - also sometimes a couple more would just join
I have a 10c ante with 25c small 50c big blind. So the more players actually made a decent pot - last man standing still gets some coin even with folds
Having more than 09 is a good idea in my real world experience
22 is the max if you spent the whole deck!
Answer: I think above 10 would start to kill the games, you've got 40 cards out already, those that call with marginal K9, Q8, A5 are disadvantages because what's probably left with the 12 cards left is garbage. The chances of a pair is reduced to 1 in 10 resulting in raises and folds pre flop and very little action.


Can I put a switch in after a GFCI and still have proper protection?

Question: I am about to install a fan in the shower stall.  It is code to do so as long as the fan is GFCI protected.  However, I don't want the switch that controls the fan to turn the receptacles on and off.  So, this is the plan:  MAIN CIRCUIT to GFCI to REC #1 to REC #2 to SWITCH to FAN.  I know that everything after the GFCI is protected; but I want to make sure that putting a switch in the chain isn't going to mess anything up in terms of proper GFCI protection for the fan.
Comment: There is no problem with what you want to do.
Comment: The only way that the switch could turn off the receptacles would be if it is in series with them.
Answer: A configuration with GFCI protected outlets and switched lights but and unswitched outlets is a completely ordinary and unremarkable configuration.


Potassium Permeability in Cardiac Muscle Cells

Question: From my research it seems as though there's a difference between cardiac and skeletal muscle cells in that during depolarisation, the permeability of potassium actually decreases for cardiac muscle cells. How does this occur? I imagine it would be due to the closure of potassium channels but if this is the case, then how is the inwards current of calcium balanced during the plateau phase?
Answer: In skeletal muscles, depolarization occurs via opening of voltage-gated sodium channels, leading to influx of sodium ions, and opening of potassium channels. However, in the case of cardiac muscles, during depolarization, voltage-gated sodium channels open, and influx of sodium ions leads to closure of potassium channels, which eventually leads to the long action potential and plateau phase. In cardiac muscles, co-occurrence of calcium channels also occurs.
You can find more details here


Prior Art on 2022/0168762

Question: I am familar with CO2 snow cleaning.  In section 0006 they state "conversion of liquid
CO2 into CO2 snow only takes place in a mixing chamber in which liquid CO2 is expanded into a carrier gas which is also supplied."  The implication that a carrier gas is always needed.  ACP nozzles require a carrier gas.  Yet, in US Patent 4,806,171 Whitlock demonstrated an efective CO2 nozzle that does'nt need a carrier gas and still can remove submicron particles.  Plus, that nozzle was a Lavel (asymmetric venturi) design.  Does this prior art negate the claims presented here?  They are doing a multi stage expansion over many steps.  Whitlock just had two steps.  I think the Patent office should ask them about Whitlock.
US20220168762A1
Answer: I think your quote is a bit ambiguous. Here is the full sentence:

From WO 02/075799 A1 and also from U.S. Pat. No. 7,762,869 B2,
non-generic devices for generating a CO2 snow jet are known in which
the phase conversion of liquid CO2 into CO2 snow only takes place in a
mixing chamber, in which liquid CO2 is expanded into a carrier gas
which is also supplied.

I don't read this as stating that conversion of liquid CO2 to CO2 snow only takes place with a carrier gas, as you state, but is so in the cited documents.
This isn't my field, but Whitlock is clearly relevant. However, my reading of claim 1 of US20220168762A1 shows a different nozzle configuration from Whitlock so Whitlock doesn't necessarily invalidate US20220168762A1. Based on the number of citations of Whitlock, I would highly doubt the patent examiner would overlook it when evaluating patentability of the application. Just because Whitlock doesn't use a carrier gas doesn't mean another invention couldn't.

