How does White "waste" a tempo in the Botvinnik-Carls defence in the Caro-Kann?

Question: In this Hanging Pawns video, Mr. Tomic around 1:40, makes a statement, "White actually wasted three tempi to play e4, d4 and e5 so this takes away a tempo for White in exchange for a sacrificed pawn…" I don't understand. Why are the tempi wasted? Like, White has good control over d6 and more space even though the centre is damaged. In general, I had thought that a series of moves like Bf5 and then Bc8 was what losing a tempo meant. Can someone help me here?
Answer:
Why are the tempi wasted?

They were not strictly speaking wasted, they were spent and when White played dc they were exchanged. It is tempting to suggest that Tomic's mother tongue is not English and that he misspoke. However I think he is making a subtle point.
White has spent 3 tempi (e4, d4, e5) on building an impressive center. When Black plays c5 White has a choice. Play something like c3 and preserve the center or take the free pawn when the previously impressive center crumbles away to almost nothing.
This is the sense in which Tomic is saying the moves were "wasted". The impressive center those moves built has gone. However in return White has an extra pawn. They weren't so much wasted as the strong center was exchanged for an extra pawn.
Answer: Normally we say a player is losing a tempo in the opening when he's doing a move doesn't help development. Most players wouldn't call those moves "wasted" tempi, since they do indeed help with development. They're not development moves themselves so that's probably where the author is coming from, but they open up options for the bishops.
The only move which could perhaps be considered a wasted tempo is e5, but it still helps White get more space. Note that Black's moves weren't developping moves either
Anyway I wouldn't overthink it too much. How the position was reached or what the current "tempo count" doesn't really matter (specially with this kind of locked central structure). We should focus instead on the resulting position and the plans available for each side. The effectiveness of those plans and the actions the opponent can take against them is what will determine the evaluation of the position.

How does White “waste” a tempo in the Botvinnik-Carls defence in the Caro-Kann?


Circuit to test ICs at home? (74hc04, 74hc08, 74hc32)

Question: I have the above IC and I want to check them before using them. I don't have access to a lab currently and I only have access to the usual stuff (LED, resistors) and a simple ammeter/voltmeter. What can I do to test them? Obviously(?) the below circuit doesn't work.
Answer: 7400 series ICs take a bit of getting used to, as they are not as straightforward as, for instance, 74HC00 types.
Here are circuits to use with, for instance, the 7404 and 7400.

You'll note that the input switches provide a LOW input when closed, and the output LEDs are ON when the output is LOW. If this gives you too much trouble mentally, use unused inverters to switch the input and output polarities. But keep the switch and LED connections as they are.
TTL inputs are best driven by pulling them down or letting them be pulled up with a (obvious name, here) pullup resistor. usually in the range of 1k to 10k. And TTL outputs are much better at sinking current rather than sourcing it, so don't try to drive an LED output to ground.
Answer: If your parts are really 7404, 7408 and 7432 (with no letters other than possibly L or LS in the middle, like 74LS04)  they are bipolar TTL logic, and require a 5 volt power supply for correct operation.
The inputs of bipolar TTL parts will usually appear as logic High (1) when not connected.  You must connect the inputs directly to ground to have them seen as a Low (0).
If the parts have a C in the middle (74C04 or 74HC04), they are CMOS, and the inputs are very high impedance, and will be in an unknown state when not connected - they must be connected to the positive supply for a High, and to ground for a Low.
Comment: It is important to give the correct part numbers!  Those parts are CMOS, so my last paragraph applies.  The 74HC parts can use a power supply between 2 volts and 6 volts.
Comment: Hd74hc04p, hd74hc32p, sn74hc08n
Comment: Then shouldn't the diagram I drew above work?
Comment: You do need a current-lilmiting resistor (470 Ohms or so) in series with the LED, but with pin 1 tied to Vcc, the output of the inverter on pin 2 will be Low, so the LED won't light.  Also, ALL inputs on a CMOS chip (even if you aren't using the associated gate)  MUST be connected to either Vcc or Ground (or to a logic output).
Answer: Seems like you got an arduino. You can proceed like this for 7404. Get the pinout correct. Here is the pinout diagram:

Wire up pin 7 to GND and pin 14 to VCC of arduino. You are halfway through.
Connect an LED to pin 1 and pin 2 each (along with current limiting resistors. 470 ohms will work fine). Now take a wire and connect pin1 to VCC. LED on pin1 should light up and LED on pin2 should remain off. Now remove the wire and connect pin1 to GND this time. LED on pin1 should be off and LED on pin2 should light up. This verifies a working gate.
You need to repeat it six times to check all gates.
Similarly, you can think about all other ICs. It's just logic High and Low. Write the truth table, get the pinout and follow the same pattern.
Comment: Where should I connect the LED on pin 2 (of 7404) ?
Comment: Positive of LED to pin 2. Negative to the GND via a resistor. i.e. Negative to resistor, resistor to GND.


Change the rotation of single-phase (split-phase induction motor)

Question: In order to change the rotation of the single phase induction motor, the connection to one of the stator windings(starting winding and main winding) is reversed. But later we cut the starting winding ,so how is it possible to reverse the direction of rotation of the single phase induction winding?
Answer: You have to stop the motor before you can reverse it.
That lets the starter winding establish the new direction (and if the starter winding is disconnected by a centrifugal switch, it lets the switch turn on again.
Comment: That's right, you need to arrange the reversing yourself.
Comment: -After stopping and starting again, do I need to change the connections to the starting winding , so that the motor can run in opposite direction? Centrifugal switch can connect and disconnect the starting winding but it can't change its connection, isn't it?
Answer: Capacitor and split phase start induction motors don't need the start winding to run.
They need it only to get them started to one direction. The start winding has a phase shift against the run winding. Without the start winding the motor will hum and burn,
unless it gets the momentum some other way.
It is very dangerous to spin a single phase motor that is plugged in and not running.
Once it gets direction, it starts immediately.
Similar is a 3 phase motor that loses one phase, will continue to run as a single phase motor until stopped.


Why is $\frac{\sqrt{x+1}-1}{x}$ equal to $\frac{1}{\sqrt{x+1}+1}$?

Question: I'm working with the expression $$\frac{\sqrt{x+1} - 1}{x}.$$ According to Wolfram Alpha "alternate form" section (http://www.wolframalpha.com/input/?i=%28%28x%2B1%29%5E1%2F2-1%29%2Fx) it is equal to $$\frac{1}{\sqrt{x+1} + 1}.$$ How can I go from one expression to the other?
Answer: $$\frac{\sqrt{x+1}-1}{x}=\frac{\sqrt{x+1}-1}{x}\times\frac{\sqrt{x+1}+1}{\sqrt{x+1}+1}=\frac{x}{x\left(\sqrt{x+1}+1\right)}=\frac{1}{\sqrt{x+1}+1}$$
Comment: I'd check the domain restrictions, @servabat. Also, note that the second equality follows from the *difference of two squares*.
Comment: Was not specified, and I think ones should always consider the largest (so here $\mathbb{C}$) when not specified. However, because the function has a limit in a point doesn't mean that that function is defined in that point and yet, while you don't specify it, it is not defined. So because you find a limit in a point doesn't basically mean it is in the domain. By the way, there was no need of L'Hospital or anything else because basically you have an equality so the limit is the value of the function at the point, which you can easily evaluate in the first expression.
Comment: (+1), notice however that while the domain of the first is $\mathbb{R}\backslash\{0\}$, the domain of the second is $\mathbb{R}$ (I guess it could be important depending on what you do :?)
Comment: @servabat - For the function to be real-valued (which I *assume* is supposed to be the case, although it's not stated explicitly), its domain must be $\{x\mid x\ge-1\}$, not $\mathbb{R}$. Using L'Hopital's Rule, one finds $f(x)=0$ as $|x|\to0$, i.e., $\{0\}$ is included in the function's domain.
Comment: Because in the second expression the domain is narrowed doesn't mean it will change the limit.
Answer: Multiply the top and bottom by the conjugate $(x+1)^{1/2}+1$
Answer: Hint $\ $ Rationalize the $\, \color{#c00}{numerator},\,$ in exactly the same way  one rationalizes denonominators, i.e. multiply both by the "conjugate" $\ \overline{1-\sqrt{x+1}} \,=\, 1+\sqrt{x+1}\,$ of the numerator.
Remark $\ $ Though not used as frequently as rationalizing the denominator, this does prove useful in various contexts, e.g. specializing the quadratic formula when the leading coeff $\,a\to 0.$
$$\frac{-b\pm\sqrt{b^2 - 4ac}}{2a}\ =\  \dfrac{2c}{-b \pm \sqrt{b^2-4\:a\:c}}$$
As $\,a\to 0,\,$ the latter gives the root $\,x = -b/c\,$ of $\,bx+c\,\ (= ax^2\!+bx+c\,$ when $\,a=0).$


How to design a database schema for storing text in multiple languages?

Question: We have a PostgreSQL database. And we have several tables which need to keep certain data in several languages (the list of possible languages is thankfully system-wide defined).
For example lets start with:
create table blah (id serial, foo text, bar text);

Now, let's make it multilingual.
How about:
create table blah (id serial, foo_en text, foo_de text, foo_jp text,
                              bar_en text, bar_de text, bar_jp text);

That would be good for full-text search in Postgres. Just add a tsvector column
for each language.
But is it optimal?
Maybe we should use another table to keep the translations?
Like:
create table texts (id serial, colspec text, obj_id int, language text, data text);

Maybe, just maybe, we should use something else - something out of the SQL world?
Any help is appreciated.
Comment: Possible duplicate of [Schema for a multilanguage database](https://stackoverflow.com/questions/316780/schema-for-a-multilanguage-database)
Answer: I think it is best if you create two tables. One for languages, one for ids and so on.
first_table( id )
second_table( s_id, id_first_table, language_id, language_text)
Comment: That is how I attempted to do it so far. But I'm stuck on full-text-search indexes. If I had the lang columns inline (like in the first example) I could easily create tsvectors for them.
With the second schema this is harder, and (I think) impossible
when the fts-index needs to be on concatenation of two columns.
Answer: Here's a great article the Mozilla developers put together on making their database multilingual.  It's specific to CakePHP, but the info can easily be applied to other systems.  Also, note that it makes SQL queries significantly more complex, which is a drawback.  That will generally be true regardless of your i18n implementation, though.

