Light and Gravity - bending of light around a massive body

Question: Well, as I have read, a massive body can cause light to bend around itself due to its gravitational attraction. What I don't understand is how, as the Newtonian formula for the force of gravitational attraction is $$F = \frac{Gm_1m_2}{r^2}.$$ As photons do not have (rest) mass, shouldn't there be no attraction between light and the celestial bodies, and therefore no bending? Surely I am missing a key point. Please point out my logical flaw?
Comment: As far as we know, the "right" theory of gravitation is General Relativity, not Newtonian gravity, and General Relativity predicts every body/particle bearing energy experiences gravitational effects, not just massive bodies, as it was in Newtonian gravity.
Comment: possible duplicate of [Why can lights(photons) bends in a curve through space without mass?](http://physics.stackexchange.com/q/107930/)
Answer: The flaw is that you are trying to mix classical with relativistic concepts.
Gravitational lensing (this is the phenomenon you are referring to) is best described in terms of general relativity. Massive bodies bend spacetime, inducing a curvature, which is described by Einstein's equations:
$$G_{\mu\nu}=8\pi T_{\mu\nu},$$
where on the left hand side is the Einstein tensor which contains information about curvature and on the right hand side there is the energy-momentum tensor, containing information about energy and matter. From this formalism, it is possible to derive so-called geodesics, which are the paths objects will take through curved spacetime.
Photons feel this curvature and have to move according to it, resulting in the phenomenon we see as "bending". Below, you can find a visualization of the effect:
Comment: "Massive bodies bend spacetime, inducing a curvature, which is described by Einstein's equations: $G_{\mu \nu} = 8\pi T_{\mu \nu}$, where on the left hand side is the Einstein tensor which contains information about curvature". This sentence is in direct contradiction  with this answer [here](http://physics.stackexchange.com/a/105736/43402): "So Einstein's equations in vacuum mean exactly that: $G_{\mu \nu} = 8\pi T_{\mu \nu} = 0$ in a region without mass-energy." Obviously, if $G_{\mu \nu}=0$ everywhere in vacuum (also around massive bodies), then it tells nothing about curvature.
Comment: @brightmagus You should read the next sentence in that answer as well. You have obviously misunderstood something.
Comment: Are you saying that zero 1 thousand kilometers from the surface of the Earth is different than the zero 1 thousand kilometers from the surface of the Sun?
Comment: "where on the left hand side is the Einstein tensor which contains information about curvature" clearly explains that it's not the Newtonian laws that can explain the bending.  I understand that "curvature of space" is some other term for Einstein's equations, which deviate from Newtonians equations - even (with that intricacy) if energy of photon, named relativistic mass, is put in for Newtonian mass that is subject to inertia and gravitation.
Answer: The situation is a little bit more complex. In cases of velocities approaching light speed, Newtonian mechanics doesn't really work.  Such situations require using the equations of special relativity. But, even considering special relativity effects is not sufficient to solve problems where gravity is also acting. Special relativity conditions in the presence of gravity can only be correctly handled by general relativity.
General relativity doesn't work by producing forces on point-like masses to generate acceleration. Rather, general relativity works on masses moving linearly in a curved spacetime. The linear movements on a curved spacetime are named "geodesics". Practically, it requires using very complex differential equations to compute the trajectory. As non-physicists we can imagine this as such:

Of course, you can calculate the bending of light as if it were mass points moving with light speed in a non-relativistic universe. But the calculation will not correspond with the experimental results.
Practically, the first experimental evidence confirming general relativity was that the bending of starlight by the sun's gravity was not as we calculate it by Newtonian Mechanics. The Einsteinian results differ around 50% from the Newtonian results, and with this the experiments are consistent.
Comment: I wonder what mass Newton had assumed for a photon of specific wavelength. - Did Einstein not assume much, but explain  and mathematically describe the empirical finding that light cannot be accelerated in speed but still can be bent, by applying his wisdom that energy can be equivalent to mass? As it occurs: Is "curvature" as word less misleading as the picture given above, as in fact there is discrepancy between "bending" of light and non-acceleration (speed). Don't fall for curvature...in your minds it should not be heavy, the light.
Answer: As others have said, general relativity is the right theory of gravity (as far as we know). But even in Newtonian gravity, we predict light bending. The thing is, for a photon of mass $m$ moving near the sun of mass $M$, it's true that $F=GMm/r^2$; but also for the photon $F=ma$. And what we care about is the acceleration of the photon, which is zero force divided by zero mass. So it's better to combine the two equations and get that for any object, its acceleration in the Sun's gravity is given by $a=GM/r^2$. This predicts light bending by the Sun.
Unfortunately, the amount of light bending it predicts turns out not to be the amount of light bending we observe (by looking at star positions during eclipses, and using radio interferometry). In fact, if you work it through with Einstein's theory of gravity, you find that light bends by exactly twice as much as Newton predicted - and this agrees with experiment. The extra bending comesabout because space is bent (distorting the geometry around the Sun), in addition to the bending of time into space that makes things (including light) fall.
Comment: if you really want to be precise, take the limit as $m$ goes to zero, then it works.
Comment: Is that mathematically sound, though? You're cancelling a factor of zero from each side.
Answer: Your logic is not flawed, you're simply using the wrong formulas. According to Newton's law of gravity
$$F = G \frac{m_1 m_2}{r^2}$$
only massive bodies feel the gravitational force and since the particles of light - photons - do not have any mass, they do not feel the gravitational force.
Einstein generalized the concept of gravity in a geometrical way, called general relativity. In general relativity, you cannot distinguish if you are in an accelerated reference frame or if you are under the influence of gravity. Basically, you cannot say, if you are in a resting elevator on earth or if you are in an accelerating elevator far away from any gravitationally interacting object. Since light would bend in an accelerating reference frame, it also has to bend due to gravity. See e.g. the picture here:

This is a famous consequence of general relativity. Shortly after the theory, the effect of bending photons was measured during a solar eclipse and this aspect of general relativity was confirmed. We should not forget, though, that Newton's law of gravity is still a very good approximation, but it cannot explain the bending of light particles, as you have correctly pointed out.
Comment: So if we can accelerate a rocket/elevator fast enough, we would see light bending downwards? A laser beam would bend downwards in an arc form? And one more question, if we take Einstein's general relativity, does Newton's 3rd law of motion still hold up? As the acceleration of the elevator is causing light to bend downwards, thus exerting a force on the photons, will the photons also exert an equal and opposite force on the elevator's acceleration? Will they cause the acceleration to reduce?
Comment: There is no force acting on the photons. They would travel in a straight way, but since we are in an accelerated reference frame, we would see the light bent (as in the right picture above).
Comment: Imagine yourself being in an elevator with a window. Outside the window, a friend of yours is standing. Now you are accelerated upwards. From your perception, in your reference frame, it looks like your friend is accelerated downwards, although there is no force acting on him. There is nothing strange here: It's just what you observe when you are in an accelerated reference frame.
Comment: So its a pseudo force? It doesn't really exist but we just see it? Strange though... Something that came to my mind: Shouldn't there be a certain acceleration/gravitational pull, that will cause light to start an orbital around itself?
Comment: If two are moved they may agree upon a third as a stationary who must be able to be looked upon.  Even in an elevator with no window some music might anounce that light is "no stapler".


Ability to edit a chatter post?

Question: Has anyone implemented anything custom in Chatter to allow for the "Edit" of a Chatter post on a feed rather just the standard delete function? Just looking for a quick and efficient way to implement that type of functionality without having to delete an entire post because of a misprint.
Comment: I think this is a really important use case as the Chatter platform matures. I would strongly encourage you to vote on this idea: https://success.salesforce.com/ideaView?id=08730000000kymHAAQ
Answer: From the idea:

While the ability to edit chatter posts came in Summer '15, it lacks the ability to edit chatter posts with links or files attached to it.

From the Spring `16 release notes: Edit Chatter Posts Containing Files or Links

So you wrote an awesome Chatter post and attached an even more awesome picture, but then you forgot to @mention your boss. Previously, you had to use comments to make any changes to Chatter posts that contained files or links. Now you can simply edit the original post. This feature is available in Salesforce Classic and the Napili template in Salesforce Communities.
Answer: No, it isn't possible to edit a Chatter post after it has been created. See the FeedItem documentation. Update is not a supported call.

Ability to edit a chatter post?


Electric field discontinuity

Question: When there is a charged spherical shell for example, I can calculate its charge using:
$$(\vec{E_{out}}-\vec{E_{in}})\cdot \hat{r} = \frac{\sigma}{\epsilon_0}$$
We generally ignore external electric field if it present because it cancels out, but what about if the spherical shell is inside a conductor? then $\vec{E_{out}}=0$ and we get something completely different - now the external field doesn't cancel. What have I done wrong?
Answer: Placing a charged spherical shell centered inside of an uncharged spherical conducting shell does not change the field at the surface of the charge. There will be an induced charge on each surface of the outer sphere.  If your charged sphere is in contact with the inner surface of the outer sphere, then its charge will appear to move to the outermost surface.

Electric field discontinuity


SPC vs Autoencoders in anomaly detection

Question: Considering the usage of Autoencoders in anomaly detection of time-series data, why SPCs (control charts) have lost their charm? Are there any advantages with Autoencoders and disadvantages with SPCs?
Answer: Control charts are widely used still (whether people know it or not). However it is limited to cases where it is possible to define meaningful and stable targets and bounds for a metric. The classical example is in manufacturing, when the intent is to produce items which has a certain property at a certain value. Like each cereal box produced should be 510 grams, 500 grams of net contents and 10 grams for the box. Being outside for example +-5% of this would be considered an anomaly.
However when there are no such clear metric, or targets, more advanced tools can be useful. For example consider you run a web service which serves webpages to users. Different time of day have different usage patterns. Different users make different kinds of request. Different kinds of requests have different impact on the system resources and thus the ability for your system to serve other (unrelated) requests. System performance will vary quite a lot, but a lot of it due to factors outside your control. And often it is not individual metrics which are the clue to "something" is wrong, but combinations of them.
This makes it hard define single-value metrics, and to set control-chart targets and limits. But an autoencoder can learn time-based patterns, the user-dependent patterns, request-type dependent patterns, and their relationships. And give an overall score for how anomalous the overall situation is.