Prior Art on 2022/0168762


Return the last word of the url and capitalize the first letter

Question: Can the below code be done in one line? Do you think it should or is it ok like this?

function() {
var str = {{Click URL}};
var str1 = str.split('/').pop();
  return str1.charAt(0).toUpperCase() + str1.slice(1);
}
Answer: Seems alright, though the names str and str1 aren't very descriptive names. Also, indentation is inconsistent.
I'd also point out that your code obviously isn't real code (which technically makes it off-topic for Code Review) due to the {{Click URL}}. I can still tell what's going on, but in the future, post the real code. Or at least post a working piece of code where the function takes a URL as its argument or something, rather than having a hard-coded syntax error!
But beyond that: URLs can be complex. While I'm sure this is built for a very specific purpose, and you're expecting URLs that look a certain way, it'd be nice to make it more robust.
Firstly, the URL can have a trailing slash which would cause your code to find an empty string.
Also, a URL can have a query string like ?foo=bar or a hash/fragment like #heading-2 appended. Your code would treat such things as part of the last "word" in the URL (or maybe the query string contains slashes too, which would split the URL in the wrong place).
Lastly, URLs can contain percent-encoded characters, which won't be decoded by your function.
Some test cases:
http://example.com/something           => "Something"
http://example.com/something/          => ""
http://example.com/something?q=foo     => "Something?q=foo"
http://example.com/something#id123     => "Something#id123"
http://example.com/something?q=foo#123 => "Something?q=foo#123"
http://example.com/some%20thing        => "Some%20thing"
http://example.com/something/#id123    => "#id123"
http://example.com/some%20thing?q=foo  => "Some%20thing?q=foo"

I trust you can see the problem.
Something like this is more robust, though I don't guarantee it's bullet-proof:
function lastWordCapitalized(url) {
  return url.replace(/^.*\/([^?#\/]+).*$/, function (_, word) {
    var word = decodeURI(word);
    return word.charAt(0).toUpperCase() + word.slice(1);
  });
}

Which returns
http://example.com/something           => "Something"
http://example.com/something/          => "Something"
http://example.com/something?q=foo     => "Something"
http://example.com/something#id123     => "Something"
http://example.com/something?q=foo#123 => "Something"
http://example.com/some%20thing        => "Some thing"
http://example.com/something/#id123    => "Something"
http://example.com/some%20thing?q=foo  => "Some thing"

I should add, that all of this is assuming that

You're always dealing with absolute URLs. A link tag's href might just be "..", which is perfectly valid, but in which case there isn't much to display.
You always have some sort of path in the URL. If the URL just points to the domain's root (e.g. http://example.com/), you'll just end up upcasing the domain name.


Holding / Possessing / Earning / Attaining a degree

Question: I would like to say "people hold a university degree". Can I paraphrase it as "people earned/possess/own a uni degree"?
Also is it possible to say "He attained/achieved a higher degree of education than the others?"
Thanks!
Comment: Thanks. Can you say "people hold/possess/earned/own a university degree? Are all these forms correct?
Comment: I wouldn't use "own", which implies *property*: can you sell/trade/transfer a degree? PS please [edit] your post to correct it as per @jsw29's comment.
Answer: There are several questions here.
(1) Can one replace hold a university degree with has earned a university degree?
Yes, the two terms are interchangeable, insofar as one holds a degree if and only if one has earned it (setting aside some highly unusual scenarios). The two terms, however, direct the attention of the audience in subtly different directions. If one uses hold, one is focusing on the present, on the fact that the person has the degree now, and is thus, for example, qualified to take some job. If one uses has earned, one focuses on the past, on the process of working towards the degree (it may thus be a particularly apt term to use if one is describing how hard somebody worked to get the degree).
(2) Can one replace hold a university degree with possess a university degree?
Yes, one would be readily understood if one used possess. It is, however, not clear why one would want to do that; hold is likely to sound better in most contexts.
(3) Can one replace hold a university degree with own a university degree?
No, using own would be awkward, for the reason pointed out by Chappo in the comments. Saying that something is owned would normally be understood to imply that it can be bought and sold.
(4) Can one say 'He attained/achieved a higher degree of education than the others'?
Yes, but is should be noted that degree has a different meaning there than in the other questions. One can speak of 'a higher degree of education' even in a context that deals with informal education, in which no degrees (in the sense in which the word is used in (1)-(3)) are awarded.
Comment: Amazing! Thanks a lot jsw29. I really appreciate your detailed answer!


suricata url_decode and base64_decode

Question: In Suricata 6.0.0 beta 1, I noticed that the url_decode rule keyword is added.
And why url_decode supported in transformation while base64_decode implemented in another way? For example, it needs base64_decode combining with base64_data to alert?
It seems more reasonable to design the base64_decode in transformation just like url_decode.
Answer: Well, I guess base64_decode can support all kinds of buffers instead url_decode is not applied to all buffers yet.

