125 amp sub panel cable suggestions

Question: We will be installing a 125amp sub panel in our pole barn which is about 115 feet from the main panel.  We will use 125amp breaker in the main panel and run conduit the entire run. From what I have read we can use 2/0 aluminum.  Was looking at using 2/0 2/0 1 4 MHF.  Is there a better choice that we should be using?  Thanks for the input.
Comment: We will be using this space as an arcade area, 10-15 arcade games, 4 TVs for the gaming cabinets and another -10 tvs for sports. 36k mini split, frozen drink machine and a popcorn machine. Various other items. 23 led canned lights.
Comment: Make sure you get a **really big** panel. You will *likely* have to have almost every circuit on AFCI, GFCI or both. And if you can easily do so (which you should be able to do when finishing the inside of a barn) put in a lot of separate circuits. It might be that you put in a 200A subpanel *because that's what gets you a good deal on a big panel and that's OK - the breaker in the main subpanel has to match the subpanel feed wires but the main breaker (which is technically there to be a disconnect) in the subpanel can be larger.
Comment: Sounds like a fun place! And actually does sound in the range of 100 A if everything is going at once. The more typical barn usage we see in questions is a shop with lights + a few tools.
Comment: 1200 sq foot space.
Comment: Yes we figured we would go with 125 amp breaker, though it might be overkill better to have it if we need it.
Comment: How many square feet is this space?
Answer: There are 2 separate questions that need to be split off. It's very similar to the posted speed limits on a road vs. the speed rating on your tires.
The size of the feeder supplying the sub panel.
This needs to correspond to the actual or likely usage you will have at the sub panel.  For instance if you have a 12,000 VA of EV charger and 3600 VA of other loads, that's 15,600 VA or 65 amps.  So you would need a feeder and supply breaker ready for at least 65 amps.
The ampacity limit of the sub panel.
This only needs to be greater or equal to the above number.
The main consideration here is on sub panel size should be to get plenty of breaker spaces.  The #1 problem we see with subpanels is "I need to add a circuit, but my panel is out of breaker spaces".  Well, that problem was caused by bad choices earlier, which in this case is "Right now!" Spaces are cheap.  Aim to finish the project with at least 50% of spaces unused.
This may result in a panel whose amps are quite a bit larger than the first number.  That is fine.
Your panel and wire size
The breaker must protect the wire based on its amp limits. However, if that breaker is not made, you round up.
So at your size, it's a labeling game.  If you are ferociously committed to calling this a "125A" feeder, then you must use 2/0 aluminum wire (since 1/0 is only good for 120A).
However if you are willing to label this a "120A" feeder, you may use 120A wire (1/0).  Since 120A breakers are not made, you use a 125A breaker.  You must pinkie-swear never to plan to draw more than 120A.
125A is the largest breaker of reasonable size and availability, so it's a good choice.
Comment: I'd like to see the _pinkie-swear_ reference in the NEC. :D ROFL
Answer: You have plenty of feeder space, don't worry
Calculating the arcade cabinets and TVs at 180VA/unit (the miscellaneous receptacles number from NEC 220.14(L), which isn't too far off for arcade cabinets from the quick Google search I did, and a pretty generous allowance for modern LCD TVs) and adding 1500VA for the concession machines gives us 6900VA of plug load. Atop that, we add the 36kBTU minisplit: using an 18.5 SEER LG single-zone heat pump as a reference, we wind up with 23A * 230V * 1.25 (for being the largest motor in the space) = 6613VA for the minisplit.  Finally, the lights are calculated based on standard square footage lighting loads; treating this space as a club of some sort, we get 2VA/ft² or 2400VA for your 1200ft² space.
Adding this all up and dividing by 240V, since we don't have enough receptacle load for demand factors, gives us 15913VA, or around 66-67A at 240VAC.  This means that a 125A feeder is quite ample for the task at hand, with no shortage of expansion room if more is needed in this occupancy, and your 2/0-2/0-1-4 MHF will have no trouble handling what you have in store.
You'll want plenty of panel space, though!
However, you'll want plenty of loadcenter spaces in this setup, since your feeder is indeed good for 150A (although with some caution since your neutral is limited to 100A of maximum imbalance), and loadcenter spaces generally go fast!  I'd recommend a 30-space or 32-space, 125A, main breaker loadcenter as a minimum here; if you want to go to a 40-space or 42-space, 200A, main breaker loadcenter instead, that may be worthwhile given the cost differential is only about $100.