Part 1
Part 2
Part 3
Comment: The last link is the only one with content regarding data modelling.


Which Bottom Bracket do i need? 107mm 41

Question: I cant´t find a Bottom Bracket for my Cube two 15 2017.
It need a 107mm x 41.
Please help me.
Comment: Need more info. Is the 107 referring to the length of a modular spindle? What cranks?
Comment: @NathanKnutson One description, but not original and not sure if correct. Crank listed as XO1 DH, probably GXP spindle. BB listed unhelpfully as "8mm drop, press fit" https://mtbdatabase.com/bikes/2017/cube/two15/2017-cube-two15-hpa-sl-27-5/
Answer: One first piece of advice to cyclists would be to Google your bike's model name and the phrase "bottom bracket". This will often show results containing the specification. However, in this case, it's unhelpful. Cube's current Two15's specs (or at least, one randomly selected version of that range) do reference a RaceFace BB107.
I am not familiar with this standard. The "41" you referenced may be a reference to the diameter of the BB shell. I believe only the BB86 standard corresponds to 41mm diameter. Now, "107mm", if it refers to the BB shell width, doesn't correspond to the road or the usual MTB standard, but you seem to have a downhill bike. This BikeRadar article says that the BB86/BB92 standard may also accommodate a 107mm wide BB shell.
You could try taking the cranks off, if able. There are often markings on the bottom bracket shell that may be obscured by the crank. If you have calipers, you could confirm the shell width and diameter (or a measuring tape might be made to work). If not confident, a bike store could do this for you, and a lot of us would be getting a store to change the BB anyway.
From there, you would need to know the diameter of your crank axle. It isn't clear what you have, from the spec I listed in the comments. This would be something probably better measured. I speculated that you might have a GXP spindle (because one version of the specs listed a SRAM crankset, and in 2017 they should have been offering GXP spindles, but I don't know how common 30mm spindles were for SRAM). A bike store would likely recognize the spindle type on sight.
I believe the cups are the same across all BB86-type BBs no matter what the shell diameter. If this is correct, you'd search for BB86 in combination with your crank axle width. Or, for example, Wheels Mfg's page will direct you to pages for Shimano, GXP, SRAM DUB, or 30mm axles.
Other Google-fu type advice could include trying to figure out what BB type Cube bikes in general use. However, there's the risk that a manufacturer might change to a different type of BB at some point (e.g. Trek popularized BB90, but they were the only one to use it and it wasn't compatible with 30mm axles, and they are changing to T47), and you don't know when that point is. Or they might use different BB types at different spec levels and you might miss this. Personally, I maintain a list of critical parts and specs in Evernote just in case I forget. I checked my own bike's BB (it's a Parlee Chebacco, PF30 BB), but without taking the cranks off, the cups' only visible markings are "SRAM DUB", which is insufficient information if I didn't remember the BB standard. (This describes a crank manufacturer and an axle type, i.e. the 28.99mm DUB axle, but not the shell type.)


How do I write a cadence without any context?

Question: I am studying for my online RCM theory exam, and since I have no contact with my piano teacher I've been correcting with the answer book. My answers and the answers in the book are very different. I have followed all the instructions I can, but there is no other context within the exercise, as to wether to write a perfect authentic cadence, inverted cadence, etc. But in the answer book, there is only one right answer. What am I missing?!
The question only asks to write an authentic cadence, does not specify what kind, and then says only one specific kind is right. Is this correct? Or are all types of cadence correct?
Comment: Cadence names are different on each side of the pond. And can bring slight confusion. Posting the question and answer would be helpful.
Comment: Yes. It would be really helpful if we could see the answer book.
Comment: Is your question how to get the right answer for the textbook or how to understand cadences? Post images of your answer and textbook if you want to know what's up with the textbook answer key.
Comment: You may find this site useful: https://www.musicnotes.com/now/tips/cadences-in-music-theory-the-4-types-explained/ Could you explain what you're writing vs what you're seeing in the answer book? I would expect a perfect cadence will be V(7)-I with the roots in the bass.
Answer: This answer is not about your textbook answer key, but cadences generally.
The names of cadences can vary, but the concepts don't.
First, identify a structural ending. For example, V to I is not a cadence... unless it actually ends some phrase or section. Look for phrase/section endings, then categorize their cadences.
Next, identify the two final chords. For all practical purposes the combinations are:

V to I for the various authentic types
and chord to V for half cadence
V to vifor deceptive/interrupted types

...replace I with i and vi with bVI in minor.
Finally, the melodic movements of the bass and soprano voices provide the detail for specific types. I prefer scale degree notation using a circumflex ^ for this part.
Bass ^5 to ^1 and soprano something ... to ^1 are the movements for perfect types. Sopranos ^1 ^7 ^1 or ^3 ^2 ^1 would both satisfy this type, it just needs to end on ^1.
When the chords are V to I but the melodic movement is anything not bass ^5 to ^1 and soprano ...^1 then the cadence is some kind of imperfect type.
Half cadences are any bass movement to ^5 with the soprano providing any other tone of the dominant chord. On the whole - or at least in some generic sense - I think this chord should be a simple triad V and not a dominant seventh chord V7. The point being the simple triad is stable and hence better for the stop of a cadence. An ending like ...V6/V V which then continues like V V7... is a typical example showing V is stable and V7 is active. Some might say that example is a modulation to the dominant and a retransition back to the tonic key. Call it whatever. The point is to be sensitive to the quality of the final dominant chord in a half cadence and the treatment of the subdominant ^4 around it.
Deceptive cadences for all practical purposes are bass ^5 to ^6 with the soprano on some tone of the submediant vi.
The plagal cadence is IV to I and...

really just a kind of codetta after an authentic cadence
or strictly speaking not classical style

Essentially, cadences are about phrase endings with the bass moving to ^5, ^1, or ^6 with the soprano providing some root position harmonization above with a fair amount of freedom except using ^1 for emphatic endings. When inverted chords are involved the cadences are "weakened" to some degree, or depending on the phrasing might be better described as "cadential harmony."
Something I have never read in a basic textbook, but seems really important to the understanding of cadences is the placement and purpose of authentic type cadences within the structure of a composition. Superficially an authentic cadence is just an authentic cadence, but within a composition's structure I see three main purposes:

establish a starting key
confirm a modulating phrase ending in a contrasting key
conclude in the original starting key

An opening often moves back and forth between I and V in a way that superficially might look like cadences, but is really best described as cadential harmony. This establishes a key. Obviously nothing is ending.
After establishing a key, a piece usually moves through some number of different, contrasting keys. The phrases involved modulate. These phrases seem to start in one key, but end in another. Often the passages use sequential harmony. An authentic cadence can end the phrase, but of course the music does not stop. In this sense the purpose of the cadence is not an ending so much as a confirmation the music is in a different key. After this confirmation the next phrase can immediately start up on new chords and modulate to yet another key. So, something starting in C major could then have a modulating phrase end like ...V7/ii ii followed by another modulating phrase immediately abandoning the key of ii, like ...V7/vi vi. The point is these cadences don't establish and continue in a new key. They confirm a key without continuing. You could say that they function like endings, but because the various keys are not the opening key of the piece the music continues.
That brings us to the concluding cadence. This seems straight forward. After the initial key is established, if you make a concluding cadence in that opening key, you're done. More than one cadence in the opening key should then be understood in terms or premature or redundant. Taken on the grand scale of a sonata, it's the recapitulation. After a concluding cadence, harmonic motion around the tonic - alternating V and I or IV to I, etc. - is likely to be considered a coda. Not really cadences, but an extension of the tonic chord.
All this may seem to have nothing to do with your question, except that you mentioned context. The context that really matter for understanding cadence is form and the structure of phrases. Simply categorizing cadences by two chords and some voicing details barely scratches the surface about the structural meaning of cadences.
Answer: When I learned harmony (in the UK), there were 4 types of cadence.   Perfect was V-I.   Imperfect rested on V.  Plagal was IV-I, the 'Amen' cadence.  And Interrupted was a frustrated Perfect, typically V-vi.
'Perfect' seems to have been re-named as 'Authentic'.  Fair enough.  And Authentic has two variants, 'Perfect Authentic' where the bass goes 5-1 and the top voice goes 7-8.   And 'Imperfect Authentic' where at least one of those criteria isn't met.  Imperfect Authentic has four sub-types.. heck, I'm tired of copying out the textbook.  Read about them here:
https://www.musicnotes.com/now/tips/cadences-in-music-theory-the-4-types-explained/
Right, got that.
If the question simply asks for an Authentic cadence, and there are no other factors (like a given melody line that DOESN'T go 7-8) write a Perfect Authentic one.
If there's still confusion, please add the actual question and specimen answer to your question.
Comment: Note that that website perhaps isn't the most accurate source. They list four cadences in Happy Birthday, and to me there's only one; and one of the cadences they show in the music isn't even one of the four types they go on to explain!


Does "shall no longer be" imply "forever not?"

Question: Can "no longer" refer to a finite, forseeable time period, or does it indicate a long-term finality?  For example, if someone says, in anticipation of a large meal, "I shall no longer be hungry," does that imply that they will never be hungry again?
Comment: Erm... It's more the *"I shall...be"* part that could be taken as implying "now and forever". I imagine most of these several thousand written instances of [*"I **am** no longer hungry"*](https://www.google.com/search?q=%22I+am+no+longer+hungry%22&btnG=Search+Books&tbm=bks&tbo=1) will be in contexts where the speaker has either eaten enough already, or just undergone some experience that's put them off their food. But usually they'll be hungry again tomorrow, and be looking forward to their dinner.
Comment: @FumbleFingers Good point - I'll edit the question accordingly.
Comment: No. I suspect that out of all the people who write [I am no longer employed](https://www.google.com/#q=%22am+no+longer+employed%22). many of them expect to work again someday.
Answer: Examples based around "being hungry" are problematic. In one way of looking at it, we might say a person who never experiences "being hungry" is lucky - if what we mean is he will always have enough to eat.
But there are plenty of people whose very lives are threatened by the fact that they don't experience the natural feeling of "being hungry" and/or lose their sense of taste. Lamisil/Terbafine, for example, can have these effects (sometimes permanently, and it's much worse than most people imagine). It's obviously hard to eat enough if you never feel hungry, and eating itself has become truly revolting. So let's look at OP's construction with something a bit less awkward...

