Is there some difference between blue light and light covered by blue paper?

Question:
Let´s talk only about photons absorbed by detector. Would it detect something else if the photons came from blue star than if the photons were filtered by blue paper?
And what about ultraviolet paper?
Comment: The term you're looking to study is ["matamerism"](http://en.wikipedia.org/wiki/Metamerism_(color))
Answer: No star emits a single frequency of radiation - they all emit a spectrum, and the wavelength of the light that's most intense in the spectrum depends on the temperature of the star.

The spectrum of the light transmitted through a blue paper depends on the transmittance of the paper for the different frequencies that make up white light.
In the off-chance that both spectra are identical, you could say both blues are identical.
Answer: This question is partly a biology question, because color, blue in this case, is labeled by human perception of what blue is.
As far as physics is concerned, photons make up light and photons come in all frequencies of the electromagnetic spectrum. That spectrum, the optical part known as rainbow.

Pure spectral colors .

The biological perception by the receptors in our eyes retina sees and registers the blue of the spectrum as blue, i.e. the photons/light of wavelength 450-495 nanometers.
But our perception is very much more inclusive, and can have combinations of other frequencies raising the perception "blue" without the frequency blues being there.
Edwin H.Land  , the inventor of Polaroid cameras, showed that one could get a perceived full color picture by just using two frequencies for illumination.
The blue light coming from the stars through the mostly void  has the frequency of blue. The blue of a blue paper might have it or might not , or the photons coming through might have a mixture of frequencies that raise the perception "blue" in the brain.
Just two frequencies could do it, as was  shown in the demonstration. There is blue where there is no frequency blue .
Answer: The only properties a single photon has are its direction of propagation and its energy/frequency/wavelength. So a photon of a given wavelength coming from some direction is just that -- it doesn't carry extra information about what caused it to be coming from that direction with that particular wavelength.
Now there is a caveat that has to do with interpreting the wording of your question. If by "blue" you mean "wavelength of 450 nanometers," then the above is all there is to say on the issue. Often in science we use "color" interchangeably with "wavelength."
However, if by "color" you mean "as seen by the human eye," then there is likely some difference. In practice, any source of light, whether it be a star or an illuminated piece of paper, has a detailed spectrum -- a distribution of how much light is at each wavelength. This is what you see when you break up light with a prism or a diffraction grating.
These spectra will in general be different for different sources, since all sorts of things can affect them. For example, gasses in a star's atmosphere absorb very specific wavelengths, preventing these from reaching you. The molecular bonds in the paper will absorb different wavelengths.
Now because the eye only has three color receptors, and all of these sensitive to a broad range of wavelengths, fine details in spectra are lost to us. There are many different spectra that will produce the same levels of stimulation in these receptors and thus be seen as identical colors. In this sense there are different "blues" and we would need a spectrograph rather than our eyes (or even regular cameras, which are similar to our eyes in this regard) to detect the difference.
Since UV is just slightly shorter wavelengths than visible light, all of the same discussion holds there.
Answer:
Yes, probably. There are a lot of ways that your eyes/brain can see "blue" with different mixtures of light. A star, paper, and an LED will all have different combinations based on the way they make that color, but it can still look the same to you. A spectrometer, which can analyze the actual mixture of frequencies entering it, will be able to distinguish from these. A camera may or may not see them differently, since a camera works more like your eye, but with different ways of measuring the mixture of light.
Yes, for the same reasons, except that your eye wouldn't really know what to make of ultraviolet paper. I suppose it would just be black.


Do modern fiction writers adapt their style to the 21st century reader?

Question: With shortening attention spans and the way we consume content nowadays, is there any shift in the way modern fiction books are written? Do contemporary writers write differently than those living in the non-digital era?
Comment: Hi daskas! Welcome to Writing.SE! Take a look at our [tour] and [help] pages, they're great for figuring out how our site works. The answer to "do writers now write differently than before" is yes, always: like every art, writing keeps changing and evolving. Enumerating all the differences is too broad a question. But if your question is whether your writing should differ from examples of 50, 100, or 200 years ago in terms of pacing, that is quite answerable. You might want to [edit] your question to make it more focused on that one aspect, though.
Comment: You can indeed ask "how". The problem (and probably why you're getting downvotes) is that this SE is for writers trying to help other writers: we are rather focused on "how to write" questions. If you seek only to understand existing literary works, but not to write your own, your question is a better fit for [literature.se].
Comment: Thank you for your comment and suggestion, Galastel! I was asking mostly as a reader, not a writer. Perhaps this site isn't best suited for these kind of questions, but wanted to try my luck. Would it help if the question was phrased as "How" instead of a closed variant Do/Should or if I were asking for examples?
Answer: Are writers changing to accommodate short attention spans?
Yes, in some ways.  The flash and micro flash formats seem a product of the digital age and are written to convey a complete story in 100-1000 words.
But, General Audience novels and short stories aren't shorter. The reading level of the language might be a little lower, but that is because of an attempt to reach a broader audience. And style has certainly continued to evolve and change as what is considered more interesting has changed.
For instance, Sci-fi from the 1930-1950s was much lighter on characterization.  Today, character-driven stories are the fashion for most pro-rate publications. And it will change in the future to something else.
I think that there exists this impression because of the writing they see on most advertising-supported web pages.  These are intended to be read quickly and are reaching a broad segment of the population -- like tweens and teenagers to retirees.  Since the goal of the publishers -- or web site -- is to push as many advertisements in front of as many eyes as possible, they don't want people to linger over a story.  They want people to read, share and repeat.


FQL query to stream still returning unreliable results?

Question: I am trying to use FQL to query the stream table and retrieve news feed items. Like this:
<code>SELECT post_id, actor_id, target_id, message, created_time
FROM stream
WHERE filter_key in
    (SELECT filter_key
     FROM stream_filter
     WHERE uid=me()
     AND type='newsfeed'
     )
AND is_hidden = 0
</code>
Following the suggestion here, I've been trying to use epoch timestamps (created_time) to limit the number of items returned and paginate everything (seems like a kludge, but OK, if that's the best we can do). However, any time I specify the cutoff as earlier than a day or so (haven't nailed down the exact pattern yet), it returns null. No error message... just "data": [].
I know there have been a lot of issues with paginating the stream table in the past, but this seems like an old bug (if it's still a bug and not my oversight). Has anyone figured out how to deal with this? I can get better results if I leave any reference to filter_key out of the query, but I need to use it, so that's not really a solution.
Answer: I had a very similar issue and I fixed it by removing the
filter_key in
    (SELECT filter_key
     FROM stream_filter
     WHERE uid=me()
     AND type='newsfeed'
     )
from my query. What I did was initially did a query to get the filter key, and saved the filter_key string to then use in all my subsequent queries. This worked for me


How does SNMP manager gets MIB from devices

Question: I have been studying SNMP for a while. I understood SNMP manager can query a particular OID within the managed device's MIB. In order to do that the SNMP manager must know the MIB of the managed device first. I read MIBs are stored in files. Now how does Manager know about the MIB of each devices of the network. Does the manager send a request to the snmp agent for sharing the MIB or it has to be loaded manually?
Answer: You have to install and load relevant MIBs to the manager manually. A number of MIBs are standard and come preinstalled with many SNMP solutions, but vendor MIBs for specific devices are often hard  or impossible to get, outdated, difficult to find, with the requirements to sign NDAs and whatnot else.
Just downloading the MIB from the device would be a dream that would make working with SNMP actually sufferable...
But: Strictly speaking, you don't need MIBs at all, you can just walk the OID tree and download everything or a specific OID, but of course then you have to play the guessing game what the data actually means.
Comment: Hope you can weaken the part of "you don't need MIBs at all". As you described later, such documents are still keys to understand the meaning of the objects.
Comment: @LexLi: I don't recommend working without a MIB, not at all.  However, you *can* work without it if you just can't get an MIB for the device for whatever reason and you can figure out somehow what OIDs contain the data that interests you. It's not fun, it costs time but with the state of support you get for SNMP from vendors, it's sometimes the only option.


Wiring for island D/W and GFI and Garbage Disposer

Question: Currently under sink I have a 12/3 and a 12/2 wire that come into a junction box. The 12/2 comes from another wall GFI and the 12/3 comes from the breaker panel. How can I connect wires in box to add the necessary GFI outlet on the island along with an undersink outlet and switch for the plug in disposer and run the direct wire to the hard wire D/W.
Answer: The wiring should look something like this...

Grounding conductors not shown
Depending on where you live, the disposer receptacle may or may not have to be GFCI protected. The drawing shows GFCI protection, but it may not be required.
Also, if the line coming to the other receptacle is already GFCI protected, you don't need a GFCI receptacle there either.
Comment: Except he said the 12/2 comes from another wall GFI (outlet presumably) so the receptacle on your left doesn't need to be GFCI (as long as it's fed from the `LOAD` side).  Your handling of the complex MWBC+GFCI situation is right on the money.
Comment: Thanks, @Harper. I mentioned in the post that the GFCI receptacles may not be required.  Just keep in mind, simply because a line comes from where a GFCI is installed, does not mean the line is GFCI protected.