Keep in mind that you'll need to fit accessory grounding bars to the load center, as well as pulling the loadcenter's bonding screw and running a 6AWG copper grounding electrode conductor to the grounding rods or grounding electrode for the barn.  Note that unlike on a main panel, this grounding electrode conductor lands on the grounding bar; if you're wondering how it can get into the breaker box to begin with, that's the job of a part known colloquially as a "Kenny clamp" that is used to clamp single wires to knockouts.
Finally, you'll need a few gadgets that you don't normally put in a house
Finally, we'll need to power a few things that don't normally go into houses, as this really is a small assembly space, especially given its size.  The closest thing to what you have in IBC 1004.5 is what they consider a "gaming floor" (their examples are casino-based, but I suspect arcade gaming counts all the same since they mention slot machines in the Code text), which is 11 gross ft²/occupant, or an occupant load of 109 people for your 1200ft² barn.  This is enough to put you well outside of the 50-person rule that allows small assembly occupancies to be treated the same as business occupancies (office type spaces) by the IBC.
Going into more detail, your occupancy is somewhere between an A-2 (food/beverage consumption) and an A-3 (miscellaneous recreational) occupancy in the IBC system, given that food consumption and preparation are incidental to the function of the occupancy.  Either way, you'll need at least two ways out of the barn that are outswing doors with panic hardware and combination exit sign/"bugeye" emergency light fixtures, as well as perhaps a couple more combination emergency light fixtures to serve as directional exit signs, or simple "bugeyes" to provide additional emergency egress lighting, depending on how much the space is divided up.  (Don't worry about the pricetag -- combination exit sign/emergency light fixtures are standard, off-the-shelf parts that a lighting supplier can get you for $50-odd a piece, and the orange borg has panic hardware for $100 a unit, which can be fitted to a standard 30" exterior door hung outswing with jamb pin screws in the hinges.)
The other big question is whether you'll need to fit fire sprinklers or not; this is something you will need to talk with your AHJ (local building official and/or insurer) about, since it depends on whether they see your barncade as an A-2 occupancy (like a casino or nightclub with a kitchen and/or full service bar) or an A-3 occupancy (like a pool hall or dance hall with no food or drink service).  This also determines whether you'll need to install a fire alarm panel, as sprinklers in a non-dwelling need an alarm panel to supervise the system (aka let folks know that some clown shut the sprinklers off).
Answer: 2/0 can handle 150 amps when less than 200 feet. I hate to run at max and considering conductor count, underground and long length, I like your decision to use 125 amps.
I am not sure where you are getting the 2/0,2/0,1,4 feeder wire because the new wire is 2/0,2/0,2/0,1. Considering your wire sizing and application, there is nothing wrong with the old wire you spoke of assuming that you do not intend to get an inspection.
Don't forget to keep neutral separated from ground. If the garage is disconnected, remember to add couple of ground rods out by the new sub.
Comment: There are so many cable types I was sure what to go with. SER I read shouldn't be put underground, so we landed on the MHF.  The big box stores have limited supply on a lot of stuff so we were looking at the online stores which would have both the 2/0 2/0 1 4 and the 2/0 2/0 2/0 1. The ground rods are on the list.
Comment: 2/0-2/0-1-4 is a standard MHF size -- in fact, the supplier I usually check doesn't have 2/0-2/0-2/0-1 in MHF
Comment: @Bryhud try real electrical supply houses. Box stores only sell the popular stuff, they're not there to be an everything store, they mercilessly cut out anything the computer says doesn't sell well.  E.G. they'll sell a conduit system, sell right ells, but not left ell's because they don't sell enough.   Better to find an electrical supply you like and buy all you can from them.  Also often cheaper!
Comment: The 2/0-2/0-1-4 will be fine. I looked up the wire and found 2/0-2/0-2/0-1 and assumed that it is a new code. Electrical codes are getting completely out of control. There is nothing wrong with 2/0-2/0-1-4.