In a multicore processor enviroment, can there be multiple threads running the same static method at the same given time

Question: I had read this question
Static method behavior in multi-threaded environment in java.
But this question didn't answer that can multi-thread running the same method at the same given time in a multicore processor enviroment.
If my title question is "yes", how exactly does my computer implement this? Since there is only one static method waiting to be called.
Do two cores respectively copy that static method to their ram of core and run them simultaneously and respectively?
I don't know if I express my point clearly. If not, I am more than willing to explain it. Thank you.
Comment: multicore or not, this is the same RAM. Answer to your question is the same as the one you're referring to.
Answer: All of the information required to execute a piece of code independently is stored locally in a thread. When a core executes a method it does so in the context of a thread. Since the actual executable code (the instructions) cannot be changed (it is not writeable), there is no need to copy it anywhere: it can just be shared between threads/cores.
Methods can have local variables. These are stored on the stack, which is a property of the thread. Each thread has a separate piece of memory for its stack, and so each core will be accessing different memory for local variables.
For data on the heap, this is shared, which is why you have to take care when accessing that in a multi-threaded environment by co-ordinating access (for example, by using synchronized).
Being static or not static is not relevant. In either case, there is only one copy of the code. A non-static method can have multiple instances of the object data (and so potentially different cores will be accessing different heap data, although not necessarily) and a static method accesses static data (which is shared, and you have to co-ordinate that).
A core may copy executable code to a local cache for execution, but this is done for performance reasons and not because of any issues with shareability.
Quick answer: yes.
Comment: Yes - the thread holds the context; that is, where you are in the code and the values of local variables in both static and instance methods. Everything else is on the heap. The only difference between static and instance methods is that an instance method can also access the members of an object whereas a static method cannot. It is confusing as instance methods look like they "exist" per object, but really the only thing that is exists in the object is the data. There is only one copy of the code.
Comment: It looks like I misunderstand what methods are,,, So, when a thread is created, it stores all context of a static method into itself. Then when that thread is executing that method, it justs run the context which has been already stored in itself??? Is that correct?
Answer: If you are talking about multithreading in single process then two threads will run a static method based on thread priority . But if you are talking about Multi Processor Multi Threading enviorment then Yes the same Static or non static method at the same given time can run in a multicore processor enviroment. Because each process will Run into Different JVM enviorment.
Answer: Short Answer, yes its possible.
Each method call will get its own stack and can run in parallel.
The static method to be called is just a set of executable statements. Since threads are not allowed to write to the method logic, each thread refers to the same set of instructions. It also has a pointer (sort of) which tells which line its executing from the instruction.
Think of it from a class/object perspective. All objects of same class share the same code base, but does that mean 2 objects cannot be created at the same time?
The instance refers to the same object but yet is different than another instance.
Same way, 2 method calls refer to same set of instructions, but differ in data ( which instruction they are on, what is the value of local variables etc).
I think your confusion is because the method is static (hence your assumption, only one copy). The copy remains the same, doesnt mean every time a method is called, instructions have to be copied. Differentiate between instruction and data, that will help.


Is using Compound as oracle dangerous?

Question: I'm really curious about this.
If I use Compound CToken function exchangeRateStored() as oracle for my project, is it dangerous? Can someone abuse that? Using flash loan to increase/decrease exchangeRateStored().
Answer: This is a great question - and there are multiple perspectives, so I will try and abstract away some suggestions into "principles".
Depending on usecase, one could argue that when it comes to oracles, "data quality" should be top of mind. When working with oracles, the question to ask is where are the sources of data, how reliable are they, how much coverage they have, what is the aggregation mechanic, risk of skew etc.  This ends up separating the issues out -- data generation can be left to off chain providers, and oracles focus on data delivery in a verifiable, tamper resistant way.
Using oracles as a data generation mechanism can be very complicated and open the oracle up to numerous attack surfaces that are common in the defi world, especially if there are "thinly traded"/"shallow" token pools that are susceptible to price manipulation that comes from massive market volume shifts etc.
Using oracles for data delivery is also prone to its issues, most of which can be defended against by having the oracles be decentralized as part of their security design which means that multiple independent oracle nodes have to report on, and aggregate, data before its submitted on chain. This helps make the data delivery piece manipulation resistant, and maintain high availability of the data. This would require that the data is sourced from multiple high quality data providers, and independently fetched, validated and aggregated by a network of decentralized oracles.
These meta principles aside, the way I read the exchangeRateStored() function is that it only uses data on compound and that means limited market coverage for the price of that assets across the market generally.  That is more subject to manipulation than multiple, aggregated sources of data.

Is using Compound as oracle dangerous?


text file - rows to colums using altova mapforce

Question: How can I convert a comma separated text file into a line separated text file using only Altova MapForce.
Is there a way I can put an 'enter' into the MapForce concat function?
Answer: When you add the Input as Text File there right click the input component and see the property. By default there is Comma for separation of values. Change the value. Other wise one more option is split the input text file.
[1] Here is link
[2] Book
Very important think for you there is nothing ready to eat in altova Mapforce.


How to find a counter example for non convexity?

Question: Consider a simple function $f(x,y)=\frac{x}{y}, x,y \in (0,1]$, the Hessian is not positive semi definite and hence it is a non convex function. However, when we plot the function using Matlab/Maxima, it "appears" convex. For the sake of clarity we want to find points which violate the definition of convexity, in other words identify the region (in the plot) where the function is non-convex. Can you suggest a procedure to do the same ?
Answer: The Hessian is $$\nabla^2 f(x) = \begin{bmatrix} 0 & -y^{-2} \\ -y^{-2} & 2xy^{-3} \end{bmatrix}=\frac{1}{y^3}\begin{bmatrix} 0 & -y \\ -y & 2x\end{bmatrix}.$$
For nonzero $y$, the determinant $-y^{-4}$ is strictly negative. This means that there must be exactly one positive eigenvalue and one negative eigenvalue. The function is nonconvex over the entire domain. Indeed, it is nonconvex at every point $(x,y)$, $y\neq 0$.
The function is affine for fixed $y$, and convex for fixed positive $x$. So it may be that when you look at the MATLAB plot you're seeing the convexity of these cross sections. At any given point, however, it is actually concave along the direction defined by the eigenvector corresponding to the negative eigenvalue.
I cannot tell you how many people I have encountered that insist that this function is convex for positive $y$! Good for you for not falling into that trap.
EDIT: That suggests a way to graphically demonstrate non-convexity, by the way. Pick a point, say $x$, and find the negative eigenvector, $v$, or at least a vector satisfying $v^T\nabla^2f(x) v<0$. Plot the function $g(t)=f(x+tv)$. It will be concave, probably visually so, at $t=0$.
EDIT 2: Here you go: $x=0.25+t$, $y=0.75\pm t$:
Comment: So actually no function $f(x,y)=x g(y)$ may be convex (given $g'(y) \neq 0$). Interesting. Thank you for the plot!
Comment: Thanks a lot for the plot and the procedure to graphically demonstrate the non convexity.
Answer: I think if you only look at one quadrant of $f(x)=\frac{x}{y}$ then it appears to be convex but if you look at all the quadrants then you should see that its non-convex.
Comment: Thanks for the response, but I am not sure what you mean by all the quadrants. The domain of the function is $x,y \in (o,1]$, which is the first quadrant.
Answer: If you write down the Hessian matrix you'll see that for $x,y\in (0,1]$ the Hessian is indeed positive semi-definite. This is call conditional positive semi-definiteness. You can see the Hessian as a matrix parametrized by $x$ and $y$: it is positive semi-definite depending on their values. Try to compute the eigen-values as a function of $x$ and $y$.
Comment: The Hessian is not conditional positive semi-definite. The determinant of the Hessian is $\frac{-1}{y^4}$.


kdiff3 for Buster

Question: The kdiff3 on Stretch worked okay, but the new version on Buster crashes, says it cannot scan files, etc and does not work for me.
Is there an alternative to kdiff3 for comparing large directory trees and seeing file content differences for Buster?
Comment: Have you looked at meld? This may also give you some idea of what is available https://alternativeto.net/software/kdiff3/.
Comment: Thanks; That was all I needed. I was disappointed to see Buster's kdiff3 version after using kdiff3 for years on multiple platforms. Some progress is not progress.
Answer: Installation of both file/folder comparison programs worked fine with Raspberry Pi OS Bullseye version 11, using:
<code>$ sudo apt install meld

$ sudo apt install kdiff*
</code>

kdiff3 for Buster


Sum of digits flaw name request

Question: Let's say I am making an encryption algorithm, and in the algorithm in have the following step: "multiply the integer from the previous step by 9 and take the sum of the digits of the resulting number."  By doing this, I've guaranteed that the result will be divisible by 9 in base 10, which let's say I did not expect.  My question is:  What is this error called, if it is an error?  Is this a specific case of a general class of flaws in crypto algorithms?
Answer: It depends completely on the algorithm if it would matter that the result would be divisible. If it was a cryptographic error I don't think it would have a specific name. Possibly a side effect or unexpected property.

Sum of digits flaw name request


Why does my gun reload slowly sometimes even with Quick Eject Mag?

