Is it possible to erase a car's "identity" beyond forensic examination?

Question: Suppose you don't want anyone to know where your car comes from, who's owned it before and even where it was made. Is it possible to make this car "unidentifiable" even after thorough forensic examination? If yes, what can be done, in terms of changing plates, erasing registers, chassis, etc, to achieve this goal?
Comment: First uninstall the Bluetooth gps device. Then ask the fbi to expunge the records from their file system. Take your title to a metal recycling plant and sell the car for scrap. No one will ever know.
Answer: Chopshop Car
A Ford body will always be a Ford body and even the year model can be worked out from it. A BMW engine is still a BMW engine and this can be worked out from the design.
With a chopshop car, you change all the bits with parts from other cars so whilst they tell it's a Ford body, nothing else is Ford. Once the certification plates are removed and the engine number is gone, they'd be down to trying to trace parts which gets awfully difficult.
Answer: A large part of this question depends on the model of the Car
In most cases origin and ownership of a car can be obscured by erasing the VIN number which is usually placed on various parts of the car.
It is pretty much impossible to erase who manufactured the car. First of all, most models can be easily traced back to a company of origin and likely factory by appearance alone. The materials in the car can be used to identify factory of origin right down to the metals in the engine (if they cared to look that far). You could obscure this to some extent by replacing parts from different suppliers but to what end really, at some point you've become the manufacturer.
Answer: Assuming you have a factory-built car, and haven't made severe body alterations, the answer is pretty much no. As mentioned, not only will the manufacturer and model be obvious to a regular car buff, they'll know where it was made, because most factories tend to specialize. For instance, suppose your vehicle is an F-150, one of the most common pickups in North America. It's either from the Kansas City Assembly Plant or the River Rouge Complex in Dearborn.
Then, there's the vehicle VIN, typically found engraved in assorted locations on the vehicle, including places that require the removal of major components such as the engine or in the case of the F-150, the cargo bed in order to access. And in some cases it's stamped into metal such that you can't sand it down to remove it without making a hole right through the component.
Next, serial numbers on parts. Again, unless you've replaced everything, they will be recorded somewhere
Then, there's another practical issue: how do you drive it? Car registration and insurance requires a vehicle's VIN. Sure, you might go through all the effort of creating a non-traceable vehicle....but you're not going to be driving it anywhere without being pulled over by the first traffic cop you happen to drive by.
Answer: Identifiability depends not only on the car, but also on the records.  If the VIN and engine number are sanded off and there's no license plates on the car, no registration card in the glovebox, how would someone match it to a record?  If it has identifying dents and scratches, and you have a photo of the car you're looking for, you might be able to match it.  The previous owner, if he saw it, might be able to point it out.  If it has distinguishing features like bumper stickers, people from the same town as the owner might recognize it.  If it has major repairs, you might be able to ask around at the repair shops in the town to see if anyone remembers doing the work.  If it is stolen and the owner has recently filed a report, the police might look up the report and discover the match.
But basically, if you are far from the place where the car was obtained, and there's no recent police report specifically describing it, and if you have removed the easy forms of identification, it may be impossible to trace.  Or at least practically impossible, such that no one can or will make the effort.
Answer: The one and only way to do this is to build every aspect of the car — every nut, every bolt, every stitch of fabric, every mole of glass, everything — 100% custom in your own garage.  Why?
Because you can track bolts, glass, paint, parts, assemblies... even if you remove the model numbers, serial numbers, registration numbers, from every fuse, plastic part, bulb, etc., you'd always have something you can trace.
Which is a long way of saying, no, it can't be done.


How can I change the sentence from active to the passive form?

Question: Active: Alastair arranged to take Kathy to the station.
Passive: Kathy was arranged to be taken to the station by Alastair.
This sentence I read is a bit awkward., but I am not sure, could you explain it to me?
Comment: Your suggestion won't work because the past participial "was arranged" cannot be used here with a proper name. Try: "It was arranged by Alistair to take Kathy to the station".
Comment: 'to take Kathy to the station was arranged by Alastair'
Comment: @Kyamond No: your suggested sentence is ungrammatical.
Comment: @BillJ Huh? How come?
Answer: If the active sentence was simply "Alastair arranged it", then the passive voice would be "It was arranged by Alastair".
So, the passive voice with the full detail would be:

It was arranged by Alastair for Kathy to be taken to the station.

It doesn't matter that Alastair still appears before Kathy in the sentence - she is just part of the arrangement.
You could say "It was arranged for Kathy to be taken to the station by Alastair", but it would sound like Alastair is the one taking her to the station, not the one making the arrangement.
Comment: +1 Another slightly awkward possibility is "The taking of Kathy to the station was arranged by Alastair".  This at least excuses Alistair from having taken her personally.   If he did take her, then the *arrangement* is probably redundant anyway. Then it could simply be "Kathy was taken to the station by Alistair".


KCL Equation question

Question: Hi I was wondering why the i_A is negative in the answer in the photo, it was the only one that ended up not being right when I did the KCL on my own, what would have been my mistake as to why I ended up with a positive instead?
Comment: Easiest way to do these is to just write a sum of all the outward directed currents on one side of the equation and a sum of all the inward directed currents on the other side. Then re-arrange as pleases you.
Comment: Don't get confused when it comes to signs. The signs before a current or voltage in a KVL/KCL eqation don't say anything about the direction in which the current is travelling for real. The direction of the arrows can be chosen randomly. They serve the purpose to define the direction for your symbolic calculations once to avoid any confusion later.
Answer: Because, as drawn, \$ i_A\$ is the only current leaving node 2. All the others are inbound.
Answer: Suggestion
The first thing I do before attempting to analyze a circuit is to redraw that circuit. The process of just doing it helps me think and gather up a few details that I may not notice so easily, just staring at someone's depiction. But I can often help the readability, too, which improves understanding and reduces chances for mistakes, later.
It takes lots of practice to accumulate a good sense about it. But that practice is well worth your time.
You should use the built-in schematic editor here. It will add part numbers and this is very important for saving time and confusion when communicating in comments or in answers. In your specific case, the values of the resistors can be used to identify them. But in general, you should assign separate designations as it won't always be the case that the values are all different from each other.
And finally, keep in mind that you get to call one node "ground." If you select a really convenient one, it can greatly simplify the analysis and reduce chances for mistakes, as well. (This doesn't always have to be the obvious choice or the one that the writer chose. You can move it to a different location if that helps your analysis.)
Redrawn Schematic

simulate this circuit – Schematic created using CircuitLab
Note that node 2 is missing? It's not needed.
KCL Analysis
There is only one KCL equation:
$$\overbrace{\frac{V_1}{R_1}+\frac{V_1}{R_2}+\frac{V_1}{R_3+R_5}}^{\text{outward currents}}=\overbrace{\frac{+10\:\text{V}}{R_1}+\frac{+10\:\text{V}}{R_2}+\frac{0\:\text{V}}{R_3+R_5}}^{\text{inward currents}}$$
So it's not as though there is much of a useful choice.

Redrawing Schematic Addendum
Rules to live by are:

Arrange the schematic so that conventional current appears to flow from the top towards the bottom of the schematic sheet. I like to imagine this as a kind of curtain (if you prefer a more static concept) or waterfall (if you prefer a more dynamic concept) of charges moving from the top edge down to the bottom edge. This is a kind of flow of energy that doesn't do any useful work by itself, but provides the environment for useful work to get done.
Arrange the schematic so that signals of interest flow from the left side of the schematic to the right side. Inputs will then generally be on the left, outputs generally will be on the right.
Do not "bus" power around. In short, if a lead of a component goes to ground or some other voltage rail, do not use a wire to connect it to other component leads that also go to the same rail/ground. Instead, simply show a node name like "Vcc" and stop. Busing power around on a schematic is almost guaranteed to make the schematic less understandable, not more. (There are times when professionals need to communicate something unique about a voltage rail bus to other professionals. So there are exceptions at times to this rule. But when trying to understand a confusing schematic, the situation isn't that one and such an argument "by professionals, to professionals" still fails here. So just don't do it.) This one takes a moment to grasp fully. There is a strong tendency to want to show all of the wires that are involved in soldering up a circuit. Resist that tendency. The idea here is that wires needed to make a circuit can be distracting. And while they may be needed to make the circuit work, they do NOT help you understand the circuit. In fact, they do the exact opposite. So remove such wires and just show connections to the rails and stop.
Try to organize the schematic around cohesion. It is almost always possible to "tease apart" a schematic so that there are
knots of components that are tightly connected, each to another, separated then by only a few wires going to other knots. If you can find these, emphasize them by isolating the knots and focusing on drawing each one in some meaningful way, first. Don't even think about the whole schematic. Just focus on getting each cohesive section "looking right" by itself. Then add in the spare wiring or few components separating these "natural divisions" in the schematic. This will often tend to almost magically find distinct functions that are easier to understand, which then "communicate" with each other via relatively easier to understand connections between them.
You get to choose exactly one node and call it "ground." If the purpose of redrawing the schematic is for understanding it, then choose a node that helps achieve that. When signals are single-ended, they share a common node and you should select this common node as "ground." If the purpose is for analysis, then you can select this for the purpose of reducing the equation complexity. Often, this will mean the node that is "busiest" (has the most terminals attached to it.) Either way, make this choice wisely and it will help a great deal.

The above rules aren't hard and fast. But if you struggle to follow them, you'll find that it does help a lot.
You can read a snippet of my own education by those schematic draftsmen at Tektronix who trained me by reading here.

KCL Addendum
The KCL equations may appear to treat node voltages as if they don't have to be differences, but can be absolute values. However, that's not really the case here. In fact, I'm just using superposition (which is easily seen once you've really had the concepts deepened into you.) This is, in fact, the same technique used within Spice programs (those where I've directly looked over the code used to generate these.)
Perhaps the easiest way to imagine is that absolute voltage at a node spills away from that node through the available paths. But also that absolute voltages spill into that node from surrounding nodes through those same paths. So long as you treat them all as absolute values, the result is the application of a simple superposition concept that results in, effectively, the potential differences controlling the result.
You can test this, easily, by rearranging the resulting equation(s), moving the right side over to the left side and then combining terms. You'll then see the usual potential differences that you expect. So it really is the same result.
The reason I very much prefer this method is that it is simple to visualize and very difficult to make mistakes. You can easily orient yourself to a node and then work out the terms for out-flowing currents for the left side of the equation. Then all you have to do is position yourself at each surrounding node and work out the terms for in-flowing currents for the right side. It's almost impossible to screw that up.
Conversely, when you are instead struggling to work out the potential differences in your mind (using the more traditionally taught method) and just write those terms, you often find yourself not entirely sure if you have the sign right as you try and add them up, correctly. I find, time and time again that not only others wind up messing up somewhere and making an uncaught mistake.. but that I also make those mistakes, as well. Even with lots of experience, you just aren't 100% sure and you often find yourself double and triple checking your work, just in case.
That doesn't ever happen, once you start using the superposition method. It just works. It just works right. It just works right each and every time. I've never, not once, screwed up. (I make typos. But not sign errors.) It's too easy to use.
So voltage spills away from a node via available paths and voltage spills into a node from nearby nodes via the same available paths. The only caveat is that a current source or sink can only flow in, or flow out, but not both directions. It's one way. So it will either appear on the out-flowing side or on the in-flowing side -- but not both sides.
This also works perfectly well with capacitors and inductors. It does turn the equation into a differential/integral equation. But that's just a technicality. It's still correct.

