Where is the original Dantzig Simplex 1947 paper?

Question: I see from here and many other sources that Dantzig invented the Simplex method in 1947. After much searching, I found that the earliest publication is this in 1956. Does anyone know where the original 1947 paper is?
Answer: Introduction
When Dantzig devised the algorithm, he was working at the Pentagon and thus many things would have been designated as classified in the military. There are a few more details provided in the book "How Reason Almost Lost Its Mind: The Strange Career of Cold War Rationality" by Erickson et al. (2013) but I need permission from the second author before I can quote any part of that.
A number of Dantzig's documents published a few years after 1947 concerning the simplex method are publicly available; for instance, Dantzig, Orden and Wolfe published the generalized simplex method in 1954, but it is unclear whether the original paper has since been declassified and published publicly.
Most Important Finding
In "Dantzig, George B. (1914–2005)" by Cottle, Eaves and Thapa (2016), there is this curious reference in the following biography.

Selected Works
1947. Prospectus for the AAF electronic computer. Unpublished manuscript.

 AAF = United States Army Air Force.
I am not certain if this really was Dantzig's publication, but if so, then it suggests it won't be publicly available. However, there is a strong hint to this in the paragraphs I quote below.

Dantzig nonetheless turned down a position in mathematics at UC Berkeley for the greater financial security of a position at the Pentagon. There he undertook the challenge to "mechanize" the planning process. War planning required the coordination of an entire nation and yet was executed with desk calculators; the need for mechanization was clear. To this end, a group in the Air Force was organized under the name Project SCOOP (Scientific Computation of Optimum Programs) and headed by M.K. Wood. Dantzig was a principal.
Two movements suggested that progress was possible: Leontief's (1936) work and the emergence of the computer; indeed, Project SCOOP arranged for Pentagon support of computer development (see Dantzig 1947). In early 1947, Dantzig formulated the general statement of a linear program. In June of that year, he learned from T.C. Koopmans, who had been studying transportation problems  (Koopmans 1947) that economists had no algorithm for solving a linear program. By July Dantzig had designed the simplex method.

History
There are several journal articles that describe Dantzig's invention and discovery of the method, some including his own; for instance, this unclassified technical report titled "Impact of Linear Programming on Computer Development" by Dantzig (1985).

Origins of the Simplex Method, Summer 1947
The first idea that would occur to anyone as a technique for solving
a linear program, aside from the obvious one of moving through the
interior of the convex set, is that of moving from one vertex to the next
along the edges of the polyhedral set. I discarded this idea immediately as
impractical in higher dimensional spaces. It seemed intuitively obvious
that there would be far too many vertices and edges to wander over in the
general case for such a method to be efficient.
When Hurwicz came to visit me at the Pentagon in the summer of 1947, I
told him how I had discarded this vertex-edge approach as Intuitively
inefficient for solving LP. I suggested Instead that we study the problem
in the geometry of columns rather than the usual one of the rows -- column
geometry incidentally was the one I had used in my Ph.D. thesis on the
Neyman-Pearson Lemma. We dubbed the new method "climbing the bean pole."
It looked to me efficient. [...] Apparently, in one geometry the
simplex method looks efficient while in another it appeared to be very
inefficient! Thus the simplex method was born in August 1947.

Other potential avenues to track the paper
I also found a comprehensive list of Dantzig's publications, talks and correspondences, where of interest are

box 10, folder 19 Letters to Laderman Simplex Algorithm Dec 1947/Sept. 1947
box 10, folder 21 First Simplex Method Computations Summer 1947
box 10, folder 22 AMC SCOOP Supply Procedure October 1947
box 10, folder 23 Outline of Talk Given BLS (Cornfield) 6/26/1947
box 16, folder 29 Copies of correspondence with Von Neumman 10/1/1947
box 16, folder 34 Discussion of a Max problem Von Neumman 11/15/1947.

The first two items in particular may be of greatest relevance. Unfortunately, these are all physically archived within Stanford University Library so I am not able to access them.
Comment: @Max the row-based simplex is implemented in SoPlex (https://soplex.zib.de). You can read about it here: https://nbn-resolving.org/urn:nbn:de:0297-zib-16349
Comment: This makes me curious about the "geometry of rows" hinted at... what would a row-based simplex method look like? Even if inefficient, it seems interesting to learn about.
Comment: This is a great answer @TheSimpliFire. I really enjoyed reading that. Thank for putting all these valuable information together.
Comment: Nice. But apparently inconsistent quotes from different sources.  "By July Dantzig had designed the simplex method.".  "Thus the simplex method was born in August 1947."
Comment: @MarkL.Stone The vast majority of literature cite August 1947, including Dantzig himself (see [this interview](https://www.informs.org/Explore/History-of-O.R.-Excellence/Oral-Histories/George-Dantzig)). Perhaps July 1947 was meant to be his initial design/conception, which was then fully developed in August, but I haven't found any more documents to explain this.
Comment: Consider also: "box 13.1, folder 28 Prospectus for the AAF Electronics prog. comp. June 1946" https://oac.cdlib.org/findaid/ark:/13030/c8s75gwd/dsc/
Answer: Another paper you may want to look at is the Project SCOOP (Scientific Computation of Optimum Programs) report, circa 1951. SCOOP was the project under which Dantzig did his first LP work. This report is accessible here:
https://www.informs.org/Explore/History-of-O.R.-Excellence/O.R.-Methodologies/Optimization-Mathematical-Programming
Answer: The earliest Dantzig reference I know for the simplex method is:

George B. Dantzig, "Maximization of a Linear Function of Variables Subject to Linear Inequalities." In Activity Analysis of Production and Allocation, Tjalling C. Koopmans, ed., Wiley (1951) 339-347.

Although this volume was published in 1951, it is based on presentations given at a conference in 1949, and Dantzig's footnotes on the title page make it clear that his investigations of the simplex method dated to 1947.
This and other early references from Dantzig's work at the RAND Corporation are given in The Origins of a Practical Simplex Method, a talk I contributed to a celebration of Dantzig's "100th birthday" at the INFORMS Annual Meeting in 2014.
Answer: Just to supplement a great answer by @TheSimpliFire, the chapter "Origins of the Simplex Method" by Dantzig in "A history of scientific computing" (June 1990), also gives some idea of what work was being done in the field around the time he developed his approach.
A reference provided in that chapter is to:

G. B. Dantzig, "Linear Programming," in Problems for the Numerical
Analysis of the Future, Proceedings of the Symposium on Modern
Calculating Machinery and Numerical Methods, UCLA (July 29-31,1948);
Appl. Math. 15, National Bureau of Standards (1951): 18-21.

The National Technical Reports Library in 1951 mentions that it includes four papers presented at the Symposium on Modern Calculating Machinery and Numerical Methods, held in July 1948 one of which is titled Linear Programing by George B. Dantzig. That report can be found here.


could I mount a different manufacturer brand rotor to use with my brakes?

Question: I've a tektro draco hydraulic brakes on my mtb and I would like to know if it is possible to mount a different brand rotor to use with my brakes?
Answer: The brand of brake doesn't matter. The only variables you should care about are:

Rotor diameter. You should probably get the same size as the old one; for a different size, you'll need an adapter to reposition the brake calipers.
The way the rotor attaches to the hub. Most of them are held on with 6 bolts, but a few use the "Centerlock" attachement which looks like this:
Comment: Could I use any adapters?, or do I need the ones that matches the calipers brand?. I would like to upgrade to 200mm and is hard to find those tektro draco adapters.
Comment: You have to match the caliper brand.  It's the fork/frame end of the adapter that is standardised, but the caliper mounts tend to be proprietary.
Comment: @cmannett85: they're not standardized, but I *think* there's only a small number of variations.
Comment: @yeforriak: I'm not sure. You should post a separate question, maybe someone will know. Before you do, measure the distance between the mounting bolt holes (you might need measuring calipers).
Answer: As long as the bolt pattern is the same and the rotor is the same size, it should be fine.
Answer: This is a separate answer only because I can't vote or comment on other's answers yet.
Speaking directly to the original question... yes - it is possible.  I have a winter set of wheels with a rotor by a different maker and it is a center lock mount vs. a six-bolt mount of my regular wheels.  No problem at all and it is one of the main things I like about disk brakes.  With rim brakes I would have to adjust the brakes each time I did the switch-a-roo unless both sets of wheels had exactly the same width.  Since the winter wheels have studded tires I make the switch on clear/dry days in the winter as well.


Wallpaper in unheated entrance way

Question: My wife suggested that we wallpaper a small entranceway to our home.  It is a fully-enclosed space (about 3 ft by 3ft) beyond the front door - but there's a second (glass) door to enter the living space.  This small room has no vents, and therefore does not receive any heat/air conditioning.  It can get very cold in the winter and very warm in the summer.  My concern is whether the wallpapering would hold up to these temperatures.  Thoughts?
Comment: I wouldn't worry, since i've had to remove the stuff before (not easy).
Comment: I wouldn't worry about heat/cold. I'd worry about humidity.
Comment: Impermeable wall covering can trap condensation that may become an issue.
Answer: Your entryway gets heat from the house. Not enough for you to call it warm, but it will be warm compared to the exterior, and that is what is important.
Secondly, the room might not be heated, and the windows may leak, but it is also very helpful if the walls are insulated.
The issue is not temperature, it is moisture. Go into the room on a wet winter day and feel the walls. Is any part of the wall wet? Go into the room on a super cold winter day. Are the walls damp or icy? Check near the windows and down low and in the corners where air moves the least and cold is nearest by. If there is dampness, then the wall paper has no chance because the moisture will release the glue even if the paper is vinyl. But, if the walls remain dry, then your wall paper should be fine.

Wallpaper in unheated entrance way


What are the verb conjugation names called in Latin?