Question: Sometimes when I reload, it's nice and quick, but the majority of the time, it's as slow as not having a Quick Eject Mag. Is taking damage the cause of the problem, or does it depend on if it's night and maybe I'm tired (although I'm not playing Survival and as far as I know none of the mods I have installed would slow down the reload speed)?
Comment: http://fallout.wikia.com/wiki/Quick_Hands check the bug section, could this be your issue?
Comment: There isn't a lot of information here to go on, but it's likely there is something else going on here: Pretty much everything in Fallout 4 is tied to FPS. It's very possible that you're hitting low FPS when you're trying to reload in combat which is causing it to seem like it takes longer to reload. Do you notice your guns reloading quicker when out of combat?
Comment: are you talking about reloading a magazine of after firing a shot?
Comment: One shot or multiple.
Comment: I think you are confusing reload speed with fire rate. Reload speed is when you reload your clip, fire rate is the time between 2 shots. Rifles have a low fire rate and the time between shots can be 1-2 seconds, automatic guns have a high fire rate to pop out as many bullets as they can in a short time.
Comment: No, no, I'm talking about why reloading takes so long. I know the fire rate is slow, but I can tell when the gun reloads at the speed it should and when it's slower than it should be.
Answer: There is not a lot of information on the quick eject mag, but the effects are comparable to the Quick Hands perk.
If you look at the Quick Hands Wikia page there is a glitch that prevents it from working, occurring most frequently after entering or exiting Power Armor. Changing weapons seems to resolve the issue. It is possible the same glitch occurs while using the quick eject mag.
Other things to note is that neither the weapon mod nor the perk does not affect the time it takes to cycle the bolt on a bolt-action weapons such as the hunting rifle or pipe rifle. It only effects reload time. The bolt cycle time falls under the rate of fire category.
Almost all weapon animations are tied to the frame rate in Fallout 4. During moments of intense combat or explosions your frame rate may drop which will also affect the reload speed of your weapon (and rate of fire, and swing speed of melee weapons).
Lastly, some weapons have different and longer animations when reloading from an empty magazine than a partially depleted magazine. When reloading from a completely empty magazine your character may spend an extra moment chambering the first bullet into the gun's receiver. This is not necessary for a weapon that has more than one bullet left in the magazine


Charge AGM battery from car alternator

Question: What is the most efficient way of charging an AGM battery using a car alternator? I have a 12V plug connected to alligator clips which can be used in the 12V sockets inside the vehicle. Is this the best option or is it best to use jump start cables to connect directly from car battery to AGM terminals (positive to positive and negative to negative)? How many amps of current would be achieved with each of these methods?
Answer: I would connect the battery to the vehicle battery with the jumper cables, assuming that the battery is a similar capacity, then start and run the engine at about 2000rpm.
If you use the 12v sockets you risk blowing a fuse or damaging something.
Answer: 13.8V could be an absolute voltage limit.
AGM cells are more fussy about reliable charging vs temperature and have a reduced float voltage to prevent grid corrosion, gassing and water loss.
Therefore at room temp do not exceed 13.6V and reduce to 13.4 on float.
Jumper cables to battery on low idle should achieve this. (e.g. 1000 RPM depending on vehicle)  Higher RPM may  rise to 14.2 and hopefully, not much more, yet this should be avoided for AGM batteries.
If you plan on doing this often, I would use a current shunt of the jumper cable and measure voltage drop on the wire, but not at any connection points (Kelvin method) with a mV DMM calibrated from an ammeter.
https://batteryuniversity.com/index.php/learn/article/charging_the_lead_acid_battery
Since AGM cells reduce in ESR with rising temperature and also reduce in cell voltage, thus the max current rises from a fixed voltage regulator. This is why temp-compensation is necessary over a wide ambient temp. If over-voltage occurs with high current, the temperature rise can exceed unity gain for heat rise vs heat reduction from reaching full charge and result in thermal runaway and catastrophic failure.  (e.g. excess H2 in a sealed box is explosive with O2 and spark or the battery acid over-heats)
DIY
You could put a long wire or resistance heater in series to limit current and monitor voltage manually or use a proper charger.
Comment: The alternator on my car (a 2016 Honda Civic LX) puts out 14.5 V regardless of the RPM, according to the voltmeter I installed. Is my car weird?
Comment: If the voltage is between 13 and 14.5 volts, then your alternator is probably fine.  Higher than 14.2 reduces sulfation to increase lifespan from high ESR due to elevated ambient temp. but also increases acid evaporation which shortens lifespan, so it depends on ambient.  (-2mV/'C) It also depends on AGM, SLA vs. flooded acid, **flooded acid tolerates a higher voltage of 14.5 while AGM does not!**  @TannerSwett

Charge AGM battery from car alternator


Server 2008 R2 not visible in DPM 2007

Question: I have a Dell PowerVault DP600 running Data Protection Manager 2007 on a Windows Storage Server 2003 R2 OS.  The unit was delivered by Dell in this configuration.  It has worked wonderfully for years, backing up XP, Win 2003, and Win 2008 servers.  I have recently added a Dell PowerEdge T710 server running Win2008 R2 functioning as a file server.  The DPM can't see this machine in Active Directory to deploy an agent. The agent was manually installed on the new server by mapping the DPM server's C:\ and installing from the DPM server without error. The new server is still not listed in the DPM. Is there something else that needs to be checked for the server to get listed in DPM?
Answer: I remember at one point in time there was a specific service pack or update required to get 2007 to work with 2008 R2 and Windows 7 boxes.  I'll see if I can find the link but make sure your DPM box is fully patched.
Comment: The DPM server and DPM software is fully patched from what MS update provides. If there's some hotfix that isn't listed you can find I'll check it out and see if it help. Thanks!
Answer: Applying the hotfix from here fixed the problem. I'm not sure excactly what the problem was to cause this, as the description of the issues in didn't describe what was happening.

Server 2008 R2 not visible in DPM 2007


Why do I need MVVM for WPF/Silverlight, is there any good reason one cant use MVC?

Question: Maybe I'm crazy, but I get MVC. It makes sense. MVVM seems like a way to make MVC harder, am I wrong (if so, why?)?
Answer: Maybe this is helpful.
Answer: You don't need MVVM - it just works well.
MVVM is just an alternative.  You are free to use MVC.  MVVM just takes advantage of some specific features in WPF and Silverlight (mainly the amazing DataBinding support, but also templating and commanding) in order to make your life, as a developer, simpler.  MVVM is particularly good as decoupling the View from the code - even more so than MVC, as using the DataBinding allows a designer to change the View much more effectively without worrying about code changes than MVC.
MVVM also has the benefit of being very closely related to the fundamental design principles behind WPF and Silverlight.  The basic idea of MVVM is very similar to the design of WPF and Silverlight at a fairly low level - For example, look at how templating works with custom controls, and compare it to the View/ViewModel separation, and there are a lot of correlations that can be drawn.
Answer: I think that if you get MVC, then MVVM is really the same - with 1 additional part (the ViewModel).  The reason that MVVM is more useful in my opinion has to do with the new DataBinding processes.  The ViewModel provides useful abstraction and clarity about what is being databound, and how that binding is presented or converted.  That's all it does in my mind.
The missing part from MVC is actually in the MVVM pattern, it's just the hidden part of MVVM in my opinion.  If you look at most MVVM frameworks, most provide some sort of messaging or notification system, which really provides the missing Controller aspect of MVC.
Think of the ViewModel as the code-behind for your View, the View as the Designer of your View, the Model as the Model, and the Notification / Messaging system as the Controller, and we have a truely equivalent pattern.
This was a struggle for me to understand as well (I came from the MVC pattern as well, but now love the MVVM pattern).


landscape client registration

Question: looking for some guidance for landscape client config. I just rebuilt LDS server and re-registered clients. One client keeps sending authorization requests even after I accepted it. I tried restarting client, rejecting duplicates - does not work. I compared client config with other client - all the same. Has anyone seen this behavior before? Any advice is appreciated.
Answer: Try to fully unregister and re-register.
<code>sudo apt-get uninstall landscape-client
sudo mv /var/lib/landscape /var/lib/landscape.old
# Remove any duplicate computer in LDS UI
sudo apt-get install landscape-client
# attempt to re-register anew.
</code>
I know you have probably done something similar, but the /var/lib/landscape part you may have not known about.
Comment: Hi dpb! Thank you for your comment, it did help. BTW, I did this procedure but did not rename '/var/lib/landscape' folder, I guess it was the key! Thanks again and have a good weekend, joe

landscape client registration


When calculating the specific heat capacity of a solution, would the specific heat capacity of the copper calorimeter used affect the final results?

Question: I experimentally calculated the specific heat capacities of solutions by heating them in a copper calorimeter- will I need to take the specific heat capacity of copper into account during my calculations?
Answer: Yes because a copper calorimeter might have a significant thermal capacity ie heat is required to raise its temperature.
More recently materials like polystyrene are used for the containing vessel as polystyrene has a low specific heat capacity and also is a comparatively good insulator.


How does phenomenology deal with time-consciousness?

Question: How does the strict phenomenologist deal with atypical forms of consciousness that an analytical philosopher need only point to brain function to explain? For instance, how does phenomenology deal with the problem of sleeping, because discontinuity of awareness seems problematic?
Comment: Hello, AnduinWilde. I think I restated your question a little more clearly. Welcome to SE Philosophy, and thanks for contributing with a question/response! If you haven't done so, please take a quick moment to take the tour. https://philosophy.stackexchange.com/tour More specifics can be found in the help center. https://philosophy.stackexchange.com/help
Comment: I get the feeling you are referring to a very specific text or concept, although you chose to omit it in your question. Without this context your question seems incomplete.
Comment: Reference on this topic: Dan Zahavi. Many articles and an excellent introduction to Husserl's Phenomenology ( with a chapter on the subject of time consciousness).
Comment: Note: it could be questionned whether there is no cosciousness when we sleep. (1) when I dream I am somewhat aware, I have experiences (2) maybe, as Descartes says, what lacks during sleeping is reflection on our thoughts , not thoughts themselves, and it is this absence of reflection that prevents us from remembering our sleeping thoughts.
Comment: See [On Birth, Death, and Sleep in Husserl's Late Manuscripts on Time by Geniusas](https://link.springer.com/chapter/10.1007/978-90-481-8766-9_4) and Levy's thesis [Phenomenology and sleep](http://sro.sussex.ac.uk/id/eprint/65659/) for an approach more focused on Heidegger and Levinas.
Comment: I read part of Phenomenology and sleep,Husserl's meaning is Remberance fill in the gap for the sleep problem of the TIME-CONSIOUSness and there is still consciousness when sleepy.?
Answer: SHORT ANSWER
Phenomenologists redefine consciousness to include the past, present, and future as subject to its inspection. Therefore, sleep, which may lead to an interruption of perception doesn't lead to an interruption of consciousness per se.