How to know whether cancel button is clicked in Save Prompt dialog box , when we try to close Unsaved Word document in C#

Question: I am working on C# word application. Currently I am using DocumentBeforeClose event for cleaning activities, disposing the objects when user tries to close the particular word document (Of multiple documents). The problem I am facing is that when user makes some changes to word document and he tries to close the document without saving. Then DocumentBeforeClose event is fired and my logic is executed, but after that Dialog message box appears with "Do you want to save the document?". If the user clicks on Save or Don't Save option the word document is closed, but when user clicks on cancel button or closes the dialog box we would be still there in word document, but I would have disposed the objects related to that document as the event(DocumentBeforClose) is already fired and user can't work with document afterwards. Is there any way I could know whether the cancel button is clicked or not? I tried listening to window messages such as WM_Cancel , but they are not working for me. How can I overcome this scenario?
If I save the document in DocumentBeforeClose event it is working, but I don't want to save the document by default as user should have the control over this.
Comment: Have you tried listening for the shutdown event? https://learn.microsoft.com/en-us/visualstudio/vsto/events-in-office-projects?view=vs-2022
Answer: You can check if the if the document needs saving or not by checking the document.saved property.  Then you can control the logic and user actions from there and not rely on Word's built in 'do you want to save'.
check if document needs saving


Logistic Regression Model on Head to Head Observations

Question: I have a dataset containing the outcomes of head-to-head matches of a game.
I would like to fit a logistic regression model with target variable being the winner of the match and using var_a and var_b as two predictors. The first, var_a is a continuous variable and the second, var_b is a binary variable. For this, I am considering using the difference in var_a between the player and the other player in the match as a predictor rather than the raw values of var_a.
An example few rows might look like this:

match_id
winner
var_a
var_b

1
0
80
1

1
1
76
0

2
0
54
0

2
1
68
0

3
0
71
0

3
1
78
1

As you can see, there are two observations per match.
I feel like if I simply fit a model using all rows of my data, I will run into problems based on the fact that each match would be included twice. This feels almost like a paired samples t-test except for the fact that I have a third variable, var_b which may or may not be present in a given match. For example, in match 2, neither player had var_b.
My thought was to do a bootstrap-esque procedure where I randomly select one observation per match, fit a model, and record the coefficients and then repeat a few thousand times to generate confidence intervals for my coefficient estimates. This is not the same as the bootstrap, since I would not be sampling with replacement, but I'm not sure if any kind of standard bootstrap approach would be appropriate. Perhaps a cluster bootstrap could work?
Is the procedure that I have outlined a reasonable approach or is there some other method which could give me better estimates for the coefficients?
Answer: You could try fitting a logistic regression with 4 predictors: var_a[player_1], var_a[player_2], var_b[player_1], var_b[player_2], the target variable being 0 or 1 (0 if player_1 wins or 1 if player_2).


migrating a document library from sharepoint 2010 to sharepoint 2013 without using 3rd party tools

Question: I have to migrate a document library from sharepoint 2010 to sharepoint 2013 without using any 3rd party tool. any nice approach to achieve it?
Answer: Their are 3 ways to get this done.

Export from 2010 and import in 2013(with little tricks)
Content Database Migration
3rd party tools.

Method 1.

Export the list from SharePoint 2010 using either the Central
Administration or PowerShell (Export-SPWeb). In the Central
Administration, go to Backup and Restore > Export a site or list.
Choose your list, and click Start Export
Copy the exported list (.cmp file) to your desktop and change the extension to .cab. You can then extract it using a software like WinRar.
Open the SystemData.XML file with an editor like NotePad++ and change the version from 184.108.40.206 to 188.8.131.52 , and the build version from your 14.0.x.x to 15.0.x.x (depending on the build you have on both your farms). Here is a screenshot with before and afte
Now we have to repackage it as a .cab file. I used a software called CabPack. Select your Source and Destination. Change the CabinetNameTemplate if you want, and click on OK.
Change the extension from .cab to .cmp
Copy the .cmp file back on the network share or directly on the SharePoint 2013 Server.
Open SharePoint 2013 Management Shell as an administrator. Run this command by changing the parameters of course! Import-SPWeb -Identity http://teamsite.vlad.local/ -Path \sp2010-itest\Exports\MyCusttomList.cmp -Verbose
Open up your SharePoint Site and your list should be there

source:http://absolute-sharepoint.com/2013/08/how-to-move-a-list-from-sharepoint-2010-to-sharepoint-2013.html
Method 2)
I am sure you already have you 2013 farm up and running.

Backup the Content Database of the Site Collection in which the list
is. (SharePoint 2010)
Create a Temporary Web Application in the SharePoint 2013 Farm.
Run SharePoint 2013 Management Shell as an administrator, and run the
following command to dismount the content database:
Get-SPContentDatabase -WebApplication http://sitename.com | Dismount-SPContentDatabase
Restore the Backup you took in Step 1, on the SQL Instance hosting
your SharePoint 2013 Farm. Make sure you give the farm account
db_owner permissions on the database.
In the SharePoint 2013 Management Shell, run the following command.
Mount-SPContentDatabase MyDatabase -WebApplication http://sitename.com
Navigate to the Site Collection, and if you didn't have too many
development and custom things done, it should open no problem. Make
sure the list you want to export is ok.
Go in the Central Administration, go to Backup and Restore > Export a
site or list. Choose your list, and click Start Export
Open SharePoint 2013 Management Shell as an administrator. Run this
command by changing the parameters of course! `
Import-SPWeb -Identity http://teamsite.vlad.local/ -Path \sp2010itest\Exports\MyCusttomList.cmp -Verbose
Open up your SharePoint Site and your list should be there
Comment: Thanks Waqas,you made my day. Let me try to implement the same.
Answer: For simple migration you can use:

Open both libraries in explorer view and simply copy paste the files on both the libraries.
Using powershell script
http://gallery.technet.microsoft.com/office/Copy-all-SharePoint-Files-0999c53f
Try saving your list as template and create new document library with that template.
Free tool available at codeplex to migrate documents

http://spdocsmigrator.codeplex.com/


Exercise: 2D orbital mechanics simulation (python)

Question: Just a little disclaimer beforehand: I have never studied astronomy or any exact sciences for that matter (not even IT), so I am trying to fill this gap by self-education. Astronomy is one of the areas that has captured my attention and my idea of self-education is head on applied approach. So, straight to the point - this is orbital simulation model that I am casually working on when I have time/mood. My major goal is to create complete solar system in motion and ability to plan spacecraft launches to other planets.
You are all free to pick this project up at any point and have fun experimenting!
update!!! (Nov10)

velocity is now proper deltaV and giving additional motion now calculates
sum vector of velocity
you can place as many static objects as you
like, on every time unit object in motion checks for gravity vectors
from all sources (and checks for collision)
greatly improved the performance of calculations
a fix to account for interactive mod in matplotlib. Looks like that this is default option only for ipython. Regular python3 requires that statement explicitly.

Basically it is now possible to "launch" a spacecraft from the surface of the Earth and plot a mission to the Moon by making deltaV vector corrections via giveMotion(). Next in line is trying to implement global time variable to enable simultaneous motion e.g. Moon orbits Earth while spacecraft tries out a gravity assist maneuver.
Comments and suggestions for improvements are always welcome!
Done in Python3 with matplotlib library
import matplotlib.pyplot as plt
import math
plt.ion()

G = 6.673e-11  # gravity constant
gridArea = [0, 200, 0, 200]  # margins of the coordinate grid
gridScale = 1000000  # 1 unit of grid equals 1000000m or 1000km

plt.clf()  # clear plot area
plt.axis(gridArea)  # create new coordinate grid
plt.grid(b="on")  # place grid

class Object:
    _instances = []
    def __init__(self, name, position, radius, mass):
        self.name = name
        self.position = position
        self.radius = radius  # in grid values
        self.mass = mass
        self.placeObject()
        self.velocity = 0
        Object._instances.append(self)

    def placeObject(self):
        drawObject = plt.Circle(self.position, radius=self.radius, fill=False, color="black")
        plt.gca().add_patch(drawObject)
        plt.show()

    def giveMotion(self, deltaV, motionDirection, time):
        if self.velocity != 0:
            x_comp = math.sin(math.radians(self.motionDirection))*self.velocity
            y_comp = math.cos(math.radians(self.motionDirection))*self.velocity
            x_comp += math.sin(math.radians(motionDirection))*deltaV
            y_comp += math.cos(math.radians(motionDirection))*deltaV
            self.velocity = math.sqrt((x_comp**2)+(y_comp**2))

            if x_comp > 0 and y_comp > 0:  # calculate degrees depending on the coordinate quadrant
                self.motionDirection = math.degrees(math.asin(abs(x_comp)/self.velocity))  # update motion direction
            elif x_comp > 0 and y_comp < 0:
                self.motionDirection = math.degrees(math.asin(abs(y_comp)/self.velocity)) + 90
            elif x_comp < 0 and y_comp < 0:
                self.motionDirection = math.degrees(math.asin(abs(x_comp)/self.velocity)) + 180
            else:
                self.motionDirection = math.degrees(math.asin(abs(y_comp)/self.velocity)) + 270

        else:
            self.velocity = self.velocity + deltaV  # in m/s
            self.motionDirection = motionDirection  # degrees
        self.time = time  # in seconds
        self.vectorUpdate()

    def vectorUpdate(self):
        self.placeObject()
        data = []

        for t in range(self.time):
            motionForce = self.mass * self.velocity  # F = m * v
            x_net = 0
            y_net = 0
            for x in [y for y in Object._instances if y is not self]:
                distance = math.sqrt(((self.position[0]-x.position[0])**2) +
                             (self.position[1]-x.position[1])**2)
                gravityForce = G*(self.mass * x.mass)/((distance*gridScale)**2)

                x_pos = self.position[0] - x.position[0]
                y_pos = self.position[1] - x.position[1]

                if x_pos <= 0 and y_pos > 0:  # calculate degrees depending on the coordinate quadrant
                    gravityDirection = math.degrees(math.asin(abs(y_pos)/distance))+90

                elif x_pos > 0 and y_pos >= 0:
                    gravityDirection = math.degrees(math.asin(abs(x_pos)/distance))+180

                elif x_pos >= 0 and y_pos < 0:
                    gravityDirection = math.degrees(math.asin(abs(y_pos)/distance))+270

                else:
                    gravityDirection = math.degrees(math.asin(abs(x_pos)/distance))

                x_gF = gravityForce * math.sin(math.radians(gravityDirection))  # x component of vector
                y_gF = gravityForce * math.cos(math.radians(gravityDirection))  # y component of vector

                x_net += x_gF
                y_net += y_gF

            x_mF = motionForce * math.sin(math.radians(self.motionDirection))
            y_mF = motionForce * math.cos(math.radians(self.motionDirection))
            x_net += x_mF
            y_net += y_mF
            netForce = math.sqrt((x_net**2)+(y_net**2))

            if x_net > 0 and y_net > 0:  # calculate degrees depending on the coordinate quadrant
                self.motionDirection = math.degrees(math.asin(abs(x_net)/netForce))  # update motion direction
            elif x_net > 0 and y_net < 0:
                self.motionDirection = math.degrees(math.asin(abs(y_net)/netForce)) + 90
            elif x_net < 0 and y_net < 0:
                self.motionDirection = math.degrees(math.asin(abs(x_net)/netForce)) + 180
            else:
                self.motionDirection = math.degrees(math.asin(abs(y_net)/netForce)) + 270

            self.velocity = netForce/self.mass  # update velocity
            traveled = self.velocity/gridScale  # grid distance traveled per 1 sec
            self.position = (self.position[0] + math.sin(math.radians(self.motionDirection))*traveled,
                             self.position[1] + math.cos(math.radians(self.motionDirection))*traveled)  # update pos
            data.append([self.position[0], self.position[1]])

            collision = 0
            for x in [y for y in Object._instances if y is not self]:
                if (self.position[0] - x.position[0])**2 + (self.position[1] - x.position[1])**2 <= x.radius**2:
                    collision = 1
                    break
            if collision != 0:
                print("Collision!")
                break

        plt.plot([x[0] for x in data], [x[1] for x in data])

Earth = Object(name="Earth", position=(50.0, 50.0), radius=6.371, mass=5.972e24)
Moon = Object(name="Moon", position=(100.0, 100.0), radius=1.737, mass = 7.347e22)  # position not to real scale
Craft = Object(name="SpaceCraft", position=(49.0, 40.0), radius=1, mass=1.0e4)

Craft.giveMotion(deltaV=8500.0, motionDirection=100, time=130000)
Craft.giveMotion(deltaV=2000.0, motionDirection=90, time=60000)
plt.show(block=True)

How it works
It all boils down to two things:

Creating object like Earth = Object(name="Earth", position=(50.0, 50.0), radius=6.371, mass=5.972e24) with parameters of position on grid (1 unit of grid is 1000km by default but this can be changed too), radius in grid units and mass in kg.
Giving object some deltaV such as Craft.giveMotion(deltaV=8500.0, motionDirection=100, time=130000) obviously it requires Craft = Object(...) to be created in the first place as mentioned in previous point. Parameters here are deltaV in m/s (note that for now acceleration is instantaneous), motionDirection is direction of deltaV in degrees (from current position imagine 360 degree circle around object, so direction is a point on that circle) and finally parameter time is how many seconds after the deltaV push trajectory of the object will be monitored. Subsequent giveMotion() start off from last position of previous giveMotion().