suricata url_decode and base64_decode


Change color of cursor in UITextField

Question: How can I change the color of the cursor in my UITextField?
Comment: You need to clarify if you're working with Cocoa or Cocoa touch. You could have made this clear by putting actual class names in your question.
Answer: With iOS 7 you can simply change tintColor property of the UITextField. This will affect both the color of the text cursor and the text selection highlight color.
You can do this in code ...
textField.tintColor = [UIColor redColor];

...
In Swift 4:
textField.tintColor = UIColor.red

...or in Interface Builder:

You can also do this for all text fields in your app using the UITextField appearance proxy:
[[UITextField appearance] setTintColor:[UIColor redColor]];

In Swift 4:
UITextField.appearance().tintColor = UIColor.red

Below are simulator screenshots showing what an otherwise ordinary iOS 7 text field looks like with its tint set to red.
Text cursor screenshot:

Text selection screenshot:
Comment: Strangely for me it DOES NOT WORK if you set it in interface builder: I suspect the item shown is for the UIView itself, "not" the text field aspects per se.
Comment: Same as @Joe Blow, it's working only if you set it programatically. Moreover, it wasn't working on the simulator too, only on a real device. Strange
Comment: It is unbelievable to me that this nonsense is being promoted as an actual solution. This just changes the tintcolor of the text field, which if not white, will modify a lot more than just the cursor. Please DO NOT USE THIS.
Answer: In iOS, UITextfield has a textInputTraits property.  One of the private properties of UITextInputTraits is insertionPointColor.
Because it's an undocumented property, setting a custom color will probably get your app rejected from the App Store.  If that's not a concern, this should work:
[[addNewCategoryTextField textInputTraits] setValue:[UIColor redColor]
                                             forKey:@"insertionPointColor"];

Comment: My app was not rejected for using this. However in iOS 10 this solution causes a crash because the `insertionPointColor` trait was removed. **Do not use this solution anymore!**
Comment: This works great in iOS 6. In iOS 7 use the tint color. I will let you know if the app gets rejected, but others have used this trick with no  issue.
Comment: If it is undocumented (private), then you are almost certain to be rejected by Apple.
Answer: [[self.searchTextField valueForKey:@"textInputTraits"] setValue:[UIColor redColor] forKey:@"insertionPointColor"];

Answer: If you are developing on Mac OS X, then you can try the setInsertionPointColor: method. See NSTextView reference for more details.
Comment: Not if you're using `UITextField` objects you're not. That's iPhone SDK only.
Comment: That was part of my answer: this message only applies to Mac OS X, not the iPhone.
In your question, you have not specified the platform you are developing on. So I have assumed that it was Mac OS X...
Comment: Yes I tried it by using as:
[addNewCategoryTextField setInsertionPointColor:[UIColor redColor]];

But Im getting the warning as:UITextField may not responds to -setInsertionPointColor
Comment: And when I used the function as:
[addNewCategoryTextField setInsertionPointColor:[NSColor redColor]];
An error is genereted as NSColor not declared use in function.
Answer: Durgesh's approach does work.
I also used such KVC solutions many times.
Despite it seems to be undocumented, but it works. Frankly, you don't use any
private methods here - only Key-Value Coding which is legal.
It is drastically different from [addNewCategoryTextField textInputTraits].
P.S. Yesterday my new app appeared at AppStore without any problems with this approach. And it is not the first case when I use KVC in changing some read-only properties (like navigatonBar) or private ivars.
Comment: @Sathish In fact, it's an answer! would it be worth if he has posted a comment?
Answer: To change the cursor color throughout the app for UITextField/UITextView, appearance proxy can also be used as below,
UITextField.appearance().tintColor = .green
UITextView.appearance().tintColor  = .green

Change color of cursor in UITextField


Would an Electron Gun create thrust in space?