Long Answer
A good introduction to phenomenology and time-consciousness can be found at the Internet Encyclopedia of Philosophy. Edmund Husserl is considered the founder of phenomenology, but there are many later philosophers in the tradition such as Martin Heidegger, Jean-Paul Sartre, Maurice Merleau-Ponty, and Jacques Derrida,
The question you have asked is an excellent question. Husserl who considered awareness an "intentional" activity had similar concerns:

[T]ime-consciousness underscores... other intentional acts because these other intentional acts presuppose or include the consciousness of internal time. For this and other reasons, Husserl, in his On the Phenomenology of the Consciousness of Internal Time (1893-1917) (1991), deemed time-consciousness the most "important and difficult of all phenomenological problems"

The short version is he rejected the idea of Newtonian time as fundamental, that is, to define consciousness in such a way that it needn't account for a sequence of discrete moments in the classical physicalist sense, but rather extend consciousness over the past, present, and future. Hence, for a phenomenologist, consciousness is broadened to include past in order to create a unity of temporal experience. From the article:

Husserl attempts to argue that consciousness extends to capture past moments of experience and temporal objects therein by "retaining" and "protending" the elapsed and yet to come phases of its experience and thereby the past words that do not presently exist.
Comment: For Eugen Fink, in his appendix written for Husserl's crisis, he says it is naive to criticize that phenomenology gives prority to consciousness over unconsicousness and reduces unconsicousness to consicousness, because the criticization postulates that we already know what "unconsicousness" and "consicousness" are, and only when we apprend consciousness could we ask questions about unconsicousness.
Comment: @AnduinWilde I find that fascinating but not out of alignment of expanding the definition of cognition in more traditionally analytical terms. If our consciousness is embodied, or perhaps even disembodied and extended to our tools and our society, why not de-emphasize the role of consciousness too. Thanks for the comment!

How does phenomenology deal with time-consciousness？


Terminology: arbitrary vs. finite

Question: How is arbitrary different from finite in mathematics? An arbitrary union of subsets and a finite union of subsets look the same to me! Is an infinite union of subsets arbitrary?
Comment: Arbitrary unions include both finite unions and infinite unions.
Comment: It's probably helpful to note that usually countable is stuck in between.
Answer: The meaning is totally different.  The statement "for arbitrary $x$" means "for all $x$", whereas "finite" is a term that can be applied to a set to indicate that its cardinality (size) is a natural number.
In particular, asking "is $A$ arbitrary" only makes sense in certain contexts, where you may be asking whether something is being proved for all $A$, or only for a specific $A$.
Sometimes the phrase "arbitrary union" is used as shorthand for "union of a collection of arbitrary cardinality" as opposed to "union of a finite collection" or as opposed to "union of a pair" (binary union.)
Answer: The word "arbitrary" does not specify a property of the thing it applies to. It is merely a rhetorical way to call attention to the fact that what you say is not restricted to things with any particular property.
It's still left to the reader to figure out from context what the thing you're calling attention to not saying is, but that is okay, because the word "arbitrary" has no formal effect.
So saying that "such-and-such is true for arbitrary unions" formally means neither more nor less than saying that "such-and-such is true for unions", period.
When we say "let $A$ be an arbitrary widget", we're not formally saying anything different from "let $A$ be a widget" -- just making sure that the reader notices that the only thing we know about $A$ is its widgetness. We can follow up with "remember that $A$ was arbitrary ..." which again just mean "remember that we didn't assume anything in particular about $A$".
Answer: Just to add to what Aloizio and Trevor have said -
Suppose I say "let $U$ be an arbitrary subset of the real line."  Then $U$ can be anything.  Some choices:

$U=$ all reals
$U=$ all rationals
$U=$ all irrationals
$U=$ all numbers greater than $\sqrt{2}$
$U=$ all even integers
or perhaps $U=$ just the set $\{1,2,3,4,19\}$
or anything else you can dream up.

Suppose I say "let $U$ be a finite subset of the real line." Now that means $U$ must only have a finite number of elements.  Of the above choices, the only one that still qualifies is $U=\{1,2,3,4,19\}$.
Answer: Arbitrary means you can have any indexed union of sets.
Finite means you can have only a finite union, i.e., you can only have an union indexed by a set of same cardinality of $I_n$, where $I_n:=\{1,...,n\}$
For example:
Define $A_{\alpha}:=[\frac{1}{\alpha}, 1]$ for every $\alpha \in [1, \infty)$
You can make $\displaystyle \bigcup _{\alpha \in[1,\infty]} A_{\alpha}$, and it will be a good exercise for you to show that this is $(0,1]$
Comment: Just an observation... my answer was heavily induced by the use of "arbitrary" in the context you mentioned especifically. My colleagues' answers are far more general and will answer your question more thoroughly.
Comment: Are you sure that's a union (the exercise)? Because $A_1=\left[1,1\right]$.
Comment: I think that that's an intersection. Here is my attempt at proof: $$\bigcap_{\alpha=1}^{\infty}A_\alpha=\lim_{\alpha \to \infty}A_\alpha=\left (0,1\right ]$$
Comment: It is a union.
Be careful with some things and "sweeping generalizations". First, why is the first equality you use true? (Important observation: that notation you used in the intersection is usually used for countable intersection, which is not the case). Second, what even means that $\displaystyle \lim _{\alpha \rightarrow \infty} A_{\alpha}$?

Now back, to prove my statement, you must prove that:
**(1)** $\displaystyle (0,1] \subset \bigcup _{\alpha \in [1,\infty)} A_{\alpha}$

and

**(2)** $\displaystyle \bigcup _{\alpha \in [1,\infty)} A_{\alpha} (0,1] \subset (0,1]$
Comment: I'll do **(1)** as an example: $\displaystyle x \in (0,1] \Rightarrow 01 ~~~~~~~~~~$

$\displaystyle \frac{2}{x}>1 \Rightarrow \frac{2}{x} \in [1,\infty)~~~~~~~~$

$\displaystyle  A_{\frac{2}{x}}=[\frac{x}{2}, 1]$

Therefore, $\displaystyle x \in A_{\frac{2}{x}}$, and then we have that $\displaystyle x \in \bigcup _{\alpha \in [1,\infty)} A_{\alpha}$

Terminology: arbitrary vs. finite


What are mirror sites used for?

Question: I've heard the term mirror site being used for downloading packages, but I'm not exactly sure of its importance. Isn't a mirror site just a copy of another website?
Comment: [http://en.wikipedia.org/wiki/Mirror_(computing)](http://en.wikipedia.org/wiki/Mirror_(computing)). Also, this is off-topic for Superuser since it doesn't concern computer hardware or software (see the [FAQ](http://superuser.com/faq) for more information).
Comment: Nothing should be off topic. If some one has more knowledge than other, it is for sharing the knowledge. Not properly directing is a problem but over period of time it gets solved. You do not know how old is the person seeking answer.
Comment: @C2940680 I don't see what the OP's age has to do with anything. But at any rate, the FAQ defines which questions are acceptable on SU and which aren't.
Answer: Exactly. A mirror is there to balance the load (traffic) among many servers and to provide redundancy. If one server breaks down temporarily, the others will still be there and happy to server your content.
Comment: Also, mirrors allow you to download from a server that is closer to you than the master server, which can speed things up. And having mirrors in many countries makes it harder to shut you down, if you are running a kind of site that annoys people with expensive lawyers.
Comment: Kind of forgot this, thanks for the addition even though the question got closed :)

What are mirror sites used for?


SQL SERVER bulk insert ignore deformed lines

Question: I have to import SAP unconvered lists. These reports look quite ugly and are not that well suited for automated processing. However there is no other option. The data is borderd around minus and pipe symbols similar to the following example:
02.07.2012
--------------------
Report name
--------------------
|Header1 |Header2  |
|Value 11|Value1 2 |
|Value 21|Value2 2 |
--------------------

I use a format file and a statement like the following:
SELECT Header1, Header2
FROM  OPENROWSET(BULK  'report.txt',
FORMATFILE='formatfile_report.xml'  ,
errorfile='rejects.txt',
firstrOW = 2,
maxerrors = 100 ) as report

Unfortunately I receive the follwing error code:
Msg 4832, Level 16, State 1, Line 1
Bulk load: An unexpected end of file was encountered in the data file.
Msg 7399, Level 16, State 1, Line 1
The OLE DB provider "BULK" for linked server "(null)" reported an error. The provider did not give any information about the error.
Msg 7330, Level 16, State 2, Line 1
Cannot fetch a row from OLE DB provider "BULK" for linked server "(null)".

The rejects txt file contains the last row from the file with just minuses in it. The rejects.txt.Error.Txt documents:
Row 21550 File Offset 3383848 ErrorFile Offset 0 - HRESULT 0x80004005

The culprit that raises the error is obviously the very last row that does not conform to the format as declared in the format file. However the ugly header does not cause much problems (at least the one at the very top).
Although I defined the maxerror attribute that very one deformed line kills the whole operation. If I manually delete the last line containing all that minuses (-) everything works fine. Since that import shall run frequently and particularly unattended that extra post-treatment is not serious solution.
Can anyone help me to get sql server to be less picky and susceptible respectively. It is good that it documents the lines that couldn't be loaded but why does it abort the whole operation? And further after one execution of a statement that caused the creation of the reject.txt no other (or the same) statement can be executed before the txt file gets deleted manually:
Msg 4861, Level 16, State 1, Line 1
Cannot bulk load because the file "rejects.txt" could not be opened. Operating system error code 80(The file exists.).
Msg 4861, Level 16, State 1, Line 1
Cannot bulk load because the file "rejects.txt.Error.Txt" could not be opened. Operating system error code 80(The file exists.).