125 amp sub panel cable suggestions


Dangerous to use water heater which activates circuit breaker?

Question: I have diagnosed an error in my water heater. A control board is defunct and needs replacement. Unfortunately it is winter now and the replacement delivery will take a week or longer. The water heater still functions properly but trips the circuit breaker of one phase occasionally. Is it still safe to use until the replacement arrives?
Comment: What make and model is said heater?
Comment: It's this model.Unfortunately the specification and manual are only available in german.https://www.aeg-haustechnik.de/de/home/produkte-loesungen/warmwassergeraete/wandspeicher/geschlossener_wandspeicherdemcomfortel30bis150liter/dem_80_comfort_el/technische-daten.product.pdf
https://www.aeg-haustechnik.de/content/dam/aeg/cdbassets/current/bedienungs-_u_installationsanleitungen/DEM_30-150_Comfort_EL_variowall__6b8a7305-a38a-4383-898c-1869f2fd77c2.pdf
Answer: It is probably "safe". However, a problem which results in an overcurrent trip on one breaker might be causing damage to the related equipment (heating element, relays, etc.) in a way that doing so repeatedly (even for a week) might result in other parts of the heater breaking. Nearly impossible to tell, especially over the internet, as there are a lot of variables involved.
If it is possible to run the heater with that phase (leg) off, then that may be a temporary solution. However, depending on design that may not work at all, or it may result in the other heating elements running at a higher duty-cycle and cause other problems.
This is one of those situations where a few extra $ for fast shipping may be worth it.
Comment: Thanks for your reply. Problem is that the phase which is tripping is L1 (first phase) so it cannot be replaced because all the controls are powered by L1
Comment: Unfortunately I am unable to download the German link, which I speak, read and write. A grounded element will cause the reset button to pop and the breaker to shut off the power. If heater is electric, check the elements for continuity and replace.i have ignored this issue on my own hot water heater and it has not adversely affected any adjacent breakers, fwiw.
Comment: @Hndygrl Thx for the input. Strange the links work fine for me. The control board has some black spots (smut), so I ordered a new one..It's also annoying if the circuit breaker trips more than once a month..
Comment: Tell me about it! I am troubleshooting mine now!


Strongswan crypto

Question: How does StrongSwan enable different crypto libraries?
Answer: By default, strongSwan uses its own implementations for cryptographic algorithms. These are provided by e.g. the aes, sha1 and sha2 plugins. The default implementation for public key cryptography (RSA, DH) is provided by the gmp plugin, which relies on libgmp.
Enabling the openssl or gcrypt plugins, while not-building or not-loading the default plugins, allows to replace the default implementations with those provided by the respective libraries (libcrypto/OpenSSL or libgcrypt).  The actual features provided by these plugins depend on how the underlying library was built, for instance, if OpenSSL was built with support for Elliptic Curve Cryptography (ECDSA, ECDH).
You can check which features each plugin provides with ipsec listplugins after starting the IKE daemon with ipsec start. The currently used implementation for each cryptographic primitive can be listed with ipsec listalgs (this depends on the order in which plugins are loaded, the first implementation will be used).
It's important to note that these plugins are only used for the key exchange (IKE, ike keyword in ipsec.conf). The ESP traffic is handled directly by the operating system's IPsec stack, for instance, the Linux kernel, which provides its own modularized crypto framework.
The parameters you may use in ipsec.conf depend only on the availability of a specific algorithm, either provided by any of the plugins (IKE) or by the operating system's kernel (ESP).  All supported algorithms/keywords and their availability in plugins and (Linux) kernel can be found on the strongSwan wiki.
Comment: It does for some operations. For instance, strongSwan's _gmp_ plugin uses [mpz_powm_sec](http://gmplib.org/manual/Integer-Exponentiation.html), if available, when signing with RSA or computing DH secrets.
Comment: Does GMP support constant time arithmetic? General purpose big integer libraries usually don't, leading to side-channel attacks when used in cryptography.
Answer: Unless you've got a pressing reason to, I'd suggest that if you're trying to configure something like an IPSEC tunnel for the first time, stick to default values as much as possible, it'll make the process easier.
That said if you need to use gcrypt with strongswan, they have configuration examples for that scenario on their site here