Question: What are the terms in Latin for the Latin verb conjugations? I would like to also know the Latin for the mixed conjugation (or if preferred that known as the io sub conjugation) and any term for verbs not in these conjugations, those irregular verbs.
Comment: I asked this question with an understanding that contemporary classical Greek writers recognised 3 conjugations, and the meaning of declinatio may have changed over time.
Comment: I forgot to include that the reason for this question is because I wish to be able to replace all the Non Latin headings in a Latin reference grammar with Latin headings.
Answer: I have found a partial answer in Lingua Latina where there are the recognised modern conjugations and these are described as four declensions of verbs called conjugations.
Declinationes verborum sunt quattuor, 'coniugationes' quae vocantur:
Coniugatio prima      1. ~are
Coniugatio secunda    2. -ere
Coniugalio tertia     3. -ere
Coniugatio quarta     4. -ire
Ut 'sum sumus* declinantur verba quorum Infinitivus desinit in -esse, ut ab-esse...
And from scans of 17th Century Latin books by Martin-Luther-Universitat Halle-Wittenberg comes the following.
After seeing the above terms in Hans Oerberg's Lingua Latina per se Illustrata, I've now been able to find multiple usages elsewhere in searches such as in online forums and also in other books for the first four conjugation terms.
This includes the ablatives De Prima Coniugatione, De Secunda Coniugatione, De Tertia Coniugatione, De Quarta Coniugatione. For example these are found in the Latin Grammar Compendium Grammaticae Latinae MDCLXXXVI (https://digitale.bibliothek.uni-halle.de/vd17/content/pageview/11399863 )
Titles for specific irregular verbs are given in the Compendium Grammaticae Latinae of 1651 Compendium Grammaticae MDCLI   Compendium Grammaticae Latinae : ab Ipsis Grammaticae Authoribus adornatum, & singulari studio in usum Scholasticae Iuventutis, ita digestum, Ut Nec Libris Alphabeticis, nec Donati paradigmatibus amplius opus sit pueris, qui eo utuntur   ( https://digitale.bibliothek.uni-halle.de/vd17/content/structure/8784313 ) What can be described as the heading of the third book of this compliation by Casparum Rotelium of Frankffurt is ParadigmaTa Declinationum Et Conjugationum: Tam Regularium quàm Irregularium . For the four conjugations of verbs, in this book, they are called Primae Conjugationis, II. Conjugationis, III. Conjugationis, IV. Conjugationis and as part of, but after other individual verbs, Inquio, III Conjugationis.
The titles for the individual verbs are usually of the form of the form Conjugatio verbi fero, Conjugatio verbi sum, Conjugatio verbi possum, etc
Based on these it is not much of a stretch for a title "Irregular verb conjugations"  like Coniugatio verborum irregularium, or alternatively  De coniugatione verborum irregularium .
Comment: Quick text searches within De Lingua Latina by Marcus Terentius Varro and Attic Nights by Aulus Gellius wasn't effective. Slowly making way through these texts commencing with Attic Nights. Book II XXV of Attic nights showed use of term inaequalitas declinationum in specific contrast to proportionem based on Greek terminology, but going to see if there is consistent and repeated usage of any terms.


Why is Scottish not an accepted culture in Great Britain?

Question: I started my game as England and formed Great Britain in 16th century. I assumed that Great Britain is a cultural union and would deem all cultures in British group to be accepted. However, Scottish remained unaccepted. Can someone shed some light on this? I have Common Sense expansion, if that is relevant.
Answer: Since patch 1.14 Cultural union isn't any longer tied to country tag, but can be claimed once your country reaches Empire level. If you don't have Common Sense DLC active, the limit is owning at least 1000 development.
Source: changelog for 1.14 (link)
Comment: I see, so need to be Empire level with Common Sense and at 1000 development without?
Comment: @SMeznaric Yes, as far as I know. I got this information from 1.14 changelog (might as well include that as a source for the answer) which I believe is correct.
Answer: Because Great Britain isn't an Empire, it's a kingdom level national title.
A cultural Union (now) requires you hold the Rank of Empire either through country decision (It'll specifically say it raises you to Empire Level, like Ottomans or Japan, or fixed rank Empire government-type like Ming's celestial empire) or having 1000 or more total development will let you simply declare yourself an empire, which grants a cultural union of what ever your primary national culture group is.
Comment: You forget to mention that the 1000 development decision to gain rank empire require you to have 75 positive prestige. Ditto for kingdom (going from duchy to kingdom which is one rank lower than empire) also require you to have 50 positive prestige and 300 development.


Is it true that FPGAs and DSPs are widely used for modulation and demodulation of signals?

Question: I have to write a thesis about digital communications, and I don't want to write something stupid in it. I also wrote that "most of the digital modulations and signal processing nowadays are done via software". So, are these sentences true?
Thanks a lot
Comment: I suggest you read a lot more on Google Scholar before you write unless that's into a search engine  ;)
Comment: Name a platform that does complex digital anything that doesn't run on software. There's not many. Maybe only one: an FPGA. Meaning that doing something on an FPGA doesn't count as doing something in software.
Comment: In practice "Software Defined Radio" tends to loosely mean "DSP Radio" regardless if that's done in a fixed operation numerical processor, a flexible one like an FPGA, a programmable DSP, or a programmable general purpose processor.  But to say that most digital modulation is done by "software" seems false, at least in terms of "stored program microcomputer" type software.
Answer: It is true, that "FPGAs and DSPs are widely used for modulation and demodulation of signals in communications". That means, that the data link level in a canonical OSI model is implemented purely in hardware or with a strong hardware support. The reason for this is that modern high-speed communications require the processing speed, that a pure software implementation can not support.
Here you have to take into account, that, backed up by wikipedia, "a digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing". That means that a computation-intensive operations are performed with the help of specialized hardware as a part of a DSP (mainly, hardware multiplication).
An obvious example is GbE, where you have to transmit 1 billion bits per second. And even for that, modern FPGAs include dedicated hardware modules called transceivers (an example for Intel).
In a simpler cases (i.e. slower interfaces), the hardware implementation of a low-level modulation-demodulation is still much preferred. The reason for that is that to keep the link up you will need to serve it constantly, which can potentially occupy the most of the processor clocks, when implemented as a software.
It follows, that the statement "most of the digital modulations and signal processing nowadays are done via software" can be considered false.


How do you level 1/2" x 6" flooring planks?

Question: We have a 1920's house with some 1/2" X 6" planks. Unfortunately the floor is in quite rough shape with finger wide gaps in some spots, I started to attempt to sand and flatten it but I think it will be too much work. That said, would the proper course of action be to put down some 1/2" subflooring (particle board or plywood tongue and groove) first. Screw it down then lay the laminate over top? If not what would be the correct thing to
Answer: If your subfloor is only a 1/2 inch thick and partially rotten you need to replace it. Even if it were in perfect condition that's not thick enough for laminate flooring, it will droop and bounce like walking on sponge cake. Cut out your floor boards, true up/replace/sister your floor joists using a site laser or string line and power plane if they need it (and I'd bet you a shiny nickel they do)especially if the joists are under the span load limit, here's a tutorial on span limits:
http://www.awc.org/technical/spantables/tutorial.php
It looks daunting but its not as bad as it looks. If you're still fuzzy just go to your local building center and they can usually calculate loads and spans for you. Once you've got that figured out, sheet with 3/4 t&g cdx. Run a bead of PL on the joists to fill and small voids and bind it all together. Here's a pretty thorough link from a sheeting manufacturer.
http://buildgp.com/wood-products-installation-tips
Hope this helps!
Answer: As long as your floor is "flat" then you really need to follow the install advice for the type of laminate you are installing.  Some laminates require nothing, some a pad.
If your floor has a lot of damage and bumps then you probably want to patch it with a compound like floor leveler.  You don't want to have large potmarks (anything greater than an inch) in your floor and leave it thinking the pad and laminate will cover it.
Comment: There are quite large gaps between flooring so I dont think I can use a floor leveling compound. Currently there is not a half inch difference in the floor, however, I have cut and laid the laminate and I am not happy with the movement in the floor.
Comment: There are gaps with nothing underneath?  Do you have any pictures?
Comment: Just wood planks over the joist, there is about a finger between some of the more rotten spots. I don't think I can upload images.
Comment: I would use use wood filler or floor leveler.
Comment: I was told by staff that sold the floor leveler that the gaps between planks were too large.
Comment: You can fill rather large gaps with a floor leveler like - http://www.dap.com/product_details.aspx?product_id=341
Answer: Using plywood or MDF to flatten the floor and then using laminate might rise the entire floor a bit too much. You might be better off renting a drum sander and sand the entire floor to level it.
Then use damp proof pvs, underlay and then your laminate on top.
Answer: Given what you have, I'm going to beseech you - STOP sanding, you're only making too-thin flooring even thinner. If you keep going, you may fall through.
Were it my house or project, I'd lay 3/4" tongue-and-groove OSB (Oriented-Strand Board) down over the existing planks, NAILING it down with ring-shank nails (no screws). It may take some doing to select the correct-weight hammer. After the OSB is down, then lay your finish flooring on it.
For most things, I like to avoid OSB. For this, though, it's almost the perfect material.


How do I remove the glow from particles

Question: I've setup a plane with a particle emitter system. When I render the footage and the particles are glowing. Where do I find the settings for that?
Comment: You're rendering the particles as halos (the default). You can render a sphere object for every particle if you set the render type to "Object" in the particle settings, then select a sphere object in the dropdown.
Answer: As mentioned by CharlesL,
that glow is caused when the particles are rendered with Halo selected in Particle settings > Render:

From the wiki:

Particles may be rendered as:
Halos (for Flames, Smoke, Clouds).
      Meshes which in turn may be animated (e.g. fish, bees, …). In these cases, each particle "carries" another object.
      Strands (for Hair, Fur, Grass); the complete way of a particle will be shown as a strand. These strands can be manipulated in the 3D
  window (combing, adding, cutting, moving, etc).

To render a surface, you can change the rendered type to Object (to render a copy of an object in place of the particle) or Group (to randomly select the object from a group of objects)
You can change the halo settings by adding a halo material to the emitter object and changing the Material setting to the appropriate value in Particle settings > Render
The other options are

None
fairly self-explanatory, do not render particles
Line
Render a line along the vector of the particle
Path
Used with hair particles
Billboard
Render 2D planes at a fixed angle to the camera

How do I remove the glow from particles


Finishing basement... level floors with SLC or install stud wall first?

Question: Basement floor isn't too far off... wondering if I should get the stud wall done first or level the floor first....
Comment: Every basement floor has waves and imperfections. Unless you have variances that are noticeable in your feet, I wouldn't bother leveling.
Answer: You will have better surface to screw/nail bottom plate working on original concrete as is. You can and should always level before getting floor done.
Answer: It doesn't matter unless it is really far off.  Also leveling isn't a must do.
Answer: I'd do the floor first. You'll have an easier time with the wall and you won't have to try to level against wooden studs.