I think that is weird behavior. Please help me to suppress it.
EDIT - FOLLOWUP:
Here is the format file I use:
<?xml version="1.0"?>
<BCPFORMAT xmlns="http://schemas.microsoft.com/sqlserver/2004/bulkload/format"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
 <RECORD>
   <FIELD ID="EMPTY" xsi:type="CharTerm" TERMINATOR="|" MAX_LENGTH="100"/>
   <FIELD ID="HEADER1" xsi:type="CharTerm" TERMINATOR="|" MAX_LENGTH="100"/>
   <FIELD ID="HEADER2" xsi:type="CharTerm" TERMINATOR="|\r\n" MAX_LENGTH="100"/>
 </RECORD>
 <ROW>
   <COLUMN SOURCE="HEADER1" NAME="HEADER2" xsi:type="SQLNVARCHAR"/>
   <COLUMN SOURCE="HEADER2" NAME="HEADER2" xsi:type="SQLNVARCHAR"/>
 </ROW>
 </BCPFORMAT>

Comment: I found a much better support when I use format file with fixed column width (CharFixed instead of CharTerm). Then you can check some columns for expected content in the where clause. However, since SAP varies the column width  this is not an option in my use case.
Comment: Sad to see that it seems true that SQL Server is just not able to handle a row that doesn't 100% comply to the provided format. Why can't it just ignore and log the row and then continue instead of aborting the whole import immediately. Even worse, a kind of a error file is created and as long that one is present (not deleted by user or external program) no further import can be started! Isn't that strange behavior of professional software?
Answer: BULK INSERT is notoriously fiddly and unhelpful when it comes to handling data that doesn't meet the specifications provided.
I haven't done a lot of work with format files, but one thing you might want to consider as a replacement is using BULK INSERT to drop each line of the file into a temporary staging table with a single nvarchar(max) column.
This lets you get your data into SQL for further examination, and then you can use the various string manipulation functions to break it down into the data you want to finally insert.
Comment: SQL is actually really handy, but I think it focuses more on internal data handling and leaves the programmer to develop their own interfaces for data import and export.
Comment: Thank you for your input. Actually I have to agree that sql server bulk import is not very sophisticated. And not just import but also conversion of data is cruel. What a shame for such a commercial product.
Anyway, that trick with a one column temp table seems to be a kind of common practice. A Colleague had told me the very same thing.
I hesitate to do so though, since I'm afraid of negative performance impacts!
Comment: I don't have a lot of metrics about preprocessing `BULK INSERT` like this. If it's just the one line at the end of file that's causing the issue, you might want to think about making a small console utility to look for that final line in the file and trim it out. That way you have something you can wrap up into the automated upload process.
Comment: This is actually pretty much what I ended up doing. Not very charming though! All that trouble just due to insufficiencies of both programs, SAP as well as SQL Server. I'm wondering which product is worse? (I personally would vote for SAP.)
Answer: I was in the same trouble, but using bcp command line the problem was solved, its simply dont take the last row
Comment: Hi, welcome to stackoverflow. Please describe the answers more. Clear answer will help people understand what you mean and will increase the chance of selecting as an answer
Answer: I had the same problem. I had a file with 115 billions of rows so manually deleting the last row was not an option, as I couldn't even open the file manually, as it was too big.
Instead of using BULK INSERT command, I used the bcp command, which looks like this:
(Open a DOS cmd in administrator then write)
bcp DatabaseName.dbo.TableNameToInsertIn in C:\Documents\FileNameToImport.dat -S ServerName -U UserName -P PassWord

It's about the same speed as bulk insert as far as I can tell (took me only 12 minutes to import my data). When looking at activity monitor, I can see a bulk insert, so I guess that it logs the same way when the database is in bulk recovery mode.


How do people preserve wines, champagne?

Question: How do people preserve wines and champagnes for decades? Is there a special method or is it like keep in wine storage or cupboard and forget for some decades to be better in taste?
Comment: The question should be how do people age wines, not preserve. You cannot preserve a wine indefinitely. All you can do is slow down the agin process...
Answer: This really depends on the drink itself. Some wines are meant to keep for years. Others should be drunk immediately. Most should be drunk within 1 or 2 years. So choose your wine carefully. There are various vintage wine guides online.
That said, once you have chosen a wine meant for ageing, you do want a cellar (or if that is not available, a refrigerator designed for the purpose) that will be able to give you consistent:

Temperature: around 12-13 C (55 F)
Humidity: around 70 percent
Light: keep wines out of sunlight or even bright lights

And if the bottles have cork stoppers, they need to be stored on their side to prevent the cork drying out. This isn't an issue with screw tops.
And that's pretty much it. If you don't have a cooler or cellar, keeping them in a cool, dark cupboard is still going to help...
Answer: I did a deep dive into Stack Exchange because I thought this question would've been asked before! But, it has not. That doesn't mean that the answer isn't super easy to find.
First of all, not all wines are meant to be aged. The vast majority of wines are meant to consume when you pick them up at the store. How can you tell which are which? Mainly on price (although not always the case). As the price point goes higher, these wines have been made with aging in mind and many times are unpalatable at a younger age. Red wines are meant to age longer because the tannins (the thing that gives red wine it's color) are an anti-oxidant. Some white wines like Riesling can age for decades. Champagnes can age for a long time, but because of their delicate nature and the cork and the whole CO2 pressure thing, they are harder to age. I've had some nicely aged Champagnes.
So basically, keep it in the dark and as close to freezing as possible. Some say that 55F is the best temperature, but actually the closer to freezing you get makes it keep longer. The problem is that for bottles with corks you should have a relatively high humidity so the corks don't dry out.
The myth that wines with screw caps don't age has been debunked by the Australian wine industry because the have mostly moved to screw caps and the wines age just fine if differently than bottles with corks.
Aging of Wine from Wikipedia pretty much tells you the whole story.


How to set Value per token?

Question: how the Smart contract decide how much token need to be send on every 1 Ethereum ? didn't found any  which define such function, anyone ?
Answer: You need to specify the price of your token. Then when you are selling tokens in exchange for ether you divide the amount of ether by the price of each token. However, take into consideration that solidity does not have a representation of float numbers so 10/3 is 3, not 3.333333. To have a decimal representation you define how many decimal points you want and multiply your values by 10**decimal.
Here an example:
contract MyToken{
    uint public price;
    uint public decimals;
    uint mult_dec;
    mapping (address => uint) public balanceOf;

    function MyToken() public {
        price = 100000000000000000; //price in wei 1 Token = 0.1ETH
        decimals = 18;
        mult_dec = 10**decimals;
    }

    // people buy by sending ether to your contract
    function buyTokens() public payable{
        var amount = msg.value.mul(mult_dec).div(price);
        // do the other stuff here, i,e. update balances
    }
}

Remember that the balances are then multiplied by 10**decimals. If you use mist and you "watch" the contract defining decimals, mist will show the correct number of tokens.
I hope this helps

How to set Value per token?


Set as default master page in Sharepoint Designer 2010 does not change site at all

Question: When I open a site in SPD2010, and right-click a master page and choose "Set as default master page", it does not change the site at all.  Shouldn't it do that?
Comment: I am having the same issue! Checked in and all settings are good seemingly. I am site collection admin and no change to site at all when I set the custom master page to be the site master page. Probably need to set it to custom in SD AND then set it as the Site Master page. SharePoint is quirkier like that. Coming to hate all the stupid little nuances of this software.
Answer: In SPD, From the ribbon, in the Actions group you can click either Set as Default or Set as Custom.
These options correspond to the System and Site Master Pages, respectively.
So, make sure your changes in master page are checked in and published and select "Set As Custom" from ribbon
Also, since you are using Publishing site template, you can click Site Actions -> Site Settings, and then under Look and Feel, click Master page. Here you can change both system as well as site master page.
Answer: It depends if the masterpage contains different content and can show a difference. When you did change the masterpage make sure you save it before setting it as default masterpage.
You can test this easily bij copying the v4.master, change the copied file, e.g. add some text in PlaceHolderSiteName, save the masterpage and set as default. Now you have to see the text added to the site title.
Comment: Hi - thank you for your reply.  I took a copy of the nightanddaymaster, added some navigation at the top, and set it to be the default master page from within SPD 2010.  In the site I see that the System Master page is changed, but not the Site Master page. I am using a publishing portal.
Comment: Does anyone have any idea why, in SPD2010, "Set as default master page" changes the System Master page but not the Site Master page? I am using a publishing portal.
Comment: bumping this...
Answer: Have you checked in the file? Any non-admin user won't see any changes until the masterpage is checked in and published to a major version (i.e. 1.0, 20.0 etc.)


macOS Sierra USB Issues

Question: Has anyone faced any issues with the external hard drives or pen-drives not being detected on a MacBook that has been upgraded to macOS Sierra 10.12?
Comment: Someone probably faced some issues with external drives connected to the USB interface. But answering "Yes" or "No" won't help you much. So better open Console.app and search for USB/drive related issues in the various log files and post the errors! You may have to initiate the errors by attaching the drives and watch the log at the same time.
Answer: I own a brand new MacBook Pro 2016 and many external devices are not working or not even recognized anymore. For instance my Presonus audiobox USB audio interface is not working anymore.
I contacted Presonus and they told me it has to do with lower power to the USB ports. Supposedly Apple is trying to extend battery life this way.
Answer: No. This isn't a known issue on Sierra. Im sure you and some others are however seeing problems after the upgrade, but I would expect it to be a coupincidence and not a cause that you upgraded.

macOS Sierra USB Issues


Averaging with a tolerance

Question: I'm having some issues with trying to average some values. Lets say (for this example) that earthquakes are measured on a scale of 1-6. No earthquake can be stronger than a 6 and you want to calculate on average strength of the earthquakes in one area. For instance you have a single 6 rated earthquake and three 3 rated earthquakes. The way i'm calculating it, i'm getting values that make no sense. I'm weighing the earth quakes by the corresponding values saying that a single earthquake is like a 6 in my average and the three 3's are equivalent to 9 however when you take this average you get 7.5 which obviously makes no sense since no earthquake can be weighted more then a 6??? I know this is vague and i'm probably making no sense but if you do understand the jargon i'm trying to ask, could you please answer. Thank you.
Answer: To calculate the mean, you add all the values and divide by the number of them.  In your example, the mean is $\frac {6+3+3+3}{4}=\frac{15}4=3.75$, which is well within range.  When you count the number, repeated values must be counted over again.
Comment: Thank you so much. This really helps.