Question: Using solar panels, and the resulting electrical energy, could an electron gun provide a suitable level of renewable thrust, better than an Ion thruster? If it would even create thrust at all that is.
Answer: Partial answer:
Incident light on the solar panels will impart a momentum:
The momentum of a departing electron will be
$$p = m_e v$$
Ion thrusters use heavy ions (such as xenon ions which are 235,000 times as massive as electrons) to get a greater impulse. From this figure alone, one can see that the propulsion from electrons alone would be quite small.
Also, keep in mind that when an electron is ejected from the gun, it leaves the rest of the device with a positive charge, which will increase the ionization energy. Ion thrusters get around this by ejecting high-mass positive ions with small-mass negative ions to retain a constant overall charge.
I know that's not a definitive answer to your question, since you're asking whether over very long time scales, such a device could eventually overcome this limitation.
Comment: It might be a better to show the impulse as a function of power. Oddly this is very similar to the reason a human-powered helicopter uses the largest area of fans it possibly can: because the power needed to get a particular thrust goes by the velocity of the reaction mass.
Comment: Yes that makes sense, for modern applications it seems then that the Ion Thruster is the most optimised system, thanks for your answer!
Comment: @JamesonDennelly If you think it's a good answer, mark it as the accepted answer. Both you and I receive reputation, and it shows the community that it is a good answer. Welcome to Stack Exchange by the way.
Answer: There is another aspect to this, that is the level of energy imparted to the electrons, and the quantum state they are in.There will come a time, when we have the ability to impart near relativistic velocities to particles, and to change the way they behave. Bunching electrons into large Bose Einstein condensates will enable the macro effects of like charges acting repulsively to be more efficient in creating packets of thrust. However, you still can't get around the fact that you are limited by the initial rest mass of the electron, which means that although you can get some thrust when at relativistic energies, it still requires vast amounts of power to get them there, the only advantage of this system is that light is everywhere, and your "fuel" source is virtually inexhaustible, albeit orders of magnitude less and less effective as you move away from strong sources of photons, ie, stars...the better solution is to utilize matter, either as particles or ions, with a wide range of usable feed stocks is the way to go.


Using the same letters of Recommendation from previous admission cycle

Question: My question is geared toward Math PhD programs, but perhaps I will broaden it a bit, so it serve useful for future questions. Hypothetically, if you applied to a graduate program and didn't get in a given admission cycle, is it viewed negatively by the admission committee if you applied to the same institution with the same letter writers next year of the admission cycle.
Comment: You should always try to get newer up to date, letters, if the first set didn't work. From personal experience, if it doesn't work the first time, trying again with the same package typically doesn't provide you a major benefit.
Comment: It can be the same writer, but have them update with what you did in the year or 6 months between. And get a new writer for what you did that extra year.
Comment: What if a component in one's application other than the letters was weak and improved upon the next admission cycle, is using the same letter writers viewed negatively by the admission committee?
Comment: @Compass When you mean up to date letters, do you mean different letter writers?
Comment: @Compass Can you please turn your commends into an answer so that I can vote it up?
Answer: You should always try to get newer, up-to-date letters, if the first set didn't work.
You should try your best to get a letter specifically from the gap year, such as work experience or another type of academic program, that would benefit you greatly.
From personal experience, if it doesn't work the first time, trying again with the same package typically doesn't provide you a major benefit and ends up being you wasting money for admissions fees.


Raspberry Pi losing power

Question: We are building a Raspberry Pi with 2 servo motors connected to one power supply. But whenever the servo motors are provided with a signal to power and then move, the raspberry pi's green light turns off, and then when the servo motors stop moving, the green light comes back on. We assumed that this is a loss in power but when we measured the voltage throughout the circuit, we found it to be a consistent 5 volts. Is there something else going on here? Does the raspberry pi's green light not necessarily mean it has power?
Comment: Did you measure the power source output? Is that constant?
Comment: Preferably you should not use the same power supply for servos and a computer with delicate storage state such as a raspberry pi.
Answer: If the power drops very quickly (which is the case when the servos start to move and you did not provide enough capacitance), you are not able to measure this (short) power drop with a standard multimeter. (according to this site, green LED is SDCARD access and does not monitor power).
Solution: You need to provide (a lot) of capacitance (like e.g. 2x 470uF) to the servos.
Best would be to have a seperate power supply for the servo and the pi.
Comment: Capacitors won't be enough in the case of a servo mechanical stall, that would probably cause the pi to brown out and brings a risk of file system corruption.
Answer: The green light is Read/Write activity from your storage device (sd card, hhd etc) it has no reference to any GPIO activity. As for your 5V power, its is as good as what you bought to power the PI, so current capacity are really limited to the USB3 power port, the pcb lands up to the header. I wold say at the most power it could handle without board damage would be around 10A but I would de-rate this rating for temperature and safety margins down to 6.5 A.
Your "green light off"  just means the computer finished loading your program, and its doing nothing but executing your code in memory.
Answer: The green light on the Raspberry Pi that you are talking about has nothing to do with power warnings. If the light is constantly lit, then it means that the connection between the SD card and the Pi was successful. If it is consistently blinking, it shows that the Pi is either reading or writing from the SD card.
Now if you are suspecting loss of power, you might want to consider using a more heavier power supply. Or you could also use a DC-to-DC boost converter. They step up the input voltage to a higher output voltage. Hope this gives some idea!