Speed and length of the shadow relationship proble

Question: A girl of height $0.9 m$ is walking away from the base of a lamp-post at a speed of $1.2 m/s$. If the lamp is $3.6 m$ above the ground, find the length of her shadow after $4$ seconds. I calculated the ration the length of lamp-post and height of the girl which is $4:1$. But I do not know how to link the speed to shadow
Answer: After 4 seconds the girl will be at $4.8m$ away (she moves $1.2 m/s$)
Now let's draw a straight line from the lamp to the ground that passses by the girls head
$y = Ax + B$
when  $x=0$ $y=3.6$ therefore $B=3.6$
when $x=4.8$ $y=0.9$ therefore $A=-0.5625$
So the equation becomes $y=-0.5625x+3.6$
Now to find the shadow, let's first find the intersection of that above equation to the ground, in other words when it intersects with the equation $y=0$
you can simply solve $y=-0.5625x+3.6=0$ to find $x = 6.4$
last step
$shadow = 6.4 - 4.8$
$shadow = 1.6m$

Generalization
the girl's x position's equation with respect to time is $x_1 = 1.2t$
the straight line's equation according to the girl's location can be generalized to :
$$y=Ax+B$$
at $x=0$ $y=3.6$  therefore $B = 3.6$
at $x = 1.2t$ $y = 0.9$ therefore $A = -\frac{2.7}{1.2t}$
so : $$y=-\frac{2.7}{1.2t}x+3.6$$
the intersection of this equation with $y=0$ can be found at $x_2 = \frac{3.6*1.2t}{2.7}$
Last:
shadow = $x_2 - x_1$
$$(\frac{3.6*1.2}{2.7}-1.2)t$$
$$\frac{1.2}{3}t$$
Answer: Hint: $\dfrac{x}{x+4.8} = \dfrac{0.9}{3.6}$, where $x$ is her shadow.
Comment: All thanx to Mr.Thales for his sweet theorem ;)


OCCI for non-web application

Question: I am writing a non-web application (written in java) which will allocate cloud resources. I want to make it compatible with as many providers as possible. Is it wise to use OCCI interface? Will it be too complicated?
Answer: OCCI as an open standard is indeed a good option with regards to interoperability between different resource providers.
There are quite a few OCCI implementations under development. A list can be found here:

OCCI GitHub Account

Pollux may be a good starting point for OCCI clients written in Java.
As OCCI was published last year and is still in an early adoption face, support by resource providers is just beginning. OCCI 1.1 support in OpenNebula will be followed by support for OpenStack within the next months.
It's reasonably easy to adopt an OCCI server like the OpenNebula OCCI Implementation (written in Ruby) for other resource providers as well and work is already under way to support a wider range of resource providers.
Comment: I might also mention that the next [Cloud Plugfest organised by SNIA](http://www.snia.org/cloud/cloudplugfest) will take place end of february 2012 in Düsseldorf (Germany), Tyson's Corner (Virginia) and virtual for remote participants. It's a place for programmers to get together and discuss their implementations of OCCI and CDMI.
Answer: The reality is that there is no one standard to connect to cloud providers, whether that be at the PaaS, SaaS or IaaS levels. I'm assuming you're utilising IaaS aspects here (your 'allocating resources' wording)?
OCCI is certainly one standard you can implement to cut down the number of different providers you want to support.  However, the reality is that you'll also need to write custom code (hopefully RESTFul if you're lucky) or grab custom open source components to connect to some of the cloud providers.
Comment: My starting point is OpenNebula. Which supports OCCI. It also has xmlrpc interface. So OCCI is the way to go?

OCCI for non-web application


How do I get the UUID of a bluetooth device?

Question: I need to know UUID on API 8 (2.2) or possibly 2.3.3.
As I understand the documentation, this should be allowed:
    phoneDevice = blueAdapter.getRemoteDevice(phoneAddress);
    ParcelUuid[] phoneUuids = phoneDevice.getUuids();  // Won't compile

Eclipse gives me:
"The method getUuids() is undefined for the type BluetoothDevice."
But see:
http://developer.android.com/reference/android/bluetooth/BluetoothDevice.html#getUuids()
Also, I would like to know how the UUIDs are "parceled" inside the ParcelUuid[]. In case I ever manage to get there, how do I retrieve a UUID from a parcelUuid[]? Documentation for Android bluetooth seems to be very poor, in my opinion.
What a joke!
Now I try to get it from the intent, but this too gives: *"EXTRA_UUID cannot be resolved or is not a field"*:
intent.getParcelableExtra(BluetoothDevice.EXTRA_UUID);

Comment: this will support from API level 15. whats your API level?
Comment: Hi facing same problem , in my project have provide support from android 2.3.1 , min api level 8. Please help.
Comment: Hi. Long time passed fro this post but I am now facing this exact same issue. Do you have any workaround for that (my minimum API is 10) ?Thanks for any clue
Answer: You have to use reflection to use the getUuids() and fetchUuidsWithSdp() on android version < 3. So, try the code:
Method method = phoneDevice.getClass().getMethod("getUuids", null);
ParcelUuid[] phoneUuids = (ParcelUuid[]) method.invoke(phoneDevice, null);

Answer: //this will support from API level 15 and above.
Broadcast Action: This intent is used to broadcast the UUID wrapped as a ParcelUuid of the remote device after it has been fetched. This intent is sent only when the UUIDs of the remote device are requested to be fetched using Service Discovery Protocol
    Always contains the extra field EXTRA_DEVICE
    Always contains the extra field EXTRA_UUID
    Requires BLUETOOTH to receive.
    Constant Value: "android.bluetooth.device.action.UUID"

//no way to degrade its hardware related. there is no supporting jar also. http://developer.android.com/sdk/compatibility-library.html
Comment: Okay, but API 15 is 4.0.3 released only a month ago. I need to use bluetooth on 2.2 API 8!
Comment: So, the way to do it is to create UUIDs? It's not a property of the hardware, it's just a number I make up, is that right?
Comment: @Tombola you able to get the uuid for android 2.2 to connect another device? post your solution here
Answer: Unfortunately, I don't think there is any good way to get the UUID's supported by a BluetoothDevice with API level < 15.  I guess that's why they added the new functions in API 15.
Note, from the docs for BluetoothClass

BluetoothClass is useful as a hint to roughly describe a device (for
  example to show an icon in the UI), but does not reliably describe
  which Bluetooth profiles or services are actually supported by a
  device. Accurate service discovery is done through SDP requests, which
  are automatically performed when creating an RFCOMM socket with
  createRfcommSocketToServiceRecord(UUID) and
  listenUsingRfcommWithServiceRecord(String, UUID).

So, perhaps the device class could be used as a hint as to what services will be available until you perform one of the listed functions.  Certainly it doesn't hurt to check the class since this won't require any additional bluetooth operations.
Note that the service class is also available (it is part of the device class) but this is just a general class, not a listing of specific services (like from SDP).
Answer: try BluetoothAdapter class
any question, read: http://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html
Answer: In case you can not get UUID from getUuids() method. Please try the other way.
After scanned successfully, you should receive byte[] (scanRecord), so from this result, if you can recognize UUID format you can split step by step to get correct UUID as these codes.
P/s : Important thing, you should know UUID format to get from index correctly.
// Put item into hash map
    // UUID from index 10 to 24 : 12233445566778899aabbccddeeff0
    StringBuilder mSbUUID = new StringBuilder();
    for (int i = 0; i < scanRecord.length; i++) {
        // UUID
        if (i >= 10 & i <= 24) {
            if (Integer.toHexString(
                    scanRecord[i]).contains("ffffff")) {
                mSbUUID.append(Integer.toHexString(scanRecord[i]).replace("ffffff", "") + "-");
            } else {
                mSbUUID.append(Integer.toHexString(scanRecord[i]) + "-");
            }
        }
    }

Comment: This question is from '12, and ScanRecord is part of the newer Bluetooth LE API's. This question is geared for Bluetooth Classic.


Ways to salvage a tomato plant in winter

Question: I received a tomato plant from work. It never blossomed, never produced fruit, but it grew to a fair height. My wife has ordered me to take it out of the house because it's attracting insects of some sort. Given it's October, I don't have much hope of it surviving the winter. I doubt it's even got seeds anywhere in it such that it might regrow in the Spring, but I figure I'd ask. Is there anything I can do with it short of simply planting it and forgetting it?
Answer: Stick it on the compost heap - it hasn't fruited, so there's no question of seeds, they're inside the fruits. I'm a bit curious as to why you kept in the house and didn't put it outside during the summer months, where it would have been much more likely to fruit though - they're not meant to be houseplants, though they can be grown in greenhouses. They are perennial plants in sub tropical regions, but anywhere the temperature drops below around 10 degrees C, they die in winter, and they're usually grown as annuals.
Comment: Oh I see - not worth growing tomatoes then unless you get a greenhouse!
Comment: I had it out on the porch for a while, but it's covered, so it didn't get as much sun as I'd like. I don't really have places to put outside plants at the moment. Eventually, we'd like to fence in a garden, but currently, anything outside gets consumed by the deer in rapid order.
Comment: Heh. And the deer are fast. I went ahead and stuck it in a patch of earth, just to give it a fighting chance, then went shopping. I came back and it's cropped to the ground.
Comment: Oh dear - bet your wife's pleased though!


How to prove that $\sum_{n=1}^\infty \frac{1}{n^2}=\frac{\pi^2}{6}$ without using Fourier Series

Question: Can we prove that $\sum_{n=1}^\infty \frac{1}{n^2}=\frac{\pi^2}{6}$ without using Fourier series?
Answer: Yes. The most common way to do this is attributed to Euler. It does still require Maclaurin series, however.
Consider the Maclaurin polynomial for $\frac{\sin x}{x}$:
$$\frac{\sin x}{x} = 1 - \frac{x^2}{3!} + \frac{x^4}{5!} - \cdots$$
However, note that this is a polynomial $p(x)$ with zeroes $\{\pm k\pi\;|\;k \in \Bbb N\}$, and for which $p(0) = 1$. These two properties mean that
$$\frac{\sin x}{x} = \left(1 + \frac{x}{\pi}\right)\left(1 - \frac{x}{\pi}\right)\left(1 + \frac{x}{2\pi}\right)\left(1 - \frac{x}{2\pi}\right)\cdots$$
And by multiplying adjacent terms,
$$\frac{\sin x}{x} = \left(1 - \frac{x^2}{\pi^2}\right)\left(1 - \frac{x^2}{4\pi^2}\right)\left(1 - \frac{x^2}{9\pi^2}\right)\cdots$$
Equating the $x^2$ terms in the Maclaurin polynomial and its factored form yields
$$-\frac{x^2}{3!} = -x^2\left(\frac{1}{\pi^2} + \frac{1}{4\pi^2} + \frac{1}{9\pi^2} + \cdots\right)$$
And multiplying both sides by $-\frac{pi^2}{x^2}$ gives us
$$\frac{\pi^2}{6} = 1 + \frac{1}{4} + \frac{1}{9} + \cdots$$
Comment: The modern objections to this argument should probably be mentioned. One cannot say "an infinite series is just like a polynomial" until convergence issues have been resolved. In this case, Taylor series arguments give us that $f_n(x) = \sum_{k=0}^n \frac{(-1)^k x^{2k}}{(2k+1)!}$ converges to $f(x) = \frac{\sin x}{x}$ as $n \to \infty$. But to use the argument above, one must justify that $g_n(x) = \prod_{k=1}^n 1 - \frac{x^2}{k^2 \pi^2}$ *also* converges to $f(x)$ as $n \to \infty$. One method would be to apply Weierstrass's factorization theorem (since $\frac{\sin z}{z}$ is holomorphic).
Comment: Right, the objections are valid, and though Euler's method of proof here was eventually vindicated, it should be noted that infinite series can't necessarily be treated in the same way as finite polynomials.
Answer: Yes. You are hereby awarded this Wikipedia article: http://en.wikipedia.org/wiki/Basel_problem.
Comment: You are hereby awarded a downvote for posting link-only answer.
Answer: This question Different methods to compute $\sum\limits_{k=1}^\infty \frac{1}{k^2}$ already contains proofs that does not rely   on Fourier series.
Also
Robin Chapman has a collection of proofs on his homepage.