Averaging with a tolerance


How to hide columns in task list?

Question: I created a task list but I want to hide the columns 'Related Content' and 'Outcome' - how do I do this? I am using Sharepoint 2010 and I am a site owner. Also, what are these columns for?
Answer: go to list settings, press on Tasks content type, and from what content type setting you are able to change the visibility of the columns, just press on column you need to hide and select that option and save.
Creating task list using tasks list template creates all related columns for general usage, so if you don't need some columns, you could just remove them of hide. Or you could create custom content type with columns you want to have, and add it to the list (and remove default content types from it).
Answer: Also a good solution can be creating a new view for this task list and making it default.
With a view you can filter wich fields you want to show and wich not. Also can use the hidden column to filter the results of this view.
Answer:
Select the content type where these columns exists.
Select the metadata (column) you want to hide.
In "Column Settings" Category, there will be three options i.e.
Required, Optional and Hidden. Select "Hidden" and press "OK" to
hide the field.
Now when we go back to the new item form, the field does not show
up.
With this, we could use this solution to decide what information we
need users to input and what information we need to display in the
default list forms provided in SharePoint.

How to hide columns in task list?


Application loader stuck at the stage of "Verifying assets with the iTunes Store"

Question: I was about to upload an app to iTunes connect, but the application loader has been stuck at the stage of "Verifying assets with the iTunes Store" and pending for almost an hour. Network is fine and I have never seen this before.Has anybody encountered this kind of issue? what is the solution?thanks in advance.
Answer: This issue is predominantly on enterprise networks. There are a number of solutions please note that some of these are mere repetition of the above.
1. Make sure no pending contracts are waiting to be signed/accepted
Go to member center and make sure all contracts are signed, pending contracts will be highlighted in a big yellow/red banner at the top of the page
2.Change networks
Get off your enterprise network and tether to your cell phone (slower but works). Your home network should also work if you've not fiddled with your router
3. Get off your proxy
Change or preferably switch off your proxy. If Charles or similar apps are running, switch them off as well.
4. Use the standalone Application Loader app
This is only a walk around as it allows you to toggle the protocols. Removing Signiant & Aspera protocols works for me even in office network.

Application loader can be found under Xcode -> Open Deleveloper Tool -> Application Loader

5. Automate it!
Use FastLane tools, but remember to set     ENV["DELIVER_ITMSTRANSPORTER_ADDITIONAL_UPLOAD_PARAMETERS"] = "-t DAV" within your configuration file.
This is a lot more work than the other steps above, but provides a lasting solution. Fastlane is also really cool if you configure it correctly.
6. Cry
Because developers have bad days too.
Comment: #4 is pure gold
Comment: Thanks a lot #4 did it for me. I was at the library and I guess they have retricted internet. jsut had to untick signiant and aspera
Comment: This answer is also valid for 'Transporter' (new version of Application Loader)
Comment: Just this solution (Signiant, Aspera) worked for me. Thanks a lot.
Comment: 4 was my solution but removed in XCode 11. :/
Answer: Cancel the process and retry. If the problem persists you might want to do it via Xcode instead of ApplicationLoader. Don't forget to open an issue with Apple to let them know, after restarting AL, your Mac and reinstalling AL to make sure it can't be fixed.
Hope that helps :)
Comment: Thanks:) That strategy worked. I restarted my computer and started the uploading process again and it worked.
Answer: I recommend not to cancel.
The process seems to be stuck, but for my part waiting for 10-15 minutes finished with upload success.
Cancelling will most likely result in builds on iTunes Connect that will never finish processing. They will only be removed by iTunes Connect internal auto-cleanup after approx. 15-30 days. The downside is that it is not possible to use any build for that version number for internal testing in iTunes Connect as the indefinitely processing build version is the only one listed to choose from. The only way around is increasing the build number and you can choose it for external testing.
Comment: agree with this, i had the same thing
Comment: i don't know; i must have cancelled a 100 times, never resulted in a processing build.
Comment: Mine took 10 minutes on my corporate network. Takes about 45 seconds tethered to an LTE device off network.
Answer: I develop apps for a company that has rather tight security constraints.  I had this same issue trying to publish from behind the firewall so I got on the phone with our networking guy and sure enough there is an SSH connection to Apple that opens up to upload the app. While it makes perfect sense to secure your livelihood in transit using a SSH tunnel, to a set of security rules on a firewall it can raise flags.
If you try everything and you are publishing from within a business, consider checking the security constraints to see if you your access to Apple for that final upload isn't being blocked by default.
Answer: I was running into this, and tried all the above suggestions with no success. I then realized my app's state in iTunes Connect was in "Developer Rejected".
I removed the build I had submitted / rejected, which put the app back into the "Ready for Upload" state.
I was then able to get passed the "Verifying Assets" step.
Hope this helps!
Comment: Wau wtf how we are supposed to get this , on SO ? Thanks !
Comment: This is another bug of apple that is being ignored as they just don't care about developers...
Answer: I found this to be an issue when using free Wi-Fi from a retailer. i.e Starbucks. I was in an area where I could 6 different networks from local stores and the all hung at this stage from both Application Loader and xCode.
Don't waste your time! Join either your own network or one where you can speak with the admin. Retail Wi-Fi's lead to the dark side.
Answer: Every single time this "freeze" happens, I can fix it by going to developer.apple.com in Safari and logging in.
Magically the upload resumes after doing that. Not a co-incidence. I think it's a long standing bug where Xcode somehow loses authorization.
Comment: yeah, that magic just happened with me as well! kudos @martinjbaker
Answer: I have the same problem when I trying upload from my corporate network, but I just share mobile internet and use it, everything loading fast and without problem.
Comment: This is precisely the solution that I use every time! Tethering has been a solution to more than just one issue for me...
Comment: Tethering all the way!
Answer: The main cause for me was Review and accept new terms in the member center! Sometimes too tis a matter of unblocking https ports and removing any https proxies.
Answer: Change the wifi solved it for me
Answer: In my case, I revoked the "IOS development" and "IOS distribution" profiles, and re-create them inside Xcode -> Preferences -> Accounts -> View Details
Answer: This is a permanent issue at one of the places where I work from. And the issue is not in Provisioning at all in my case.
So, I tried to check what happens using Wireshark: I see correctly initiated SSL connection, data starts to be uploaded via UDP, but then "Retransmission" or "Spurious Retransmission" messages start happening and it all ends up either in "Destination unreachable (Port unreachable)" or connection gets reset by either side. Sometimes it happens after 2-3 seconds and sometimes in less than 1 second. Organizer tries again, but not always. Sometimes it just stops and waits for an unknown amount of time.
What I have tried:

[fail] Restarting computer or WiFi
[fail] waiting for several hours hoping the process will finish
[fail] fixing clock on WiFi router (automatic clock was turned off)
[sometimes helps] making several attempts in a row - this requires
changing build number and re-archiving. Somewhat time-consuming.
[often helps] finding another WiFi or using mobile network

I will continue playing with those router's settings and will update my answer if I find something.
Comment: Using another network really helps. My upload time is down to 2 minutes from an hour.
Answer: for me, just switch internet connection from wifi to mobile data and its working fine
Answer: I just needed a valid iOS Distribution provisioning profile. As soon as I created one it began the upload immediately.
Answer: On Xcode 8.0 (8A218a), I was having this issue.
I had added the Associated Domains capability to handle Applinks. I had accidentally left a trailing '/' on my url. Removing this trailing slash fixed the issue.
Answer: Few things to check
1. make sure you have a valid distribution provisioning profile
2. your network blocking some request during the upload.
For me I had both the issues,
after creating a valid profile, tried using my mobile hotspot and upload completed in 3 minutes.
Answer: This may well be a coincidence, but I've found that I have to unplug all my devices for the upload to finish. I'm running Sierra in VMWare, which may or may not be related ... in any case, something easy to try if you're stuck!
Answer: Had the fabric desktop app open. Closing that caused it to work right away.
Answer: Make sure your project is in "Prepare for Submission" on App Store Connect.
This happened to me as I already loaded a previous version of my app and found some new changes and was attempting to upload the new build. But the status on App Store Connect still said, "Waiting for Review". Rejecting the current build and changing the status to "Prepare for Submission" fixed the problem.
Answer: I got this error, but surprisingly I got an email later that said processing was finished for the version I was attempting to upload so apparently it was a false alarm.

Application loader stuck at the stage of “Verifying assets with the iTunes Store”


What is the easiest way to get Antlion Mandibles in Terraria?

Question: I have done everything I can in pre-hardmode, except for making a sandgun. So what's a good way to farm them? Resources aren't an issue, cause I have a lot of metal bars and whatnot.
Answer: Update: Terraria 1.3 brings with it seriously buffed antlion mandible drops, as well as a whole host of new kinds of antlions to drop them.
Getting enough for whatever you need should now be a lot easier, after running through the Underground Desert a bit.

Kill antlions.
While that answer seems facile, I'm afraid it's not just the easiest way, it's the only way*. And it takes approximately forever.
To speed up the process, you can engage in the construction of a mega project: Start a new world and convert it's entire surface to a desert, seriously increasing antlion spawning. The sand you need can be gathered from the antlions themselves as they start to spawn, as they are capable of producing an unlimited amount of sand. (Although getting any reasonable quantities of sand that way also takes, you guessed it, forever.
*: I say it's the only way, but in truth there is another: Find a server and trade for the mandibles with someone that has already done all of this.
Comment: @Jonco98 one way to improve spawning is by making floating layers above the ground level. The more layers you have on screen, the higher chance of a spawn, I believe.
Comment: Take note that the question is in reference to the mobile version of the game, which as of this date does not yet have the 1.3 update. The updated information in the answer may not be applicable.
Comment: @UnknownZombie True. Still, the question applies equally well to the mainline version, and 1.3 will make its way to mobile and console eventually, no harm in being prepared. :)


How can the date of lunar eclipses be calculated by hand?