Becks: "If I give away all my money I will no longer be rich"
   Posh: "Don't worry pet. With your $50M salary from Paris Saint-Germain we won't be poor for long"

In short, it's not that "no longer" particularly implies anything about the future. All it means is that something that was true will stop being true. Whether it becomes true again in the future depends entirely on what kind of thing it is, and the uncertainties of how the future plays out.
Answer: Actually, I think you're looking at the construct backwards. "No longer" implies that your statement was not true at some point in the past. For example, "I used to be hungry, but I am hungry no longer." It says nothing about the future outside of context.
Comment: I think *you* have got something "backwards". Surely what you mean is *"No longer" implies that your statement **was true** at some point in the past* (but is no longer true).
Comment: I'm not sure if you read the same question that I wrote.
Comment: @FumbleFingers Only if you include the "no longer" as part of the statement; I can see why this answerer would disinclude it. That said, I agree that this answer, while good, would benefit from clarification.
Comment: @user867: Not sure what you mean there. Emmett's second sentence is unquestionably invalid. His example in the third doesn't correspond to OP's (OP asked about ***will** no longer be*, not ***am** no longer*). That's 2 out of 4 sentences in the answer that are are worthless or worse. Now you're making me look at it more critically, I feel I have no option but to downvote it.
Comment: @FumbleFingers Now that I re-read what I wrote in my comment, I see I was getting confused, myself. I do think there's the foundation of a good answer here, but it definitely needs some expansion.


Geometric Interpretation of Determinant of an Inverse Matrix

Question: The $\mathbf{A}$ be an $n\times n$ full rank matrix. Then, the (signed) volume enclosed by the rows (or columns) of $\mathbf{A}$ is equal to $\det(\mathbf{A})$. My question is, what is a geometric interpretation of $\det(\mathbf{A}^{-1})$? What would be the parallelotope defined by $\mathbf{A}^{-1}$ and in which way is it related to the parallelotope defined by $\mathbf{A}$?
Answer: The determinant is multiplicative, i.e. $|(AA^{-1})| = |1| = |A||A^{-1}|$ and as such $|A^{-1}| = |A|^{-1}$ which shows the intuitively obvious fact that if the determinant is the signed area of the image when transformed by $A$ of the unit cube with sides given by the basis vectors of the space. Clearly if $A$ grows this cube by a certain amount, then $A^{-1}$ must shrink it by the same amount, as when they are applied together they should give the unit cube back.
Answer: It is no different from a multiplicative/divisive bijective relationship.
If $ V_2 = 3\; V_1$ ,then $ V_1 = \frac 13 \; V_2. $ Under action of the determinant volume expands or contracts by the same factor.


Why can't light induce a current while microwaves can?

Question: Microwaves can induce current in a coil of wire why cant visible light do the same?
Answer: Like radio waves, the electric field of the optical light acts on the electrons in a material and can cause them to move. But visible light has a much shorter wavelength than radio waves (about $10^6$ shorter) and so it doesn't drive macroscopic currents. Moreover, the conductivity decreases, which we can see in the Drude Model:
$\sigma (\omega )={\frac {\sigma _{0}}{1+i\omega \tau }}={\frac {\sigma _{0}}{1+\omega ^{2}\tau ^{2}}}-i\omega \tau {\frac {\sigma _{0}}{1+\omega ^{2}\tau ^{2}}}$
where $\omega$ is the light frequency, $\tau$ is the relaxation time (due to scattering and related to the carrier density, temperature, etc.), and $\sigma _{0}=\frac {nq^{2}\tau }{m}$ is the effective DC conductivity ($n$ is the number density and $m$ is an effective mass which can be different for electrons and holes depending on the crystal).
We can see that when the frequency $\omega$ is large (like for optical waves) the conductivity goes to zero. This happens because at really high frequencies the electrons do not have time to respond to the field and so they no longer (appreciably) move back and forth. Above this frequency the material becomes transparent (identical to the behavior at the critical frequency in plasmas).
Answer: There is the developing field of nanoantennas. It is now possible to manufacture arrays of Yagi-Uda antennas on micrometer length scales. And nanoclusters like red gold in glass have been made since Roman times.
The problem is a bit what to do with such currents. There is no electronics to act as a radio tuner at such frequencies. But there are ideas to make rectifying nanowires of GaAs and use them to harvest solar energy.

Why can’t light induce a current while microwaves can?


how does a helicopter get forward thrust?

Question: Just passed a helicopter on my way to work. We have read in some detail how an airplane gets forward thrust and lift by deflecting air. How does a helicopter with horizontal fans achieve that ?
Comment: Please edit the part "an airplane get forward thrust and lift by deflecting air".  We need to understand what you know to helpfully answer the question, and the degree to which this reflects typing errors versus gaps in understanding is indecipherable.
Answer: The fans are not fixed to be always horizontal. The pilot is able to control the deflection angle of each fan, and this deflection angle causes air to be pushed in one preferential horizontal direction which gives thrust.
Comment: To add to lurscher's post: watch this http://www.youtube.com/watch?v=I9ScVZ437xA which shows how by adjusting the angles of attack of *individual fan blades* you can preferentially generate more lift on one side than the other.
Comment: This is misleading. The deflection angle does not directly push air horizontally. It creates a lift imbalance, torquing the entire assembly (with a ~90 degree phase lag as per the cross product). Horizontal thrust is the result of the plane of the blades not being horizontal.
Answer: In general, the forward thruswt is achieved by tilting the entire helicopter forward.  This converts some of the lift produced by the main rotor into a forward component of force.  The same is true for turns.
Yes, the swashplate may be used to create a thrust imbalance; but this imbalance does not provide any horizontal forces.  It merely creates a force imbalance which tips the helo slightly, so that a component of the upward force of the main rotor gets converted into a lateral force.
Take a look at any helo moving with any kind of rapid forward velocity and you will see that the entire craft is tipped noticably forward.  Same with sharp turns: the helo tilts noticably in the direction of the turn.
Comment: The same is true for airplanes to a certain degree. The way airplanes turn is by adjusting the various elements on the wing and the tail to chage the *roll* of the aircraft, and then the "lift" provided by the wings are no longer vertical, with the horizontal components allowing the plane to turn. Similarly, the swashplate of the main rotor on a heli is used to adjust the pitch and roll of the aircraft, with the tail rotor used to adjust the yaw.
Comment: Excellent point Willie.  I was going to add that and decided not to clutter up the post by going into airplanes; but your point is germaine.


what is the etiquette to thank brothers wife in disseration acknowledgement

Question: I helped my brother in law financially for his Ph.d and in dissertation doc, he simply mentioned me as his brothers wife. (not sister in law). is that normal to not call me sister in law after 6+ years of marriage to his brother? I dont see why it would be weird to call me sister-in-law
Comment: Ask your brother in law, I think.
Comment: These are just two different ways to word the same thing. I wouldn't worry about the distinction.
Comment: sister-in-law means wife of brother OR sister of husband. By stating the relationship explicitly, he gives credit to the correct person.
Answer: As far as I know, there is no particular etiquette or customs regarding this choice of words in thesis acknowledgments. So the answer to this question does not depend on any peculiarity of academia.
In view of this, I suggest you to ask your question on [interpersonal.se]; they may have more relevant advice.


Can I invest in GLBSE on GLBSE?

Question: With the new design it's starting to take off. I want in on GLBSE itself, is this possible or are there any plans for it to happen?
Comment: GLBSE has closed.
Answer: GLBSE (or BitcoinGlobal, to be exact) has shares, but the shares aren't managed on GLBSE yet and the current bylaws prevent the shareholders from selling shares to non-shareholders without a majority vote. Moving the shares to GLBSE is planned, and I expect public trading to be allowed eventually.
(I'm treasurer of BitcoinGlobal and a shareholder.)
Comment: @Lohoris BitcoinGlobal shares existed before GLBSE did, so they couldn't initially be listed. It was planned to move them to GLBSE ASAP, but few of the shareholders cared to use GLBSE's previous terrible system. Now that GLBSE is easy to use, all of the shareholders should be able to sign up and have their shares credited to them.
Comment: I find it quite shady for GLBSE not to be listed on GLBSE itself, like if they didn't fully trust their own system.

Can I invest in GLBSE on GLBSE?


Add blog posts in a Nuxt content blog

Question: I want to create a blog using nuxt since I am familiar with vue js. I have looked at nuxt content module. I understand that i can create markdown blog posts. But, I am confused. If I deploy the app, then How can I add new blog posts?
Thank you.
Answer: You add the posts before deploying, in your source code, as described in Nuxt Content's documentation. Then you have to build the Nuxt project and (re)deploy the site.
If you need the ability to edit your blog after deployment, in your browser, and redeploy it after every editing automatically, you would need a service which has access to the source code and has ability to build & deploy your site. Netlify CMS can be one such solution, (especially) if your site's source code is on GitHub. (It works with private repositories too.)
Comment: Ok I got it. Thank you.

Add blog posts in a Nuxt content blog


Single slit and double slit interference

Question: I skimmed this and this about the title subject but I am still unclear. What are the differences and similarities between single slit and double slit interference patterns?
Comment: You should read a few chapters of a book on fourier optics, not skim a few answers here.
Answer: The expressions for single slit and double slit Fraunhofer diffraction look like:
$$I(\theta )=I(0)\ \text{sinc}^2\beta$$
$$I(\theta)=I(0)\ (\text{sinc}^2\beta)(\cos^2\alpha)$$
where $\alpha=(\pi a\sin\theta)/\lambda$ and $\beta=(\pi b\sin\theta)/\lambda$ and as usual $a$ and $b$ represent the distance between the slits and width of slits. Also
$$\text{sinc}( u)\equiv\frac{\sin u}{u}$$

OP is asking for the similarity and difference between the patterns. Now These are two different functions but you can plot them to see what are differences and similarity. This task, I left, to OP. :) You can  find the plot here. Focus on envelope for similarity.
Answer: Take a look at single edge Diffraction patterns: https://images.app.goo.gl/RSYzmToh96thgAfM6
A single slit has two edges with diffraction patterns going opposite directions.
A double slit has four edges with diffraction patterns going opposite directions and overlapping each other.