What did Asimov think of Philip K. Dick?

Question: I'm finishing Asimov's 1981 compilation of essays, in which he offers numerous opinions on many authors, books, and TV shows. But it puzzles me that he makes no mention of Philip K. Dick, who by that time had already gotten big, and was in fact just one year from passing away. Asimov must have heard of him. Is there any published statement where Asimov says what he thinks of Dick?
Comment: Asimov thought he was a bit of a Dick.
Comment: Asimov included a Dick story in his [All Time Favourite Sci-Fi Stories](https://www.goodreads.com/book/show/459406.All_Time_Favorite_Science_Fiction_Stories_Vol_1) anthology
Answer: In 1986, Asimov wrote an introduction to Dick's story Impostor for Isaac Asimov Presents The Great SF Stories #15 (1953), and criticized him strongly for using drugs:

I never met Philip Dick, but I heard that, at least early in his career, he experimented with what some people call "mind-expanding" drugs. I found that distasteful.

In his autobiography I. Asimov (written in 1990, published in 1994), he referred to Dick as a "superstar of science fiction":

Even in science fiction, awards keep proliferating. There is the Hugo award (given in ever increasing categories) and the Nebula award. In addition, there are awards in the names of dead superstars of science fiction; awards named for John Campbell, Philip Dick, Ted Sturgeon, and so on. Perhaps in time to come there will be an Isaac Asimov award.
Comment: I don' read that as Asimov calling Philip Dick distasteful - I read it as Asimov finding his use of drugs distasteful. The later may well lead to the former, but they are not the same thing.
Comment: Calling someone "distasteful" was considered strongly criticizing them in the 80s? Must have been a different time.
Comment: Asimov uses his introduction to the story solely to make an attack on the general use drugs supposedly justified under the idea of being "mind expanding", which he strongly criticizes.  He doesn't really say anything at all about Dick or his story or writing, which is rather unfair of him, I think.  The only interview of Asimov I saw gave me the impression of an opinionated bore and this misuse of the introduction seems to reinforce that.  YMMV.  The anthology is on archive.org.


Azure Analysis Service Cube Sizes Changed Since July

Question: we have come across very strange thing the over all size and individual sizes of all AAS cube databases where reduced with out any changes happened. Did anyone saw this change dip and any cause?
Answer: it should have resolved now, Microsoft mentioned that was bug which hit most of the regions , we are on WEST US and MS released patch to make the size look accurate now
Answer: Yes! We've been having intermittent issues with this as well. Specifically what was happening was large spikes in memory usage. These spikes did not align with the timing of when our models were set to refresh but rather seems to have happened at random.
When models refreshed we would see an uptick in memory usage but it would fall after the model finished refreshing. That's normal. When we reached out to Microsoft their official response was "restart the service". We weren't thrilled with the response needless to say.
What we have done to combat this is use the Process: Clear command in-conjunction with our model refreshes. Since then we've only had a few of these incidents.
Comment: sirwinny, what tier you are using? and the intermittent spikes in memory is due to your end users activity if there are no scheduled refreshes, but there could be multiple other issues. And my issue described is different from what you are having. Since microsoft released 1500 support there are some changes happened at the way they calculate the size of cube. which i am not sure about.
Comment: @JayM We're using the S2 tier. At first glance it sounds like we're suffering from similar issues; I didn't elaborate very well. We not only had large spikes but also large dips. Your comment on end user activity I don't think applies here. Out models are small, 2gb is our largest model. We were seeing spikes and dips of 28GB+. We're also using compatibility 1400.
Comment: sure process clear will definitely help reducing the memory used by cube database in-memory, but it will cause data unavailability for users, but you can also check try checking the unwanted columns and hidden columns from aas and remove them, and if memory it self is a problem please vertipaq analyzer to check where is your memory and per table size by SELECT
DISTINCT
[CATALOG_NAME] as [Database],
[CUBE_NAME],
DIMENSION_CAPTION AS [Dimension],
DIMENSION_CARDINALITY AS [Count]
 FROM $system.MDSchema_Dimensions
ORDER BY CUBE_NAME  you need to change the default database name.


Send commands to another terminal

Question: I have this setup where I have computer with ssh and a display where I have a user logged in to terminal. What I want to do is send commands like I was using that local session with keyboard. I tried to echo to /dev/tty1 but it just shows what I typed instead executing it. Which makes sense. The system only has bash so no GUI or anything like that.
Comment: Do you really need to send commands to that session, or would executing them in an independent session (i.e. `ssh remotehost "some command; another command; yet another command"`) be sufficient?
Answer: The TIOCSTI ioctl can inject characters into a terminal, or see instead uinput on Linux to generate keyboard (or mouse!) input.

ttywrite.c - sample C implementation
Term::TtyWrite - Perl implementation
$ sudo perl -MTerm::TtyWrite \
  -e 'Term::TtyWrite->new("/dev/pts/2")->write("echo hi\n")'

Comment: This Q&A is Linux-specific, fortunately.  Note that other operating systems started to drop TIOCSTI a year after this answer was written.  https://unix.stackexchange.com/q/406690/5132

Send commands to another terminal


Can I search for Etched Champion with Enlightened Tutor?

Question: Can a creature in my library with protection from all colors, like Etched Champion be the target of my search spell Enlightened Tutor?
Answer: Yes, it can; for no less than three reasons:

Enlightened Tutor (like all other 'search your library' cards printed so far) does not target a specific card in your library, so protection doesn't play a role here.
Protection from X only functions when a permanent is on the battlefield. (Though players can have protection from X as well.)
Etched Champion's Metalcraft ability only works while it's on the battlefield, so it doesn't have protection to begin with.

(not 100% sure about the third one, actually)
Comment: It's worth noting that no card that searches libraries has ever targeted, generally when cards look at hidden zones they don't target, targeting really only refers to areas like the stack, grave and battlefield. Cards that go for the hand, deck or outside the game "choose"
Comment: #3 is true because metalcraft is a static ability, and static abilities create continuous effects while the permanent is on the battlefield (this is paraphrased). See rule 112.3d of comprehensive rules
Comment: Right, it would be physically impossible to choose a target in a hidden zone.
Comment: #2 and #3 are kinda the same; the text on a card generally applies only when it's on the battlefield, unless it specifically says otherwise (for instance, you can't activate a creature's activated abilities when it's in your hand, unless it's something like cycling that obviously only applies when it's in your hand).
Comment: Re "*generally when cards look at hidden zones they don't target, targeting really only refers to areas like the stack, grave and battlefield. Cards that go for the hand, deck or outside the game "choose"*", At least one exception: [Runic Repetition](https://scryfall.com/card/isd/72/runic-repetition)
Comment: @GendoIkari, Re "*it would be physically impossible to choose a target in a hidden zone*", That's not true. In fact, there's already a mechanic that requires keeping track of a card in a hidden zone.


Permissions : I don't need user informations

Question: I have just a quesition about facebook api.
I use this code to know if the user is logged on Facebook :
FB.init({appId: '**********', status: true, cookie: true, xfbml: false});

I don't ask permissions. But when I redirect the user with this script :
if (!response.session) top.location = "https://graph.facebook.com/oauth/authorize?client_id=********&redirect_uri=http://apps.facebook.com/my_apps/";

the user is redirect to the Permission Asking page...  But I don't need personnal informations in my application, I just need to verify if the user is logged on Facebook, and redirect it on login page. After he can use my application without permissions. maybe it's impossible... ?
Thanks you
Answer: You need to get the user's permission before you can get his login status. Search for login using facebook and use it.
Some facebook components like "Like Button" will have iFrame from facebook, So it can access user's facebook details.


Can anyone identify this Australian tree?

Question:
This tree is found in the Wrights Hill area on the New South Wales/Australian Capital Territory border.
Bark at breast height is curled and dense, becoming less dense at height.
Comment: Eucalyptus, but which one?
Comment: Welcome to Biology.SE. For tree identification we need close-up pictures of leaves and flowers — this is especially true for a large group like the eucalypts! Thank you for taking the [tour], you may also find it helpful to go through the [help] starting with [ask] questions effectively on this site. Thanks.
Answer: The changes in the bark makes it look like Eucalyptus melliodora (Yellow box).

Locations recorded are in this link. http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~melliodora
Some photos of this tree can be seen at:
http://www.nccma.vic.gov.au/sites/default/files/publications/nccma-41853_-_box-gum_grassy_woodland_identification_10-11_web_0.pdf


ultra stamina mode in Sony Xperia Z3+

Question: Can not turn off ultra stamina mode in my z3+
no application could be started
can not access the phone from the computer
help please
Answer: Ultra STAMINA mode extends battery lifetime significantly. You can use this mode when you know you won't be able to charge your device for a long time. Only a few basic functions, such as Phone and Messaging, are available
To deactivate Ultra STAMINA mode

Drag down the status bar to open the Notification panel.
Tap Deactivate Ultra STAMINA mode

ultra stamina mode in Sony Xperia Z3+


Expected Value of Nonnegative Identically Distributed Random Variables

Question: Let $X_1, X_2 \geq 0$ be two non-negative identically distributed random variables. I wonder if the following equation holds.
$$
\mathbb{E}[X_1X_2] = \mathbb{E}[Y^2]
$$
where $Y$ is a random variable having the common distribution of $\{X_1, X_2\}$.
My attempt: We know that, in general, $\mathbb{E}[X_1X_2] \neq \mathbb{E}[X_1^2]$ and/or $\mathbb{E}[X_1X_2] \neq \mathbb{E}[X_2^2]$. One can take $X_1 \in \{0,1\}$ with probability $1/2$ and take $X_2 := -X_1$. However, the nonnegativity excludes this case.
Also, if we look at
$$
\mathbb{E}[Y^2] = \int y^2\, dF_{Y} = \int y^2 \, dF_{X_1,X_2}
$$
where the last equality hold since $Y$ has the common joint distribution of $\{X_1,X_2\}$. But I get stuck to see if this is equal to $
\mathbb{E}[X_1X_2] = \int x_1x_2 \,dF_{X_1,X_2}$. Any comment is appreciated.
Comment: What if $X_1$ and $X_2$ are independent?
Answer: It is easy to find such examples. If $EX_1X_2=EX_1^{2} (=EX_2^{2})$ then $E(X_1-X_2)^{2}=EX_1^{2}+EX_2^{2}-2EX_1X_2=0$ so $X_1=X_2$ a.s..  Can you come up with two non-negative r.v.'s with the same distribution (say $exp(1)$)  which are not a.s. equal?