Question: How can the date of lunar eclipses be calculated? Especially without the aid of a computer.
Comment: What sorts of eclipses are you interested in?  Solar?  Lunar?  Eclipses of the moons of Jupiter?  Etc.  Each has its own opportunities for simplifications.  (Ahh - I see the tag "moon".  I'll add that to the text for clarity....)  Next, do you want just the date, or the time also, or more information than that?
Answer: Perhaps this pdf will help. Which starts:

The calculation of eclipses is chiefly a combination of geometry and orbital mechanics. Hence, it is necessary to understand the orbital mechanics involved and also the underlying geometry.

The end of the pdf warns:

I assume that you are not trying to do an eclipse calculation exactly. If so, the problem becomes much more complicated, as you have to take into account the perturbations of all planets, the exact relation between θp, θu and the radii R1, R2, etc. In addition, you will need the initial condition of the Earth-Moon-Sun system, which you can obtain over the internet.
Comment: The ancient Greeks were able to predict eclipses long before Kepler formulated his descriptions of planetary motion, i.e., orbital mechanics for the purpose of discussion. Nor did they have the data that the PDF mentions is necessary.
Comment: @dotancohen exactly. The time span between lunar and solar eclipses seem to be so long that it is amazing that the ancients ever remembered the exact date of three of them to realise that there was a pattern.
Comment: @Stuart: Additionally, the eclipses happen at 120 degree differences over the face of the Earth, not in the same place. I have a hard time believing that that information could be used to construe any correlations.
Answer: Lunar eclipses are much easier to calculate than solar ones, and it has been done over the ages via a variety of methods.  E.g. there is evidence that the design of Stonehenge embodied some aspects of calculating eclipses.
If we can assume that you have information on previous lunar eclipses at hand, you'll observe patterns.  One of the most useful for this purpose is the pattern of near-repetition of eclipses after a Saros (Wikipedia), which is a period of approximately 6585.3213 days, or nearly 18 years 11 days.  One saros after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle.  That is because a saros is a nearly whole number of repeats of each of three cycles  of the lunar orbit: the synodic month, the draconic month, and the anomalistic month.  See the article for details.
After decades of observation (or via access to tables like the List of Saros series for lunar eclipses or the  Five Millennium Canon of Lunar Eclipses: -1999 to +3000), you'll have a list of the currently active saros series.  It is then easy to extend any particular saros series by hand, using the information in the saros article.  If there is a particular date you're interested in, we could work through an example here.


Is there software that allows employees to make their own site (on the company domain) without the ability to mess up the rest of the site?

Question: I manage a site for a school and the staff (teachers specifically) use the site Weebly to create a personal site to inform students of new assignments, or embed content like lesson plans for students who may have missed class, etc. I looked at CMS like Bolt but I don't know if that is what I really need. What I want is to give them sub domains of the main site, like teacher.example.com or example.com\teacher where they can edit their own small portion of the site and update it to meet their needs. They only need the ability to edit text and maybe upload a picture or two, the sites will follow the general formatting of the framework being used currently. Preferably the second option example.com\teacher is much easier to manage because getting sub domain access (from the county) is a hassle. Please also note that these are teachers who are not fluent in any coding so a WYSIWYG editor is a must.
Comment: schoolmessenger.com/cms-for-schools looks slick and professional - and probably not free, although I can't see any indication of pricing
Comment: Education focused CMSs http://www.cmswire.com/cms/web-experience/5-educationfocused-web-content-management-platforms-021526.php
Answer: Have a look at Drupal, and its feature called "Multi-Site" to share the same code base with as many sites as you'd want. In your case you could have 1 such site for each teacher (and the WYSIWYG editor you're looking for is typically implemented using the CK Editor module).
Maybe you also want to investigate the available Drupal "Distributions", which provide site features and functions for a specific type of site as a single download containing Drupal core, contributed modules, themes, and pre-defined configuration. They make it possible to quickly set up a complex, use-specific site in fewer steps than if installing and configuring elements individually.
For (a lot of) suggestions about using "Drupal as a LMS", refer to my answer to the question "Drupal as a LMS. Learning platforms based on Drupal, or integrated with it"
Comment: Yup, I love Drupal. But I also appreciate the CMS selection wizard and CMS comparision features at http://cmsmatrix.org/ which surprisingly few people seem to know about
Comment: Thank you so much! I just took a look at Drupal, and I must say that it looks quite good. I've already started trying I get it integrated into the website and it looks as though it will perform nicely for this! Also, thank you to all the other responses to my problem!
Comment: Thank you for your accept ... I just realized I forgot to +1 your interesting question also, which is what I just did ... If you have more (drupal) related questions when moving forward on this, leave a comment around here if you want to bring that to my attention also!
Answer: Is there a major difference between primary and secondary schools?
Disclaimer: I am not a teacher (although I did go to school with children), so I have not personally tried this product. Btw, it was surprisingly easy to find (GIYF). Try the demo and see if it is for you. It certainly seems to meet your needs.

What is SyndeoCMS?
A Content Management System (CMS) for primary
  schools, which helps you manage and maintain your website. It can also
  be a very usefull CMS for small companies or non profit organizations.
It is Open Source Software (that means free to use), licensed under
  the General Public license. Syndeocms is my continuation of
  Site@School 2.4.10. see History for more details.
Main features are:
  - You can manage a website without technical knowledge.
  - It has an editor with a high "Word look and feel" rate (FCKeditor).
  - Pupils and teachers can have personal pages on the website.
  - Teachers can check pupil pages before publication.
  - Project   pages for pupils and teachers.
  -  An intranet for teachers which is not  accessible by the public.
  - A lot of modules (like a guestbook and newsletter) for your website, see available Modules Template editor or
  you can create your own template, see creating templates
  - is LAMP or  WAMP compatible (i.e., Linux or Windows server)
  - Backup feature to make  a local backup of the mysql database.
  -  Translation tool to change the language files to your needs or create a new translation.
  - And much  more.
How do I get started You could try our demo site and look for yourself if the system suites you.
Answer: If I may recommend WordPress, it too has a feature called multi-site which always to create subdomains off an existing domain where you can give access to specific sites for specific employees. It's open source and very easy to use and setup. It also includes a very easy to use page/post editor and you can also add plugins that add functionality to this editor as well.


How do I define "by" versus "through" to my students?

Question: Over the past five years, my high school students have stopped using "through" as a preposition and use "by" almost exclusively.  For example, they might write, "they will do this by a detailed research project".  I have looked up the answer and I can't figure out a way to explain the difference to them, and I almost think that I just need to let it go.  Does anyone know why these two words have become virtually interchangeable?
Comment: You mean they don't say "They walked through the forest", they say "They walked by the forest" instead? That's serious. If you **don't** mean that, you might try thinking about the contexts the prepositions are being used in. Hint: metaphor.
Comment: @Alice, Japanese students?
Answer: Prepositions are perhaps the most polysemous of words. And all words are polysemous.
It's tempting to say 'You just have to learn every individual collocation'. So don't start teaching until you're past retirement age (by which time usages will have changed anyway, so you'll have to go on a refresher course ...).
As jimsug says, there are instances where the two prepositions are definitely not interchangeable; often, they are highly idiomatic:

I learnt it by heart/rote.
*I learnt it through heart/rote.

.............

*She stuck with him by thick and thin.
She stuck with him through thick and thin.

Though they may be central senses (directional / locative):

I drove by the site of the old Chicago Motor Speedway. =/=
I drove through the site of the old Chicago Motor Speedway.

In  'they will do this by / through a detailed research project', the more peripheral sense/s of agency/means are in play:

I could tell it was you by what you were wearing.
He made it by hand.
We went by car.
He only discovered this by chance / through good fortune [far more common than the
  next alternative ?!] / by good  fortune.
You will only succeed through hard work / by working hard.

'They will do this by a detailed research project' is possibly best considered as an ellipted form of

'They will do this by carrying out a detailed research project' or
'They will do this by means of a detailed research project' or
'They will do this through the expediency of carrying out a detailed
  research project' or
'They will do this through the expediency of a detailed research
  project'.

This is perhaps an illustration of part of the evolutionary processes that can be involved.
Answer: In this case, looking to the etymology of the words helps. According to the OED, both by and through can be traced back to Old English (though, through does go back beyond that). The key difference here is that through is actually derived from thorough, and as such refers to the sole means through which something is accomplished, from start to finish. By was initially in contrast to byway, where a byway was the primary path of travel and a by was the secondary.
Essentially, through trumps by in terms of importance of the object of the preposition, and in prescriptive rules they cannot actually be used interchangeably. Descriptive English, however, allows them to be used interchangeably, because people already do.
Answer: Looking at some definitions from Collins:

by
through

I'd say because of the overlap in meaning and usage (through is even used as a definition for "by"), people (and not just kids, although they seem to have quite the role in language change) use them interchangeably.
You should be able to demonstrate the differences by providing examples where they're not interchangeable, eg:

He was accepted as a member of the bandicoot totem by his own male relatives
*He was accepted as a member of the bandicoot totem through his own male relatives

or

It's possible to improve your fitness through exercises.
*It's possible to improve your fitness by exercises.