Questions:

Is this a valid algorithm to calculate orbits?
What are the obvious improvements to be made?
I have been considering "timeScale" variable that will optimize calculations, as it might not be necessary to recalculate vectors and positions for every second. Any thoughts on how it should be implemented or is it generally a good idea? (loss of accuracy vs improved performance)

Basically my aim is to start a discussion on the topic and see where it leads. And, if possible, learn (or even better - teach) something new and interesting.
Feel free to experiment!
Try using:
Earth = Object(name="Earth", position=(50.0, 100.0), radius=6.371, mass=5.972e24)
Moon = Object(name="Moon", position=(434.0, 100.0), radius=1.737, mass = 7.347e22)
Craft = Object(name="SpaceCraft", position=(43.0, 100.0), radius=1, mass=1.0e4)

Craft.giveMotion(deltaV=10575.0, motionDirection=180, time=322000)
Craft.giveMotion(deltaV=400.0, motionDirection=180, time=50000)

With two burns - one prograde at Earth orbit and one retrograde at Moon orbit I achieved stable Moon orbit. Are these close to theoreticaly expected values?
Suggested exercise: Try it in 3 burns - stable Earth orbit from Earth surface, prograde burn to reach Moon, retrograde burn to stabilize orbit around Moon. Then try to minimize deltaV.
Note: I plan to update the code with extensive comments for those not familiar with python3 syntax.
Comment: Off the top of my head: consider using a vector for velocity instead of treating speed and direction differently. Where you say "F = m * v" do you mean "F = m*a"? You're assuming the Earth doesn't move because it's so much heavier than asteroid? Consider looking at https://github.com/barrycarter/bcapps/blob/master/bc-grav-sim.pl
Comment: OK. A thought: do the simulation for two real objects (eg, Earth/Moon or Earth/Sun) and compare your results to http://ssd.jpl.nasa.gov/?horizons for accuracy? It won't be perfect because of perturbations by other sources, but it will give you some idea of accuracy?
Comment: A very good idea for self-educating!  Would it be possible to summarise your formulae for those of us who are not familiar with Python syntax?
Comment: Sure, I guess. I will make more extensive comments in the code for those that want to pick it up and summarize the general logic in the question itself.
Comment: You can give motion to any object, including Earth. For test purposes I included only object -> Earth relation in main loop. It can easily be converted that every object relates to all other objects that are created. And every object can have their own motion vector. Reason why I didn't do it - very slow calculations even for 1 object. I hope that scaling time units should help alot but I am still not sure how to do it right.
Comment: Awesome, thanks. That link alone was worth it to start the discussion. So, first step - I will try to re-write the code so that objects check all other objects for gravity force vector. By the way, most pressing issue of time scaling is still here. And it would be interesting to check how results improve or get worse by changing time scale parameter.
Comment: Oh, and F=m*v is really that. Assumption is that by giving motion to the object first of all it goes to absolute halt and by that velocity equals to acceleration. Like instant speed from 0 -> whatever value, and goes on indefinitely with that speed if no other forces act upon the object.
Answer: Let the two bodies involved have masses $m_1, m_2$.  Start with Newton's second law $$F = ma$$ where $a$ is acceleration.  The gravitational force on body 2 from body 1 is given by
$$F_{21} = \frac{G m_1 m_2}{|r_{21}|^3}r_{21}$$
where $r_{21}$ is the relative position vector for the two bodies in question.  The force on body 1 from body two is of course $F_{12}=-F_{21}$ since $r_{12}=-r_{21}$.  If we denote the positions by $(x_1,y_1)$ and $(x_2,y_2)$, then
$$r_{21} = \begin{pmatrix} x_1-x_2 \\ y_1-y_2 \end{pmatrix}.$$
and
$$|r| = \sqrt{(x_1-x_2)^2 + (y_1-y_2)^2}.$$
Then Newton's law $a=F/m$ becomes
\begin{align}
x_1''(t) & = \frac{G m_2 (x_2-x_1)}{|r|^3} \\
y_1''(t) & = \frac{G m_2 (y_2-y_1)}{|r|^3} \\
x_2''(t) & = \frac{G m_1 (x_1-x_2)}{|r|^3} \\
y_2''(t) & = \frac{G m_1 (y_1-y_2)}{|r|^3}.
\end{align}
Together with the initial positions and velocities, this system of ordinary differential equations (ODEs) comprises an initial value problem.  The usual approach is to write this as a first-order system of 8 equations and apply a Runge-Kutta or multistep method to solve them.
If you apply something simple like forward Euler or backward Euler, you will see the Earth spiral out to infinity or in toward the sun, respectively, but that is an effect of the numerical errors.  If you use a more accurate method, like the classical 4th-order Runge-Kutta method, you'll find that it stays close to a true orbit for a while but still eventually spirals inward (as long as the time step is small enough) or goes to infinity (if the time step is too large).  The right approach is to use a symplectic method, which will keep the Earth in the correct orbit -- although its phase will still be off due to numerical errors.
For the 2-body problem it's possible to derive a simpler system by basing your coordinate system around the center of mass.  But I think the formulation above is clearer if this is new to you.
Comment: This will take some time to digest.
Comment: Still digesting. Too many unknown words for me but somehow I feel that at some point I will get there. For now my own algorithm is good enough for things to simply work. But when I will plug in simultaneous motion - I will be forced to get to the literature and read about proper algorithms. Given that limitations of modern hardware are much looser, I can afford to fool around with simple equations. Afraid not for long though.
Comment: Indeed the symplectic methods are by far the most accurate but I think it is difficult for someone with no background in science to implement them. Instead you can use the very simple Euler method along with the Feynman correction. I don't think that you need something more complex than that for self-education purposes.


Is it possible to create a token on the Bitcoin blockchain?

Question: If so, would this token adhere to the same principles as Bitcoin, such as halving events and mining techniques?
Answer: BRC-20 tokens are created on the Bitcoin blockchain and don't follow Bitcoin rules for halving and mining.
You could think of it as a bit like like writing "IOU €50" on a $1 banknote. The US Treasury and The Bureau of Engraving and Printing don't know about or control those IOUs.
Answer: Many different projects have been started as an attempt to bring tokenization on to Bitcoin such as Taro, Counterparty, and RGB. It is worth noting these are not Bitcoin core standards but are projects built on top of existing Bitcoin functionality. Therefore they do not have any implicit tie to Bitcoins proof of work consensus mechanism and also would not automatically inherit the halving cycle of Bitcoin. Even if tokenization was built at the core level, tokens always have rules that are distinctly separate from the rules of the chain's native coin.
Answer: Yes, that's what BRC-20 tokens (aka 'ordinals') are. It sort of jumped the shark though. It was popular for about 3 weeks, but it's difficult to get started for most new users. They are created using ordinal inscriptions, which are a type of script file that can be stored on the Bitcoin blockchain. BRC-20 tokens can be used to represent a variety of assets, such as digital art, collectibles, and gaming items as well, so they might end up competing with NFTs some day.


Region of Operation of MOSFET and current cutoff frequency

Question: The current cut-off frequency for a MOSFET is defined as the frequency at which current gain (ratio of drain to source and gate to source current) is unity. Can we use MOSFET as an amplifier at frequencies higher than current cutoff frequency? If not, why so?
Should we also need to consider MOSFET gain (ratio of Vds and Vgs) while we consider frequencies of operation in MOSFET?
Comment: This puzzles me since a long time: Some manufacturers are using the parasitic input current for specifying something like "current gain" in their data sheets for FETs. For my opinion: Rather misleading.
Comment: Alas it's not only manufacturers that do this, but also [some academics](https://books.google.com/books?id=kEypwK5lUi4C&pg=PA101). So this will probably require a more detailed answer than dismissing it as marketing trick.
Comment: dear Vineesh from which book u refer this explanation. plz tell me
Answer: Disclaimer: the answer below relates to a mosfet transistor used as a voltage amplifier.
Summary
Transition frequency \$f_T\$ is a figure of merit (FOM) of a transistor reflecting both frequency response and gain. The value of \$f_T\$ does not represent unity gain frequency of a transistor, thus, the name "transition frequency" is indeed misleading, imho. Unity gain frequency of a transistor amplifier is driven by input and output RC constants largely (not transition frequency \$f_T\$). The value of mosfet's gate oxide capacitance is a major factor driving frequency response and the value of transconductance \$g_m\$ governs the voltage gain.
Details
1)  "The current cut-off frequency for a MOSFET is defined as the frequency at which current gain (ratio of drain to source and gate to source current) is unity."
This is called transition frequency. See here or [1] below, page 291. 3dB frequency (aka cut-off frequency you mentioned) is a different term. Please, amend the wording, if agree.
2)  To see what drives frequency response of a transistor, let's look at the following example, conventional common source NMOS amplifier:

simulate this circuit – Schematic created using CircuitLab
This amplifier has the following transfer function:
$${A_V}(f) \equiv {{{v_{out}}} \over {{v_{in}}}} =  - {A_{V,LF}} \times {{(1 - j{f \over {{f_z}}})} \over {(1 + j{f \over {{f_{p1}}}})(1 + j{f \over {{f_{p2}}}})}},$$
where \${A_{V,LF}} = {g_m}{R_{load}}\$ is a low frequency gain, \${f_{p1}} = {1 \over {2\pi {R_s}{C_{in}}}}\$ and \${f_{p2}} = {1 \over {2\pi {R_{load}}{C_{out}}}}\$ are poles governing frequency response, and \${f_z} = {{{g_m}} \over {2\pi {C_{gd}}}}\$ is a right-half plane zero,
$$\eqalign{
  & {C_{in}} = {C_{gs}} + {C_{MI}} = {C_{gs}} + {C_{gd}}(1 + {A_{V,LF}}) \approx {C_{gs}} \approx {2 \over 3}{C_{ox}}  \cr
  & {C_{out}} = {C_{MO}} = {C_{gd}}(1 + {1 \over {{A_{V,LF}}}}) \approx {C_{gd}} \cr}. $$
It was assumed that output resistance of the mosfet is much greater than \$R_l\$. Note also that \${C_{gd}} <  < {C_{gs}}\$.
See [1] pages 661-662 for derivation of the formulas.
So, the first pole \$f_{p1}\$ is governed by gate to source capacitance and source resistance (and to a lesser extent by gain through input miller capacitance assuming \${C_{gd}} <  < {C_{gs}}\$, what is usually the case for mosfet in saturation mode).
The second pole \$f_{p2}\$ is governed by value of load capacitance (in this example Miller output capacitance of gate to drain capacitance \$C_{gd}\$) and load resistance.
Now, we see that gate oxide capacitance \$C_{ox}\$(or gate to source capacitance \$C_{gs}\$, which is around 2/3 of the total gate oxide capacitance, whichever you like) is the major factor driving frequency response. The major factor driving low-frequency gain is transconductance \$g_m\$.
3)  In practice we want both high cut-off frequency and high gain. Thus, we want high transconductance and low input capacitance simultaneously. The parameter \${{{g_m}} \over {{C_{ox}}}}\$ would be a proper FOM. Since \$f_t\$ is proportional to \${{{g_m}} \over {{C_{ox}}}}\$ (see below) it became such a FOM.
4)  What is \$f_t\$ and how to boost it?
\$f_t\$ is defined as a short-circuit (small signal gain, strictly speaking) current gain of transistor.
It can be derived that \${f_T} \approx {{{g_m}} \over {2\pi {C_{gs}}}}\$ (see the answer of Vineesh or [1] page 290).
Applying long-channel formula for transconductance it is turned into:
$${f_T} \approx {{{g_m}} \over {2\pi {C_{gs}}}} = {3 \over {4\pi }}{{\mu {V_O}} \over {{L^2}}} \propto {{\mu {V_O}} \over {{L^2}}},$$ where \${V_O} \equiv {v_{GS}} - {V_{TH}}\$ is overdirve voltage and \$\mu \$ is charge carriers mobility.   \$g_m\$ is proportional to \$C_{ox}\$. \$C_{gs}\$ is also proportional to \$C_{ox}\$, thus \$C_{gs}\$ has disappeared (was crossed out).
So, to increase transition frequency:
1) use semiconductor with higher charge carriers mobility (hard to implement). From this, we see that nMOS has higher \$f_t\$ than pMOS due to higher electrons mobility than holes;
2) use higher overdrive voltage to boost \$g_m\$, the drawback is smaller output range;
3) use minimum gate length (the drawback is lower output resistance which may deteriorate gain).
[1]: "CMOS Circuit Design, Layout, and Simulation, 3rd Edition", R. Jacob Baker
Answer: The current gain of the Mosfet as specified in datasheets is actually the short circuit current gain.
The current gain of the above model is given by
$$
i_{L}/i_{i} = -g_{m}/s(C_{gs}+C_{gd})
$$
Therefore the current cutoff frequency \$f_{T}\$ is given by
$$
f_{T} = 1/2\pi(C_{gs}+C_{gd})
$$
Where as the open circuit voltage gain given by the model
$$
v_{O}/v_{in}= -g_{m}/(g_{ds}+sC_{gd})
$$
hence the open circuit cut-off frequency is approximately given by
$$
f = g_{m}/2\pi C_{gd}
$$
In saturation region \$C_{gs} > C_{gd}\$ ,hence short circuit current cutoff frequency is less than open circuit voltage cuttoff frequency ideally.
But these parameters are absolute maximum.Both parameters limit the high frequency operation of the MOSFET. Depending upon the loading conditions the voltage cutoff frequency decreases considerably.So it is easier to mention the current cutoff rather than the voltage cutoff frequency as absolute  maximum rating. Hence you cannot use the MOSFET as an amplifier at frequencies above \$f_{T}\$ since it is the absolute maximum rating.
In RF applications we need to mention one more parameter known as the maximum oscillation frequency.The maximum oscillation frequency,which is defined as the is defined as the frequency at which the
power gain of the transistor is equal to unity under optimum matching conditions for the input and output impedance ,is directly proportional to the Current cutoff frequency \$f_{T}\$.
Just to give an idea,in a standard 0.18\$\mu\$m process the cutoff frequencies \$f_{T}\$range from 50Ghz to 80Ghz.
Hope this clears your doubt.
Comment: But if power gain falls above current cut off frequency, as you mentioned,  then MOSFET can't act as an amplifier. There has to be a net power gain to be an amplifier.
Comment: Yes you are right.I was a little confused earlier about the voltage characteristics but now its clear.I have edited my answer accordingly please have a look.
Comment: Dear Vineesh from which book u refer this explanation plz tell me @firstname.lastname@example.com, thanks


Why is SQL Server Agent not starting?

Question: I just installed my SQL Server 2014 on the top of Windows Server 2012. But after installation SQL Agent is not starting. Can someone tell me like what can I do to solve this? PFA screenshot for the same.
Comment: Possible duplicate of [How to fix error "SQL Server Agent stopped automatically"?](http://stackoverflow.com/questions/29318058/how-to-fix-error-sql-server-agent-stopped-automatically)
Comment: You can read the solution https://stackoverflow.com/questions/29318058/how-to-fix-error-sql-server-agent-stopped-automatically
Answer: It's because you've installed SQL Server Express (indicated by the instance name SQLEXPRESS), SQL Server Agent is not supported in this version, it installs the service, but it does not allow it to run.  You need one of the non-free SQL server editions in order to use SQL Server Agent.
Answer: In case you'are using SQL Server Express, before quiting, I think you should know that SQL Server versions (including Express) offers a system stored procedure named sp_procoption, which allows one to define a user stored procedure name to be executed whenever SQL Server instance is started and lives along your SQL Server service. That user stored procedure can contain your onwn scheduling loop.
<code>exec sp_procoption @ProcName = ['put your procedure name'], @OptionName = 'STARTUP', @OptionValue = [on|off]
</code>
For further reading, I would suggest checking Armando Pratos's excellent article and this SQL Server Online Book

Why is SQL Server Agent not starting?


Animations in sequence

Question: I want to set colors to my tiles in sequence.
This function is called in a for-loop, so its called some times in a very short timewindow.
            tile.setImage(R.drawable.blue);

This is the function:
public void setImage(int resId){

    Animation fadeInAnimation = AnimationUtils.loadAnimation(this.getContext(), R.animator.fadein);
    startAnimation(fadeInAnimation);

    setImageResource(resId);
}

and this is the fadein.xml

<alpha
    android:duration="1000"
    android:fromAlpha="0.0"
    android:interpolator="@android:anim/accelerate_interpolator"
    android:toAlpha="1.0" />

</set>

I want the animation to start only if the animation before it is done.
So I would like the first image to be drawn the first sec and the second image during the second sec, and so on.
BR
Answer: Use AnimationListener especially its method onAnimationEnd(Animation animation)
fadeInAnimation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {

            }

            @Override
            public void onAnimationEnd(Animation animation) {
                // CALL next animation
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });`

Animations in sequence


Do subjective questions that meet SE guidlines have a place on Linguistics.SE?

Question: Created this question as a result of this question titled How to Start a Linguistics Book Club? and the related official SE Guidelines for Subjective Questions.
Comment: http://ux.stackexchange.com/questions/12100/why-shouldnt-we-use-the-word-here-in-a-textlink (applies to "this" too)
Comment: @hippietrail: "here" is not descriptive, question is. That said, fair enough -- is the edited text a better anchorlink? Ironically, you provide "ux.stackexchange.com/questions/12100/..." as the anchorlink text instead of [Why shouldn't we use the word 'here' in a textlink](http://ux.stackexchange.com/questions/12100/why-shouldnt-we-use-the-word-here-in-a-textlink)... :-)
Comment: Yes it's better now and fair call on my bad! But I was giving you a taste of your own medicine too (-;
Answer: So I have two points to make here.
First: I think it's clear that this question could be rephrased to meet the guidelines for subjective questions.  The problem is that it invites opinion (or speculation) over personal experience; other than that I don't think it breaks any of the guidelines.  One suggestion I made in the original thread: Solicit personal experiences on what works and what doesn't in running linguistic discussions for laypeople.  (Perhaps nobody will have personal experiences about running a linguistics book club, but I'm guessing some of us will have experience with running popular linguistic discussions more generally.)
Second: I suggested in the bad stats thread that we should aim to help people with practical goals if we want to strengthen the user community here.  This strikes me as a good example of that: someone has a practical goal that's related to linguistics, they have a question about how to achieve that goal, and we are in a position to give answers.  Good answers will be linguistics-related.  (It would be fine to exclude non-linguistics-related answers like "Put up an ad on Craigslist!" or "Make sure to serve snacks!")
Anyway, I think it is very much in our best interest to find some way of refining or redirecting questions like these rather than simply downvoting and closing.  We want to be a useful resource, and here's a way in which we can be useful (and enlarge our userbase) without breaking any SE guidelines or diluting the purpose of the site.
Comment: +1 @Dan Velleman: Thanks, feel free to edit the question directly if you like, really not going to be the end of the world to me. My guess is at this point if it was agreed that a question like, "Based on personal experiences running linguistic discussions for laypeople, what works, and what doesn't?" should just be a new question; in part because it addresses issues related to people getting offended by comments getting deleted and I don't care if the question is deleted; meaning just delete the question as is, and post a new one that's "approved" by the community.
Comment: Might also add that I'm unable to find anything within your answer that I do not agree with.