Dynamic Populated Drop Down List PHP MySQL

Question: I have two Drop Down Lists, the second ones are based off which one the users selects in the first drop down. I was going to use Javascript to dynamically change the second drop down. But now here comes the problem. This information is going to be stored on a user's profile. So ideally I would like to be able to pull this information out of MySQL database and display it on a PHP page. How would I go about loading the proper dynamic menu when I populate the list from MySQl. How can I accomplish this the way I want. I dont think javascript would work in this case would it?
Answer: If you don't want a page refresh, then the answer is "JavaScript". Now, you have a couple of options there. Personally, I prefer to load more up front, so I keep a JSON object which outlines the possibilities and then I swap static content for static content.
This would mean that onchange I would have something like:
<code>var first = document.getElementById( "id of first select" )
var items = possibilities[
    first.value // you can also do things with selectedIndex and options if needs.
];

var second = document.getElementById( "id of second select" )
for( var i in items )
{
    var opt = document.createElement('option');
    opt.setAttribute('value', items[ it ] );
    second.appendChild( opt );
}
</code>
Your other option is to send data "over the wire" and get it working through AJAX. Not having room for a tutorial, I think I can safely link you to this one.
Answer: You certainly can do this with JavaScript.  It is called AJAX.  Most people will use a JavaScript framework like jQuery to abstract out some of the issues with using the XMLHTTPRequest object to establish a connection with your server and request/receive data.
You still work out the server side code in PHP and MySQL, you just use AJAX to call on the data and work with it.


How intercept the "Cancel" and "OK" actions belonging to the native IOS picker component?

Question: I have a question about the Picker component in Codename One. How can I intercept the "Cancel" and "OK" actions belonging to the native IOS picker component? In my UI specifications, I need to differentiate this two events since that the "OK" button validates the form, and the "Cancel" button closes the form. thank you for your help.
Answer: I believe you could subclass it and override the showDialog method. Dialogs usually return a boolean value, so you could store that in a local variable and then when the dialog is disposed take whatever action is needed.
Comment: Thanks for the information but it seems that Dialog is not used in the case of nativePicker. Any other ideas would be welcome ;)
Answer: You can't as some OS's don't have them. This is specific for Android.
Generally if the picker value changes revalidate if it didn't change don't.
The underlying Display picker API includes this to some degree as it will return null for canceled operations.
Comment: Thanks Shai for this clarification


C# Float vs. VB.net Single - Namin' complainin'

Question: Why is it called a single in VB.net?  I'm sure there is a good reason but it doesn't seem intuitive to a non formally trained programmer like me.
Answer: BPAndrew's question seems to be really "why float in C# and Single in VB.NET", which noone actually answered, so here's my 2p...
The use of "float" in C# seems to be a throwback to its C/C++ heritage. "float" still maps to the System.Single type in C#, so the keyword just exists for convenience. You could just as well declare the variable as "Single" in C# the same as you do in VB.NET.
(And as stated above, naming them Single/Double actually makes more sense as they are single/double precision floating-point numbers.)
Comment: `double` is another keyword in C# that exits for convenience that maps to `System.Double`.
Comment: 2p, that's pretty costly, compared to the CDN penny.
Answer: As others have said, they map to "single" and "double" precision binary floating point types. Personally I think it was a sideways step to just name System.Single and System.Double - why not System.Float32 and System.Float64 to match the integer types?
Comment: Also, the [CIL](http://en.wikipedia.org/wiki/Common_Intermediate_Language) calls them `float32` and `float64`, respectively, corresponding exactly to the `System.Single` and `System.Double` of the [BCL](http://en.wikipedia.org/wiki/Base_Class_Library).
Answer: The reason is that both single and double are both Floating Point numbers.
single is short for Single Precision Floating Point Number (32 bits)
double is short for Double Precision Floating Point Number (64 bits)
Therefore to call a floating point number float is ambiguous.
http://en.wikipedia.org/wiki/Single_precision
http://en.wikipedia.org/wiki/Double_precision
Answer: I think it is a shorthand for "Single-precision" Double is "Double-precision"
While C-style int and float was probably referring to "integer" and "floating point"
Comment: int means integer, which is wholly different than a fixed-point (decimal) number. fixed-point is exactly that, a real number with a pre-set (fixed) precision. http://mathforum.org/dr.math/faq/faq.integers.html
Answer: I would like to add my hypothesis for the naming convention.
In the C/C++ word that Java and then C# were born out of, int/long and float/double could vary based on the architecture in which it resides, 32-bit or 64-bit.
In portable VM languages like Java and C#, these types do NOT change, and therefore, the naming convention could reflect that. Or it could just be what's most comfortable the last generation of programmers. Or we could create aliases for everything and let everyone do whatever they want!!
Answer: The technical name is a 'single precision floating point', 'single' because it takes a single word in memory (32 bits). A double, meanwhile, takes 64 bits on most architectures.
Comment: Originally the single didn't mean single word, since they were 16 bit machines. Floating point and its precision has been around longer than 32 bit machines have.


nxlog get logs from applications and services logs

Question: i am having issues getting data of an event log , located on   the applications and services Logs. I have put a query in the nxlog conf file that get the erros,warning,critical logs from the application event log but it doesnt work.
Any help would be appreciated
I am trying to get the Stream event file in application and service logs see following screenshot
 screen_shot
Here is my nxlog conf for the input
<Input eventlog>
 Module      im_msvistalog
Query   <QueryList>\ <Query Id="0" Path="Application">\ <Select Path="Application">*[System[(Level=1  or Level=2 or Level=3)]]</Select> </Query>\ </QueryList>
 </Input>

thanks
Answer: You should check nxlog.log for any errors.
To me it looks like the Query line is incorrect as there should be a linebreak after each \.
Comment: i went to check the nxlog.log and it says that  the query is malfunctioned.No idea why


Dirac vs KG propagation amplitude

Question: Can someone explain to me the physical meaning of $\bar{\psi}=\psi^\dagger\gamma^0$ in the Dirac equation? I understand it is obtained as one of the solutions of Dirac equation and it is used to build the scalar $\bar{\psi}\psi$ but I am not sure I understand its physical meaning. I see that when we calculate propagation amplitudes we use $<0|\psi(x)\bar{\psi(y)}|0>$ and not $<0|\psi(x)\psi(y)|0>$ (as we would do in Klein-Gordon equation), so I guess from this that $\bar{\psi(x)}$ applied on the vacuum state creates a particle at position x, but $\psi(x)$ does exactly the same thing (and I mean both create a particle, not antiparticle) so what is the point of that, then?
Answer: The Dirac adjoint is defined in order to construct a Lorentz scalar, as $\psi^\dagger \psi$ does not transform as a scalar unless the representation were unitary, which it is not.
When we quantise the theory and expand the fields in terms of operators, we have schematically,
$$\psi \sim b + c^\dagger, \quad \psi^\dagger \sim b^\dagger + c$$
ignoring the integration and other factors. This means that $\psi$ containing $c^\dagger$ creates particles so to speak with the spinor $v(p)$ corresponding to negative frequency solutions and $b^\dagger$ in $\psi^\dagger$ contributes positive frequency solutions $u(p)$ of the Dirac equation.
Comment: Thank you for your answer. I kinda got this part. The main thing I don't understand is why do they define the propagation of a particle from y to x in that way, and not as they do in KG case?

Dirac vs KG propagation amplitude


Order of Talmud Torah for a baal teshuvah

Question: What's the Halacha for the order of what Torah study a baal teshuvah should do? If a Jew has little to no Talmud Torah background and they become religious in life, what should they prioritize learning? Tanakh, Mishnah, Talmud, commentaries, Halacha, etc.?
Comment: I would assume practical halacha would be the first priority so such a person would know how what to do. That and also something that keeps them engaged in their yiddishkeit weather that be chassidus, mussar, or something that is inspiring in general. This would cover what to do, not do, how to do it, and why
Comment: Not directly an answer, but Rav Moshe Shternbuch (Teshuvos VeHanhagos, Vol. 1, p. 241, Siman 350 Orach Chaim) writes that just like with a baby, there are small steps, so too with a baal teshuvah, nothing should be forced and too much at once. Take it easy, and don't do too much at once. [here](https://hebrewbooks.org/pdfpager.aspx?req=20025&st=&pgnum=245).
Comment: There is no set order. Speak to a rabbi to see what makes sense for you.
Answer: This is going to be quite dependent on the personality and level of the baal teshuva (some of them are quite learned even if they only start to practice now, others have little or no knowledge). The following is my personal opinion based on my own situation (30 years ago) as well as learning with a number of baalei tshuva over time, some of them for years.
Overall I believe one needs to balance the practicality of halacha (required to practice properly) with enough inspiration and fundamental knowledge to show the rationality of halacha. Thus, I would learn along two parallel tracks.
Halacha

Laws of daily living, starting with a broad overview of all laws (e.g., using Kitzur Shulchan Aruch, or better R Zeev Greenwald's Laws of Daily Living (Shaarei Halachah) or R Aharon E. Marcus's Halacha 24/7/12
Then moving to laws of Shabbat, holidays, kashrut, family purity, etc.
There are also very good overviews of overviews which might be useful, e.g., R Berel Wein's Living Jewish, R Mordechai Katz's Understanding Judaism

Fundamental content

Starting with the parasha of the week (e.g., using the Stone or Steinsaltz Chumash) and any commentary you like in addition (e.g., R Sacks for someone more intellectual)
Musar or hasidut (e.g., Ramchal's Mesilat Yesharim or Derech Emuna, or simplified versions such as R Ben Tzion Shafier's Stop Surviving, Start Living: The Shmuz on Life
Whatever else will be interesting for that particular individual, e.g., Jewish history e.g., R Ken Spiro (Aish HaTorah)'s Crash course in Jewish history or philosophy

Getting familiar with Hebrew reading and learning prayers in parallel is also obviously key.


Presentation of $\pi_1$ of compact orientable surface by induction?

Question: I need to prove by induction $\pi_1(\Sigma_g)= \left\langle a_1,b_1,\dots ,a_g,b_g\mid \prod_i [a_i,b_i] \right\rangle$. For genus 1 this holds since $\pi_1(T^2)\cong \mathbb Z\times \mathbb Z$. For the general case I thought of using the connected sum formula
$$\pi_1(\Sigma_g)\cong \pi_1(\Sigma_{g-1} \# T^2)\cong \pi_1 (\Sigma_{g-1}\setminus D)\amalg_\mathbb{Z}\pi_1(T^2\setminus D)$$
but I'm kind of lost now. I thin $\pi_1(T^2\setminus D)\cong \mathbb Z\ast \mathbb Z$ since its a bouquet of 2 spheres, but I don't know how to proceed...
Comment: A way to proceed is the following: As a first step, proof by induction that for a surface $\Sigma_{g}^{1}$ of genus $g$ with one boundary circle, and a point $x$ on the boundary, the fundamental group is a free group $\pi_1(\Sigma_{g}^{1},x) = \langle a_1, b_1, \ldots, a_{g}, b_{g} \rangle$, where the boundary circle maps to the element $\prod_{i} [a_i,b_i]$. In this case, the induction step is a direct application of the Seifert-van-Kampen theorem.
Comment: @Anubhav.K doesn't the polygonal representation circumvents induction?
Comment: Do you know the polygonal representation of $\sum_g$?
Comment: @OlesWohnzimmer can you post this as an answer, with some details?
Comment: @OlesWohnzimmer how do you see the boundary circle maps to the product of the commutators?
Answer: Let $\Sigma_{g}^{1}$ be denote a surface of genus $g$ with one boundary circle. Let $\iota_g\colon \textrm{S}^{1} \to \partial\Sigma_{g}^{1}$ be a homeomorphism on the boundary. For convenience later on, we write $\textrm{S}^{1} = [0,1]/\{0 \sim 1\}$, and we fix base points $x_g = \iota_g(0) \in \Sigma_{g}^{1}$.
I assume that the following statement is known:

$\pi_1(\Sigma_{1}^{1},x_1)$ is a free group, and if $a_1$ and $b_1$ denote the homotopy classes of the longitude and the latitude circle starting at $x_1$, one has $\pi_1(\Sigma_{1}^{1},x_1) = \langle a_1,b_1 \rangle$. In this notation, the boundary $\iota_1 \colon \textrm{S}^{1} \to \partial \Sigma_{1}^{1}$ represents the class $[a_1,b_1] = a_1 b_1 a_1^{-1} b_1^{-1}$.