KCL Equation question


No drivers for AMD Radeon HD 8750M or AMD Radeon HD 8550

Question: I have a pretty urgent problem. I bought Asus N56DY laptop, and all of the specs are available here. The only difference is that I replaced the original HDD with an SSD. The graphic cards in question are: ATI Radeon HD 8750M (discrete graphics card) and AMD Radeon HD 8550 IGP (integrated).
My problem is that I can't find any support or drivers for the above items for Ubuntu. I use mostly Ubuntu for work, and because of this, the system acts slower. Has anybody had success in installing this type of graphic card, or has any idea when and if there will be any support for them? Is there any advice that you can give me on how to solve this problem?
Answer: I have KDE(buntu) 13.04 over 3.9 kernel + Catalyst 13.8 beta driver on AMD A10 6800 APU with ATI Richland [Radeon HD 8670D]
As far as I understood from googling (I might be wrong here), Richland GPUs are not yet properly supported in the stable version 13.4. I have installed proprietary beta driver 13.8 on top of 3.9 kernel, and it worked, however OpenGL is glitchy so I use XRender. It works acceptably with occasional effects drop, which is restored by Shift-Alt-F12.
Beta driver is here
http://support.amd.com/us/gpudownload/linux/Pages/radeon_linux.aspx
You may try to set it up this way
http://www.noobslab.com/2013/04/install-ati-amd-catalyst-drivers-in.html
.. or using command line, download and execute.
I would suggest trying kernel 3.8 and stable driver first, however.


Inclusion in the ring of integers

Question: Let $K= \mathbb Q(\sqrt3,\sqrt7)$. I am ask to show that $\mathcal O_K \ne \mathbb Z[\sqrt3,\sqrt7]$, where $\mathcal O_K$ is the ring of integers.
How can i find $\mathcal O_K$ is there a general method on how can i find it? I need help, any hints or links similar to this problem would be appreciated!!   My approach on this problem is to show that $\mathbb Z[\sqrt3,\sqrt7]\subsetneq \mathcal O_K \subseteq \mathbb Q(\sqrt3,\sqrt7)$. However i can't show the following inclusion and from here im stuck. Any help would do thank you!!
Answer: Hint:
You don't have to find $\mathcal O_K$. One can just find an element in $\mathcal O_K$ but not in $\mathbb Z[\sqrt3,\sqrt7]$.
Consider the element $\frac{1+\sqrt{21}}2$. It satisfies the equation $(x-\frac12)^2=\frac{21}4$, i.e. $x^2-x-5=0$.

Hope this helps.
Comment: In general, no, but if at least you know the algebraic degree you can narrow down the possibilities.
Comment: For that other "Q," you probably have to formally ask it as a separate question. Though it is likely that as you type it up, several suggestions come up.
Comment: Thanks a lot this solved the problem!!!
Comment: My other Q about this is there a general method on finding $\mathcal O_K$?
Answer: Yes, there is a general method of finding the ring of integers in biquadratic number fields $K=\Bbb Q(\sqrt{m},\sqrt{n})$ over $\Bbb Q$. Arturo's answer is very helpful in explaining this and giving further links - see
Integers in biquadratic extensions
Of course, in special cases you don't have to determine $\mathcal{O}_K$ explicitly, but it is possible and has been studied well. This site has several posts on it. Here are some examples:
$\mathbb{Q}(\sqrt{m}, \sqrt{n})$ : ring of integers, integral basis and discriminant
On the ring of integers of a compositum of number fields
Ring of integers for $\mathbb{Q}(\sqrt{23},\sqrt{3})$
Algebraic Integers of $\mathbb Q[\sqrt{3},\sqrt{5}]$
Ring of integers of $\mathbb{Q}(\sqrt{-3},\sqrt{5})|\mathbb{Q}$ and group of units
Comment: Thank you very much!
Comment: You are welcome!
Answer: As has already been mentioned, it might suffice to find a "half-integer" in the "composite" intermediate field, in this case $\textbf Q(\sqrt{21})$.
But then I thought, can an example of degree $4$ be found without too much effort? My first try was $$\frac{1}{4} + \frac{\sqrt 3}{4} + \frac{\sqrt 7}{4},$$ but no luck, the minimal polynomial is $256x^4 - 256x^3 - \ldots$ you get the idea.
After various stumblings around that I won't bore you with, I hit upon $$-\frac{\sqrt 3}{2} + \frac{\sqrt 7}{2},$$ which has minimal polynomial $x^4 - 5x^2 + 1$. By the way, I believe this might be the fundamental unit of the ring. Regardless of that, this number is clearly not in $\textbf Z[\sqrt 3 + \sqrt 7]$.
P.S. You might find this helpful: https://www.lmfdb.org/NumberField/4.4.7056.1
Answer: One thing that you can try to find the ring of integers $\mathcal O_K$ is to look at the intermediate fields, and multiply different combinations of "typical" integers in those fields.
With biquadratic fields, you know that there are three intermediate quadratic fields (see Is a biquadratic ring uniquely determined by two intermediate quadratic rings?).
Thus, given squarefree integers $a$ and $b$, we know that $\mathbb Q(\sqrt a + \sqrt b)$ has intermediates $\mathbb Q(\sqrt a)$, $\mathbb Q(\sqrt b)$ and $\mathbb Q(\sqrt c)$, where $c$ is simply $ab$ if $\gcd(a, b) = 1$. Then figure $\theta_a$, $\theta_b$ and $\theta_c$, where $$\theta_n = \frac{1}{2} + \frac{\sqrt n}{2}$$ if $n \equiv 1 \pmod 4$, otherwise $\theta_n = \sqrt n$. Next, compute $\theta_a \theta_b$, $\theta_a \theta_c$ and $\theta_b \theta_c$.
I tried for example $Q(\sqrt{-3} + \sqrt{-7})$. From there, I computed $$\left(\frac{1}{2} + \frac{\sqrt{-3}}{2}\right) \left(\frac{1}{2} + \frac{\sqrt{-7}}{2}\right) = \frac{1}{4} + \frac{\sqrt{-3}}{4} + \frac{\sqrt{-7}}{4} + \frac{\sqrt{21}}{4}.$$ I seem to have made a mistake somewhere along the way: this number's minimal polynomial has a coefficient of $16$ rather than $1$ for $x^4$.
Wait, I see my error: I forgot the simple fact that $i^2 = -1$. Correcting, I find that $$\left(\frac{1}{2} + \frac{\sqrt{-3}}{2}\right) \left(\frac{1}{2} + \frac{\sqrt{-7}}{2}\right) = \frac{1}{4} + \frac{\sqrt{-3}}{4} + \frac{\sqrt{-7}}{4} - \frac{\sqrt{21}}{4},$$ which has minimal polynomial $x^4 - x^3 - x^2 - 2x + 4$.
While this is insufficient to characterize $\mathcal O_{Q(\sqrt{-3} + \sqrt{-7})}$, it is sufficient to demonstrate that 's not Z r-3 r-7 same can do for $\mathcal O_{Q(\sqrt{3} + \sqrt{7

Inclusion in the ring of integers


Conjugate secondary antibody

Question: Why is the secondary antibody conjugated to the enzyme in ELISA, instead of the primary antibody? Wouldn't it be easier to conjugate the enzyme to the primary antibody?
Answer: Making an antibody-enzyme conjugate isn't trivial. By using a primary/secondary set-up you can use the same well-characterised conjugate in combination with many different primary antibodies (as long as these primaries are all raised in the same species). There is also the possibility of some amplification: for example, if the secondary is an anti-Fab then two secondary Igs will bind to each primary.
Response to OP comment
Most primary antibodies in common use are derived from rabbit or mouse, and most are IgG. So, for example, the secondary antibodies goat anti-rabbit IgG and goat anti-mouse IgG will cover most experiments.
Comment: In other words; otherwise you would have to make a conjugate for every primary antibody?
Comment: Yes, that's right.
Comment: @ZafarS: in fact, that is what you do for most immunological techniques, like Western blotting, immunohistochemistry etc.: use an unconjugated primary and a conjugated secondary.
Comment: @AlanBoyd Sorry, I still have some doubt whether I grasp secundary antibodies. Every species has (or better: can have) a secondary antibody per animal right? So for example; we can have secondary antibodies for primary antibodies of rabbits, chimps, mice, etc. So that would still be a lot of possible secondary antibodies, but anyway less than primary antibodies.
Comment: This answer could be improved with an explanation that many times primary antibodies are monoclonal, providing a high degree of specificity to the interrogation of the protein in questions and reducing off-target binding, while the secondary ABs are polyclonal and will bind to multiple sites on the primary AB, thus increasing the signal, say of a fluorescent marker, HRP, or radioactive probe. Though alluded to, cost and time of preparation are important considerations. You can have a stock of goat-antirabbit secondary ABs that will work with every assay you use a rabbit primary AB.
Answer: Another reason that secondary antibodies are used is to look for the production of antibodies by a test animal. Follow me for a second with an example that I think will make it clear.
Our Purpose:
We have identified a protein (call it 'V_Entry') that is vital for Ebola to infect human cells.
We wonder if antibodies against V_Entry will block Ebola infection.
We then use this V_Entry protein as a vaccine in a clinical trial.
Our Question:
Do patients have generate their own anti-V_Entry antibodies as a response to the vaccine. (note: at this point we are not addressing whether these antibodies will be protective or not- that's a separate question)
Our basic protocol:

Day 0: Take blood sample
       Vaccinate patients
Day 14 Take Blood Sample
       Booster Patients
Day 30 Take Blood Sample

To test the ability of the vaccine to generate an antibodies specific to V_Entry, we will assay serum from our cohort via ELISA.
Our Test:
(I'm ignoring controls and other details here to be clear)
Coat ELISA plates with V_Entry protein
Add aliquots of serum from each of out patients at each timepoint.
Wash
Add a secondary antibody conjugated with a detection enzyme
Wash
Add substrate for Enzyme
Allow Enzyme to develop the substrate (usually colorimetric)
Read on a plate reader
Some expected results:

Nothing happens - a control well works, but none of our patients
show antibody generation

Patients have pre-existing antibody that binds V_Entry (maybe these people were already exposed to Ebola?)
Patients have no pre-existing antibody, but they generate antibody in response to the vaccine (control patients not given
vaccine show no new antibody)

Why Secondary Antibody was Necessary:
We can't practically label every antibody made by the patient, but we can use a secondary antibody (perhaps Goat Anti-Human IgG) to detect any human IgG that has stuck to the V-Entry on our plate.
Was this a long run for a short slide?
I considered making a slide for each step of the protocol, but I started wondering if I'm avoiding something...