Raspberry Pi losing power


Getting 404 when accessing xml file having german characters in name on IIS6

Question: I have a web application developed in ASP.NET. This app is setup on IIS 6 on windows 2003 server and same application setup on on IIS 7.5 on windows 2008 server. I have some xml files on root of the website having special characters in german i.e. ä,ö etc. When I try to access this file for example:
http://mytestxml.com/äötest.xml , it is accessible on IIS 7.5 but when I try to access the same on IIS 6, it comes up with 404 error. Just want to mention that nothing has been done to make it work on IIS 7.5.
Could anyone please suggest on this issue. how it could be resolved? I am really getting troubled with it and need to resolve it asap. Any help would be greatly appreciated.
Answer: I had this problem on IIS 10 and marking "Allow high-bit characters" in IIS Request Filtering settings fixed it for me.


iOS BLE Bluetooth - send/receive HEX data

Question: I am creating an iOS application that should connect to a custom BLE device. I need to iOS app to send 2 HEX commands, one to enable a part of the device and another to request for Data.
Is there any way in iOS to send/receive custom HEX data, other than working with services & characteristics?
Comment: Did you get solution to this, please share
Answer: No that is not possible, but the reason for this is not iOS but that the 'services' and 'characteristics' are just part of how the BLE protocol is defined.
Official spec:
https://developer.bluetooth.org/TechnologyOverview/Pages/BLE.aspx

Generic Attribute Profile
The latest Bluetooth specification uses a service-based architecture
  based on the attribute protocol (ATT). All communication in low energy
  takes place over the Generic Attribute Profile (GATT). An application
  or another profile uses the GATT profile so a client and server can
  interact in a structured way.
The server contains a number of
  attributes, and the GATT Profile defines how to use the Attribute
  Protocol to discover, read, write and obtain indications. These
  features support a service-based architecture. The services are used
  as defined in the profile specifications. GATT enables you to expose
  service and characteristics defined in the profile specification.
Comment: Your answer is incorrect: you can send data in BLE outside the GATT paradigm.
Answer: The other answer is accidentally right, but for the wrong reasons.
Of course it is possible in BLE to send any kind of data, not just GATT. It's just that iOS forces you to work with GATT. There are no iOS APIs for anything else. So, yes, it is iOS that prevents you from doing it.
If you wouldn't be forced to work with GATT, there would be some other options:

L2CAP Credit-Based Channels - you create a channel that allows you to send full 23 octets of data per packet (that's in BLE 4.0 and 4.1; 4.2 allows more than that), in whatever format you choose to.
With access to the HCI, you can send a custom ACL Data Packet to avoid the L2CAP header. But you need to also modify the other side to make sure it parses it correctly.
Answer: Yes you can send data over ble device. I've implemented already. By implementing peripheral object's writevalue method to send data on given characteristics of your ble devices. And also for getting data back from the BLE devices you could use peripheral object's readValue method. Data will be started in update delegate method of bluetooth framework


How to install mysql cluster?