One can prove this statement by constructing $\Sigma_{1}^{1}$ as a quotient of a square with a disc removed (e.g. $[-2,2]^{2} \setminus \{x \in \mathbb{R}^{2} \mid ||x||< 1\}$) with opposite edges identified.
Now one can inductively construct $\Sigma_{g}^{1}$:

Consider the intervals $\iota_1([0,\frac{1}{2}])$
  , $\iota_{g}([0,\frac{1}{2}])$ in the boundaries of $\Sigma_{1}^{1}$ and $\Sigma_{g}^{1}$. Identifying these intervals yields a homeomorphism:
  $$ \phi_{g} \colon \Sigma_{1}^{1} \cup_{[0,\frac{1}{2}]} \Sigma_{g}^{1} \,\tilde{\to}\, \Sigma_{g+1}^{1}, \quad \phi_g(x_1) = \phi_g(x_g) = x_{g+1}$$

Now the intersection of the subspaces $\phi_{g}(\Sigma_{1}^{1})$ and $\phi_{g}(\Sigma_{g}^{1})$ in $\Sigma_{g+1}^{1}$ is an interval, hence contractible. The Seifert-van-Kampen theorem then computes
$$ \pi_1(\Sigma_{g+1}^{1},x_{g+1}) \,\tilde{=}\ \pi_1(\Sigma_{1}^{1},x_1) \,\ast\, \pi_1(\Sigma_{g}^{1},x_g) \,\tilde{=} \, \langle a_1,b_1,\ldots,a_{g+1}, b_{g+1} \rangle,$$
where the indices of the generators of $\pi_1(\Sigma_{g}^{1},x_g)$ were shifted by $1$ to avoid conflicting notation. The new boundary circle is homotopic to the concatenation of the two old boundary circle, hence:
$$[ \iota_{g+1} ] = [\iota_1] \cdot [\iota_{g}] = [a_1,b_1] \cdot \prod_{i=1}^{g} [ a_{i+1}, b_{i+1}] = \prod_{i=1}^{g+1} [ a_{i}, b_{i}] \in \pi_1(\Sigma_{g+1}^{1},x_{g+1})$$.
As a last step, one constructs $\Sigma_{g}$ by gluing a disk to $\Sigma_{g}^{1}$ at the boundary circle. Another application of the Seifert-van-Kampen theorem yields the desired result:
$$ \pi_1(\Sigma_{g},x_g) = \langle a_1,b_1,\ldots, a_g,b_g\mid \prod_{i = }^{g} [a_i,b_i] \rangle$$


Distribution of a sum of a product of Bernoulli vectors divided by the sum of the first Bernoulli vector

Question: I'm trying to understand the distribution of a normalized sum of a product of Bernoulli random variables. Specifically, I have two vectors $M_1$ and $M_2$ of length n. Each element of each vector is a Bernoulli random variable with varying success probability $p_i$. We can assume for now that each element is independent from all other elements and the vectors are independent from each other. With this assumption the sum of elements of vector $M_1$ is $\sum_i M_{1i}$ and follows a Poisson binomial distribution with expected value $\sum_i p_{1i}$. The element-wise product of both vectors $M_1 M_2$ consists again of Bernoulli random variables, this time with success probabilities $p_{1i}p_{2i}$ for each element. The sum of this vector of products $\sum_i M_{1i}M_{2i}$ (which is also the inner product of the two vectors) is then again distributed with a Poisson binomial distribution with expected value $\sum_i p_{1i}p_{2i}$.
What I am interested in now is the distribution of $Z=\frac{\sum_i M_{1i}M_{2i}}{\sum_i M_{1i}}$. Basically this is the number of common successes between the two vectors divided by the number of successes in the first vector. This problem seems simple enough to possibly have a closed-form expression, but I don't know what to look for. Assumptions of n being large are acceptable, but exact solutions are preferred. Any pointers to either a solution or a problem of a similar form in an application would be greatly appreciated.
Comment: If by "closed-form" you mean an expression that asymptotically in $n$ is $o(n)$ in length, you will necessarily be disappointed because it depends (at a minimum) on all the $p_{2i}$ separately. Approximations can be developed by making assumptions about the average relationships among the $p_{i1}$ and $p_{2i},$ so if you have such information, please share it.
Comment: thank you for the clarification. I'm fine if the expression depends on all the p_{2i}, especially if like in the Poisson Binomial Distribution it would result in a straightforward expected value and variance. Even better of course would be if it converges to a well-known distribution. On the average relationship between p_{1i} and p_{2i} : I don't think there is anything else but to say that they are conditionally independent from each other. But would specifying P(p_{2i}|p_{1i}) be helpful? I might be able to make an assumption based on what my data shows
Comment: Convergence results likely depend on details of what happens to the $p_{ji}$ as $i$ grows large.
Comment: p_{ji} would not change in distribution as i gets large, in the sense of probabilities becoming smaller or larger, if that's what you mean.
Comment: Are you supposing these values are themselves random variables?  If so, that would be useful information to include -- along with any assumptions about those distributions.
Comment: The p_{ji} are themselves derived from another random variable, and are basically portraying the chance that that random variable crosses a certain threshold (in this case 1). Sadly, I can't make a good assumption about the distribution of those underlying random variables. Not a priori, and in the data they look all over the place as well. But one could consider the p_{ji} as a random variable. Could you briefly sketch why that would help?
Comment: It could help by providing a simple, parsimonious asymptotic characterization of the $p_{ji}$ in terms of parameters of a family of possible distributions.  That's a huge improvement over assuming nothing at all about them and creates the possibility of a closed-form approximate solution.
Answer: Here is my attempt at the distribution; more elegant/compact solutions quite possibly exist however.
Let $A:=\sum_i M_{1i}$ and $B:=\sum_i M_{1i}M_{2i}$. Also, suppose for some given $A$, let $M_1^{A,k}$ correspond to a specific $M_1$ vector whose sum is $A$. So, there are ${n\choose A}$ different $M_1^{A,k}$ vectors for a given value of $A$.
The joint PMF $P(A=a,B=b)$ where $b\leq a\leq n$ is
\begin{align*}
P(A,B) &= P(A)P(B|A)\\
&= P(A)\sum_kP(B|M_1^{A,k})P(M_1^{A,k}|A)\\
&= \sum_kP(B|M_1^{A,k})P(M_1^{A,k})
\end{align*}
Now, $P(B|M_1^{A,k})$ is a Poisson-binominal PMF. Specifically, suppose $\{j\}$ is the set of indices of the "successful" components of $M_1^{A,k}$. We then look at $M_2$ and focus on its $j$ components as well; $P(B|M_1^{A,k})$ is simply the probability that $B$ of those $M_{2j}$ components are successful.
Now, we look at $P(M_1^{A,k})$, which is simply the probability of having the $j$ components be the successful ones, ie $P(M_1^{A,k})=\prod_{i\in\{j\}}p_{1i}\cdot \prod_{i\not\in\{j\}}(1-p_{1i})$
Now that we have expressions for our summands in the joint PMF $P(A,B)$, we turn to $Z=\frac{B}{A}$. Clearly $Z$ is discrete and rational-valued. Its PMF will be
$$P(Z=z)=\sum_{(a,b)\;st.\;b/a=z,\; b\leq a\leq n }P(A=a,B=b)$$
Technically that's it, and it's "closed-form" given all the sums/products are finite. But it's ugly sorry!
Comment: Thank you for your answer, this is really helpful with notation and with the conditional probability idea, will +1 once I have enough reputation. I won't accept it yet hoping that someone will come up with a smart assumption that can lead to a nice closed-form solution or at least approximation. Could you think of a similar problem to this which does have a known distribution as the solution? Maybe I could take some inspiration from there
Comment: @NilsR I imagine things will simply greatly if further assumptions or restrictions are placed on the $p_{ji}$ values; otherwise, I fail to see how we can avoid long sums or products. The other thing of course is that $Z$ is rational, so its PMF will likely exihibit lots of "unsmoothness", which is not conducive to the existence of a compact PMF (which is likely to be continuous if extended to the reals).


How to distinguish between \r\n and \n in VIM

Question: In VIM I can show all the hidden characters in a file via the command ":set invlist". However, end of line sequences are always displayed as $ whether it is a carriage return/line feed or just a line feed. How do I distinguish between the two types of line endings?
Answer: I know this is an older question, but I needed a similar answer and was able to find something a little better.
:set ff?
This will tell you what type of file vim thought it was when it loaded. Of course you have to have vim configured to recognize the line endings of the particular file.
More details about VIM File Formats Blog Post.
Answer: refer to VIM change end-of-line format.
If you set the file to unix mode then the carriage return shows up as ^M and the linefeed displays as the end-of-line character.
Comment: I always fix to the unixmode and usually run `dos2unix` on text files from Windows.
Comment: I did this, and it converts the file format in silently. However, I can test the line ending of the file effectively but awkwardly by setting one format and quitting then setting to the other format and quitting. Whichever sequence leads to a "you have unsaved changes" message is the format the line endings are not in.
Comment: Best answer at the moment, but I'll change the accepted answer if anyone comes up with a better one.


Adding quick link on admin home page (Prestashop 1.5.4)

Question: Good day! Tell me, how can I add a quick link on the home page of the administrator to configure my module?
Answer: Follow the following steps:
1) In admin section to go Administration at top menu and then click on Quick Access.
2) IN next page click on Add new and you will see a form
3) Now open admin panel in another tab and to the module page or section, of which you want to place a link in quick access.
4) Copy that complete link in note pad and remove the token section of the link. It is required to remove the token section according to Prestashop.
5) Now come back to the add new form for quick access, give your link a name and then copy that modified link to the Url field.
6) Save it and you will have that link in quick access.
The above is method is used to add it at admin. Now if you want to add it pro-grammatically you can follow the following steps.
1) In your module in the install function, user a code like below
<code>Db::getInstance()->insert('quick_access', array('new_window' => 0, 'link' => 'link_to_your_module_page'));

//an entry is made in quick_access table, get the quick_access id to insert lang data

$id = Db::getInstance()->Insert_ID(); //this will give you last inserted ID from quick_access table which is your current quick_access id.