Loading filepicker widgets fails

Question: I'm having a weird issue. I'm using the filepicker 'pick' widget to upload a logo. When the page is first rendered, the widget is shown. However, if I navigate away from the page and visit it again, the widget is not rendered. I have to explicitly clear the cache to see it again. Any help would be greatly appreciated.
Answer: Is your app using something like Pjax to load the pages?
Filepicker initializes the widgets on page load. If the page is loaded via something like
pjax, then the widgets will need to be re-initialized everytime you navigate to that page.
eg:
filepicker.constructWidget(document.getElementById(idOfElementToBeConvertedToWidget))
I've had to do this on an app that I am building that uses Pjax.

Loading filepicker widgets fails


Feynman Diagram for Bragg Equation

Question: Did Feynman ever derive the Bragg equation as a particle representation using Feynman diagrams? And where is it available? I spoke to Freeman Dyson and he couldn't recall.
Answer: Did you look at http://birdtracks.eu/ ?
Its a massive compendium on feynman diagrams
Comment: Thank you, but a search of text doesn't show any Feynman diagram for the Bragg equation.

Feynman Diagram for Bragg Equation


Logistic Regression Model on Test Set - in Titanic Data Showing Error

Question: I have built the model on Titanic Data set , with  Logistic Regression Succeffullly and it is giving prediction on training set , but unfortunately I am unable to implement this on test data set.
Following code for reference :
training = training[['PassengerId','Sex','Embarked','Pclass','Age','SibSp','Survived']] # 0.78
X = training.iloc[:, :-1]
y = training.iloc[:, -1]

from sklearn.compose import make_column_transformer
from sklearn.preprocessing import OneHotEncoder
ct = make_column_transformer((OneHotEncoder(), ['Sex', 'Embarked']), remainder = 'passthrough')
X = ct.fit_transform(X)

from sklearn.preprocessing import StandardScaler
sc =StandardScaler()
X=sc.fit_transform(X)

from sklearn.linear_model import LogisticRegression

logreg = LogisticRegression(solver = 'lbfgs')

from sklearn.model_selection import cross_val_score

cross_val_score(logreg, X,y, cv=5, scoring ='accuracy').mean()

As in the test data set , I don't have y data that means the predictive column so I introduced it with the help of null values.
But unable to take it forward, Can you please guide , how I can run Logistic Regression Model on test data set of Titanic.
Thanks a lot .
Answer: Why don't you use the predict function from the LogisticRegression model trained with the training data?
For example:
y_pred = logreg.predict(X_test)


Remove tomcat autostart

Question: When I run ubuntu, the tomcat server I have installed runs automatically and I have to switch it off manually. I want tomcat not to start automatically on boot. How to disable tomcat's startup on boot?
Answer: -> first: find out the name of the service. for example: tomcat or tomcat6
Than: try this:

sudo update-rc.d tomcat remove

You can use the following tool:
sudo sysv-rc-conf

http://dotgiri.com/2009/08/31/alternative-for-chkconfig-in-ubuntu-sysv-rc-conf-enable-or-disable-services-at-startup/
If this doesn't work, the next will work
1.) find out your current runlevel
runlevel

2.) (re)move the startscript from the runlevel directory
/etc/rcX.d (wher X is the number of the current runlevel) Example:
mv /etc/rc5.d/S90tomcat /etc/rc5.d/disable.S90tomcat

The script starts with S and an Number (for example S90tomcat), which means: S=stratscript for tomcat, Start at position 90.
Simply delete or move that script.
3.) Finally also remove the stop-Script (Kill Script) which looks like /etc/rcX.d/Kyytomcat where yy is an number between 0-99 and X is the runlevel, you still know.
mv /etc/rc5.d/K01tomcat /etc/rc5.d/disable.K01tomcat

Look at this
http://www.unixtutorial.org/2009/01/disable-service-startup-in-ubuntu/
Comment: Note: that the default tomcat service name is "tomcat7" in ubuntu 14. If your tomcat is tomcat6 you will need to do "sudo update-rc.d tomcat6 disable" else you will get error
Answer: I installed tomcat using this tutorial and following solution  worked for me.
Edit tomcat.conf
   sudo vim /etc/init/tomcat.conf

I changed start on runlevel value to
    start on runlevel []

Stop autostart
    sudo initctl stop tomcat

Answer: When the Ubuntu OS reboots, the Apache Tomcat Server will start automatically. This program setting can be changed by entering one of the following two commands.
sudo systemctl enable tomcat9
OR
sudo systemctl disable tomcat9

source: https://linuxhint.com/install_apache_tomcat_server_ubuntu/

Remove tomcat autostart


Programs for calculations in quantum mechanics and theory of relativity

Question: What programs do you recommend for calculations in the field of quantum mechanics, quantum field theory, relativity, string theory and loop quantum gravity?
Answer: QuTiP: Quantum Toolbox in Python
QuTiP is open source software for simulating the dynamics of closed and open quantum systems. The QuTiP library uses the excellent Numpy, Scipy, and Cython packages as numerical backend, and graphical output is provided by Matplotlib. QuTiP aims to provide user-friendly and efficient numerical simulations of a wide variety of quantum mechanical problems, including those with Hamiltonians and/or collapse operators with arbitrary time-dependence, commonly found in a wide range of physics applications. QuTiP is freely available for use and/or modification, and it can be used on all Unix-based platforms and on Windows. Being free of any licensing fees, QuTiP is ideal for exploring quantum mechanics in research as well as in the classroom.
All of the software mentioned in the preceding paragraph can be installed for Python 3.x from the default repositories in Ubuntu. For Python 2.x python-numpy is available for Ubuntu 20.04 and earlier and python-scipy is available for Ubuntu 18.04 and earlier. In Ubuntu 20.04 and later the QuTiP package can be installed from the terminal with the following command:
<code>sudo apt install python3-qutip
</code>
Ubuntu 20.04 will be the first Ubuntu release to include QuTiP in its default repositories. Ubuntu 20.04 is scheduled to be officially released in late April, 2020. This will be a long term support (5 years) release. All Ubuntu releases are supported by updates for free during their normal support period. After the 5-year free support period has ended there is optional Extended Security Maintenance for an additional 5 years via Ubuntu Advantage which is free for personal use on up to 3 machines.
The official releases of QuTiP can be downloaded at: http://qutip.org/download.html
For instructions on how to install QuTiP see: http://qutip.org/docs/latest/installation.html
Comment: Simply, I like to use Windows more.

And what about the calculations in other sciences (quantum field theory, string theory, etc.)?
Comment: [qft++](http://www-meg.phys.cmu.edu/williams/qft++/index.php/main_page) is a C++ package for numerical quantum field theory calculations.
Comment: Is C ++ the only tool available today?
Comment: C++ and Python.
Comment: I am very new to this toolkit. For Maple, Mathematica there are no such tools?
Comment: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/103802/discussion-between-karel-and-andrew-sol).
Comment: Is anything known about the use of Maple, Mathematica or Matlab?
Comment: You don't need MATLAB in Ubuntu, at least not in the beginning. Start with Octave from Ubuntu software. You can install MATLAB in Ubuntu later if you need it + matlab-support with `sudo apt install matlab-support`


Explain this interaction between a traveller, a boy and a bag of bread in Nepal?

Question: I aimlessly bumped into a youtube video. A traveller in Nepal seemed to call the poor little boy hiding behind a post an idiot? I don't understand what has happened between them? Is it a local scam or something?
Comment: Were you actually in Nepal when this happened? That would make it a LOT more interesting than if you were just watching YouTube from say, England or the United States.
Answer: Where there's tourism there's likely to be beggars - especially in poorer countries.
Sometimes these beggars will be "real" - people who are homeless and in need of help from others to survive.  Sometimes they are simply trying to swindle money from tourists, often as part of a larger ring - especially when children are involved.  Some people claim that the best way to help such people is to give them food rather than money - with the logic that if they are truly homeless and in need of help, then they will be thankful for the food.
In this case it would appear the tourist has simply found someone who is not in need of food.  He gave the food to the boy, the boy didn't want/need it, so he disposed of it by giving it to the dog.
Attempting to video the child and calling him an "idiot" benefits nobody, but unfortunately is the type of action you often see from some tourists.


As admin no longer able to "open with access"

Question: I was promoted to site collecton administrator on a sharepoint. Now I cant use the button "open with access" anymore. Previously I was user with read-write and there was no problem with using access to edit my list.
Answer: i know you have used it before but we do make mistakes, just incase make sure your looking at site level and within a team site! also make sure you have Microsoft Access 2010 Runtime installed.
Ok just incase you can try it this way,
open access:

click on open file, you should get a new dialog popup. Within the dialog select the dropdown button to show you different file formats. For you click on microsoft sharepoint foundation:

now go through the wizard setup to make the link, copy past the list url to re-establish the connection:

you should have the connection backup in sharepoint!
I dont see why you would have the "connect to access" grayed out and same with viso, the only other thing that i could think of is if the access for site collection admin is in a group that has limmited access to external applications but i wouldnt see why they would do that?
Comment: cool thank you very much. your way works fine. savind and editing. so I guess my problem is somehow related to my browser or missing requirements for start access from browser??
Comment: thanks for your fast reply. The only thing which changed for me was installing sharepoint designer 2010 and getting more rights. For example workflow settings are enabled for me now or export to excel . Just "open with access", "open visio" open schedule are greyed out
Comment: just ammended my answer
Comment: well could be browser issue, know to be with x64bit browser, are you doing it on 32bit? for some reason sharepoint lost the connection or its the browser version that is in conflict. either way glad to see that you got it working! grayed out could mean lost link, lost the runtime, version of browser or restricted access on sharepoint site becasue of a group that the site collection admin could be in
Comment: thanks. i am using IE (urgh) but am not sure whichbit-version. was already preinstalled. I will try reinstalling net framework... maybe that helps


What security technology do I need to protect my SSN database?

Question: I'm designing a web application. I need to make sure all my customer's SSN data is secure. Now I know HTTPS with SSL, I'm wondering what are its weaknesses? What else I need to provide a perfectly secure web interface? I'm going to host the server via Amazon EC2 or some other cloud service.
Comment: Does the web application need the SSN?  If possible try using an alternate identifier, encrypt and secure your database, and rigorously test and log your application for exploits.
Answer: HTTPS is only one part of the puzzle - securing the link between webserver and customer's laptop - and to be honest, it is the simplest bit, as web servers and browsers pretty much do this right, however you will need to enforce SSL v3 and approved algorithms.
In addition you will need at a minimum:

authentication to your web application for customers (username/password, token)
session management
validation of input (see questions on SQLi and input validation)
protection of your database (possibly encryption)
controls defined for developers, admins and others who have access
an assessment of resilience - if your customer cannot connect to the EC2 instance, they are DoS'ed
Comment: To help the mindset, think data at rest, data in storage, and data in transit.