Conjugate secondary antibody


AWS EBS recover data from EBS

Question: I have this t2.micro on my aws account, after a update/reboot i can't log in to my machine thought ssh...
I have tried by aws panel, stop and start machine but nothing works...
So i created another machine with a new volume, everything is working fine..
Is it possible to attach my old volume to my new machine to copy some files? if yes there is some different config? because everytime i do i can't login
Answer: I did it, the trick is attatch the second volume on a running instance then follow this tutorial to mount (Skip the format part)
https://devopscube.com/mount-ebs-volume-ec2-instance/

AWS EBS recover data from EBS


Quality issues with mov to mp4 video conversion through handbrake

Question: I am converting mov video files to mp4 through handbrake tool but the video quality is getting disturbed in the windows media player. It is working fine with the vlc player. How do I resolve this issue. I need to convert these videos to a very low video size
Answer: This is probably a computer hardware problem. I have had this problem as well, but there was no way of stopping it. Try viewing the videos/audios on a different, more powerful computer.
Hope this helps.


Robert Fischer took the plane with Cobb's team?

Question: Why did Robert Fischer take the plane with Cobb's team in Inception (2010), and how did he get sedated on the plane?
Comment: Isn't this explicitly explained in the film? (Saito bought the airline, and the drug's in the drink.)
Comment: i think the easiest way to explain this is that Cobb's team took the plane with Robert Fischer.  Not the other way around.  Saito bought the airline to ensure he would be able to get the team on whatever flight he booked.
Answer: This is actually explained in the film. First they find out that he routinely takes the flight Sidney - Los Angeles. Then they cause trouble with his private jet so he has to fly with public transport. And Saito just buys the whole airline for them to have all the freedom to organize being his co-passengers and have flight attendants they can trust:

Saito: Sidney to Los Angeles, one of the longest flights in the world. He makes it every two weeks.
Cobb: He must be flying privately.
Saito: Not if there were unexpected maintenance with his plane.
Arthur: Would have to be a 747...In a 747 the pilot's up top and the first class cabin's in the nose so noone would walk through. But you'd have to buy out the entire cabin and the first class flight attendant.
Saito: I bought the airline...It seemed neater.
Cobb: Looks like we have our 10 hours.

And how Fischer got sedated is explained, too, though a bit more visually. First Eames steals his passport in order for Cobb to get him into a conversation later. Then Cobb hands him his drink and secretly slips some drug into it. Now if this is the final sedation or just something to knock him out until they get him to the dream machine (that comes with its own sedative) is not clear, but it certainly was to get him sleep away for the next steps of the heist.
Comment: I've taken the liberty of adding in a quote from the screenplay that refers to the scene.
Comment: @Valorum Your good intentions are honestly appreciated. However, I generally prefer not to employ the screenplay when it isn't necessary, as the film is the primary source. I explained how the scene pans out in the film itself and added images showing exactly that. The screenplay really doesn't say anything else than that. And the added dialogue about Fisher's father is relevant to the other linked question (and is already there), but not necessary here.


Can't run PhantomJS with mocha on node js

Question: I'm trying to run phantomjs with these params:
mocha-phantomjs -s disk-cache=no --ignore-leaks -R xunit tests/index.html

but allways got this respond:
events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: spawn ENOENT
    at errnoException (child_process.js:980:11)
    at Process.ChildProcess._handle.onexit (child_process.js:771:34)

I use ubuntu 13, mocha-phantomjs 3.1.0 and node v0.10.15.
Any googling doesn't helps and I just can't figure out what to do.
All what i did before, is just install node and mocha-phantomjs
Can anyone help me?
Comment: This can happen on Windows as well.
Answer: I have seen this error on a windows machine, and solved it by copying phantomjs executable to the node.js folder.
Make sure that either
phantomjs executable is in PATH
or
phantomjs executable is in node.js folder.
Answer: Another option on Windows, that's slightly cleaner:
Download Phantomjs. Decompress the zip someplace (c:\dev\phantom or whatever) and add it to your path.
Install mocha-phantomjs globally using npm:
npm install -g mocha-phantomjs

And you should be all set.


Apache redirect by without URL rewriting

Question: Is there a way I could achieve redirecting to another site, without losing the original URL?
So, what we'd want to achieve is to be able to access:
somesite.com/some/url -> someothersite.com/some/url
but we'd like to retain somesite.com/*.

In other words, we'd want to access every URL of someothersite.com via somesite.com.
Answer: If you're trying to redirect just a subdirectory of the server, you can use mod_rewrite like this:
RewriteCond %{REQUEST_URI} /some/url [NC]
RewriteRule ^(.*)$ other.example.com/$1 [R]

If your trying to show the content of the other site without the user seeing the other url, you'll need both mod_rewrite and mod_proxy
RewriteCond %{REQUEST_URI} /some/url [NC]
RewriteRule ^(.*)$ http://other.example.com/$1 [P]

Other configuration steps may be necessary for mod_proxy, depending on your environment.
Apache's Advanced mod_rewrite Guide may be of benefit.
Answer: Are you actually looking for a redirect, or to have that other site's content appear under your original URL (more proxying)? I'll assume that the other server is your content and either internal/backend or if public you're aware of the negative SEO implications. If someothersite.com is not your site and content, you probably shouldn't be doing this.
You'll need to have mod_proxy and mod_rewrite running, which is likely uncommenting the lines mentioning it if not already done.
Then in the somesite.com config:
RewriteEngine on
RewriteRule /some/url(.*) http://someothersite.com/some/url$1 [P,L]
Answer: I'd just throw in a file that simply redirects the user with an HTML meta-refresh, or if you want to redirect the user in the most accepted way possible, throw in a 301 redirect rule in an .htaccess file somewhere on the site.
Example:
Redirect 301 /some/url http://newsite.com/some/url

Comment: A meta-refresh would affect the www.example.com page as well; and you'd have to add it to every single page in the whole site for it to work correctly. Adding a redirect in an .htaccess file wouldn't work if there's no default record for example.com.
Comment: Hm, good point.  I've probably read the question wrong: I see that he wants to redirect EVERY URL from somesite.com to someothersite.com; however, this could use some clarification.
Comment: Added clarification as per your inputs. :)


.NET SqlConnection NIC usage

Question: Having a computer with multiple NICs, I need to specify somehow the one to use for the connection to SQL Server.
Answer: Following on from @pzycoman, SqlConnection (and SQL OLEDB/SQL Server ODBC) has no explicit connection string semantic to express the bound NIC other than to specify the destination server host address (which in turn triggers the  route metrics discussion).  Splitting out  services or applications onto different subnets can work - but equally can also generate the utilization asymmetry similar what you see today.
Another potential option would be NIC teaming if your adapters support it.  Teaming software bonds multiple NICs into a single logical channel for increased throughput with less NetOps complexity.  This happens at a much lower level in the OSI and as such is transparent to your applications and services.
Teaming used to be frowned on for a number of reasons (predominantly NLB issues and driver quality), but those have been largely mitigated in the last couple of years.
As always engineering mentality will help - test everything.
Answer: If the NIC's have diffrent subnets, windows should automatically route the request through the right NIC (running "route print" from the command line will show you what gets routed where)
Answer: The windows networking stack will figure out which nic to use to reach your database server. If you use the netbios name of your sql server in the connection string you might want to replace it with the IP adress (or dns entry) in the subnet that your preferred nic is on.

.NET SqlConnection NIC usage


Can ISPs see my connection with a hidden service if I use Tor2Web or a similar proxy?

Question: If I use Tor2Web on a normal web browser such as Google Chrome, can ISPs monitor or intercept my connection with a hidden service?
Comment: Yes probably, tor use specific relays with specific ip. But I think they can't view what you're doing...
If I were you, I'll not use Tor2Web
Answer: They can see that you are connecting to that proxy. They cannot see what you are doing there, because it is HTTPS. However, it is far less secure than using TOR, because, if they seize that proxy server, they can see everything you are doing on the dark web.
Comment: Thanks so much for clearing this up!


How is antibody production stopped?

Question: Once clonal selection is done, B cells would start dividing and producing antibodies. So, after an antigen is eliminated, what stops the division of B cells and antibody production?
Answer: Upon activation plasma B cells upregulate death receptors as part of being activated. Presence of the antigen overcomes the death signal, thus the cell survives. When antigen is lost, the death signals overcome the survival signals as there is no antigen, so the B cell dies via apoptosis.
Memory B cells don't do this. They survive and continue to produce antibodies for years, although this slowly wanes. Antibodies have to be produced as antibody mediated immune mechanisms are extremely important for memory and the reason why a subsequent infection is cleared so rapidly. Furthermore for the example of HPV, antibodies induced by the vaccine prevent the virus even infecting cells (so called neutralising antibodies).
Answer: You are right to say that Plasma Cells are terminally differentiated, so they don't become the memory cells, or calm back down or anything. But all Plasma Cells are not the same, there are Short-Lived Plasma Cells (SLPCs) that are less specific, but arise rapidly after stimulation, and there are Long-Lived Plasma Cells (LLPCs) that come about later and have more specific antigen binding.
SLPCs are rapidly activated, but also rapidly lost. These are the cells that Android was talking about when s/he said that apoptotic programs are initiated as soon as cells become activated and are eventually eliminated by these mechanisms.
LLPCs are the cells that stay in your body for a much longer time (theoretically for life, but probably not practically unless you get hit by a bus in a couple of years). When you get a vaccination, these are the cells that produce antibody that can be detected in the blood for a number of years (what testing your antibody titer looks for). These cells are in pretty limited supply, so we know less about them. My guess is that they are not actively eliminated, but may become eliminated over time by other mechanisms (purposely undefined here).
Answer: My understanding of this question is: Antibodies are produced by plasma cells which are terminally-differentiated B cells. Maturation of B cells to plasma cells is stimulated by the presence of antigen (T cells, cytokines, etc. etc).
In the absence of antigen the existing plasma cells undergo apoptosis, and the maturation of the cognate B cells will not be stimulated, so no more plasma cells will be produced.
I have found it surprisingly difficult to find references in support of these statements, although there is a large literature on the suppression of apoptosis in memory B cells.
Comment: Alan, you might try Ralph Zinkernagel's review: http://www.ncbi.nlm.nih.gov/pubmed/24909054. I don't have full access to the article, but it appears that he summarizes work showing the half-life of various types of Plasma Cells. I'm not sure to what extent anyone has looked into the apoptosis pathway that may be involved in these cells particularly.  Klaus Rajewsky has done work assessing the half-life of naive B Cells. It's possible that he has a review somewhere that can point you in the right direction. Good luck - and please post anything useful you find here.