//now make insertions in quick_access_lang table for multi language data.
//get all your site languages, and place a foreach loop and in that loop insert
//data into the quick_access_lang table using below code

Db::getInstance()->insert('quick_access_lang', array('id_quick_access' => $id, 'id_lang' => 'lang_id', 'name' => 'name of your link'));

//Now for uninstalling module, you want to delete the link, so you need to store the quick access link id in configuration table so you can use it later.

Configuration::updateValue('MY_QUICK_ACCESS_LINK_ID', $id);
</code>
2) Now in your uninstall function in your module class, place the below code
<code>$id = Configuration::get('MY_QUICK_ACCESS_LINK_ID'); //get id of your quick access link
Db::getInstance()->delete('quick_access', 'where id_quick_access = '.$id);
Db::getInstance()->delete('quick_access_lang', 'where id_quick_access = '.$id);

 //now delete the id from config table
Configuration::deleteByName('MY_QUICK_ACCESS_LINK_ID');
</code>
Note : The above code is not tested, it may / may not need some adjustments.
Thank you
Comment: Thanks! But I want to add a quick link using php when installing the module, and when you remove my module and also delete a quick link on the home page of the administrator. You can send the sample code for file **/override/classes/controller/AdminController.php**?
Comment: Check my updated answer now. I updated to give you idea and sample codes how to do it. Thanks
Answer: There is a hook in Prestashop DisplayAdminHomeQuickLinks it will help you to add quick link on prestashop admin panel. I have use this in my theme. http://goo.gl/0S3mn And it will help you to solve the quick link.
Answer: In Prestashop 1.6.1 (maybe earlier too) in Admin view, at the top of the page, Quick Access has the option to "Add current page to QuickAccess". So just navigate to the Configuration page you need and use it.


How do you embed a form within a form for infopath 2013

Question: I need to embed a child form into a parent form within infopath 2013. Does anyone know how to do this??
Answer: This is not supported (as you cannot embed  tag inside and  tag. Not sure what is your use case but I assume you need to update another list. If you are on prem you could use code behind to update another list using custom code.


How to remove a ticks on my dog?

Question: My dog have many ticks, and I don´t know how I can help him. He took gardenal bath and didn´t worke, and also led injection!
Answer: Tweezers, and patience. Pluck the little buggers off by the head as detailed here. I'd recommend reading the whole thing; it's got a lot of useful do's and don't's for dealing with ticks. Just make sure it's the head you grab and not the body, otherwise the head with stay in your dog and release toxins when it dies.

How to remove a ticks on my dog?


Gravity and antimatter

Question: If we put earth like planet made up of antimatter (same mass of earth, same diameter etc..)  with same distance from moon as current distance between earth and moon  then center of gravity of moon and earth will change or not? Why?
Comment: Related: http://physics.stackexchange.com/q/9371/2451 and links therein.
Answer: In short, answer is no. Gravity center won't change. For example imagine electron and positron. After measuring I will get that Mass of electron and positron are same: $9.10938291 × 10^{-31}$ $kg$. So electron and positron have same mass but different charges (Charge of electron is $-1.60217657 × 10^{-19}$ $coulombs$ and charge of positron is $1.60217657 × 10^{-19}$ $coulombs$). Charges have no effect on gravity center. And if mass is same why should gravity center change. (Gravitational Force depends on mass (and radius) $F=G\frac{Mm}{r^2}$)
Here's image of Hydrogen and Anti-Hydrogen atom (Only Charges are different not masses).

So in conclusion Anti-Earth and Anti-Moon will have same gravity center as normal Earth and Moon.
EDIT: Center of gravity of earth and moon is:

But if we will add Anti-Earth at same distance from moon as earth it will look like this:

And Center of gravity of this system will be at moon (Because Anti-Earth have same mass (Particle and its Anti-Particle have same mass), radius and distance from moon as Earth. But it will be Until Earth will meet Anti-Earth and they will annihilate).
(Sorry for my very poor drawing)
Comment: That what I don't ask ... I write my question in different word: If we have three entity 1)earth 2) moon 3) anti-earth and anti earth has same mass and same diameter as earth( means anti earth is carbon copy of earth except that it is made of anti material). Now what I am trying to say is if at first anti earth is not present and we measure center of gravity between earth and moon and now we add anti earth in this scenario. Moon is same distance from both earth and anti earth now then center of gravity will now change or not?
Comment: @user43004 so you mean that if earth and anti-earth are rotating around each other and moon is between them?
Comment: Yes that what i mean now what will be scenario?
Comment: @user43004 I have edited my answer (I have added  results of that scenario in my answer)

Gravity and antimatter


Best practices for syncing two Macs using Sierra

Question: I have three children who share two desktop Macs.  Each kid has her own account on each computer, but up to now none of them has had an Apple ID (they do not have phones or mobile devices, although they do have old-school digital cameras).  Until recently the computers were both running Mountain Lion, and keeping each kid's personal files and photos in sync between the two machines was an ongoing headache involving USB thumb drives and lots of manual copying.
So I've decided to take the plunge and upgrade both machines to Sierra, create Apple IDs for each kid, and use iCloud to sync their Desktops, Documents, and Photos.  This seemed like the simplest way to make sure that each kid's account on each computer would automatically stay in sync with the corresponding account on the other computer.
I'm wondering if people with experience with this setup (or a similar one) can share any best practices with me before I go all-in on this.  For example:

Am I correct that this setup will work as intended?
Will syncing of one user continue to run in the background if a second user logs in to the same machine?  (Presumably not if the 1st user logs out, but what if they stay logged in while the second account becomes active?)
If I link all the accounts on both computers to iCloud, will I end up with duplicate copies of files that currently reside on both machines?  Or will the syncing process recognize when two files are copies of one another?
Would it be better to upgrade one machine, link all of the accounts on that machine to iCloud, then do a clean install on the second machine and create & sync new accounts on that machine to iCloud?
If I notice that files don't seem to be syncing automatically is there a way to force a sync?
Answer: I am going to try answering per question, except the first two. So here goes my 5p:

Am I correct that this setup will work as intended?
Will syncing of one user continue to run in the background if a second user logs in to the same machine? (Presumably not if the 1st
  user logs out, but what if they stay logged in while the second
  account becomes active?)

Yes, for both.
Also in addition, for best practices and keep each user's file separate, create the Documents, Pictures, etc folders inside and iCloud Drive. Now ask each child to put all their stuff in that folder.
If did not do that, it will still be stored inside the local machines' ~/Users/ folder.

If I link all the accounts on both computers to iCloud, will I end up with duplicate copies of files that currently reside on both machines? Or will the syncing process recognize when two files are copies of one another?

Do you mean using the Auto upload feature?

Would it be better to upgrade one machine, link all of the accounts on that machine to iCloud, then do a clean install on the second machine and create & sync new accounts on that machine to iCloud?

If you are moving all of User1's docs to their iCloud Drive, it does not matter.

If I notice that files don't seem to be syncing automatically is there
  a way to force a sync?

Not that I know of


iPod Touch 1st Gen songs stuck on repeat

Question: My iPod touch (1st gen) is stuck on repeat. I can't figure out how to turn off the repeat function. All i see is the shuffle option in the songs section.
Answer: So I stumbled upon a solution. I clicked on "Now Playing" After which I clicked on the "Play" button to start the song. Staying in portrait mode I touched the screen once (where the default song icon is) and the song time along with the shuffle and repeat option slid down. I was able to turn off repeat from there by clicking on the "repeat" option (it turned from blue to white color")


Projective Resolution and Homology

Question: Let $A$ be an abelian category with enough projectives. We construct a projective resolution of an object C as follows: since $A$ has enough projectives we have an epimorphism from a projective object $P^0$ onto C. Let $ΩΑ$ denote its kernel. Given $ΩΑ^{i}$ take an epimorphism $P^i$-->$ΩΑ^{i}$ and let $ΩΑ^{i+1}$ denote its kernel. Concaneting these short exact sequences together we obtain a projective resolution of C. I am having trouble to understand why the "glued" sequence is exact at every position.
Comment: Sure! A sequence A-->B-->C is exact at B if gof=0 and Imf is isomorphic with Kerg. In category theory, kernel of a morphism f:X-->Y is defined to be the pull back of a certain diagram, which is an object with a universal property as you noted.
Answer: As you say, given $A\in\text{Ob}(\mathcal{A})$, where $\mathcal{A}$ is an abelian category with enough projectives, you construct a resolution of $A$ by considering short exact sequences of the form
$$0 \to \Omega^{i+1}(A)\to P^{i}\to \Omega^{i}(A)\to 0,$$
where $P^{i}$ is projective and $\Omega^{0}(A)=A$, and gluing them together:
the map $\phi^{i}:P^{i}\to P^{i-1}$ is the composition
$$P^{i}\to \Omega^{i}(A)\to P^{i-1}.$$
The kernel of this map is $\Omega^{i+1}(A)$ and the image is $\Omega^{i}(A)$ by construction.
Therefore if you have the sequence
$$P^{i+1}\xrightarrow{\phi^{i+1}}P^{i}\xrightarrow{\phi^{i}} P^{I}$$
you have $\text{im}(\phi^{i+1}) = \Omega^{i+1}(A)$ and $\text{ker}(\phi^{i})=\Omega^{i+1}(A)$, so the sequence is exact. In particular, the resolution is exact at each point.

Projective Resolution and Homology


What weapon combinations keep my biotic cooldowns at 200%?

Question: I'm heavily oriented toward biotic usage, so my current loadout consists of only my pistol and SMG.  There are some occurrences, though, where I wish I had my sniper rifle or shotgun with me.  Factoring in all the available weight reduction mods and all classes' weight capacities, what combinations allow me to keep biotic cooldowns at 200%?
Comment: You should specify your class, different classes have different weight capacity.
Comment: @kotekzot I was hoping for an answer that covers all the classes as well, so each class doesn't require a separate question.  I'm playing an engineer, though
Comment: Ah, I assumed "my" referred to a specific character.
Comment: fyi I haven't forgotten to update my answer yet, I plan to eventually put out a detailed answer involving base level weapons, level 5 weapons, and level 10 weapons
Comment: @yx. I didn't doubt it, I was just going through my unaccepted questions.  Thanks!
Comment: I haven't found any better weapon combinations with level 5 weapons, its taking me a while to get to level 10 weapons since I'm mostly playing multiplayer these days
Answer: So far, with my vanguard, the best loadout I can carry is this combination:

M-3 Predator V pistol
M-4 Shuriken V with -60% weight mod
M-15 Vindicator V

This combination keeps my recharge speed maxed at 200%.  This is with the +35 weight capacity upgrade taken at Rank 5 Assault Mastery.
If I swap out the Predator for a M-77 Paladin V then my recharge speed drops to 196%
I might be able to improve this in a New Game+ by upgrading the weapons even further, but on my current run this seems to be the best I can do.
Combination #2 if you prefer sniper rifles:

M-97 Viper V (for more damage, M-92 Mantis V gets you 189% recharge)
M-4 Shuriken V with -60% weight mod

I'll keep you updated if I find lighter weapons.
Answer: Best load out for Vanguard weapon wise if your going biotic are:
-Disiple Shotgun leveled to the max, with Shreeder, and melee upgrade.
-Paladin Pistol with barrel, and pierce mod.
-Tempest SMG with lightweight, and mag upgrade.
If your Assualt Mastery is maxed out with weigh capacity selected you will be at 200% biotic efficiency with these three weapons.
Best armor to use is the Terminus Armor since it ups your shields, Melee strengh, and ammo capacity, all are huge for a biotic charge happy vanguard.
*leveled to the max does not ultimitely mean level 10 I've leveled to 5 and still was at 200% biotic ability.