40A ssr control 100A main switch

Question: I'm working on a switching device and I'm thinking of switching a hotel room lights + aircon + heater + tv, this is my my project for school. The Main Switch says 100A.. can a solid state relay of 40A sufficient to control that? I'm wondering why others sells 25A magnetic key car switch. Please help
Comment: A 40A switch is not enough to switch 100A, but might be enough to switch whatever's in the room.  You need to start from the load ratings and then decide what size switch you need.  You would not normally control an A/C unit by interrupting the power to it; if you're going to do that then you need to be careful that you don't upset the A/C equipment in any way.
Comment: And if you will have anywhere near 40 A on the SSR -- keep in mind that it needs a serious heat sink. They drop about 2 V. So that means it could be up to 80 W. That's a lot of heat generation.
Comment: I'm wondering how come they are selling 30A keycard switch. any reason to that?
Comment: Not an SSR? Probably using a relay. A 120VAC relay uses about 2 W of power.
Comment: The unit I designed here for true 40A switching uses a combination of a relay AND an SSR. The SSR comes on for 0.1 second, while the relay engages, to protect the relay contacts from arcing. Then, once the relay is fully engaged (at 2 W power), the SSR is turned OFF. The SSR is only used for short moments in order to improve the relay lifetime by protecting the contacts from arcing. So I don't need much heat sinking for the SSR (which uses pairs of SCRs instead -- even better.)
Answer: The size of main fuses is always for protection of the supply chain and is chosen far over the maximum requirements of your local system. In case something goes very wrong with your local circuits the main fuse blows to prevent a supply problem with adjacent users not connected to your circuit.
Example: The mains fuse of your house prevents that in case something goes wrong in your house does not cause a problem in the house of your neighbours.
Now back to the hotelroom situation. Keycards are used in hotels, etc. and are layed out for mostly a little more then the requirements.
So if the hotel keycard has a switching capacity of 30A then an SSR of 40A could handle it as well. But a warning here is relevant. The SSR loses about 2V. Therefore the power dissipation could become 60 or 80W so the use of a large heatsink is needed.
A standard keycard system remains therefore much less expensive then a system with an SST in the power chain.

40A ssr control 100A main switch


Quieter, faster continuous rotation servos

Question: I'm using a couple of continuous rotation servos to drive the wheels on a mobile robot.  One issue I have is that the servos produce a loud, whining sound when in use.  Do higher quality servos exist that make less noise?  It would also be great if the robot could move a bit faster - are speedier servos available?
Comment: Which servos are you using?
Answer: Any standard PMDC motor would work for this, brushed or brushless.
Continuous rotation servos if I recall correctly are basically just a hack.  The typical servo has a radial pot, motor, gearing, and a little controller to get the position right.  Their goal is to provide repeatable, precise control, not be efficient or very fast.  The reason they make so much noise is because you have a tiny, tiny motor spinning a massive step-down transmission.
Using "just a motor" and gearing it down yourself (or with an integrated gear head on the motor) is the best solution.
Answer: If it doesn't have position feedback, it's not a servo.  Continuous rotation "servos" are just gearmotors in the hobby-servo form factor.
So what you want to do is get proper gearmotors to run the wheels.  There are lots to choose from.
Comment: If I recall correctly, based on the PWM you give them they will go forwards/reverse; so they still have a controller of some sort left in them.
Answer: I believe you just need separate(and more powerfull) brushless motors + reductors for this.
This way you can control speed, not spefic angle of each whell.
Answer: The noise comes from the gearbox. You won't reduce this unless you go for a different gearbox design or belt drive.
The motors used in hobby servos are small and light - originally designed for airplanes.
It is easier to make and control a small, low current high speed motor than a big high current one. Hence the design.
There are high torque servos 'Monster truck servos' which can speed up your robot to a degree.
So unless you are prepared to pay BIG bucks for an industrial drive and controller (which might have a brushless motor) with a good gearbox, sorry, its noise you have to put up with.
I use motor car and truck windshield wiper motors on larger projects where I want more oomph. Automotive and BLDC are good next starting points.


Early '90s sci fi anthology episode about a man who is granted wishes, but has to spend eternity working in a mine to pay them off

Question: Looking for an episode from a sci fi anthology series where a man is granted wishes, but has to pay them off by working in a mine forever.
Answer: I don't know about the "sci fi anthology series" you're asking about (was it on radio or television?) but I believe the story is "Something for Nothing" by Robert Sheckley, which was also the answer to the old question Help finding the name of a radio drama about a machine that grants wishes, but turns out to be a credit card.
The story was first published in Galaxy Science Fiction, June 1954, which is available at the Internet Archive. It has been reprinted in a number of anthologies and collections. The X Minus One radio adaptation, which originally aired on April 10, 1957, is available at the Internet Archive and also on YouTube.
A contemporary man receives a mysterious gadget from the future, which seems to be a "wishing machine", but turns out to be a credit card. When the bill comes due and he can't pay, he is sentenced to work it off in the marble quarry:

When he opened them again, he was standing on a bleak plain, facing a range of stubby mountains. A cold wind lashed his face and the sky was the color of steel.
A raggedly dressed man was standing beside him. "Here," the man said and handed Collins a pick.
"What's this?"
"This is a pick," the man said patiently. "And over there is a quarry, where you and I and a number of others will cut marble."
"Marble?"
"Sure. There's always some idiot who wants a palace," the man said with a wry grin. "You can call me Jang. We'll be together for some time."
Collins blinked stupidly. "How long?"
"You work it out," Jang said. "The rate is fifty credits a month
until your debt is paid off."
The pick dropped from Collins' hand. They couldn't do this to him! The Utilization Corporation must realize its mistake by now! They had been at fault, letting the machine slip into the past. Didn't they realize that?
"It's all a mistake!" Collins said.
"No mistake," Jang said."They're very short of labor. Have to go recruiting all over for it. Come on. After the first thousand years you won't mind it."
Collins started to follow Jang toward the quarry. He stopped.
"The first thousand years? I won't live that long!"
"Sure you will," Jang assured him. "You got immortality, didn't you?"
Yes, he had. He had wished for it, just before they took back the machine. Or had they taken back the machine after he wished for it?
Collins remembered something. Strange, but he didn't remember seeing immortality on the bill Flign had showed him.
"How much did they charge me for immortality?" he asked.
Jang looked at him and laughed. "Don't be naive, pal. You should have it figured out by now."
He led Collins toward the quarry. "Naturally, they give that away for nothing."
Comment: Technology to time travel, grant immortality, but they still use manual labour with hand tools to cut marble?
Comment: The story says "The total came to slightly better than eighteen billion Credits". At 50 credits a month, this comes to 30 million years, more or less.
Comment: @Colombo I guess punishment still has to be painful in the future. So it's not so much about earning money than to be punished I guess.
Comment: The anthology was likely a book :-)
Comment: @Colombo Clearly it was one of those "I'm too lazy to do this job myself, so I will go to ridiculous lengths to automate it instead" situations.
Comment: @Colombo They can send the marble from the future when it will finally be quarried back in time to the minute it is needed.
Comment: @columbo tax credits.
Comment: It was on TV, but that is the story exactly, thank you so much!!
Comment: You're welcome! Now I hope somebody will identify the TV show.
Answer: From @user14111's answer I went through Robert Sheckley's contributions on IMDB. He has a writing credit on a 1996 episode "The Utilizer", which seems to be an adaptation of the story "Something for Nothing." TCM has that it aired December 1995 on SyFy but everything else I've seen says December 1996. It doesn't seem to be explicitly part of an anthology.


Is there any way to test if a Players inventory is not full in Minecraft

Question: Is there any way to test if a player's inventory is not full (eg. atleast 1 empty slot anywhere in the inventory, not counting Armor Slots) with command blocks and whatnot?
Comment: If you solved your own question, please post it as an answer rather than editing the question.
Comment: I think it would be possible by checking each individual slot with command blocks and using lots of comparators + AND gates, but that would take forever.
Comment: Well, good to know that it might atleast be possible. Any clue how I would check the slots themselves (ie. what command I would need for each command block?)
Answer: I found /testfor @p {Inventory:[{Slot:0b}]}, which outputs a 1 block signal if there's an item there, and no signal if that slot is empty. This would require 36 command blocks, to check every slot (including the hotbar; 27 to just check the inventory, 40 if you wanted to check armor slots)
Comment: Major flaw with straight up using test for: NOT multiplayer friendly. Also this is very labourous to do.
Comment: Looks like you can also check all slots in one single command, since as you see, the `Inventory` tag accepts an array. I'd assume you can stuff all slots into that array. Not sure if that checks for non-empty or full, though.
Answer: This solution works for 1.14 for sure, I have not tested for 1.13. It can be elaborated on to check the entire inventory in one command; however, in this example I am only checking the hotbar.
<code>/execute if entity @p[nbt={Inventory:[{Slot:0b},{Slot:1b},{Slot:2b},{Slot:3b},{Slot:4b},{Slot:5b},{Slot:6b},{Slot:7b},{Slot:8b}]}] run say Hotbar is not full.
</code>


Do the bike upgrades affect performance?

Question: In Trials Fusion, do the upgrades made to a bike (body and/or wheels) affect performance at all, or are all the upgrades just purely cosmetic? There is the ability to buy new wheels and bodies, but it's not clear if those are just for looks or not.
Answer: Bike customisation does not affect performance in Trials Fusion:
1) There is no indication of improved statistics in the customisation menu. Normally when you get the opportunity to upgrade something in a video game (whether it's a bike, a car, a gun, or something else entirely), you will be presented with a number or a bar of some sort indicating whether it will make a positive or negative effect. In Trials Fusion, there is no such indication. And I don't think Red Lynx would implement 'hidden' upgrades.
2) In Trials Evolution, bike upgrades had no impact on performance. Each bike had its own performance ratings (visible on the bike selection screen), and installing new parts did not change those ratings in any way.
3) If bike upgrades did affect performance, it would result in imbalance. One of the most important aspects of playing Trials is picking the right bike for the level you're playing, and deciding which statistic will be the most important (eg speed vs acceleration vs manoeuvrability etc). If upgrades did affect performance, it would play havoc with the bike selection process (especially since statistics aren't displayed), and would result in players having unfair 'hidden' advantages in leaderboards and multiplayer matches.
In summary: I believe that if bike upgrades did affect performance, this would have been made evident by the developers, either by displaying performance statisitics, or by mentioning it in a menu or manual.
Answer: Yes, the upgrades do affect performance. I own the game and I've done upgrades to the bikes. They do affect performance.
Okay, looks like I made a slight mistake. Thought they did affect performance, but I guess I was just losing my mind. I am really sorry for the confusion. They don't affect performance.
Comment: Can we please get some facts to follow up on this? You are the only  person to say that the upgrades change performance.
Answer: Upgrades are purely cosmetic and do not affect the performance.
Since the game is based on player competition, if the bikes where not the same for everybody, it would be pointless.
Answer: The only real difference I've seen so far is between the Fox Bat and the Roach.
You unlock the Fox Bat when you do the FMX levels. The difference between the two bikes is quite stark as if you apply too much gas from stationary, the bike will flip over and you'll land on your face.
Comment: I was referring to upgrades to the bikes themselves (wheels, body,e tc.), rather than the different bikes.
Answer: As much as I have understood about the game, the upgrades don't seem to affect performance. They really are purely cosmetic!