How is antibody production stopped?


can't delete or use unallocated partition

Question: I have a couple of very small unallocated partitions that I cannot delete or merge with adjacent partitions.  I have tried Gparted on live Gparted cd and from the gparted app on Ubuntu live cd as well as from Windows Drive Management. The delete option is greyed out.  The partitions are very small but just shouldn't be there. I think they are remnants from old linux installations.  Any help on cleaning this up would be appreciated.
Comment: We probably all have them (I have a 1.02Mb one) Can you add a picture of the partition  setup from gparted?
Answer: Those little gaps of unused space on your HDD could be because you used a Windows partition program at some point; Windows partition editors often use different HDD geometries than the standard that Linux uses, and because partitions typically end and start at cylinder boundaries, you can end up with little gaps of unused space if you use a Windows partition editor and Linux partition editor on the same drive.
I would suggest leaving them as is. If you have Windows on your sda1 NTFS partition, and if you try to move the beginning of that partition to claim the 1 MB of unallocated space at the beginning of the drive, doing that will make Windows unbootable. Source.

If you do want to get rid of these you probably need to umount the partition next to it and use the "round to cylinder" option in gparted:
Answer: If it is Unallocated it would mean it is blank space with no partition in it at, which means you just need to expand a current partition to use up that space if you want it.


What is the origin of the word digicam? When and where did it originate?

Question: Supposedly the word digicam (digital camera) originated in 1989 as a trade name in England, but I have not found any further information.
Comment: Personally, I've not seen *digicam* used frequently. Maybe more so back when film cameras were ubiquitous and digital cameras a novelty? (Today, the opposite is mostly true.)
Comment: It was the name used when   the first  digital camera became available on the market in those years. Just ***digi*** ( digital) ***cam*** ( camera) to distinguish them from non digital products.
Comment: Built by Ampex in our new California facilities, the Digicam was designed to produce the highest quality picture both on location and in the studio. A Computer In a Portable Head. The BCC-20 Digicam's computer-in-thehead technology ...(1980) https://www.google.it/search?q=%22digicam%22&tbs=bks:1,cdr:1,cd_min:1980,cd_max:2000&lr=lang_en&gws_rd=cr,ssl&ei=c6eOVfqYI4WssAGNhIboDA
Answer: The Free Dictionary offers the following definition of digicam:

digicam n. Informal A digital camera.

However, the first occurrences of the word digicam in a Google Books search results use the term to refer to a TV videocamera for shooting videotape.
Here is the Ngram chart for digicam for the period 1970–2005:

The three earliest instances of digicam (short for "digital videocamera") that a Google Books search finds are from 1980—and all three refer to videocameras manufactured by Ampex (of Redwood City, California) that debuted in 1979. From Filmmakers, volume 14 (1980) [combined snippets]:

Internal circuitry compares the camera's current operating conditions with a previously established set of operating parameters, and automatically adjusts the camera to optimum settings. Ikegami and Hitachi offer computer set-up as options on their top-of-the-line studio cameras. Ampex offers the BCC-14 Digicam, which is a computer controlled ENG/EFP camera. While a computer set-up camera is expensive to purchase initially, time and manpower savings make such a system attractive to high volume production facilities.

From an Ampex advertisement in Broadcasting Cable Yearbook (1980) [combined snippets]:

THE BCC-20 DIGICAM.
Our new EFP camera features computer-in-the-head technology that combines a microprocessor and digital memory with a powerful software program for full-time video control of the camera.
Digicam can achieve 0.06% registration in all zones of the TV picture quickly in addition to giving the operator automatic or manual set-up with results that surpass those of a conventional camera.

And in an Ampex advertisement from International Broadcast Engineer, volumes 170–190 (1980[?]) [combined snippets], cited by Josh61 in a comment above:

Built by Ampex in our new California facilities, the Digicam was designed to produce the highest quality picture both on location and in the studio A Computer In a Portable Head. The BCC-20 Digicam's computer-in-the-head technology combines a microprocessor and digital memory with a powerful software program to give you full-time digital control of the camera.
Even with the power turned off the Digicam's memory-on-the-head stores the operating parameters.

The TV Camera Museum confirms that the Ampex BCC-14 ("Portable Colour," according to the site) was released circa 1980, and the Ampex BCC-20 ("Portable ENG Colour") in 1980. Various Ampex Digicams are mentioned in publications throughout the early 1980s.
Though the drop-off in frequency of use of the term digicam since 2003 (indicated in the Ngram graph above) may be exaggerated by incomplete data, I suspect that, as cell phones have become more and more capable of handling video and photography, the consumer market for digital cameras and videocameras (sometimes called camcorders) has waned. For its part, Ampex went out of business in October 2014, according to the Wikipedia article about it.
Comment: The Ampex product you describe sounds like a digitally-controlled camera, not a digital-image camera. It would be interesting to know when, if ever, D(d)igicam came to refer to digital-image cameras, whether still or motion.


Carbide machining inserts are supposedly extremely brittle but they don't break when machining why?

Question: So everywhere I read I hear that carbide inserts for metal machining are extremely brittle and they will break very easily if you say drop them. However, you put them in your tool holder and spin up your lathe or mill and you can easily use them to cut hard materials. Why does the insert not have a problem cutting the material but would shatter if you dropped it? If you use one on a lathe and all of a sudden a piece of metal spinning at quite the speed smacks into the end of it is that force not going to impart similar forces on the material?
Answer: Tungsten carbide tooling is not typically so weak that it will outright break merely from dropping.
However, WC tools are brittle, by which it is meant that when a stress is applied above some limit, instead of undergoing plastic deformation they will shatter. So the term brittle refers to the way the material responds to stress, and it does not mean the material cannot withstand any degree of stress. Ductile materials respond to high stress through plastic deformation (and eventually failure).
Another thing to bear in mind is that during machining operations, cutting forces are applied gradually, are typically in the range of hundreds of newtons, and are usually not concentrated at a particular spot. Whereas if a tool unintentionally moves into material rapidly without being able to cut, the forces can exceed tens of thousands of newtons, and tools will easily shatter. Also, when dropped, impact stresses can exceed the strain limit of the material, if for example a heavy tool with a thin cutting edge lands directly on the thin edge. In that case the edge might chip.
I have dropped WC tools many times and they have never broken. In fact, just now, to test this, I dropped a large heavy 16 mm end mill (I have access to a lot of machine tools) from head level on to a steel plate several times and there was no fracture. Tools with certain shapes may chip however.
Comment: I'm a little confused as to how moving into a material rapidly has a force that are any different than if you take it slow. If a point 1mm from the outside of a cylinder has some amount of torque if you come up slowly on it or come up quickly on it it's going to exert the same amount of force on the carbide insert no? So if its enough to shatter it in one case why isn't it enough to shatter in the other?
Comment: I mean in the case where it's not cutting, e.g. if the spindle is turned off.
Comment: Additionally though, cutting faster requires more force (and more spindle power) than cutting more slowly. The reason is because when you cut faster, you are creating thicker and/or more chips, which require more force to remove.


"She's got you high and you don't even know yet"- What does this sentence mean? Help needed!

Question: I was watching a film named "500 days of Summer" and at the end there was a song starting like "She's got you high & you don't even know yet". Since I'm not a native speaker, I don't understand what does it mean? I need some help.
Comment: In case it helps anybody for context, the song is "She's got you high" by Mumm-Ra. The lyric is used repeatedly as the hook.
Answer: She has put you in a euphoric or inebriated mental state, a state where your judgment may be impaired, and so far you are unaware that this has happened.
I don't know that song, so it's impossible for me to say whether the singer or lyricist thinks this fact is good news or bad news, happy or sad, funny or tragic, a lighthearted jibe or a serious warning.
Answer: "High" can be used to a refer to a mental state, usually a euphoric one. This can be used to refer to an induced state of euphoria from drugs, but it is also used to describe other natural states of happiness (eg "I'm on a high").

"She's got you high and you don't even know yet"

It is impossible for anyone but the songwriter to say authoritatively what the song lyrics mean, but it seems to me that the song is about someone in relationship with a girl who is making them very happy. The girl may love the person, or they may even be in love but either the person doesn't realise it or is in denial.
"She's got you high" means that the unnamed girl has made the person euphorically happy, maybe that they are even in love; and "You don't even know yet" implies that the person has not yet realised they may be in love, or perhaps just what a good thing this relationship is.
Other lyrics from the song that support this interpretation:

You can't deny you're looking for the sunset

Perhaps this means metaphorically that the person is looking for something beautiful? Again there is a suggestion of being in denial.

It's the search for the time before it leaves without you

Suggesting that if the person doesn't realise this girl is a good thing and respond, she will move on.

What's this about? I figured love would shine through

The writer is saying that love should be obvious, but the person hasn't realised it.