How are the TensorFlow models, outputting image-feature vectors, trained?

Question: There are pre-trained models outputting Image Feature Vectors like https://tfhub.dev/google/imagenet/efficientnet_v2_imagenet21k_ft1k_s/feature_vector/2. While from the name one can deduce the architecture (EfficientNetV2) and the training data set (ImageNet-21K), I'm interested in how the training process was done. Was it trained "classically" for classification with some dense layers at the end that were chopped off after training? Or was some other technique like triplet loss applied?
Answer: This is described on the model page:

This model contains a trained instance of the network, packaged to get feature vectors from images. If you want the full model including the classification it was originally trained for, use google/imagenet/efficientnet_v2_imagenet21k_ft1k_s/classification/2 instead.

So the original model was trained for classification and then the last projection (the one projecting into the logits) was removed to create the image feature vector version.
Answer: I would exclude any triplet or margin loss simply because they are too specific for metric and similarity learning among classes of entities: for example the triplet loss was designed for face recognition, so to measure the "distance" of two images, which is required to be low if these belong to the same identity.
These image feature vectors models should be generally applicable to whatever downstream task (taking into account a possible fine-tuning), so, I'd say that these models are either: 1) trained with the method suggested by their own paper, 2) by also making use of modern practices, or even 3) by means of some self-supervised method so that to boost the representational power of the learned image vectors.


Remote administration methods

Question: There is a requirement for users to remotely access one of my corporate servers from internet. Policy wise, i would want them to at least use 2FA for communication,eg VPN Tokens, password+SMS etc. However, i also recognized that some users may not have the budget to implement at least 2FA. Hence, would like to gather feedback from people in the industry, what could be a good enough alternative to 2FA that could also adequately enable similar type of protection for remote access.
thanks
Answer: The good news is two-factor can be free.  Google authenticator is free and mixed with FreeRadius should work with just about any access device.
It is not as fancy or secure as RSA's or some of the others but it is pretty simple to implement and does satisfy a second factor to username and password.
From what I can tell it looks to be certificate based since it does not need a server to talk to on the authentication side, just accurate time.  It does not have the extra protection of RSA for guessing OTP's or pin's but some of that can be accomplished with intruder detection on the device utilizing the authentication.
One thing to watch for, if your using your phone to access the servers and to access the OTP for GA, I do not believe it is considered a 2nd factor from a NIST perspective, as the thing you have should be separate from the device you login from unless there is a defined trusted path.
If money is a concern, it is worth a look:)
Answer: The Google Authenticator needs a remote system to validate the entered otp value.
This could be a remote site, a server or in the easiest case it is the pam-google-authenticator, which stores the secret key in the home directory of the user.
You can have OTP for free and as open source. Take a look at privacyidea. It works as a backend, can assign different kind of authentication devices to users from some user sources.
You can roll hardware tokens, smartphone apps (google authenticator), email or sms to the users. As each user can have a different type, you can decide which user gets which security level. You can mix hardware tokens and smartphone apps etc...

Remote administration methods


How is crypto Mining actually validating the block?

Question: As far as I understand in crypto-mining you are trying to find the nonce such that the hash starts with some amount of zero's. I do not understand how this nonce is used to actually validate anything.
Answer:
How is crypto Mining actually validating the block?

It isn't.
Before a miner starts mining a block template, they must have already have validated the data in the block template. They must already have checked that the data in the block template is valid. That each piece of data in it already passes all the Bitcoin rules.
Mining a block successfully acts to confirm transactions in the block but confirmation of transactions is completely different to validation (AKA verification) of transactions and blocks etc.

in crypto-mining you are trying to find the nonce such that the hash starts with some amount of zero's.

That is not true for Bitcoin. In Bitcoin, miners find a set of data, including nonce and other values, whose hash is less than or equal to a target value. There is no measuring of the number of leading zeroes.

I do not understand how this nonce is used to actually validate anything.

It isn't used in the way implied by the framing of your question.
See answer by chytrik The nonce is just a meaningless number whose value can be varied by the miner in the hope of finding a value that causes the hash of the whole block to be less than the target. It is part of the block data that all other nodes hash to validate that the block data does indeed have a hash less than the target, as it should. As chytrik noted, there are a large number of other characteristics of the block contents that are  also each separately validated.
Answer: In the context of your question, you can think about mining in two distinct ways:

the act of building block templates and 'mining' to find a valid block (this done by miners)
the act of validating a block that another node has told you about (this is done by network nodes)

For miners that are building blocks, the nonce isn't used to validate anything per say, it is just a piece of data that can quickly be varied to produce different hash results for an otherwise unchanged block structure. This is to say, miners can create a block template, and then quickly vary the nonce to produce many slightly different versions of the block, each of which will have a distinct hash. Hopefully they can find a block structure (which includes a specific nonce) that leads to a valid hash.
For nodes that are validating blocks, there are many rules that the block is checked against to see if it is valid. One of the rules is 'does the block header produce a valid hash?' (ie, one that is below the target value). Since the nonce is a component of the block header, you could say that the nonce is needed to validate the block.
Note though, there are many other rules for validity that the node will run through, that do not utilize the nonce in any way.
Comment: could you please clarify what you mean by building block templates?
Comment: A 'block template' is the name for the block structure that a miner will create when trying to find a valid block. The block template will be an otherwise valid block full of whatever header and transaction data the miner chooses to add to it, and the miner will then 'mine on that template' by iterating the nonce (and 'extranonce') in the hopes of finding a hash that will be counted as a valid block on the network.


Are we already moving faster than light?

Question: Okay, so the speed of revolution of earth around sun is 30 km/s[1], speed of revolution of sun around milky way's center is ~200 km/s[2], speed of rotation of milky way is 828,000 km/h[3] i.e. 230000 m/s. Since speed of light is 300000000 m/s, so on an even bigger scale (bigger than clusters) are we already moving faster than the speed of light? Or am I totally wrong?
Comment: Links are here: 1 - https://www.scientificamerican.com/article/how-fast-is-the-earth-mov/
2 - http://www.iop.org/activity/outreach/resources/pips/topics/earth/facts/page_43079.html
3 - http://www.space.com/19915-milky-way-galaxy.html
Answer: Short Answer

NO.

Long Answer -

The Earth "wobbles" on its polar axis.  This motion is not relevant (IMO) to the calculations needed to return to earth from interstellar space as it is an "in situ" motion, but it exists.
The Earth revolves {spins} on its axis. For these calculations we will use the equator with a circumference of approx. 25,000 miles. One rotation of Earth is approx. 24 hours. Again this is "in situ" motion so not relevant to space travel, but adds to our "stationary chair" model
25000/24 =1041.7 MPH
The Earth is orbiting the Sun once a year. The circumference of the Earth's orbit is approx.  607.6  million miles {or 940 million kilometers}. One year is approx. 365 days
365 days X 24 = 8760 hours
607,600,000/8760 = 69,360.73 MPH

So far we have basically 3 Directions of Motion {Wobble, Spin and
  Orbit} and a combined speed of 1041.70 + 69,360.73 = 70,402.43 MPH for
  a person sitting in a chair at the Equator.

The sun {and hence the solar system} is moving towards the constellation Hercules, namely to the star Lambda Herculis at 12 miles per second {or 20 kilometers per second} which is 43,200 MPH
The Solar system is also moving upwards, at 90 degrees to the plane of the Milky Way, at 4.34 miles per second or 15,624 MPH. But we are actually leaving the Galaxy, out about 50 light years now and will be moving out to 250 light years before it reverses. Details of the mechanics of this are explained in the link below. We also crossed the Galactic plane 2 million years ago.
The Solar system is orbiting around the Galaxy at an "estimated" speed of 124 miles per second {or 200 kilometers per second} which is 446,400 MPH. The way that figure has been calculated can be found at the link below.
So our "armchair Astronaut" is now moving through 6 different directions and a combined speed of approximately 574,585 MPH

69,361 MPH Spin and Orbit    43,200 MPH Towards Lambda Herculis
  15,624 MPH Perpendicular to Galactic Plane  446,400 MPH Orbiting the
  Galactic Center {or Galactic Spin Rate} 574,585 MPH  or 256862.478 m/s Speed of Earth
  within Our Galaxy

<code>light's= velocity = 3*10^8 m/s
So the ratio = 256862.478 / 3*10^8 = 0.00085620826
</code>
Answer: Short answer: no.
Whenever you mention a speed you must state what you are measuring the speed relative to. When a traffic sign says maximum speed 50kph it means relative to the Earth's surface. In measuring speed in space there is no such obvious frame of reference. The theory of relativity does not allow objects to move through space relative to each other, at speeds greater than the speed of light.
For objects inside the galaxy, the force of galaxy dominates their motion. We are in orbit in a galaxy, but our speed, relative to every other part of the galaxy is well below the speed of light.
For greater distances, the Hubble flow dominates motion: distant galaxies are moving away from us. The more distant galaxies are moving away from us faster. Galaxies more than about 4 billion parsecs (or 13billion light years) would be moving away faster than the speed of light. This doesn't break the theory of relativity as spacetime is being stretched between them and us. Objects can't move through space at speeds greater than the speed of light, but if the spacetime between objects is expanding, then they can appear to be moving faster than light, depending on your point of view.
None of this answer should be taken as contradicting the short answer above.
No, we are not moving through space faster than the speed of light relative to any object in our frame of reference.
Answer: You're totally wrong, but it's a good question.  Leonard Susskind actually uses something like the scenario that you're referring to in order to demonstrate how to add velocities when things like special relativity (which is a little different from what you're talking about, but similar enough for this discussion) are of concern.  Here are some links to the math behind adding velocities in special relativity (again, not technically what you're talking about but similar enough).
http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.html
http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/einvel.html
Nothing in your reference frame (pretend you're an observer for whom the sun is moving at the very, very, very limit of the speed of light) can travel at a speed faster than the speed of light (in a vacuum).  A lot of people can describe the consequences thereof very well (well enough to have actually made sure that it's a solid theory anyway), but I don't think anybody knows exactly why the speed of light acts like a cosmic speed limit.
EDIT:  Here's the Susskind lecture: https://www.youtube.com/watch?v=qfTJP7Soto4