Question: How to install Mysql Cluster 7.1 or 7.2 on Ubuntu 10.11 ?
On a fresh install of Ubuntu, we must uninstall pre-installed mysql before?
What is the best way, use .tar.gz on Mysql Website with or witout glibc or user apt-get install mysql-cluster-client-5.1 and mysql-cluster-server-5.1 ? I think that have a bug with these packages.. Please help. thx.
Comment: There is no such thing as 10.11 .. did you mean 11.10?
Answer: You can leave the regular MySQL installation in place if you like and then follow the instructions in the MySQL Cluster quick-start guide to install, configure and run MySQL Cluster from the tar ball.
Answer: Here is what you need to do to install a mySQL Cluster:

Go ahead and grab the latest package software from the source.
You will need to locate the package that you just downloaded (usually in the downloads file) and extract the files to a directory of your choosing.
In terminal (Ctrl+Alt+T) create a link to the extracted files (this will vary depending on where you extracted too. Should go something along the lines of tar xvf File Path/Filename.tar.gz && ln -s mysql-cluster-gpl-7.1.2-linux-x86_64-glibc23 mysqlc after the && you will need to know what package you downloaded to input the correct information.
You will need to initiate your mySQL management node, data nodes, and eventually your mySQL Server.

Its always best practice to place your cluster in the root of your directory to keep things simple, but its really up to you. Good luck!

How to install mysql cluster?


Accidentally delete ibdata1, ib_logfile1 and ib_logfile0

Question: Actually i have problems with the database always down due to log. Usually when I restart it will work just fine. But recently the database cannot start and make me think to simply delete those mention file. At first I thought it's ok after delete the files because mySql can run as usual but i just found out that I lost my wordpress database. Upon checking mysql admin console, I can see all the tables are there. But I cannot perform any queries on it. How do I get back those missing tables as well as the data.
Comment: The ibdata1 file contained the actual data. You will need to restore from a backup.
Comment: depends. there's a mode when innodb stores each table in separate files.
Answer: The ibdata files contain some of your InnoDB table data. Removing them has likely rendered the InnoDB data within your tables corrupt.
At this stage you should probably look into restoring a backup. Alternatively you could try to recover the data with extundelete, or similar tools for data recovery.
Answer: You should reach for your backups and restore from them. If you don't have backups then you could try undeleting the files but make a copy of the disk (using dd) and work on that.


Can a Linux install be moved from one computer to another?

Question: split to here
I have a 16gb flash drive which I want to contain a portable Linux install.  If I could just install Knoppix onto the flash drive, and have that work on any computer, I could do that.  Would that work, or are hardware specific things set when you install?
Comment: Might not help you, but I did similar to you, only not a live Linux distro but a regular one. I disabled swap to stop it killing the drive, and just created a NTFS partition.
Comment: @Mat, good point.  I split it and added a link to each question.
Answer: While "work on any computer" is a bit too broad, it is possible to build and configure a system so that it works on as many hardware configurations as possible — after all, that's what projects such as Knoppix try to do, have a kernel with lots of modules available and run clever startup scripts that try to tweak the configuration during the boot process.
Even if, in some cases, it may fail, it's possible to tweak some boot options to workaround known issues (again, that's what Knoppix does with its "cheatcodes", inserted at the isolinux prompt.
This said, even if it covers most cases, I'd still keep some way to exchange data, just in case you're unable to boot it in some computer.
(More technically, hardware-level settings are mostly when you configure the kernel. But many distros just ship the same binary kernel for all its users who prefer not to compile their own kernels. Some hardware-dependent logic may be also set in the configuration files, but that's not as drastic as lacking the correct kernel driver for some device — it will probably just boot but show some error.)
Comment: Have you ever tried moving an installed Linux OS from one physical computer to another?  I'll check out Knoppix, thanks.
Comment: I don't think I've ever moved an OS between two computers, but I've moved a Debian install to a virtual machine — it worked, but I had to recompile the kernel to add some VirtualBox (VB) modules and install the VB X Windows drivers. Maybe the default debian kernel supports VB, but I usually compile my own.
Comment: Ok, thanks.  I think I'll just set-up Knoppix as a live-USB.  I still have the problem of partitioning, but thank you for your help with this.


Game with computers choosing the worst possible moves

Question: Since chess engines in one way or an other rank alternative moves, it should be able to search for the worst move as well as the best. Have engines played each others trying to lose, and what has come out of that? Do they for instance set up for devastating tactics against themselves? (It might be a style of chess that I recognize...)
Comment: Are you talking about [loser chess](https://chess.stackexchange.com/questions/6501/has-loser-chess-been-solved), as that has been solved?
Answer: Yes. Chess engines can be reprogrammed to play a bad move. This is not very hard, just pointless and waste of time.
Some possibilities:

Choose the worst move statically without even going into search
Choose a move randomly from the move generator
For each legal move in the position, play it internally and the run a regular search. Choose the move that gives the worst score.
Reverse piece material sign, so that the engine would give away materials for free. For example, scoring +9 for giving away the queen without any compensation.
Similarly, play around the piece square table values.