How is a direct address table different from an array?

Question:
I found this from this PDF (https://web.stanford.edu/class/archive/cs/cs161/cs161.1168/lecture9.pdf)
Answer: The direct access table can be implemented as an array, which means that all operations you are to do to the array must be limited to the what is expected for a direct access table, which in turn is an implementation of a dictionary.
In a direct access table, the index of the array is treated as the integer representation of a key of the dictionary, while an element in the array is the value attached to the key. An empty index in the array means that key of the dictionary is not present. And also, the array must be large enough to be able to store all possible keys of the dictionary, even though in most cases small subset of the keys are being used.
All those requirements above is not necessarily true to all use cases since an array is a general purpose structure for representing group of elements. The index may or may not mean anything, which is entirely dependent on how the array is used.
Answer: As shown in the figure, the pairs key/data are decoupled from the array of links, and this is clearly different from a pure array. Also note that it allows to represent empty slots.
But this data structure is essentially introduced to prepare the next topic: hashing with chaining. It is not really useful in itself.
Answer: An array can be a very simple data structure - although you can have more complex structures for example if you want adding/deleting items at the start or end, or at arbitrary places, fast.
These guys implement a sparse array in a reasonable way. The size requirement is number of possible indices times size of a pointer or index, plus number of used indices times size of array element. But the requirement remains that the set of possible indices must be small(ish).
Why this is called "direct access table" is beyond me, since it is quite obviously an indirect access table.


Embeded Acrobat Reader in Windows 8 Store Application

Question: How can I embed Acrobat Rader in aWindows 8 Store Application. There are some tutorials based on C# and there some related question but I could not find any solution. They all suggest adding a COM element and then selecting Acrobat Reader control from toolbox. I have added Acrobat Reader COM element but it gave me error:
Answer: You cannot do this if you want your application to be certified for distribution on the Windows Store.
COM objects can be used in Windows Store Apps, but they must be distributed with your application package, and they must not use any forbidden API for the Windows Store. This is must likely not the case for the ActiveX control of Acrobat Reader, since it uses (just to mention one example) the OPENFILENAME dialog, which is not allowed in Windows Store.
Edit on April 2013:
Amyuni PDF Creator for WinRT (a commercial library) is currently available as pre-release trial. This library provides a Xaml control for PDF viewing in Xaml-based projects, and it can also be used for PDF-to-HTML5 convertion in WinRT-Javascript projects.  Disclaimer: I currently work as a developer of the library
Answer: Sad to say, but at this time, the only way to read pdf files inside a Windows 8 Store app is to use commercial libraries such as Foxit.


Transit in Hong Kong with one passport and then entering Australia with another

Question: I hold Panamanian and Chilean citizenships. My Australian visa is with the Panamanian passport but I want to book with Cathay Pacific, with a layover in Hong Kong. Panamanians need a transit visa, while Chileans do not. Can I make the transit in Hong Kong with the Chilean passport and then enter Australia with the Panamanian passport? I am traveling from the US (where I currently study and my student visa is on my Panamanian passport too).
Answer: Yes. There's nothing uncommon about this. On the way out, just show your Chilean passport to Cathay staff in the US. There's no immigration control when leaving, so they only care about ID and visa status at your destination and transit points.
On the way back, when leaving Australia, you'll have to show both passports to the airline, as your final destination is the US, and your US visa is in the Panama passport.
Comment: What about the authorities in Hong Kong? They would not care that I was coming from the US and have no American visa in my passport (it is unused since I have it)?
Comment: And thank you for your quick response.....Im just nervous about buying my ticket...thanks
Comment: Where you come from is not important for the airlines. They care about where you go, and whether you have the legal status to go there. Which is why, on your way back, you'll have to show both passports in Australia, and your Panama passport in HK.
Answer: For the immigration officer:
As long as you use the same passport to enter then exit the same country, there's no issue
For the airline:
You have to show that you have the visa needed for your trip, so you might have to show them both passports


Can the fee be 10 times bigger than the amount that was sent?

Question: I don't understand one thing : If I get paid an amount of 0.000055 BTC ore more, how come the fee is 0.0005 ? The fee is ten times bigger than the amount I was paid?
Answer: The tansaction fee is based mostly on the transaction size (in kilobytes), not its amount (in BTC).
Even more: the bitcoin protocol is quite unfriendly to small transactions to prevent spamming the network. If the transaction output is larger then 0.1 BTC, then the fee could be leveraged (more on fee generation algorithm here)
Answer: This is to avoid Spamming transactions that would take a lot of space in the block chain.
If you want spend this coins you should wait until transaction fees will be decreased by future updates.
Answer: Yes. Similarly if you used a courier to send a package containing $0.01, you could find that it would cost more to send it then the value of the contents.


solana-test-validator looses history on restart

Question: I am running a solana-test-validator locally. When shutting it down and restarting it, the balances for accounts persist - so I am sure that not everything was reset. However, transactions which were sent to such account disappear from the transaction history at https://explorer.solana.com/ (connected to localhost, but also with a general RPC check). I was assuming, that the history would be kept. --limit-ledger-size might not be related here, because it's also happening with the very first transactions.
Answer: <code>--limit-ledger-size</code> is absolutely crucial here. It tells how many shreds to keep around, and defaults to 10k. Since every block will have at least one vote, that means every 400ms block will have at least one shred to keep around (maybe more for erasure shreds, I'm not sure if those are kept around).
At 10k shreds, and 400ms blocks, you're looking at a maximum of one hour of data kept around (10000 * .4s = 4000s). It might be even less if there are lots of transactions in the blocks. All that to say, feel free to increase the number of shreds by 10x or 100x!


Error while load genymotion in debian jessie

Question: i got this error:
./genymotion: error while loading shared libraries: libQtScript.so.4: cannot open shared object file: No such file or directory
Comment: Please post the code you've written, it's usually not possible to answer a question without seeing your code.
Answer: you are trying to run a binary that is dynamically linked against a library that is not present on your system.
Install the library package that provides the missing library:
<code> apt-file search libQtScript.so.4
</code>
Answer: If you're using debian jessie you should install this:
<code>apt-get install libqtwebkit4 libqt4-script libqt4-svg libqt4-sql
</code>
Here we have a full tutorial:
http://tukitanotes.blogspot.com.br/2014/12/genymotion-on-debian-jessie.html


my Samsung phone says it doesn't have a rooting system, in laymens terms, how do I fix it

Question: I installed a memory booster/ security device on my Samsung recently. I have always wondered if I actually need all this hardware and apps in my phone. Now it tells me I can uninstall some apps , when I go to do it my phone says unable to no root system. What do I do?
Comment: First I would be highly suspicious of the program, as "memory booster" sounds like crap - second, it's asking for root privileges, which you are unable to grant unless you have rooted your device - which if you post the exact model, or just search "root *exact model name*", you should be able to get good instructions. Again, I would NOT recommend doing it for this app as it sounds fishy, and will likely make things go badly.
Answer: Firstly, I agree with @user2813274. You should be very careful about what you try to uninstall as things can go badly wrong.
To answer your question of what to do:
You need to grant the app root privileges.
To uninstall system apps root access is required, which is in basic terms, elevated permissions. The app you have installed is unable to remove some of the apps because they are system apps and it lacks the necessary permissions to do so.
If you need help rooting your device I would check on XDA Developers for instructions specific to your device.


How I could arrange these better?

Question: I was wondering how I could arrange these better? Currently I have sections 1-3 and when you select one or multiple it give you new row of check boxes. I think this is quick way to solve problem but exhausting on UI.
Answer: If the number of top-level sections is three, or at least reasonably small, you can use a different layout:

The subsections will be rendered under the corresponding top-level section, so it expresses the hierarchy clearer.
Answer: Use the Section 1, Section 2 & Section 3 as in the side sticky bar, and further check boxes can be viewed like tags format based on which the content can be filter or displayed. Please check the attachment for reference. - > https://i.stack.imgur.com/ChSXu.png
Answer: If I understand your problem correctly, you have a couple of items in the highest order and each of them has some subitems. And you need to make it visually unambiguous which item of the highest order is "opened".
What about some background colour hinting, like this?

download bmml source – Wireframes created with Balsamiq Mockups

How I could arrange these better?


When exactly does velocity increase or decrease on an acceleration time graph?

Question: How does the acceleration time graph show if and object is speeding up or slowing down?
Is it possible to find the answer without any deep calculations? If yes then how?
Like how can I find the instantaneous velocity? Using accelration time graph?, and how can I show if the object is accelerating? Cause the graph just shows me if my delta velocity exists it doesn't tell me if my velocity is going to zero of something else!
Comment: I'm a high school student, but I have read a bit of collage physics but math only for my level of grade 10...
Comment: https://www.khanacademy.org/science/physics/one-dimensional-motion/acceleration-tutorial/a/what-are-acceleration-vs-time-graphs
Comment: What is your level of familiarity with physics and/or mathematics? This could help the person answering your query.
Answer: It depends on the instantaneous velocity. If the acceleration has the opposite sign then the velocity, the speed will be getting slower at a given time, and if the acceleration is the same sign as the velocity at that time, the speed will be getting faster. Of course, if the acceleration is $0$, the velocity isn't changing. So, just the acceleration in the graph won't tell you; you also need to know the velocity.


I need to emulate the shadows and embossing effects on a picture to my vector design

Question: I am designing a menu for a sushi bar and i am inspired by their wall patterns and i wanted to emulate the pattern to the front and back cover of the menu. I redid the shapes on illustrator but i am having a hard time bringing the vector to life. I want to be able to make the vector look 3d and for the shadows and lighting to show. I am new 2 illustrator and im not sure if its possible. Or would i have to design the vector in another program? like cinema 4d or photoshop? thanks alot for the help guys!
here are the pictures.
Comment: Try to make a [Gradient mesh](https://helpx.adobe.com/illustrator/using/meshes.html)
Comment: although for just starting in Illustrator, that pattern is impressive!  Complex shadow effects are still better done in Photoshop.
Answer: as a quick play, I took your image of the wall, cropped it down, and applied it as a "soft light" overlay of your dark blue color:

This was in Photoshop, probably your best/easiest way to replicate without pulling your hair out.  Since the wall panels are, well, panels, you could crop down the image to one tile and use it as a repeating image to make the background, or just use something similar to what is above.  The different angles on the panels make for a very pleasing background, IMHO.