Strongswan crypto


Vayikra 14:19 differences in trope

Question: וְכִפֶּ֕ר עַל־הַמִּטַּהֵ֖ר מִטֻּמְאָת֑וֹ  I am having trouble truly understanding the difference of meaning using the different trope (zakef gadol, tipcha, etnachtah OR mercha tipcha etnachtah). I understand how to chant those signs, but I need more help in interpreting the difference in meaning.  Vayikra 14:19
Comment: https://judaism.stackexchange.com/q/82068/11532
Comment: Question would be how tightly the words "vechiper" and "al haMeetaher" are grouped.
Comment: Please compare the trup trees for Vayikra 14:19:
http://www.mivami.org/trup/Leviticus%2014:19
and Vayikra 14:53 http://www.mivami.org/trup/Leviticus%2014:53
Answer: There are four things to keep in mind.

First, there are conjunctive and disjunctive trup symbols. Disjunctive divide up a phrase at the point they appear while conjunctive joins. Zakef gadol, tipcha and etnachtah are all disjunctive, usually. Mercha is conjunctive.

If a subphrase contains three words, it needs to be subdivided by a disjunctive trup.

However, as William Wickes writes, sometimes a phrase with only two words, ending in either etnachta (mid-pasuk) or silluq (end-pasuk) will have a foretone of tipcha, for what are essentially musical concerns. Such a tipcha doesn't divide.

Thus, if we consider what Sefaria has for Vayikra 14:19, matching the Leningrad Code:
וְכִפֶּ֕ר עַל־הַמִּטַּהֵ֖ר מִטֻּמְאָת֑וֹ is divided as:
וְכִפֶּ֕ר || עַל־הַמִּטַּהֵ֖ר מִטֻּמְאָת֑וֹ
and atone || for the one being purified of his defilement
And the tipcha you see on al-hamitaher would be in a two-word phrase, and is simply musical.
That was pasuk 19. As you mention (in the comment), Koren and Tikkun Simanim has mercha in place of zakef. That would make it:
וְכִפֶּ֥ר עַל־הַמִּטַּהֵ֖ר מִטֻּמְאָת֑וֹ
Then, there would be no pause on the first word, and the first and second would join together. And, even according to Wickes, the tipcha would function in its usual role of disjunctive accent. Thus:
וְכִפֶּר עַל־הַמִּטַּהֵר || מִטֻּמְאָתוֹ
and atone for the one being purified || of his defilement
Thus, in the former, the action is "atone", and the object is "the one being purified of his defilement". In the latter, the action is "atoning from defilement" while the object is "the one being purified". The meaning of these two actions may be different.
Please compare also the trup trees for Vayikra 14:19 and (although it isn't the verse in question) Vayikra 14:53. Though that doesn't treat the tipcha in a two word phrase as I described, it does give secondary treatment to tipcha over zakef.
Comment: Koren has mercha in pasuk 19.  The Tikkun Simanim does too as the default, but they say on the side that the Keter has zakef gadol.
Comment: Thanks. I'll edit that in
Comment: I don't think that the Simanim Tikkun is saying that the Keter (i.e., the AC) has *zaqef gadol*. Whether you agree with me comes down to what you think the phrase ובתאג׳ תורה קדומה means. I think it means "and in an ancient taj Torah," which to me means an ancient Masoretic Torah manuscript.
Comment: [continuing] Yes, *taj* is just Arabic for crown, which is *keter* in Hebrew, but the two words have different usage, and my impression is that when people mean the AC, they use *keter* not *taj*. Anyway, we lack the definite article. I.e., I would translate this is "a taj" not "the Taj/Keter."  We don't know which manuscript they are referring to since they are vague. Perhaps they don't get into specifics because they view their audience as primarily non-academic.