A few years ago, someone made a chess engine Moron for exactly what you descrbe.

http://talkchess.com/forum/viewtopic.php?t=47026&highlight=julien+loser
Comment: But what if the opponent tries the same thing. And not according to some made up "loser chess rules", but just lose in ordinary chess. Why would it be harder to deliberately lose in chess than it is to win?
Comment: @LocalFluff I am not so sure I understand. Can you edit your question?


Have an older cat that lost her sister and now meows all the time, why?

Question: We adopted both cats from the shelter on the same day. The younger one was 1 year old or so and the other was closer to 2 years old the vet said.
We had them for 14 years and they really didn't play together at all with the one taking over and the other was okay with her doing that.
They rarely sat or laid next to one another and even rarer played together with the most being laying in wait then chase the other for a few minutes.
However we both work during the day and have no idea what they did while we were gone for 10-12 hours of the day.
After her sister passed 6 weeks ago now she has been constantly crying, we let her sit with us but she only sits with us for a few minutes then leaves still crying.
We don't know what to do at this point, we tried playing with her more but she just gets bored after a few seconds, we have tried feathers, laser lights, getting on the floor with her, etc. but after a few minutes she starts crying again.
We thought at first she was grieving but it's been 6 weeks and she hasn't let up at all.
She won't let us sleep and that's affecting our work now.
Any suggestions ? Not sure if she needs a new buddy or not as we've read that often that's not the solution.
Comment: Have you checked with your vet to rule out any medical reasons for the crying?
Comment: I think she misses the licking of her sister. She doesn't know, what is death. I don't think that a vet could do anything with it.
Comment: Did she see the body of the deceased sister? What were the circumstances?
Answer: Ahh! That was enough time which your cat has spent to its sister. And she was never alone! But now, as it's sister is dead, so she feels alone.
Try to give her a partner. Because she was living with her sister since long. So, it can change its attention and mood and to become normal again.
From other point of view, it can be psychic or mental issue for cat as well. A vet can help you to figure it out and also deal with it.
Hope this will help you!
Answer: If I were you I would play around with things cats know natively so that instinct will help with acceptance since cats lost more siblings in the wild than in domestication try triggering her instincts to socialize with other cats to hunt or just comfort with the occasional treat, brush or whatever she likes treat her like your own child and know what a child would go through.
Answer: Cats do not meow at other cats, generally, with the exception of kittens meowing at their mother.  It's a form of communication they only use with humans.  Therefore, she's definitely trying to communicate with you somehow, and not say, looking for her sister.
You might try taking your animal to the vet for a checkup.  Sometimes unusual meowing can be a sign of a medical issue.  At any rate, it certainly is a behavior change which may have been triggered by her sister's passing, but it also could be that the timing is coincidental, and there is actually a different cause.
It may also be the case that the cat is simply trying to get your attention.  Many cats enjoy simply the presence of a human or another animal, and will do things like follow you around the house just to be near you.  I've even heard of cats that seem to meow when they want to go somewhere, but also want their owner to come with them.  If this is the case, then inadvertently you're encouraging this behavior by trying to take care of her when she meows.  The best you can do then is try to ignore it, as long as you are certain she's not trying to communicate something else is wrong.
Comment: While I'm aware that you didn't invent this and there is a common acceptance that cats don't meow among themselves, I experience them meowing to each other daily. I have three cats and they work together. If there's a bird in the garden, one cat will call the other two (it's not a real "meow" but it's still vocal communication to the other cats). If I'm giving a treat and not all cats are present, they will meow until the other one appears (or shows no interest). One of them is incessantly playful, and will run around meowing until someone (mostly the other cats) comes to play with him.
Comment: i can confirm cats in the same house do call for each other and even siblings living in different houses can use vocalisations to greet each other even outside,when my older cat died my other younger cat did call for her(it was not the same sound as the cats use to comunicate with me)
Comment: While it's unclear why precisely your cats are meowing (who knows for sure what's going through their heads, so it may be at each other) people say they only meow at humans because if you take humans out of the equation entirely, like in a feral cat colony, the cats do not meow at each other. Therefore, I think it's a pretty reasonable conclusion that cats do not meow at each other.
Comment: I think you've missed my point slightly. My point was that a domesticated can learn to meow at other cats as well (even if that's learned through human contact and would not occur without human involvement), which means OP's cat could now be trying to communicate to the other cat.