Can't see "Insert image" button in Gmail when composing a mail

Question: When I'm composing a mail in Gmail I want to insert an image directly in the mail's body, but there is no "Insert image" button at the top. How can I configure it to be visible?
Comment: I'm voting to close this question because it's obsolete. The option to add images was graduated from labs several years ago. See the article from Gmail Help [Send attachments with your Gmail message](https://support.google.com/mail/answer/6584?hl=en). Related official announcement (October, 2012) [Introducing the new compose in Gmail](https://gmail.googleblog.com/2012/10/introducing-new-compose-in-gmail.html)
Answer: There are two ways to insert an image in the body of the mail:

drag-and-drop it from its folder to the desired position in the message (depending on your browser, it might or might not work);
enable the Insert image feature from the mail settings and click on the Insert image button (this option requires that the email is composed using Rich formatting).
← new look
← old look

To enable "Insert image":

Go to Settings
Click on the Labs tab
Search for Inserting images feature
Click on the Enable option
Click Save Changes at the bottom of the page
Answer: Indeed, by default there is no button:

If you want to insert an image from your computer to the body of your email, use drag-and-drop from your desktop (or file manager) to your web browser.
This drag-and-drop uses HTML5 so it will not work on old browsers.
Alternatively, you can enable the button as described by Alex, but it is a Labs feature, so it "may change, break or disappear at any time".
I guess Google just wants us to become familiar with HTML5 drag-and-drop.
Comment: Where did you get there's no button indeed?
Comment: @crucifiedsoul: See screenshot. It depends on the user's settings, and it might also depend on whether you have old look/new look.


Implementability of a (abstract) data structure/type?

Question:
Do people consider the implementability of a (abstract) data
structure or a data type, just like people do for
implementability/computability of an algorithm? By implementability, I mean if a (abstract) data
structure/type can be implemented on a real computer or abstract computer model.
Does the implementability of a (abstract) data structure/type depend on and only on

the computability of each of its operations implemented as algorithms, and
whether the space it requires to store each value is limited?

Does the implementability of a (abstract) data structure/type depend on in which
programming language it is implemented?
Does it matter if a programming language in which it is planned to
be implemented is a imperative or functional language? In other
words, are the (abstract) data structures/types that can be implemented by
an imperative programming language and the (abstract) data
structures/types that can be implemented by a functional languages
the same?
why some data structures are called "functional data structures", and even there are some books for it (e.g. https://www.cs.cmu.edu/~rwh/theses/okasaki.pdf). Are "functional data structures" not implemented or introduced in imperative languages? Why  need to distinguish between (imperative?) data structures and functional data structures?
Comment: What do you mean by implementability?  What makes you think that people consider the implementability of an algorithm?  Actually, I can't tell what you are talking about or what you are asking.  Why don't you tell us where you ran across the term "implementability", what you mean by it (give us a definition and/or example), and what research you have done?  Every data structure I've ever seen can be implemented: its specification comes with pseudocode that tells you how to implement it.
Comment: What do you define as implementability? Also, have you considered that the operations of a data structure/type are algorithms?
Comment: You have been asking for long enough to have learned by now: only one question per post, please. I count seven question in this post. (Also, I wonder when you'll pick up on me editing away your "thanks" clause. It's unncessary and generally discouraged on SE; just upvote and accept to show your thanks.)
Comment: On a *real* computer, almost nothing can be implemented since they are finite automata. If you virtually extend them to be Turing-equivalent, you are left with the usual notion of computability. Hardness of implementation is a subjective criterion. So I truly don't get where this question can possibly lead.
Comment: @D.W. I'm assuming by implementability Tim means how easy would it be to implement this into a programming language: such as in the sense that linked-list are easier to implement than Red-Black Trees. But obliviously what would depend on what features **XYZ** language has.
Comment: @SpencerWieczorek: thanks. by implenetability, I mean something like computability, i.e. whether a abastract data structure/type can be implemented in a real computer or a abstract computer model. But I am also interested in "how easy would it be to implement", which I think assumes it is implementable?
Comment: @ZeroUltimax: (1) "What do you define as implementability?" Added a sentence at the end of my first part.  (2) "Also, have you considered that the operations of a data structure/type are algorithms?" see the first bullet in the second part.
Comment: @Raphael "On a real computer, almost nothing can be implemented since they are finite automata." (1) by "finite automata", do you mean finite state machine? (2) If that is true, why can we implement so many algorithms on real computers?
Answer: As I am really not sure how you define implementability, I will guess that you think of complexity of an ADT. And when I say complexity I mean time and space complexity of its operations and space complexity of the values it stores during its lifetime.
People do care that the operations are computable and preferably with low time and space overhead. Usually, there is not a single best implementation of an ADT; take a look at various implementations of a queue in a multithreaded setting. You end up with the one you assume will work best for your particular problem.
The design of a programming language can significantly influence the way ADT is implemented. For example, support for infinite streams comes built-in in Haskell, but in, say Java, you have to implement such an ADT on top of the primitives Java provides, which can be time consuming and slower than in Haskell performance wise.
Comment: Thanks. (1) What I mean by "implementability" is whether an ADT can be implemented or not. i do not assume it can be implemented, and therefore I didn't ask the complexity of implementing it although I am also interested in it. (2) In the sense of "implementability" in (1), I wonder if a imperative langauge and a functional language can implement the same set of ADTs?
Comment: Well, I would define implementability as computability. Efficient computability would then be implementability plus low space and time complexities of its operations and data. Both general purpose imperative and functional programming languages are Turing-complete so they can carry the same computations, just in a different way.
Comment: Then i would wonder why some data structures are called "functional data structures", and even there are some books for it (e.g. https://www.cs.cmu.edu/~rwh/theses/okasaki.pdf). Are "functional data structures" not implemented or introduced in imperative languages? Why  need to distinguish between (imperative?) data structures and functional data structures?
Comment: This book basically gives you the answer to your last bullet. Among some other things, he shows how to implement common ADTs with a functional programming language, and especially if one has lazy evaluation on his disposal. That is where the terminology comes from. Also, I would differentiate between ADT and functional/imperative data structure: note the "abstract" in ADT.


How to find remainder of a very large number when divisor is 17?

Question: How to find the remainder when $2^{2015}$ is divided by $17$?
I tried dividing $2,4,8,16$ etc by $17$ and finding the remainder in each case to form some particular sequence but failed can someone help and please explain in a very simple language?
Comment: You can use Fermat's little theorem and reduce the exponent modulo $16$. You get $2^{15}$. Moreover, since $2^{16}=1$ modulo $17$, the answer is just the inverse of $2$ modulo $17$, and this is $9$.
Comment: Hint: $2^4\equiv -1\pmod{17}$.
Comment: It's well worth learning, if you want to answer this type of question.
Comment: I assume you mean $2^{2015}$, correct?
Comment: I dont know fermat's little theorem
Answer: The prime $17$ is fairly special, it is nearly a power of $2$. Specifically, $2^4\equiv -1\pmod{17}$. Now $2012=(4)(503)$, so $2^{2012}\equiv -1\pmod{17}$, and therefore $2^{2015}\equiv -8\equiv 9\pmod{17}$.
Added: It is now clear that OP is not familiar with "arithmetic modulo $m$." There are two alternatives. The right one is to devlop the basics, since they will continue to be useful. Or else one can find an alternate procedure. We will do that. It will be somewhat ugly.
Note that $2^4=(-1+17)$. So $2^{2012}=(2^4)^{503}=(-1+17)^{503}$. Imagine expanding using the binomial theorem. We get
$$(-1+17)^{503}=(-1)^{503}+\binom{503}{1}(-1)^{502}(17)+\cdots.$$
The important thing to notice is that all the terms after $(-1)^{503}$ are divisible by $17$.
So $(-1+17)^{503}$ is $1$ less than a multiple of $17$. Thus $2^{2012}=17k+16$ for some integer $k$.
It follows that $2^{2015}=8(17k+16)=17(8k+7)+9$. So $2^{2015}$ is $9$ more than a multiple of $17$. Thus the remainder when we divide $2^{2015}$ by $17$ is $9$.
Another way: Alternately, we can compute the remainders when $2^0$, $2^1$, $2^2$, and so on are divided by $17$. We are looking for a pattern.
The remainders are $1, 2,4,8,16,15,13, 9, 1, 2, 4, \dots$. One needs to show that the pattern persists. After one has done that, it becomes clear that the remainder of $2^{2016}$ is $1$, so the remainder of $2^{2015}$ is the entry "before" $1$, which is $9$.
Comment: We write $a\equiv b\pmod{m}$ if $m$ divides $a-b$.  But if you are not familiar with modular notation, maybe I should write a different version of the answer. It will take some time, say $15$ minutes.
Comment: @Raghav: You are welcome.
Comment: What is meaning of mod 17?
Comment: +1. Very nicely explained according to the level of the OP!
Answer: Use Little Fermat:
$$2^{16}\equiv 1\mod17,\enspace\text{hence}\enspace2^{2015}\equiv2^{2015\bmod16}=2^{15}=2^{-1}=9\mod 17.$$


displaying restaurants nearby a user location within 5 kilometers in Django

Question: Good morning Everyone,
I would like to display restaurants within 5 kilometers in using  google maps api , How could I do it?
I have done the latitudes and longitudes calculs with haversine. But i don't know how rendering the result in django.
Thanks
Answer: You don't really need django here, what you're looking for can be done using Google maps API and a map provider (Like Google maps) or Openstreetmap through Leaflet JS.
This is all mostly done with Javascript in a template.
There is a Python version of Leaflet, named folium, if you really want to stick with Python. Not sure you can do everything, as I'm not that familiar with it.


Why does the term "counsel" typically refer to barristers rather than solicitors?

Question: It seems arbitrary that it seems to conventionally refer to one rather than the other, but is actually even more confusing that it refers to barristers rather than solicitors when one typically seeks advice from a solicitor by consulting them for their opinion of the legal position, and not from a barrister. By the time to instruct a barrister to appear in court on one's behalf, it seems that one is largely clear on one's position already and has rather to instruct the barrister on what they wish for them to represent to the court, rather than to seek their counsel. So, what is the basis for this nomenclatural convention?
Answer: The use of the word counsel for barristers has a long history. It was used in England before the modern legal profession developed.
Baker, Counsellors and barristers: an historical study (1969) traces homo consiliarius back to the 13th century plea rolls:

The sum of [a pleader or counsellor's] functions may be termed "counselling" in its widest sense, and the subject of the present study must be what the plea rolls call homo consiliarius, the counsellor. Even this compendious name can mislead. It eventually became synonymous with "barrister," in the sense of "jurisconsult," while some of the counselling came in fact to be done by attorneys and solicitors.