You mentioned ssl (data in transit).
Rory added encryption (et al.) which can help with all three.


Ignoring unregister_worker in resque

Question: My rails app consists of an API server and an Admin server. Both make use of resque jobs.
In my local development environment each of them have a Procfile and are using the same redis server. The problem I have is that I cannot control which server is picking up which job. Each server has distinct queues, but they seem to be picked up in the 'unregister_worker' routine.
<code>/ruby-1.9.3-p194/gems/resque-1.24.1/lib/resque/worker.rb:459:in `unregister_worker'
</code>
I see this in my call stack and it leads to a ruby error since it doesn't know the class.
How can I tell resque to ignore an `unregister_worker'? Just to clarify I don't have a worker task associated with the '*' queue.
As a workaround I could run two redis servers locally as I do in my production environment, but I like to avoid that if I can.
Answer: Redis Namespaces do exactly that. In 'config/initializers/resque.rb' specify the namespace of the queue:
<code>Resque.redis.namespace = "resque:admin_server"
</code>
Found the solution here:
How do you start resque to use Resque.redis.namespace?

Ignoring unregister_worker in resque


Sample with constraint, vectorized

Question: What is the most efficient way to sample a data frame under a certain constraint?
For example, say I have a directory of Names and Salaries, how do I select 3 such that their sum does not exceed some value.  I'm just using a while loop but that seems pretty inefficient.
Answer: One approach would be to start with the full data frame and sample one case.  Create a data frame which consists of all the cases which have a salary less than your constraint minus the selected salary.  Select a second case from this and repeat the process of creating a remaining set of cases to choose from.  Stop if you get to the number you need (3), or if at any point there are no cases in the data frame to choose from (reject what you have so far and restart the sampling procedure).
Note that different approaches will create different probability distributions for a case being included; generally it won't be uniform.
Answer: How big is your dataset? If it is small (and small really depends on your hardware), you could just list all groups of three, calculate the sum, and sample from that.
<code>## create data frame
N <- 100
salary <- rnorm(N))
## list all possible groups of 3 from this
x <- combn(salary, 3)
## the sum
sx <- colSums(x)
sxc <- sx[sx<1]
## sampling with replacement
sample(sxc, 10, replace=TRUE)
</code>
Answer: You could face a combinatorial explosion. This simulates the selection of 3 combinations of the EE's from a set of 20 with salaries at a mean of 60  and sd 20. It shows that from the enumeration of the 1140 combinations you will find only 263 having sum of salaries less than 150.
<code>> sum( apply( combn(1:20,3) , 2, function(x) sum(salry[x, "sals"]) < 150))
[1] 200
> set.seed(123)

> salry <- data.frame(EEnams = sapply(1:20 ,
                                       function(x){paste(sample(letters[1:20], 6) ,
                                             collapse="")}), sals = rnorm(20, 60, 20))
> head(salry)
  EEnams     sals
1 fohpqa 67.59279
2 kqjhpg 49.95353
3 nkbpda 53.33585
4 gsqlko 39.62849
5 ntjkec 38.56418
6 trmnah 66.07057

> sum( apply( combn(1:NROW(salry), 3) , 2, function(x) sum(salry[x, "sals"]) < 150))
[1] 263
</code>
If you had 1000 EE's then you would have:
<code>> choose(1000, 3)   # Combination possibilities
# [1] 166,167,000   Commas added to output
</code>
Comment: Depending on what the dataset looks like, it may be possible to do some subsetting to shrink it before calculating combinations.  For example, you can get rid of any salaries that are more than the total minus the two smallest values.
Comment: Yes, and selecting at random could be directed by an estimate of how many would be needed. If one knew the mean salary, mu, the sum of three would have mean 3*mu and then use the sd() and pnorm() to decide what fraction of samples would suffice.

Sample with constraint, vectorized


Question about differentiating wrt. momentum in Srednicki chapter 14

Question:
I am having a bit of trouble following a simple integral from the book on QFT by Mark Srednicki - free draft can be accessed at http://web.physics.ucsb.edu/~mark/qft.html - and I was hoping you could help me fill some gaps.
The part of interest is chapter 14, pages 111-113, calculating loop contributions to the propagator in $\phi^3$. After he writes the expression for $I(k^2)$ (14.18):
\begin{equation}
I(k^2) = \int_{0}^{1}dx \int\frac{d^d\overline{q}}{(2\pi)^d}\frac{1}{(\overline{q}^2+D)^2}, \tag{14.18}
\end{equation}
he then differentiates twice w.r.t. $k^2$, to arrive at (14.20):
\begin{equation}
I''(k^2) = \int_{0}^{1}dx ~6x^2(1-x)^2 \int\frac{d^d\overline{q}}{(2\pi)^d}\frac{1}{(\overline{q}^2+D)^4}, \tag{14.20}
\end{equation} which I get naively only if I treat the $\overline{q}^2$ in the denominator of the integrand as independent of $k^2$. Does the integral measure affect the computation? $D$ and $\overline{q}^2 = q^2$ are given by:
\begin{equation}
q=l+xk \tag{14.13}
\end{equation}
\begin{equation}
D=x(1-x)k^2+m^2,\tag{14.14}
\end{equation}
where $x$ is a Feynman parameter, $k$ is the momentum of the particle and $l$ is momentum in the loop.
On a slightly related note, below eq. (14.14), when he performs the Wick rotation, he shows anti-clockwise rotation and since poles are at $q_0=\omega-i\epsilon$ and $-\omega+i\epsilon$, the integral value is unchanged if we change the range to $-i\infty$ and $i\infty$. What happens if we close contours over the poles (say we rotate clockwise, or poles were at  $q_0=\omega+i\epsilon$ and $-\omega-i\epsilon$)?
Answer: 1) No. You use translation invariance of the measure to neutralize the explicit $xk$ with a shift of integration variable (which it appears you've already done--note $\bar{q}$ is just a dummy variable in that integral). Therefore you just need to differentiate the $k^2$ dependence in $D$.
2) I'm not exactly sure what you're asking here, but I'll try to provide useful information. You can't rotate clockwise, you'll hit the poles. The point of the Wick rotation is that it takes into account the $i\epsilon$ needed for causality while allowing simple evaluation of the integral (just closing the contour would spoil the four dimensional symmetry, leading to ugly equations). If your question is why the rotation is performed counterclockwise instead of clockwise (that is, why we use $\epsilon$ and $-\epsilon$), I think it's easier to go back to the path integral derivation of the $i\epsilon$ trick. Recall the $i\epsilon$ is inserted so that the path integral projects in the far past and future onto the ground state, so that we produce the appropriate correlation functions for the LSZ formula. Flipping the sign on $\epsilon$ would fail to damp out the excited states, defeating the point of doing the trick in the first place. Alternatively, the $i\epsilon$ in the action acts as a Gaussian convergence factor in the functional integral (it looks like $e^{-\epsilon \int d^d x \phi^2(x)}$) so the sign is essential.
Comment: Thank you for your answers!

1) I am not sure I follow. If I hadn't made the change $d^d l = d^d \overline{q}$, would I then have to worry about differentiating $\overline{q}^2 + D$ instead of only $D$?

2) In the text, it says : "In making this Wick rotation, the contour does not pass over any poles. (The $i\epsilon$'s are needed to make this statement
unambiguous.). Thus the value of the integral is unchanged." How would choosing to go over the poles (rotate the other way around) alter the value of the integral?
Comment: For 1) I haven't looked at the calculation in the book in too much detail, but in these sorts of things you always complete the square after combining denominators. After completing the square you shift the integration variable to knock off the external momentum. For 2) it's a basic fact of complex analysis that you can only deform integration contours in a domain in which the function is holomorphic (no poles). Going the other way will cause you to run into poles, so you can't conclude that the deformation is allowed without changing the value of the integral.


Objective C: Access of primitive data type

Question: I want to access primitive data types like int, Bool in Objective C.
I have created one class in which I declared an integer varriable.
Now in other class i want to access this data and also set the value of it.
As in Objective C setter methods are applicable only for objects and I can't convert int to object.
So how would I be able to access the data ?
Please suggest some approach.
Answer: You can use getters and setters with primitives.
Just use @synthesize, or create your own methods:
- (int)primitiveIvar;
- (void)setPrimitiveIvar:(int)_ivar;

Answer:
As in Objective C setter methods are applicable only for objects and I can't convert int to object.

Where did you get that idea.  You can have Objective-C properties that are primitive types using either properties or normal accessors.
// in the .h file
// intIVar and otherIntIvar are int instance variables

@property (assign) int myIntIVar;
//         ^^^^^^ stops the runtime from sending retain or copy to synth'd ivars
-(int) myOtherIntIVar;
-(void) setMyOtherIntIVar;

// in the .m file

@synthesize myIntIVar = intIVar;

-(int) myOtherIntIVar
{
    return otherIntIVar;
}

-(void) setMyOtherIntIvar: (int) newValue
{
    otherIntIvar = newValue;
}

Answer: chpwn is correct and answers your question directly. This is just additional info.
If you want to convert a primitive value to an object, like for use in an NSArray, you wrap it in an NSNumber like this:
NSNumber *someValue = [NSNumber numberWithInt: 5];

The same thing applies to float, BOOL, char, double and a ton of other primitive types.
To put the object value back into a primitive:
int someInteger = [someValue intValue];

Rule of thumb:
If you're doing lots of math operations, need a number for local use, or need high performance, use primitives.
If you're storing values in the collection classes (NSArray, NSSet, NSDictionary etc…) and need object-like behaviors such as membership tests, predicate filtering, easy saving to disk or plist creation, use NSNumber.
Have a look at the NSNumber class documentation for more info.


How many api calls blocktrail allow per second

Question: How many api calls blocktrail allow per second. On official site mentioned only rate per minute(https://www.blocktrail.com/api/docs#rate_limits). Is this mean that I can make 5 requests per second(or can I do more)?
Answer: I believe it means you could do all 300 requests in 1 second if you really wanted to, and then wait 59 seconds for the next minute. Doesn't matter when you use them within that minute, just that no more than 300 are used per minute.