Open your mind, believe it's going to come to

Telling the person in the song that they may be in denial that love will ever come their way, but that this is "closed minded" thinking.
Comment: @JimReynolds I didn't say it was *first* used that way, I said "historically". Also "in high spirits" is different to saying "I'm high" or "on a high".
Answer: The question is what is it that "You don't even know yet?"  It's that Summer does not love you, will never love you.  As a character in a movie once said, "I didn't know that only one person could fall in love - I thought it was always two people."  (I can't remember the movie, just that line.)  And at the end, when he tries to start up a relationship with "Autumn," he drops out of character to seemingly ask, "Am I going through this again?"
Comment: Thank you for your answer. The name of that film is "500 days of summer"


Debian NFS auto-unmount if the host PC is turned off

Question: I have a home network with two Debian Stretch PCs. In each one, I have a directory called share, shared via NFS, where I put stuff I want to copy from the other PC through NFS. After auto-mounting on boot, there's a problem if the other PC goes off: any window (Nautilus, Firefox "open" or "save as", Terminal "ls"...) that shows the ~/home directory (where share is) freezes, waiting for the mounted share. Is there a way to auto-unmount, if any window finds out that the share is not accessible anymore? How do home networks usually address this issue?
Answer: You should use soft mount option for your nfs mount, which should solve your issue with applications hanging when trying to access unavailable nfs server.
hard/soft mount options control nfs recovery behavior. man nfs explains:

Determines the recovery behavior of the NFS client
                        after an NFS request times out.  If neither option is
                        specified (or if the hard option is specified), NFS
                        requests are retried indefinitely.  If the soft option
                        is specified, then the NFS client fails an NFS request
                        after retrans retransmissions have been sent, causing
                        the NFS client to return an error to the calling
                        application.

Additionally, AutoFS is commonly used to implement on demand automatic mounting/unmounting.
Comment: "NB: A so-called "soft" timeout can cause silent data corruption in certain cases. As such, use the soft option only when client responsiveness is more important than data integrity. Using NFS over TCP or increasing the value of the retrans option **may mitigate some of the risks** of using the soft option." This doesn't seem good enough to me. AutoFS seems to be my only hope here.
Comment: You don't need AutoFS here, systemd automounts provide pretty much the same functionality (see your previous question).


Exponential family and conjugate priors

Question: Is a distribution that belongs to the exponential family necessarily conjugate prior?
Comment: Related: https://stats.stackexchange.com/questions/192554/aside-from-the-exponential-family-where-else-can-conjugate-priors-come-from
Answer: "If the likelihood function belongs to the exponential family, then a conjugate prior exists", not the other way around. For example, many popular discrete distributions come from exponential family and have conjugate priors, but are not conjugate priors for other distributions, because the parameters of most distributions are not discrete.
Comment: It is unclear to me why restricting the support of the parameter in the prior (or the dominating measure) is a reason for dismissing this prior. It is an unusual setting but not a contradiction of the definition of conjugate families.
Comment: @Xi'an I meant it rather as an example than a contradiction.
Answer: A bit of reverse engineering: for the likelihood function associated with an exponential family, with natural parameterisation $\theta$ and sufficient statistic $x$
$$\ell(\theta|x)\propto \exp\{\theta^\prime x-\tau(\theta)\}\quad x\in\mathcal X,\ \theta\in\Theta$$
a family of conjugate priors is made of distributions with densities
$$\pi(\theta|x_0,\lambda)\propto \exp\{\theta^\prime x_0-\lambda\tau(\theta)\}\quad x_0\in\mathcal X_0,\ \lambda\in\Lambda$$
with respect to an arbitrary dominating measure $\text d\nu$ on $\Theta$, provided

$\mathcal X_0+\mathcal X\subset\mathcal X_0$
$\Lambda+\mathbb N \subset \Lambda$
$\int_\Theta \exp\{\theta^\prime x_0-\lambda\tau(\theta)\}\,\text d\nu(\theta) <\infty$ for all $x_0\in\mathcal X_0,\ \lambda\in\Lambda$.

It clearly defines an exponential family with sufficient statistic $(\theta,\tau(\theta))$.
The reverse problem is to start from an exponential family density on $\theta$
$$\pi(\theta|\xi)\propto\exp\{T(\theta)^\prime\xi-\delta(\xi)\}\propto\exp\{T(\theta)^\prime\xi\}$$
and to identify a likelihood enjoying the above as a conjugate family. This means first breaking $T(\theta)^\prime\xi$ into $\theta^\prime x_0-\lambda\tau(\theta)$ and second finding  a measure $\text dμ$ on $\mathcal X$ such that
$$\int_{\mathcal X} \exp\{θ′x\}\text dμ(x)=\exp\{τ(θ)\}$$
This is an issue when considering for instance the Poisson distributions
$$\pi(\theta|\xi)\propto\exp\{\theta\xi-\log(\theta!)\}\mathbb I_\mathbb N(\theta)$$
because $\theta$ and $\xi$ are unidimensional. One would thus need to embed the Poisson family into a two-dimensional family
$$\pi(\theta|\xi,\lambda)\propto \exp\{\theta\xi-\lambda\log(\theta!)\}\mathbb I_\mathbb N(\theta)$$
and then check if there exist $\lambda_0\in\mathbb R$,  a set $\mathcal X\subset\mathbb R$, and a measure $\text d\mu$ on $\mathcal X$such that
$$\int_\mathcal X \exp\{\theta x\} \,\text d\mu(x)=\exp\{\lambda\log(\theta!)\}\quad \forall\theta\in\mathbb N$$

Exponential family and conjugate priors


Function of brownian motion is a martingale

Question: Let $B_t,t\geq 0$ a brownian motion and $u(t,x)$ a function satisfying the following PDE $$\frac{\partial u}{\partial t}+\frac{1}{2}\frac{\partial^2 u}{\partial x^2}=0.$$ Then we prove that $\frac{\partial }{\partial t}\Bbb{E}(u(t,B_t))=0$, but I want to prove that $u(t,B_t)$ is a martingale (without using Itô formula).
I think it suffices to show that $u(t,B_t)$ is a submartingale or supermartingale.
Thanks.
Comment: Actually, you would have to use at some point that $u$ solves the PDE. With applying Ito formula, the only way you can use it, as I see, is to write the explicit expression of $u$ via the fundamental solution (=Gaussian density) and deal with integrals w.r.t. conditional distributions of Brownian motion. Perhaps, doable - but Ito's formula seems to be much easier.
Answer: You can apply the following theorem to prove $u(t,B_t)$ a martingale. The main idea is -as Ilya wrote- to use the fact that the density $p(t,x)$ of a Gaussian distribution with mean 0, variance $t$ solves $$\frac{\partial}{\partial t} p(t,x) = \frac{1}{2} \frac{\partial^2}{\partial x^2} p(t,x) \qquad (x \in \mathbb{R},t>0) \tag{1}$$.

Theorem Let $(B_t)_{t \geq 0}$ a Brownian motion and $u \in C^{1,2} \cap C([0,\infty) \times \mathbb{R})$ such that $u$ and its partial derivatives are exponentially bounded. Then $$M_t^u := u(t,B_t) - u(0,B_0) - \int_0^t \underbrace{\left( \frac{\partial }{\partial t} + \frac{1}{2} \frac{\partial^2}{\partial x^2} \right) u(r,B_r)}_{=:Lu(r,B_r)} \, dr$$ is a martingale.

Sketch of the proof: By the Markov property of the Brownian motion, one can show that
$$\begin{align*} \mathbb{E}(M_t^u-M_s^u \mid \mathcal{F}_s) &= \mathbb{E} \left( u(t,B_t)-u(s,B_s) - \int_s^t Lu(r,B_r) \, dr \mid \mathcal{F}_s \right) \\
&= \mathbb{E} \left( u(t,B_{t-s}+z)-u(s,B_0+z) - \int_0^{t-s} Lu(r+s,B_r+z) \, dr \right) \bigg|_{z=B_s} \\
&= \mathbb{E} \bigg( \underbrace{\varphi(t-s,B_{t-s}) - \varphi(0,B_s) - \int_0^{t-s} L\varphi(r,B_{r}) \, dr}_{M_{t-s}^{\varphi}-M_0^{\varphi}} \bigg) \bigg|_{z=B_s}  \end{align*}$$
where $\varphi(t,x) := u(t+s,x+z)$. To prove that this expression equals $0$, use Fubini's Theorem, partial integration and $(1)$ to show that
$$\mathbb{E}(M_t^{\varphi}-M_{\varepsilon}^{\varphi}) = \int (p(t,x) \cdot \varphi(t,x)-p(\varepsilon,x) \cdot \varphi(\varepsilon,x)) \, dx \\ - \int_{\varepsilon}^t p(r,x) \cdot \left( \frac{\partial}{\partial t} + \frac{1}{2} \frac{\partial^2}{\partial x^2}  \right) \varphi(r,x) \, dx \, dr = 0$$
for $t > \varepsilon>u$. Finally, by Doob's maximal inequality and the exponential boundedness, one can apply dominated converence to conclude that $$\mathbb{E}(M_t^{\varphi}-M_0^{\varphi}) = \lim_{\varepsilon \to 0} \mathbb{E}(M_t^{\varphi}-M_{\varepsilon}^{\varphi}) = 0$$
This finishs the proof.
(For more details, see e.g. René L. Schilling/Lothar Partzsch: Brownian Motion - An Introduction to Stochastic Processes, Theorem 5.6.)

Actually, the mentioned theorem is a special case of the following theorem:

Theorem Let $(X_t)_{t \geq 0}$ a Feller process with generator $A$. Then $$f(X_t)-f(X_0) - \int_0^t Af(X_r) \, dr$$ is a martingale for any $f$ in the domain of $A$.

So, in your case the process is given by $X_t := (t,B_t)$. With some knowledge about generators, it's not that difficult to show that the generator $A$ is given by $$A = \frac{\partial}{\partial t} + \frac{1}{2} \frac{\partial^2}{\partial x^2}.$$ (This leads to the topic of transition semigroup and its generator. It's also contained in the book, chapter 7.)
Comment: Thank you for your answer. I have a question maybe stupid why we don't compute directly $\Bbb{E}(u(t,B_t)-u(s,B_s)|\mathcal{F_s})$ and use the same arguments used in your proof. My objectif is to prove that $u(t,B_t)$ is a martingale not $M_t^u$.
Comment: @bmo Yes, of course. In your example, we have $Lu = 0$, i.e. $M_t^u = u(t,B_t)-u(0,B_0)$. So you can either apply the theorem or adapt the proof.
Comment: very nice proof that deserves to be more seen (y)


Generate PHP Interfaces

Question: Is there a tool the generate php interface from existing classes?  It would be nice to have a tool like Netbeans automatic getter/setter creation but for interfaces.
Comment: What you are talking about? Getters/Setters for interfaces don't make any sense, because interfaces cannot have properties. You should clarify your question
Comment: @KingCrunch `nice to have a tool like Netbeans automatic getter/setter creation`  Netbeans offers a "autogenerate getters and setters from the classes properties feature.  He wants something like that for interfaces. "Generate interface from class"
Comment: Ah, I see. Probably edorian already gives an answer, but usually (according "design-by-contract") you should always have the interfaces first and create the classes according their signatures. (Just wanted to mention this)
Answer: For programmatic usage there is InterfaceDistiller that allows you to derive interfaces from existing classes like this:
$distiller = new InterfaceDistiller;
$distiller
    ->methodsWithModifiers(\ReflectionMethod::IS_PUBLIC)
    ->extendInterfaceFrom('Iterator, SeekableIterator')
    ->excludeImplementedMethods()
    ->excludeInheritedMethods()
    ->excludeMagicMethods()
    ->excludeOldStyleConstructors()
    ->filterMethodsByPattern('(^get)')
    ->saveAs(new SplFileObject('MyInterface.php'))
    ->distill('SomeFoo', 'MyInterface');

It also has a CLI interface:
Usage: phpdistill [options] <classname> <interfacename>

  --bootstrap                           Path to File containing your bootstrap and autoloader

  --methodsWithModifiers <number>       A ReflectionMethod Visibility BitMask. Defaults to Public.
  --extendInterfaceFrom  <name,...>     Comma-separated list of Interfaces to extend.
  --excludeImplementedMethods           Will exclude all implemented methods.
  --excludeInheritedMethods             Will exclude all inherited methods.
  --excludeMagicMethods                 Will exclude all magic methods.
  --excludeOldStyleConstructors         Will exclude Legacy Constructors.
  --filterMethodsByPattern <pattern>    Only include methods matching PCRE pattern.
  --saveAs                              Filename to save new Interface to. STDOUT if omitted.