I would probably let your example slide, as it communicates a similar process/event, and is grammatical with either by or through.
Comment: The method you propose is sound. However, the Mubarak text could have been better selected; even the *by* sentence is sloppily constructed and doesn't clearly demonstrate the point you are trying to make. I suggest you substitute a better example.
Comment: @ErikKowal yeah, I was thinking that as I re-read it. This one works better.
Comment: The new sentence is better constructed, but there are two problems: 1) 'Readings' does not work with either of the versions -- it should be 'reading'. 2) Unfortunately, if it's changed to 'reading', then the sentence works equally well with both 'through' and 'by'. I'm afraid you'll have to find yet another pair of sentences to illustrate the difference in usage.
Comment: @ErikKowal perhaps this example is too localised? I mean readings as in "readings set for students", for instance. Maybe adding that to the answer would help...
Comment: @ErikKowal "exercises", that works, right? Finally got there ;)
Answer: A --> B --> C
From a through (tunnel b) to c.
From a via (road b) to c. (via is way or road in latin)
From a by car via b to c.
From a with car through b to c.
From a by car by b to c. Nope. Passing by maybe.
By --> by way of (over, passing by, but not passing through)
through --> you need to you through the wood in order to come out on the other and there is no way to pass it by.
So through is like a roadblock that you need to take in order to arrive on the other end of the road.  Aka. a mountain with a tunnel.
Answer: If one learns something "by means of" X, it is neither "through" nor "by," and indicates that a thing was learned by means of a certain process, whether that be education, experience, scientific inquiry, etc.
Question.  Examples given: He was accepted as a member of the bandicoot totem by his own male relatives, and, *He was accepted as a member of the bandicoot totem through his own male relatives.  If the asterisk is used to indicate correct usage, that is wrong.  "By" is correct.  He did not travel "through" his relatives.


No radiator fluid in resevoir

Question: Obviously you shouldn't drive with no coolant, because in most cases obviously your car will overheat, blow a head gasket and all that fun stuff. I drive a 4cyl 2.5L Ford Ranger. One time I realized it had none in it, I planned on getting some but I forgot the next day. I drove it for about a week before remembering. My truck never even came close to over heating ... can anyone explain?
Comment: How much water is left in the radiator? Even if there's some air inside, the engine gets its water from the bottom and so may not suck in air. Cooling may be less effective, but _yet_ without adverse effects.
Answer: If you didn't have any coolant in the cooling system at all, your engine probably wouldn't last more than 15 minutes driving in a moderate climate before it seized.  Just because you can't see any in the reservoir which only holds a small amount, it doesn't mean there isn't any in the engine, radiator, pipes etc.  Obviously if you can't see any in the reservoir, you don't have a clue how much is really in there, so it is not a good idea to drive like that.  Presumably you only had to add a small amount (a couple of pints maybe) to bring it back to normal.  If this happens again, don't presume you can get away with it.
Answer: Just because you don't see any coolant in your overflow/reservoir, doesn't mean the system doesn't have enough fluid in it to keep your engine from over heating. There are other factors involved as well:

Engineering of your particular vehicle may not require as much coolant as it normally would have ... ie: the vehicle engineers over engineered this one part of your vehicle. Feel lucky if this is the case.
You may not have put much stress on the vehicle to cause it to overheat.
Your climate may not be overly hot, which may not need as much coolant or coolant capacity.

I think the bigger thing to be thinking about here is why was your reservoir tank low in the first place? For the most part, the cooling system is a closed system, meaning it shouldn't be loosing/gaining coolant. If everything is as it should be, it should stay relatively the same (might be small fluctuations). If your reservoir has become empty, you need to figure out why it became empty so it doesn't happen again. Is the engine sucking in the coolant and burning it? Is it draining out on the ground? Did it overheat a little and come gushing out the overflow? Whatever the reason, I'd be on the lookout for it and get it fixed.
Comment: If the coolant level is low, you could end up with a cool block and a hot head :)

No radiator fluid in resevoir


Why did they break their cups after a toast?

Question: In episode 17 when they're about to welcome Satsuki's mother, they're having a toast and slam their cups to the ground. Why did they do it? Does this have anything to do with Japanese culture?
Comment: Related information: [What did they use for their toast](http://anime.stackexchange.com/q/7424/1458)
Answer: It's from a Russian tradition that went back to Peter the Great and now it's done after important toasts.
From the Table-glass Wikipedia page (bold emphasis added):

A legend says that the first known faceted glass was given as a present to Tsar Peter the Great from a glass-maker called Yefim Smolin, living in Vladimir Oblast. He boasted to Tsar that his glass couldn't be broken. Tsar Peter liked the present, however, after drinking some alcoholic beverage from it, he said loudly Let the glass be! (Russian: Стакану быть! - literally the glass be), threw the glass on the ground and managed to break it. But Peter didn't punish the glass-maker, and the production of such glasses continued. According to the legend, people present during this episode misinterpreted the Tsar's words and thought that Peter called to break the glasses (Russian: Стаканы бить! - literally beat glasses or break glasses), that's how a tradition of breaking drinkware on certain occasions appeared in Russia. Glasses were broken after especially important toasts or just during the especially cheerful parties. Russian restaurants even held a special prices for breaking the glasses. Breaking of drinkware, or, in wider context, any tableware, is believed in Russia to bring luck and happiness.
Answer: I'm sure Jon Lin is correct about the background, but here is a more in-universe answer:
As user1306322 stated in a comment, it's likely based on a ritual done before going into a battle you don't expect to return from. In episode 23,

they toast again, but this time Satsuki says not to break the cups as that time they're not going to their deaths (in her words, approximately).

This leads to the assumption that when they toasted in this episode, they did not expect to return.
Answer: Another potential source, in addition to the already-mentioned sources and possibly influences by them, is earlier anime. Kill la Kill makes frequent direct and indirect references to earlier works, and this scene from a prominent 80's sci-fi anime Legend of Galactic Heroes could have been what they are referring to by breaking glasses.
Admittedly, this is hardly the first instance of Germanophilia or Semitophilia in anime or Japanese culture in general and its sources could be earlier.
Answer: This is based upon many light novels that I have read. Typically the breaking of the glass after a toast denotes a finality to whatever you are toasting. If you toast before parting you don't expect to see each other again, if you post welcoming someone into your family it implies a permanence to that acceptance.
I have also read in some that it is implied that "until this toast is undone (repair of the cups) this is permanent." So in this one story they break the cups at the beginning of a journey and repair them when them come home to toast again.
Comment: Hi, could you add references to some of the light novels and their specific scenes (e.g. chapter no./page no.)?
Answer: Breaking of glasses occurs twice in the yakuza film Tokyo Drifter (Suzuki, 1966), once in the formal introductory ritual between Tetsu's and the northern boss (actually a dish of sake); and in the final scene where

 Tetsuo breaks his oath of loyalty to his boss, symbolically crushing a wine glass in his hand.

Neither is a formal toast, and each involves only one party. However this (particularly the first ritual) is an example of breaking a drinking vessel in ritual fashion.
Comment: Please include relevant sources/references to support your answer.


Special Relativity- Lorentz transformation

Question: We know that in lorentz transformation , x'= lorentz factor*(x-vt)
Suppose, that in unprimed frame , x=0 ; and the primed frame moves with velocity c wrt unprimed one. Then accor to the transformation, x'=-(infinite), as lorentz factor is infinite. But how can infinite distance be traversed by the primed frame with respect to the unprimed frame at a finite time?
Answer: First of all, the Lorentz transformation $x'=\gamma (x-vt)$ is not for distances, but for single events. Here $x'$ represents the position where some event occurs in the moving frame and approaches $\infty$. This isn't really possible because it would take an infinite amount of energy to accelerate an object with mass to $c$ which is why the $v=c$ frame does not exist.
Comment: @Syed, according to SR, there is no inertial reference frame for light, light has speed *c* in *all* inertial reference frames, there is no rest frame for light, there is no inertial reference frame with relative speed *c*.
Comment: But what if we take the primed frame as light itself?


Getting to know my way around a database with hundreds of tables

Question: I'm new to a small company that's pretty much run by one guy. He knows all the ins and outs of the system which is quite large. We have a database with about 300 different tables. I'm struggling to keep track of where everything in the database is and what relates to what. What methods can be used to manage large databases, or does it mostly come down to going through other examples in the code base to find what you need?
Comment: Documentation? Its no different to any other large system. You just have to get in there and understand it, bit by bit, until you're an expert too.
Comment: I misunderstood the question; for me a large database is a multi-terabyte or a petabyte one (it could have few tables with few columns, but it should have many rows)
Comment: @Peck3277: How to eat an elephant? One bite at a time. Your question is very similar to this one (http://programmers.stackexchange.com/questions/155488/ive-inherited-200k-lines-of-spaghetti-code-what-now) or this one (http://programmers.stackexchange.com/questions/6395/how-do-you-dive-into-large-code-bases), and I guess you can get the answers you are looking for from those question & answers.
Comment: Just repeatedly ask the other guy who didn't bother to document anything. Maybe he'll get the hint.
Comment: Are you dealing with an ORM?
Comment: By large I mean lots of tables, not necessarily a lot of rows. It's more the relationship between the tables. I think gbjbaanb is right about the documentation, I just have no idea how I'd go about documenting this as none was ever kept :/
Answer: For the database that I am responsible for I do the following:

expose all metadata in views so you can see groups of related tables in a more human readable fashion
every view/table has a comment, every column has a comment. Yes, it's a pain but it helps new people
every function/procedure/trigger has a one line comment that starts with Summary.  I extract the procedure/function name and comment into a table.
Toad has an option to document your database as an html file. It makes for dry reading but it is another means to access the structure
have a library of standard queries used to access commonly requested information
have packages that will implement commonly requested items like access, new metadata, disabling metadata
don't be too clever. That brilliant code you wrote in a flash of insight is not likely to be understood by you six months later or a new team member.  If you must, document and comment the code.
Answer: What have worked for me is:

Plot a giant physical model of the database.

You must use a tool like Sybase Power Designer and reverse-engineer the model. There are also free tools that could be used. Once there you must find a plot service and have it plotted in big format. Then put it on the wall.
It helps if you first re-format the model for better readability of relatioships. What I do is:

Use non-diagonal lines
Have the join printed with every relationship
Prevent overlapping lines.
Minimize crossing lines
Group tables in clusters