Vayikra 14:19 differences in trope


NSSet implementation

Question: This question is just out of curiosity but, how is NSSet implemented? What data structure is behind it and what are the access times for adding and removing elements? If I had to guess, I'd say it was some sort of hashtable/dictionary data structure, but in that case why differentiate between NSSet and NSMutableSet?
Answer: Well, as Bavarious pointed out in a comment, Apple's actual CoreFoundation source is open and available for your perusal too. NSSet is implemented on top of CFSet, whose code is generated (as is that of CFDictionary) from a hash table template, using CFBasicHash to do the work.
The difference between mutablility and immutability seems to be the matter of a flag in the structure (line 91 of CFBasicHash.h), and from my reading so far just affects calls to functions such as CFBasicHashAddValue; there's a simple check for the mutability. It seems likely, however, that Cobbal is right about the copy/retain behavior between the two (I just haven't read that far yet).
PREVIOUSLY:
I find it interesting and educational occasionally to peruse the GNUstep sources when I'm wondering about implementation details. They are, of course, not at all guaranteed to be implemented the way that Apple did it, but they can be helpful in some cases. Their version of Foundation: http://gnu.ethz.ch/debian/gnustep/gnustep-base-1.20.0/Headers/Foundation/ (I hope that's the most recent version. If not, someone please correct me.)
Comment: Core Foundation collections, upon which Foundation collections are built, are [open source](http://opensource.apple.com/source/CF/CF-550.42/). CFSet.c is machine-generated from a hash table template. Sets seem to be implemented as hashes.
Comment: @Bavarious: Amazing! Thanks. You should turn that into a proper answer so it gets proper attention.
Comment: Nah; feel free to edit your answer and include that bit, and maybe expand on mutable vs. immutable.
Comment: @Bavarious: Thanks, done. It's quite a read; probably keep me up late tonight. Please let me know if I misspoke in my answer.
Answer: To answer the second half of your question: one benefit of having a non-mutable version is that it allows for a very fast copy method that simply calls retain.
Comment: Another benefit of immutability: you know that you can't accidentally (or someone else purposefully) change the contents of the collection.
Answer: I find this link to be an interesting answer to your question. Apple's data structures (NSArray, NSSet, NSDictionary, etc.) are not implemented in a straightforward and "standard way." In most cases, they perform in the same way any other set would perform, but overall, they optimize automatically for the best performance. So, in truth, it's rather difficult to say. While Apple provides documentation on the efficiency of arrays in CFArray.h (equivalent for NSArrays), it offers no such documentation on the efficiency of sets, though you're free to poke around /System/Library/Frameworks/CoreFoundation.framework/Headers/ to look through other data structure implementations.
In addition, there has to be a distinction between a set and its mutable counterpart, just as there is a distinction between NSString and NSMutableString, NSArray and NSMutableArray, and NSDictionary and NSMutableDictionary (among others). For data structures and strings (and few other classes), Apple offers 'readonly' versions of classes to retain generality, along with standard 'mutable' counterparts for manipulation. It's simply Apple's standard practice.

NSSet implementation


What is the installation size of a clean build of 4.2?