I'm not aware of any IDE that offers such functionality for php.
Answer: Currently PHPStorm 8 can do this, maybe prior versions as well.
Steps:

Place your cursor on the class name
Choose: Refactor -> Extract -> Interface
Fill out the options and done.

Generate PHP Interfaces


Doppler shift in signals

Question: I have started doing some reading into the effects of the doppler shift on signals. In particular, radar signals from ships moving relative to a receiver. This might seem weird but I understand why the shift in frequency happens what I don't understand is how that changes the actual signal. If we receive the signal and perform an FFT on it do we get the original frequency plus another component that corresponds to the doppler effect? Is the doppler shift similar to some sort of distortion on the signal? To be honest it is hard for me to ask the right question. I think I am missing an intuitive picture of what happens to the signal as a result of a doppler shift. If anyone would help i would really appreciate it.
Answer: It is well-known that Doppler effect shifts the received frequencies compared with the emitting frequencies. On the other hand, the time period of the sound signal is often ignored.
Say a sound source is approaching you. For the sound source itself, it emits a sound signal for $T$ seconds, but you will hear a sound less than $T$ seconds, causing an increase in the frequency. Let's take an extreme example, if the sound source is running towards you at the speed of sound, all the wavefronts and the sound source itself reach you at the same moment, and you will hear a huge amount of sound energy, which is called sonic boom.
It's not a distortion, only a stretch on the time scale. For discrete signal, all you have to do is to change the playback speed, or to interpret the sampling rate and do a resample.
Due to the connection between the time scaling and the frequency shifting, audio time stretching and pitch scaling have become research interests, which mean changing the speed without affecting the pitch, and the opposite, changing the pitch without affecting the speed.
Answer: So, let's take this from the top down:

Thanks to Fourier, we know we can describe all signals as combination of harmonic oscillations.
For a harmonic oscillation sent at frequency $f_t$, you know the received frequency is $f_r=\left(1+\frac{\Delta v}c\right)f_t$.
So $\left(1+\frac{\Delta v}c\right)=:d$ is a constant (for any fixed speed) that you multiply with all frequencies, and you get the new frequencies

So, that technically answers your question: you "stretch" all frequencies out by a factor $>1$ if approaching, $<1$ if leaving.
The trick is that usually, radars use high carrier frequencies, and bandwidths that are significantly smaller. So, for all frequencies "close to" $f_t$, it looks like they're subject to the same frequency "shift" (altough it's not actually a shifting, it's a scaling; just an approximation!).
So, what you often find is that people say "we use the narrowband approximation", and then, simply, say all frequencies get shifted by the same amount – the carrier frequency times our Doppler shift constant. That's actually why it's called Doppler shift: it shifts spectra (locally. Globally, it scales them.).
Answer: Observing a ship via radar waves is exactly analogous to observing a fire truck via sound waves. If a moving sound source (it doesn't matter if the source or the observer is moving, the relative velocity is what counts) passes your ear; do you hear more tones than when it's at rest? No.
The Doppler shift changes the frequency of the signal, it does not add frequencies.

Doppler shift in signals


Is code interpreted at every call in Web2Py?

Question: If so, What is the advantage ? (sure it will avoid restarting webserver). But isn't it a perfomance bottleneck? For production, is it possible to make web2py run directly from bytecode skipping interpreting stage (Caching) (except for the first request) ?
Answer: In web2py, by default, all code in models, views and controllers (not web2py code, not code in modules imported by your models, views, controllers) is interpreted at every request. This allows to use a third party web server (for example apache) and still be able to see changes in your code reflected immediately without restart. PHP works in the same way. The performance penalty is negligible because the time to parse your code is less than the time to execute your code.
Anyway, in the admin interface there is a "compile" button that will bytecode compile your code and collapse the view hierarchy (extended and included views) into a single file per action and remove the performance penalty. It also allows you to distribute your code bytecode compiled without giving away the source. The license allows it.
Answer: I don't know web2py particularly, but it runs via WSGI like most other Python frameworks. This means that code is only interpreted when the process starts, and is otherwise kept in memory. Processes are dynamically started and killed by the web server itself, but usually last for multiple requests.
In any case, the Python interpreter usually creates a byte-code file, <code>.pyc</code>, when code is first read. This works in a webserver environment just as it does anywhere else.
Finally, however, it is generally considered that code parsing is not particularly a bottleneck - the conversion to bytecode is pretty quick. In a web application, your bottleneck is almost certainly elsewhere (probably in the connection to the database).


Install Google Chrome Nag

Question: Good Morning All.
I am using Ubuntu 15.04 and Firefox 44.0. Software Centre keeps nagging to install Google Chrome, which I don't want.
Is there a way to turn off the nag?
Any assistance appreciated, thanks.
Comment: I have never seen something like this before. It also cannot be possible since Google Chrome is not in Software Centre  at all. Can you send a screenshot when you get it?
Comment: Could you please attach a screenshot to show how exactly its "nagging" ?
Comment: Do you mean "lag" ?? like hanging/freezing ?? and you want to avoid that ?? and also, are you referring "Chromium" ? because google chrome is not there in Default repos,..
Comment: Thanks for the help. Screenshot - /home/ted/Pictures/Screenshot from 2016-03-12 17:00:46.png
Comment: Screenshot left on your PC won't help anybody. Upload it to http://imgur.com and provide a link here.
Answer: Since your Software Centre keeps nagging , install Google chrome via Terminal.
To install GOOGLE CHROME , first we need to add the Google Chrome PPA.
1.Import the Google Chrome PPA key from the command below.
wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

2.Next set up the repository , by executing the below command.
sudo sh -c 'echo "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list'

3.Update the repositories.
sudo apt-get update

4.Install Google Chrome
sudo apt-get install google-chrome-stable

NOTE:If you don't need need the stable version then install google-chrome-beta or google-chrome-unstable packages by giving
sudo apt-get install google-chrome-beta

OR
sudo apt-get install google-chrome-unstable

Comment: Thanks for the replies. I don't need to be stalked by Chrome, I am using Firefox and happy with it.

Install Google Chrome Nag


What's the correct interpretation for f1 score when precision is Nan and recall is not Nan?

Question: Given the following formula:
Precision = TP / (TP + FP)
Recall = TPR (True Positive Rate)
 F1 = 2((PRE * REC)/(PRE + REC))

What is the correct interpretation for f1-score when precision is Nan and recall isn't?
Comment: What language is this in? In Python, for example, you can't get NaN by dividing by zero, as it raises an error instead.
Comment: @J.g It's in c++
Answer: You want to interpret $2TP/(2TP+FP+FN)$ if $TP/(TP+FP)$ is NaN but $TP/(TP+FN)$ isn't. Programming languages come in two kinds for this:
Case I: NaN results from one of the variables being NaN. By process of elimination, it's FP. Therefore, $2TP/(2TP+FP+FN)$ will also be NaN.
Case II: NaN results from a division by $0$. Then $TP=FP=0\ne FN$, so $2TP/(2TP+FP+FN)=0$.
According to these answers, C++ is case II, obtaining NaN from $0/0$.
Comment: i'm more concerned about the statistical interpretation, rather than the programming semantics
Answer: Presumably the precision $TP/(TP+FP)$ is coming as NaN because $TP=0$ and $FP=0$:

If there are no false negatives either, i.e. $FN = 0$ too and the sensitivity is also NaN, then the $F_1$ score really is undefined: there were no cases where your model had any opportunity to identify any true positives whether it was good or not, though at least it had no false negatives. Sine the $F_1$ score ignores true negatives and treats them as irrelevant (so it is not really a complete accuracy measure), you have no useful data for calculation of $F_1$.
If there are any false negatives, i.e. $FN \gt 0$, then you can take the $F_1$ score to be zero: your model failed to identify any true positives when it could have done.  The way to see this is to note that you can write $F_1 = \frac{2\, TP}{(TP+FP) +(TP + FN)}$.
You can use the same argument as the second point to deal with the case where the sensitivity is NaN, i.e. $TP=0$ and $FN=0$ but the precision is $0$ because $FP>0$. Your model identified positives when there was no possibility of true positives, so you can take the $F_1$ score to be zero.


how to capture screen shot of packaged app in chrome browser?

Question: we are developing some packaged app on chromium os... and the requirement is to capture the screen shot of my packaged app gui...
there is no chrome api in chrome apps to capture it from app itself...
but there is an api chrome.tab.captureVisibleTab in chrome extensions. but that too take screen shots of browser tabs only not of the packaged app
please help how to take screenshot of app ui?
Answer: See chrome.desktopCapture if you want to take a screen shot pragmatically with your app.


Crystal Reports, image not displayed in c# report viewer

Question: I have a report that requires a different image to be loaded whenever a new report is printed. My entire report loads and displays just fine except for the Picture object. I'm not using a dataset and I'm not loading from a database. I set all the fields manually in my application. In the report designer I set an OLE Picture with a hyper link to a file. The file URL is loaded from a parameter field that points to the image to be loaded.
When I view my report in the c# crystal reports viewer my report looks fine except the image doesn't change. It continues to show the placeholder image I had set. When I click on the image in the report viewer, it loads the windows image viewer with the correct image. I hope someone will be able to help with this. Thank you very much in advance.
Answer: I don't think clicking on a picture in a crystal report normally launches the image in your default associated application. Have you set the ole object's hyperlink attribute by mistake? (instead of the graphic location attribute).