Sense 8(a) of counsel (n.) in the OED ("A body of legal advisers, engaged in the direction or conduct of a cause") is dated back to the Confessio Amantis (1393):

Help, that I hadde counseil here
Upon the trouthe of my matere.

Sense 8(b) ("A single legal adviser; a counsellor-at-law, advocate, or barrister") is first quoted in 1709, but seems also to cover sense 8(a)'s quotation of Greene's coney-catching pamphlets (1591), by distinguishing between counsel and attorney:

[He] hath his mind so full of cares to see his counsell and to plie his Atorney.

As barristers came to replace the serjeants at law, the association of counsel with barristers may have become entrenched with the appointment of Sir Francis Bacon as the first King's Counsel (1603). According to Holdsworth, A history of English law (1924), vol 6, p 472:

It soon became clear that the king's attorney and solicitor could not by themselves do all the work which their office imposed upon them. It is to this cause that we must ascribe the rise of a body of "king's learned counsel," who are the ancestors of our modern king's counsel. It would seem from D'Ewes that a body of persons so designated was known at the very beginning of Elizabeth's reign [1558 – 1603].
Answer: It doesn't
Counsel means a lawyer running a case in court. In jurisdictions with a solicitor-barrister split, these are most often barristers, however, the term is not exclusive to them. In a lower court case being run by a solicitor they could be called counsel, however, it's far more likely they would be referred to by name.
American usage is the same - a lawyer in court is a counsel or councillor.
Comment: I don't know about that. Chambers casually refer to their barristers as "counsel" as in "instructing counsel," or "feel free to put the inquiry in an email and I'd be happy to relay it to counsel for you." etc
Comment: https://en.wikipedia.org/wiki/Counsel#cite_ref-EB1911_1-0 - "The legal system in England uses the term counsel as an approximate synonym for a barrister-at-law, but not for a solicitor, and may apply it to mean either a single person who pleads a cause, or collectively, the body of barristers engaged in a case." - "It is customary to use the third person when addressing a barrister instructed on a case: "Counsel is asked to advise" rather than "You are asked to advise"."
Comment: In American usage, "counsel" is a term that emphasizes the role of an attorney outside of representation in court. Indeed, the Model Rules of Professional Conduct distinguish between a lawyer as an advocate before tribunals and a lawyer as counsel outside of court. I would have *a priori* expected the term "counsel" to be associated with solicitors rather than barristers as the term in American English legal usage is mostly applied to work by U.S. attorneys that is done mostly by solicitors in England.


Expired Passport has expired USA visa but applying for B2 on new passport and dont have old passport physically

Question: Do I need to mention that I had been to USA as a minor (with expired passport and visa details) on the DS 160?
If yes, is it okay to appear for B2 visa not having the expired passport but only a printed proof of the visa? I have all the details of my old passport and visa with me but it is not in the country I am residing in currently. Will I face any issues in the visa interview?
Answer: You must answer the DS 160 questions accurately. The consular officers have access to electronic records of travel into and out of the USA as well as records of visa approvals and refusals. It's highly unlikely that you will even be asked to produce old passport(s). I have never been asked. And if asked, just tell the officer why you don't have it.


RapidIO packet filtering in Linux

Question: I was wondering if there is support in Linux Kernel for RapidIO packets filtering, something similar to iptables, but based on RapidIO header?
Answer: It appears to be supported. I found this text that shows how to enable the features within the Linux Kernel:
CONFIG_RAPIDIO_DMA_ENGINE:

Say Y here if you want to use DMA Engine frameork for RapidIO data
transfers to/from target RIO devices. RapidIO uses NREAD and
NWRITE (NWRITE_R, SWRITE) requests to transfer data between local
memory and memory on remote target device. You need a DMA controller
capable to perform data transfers to/from RapidIO.

If you are unsure about this, say Y here.

Symbol: RAPIDIO_DMA_ENGINE [=n]
Type : boolean
Prompt: DMA Engine support for RapidIO
Defined at drivers/rapidio/Kconfig:25
Depends on: RAPIDIO [=y]
Location:
-> Bus options (PCI etc.)
-> RapidIO support (RAPIDIO [=y])
Selects: DMADEVICES [=y] && DMA_ENGINE [=y]

Additionally on kernel.org the feature RapidIO is discussed here and here.
Finally I found a presentation from 2005 Linux Symposium (Vol. 2 - Ottawa, CA) where there was a presentation titled: RapidIO for Linux. In this PDF on page 43 of the PDF (actually page # 35 in the docs) is an abstract from that presentation which discusses RapidIO support.
References

http://lkft.sirrow.info/?p=50
https://www.kernel.org/doc/mirror/ols2005v2.pdf

RapidIO packet filtering in Linux


Spherical harmonics filtering

Question: Consider a signal $U$ defined on the 2-sphere that is expressed as the product of two functions $A,B$, or
$$
\begin{aligned}
U(\theta,\phi) &= \sum_{n=0}^{\infty}\sum_{m=-n}^{n}u_{nm}Y_n^m(\theta,\phi)\\
&= \left[\sum_{n'=0}^{\infty}\sum_{m'=-n'}^{n'}a_{n'm'}Y_{n'}^{m'}(\theta,\phi)\right]\cdot\left[\sum_{n''=0}^{\infty}\sum_{m''=-n''}^{n''}b_{n''m''}Y_{n''}^{m''}(\theta,\phi)\right],
\end{aligned}
$$
where the coefficients $a_{nm},b_{nm}$ are known. Now, imagine my signal $A$ is filtered, e.g. $a_{nm}\rightarrow a_{nm} h_{nm}$. Is there a modification of any kind that can be performed on the signal $B$, for instance some kind of compensating filter $b_{nm} \rightarrow b_{nm} k_{nm}$ to retain the same value of $U$? If so, can we derive an expression for the filter coefficients $k_{nm}$? In a strict Fourier basis, this is trivial, but the spherical harmonics add quite a bit of complexity to this problem unfortunately.
Answer: The product of spherical functions can be expanded to series of spherical functions again. It is usually done with Wigner 3-j symbols or Clebsch-Gordan coefficients (formulas there are for complex spherical functions, but one can derive from them real-valued ones). This will give you an infinite linear system on coefficients $b_{mn}$. However, you can trim your expansion at some azimuthal number and solve a finite system

Spherical harmonics filtering


Why Didn't Benjamin Linus Enter the Church?

Question: In the series finale of Lost, why didn't Ben enter the church with the rest of the group? It was clear he had already fulfilled his tasks with Hurley as his "No 2" when Hurley was in charge of the island. Was there any explained reason as to why Ben decided not to go in? In-or-out-of universe?
Answer: Because he didn't feel he deserved the life he was beginning to experience.
To better explain:
My interpretation to LOST's ending, particularity the flash sideways, relies on the  concept of the Island's "Heart" (life, death, and rebirth) with death being a transitional plane between one life time and the next.

Christian Shephard: This is a place that you... that you all made
together so that you could find one another. The most important part
of your life was the time that you spent with these people on that
island. That's why all of you are here. Nobody does it alone, Jack.
You needed all of them, and they needed you.
Jack Shephard: For what?
Christian Shephard : To remember. And to... let go.
Jack Shephard: Kate... She said we were leaving.
Christian Shephard: Not leaving. No. Moving on.

I believe the flashsidesways allowed the characters to glimpse/briefly experience the upcoming 2004 of the next timeline, where one group of people (variable set) had to remember the past in order to "move on" to the next time line, and in which they didn't have to directly deal with the Island [again], marking a sign of "spiritual progress".
Even though before he died (epilogue) he went on to help Hugo & Walt, Ben could not accept the life he was experiencing, because what he had done to Danielle and Alex. We may presume like some of the other characters that also did not move on, that he would have to face the Island again in the next go around, in attempts to do better.
As Jacob said, "It only ends once, everything that happens before that just progress."
As long as there is an Island with it's heart in tact, humanity can continuously spiritually progress and be reincarnated through the Island.

From Executive Producers Damien Lindeloff & Carlton Cuse explaining that the characters were alive until any given one had died.
On whether the characters were actually dead the whole time (Since the time the plane crashed): "No, no, no. They were not dead the whole time," Cuse said definitively, adding that he believes that some footage they showed at the very end of the series lead to much of the misunderstanding among fans.
"At the end of the series finale, [an ABC exec] thought it would be good to have a buffer between when you have the end of the show and when they cut to say, a Clorox commercial," Cuse explained. "We didn't have a lot of extra footage lying around, but we had footage of the plane wreckage on the beach," which they shot when the plane needed to be moved or it would have been washed out to sea. "We thought, let's put those shots at the end of the show and it will be a little buffer and lull. And when people saw the footage of the plane with no survivors, it exacerbated the problem."
But the characters definitely survived the plane crash and really were on a very real island. At the very end of the series, though? Yep, they were all dead when they met up in heaven for the final "church" scene.
On what the finale was all about: Carlton explained: "Very early on we had decided that even though Lost is a show about people on the island, really, metaphorically, it was about people who were lost and searching for meaning and purpose in their lives. And because of that, we felt the ending really had to be spiritual, and one that talks about destiny. We would have long discourses about the nature of the show, for many years, and we decided it needed to mean something to us and our belief system and the characters and how all of us are here to lift each other up in our lives." (Hence, the whole brilliang "Constant" concept. Swoon x infinity, Desmond and Penny.)
Damon added: "For us, one of the ongoing conversations with the audience and there was a very early perception, was that the island was purgatory and we were always out there saying 'It's not purgatory, this is real, we're not going to Sixth Sense you.' And we felt it too that the show had to become sort of meta in this way. And so the writers said, 'Obviously, there are all these mysteries. But what if we answered a mystery that was never asked, what's the meaning of life and what happens when you die?'"
Damon added that the idea for the "Flash Sideways" world came about between the planning of seasons four and five because "We were out of flashbacks and we were done with flash forwards. So we started to think about, what if we sort of Trojan horsed in a paradoxical sideways storyline?"
Comment: Or maybe Ben took that Dharma Truck and went back to Island to rule it, because you know that's Benjamin Linus. :D
Comment: No, because the FS was characters meeting "after" death and the "epilogue" was still the same timeline the characters experienced before all of them had eventually died. It's just Jack experiences the FS first, because he dies before some of the others. In other words, despite what Ben does with Hugo and Walt, he still didn't think he deserved it. I've added a few links to better support these ideas from LOSTPEDIA. –