How to make a multiple columns in an SQL Database table unique

Question: Is it possible to alter a table so that the row as a whole (excluding the IDENTIFIER (ID) ) can only be inserted once in the database?
For example; you have a Start and End timestamp for an Employee, and you want other employees to be able to have the same Start and End value, but you don't want the same Employee to be able to inserted twice the same Start and End value?
Comment: Perhaps you also want to reject overlapping periods for an employee?
Comment: I removed the inconsistent database tags.  Tag only with the database you are really using.
Answer: You can define a unique constraint or index for the rest of the rowsin the column:
<code>alter table t add constraint t_unique_all unique (employee, start, end)
</code>


Easy way to pdf a web report

Question: We are trying to create a web reporting system, with the standard flash chart's, one of the major requirements is that this report must be emailed to customers on a regular schedule as a PDF file.
Does anyone know of either

An easy tool to point at the webpage and pdf it, including flash charts
Another way of doing this?

We have tried sql server reporting in the past and found it to be a little slow and generally the charting is a little unpretty.
Any help is appreciated.
Answer: If your web reporting system is being built using .NET you may want to look into ABCpdf Component for .NET which can be found here. I am not sure if it works with flash charts, as at my work we use charts that are images, but give it a try.
Answer: What is your envirnment like?  You could try using itext or itextsharp to build PDF files.  Crystal Reports is another option, but maintaining separate report files could be a pain in the ass.
Comment: itextsharp is great, although I don't think it can take a snapshot of an existing page.
Comment: I'm sure it can't, but depending on what you are generating, it might be as easy as using the same back-end code to generate the report in a different format.  It really depends on how the application is designed.

Easy way to pdf a web report


Trouble installing react-addons-transition-group

Question: I am having trouble installing the "react-addons-transition-group" using npm. According to the react website:

The addons have moved to separate packages as well: react-addons-clone-with-props, react-addons-create-fragment, react-addons-css-transition-group, react-addons-linked-state-mixin, react-addons-pure-render-mixin, react-addons-shallow-compare, react-addons-transition-group, and react-addons-update, plus ReactDOM.unstable_batchedUpdates in react-dom. - https://facebook.github.io/react/blog/2015/07/03/react-v0.14-beta-1.html

I have tried:
npm install react-addons-transition-group
npm install react-addons-css-transition-group

but I'm getting:
npm ERR! notarget No compatible version found: react-addons-transition-group@'*'
npm ERR! notarget Valid install targets:
npm ERR! notarget ["0.14.0-beta1","0.14.0-beta2","0.14.0-beta3","0.14.0-rc1"]
npm ERR! notarget
npm ERR! notarget This is most likely not a problem with npm itself.
npm ERR! notarget In most cases you or one of your dependencies are requesting
npm ERR! notarget a package version that doesn't exist.

I am using:
"react": "^0.14.0-rc1",
"react-dom": "0.14.0-rc1"

so I am not sure why it is throwing the error. 0.14.0-rc1 is on the list of compatible versions.
My npm version is 2.11.3 and node 0.12.7
Any idea what could be causing this?
Answer: This bug was fixed in firstname.lastname@example.com. Basically, email@example.com fixed a bug wherein pre-releases would satisfy the * semver range. When email@example.com came out with this update, packages like react-addons-transition-group, which only have pre-releases for some reason, could no longer be installed by npm unless you explicitly told npm what version to install.
Issue tracker ticket is npm/npm#8855. A guide for updating npm is available here.


Access 2007: Conditional Formatting not working for control based on lookup value

Question: I have an Access 2007 report with a control based on a lookup field which has a list of values.  The field values are strings:
0. Late
1. Critical
2. Urgent
3. Normal
4. Low
5. Closed
6. Draft/On Hold

In the conditional formatting box, I use:
Field Value Is equal to "0) Late"

and choose a different color background and text color.  This should conditionally change the background and text color of the textbox when it's value matches "0) Late", however instead of showing up as expected, the report simply doesn't print that value.
Access help says "When you apply conditional formatting to a lookup field, the condition must be based on the lookup ID, not the value returned by the lookup field."
I'm not sure what it means by Lookup ID.  Is that a number based on the position in the lookup value list?  I've tried using 1 instead of 0) Late, but that doesn't work either.
Comment: This questions seems more suited to superuser. Do you mean you have included look-up fields in your table? Unless you are using sharepoint, these can only cause you problems such as this.
Answer: The fields in the report were set with background "Transparent"; the backgrounds needed to be set to "Normal" for the fill colors to show up.


How to install resolvconf on raspbian

Question: I noticed that resolvconf is not working correctly, the DNS settings never changed when interfaces or dns servers change, i can't find any trace of resolvconf and can't reinstall it back. anyone knows the package name or something i can do to resolve this.
Comment: I think it's `openresolv` but are you sure you need it? Are you unhappy with network-manager?
Comment: I don't use network manager. i managed to install `openresolv` don't know why apt-get was not finding it before.
Answer: On Raspbian by default resolvconf is managed by openresolv:
pi@raspberrypi:~ $ apt list openresolv
Listing... Done
openresolv/stable,now 3.8.0-1 armhf [installed,automatic]

It is configured in /etc/resolvconf.conf and you can just reinstall it from the repository with:
pi@raspberrypi:~ $ sudo apt install --reinstall openresolv

There is an alternative with systemd-resolvd but I don't know if it works out of the box, means without systemd-networkd. You can try it with:
pi@raspberrypi:~ $ sudo sed -i '1i resolvconf=NO' /etc/resolvconf.conf
pi@raspberrypi:~ $ sudo systemctl enable systemd-resolved.service
pi@raspberrypi:~ $ sudo ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

The first command will disable openresolv without deinstalling it. So you can easily revert by deleting the inserted first line in /etc/resolvconf.conf, disable the service and delete the symbolic link.
Comment: ended up installing this, for some weird reason `apt-get install resolvconf` just didn't work. (tried again later just to check why that package is not found and i was able to install it ... go figure)

How to install resolvconf on raspbian


Wordpress Permalinks not working even with mod_rewrite enabled

Question: I'm trying to set up my local Wordpress instance for development. I've changed the permalinks to http://localhost/localwp/%postname%/ and my .htaccess file was updated successfully:
screenshot of the permalinks screen
.htaccess
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /localwp/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /localwp/index.php [L]
</IfModule>

# END WordPress

Well, this just don't works. I've been searching and found issues about mod_rewrite being disabled, so I made sure mine one was properly enabled on /etc/sysconfig/apache2 (weird path, but its the default at the distro I'm using). Also phpinfo() confirms that the mod is enabled.
Even with mod_rewrite enabled I keep getting 404 when I try to access any post, even using the "View" button on WordPress. e.g: http://localhost/localwp/pagina-exemplo/ (pagina-exemplo is portuguese for example-page, and its created automatically by Wordpress).
If it matters, there is some more details I extracted from phpinfo:
Apache API Version  20120211
Loaded Modules  core mod_so http_core prefork mod_unixd mod_systemd mod_actions mod_alias mod_auth_basic mod_authn_core mod_authn_file mod_authz_host mod_authz_groupfile mod_authz_core mod_authz_user mod_autoindex mod_cgi mod_dir mod_env mod_expires mod_include mod_log_config mod_mime mod_negotiation mod_setenvif mod_ssl mod_socache_shmcb mod_userdir mod_reqtimeout mod_version mod_php7 mod_rewrite

My distro is OpenSuse Tumbleweed 20190428
Answer: I fixed by adding
<Directory /srv/www/htdocs/localwp>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
</Directory>

to my /etc/apache2/httpd.conf file. Where /srv/www/htdocs/localwp is where is located my Wordpress files


Is it okay to use steel strings on a nylon guitar?

Question: I replaced one nylon string (the G string) with a steel string. All the other strings are nylon. Is this okay?
Answer: The short answer is no. The tension of steel strings are way to much for a classical guitar to handle as it generally does not have a truss rod in the neck.
Answer: You'll probably get away with it on a temporary basis, but the tension isn't good for that guitar. Certainly, on a classical guitar, I wouldn't be putting all 6 on. One won't be too detrimental, but also the feel will be different - tighter, thinner - and certainly the sound will be different, so it's inappropriate for many reasons.
Answer: Steel strings are available in a wide range of gauges, which will need different levels of tension to play at any given pitch.  For the most part, one may reduce the tension required to play a certain pitch by using a narrower string, but as metal strings get too loose, pitch stability suffers severely--much more so than with nylon strings.
The tension on a 13-gauge steel string (the "e'" from an heavy-gauge set or a "b" from a lighter set) would be about 9.7lbs.  That's rather light as steel strings go, but probably not unplayable, and it should be safe on a nylon-string guitar (many nylon sets average slightly over 10lbs).  I would not expect such a string to sound very good or offer a good playing experience when used in that fashion, but the tension should be low enough to avoid damaging anything.  Using a 14 gauge string would increase tension to about 11.2lbs; that would probably improve playability, and would probably be safe, but would leave less safety margin against accidental over-tightening.
Comment: I've used .008" top, .010" second for the last 40+yrs, with no pitch problems
Comment: @Tim: A 13ga "g" string would fit right in with a set of 8's for an electric.  Some people like 8's, and on a guitar with a suitable action height they can work just fine.  Nylon guitars often have higher actions, however, and I would expect that a 13ga "g" would be right on the cusp of usability--much better than a 12ga, but noticeably worse than a 14ga.
Answer: Replacing one string with a steel one won't damage the guitar, but the playability of the guitar won't be good. Drive down to a local guitar store and buy a nylon replacement (or even a new full set).
Answer: (I'm sure I answered this before...)
Hey, it's your instrument; the guitar police won't break down your door for putting that string on your instrument. And it isn't like diesel in a gas engine; the damage won't be immediate and cause complete failure. The instrument will be playable until it won't.
But that's not what it's built for, and strings are cheap.


How do you interpret this microbiology/ bacteriology research figure?