Print message to spring shell while the shell is starting up

Question: I'm using spring shell and I want to add some "loading.." message so when the user open the shell the message will shown immediately (on the shell).
My idea is to add "ECHO loading" command to the batch file but I can't figure out how can I add some print command to the batch file that is created using
appassembler-maven-plugin. There is a way to add this ECHO to the batch file from the pom?
This is the plugin I use to create the batch file in pom.xml:
<code>        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>appassembler-maven-plugin</artifactId>
            <version>1.8.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>assemble</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <repositoryLayout>flat</repositoryLayout>
                <repositoryName>lib</repositoryName>
                <assembleDirectory>target/lang</assembleDirectory>
                <useWildcardClassPath>true</useWildcardClassPath>
                <programs>
                    <program>
                        <mainClass>org.springframework.shell.Bootstrap</mainClass>
                        <id>cs</id>
                    </program>
                </programs>
            </configuration>
        </plugin>
</code>
Is there a way to add the ECHO command to the batch file permanently?
Or, if that does not work, is there a way to print message to the shell that will appear between the time the shell is opening to the time the shell actually ready for use?
Comment: I am not understanding how this code has anything to do with Windows Batch Files. Seems like the batch-file does not apply to your question.
Answer: I don't think that batch file is the way to go.
I would try doing it be creating a method that calls Bootstrap:
<code>public static void main(String[] args) throws IOException {
        System.out.println("Your message");
        logger.info("Or mybe this way if you set the logger to print to console");
        Bootstrap.main(args);
    }
</code>


Is it safe to give credit card first 6 numbers+ last 4 over email?

Question: A company that I had previously had a subscription with and cancelled continues to charge me, so I contact their support team and they say that their system shows me to be cancelled. They have asked me to give the first 6 digits and last 4 of my credit card over email after a long back and forth. Is this safe details of my credit card to send or should I do it phone or perhaps just contact my bank. The company is SCRIBD, a reading service btw.
Answer: No, you shouldn't. Due to too many data leaks, even sending a part of the credit card number is not safe.
Due to USA poor electronics subscription regulation,  one who wants to cancel the Scribd account online need to go through a series of deceptive option screens. IMHO, you should just go back to your Scribd account and reinspect the cancellation process, make sure you don't miss every step as pointed up by the article given (note: interface might change since the article is written in 2015).
If this doesn't work, it is easier to call your credit card company to revoke the consent or get a new card.
Answer: In Poland such things are called "soup made on nail". A deception that make you believe the other side have all the ingredients and you just need to provide small detail. While in fact they have none and you provide them with everything but they leave the impression on by veryfing "they have it" by giving you back what you just told them.

Credit card numbers have 16 numbers. You give them 10 of them. Of which 4 are the last ones. Next time they could say "If you are owner of the card ending in 1234 please provide Next to last 4 numbers".
If they are billing your CC they already should have your CC number. Veryfing you based on those number WOULD be ok if there was trust in that company. In your case I'd say there is none so I would avoid such method of verification.

In general, if cancelation of any payment is fruitless on the vendor side I just go straight to my bank and cancel/block payment there. It's the same work as going through identical process on vendor side (of which I know don't work).


Does the Spanish dictionary work on Ubuntu 15.10?

Question: I was wondering if someone has tested dictionaries on Ubuntu 15.10? I have found old posts and installed the Spanish dictionary from here but it wont let me choose it and I cant correct my documents written in Spanish.
Comment: Searching for "Spanish" at the link you gave, I see two dictionaries.  Which one did you use?
Answer: Set up the system wide language settings as explained in the accepted answer here:  How to install a LibreOffice Dictionary (Spelling Check, Thesaurus...).
I did this and then went to Tools -> Options -> Language Settings -> Writing Aids and clicked the Edit button for writing aids.  Selecting Spanish (Spain) now shows an entry under Spelling.  It was empty before changing the system wide settings.
Then close the options and create a new paragraph style.  In the Font tab of the paragraph style, change the language to Spanish (Spain).
Now in paragraphs using the new style, it underlines misspelled words in Spanish.  For example if I enter "Hello", it is underlined as misspelled, but if I enter "Hola" it is not.
My system is Ubuntu 14.04 with LO 4.2.
See also: https://help.libreoffice.org/Common/Selecting_the_Document_Language.
Comment: Yes Jim K is right - in 15.10 you will have to go through 1 level more:
Tools -> Options -> Language Settings -> Writing aids  !  Lots of check-boxes find the combinations that works best for you
Comment: @KenMollerup, thanks for catching that.  I edited my answer to include `Language Settings`.


Send/Receive SMS on an iPad

Question: I would like to know if one can send and receive text messages on the iPad without having to bother those who are texting you to join IMs etc.
Answer: Google voice is a good option. It lets you send and receive texts from anywhere you have Internet. You get a phone number through it.
It's completely free, and you can use Google's iPhone app on your iPad. Or, you can buy GV Connect for iPad.
Comment: Google Voice is not available in my country TT.TT
Answer: Skype for iPad?
But to receive the messages you have to configure your Skype account with your mobile phone number and then you will receive the replies on it instead of the iPad.
Also, give Textfree a look.
Comment: Do your friends need to be on Textfree too in order to recieve sms?
Comment: It seems not. You receive a free number to which messages will be sent.
Answer: iMessage in iOS5 will bring about some of this, but only for other people running an iOS5 device. Viber and other similar apps to the same thing but they're even more niche.
Answer: If you own an iPhone, you can send and receive SMS from your iPhone contact number using the iPad. This can be made to work by enabling Text Message Forwarding on your iPhone.
It can be enabled by going to Settings apps → Messages → Text Message Forwarding on your iPhone and turning on the switch which appears against your iPad device in the list. You need to be signed in with the same Apple ID on both the iPhone and the iPad for this to work.
For setup instructions, you can go through the Apple Support article How to forward SMS/MMS texts on your iPhone.

Send/Receive SMS on an iPad


what is the grammatical function of 'those' and 'who' in the phrase 'those who live in urban areas'

Question: I want to know the part of speech of the words 'those' and 'who' in the following phrase:
those who live in urban areas.
because some of  my students make mistake and write 'who live in urban areas', which is most probably because they think the pronoun 'who' is  enough and they should not use the word 'those'.
Answer: Those is a pronoun.
Who is a relative pronoun.
Your students are partly right: "Who" can function as a fused relative, though it is far rarer than "whoever". (Also, I can't think of any plural examples: it is usually singular: "Who" = "The one who").
But, unlike the case of what, this is rare, and a literary usage: an example is the title Who dares, wins.
The example you give of what your students write is certainly not idiomatic, and will likely confuse a reader.


Who is Gakuhō Asano wife? What is their story?

Question: The anime features him only having a son but how did that come to happen? Him being a superhuman and all, he probably wouldn't settle down for a normal girl, or would he? What is the story there? Did he ever get married?
Comment: i bet it was Nagisa's Mom :v or maybe his "Son" is in fact his Clone :v
Answer: As far as I can tell from reading the wikia for the show, they have no mentioned the mother yet.
This is less of an answer and more of a "there is no answer" type thing.
Although I'm all for the idea of him having cloned himself into his son. That opens some very frightening possibilities and some interesting conclusions. Does he have more clones? If his son-clone turned out like that, then could the father actually be a good person that was changed by bad circumstances? I'd watch that.
Comment: What are the indicators of his son being his clone?

Spoiler: Watch the latest episode to see how the father was good then bad.
Comment: @demirb

SPOILERS: It gives a background of the father, but it doesn't mention anything regarding his family. The father did change a lot, but we don't have enough information regarding his son. The son doesn't match either the young or the old versions of his father, so it's difficult to say if they have more than a normal family bond that drives the other similarities. I'm like my father, but I'm not his clone. Unless I missed something.
Answer: I'm wondering if the principal got married, had a son, and went kind of crazy for power. Power seems to be way too important for him. Maybe his wife left because of that.


How do I generate points at the intersection of the line with each polygon?

Question: I need to generate points in the places where the line shape cuts to the shape of polygons.
Comment: The intersection of a line and a polygon is only a point if the line only touches the exterior.  In the example shown, the intersections are lines, not points. You'd need to further process those lines to points, and then choose the right point.
Answer: As @Vince explained, the intersection of a line and a polygon is only a point if the line only touches the exterior. If the line crosses into and out of the polygon, the intersection is a line.
What you want is the intersection of the lines with the polygon boundaries. Here are two different ways to achieve this.

Convert the polygons to lines, using the Polygons to lines tool. Take the intersection of the two line layers.

-or-

Take the intersection of the lines and polygons (which gives you a layer of lines). Use the geometry by expression tool to extract the startpoints and endpoints of those lines. Run geometry by expression twice, once with this expression: start_point($geometry), and once with this one: end_point($geometry).
Answer: you can use st_intersection between the line and the group of polygons, then your result will be this set of points you need.
Answer: You can achieve what you want using a virtual layer.
Let's note that this approach assumes you have simple polygons only.
The idea is to compute the intersection between the line layer and the exterior ring of the polygons. Since both are lines you will typically end-up with a point at the intersection
Go to Layer / Add layer / Add-Edit virtual layer and enter the following expression
select st_intersection(l.geometry, st_exteriorring(a.geometry))
from myLineLayer l, myPolygonLayer a


what is the easiest method to plot a temperature in my pc?