$p$-adic Kato--Nakayama space

Question: Given a log scheme over $\mathbb{C}$ whose underlying scheme is locally of finite type, you can associate to it a ringed space called the Kato--Nakayama space. Is there a $p$-adic analogue of this construction (presumably something rigid-analytic)?
Comment: I believe many people have thought about this at some point. The answer so far is no. Of course there are the algebraic analogs of the Kato-Nakayama space: the (Kummer) etale site or the infinite root stack. The following paper of Andre https://arxiv.org/abs/1207.3380 is the only reference I know which tries to make an analog of the 'real oriented blowup' construction.
Comment: @PiotrAchinger you seem to be fairly informed about this stuff; if you made your comment an answer (maybe add some details if you wish), I would accept the answer (so this gets out of the unanswered queue).
Comment: I'm working on this :-)
Answer: I believe many people have thought about this at some point, and I don't think such a construction is known.
In the paper https://arxiv.org/abs/1207.3380 , Yves Andre considers the real blowups (in the complex plane) as a completion with respect to the "sectorial uniformity", and then considers some $p$-adic or non-archimedean variants. I am not sure if this produces a desired analog of the Kato-Nakayama space. Andre's point of view is applications to singularities of differential equations (especially irregular, i.e. worse than logarithmic poles), phenomena like overconvergence etc.
There are the algebraic analogs of the Kato-Nakayama space: the (Kummer) etale site or the infinite root stack, both equipped with a "proper" projection down to the underlying scheme, which in the log regular case are "homotopy equivalent" to the trivial locus of the log structure (in characteristic zero, or after prime to $p$ completion), and which over the complex numbers can be compared to the Kato-Nakayama space (see e.g. the paper of Carchedi-Scherotzke-Sybilla-Talpo).

$p$-adic Kato--Nakayama space


What is "denying" a creep?

Question: My friends and I play DOTA 2 and I always wonder how do they get richer and have more EXP than me even if I did not die and they already did.
They say something about "denied thing" but they never tell me. Can someone tell me how to deny a creep?
Comment: @MBorg I don't think this is a duplicate. That already assumes you know what denying is, while the OP doesn't appear to know the term.
Comment: I took the "Can someone tell me how to deny a creep?" as how to do it. But yes you're right, I think the OP is more on how to do it within the game instead of the action to do so. My mistake
Answer: EXP and gold you get in DOTA 2 come from landing the killing hit on an enemy, be it a player or one of the creeps, which are the minions heading towards your base. However, you ONLY get rewards from you or an ally landing the last, killing hit on an enemy mob. It doesn't matter if you did 95% of the damage yourself, only the last hit counts.
Because of that, players have come up with "denying" creeps, towers and sometimes even heroes, which is basically landing the killing hit on YOUR own minion, to deny the enemy the killing hit and associated rewards. A successful deny reduces the gold and EXP the enemy team gets to 30% EXP and no gold reward, and additionally rewards the denying player with 20% of the normal gold reward (but no EXP reward).
The DotA 2 wiki provides additional information on denying:
https://dota2.gamepedia.com/Denying
You can deny a creep, tower or hero by issuing an attack-move command directly onto the ally you want to deny. The default keybind for this is the A key.
Comment: Your answer is partially correct. Exp is always awarded, no matter who deals the killin blow. It is reduced in case of a deny, but it is not reduced when your allies strike the killing blow. Regarding gold, you are correct in most cases. Creeps only give gold to the player striking the finishing hit. But towers for example also grant gold to the rest of the team. And heroes grant gold to nearby allies. Towers and Heroes also can be denied (under certain circumstances), resulting in less/no gold (and xp) for the enemies.
Comment: I think it's worth mentioning that the deny rewards are changing with patches (recently it was extra exp for the denier, not gold), and briefly state conditions when denying is possible (<10% HP for towers, <50% HP for creeps, <25% and a special debuff for allies, several ways to suicide)

What is "denying" a creep?