Question:
This is a figure from a research article that I am to do a senior presentation for. It is showing  bacterial replication of an enteric bacteria population. The researchers hypothesize that the number of regions near the replication origin will be the highest point (peak) on the graph and the terminus region will be the lowest point because there are least copies of this region in a dividing species. The determine that the ratio of the peak to the trough will reflect the growth rate of the species. That all being said, I don't understand their use of color. The peak has several different colors that do not seem to match any of the examples on the right. Wondering if anyone can help me decipher this? Thanks!
Answer: The short answer is that it looks like the colors are meant to represent different, partial copies of the bacterial genome in the process of being synthesized.
When bacteria replicate, they initiate replication at the origins of their chromosomes.  In fact, these origins can be replicated multiple times before it gets to the "end" of the bacterial chromosome (terminus). Looks like the stacking on the right figure shows this, with the colors just aiding in differentiating the partially replicated chromosomes. The coverage plot on the left shows how this might look based on read coverage from deep sequencing (again the colors just show different, partially replicated, chromosomes).
Answer: I think the figure has the answer. "High copy number near the origin". This is depicted in the graph by the spike at x = 4Mbp. The graph also shows that the number of reads is lowest at a point opposite the ori (2Mbp).
Mbp stands for Mega-base pairs, or 1 million nucleotides. Mbp in the graph refers to a point on the chromosome, with 4Mbp being at '12 oclock', the origin of replication(ori), and 2Mbp being at '6 oclock' opposite the ori. The researchers are measuring the number of DNA fragments(y-axis) that map to a certain position on the chromosome (x-axis). I am slightly color blind, but it seems to me that the colors generally match up. Also note that the reads that fall within the lower-most bracket on the right side of the x-axis span the entire x-axis. This is because these fragments map completely to the chromosome, and indeed they are labelled 'original genome'.
Hope that helps.
Answer: First, it would help if you could provide any more information on the figure (how it was made, is it data based or representative of a model?)
Given that there is little to go on, I can offer my two bits - and I hope it will help you get thinking about it - but ...
It appears to me that these data are a snapshot of the replicating bacterial genomes isolated from many cells at a given timepoint. The right side of the figure shows a model of the (circular) genome in black with a number of smaller fragments of the genome caught partway through the replication process. The left side shows the same fragments stretched out in a linear representation.
The green fragment is the largest as it is nearly finished copying. Other colors show different sized fragments at different points in the copying process. It sounds like the graph is meant to relate the number of different sized fragments to growth rate (assuming you measure fragments from the same number of cells).
So, what does this tell you? (I think it would be helpful for you to think this out yourself form here and determine if you believe this is a good measure or not.)
Comment: Would you agree that "genomic location" (x axis title) shows that they are splitting the circular chromosome into 4 regions?
Comment: Bryant, I don't think they mean to break it into regions. The X - axis is a measurement (in mega-base pairs = millions of bases) according to an arbitrary start point. Replication begins at the origin and extends in both directions. Note the point of symmetry for each of the fragments around the origin.


networking the internet

Question: on my desk top i have modem connected to my computer for a wired connection
i am thinking of buying a wirless linksys router to connect to my modem
i just bought another desktop and i want to use a wireless usb can that be done
Answer: You could. Generally modem (with ethernet) -> router -> computer will work.
Personally i find that internal PCI cards are easier for desktops than USB keys, but there's no reason a USB wireless dongle will not work
Answer: That works but I'd prefer to put a cable if possible... I used 4 different types wireless cards(2) and USB(2) for 2 years and now the 4 pcs are connected with a cable as the performance was terrible, even with good signal and dropping connection a lot (one computer alone was ok). On the same router, I can connect many wireless notebooks very well so the problem was with the wireless adaptors on the desktops and not with the router.
Answer: You can use a USB dongle for wireless on a desktop. I'm doing it right now. USB dongles can sometimes overheat, so I would recommend placing it in the USB port that is closest to the system fan on the case.
The other option is a PCI card. This has the disadvantage that you need to open the case up. However, they are often cheaper.

networking the internet


How do I keep a longer lasting heat?

Question: I'm smoking a turkey for the first time and I've received different tips on how long I should smoke the bird. However, I struggle with getting my heat to stay at 225-250 for more than 2 hours. How do I keep a heat that will last me 8 to 10 hours?
Comment: You keep feeding the smoker
Comment: What kind of smoker? Electric, charcoal? What shape is it?
Answer: I'm going to assume that you are smoking with charcoal as electric smokers don't really have trouble with fluctuating temperature.
Plan on needing to add charcoal every couple of hours during the entire smoking period. I start mine at unwholesome hours of the morning and set alarms to get up and stoke the fire. It is nice if you can stoke the fire without letting out all the heat but that depends on the shape of your smoker.
Keep in mind that you only need to add your smoke producing wood for the first couple of hours. After that all you need is heat, no more smoke flavor will be absorbed.
It is very helpful to use high quality, lump charcoal. Lump charcoal burns longer and produces much less ash. Charcoal briquettes are filled with clay. Not only do they burn out more quickly but they leave mounds of ash that you have to clean out several times during a 10 hour smoking. Around here I can find lump charcoal in large bags at the hardware store and sometimes at Costco for much cheaper.
Another alternative:
If you aren't a purist who needs to be able to say that the turkey was cooked only with coal, you can always finish it in the oven. I've read that meat will soak up all the flavor that it is going to in the first hour and that matches my experience. After that it is just slow cooking which is much more conveniently done in a low oven.
Comment: When you consider that you get around 2x the heat from lump charcoal as compared to the same weight of briquettes, lump often ends up being more economical.  (longer burning, plus burns hotter)
Comment: I appreciate all of the insight! I have a long barrel shaped smoker! I'll try this turkey for the first time this year with the advice you all have given me!!

How do I keep a longer lasting heat?


Which to use Jquery or Ajax

Question: In my project  i have to create an Accordion.which is better to use Jquery or Ajax
Comment: I think first you have to learn what is the difference between [Ajax](http://en.wikipedia.org/wiki/Ajax_%28programming%29) and  [jQuery](http://en.wikipedia.org/wiki/Jquery). Basically Ajax is some kind of technique whereas jQuery is a JavaScript framework that makes it easier to use Ajax (among other things).
Answer: AJAX is for server-side requests, to get or send new data for your page (without a full page reload), it's an alltogether different concept.
For the accordion, I think you're looking for the jQuery UI accordion, though there are many options out there.
Answer: That's a bit like asking "What should I use to get to work today? A car or an accelerator pedal?"
AJAX is a general term that refers to the techniques that make use of client-side scripting (e.g. JavaScript) to communicate with the server between page-loads.
jQuery is a framework (a set of libraries and tools) that make writing JavaScript simpler and easier. It includes facilities for using AJAX.
Comment: Watch out @Will, @sundowatch might tell you that jQuery is a library if you're not careful.
Answer: Hmmm, Apples, Hammers, or music?  how to decide?
Comment: Hammers, then you can make every problem a nail.
Comment: Apples, hammers and music all suck! You want horses!
Answer: AJAX, or Asynchronous Javascript and XML, is an umbrella term for the technologies and methodologies involved in loading data from the server without a page request.
jQuery is a Javascript library.
Javascript is a client side scripting language.
As @Nick said, the jQuery UI accordion plugin is a good choice for the accordion.

Which to use Jquery or Ajax


How is heat represented on a quantum level?

Question: Heat is just a form of kinetic energy for molecules, because as temperature rises, the heated molecules are "shake" and "vibrate" more and more. But how does that show up on a quantum scale? What element actually carries the kinetic energy: the heated molecule as a whole, its atoms, the nuclei, or the electrons' orbits? (Maybe even the quarks found in the nuclei?). Or is it that the shaking described is only an analogy for a notion of energy that is more difficult to grasp as their is no real physical movement in the heated object?
Comment: Look at KMS states. Also remember what you've kept in your algebra of observables.
Comment: Two comments. (1) "**Heat** is just a form of **kinetic energy** for molecules":  this is not correct. The word **heat** always refers to a specifical process, "*the heat exchanced in the process is...*", and is not "stored" in the thermal motion of the molecules. I think that by "heat" you really mean "internal energy".
Comment: (2) This question is more about *statistical mechanics* than *thermodynamics*: you're asking how does the macroscopic quantity "internal energy" (or maybe "temperature", but not "heat") relate to the microscopic (quantum) structure of the system? And that's precisely what *(quantum) statistical mechanics* is all about. Therefore, I suggest you to add the tag ;-)
Answer: Heat energy, at a microscopic level, is stored in the degrees of freedom of atoms and molecules. These degrees of freedom are translational, rotational and vibrational. They all store different amounts of energy, depending on the geometry of the atom.
Translational degrees of freedom are the atom or molecule moving around in space, and there are always 3 for the 3 dimensions of space. The rotational and vibrational modes come from the geometry of the atom/molecule.
From quantum mechanics, we get the idea that energy stored in rotational and vibrational (and translational, if confined) modes must come in quantised packets, with a minimum size. This size depends on the form of a certain mode. For single atoms, the moment of inertia and the energy of rotation is very small. The quantum of energy that must be added to excite the rotational modes is large, and so these do not contribute to heat storage until very high temperatures.
Molecules have much higher moments of inertia around certain axes. For example, O2 has high moment of inertia around the two axes perpendicular to its bond axis and a low moment of inertia around its bond axis. It therefore stores heat energy in those two and they contribute to the heat capacity of O2.
Vibrational modes store much more energy than translational or rotational modes, and are active only at higher temperatures.
This is basically what heat is at a microscopic level. Quantum mechanics gives us that the energy stored in the modes must be quantised.
Answer: The equipartition theorem says that all modes of excitation carry heat. There may be some modes which are too energetic to be excited at a given temperature, but the remaining modes are all excited. In overly simple terms, everything that can shake will shake.
Answer: It is somehow an open subject of research. No way through just subdividing you end linking quantum world to classical one. At quantum level, different classical processes reading to a particular concept, always rely on just already determined positions and energy of a system. When one goes to systems with very low entropy we tend to lose track of measurable energies whereas high energy systems are  also source of different other particles. We then find different divisions inside physics itself, where, it is not possible to reconcile small to big or low to high energy. Always different sub-domains are to be made for different scenarios. The main question to ask some times is, could be their parameters other than just scientific limitations in understanding, which kind of block different levels of understanding to combine information in a correct way, which can simply, show clearly how exits to a particular understanding are hold up by other than just personal perceptions of things.
Answer: phonons  are called quantum of lattice vibrations. Just as photons are quanta of EM radiations.In solids lattice vibrate due to heat. The quantum of lattice vibration is called a phonon. It is planck constant X frequency just as you have for photons. The heat capacity of solids for example and the thermal conductivity are explained using this phonon concept. –
Comment: I have edited my answer in view of your comments
Comment: Could you please elaborate? What exactly are quantum vibrations?
Comment: This answer (insofar as I understand it) is incorrect. Heat isn't carried solely by phonons, although they do contribute to it.
Comment: He wants to know the about heat at quantum scale. That's the basic question to be answered.
Answer: heat is not kinetic or something,heat must be emergence and to be a question how the quantums could connect with others without emergence and out side of the consequence,then the time and anything do not growing by cause and consequence theory.then the paradox occur,i absolutely don't understand it.