Question: After a lot of learning, I'm launching a reballing business and I feel the need to have a realtime plot of the temperatures involved (ideally 3 or 4) and I have an arduino uno and a few K type thermocouples, I was researching the subject and saw a lot of different approachs, most of them use arduinos to send serial data to a pc port, then from there they process it with phyton, other guys matlab, some use ms excel plus a free add on in vb for apps. etcetera, and now after some reading I feel overwhelmed by all the different methods, so I wonder, perhaps I'm already losing perspective here? may be there is a simple method I can use and KISS way of get it done? thank you.
Comment: I don't think this question is concerned with robotics... :)
It is about programming/electronics
Answer: Looking for a open (free) source alternative is it normal to feel overwhelmed since the programs, that you can use, are really many.
Personally when I need to plot soma data coming from Arduino or Teensy on my PC I go through one of those ways:

If I want to use a programming tool Processing could be really easily implemented to show what you want. It has the same language as Arduino and the same environment. Take a look in the examples. There you can find a program that suits your needs. Since the language is the same as Arduino you have a very high portability and reconfigurability;
If I don't want to program anything, but just plot some values without loosing time, then I use Scilab. You don't need a license like Matlab, and fr plotting you have a lot of tools. This could be the way you want to go. In the Scilab package configuration there is package that listens to the serial port. You just need to write a small script to save in a array and then plot them. To open a serial port you need just three functions, really strightforward. I used it for controlling a robotic arm. I've formatted my PC due to a hardware failure, so I m sorry I cannot send you an already created script made by myself;
There are other options like gplot, octave or exceel. But if you don't want to spend more time and need a very fast solution I would go for the step #2;

Regards
Answer: Do you need to use the Arduino?  Because if all I wanted to do was get temperature readings on the computer, I would use an off-the-shelf data acquisition device.  For example LabJack, Phidgets, something from National Instruments, or any number of others.  There also seems to be a large number of dedicated USB temperature sensors that are not too expensive.
These may be more expensive than something completely custom with an Arduino, but will be the simplest and most straight forward.   (Because you don't have to write code in 2 places.)  That is unless you are already very comfortable with the Arduino.
On the PC side, there are probably almost as many ways to accomplish this as there are languages.  It is hard to give advice without more background info on your requirements and personal capabilities.  (Windows or Linux, do you want a nice GUI or bare bones, do you want to store historical data, do you want it to be a desktop widget or regular application, what level of programmer are you, etc.)
You should use the tools you are most comfortable with.  For example i know people who would do this on Linux in a few lines of bash script with gnuplot.  And others who would use matlab on Windows.  Personally, I'd probably go with Python and matplotlib.
Comment: lol, bash script and gnuplot? not yet at that level, just a power user of both worlds so far, I'm ok with arduino, not very comfortable yet, and those usb gadgets seem a nice way to do it, however, I forgot to mention some spending restraints at work here, I'm trying Dave advice and some personal juice now, still your answer does provide some more insight, a light at the end of the tunnel, for that, thanks!
Comment: I forgot to mention, I'm familiar with atmel micros, unfamiliar with processing language, and I have some know how about atmel instruction sets, just never had the need to plot anything in my life, and now I have three projects with the same requirements. lol. I appreciate all insights you all brain peoples out there can give.
Answer: Pyqtgraph for python is made with OpenGl and its blazing fast compare to Mathplotlib or other that are using processor to draw... I was really happy with Pyqtgraph, and it is made for ploting real time plots.
Answer: DatPlot is an absolutely fantastic tool for plotting data and browsing through it, and I use it heavily when I want to quickly visualise and browse some data. I think it perfectly fills in a gap that exists between spreadsheets (such as excel) and general purpose computing packages (such as MATLAB, Scilab etc), in that it's great for exploring the data (zooming in and out, panning, selecting - which is something that spreadsheets utterly lack in my experience), and at the same time very simple and dedicated to one task (unlike MATLAB, scilab) and hence is quick to download install and use.

Obviously, you're still going to have to get the temperature data into your PC. If you have an off the shelf data logger, then great. Otherwise, in my opinion, an Arduino (or other microcontroller) would be a very simple solution - just get it to regularly sample your sensor and then send temperature (and optionally time) via the serial port. You can then use a program such as RealTerm (don't be overwhelmed by the UI) to automatically capture what's being sent via the serial port and save it to a file that you can then directly open in DatPlot. In RealTerm, the Capture tab allows you to just dump whatever is coming from the serial port directly to a file.


To press ones forefinger onto someone's shoulder

Question: What's the expression for touching someone with your forefinger or hand to, for example to get their attention, to wake them up, or to mark your presence.
Comment: Normally that's referred to as "tapping on the shoulder" -- "He tapped Fred on the shoulder to get his attention."
Comment: Or you can touch someone on the shoulder.  That is more gentle than *tap* and it accomplishes the same thing.  It is understood that it is done to get their attention. ...  Now, for waking someone up, you may need to *shake* his shoulder.
Answer: Tapping is probably the best answer, but you can also poke him with your finger, just to give you another option.
Comment: @habibhassani - I just noticed I didn't write my comment very clearly.  I meant to say that "poking" indicates that it is annoying and done face to face.  "Tapping" is more innocuous and could be from the side or the back.
Comment: This is the best one if you want to express that it is annoying to the person on the receiving end.  This one is done face to face.
Comment: @aparente001 thanks for the supplement
Comment: @aparente001 i got the annoying part but not the face to face, so thank you for clarification.
Comment: @habibhassani - and then "jabbing" would be *incredibly* annoying.  Also done face to face.
Answer: It depends how, and where on the body, you touch them. There are three main ways to do do this

Tap, to give one or more light blows, usually on the shoulder.
Prod, to jab with a finger or an implement such as a ruler or a stick. The jab can be gentle or it can be harder (sometimes referred to as more sharp), it's still a prod.
Stroke (3rd definition of the noun,1st definition of the verb), this is a gentle moving of the hand or fingers over a part of the body, usually an arm or hand. Strokes on other parts of the body are more intimate.

Examples of the usage are

"I gave him a tap on the shoulder"
"I prodded his arm sharply with my pen"
"I stroked her hand gently"

There are many ways to add subtle changes to these statements; there's probably enough material for a book, and the book would almost certainly miss some things. This is just a starting point.


Flexagonal flexagation

Question: Being programmers, watching us flex aren't very interesting. Today we change that! In this challenge you will lex and flex hexaflexagons.
About
For a video introduction, watch viharts video(s) on flexagons
A flexagon is a shape that you can flex to reveal faces other than the top and bottom one; we are making a hexahexaflexagon, which has 6 faces. See the image below on how to fold a hexahexaflexagon out of a strip of paper.

A shows both sides of the strip. The two white triangles are glued together.
This is how you would flex it:

Below is a diagram of possible states and their relationships:

The colored circles represent the 6 triangles with the same number from the first image. Each of the circes have two colors- the bottom most represent the back face (what you would see if you where to flip your flexagon around), which you don't have to consider in this challenge.

The gray circles in the background represent how you can flex your flexagon in any given state: there are 4 different ways to flex it, we call these Left, Right, Up and Down. You don't actually flex in these directions, the important bit is that some are opposite to each other.

If you are in the center you can use Left and Right to go to the other center ones. To get out of the center you use Up and Down. If you aren't in the center you cannot use Left or Right.
Left/Down = clockwise
Right/Up  = anti-clockwise

Challenge
Create a function or program that take as input what should be on the 18 front faces and the 18 back faces of a flexagon, a sequence of left, right, up and down flexes, and return the 8 visible faces after the flexes.
Elaborate example computation:
flex "hexaflexaperplexia"
     "flexagationdevices"
     [Right, Right, Left]

Divide a strip of paper into 18 triangles:
1/2\3/1\2/3\1/2\3/1\2/3\1/2\3/1\2/3   Front
4/4\5/5\6/6\4/4\5/5\6/6\4/4\5/5\6/6   Back

Write "hexaflexaperplexia" on the front of the paper strip:
1/2\3/1\2/3\1/2\3/1\2/3\1/2\3/1\2/3

hexaflexaperplexia
123123123123123123
h  a  e  p  p  x     Face 1, Initially the front face
 e  f  x  e  l  i    Face 2, Initially the back face
  x  l  a  r  e  a   Face 3, Initially hidden

Write "flexagationdevices" on the back of the paperstrip:
4/4\5/5\6/6\4/4\5/5\6/6\4/4\5/5\6/6

flexagationdevices
445566445566445566
fl    at    ev       Face 4, up from 3
  ex    io    ic     Face 5, up from 2
    ag    nd    es   Face 6, up from 1

Flex it [Right, Right, Left]
  The initial visible face is 1: "haeppx"
  flexing Right ..
  The current visible face is 2: "efxeli"
  flexing Right ..
  The current visible face is 3: "xlarea"
  flexing Left ..
  The current visible face is 2: "efxeli"
  flexed [Right, Right, Left]!

outputting "efxeli"

Example implementation: http://jdoodle.com/a/18A
Input and expected output:
> hexaflexaperplexia flexagationdevices RRL
= efxeli

> loremipsumdolorsit hexaflexamexicania RUU
= riuort

> abcdefghijklmnopqr stuvwxyz1234567890 UL
= I can't flex that way :(

> abcdefghijklmnopqr stuvwxyz1234567890 RRRRLLUDDUUUULDD
= uv1278

Rules

You may take input and return output in any reasonable way
If the input is impossible, you should indicate so in some way that is distinct from regular output
Standard loopholes apply
This is Codegolf. Shortest code in bytes win.
Answer: Haskell (Lambdabot), 270 234 bytes
(!)=((map(snd<$>).groupBy((.fst).(==).fst).sortOn fst).).zip.cycle
o n(a,b)|n>1||b<1=(mod(a+[-1,1,0,0]!!n)3,mod(b+[0,0,-1,1]!!n)3)
(x&y)d|(g,h)<-foldl(flip(.))id(o<$>d)(0,0)=([0,1,2]!x++[3,3,4,4,5,5]!y)!!([0,5,1,1,4,2,2,3,0]!!(3*g+h))

Usage:
> (&) "hexaflexaperplexia" "flexagationdevices" [1,3]
"exioic"

[0,1,2,3] = [left,right,up,down]

Thanks to @Damien for a lot of bytes!
Comment: What's the use of `|b/=0=[]!!1` ? You can save a few bytes rewriting some functions in pointfree style : `\(a,_)(b,_)->a==b` -> `(.fst).(==).fst` , `(!)=(q.).zip.cycle`
Comment: OK, you could simplify it with `o n(a,b)|n>1||b<1=(z$a+[-1,1,0,0]!!n,z$b+[0,0,-1,1]!!n)` this will throw an Non-exhaustive patterns exception
Comment: @Damien `|b/=0=[]!!1` just throws an exception if you try to do a impossible flex

Flexagonal flexagation


Web API for Most Popular Items and Trending Items in Sharepoint 2013

Question: I want to create an html and display popular and trending items from my list. How can I get this information, is there an API for that?
Answer: There is something built in (at least in my environment SP2013 Enterprise).
See here:

Does this help?
Comment: Thank you Patrick. But this is not the solution which I want. I think above solution will give me an excel file. I don't want excel file. I want an API to explicitly display trending and popular items on my UI. Can you please give me solution for that?
Comment: The solution above does not give you an excel sheet. It is an actual webpart which displays you the popular items. You can change the UI with the existing display templates or create one on you own. Maybe just give it a shot an test it.