Shade Forest Ground Cover

Question: I have an area on my property in New Hampshire that borders my lawn. It's mostly pretty heavy shade from maples. It also gets pretty moist at times throughout the year. Right now especially on the edge a variety of weeds that grow pretty tall sprout up every year but my plan is to keep those down by brush hogging them 2-3 times a year to keep the height down. Any suggestions of a variety of grass or other ground cover the would grow well in these conditions?
Comment: Are you looking for native or non-native suggestions? Do you want the groundcover to out-compete the weeds at the edge of the woods? Are the woods remnants of native forest or trees like Norway maple?
Comment: @Jurp I'd have a slight preference for native but either is fine. Looking for a ground cover to stabilize the soil. I would like it to out complete the weeds but whereas I plan to mow it a few times a year I'm hoping that reduces their number over time too. It also doesn't need to be a single mono-culture. Just looking for something low maintenance to keep it more like a grassy forest. Mostly looking to keep a view line open through the woods. The trees are mostly Silver Maple, Sugar Maple, Black Cherry, Eastern Cottonwood, and I think there is one small Ash I'm letting grow up.
Answer: Sounds like a nice woods. The problem I think is that grasses don't like shade (with one exception, noted below), and there aren't a lot of natives that work well as weed-reducing groundcovers except, perhaps, some of the more rampant ferns such as:

Ostrich Fern (Matteuccia struthiopteris). Ostrich Ferns will run underground and can become an effective groundcover over a few years.

Other non-rampant native ferns that might work because they're tall and will form large clumps over many years are:

Interrupted Fern (Osmunda claytoniana)
Cinnamon Fern (Osmundastrum cinnamomeum)
Regal Fern (Osmunda regalis var. spectabilis)
Christmas Fern (Polystichum acrostichroides.

The issues with those are slow in-fill and relatively high cost because you can only buy plants, not seed (Ostrich Fern will be the least expensive). Except for Christmas Fern, they top out at 3+ feet high.
If you do have some drier areas, then you could look at Robin's Plantain/Robin-plantain (Erigeron pulchellus, which is an odd yet effective groundcover in preventing weed seeds from sprouting (it works best if the land is clear when it's planted). It forms rosettes that spread just below the ground's surface, and blooms in May (zone 5). One plant will cover about 9 sq ft in 5 years, so not the fastest groundcover.
Other natives that could (slowly) work are:

Partridgeberry (Mitchella repens)
Bunchberry (Cornus canadensis)

There are many faster non-native groundcovers, but I personally don't like them in our native woods, so won't recommend any except Japanese Forest Grass (Hakonachloa macra), because you mentioned a grassy view and this grass isn't too nasty in the wild. One plant will form a nice 3 ft by 2 ft drift in a few years, and will slowly spread from there. I would get the green variety (the actual species) rather than the gold and gold variegated ones solely because it would blend better into the landscape, IMO. The major drawback with this option is cost - the plants are not inexpensive.
You may find this site (Adirondacks Forever Wild) useful in picking plants (it's referenced above as well).

Shade Forest Ground Cover


Verb for adding to inventory

Question: What verb can I use for, for example when a real estate agent goes to a house and adds that real estate to his inventory with noting some specs, address etc.
Comment: Well, if it were something other than an house he would be "stockpiling".
Answer: What you are probably looking for is "to list [a house]".  For example:

The real estate agent finished taking pictures yesterday, and is going to list my house tomorrow.
Comment: It sounds logical
Comment: @EralpB Are you looking for something specifically related to real estate? Note that *list* here refers to representing the owner in finding a buyer for a home, not simply "make a list of houses with details for each". If the latter is more like what you are thinking of, *cataloguing* as suggested by Pharap is a better choice.
Comment: @EralpB Perhaps that would be better stated, *list* here means *publish a list*, not simply *compile a list*.
Answer: May not be quite what you're looking for, but you could say he is Cataloguing the house. The verb Catalogue both implies collecting information and that the item in question is one of many.
Answer: Interesting question. I'm not sure if "listing" is appropriate, since in your example he merely finalized an agreement or made a decision to try to sell it; "listing" it or "putting it on the market" seems like a later and separate act, requiring preparation and time. But I suppose that by "adding it to their inventory," a realtor/office could either be agreeing to the sale, or actually beginning to market it to the public
In your example about the realtor himself.....I'd say it's more a type of possession, though since the house does not belong to him in any sense, what he possesses is the "deal," or the right/opportunity to use it in business
In one sense he's claiming it (or the rights to its sale), though I think this word would only be used to emphasize a kind of personal victory over others attempting the same thing ("we all wanted a chance at the Andrews place, but Jim got there first and claimed it/snatched it up/grabbed it").
It might be better to say that he acquired the property. It has a similar 'possessive' meaning, but it is more neutral and less "grabby" sounding than claim. It's also used to describe the action of business entities, so would be very appropriate if saying that his firm "acqquired" the house/deal.
If we want to try something other than the possessive cluster, we could think of it as a job. "He talked to the owners and decided to take on the sale."
In legal papers, this act seems to be most often referred to as the agreement between seller and realtor, at which point he is designated as their agent in the matter.
I suppose these would all work, in certain contexts. I don't think there's a specialized term for the initial process and decision between the seller and realtor, like the term "listing" for when he tries to find a buyer.
Answer: Each and every area of specialisation (real estate, shipping, air freight) tends to have their own local special words or phrase to describe the aggregation of another item to the grouping.
It can be very frustrating trying to identify each of the special words, or worse, choosing a suitable well understood phrase for such packaging.
My personal example is of the software source control programme Git which can't agree (among many options) on the right word for the 'list' [index, staging area, manifest, cache, ...] of items being made ready.
Here in UK, houses are  'Listed' for sale by Estate Agents.
Answer: If it's retail, then I'd say to "stock" something.
Answer: To take note of. This may imply pen and paper depending on the context, but it can also just mean to make a mental note.
http://idioms.thefreedictionary.com/take+note+of

Verb for adding to inventory


3-D looking graphic - What software can be used to create such?

Question: Is there a term for such an image, and what software is used to create a graphic like the following image, for example? It looks like some kind of vector image built from basic shapes.
Comment: Ok, so while I personally wouldnt have much problem drawing that image. It  does underline a issue, ive spent the last 10 years specializing in this kind of things for fun. A better question would be to ask what is the shortest path to acieving this. And unfortunately that answer is use a cad application then color in illustrator or inkscape.
Comment: Affinity Designer (specific vector design app) has an entire suite of iso drawing tools - I used to do these in illustrator, but it was a fair amount of work; in Designer, it's close to trivial.
Answer: The view is called isometric projection (or simply isometric).
There are tons of tutorials online on how to draw such images.
The style is pretty minimal. It could probably be called Flat Design or perhaps Flat Design 2.0 because of the use of gradients.
It can be drawn in any vector drawing application with basic tools. Commonly people would use something like Adobe Illustrator (subscription software) or Inkscape (free).


Is there a way to find recently updated passwords in KeePass?

Question: I'd like to find recently changed passwords in KeePass so that I can copy/paste them into another KeePass repository. I see that the date updated is stored as the version in the History tab, but I don't see a way to sort entries by this value. I'm thinking that this isn't possible.
Answer: KeePass 2.xx

menu View > Grouping by Entry List > Off
menu View > Show Entries of Subgroups → set checked
OR to view all entries one time only, go menu View > Show all
menu View > Configure Columns... → place check mark at Last Modification Time and confirm
click the root item of your KeePass folder tree
click header of Last Modification Time column to get all your passwords sorted by date/time

You can now see entries from your entire database sorted by Last Modification Time.
Comment: Awesome. On mine (v. 2.32 on Ubuntu 16.04), the "Show all" is not under "View", rather it is "Edit > Show All Entries" - to save anyone else those milliseconds it takes to look in the other menus.
Answer: KeePass 2.42
Main menu Find > Last Modified Entries....
The most recent modifications are on top. It looks like there's the whole log of changes in the opened database since it has been created. In my case, it goes back to the year 2006.
Answer: An easier solution is:

Click "EDIT"
Click "SHOW ENTRIES"
Finally click "LAST MODIFIED ENTRIES"
Comment: Can you elaborate on this a little more?
Comment: The "LAST MODIFIED ENTRIES" feature has been recently added to KeePass, so the procedure above can be used to get all the "passwords recently updated". Just click Edit --> Show Entries --> Last modified entries to get the list of entries with references to the "Last update date". You'll get a nice dialog with the following information: group | Entry name | Username | Date of last update
Answer: Take a look at https://keepass.info/help/v2/sync.html
You may be able to automate synchronisation.
Answer: Alternatively You can use KeePass build-in synchronization. To manually synchronize with file go to menu File > Synchronize > Synchronize with File. More about synchronization: http://keepass.info/help/v2/sync.html
Comment: Maybe you can explain how this can be used to find recently updated passwords (what was asked).
Comment: Question was about way how-to manually copy-paste new passwords from one repository to another. There is future that allow synchronise few repositories in several ways, or simply to have passwords synchronised automatically without need of manual copying.
Answer: KeePass 1.xx
The other answers here appeared to be for KeePass version 2. This answer should work for Version 1 on Windows.
I am not sure why this works, but here is what I did:

Ensure the column for "last modification time" is enabled
Somewhere in the left (groups) column, right click
Click Rearrange > Sort Group List
Voila, the right side is sorted by last modification date

(again, this doesn't make much sense, but it works... and you still cannot click the column header to reverse sort it... strange.)
UPDATE:
This appears to only show the second-to-latest update at the top - again, not sure why. But if your top entry is an entry in the "backup" group, it should still give you a good idea what the last thing changed was... i.e. go look at the current entry for the one listed as last changed in the top "backup" entry.