Question: This is a pretty simple question, but one that I have not been able to find the answer to.  How much disk/storage space does an installation of Jelly Bean (bonus points for other versions) take up?  I am not looking for a super-accurate answer, as installation size varies from device to device, but more of a ballpark answer in the gigabyte/gibibyte range, such as 1.7 GB.  Or does Android's size vary drastically from device to device?
Comment: I'm curious about this, too.  My phone is advertised with "4 GB of internal storage" but the Settings > Storage screen shows a total of 1.27 GB.
Answer: Well, to put this another way:
For Gingerbread, storage space weighs around 95Mb, give or take, including Google Apps, source code 6.5GB, compilation taking up approx 14GB space.
Android's storage space for ICS, weighs around 160Mb, give or take, including Google Apps, source code 9.5GB, compilation - takes up approx 20GB space.
As to JB, have not yet built it, but source code is 12.5GB, compilation takes up around 25GB space, various official JB images hovers around 200Mb mark.
The above ball-park figures above, reflects from GB, ICS and JB. As for the future versions of Android, only time will tell how much more space will be taken up, it will increase, no doubt!
As for the final image build output, this would be dependent on handset, as ROM developers/manufacturers love to add their own bits, hence the inclusion of the "give or take" in the above sentences, not to mention carrier bloat-ware so the mileage will vary.
Comment: I don't quite understand two statements: "compilation takes up around _x_ GB" and "including Google Apps".  I can understand that the source code would be bound to be one or two orders of magnitude greater than the compiled binaries, but what do you mean by "compilation takes up around _x_ GB"?  Do you mean that the total space required to compile Android takes up _x_ gigabytes on the host environment?  And by "storage space weighs around 95Mb, give or take, including Google Apps, source code 6.5GB" do you mean **Google Apps + Gingerbread = ~95MB**, or **Google Apps + source = ~6.5GB**?
Comment: What I meant was the compiling of the source code takes up that storage space, albeit it is temporary and can always be wiped. The other is, Google Apps is proprietary and meant inclusion of that on top of the built android version such as Gingerbread is around 95MB. There is no source to Google Apps FYI :)


AIR for Android checking internet connection issue ( actionscript 3 )

Question: I'm developing a simple app for my school which will show you the newest updates from the website, but checking the internet connection seems a little problem in AIR.
I'll be more specific:

I'm using Adobe Flash CS6 to develop the app (Using AIR for android)
The app contains a menu, and the "internet frame", of which the code doesn't really work.
I've tried a couple of things already: URLMonitor(like is available = true), URLLoader(and cathing the IOError if it occurs when there's no internet connection) and something like HTMLLoader (long time ago :P, no success)
The URLLoader works "fine", but I also need to know if the webpage just isn't available (404) when there IS an active internet connection, but in either those cases it will just throw the same "stream error" , so I can distinguish them. That's why it doesn't suit my needs.
The URLMonitor also works "fine", but here comes to problem:

When testing the app on the emulator, it can without a problem detect that there is no internet connection. BUT, when exporting to .apk and running on my android device, it won't succeed in detecting the internet connectivity.
Here's my code:
<code>var monitor:URLMonitor = new URLMonitor(new URLRequest("http://www.google.nl"));
monitor.addEventListener(StatusEvent.STATUS, netConnectivity);
monitor.start();

function netConnectivity(e:StatusEvent):void
{
    if(e.target.available)
    {
      //checking the content
      output_txt.text += "\ninternet available";
      loader = new URLLoader(new URLRequest(webURL));
      loader.addEventListener(IOErrorEvent.IO_ERROR, onIOErrorLoader);
      loader.addEventListener(Event.COMPLETE, onCompleteLoader);
    }
    else
    {
      //
      //
      //     NO INTERNET CONNECTION AVAILABLE!
      //
      //
      output_txt.text += "\nno internet available";
      popupnoconnection_mc.alpha = 100;
      popupnoconnection_mc.play();
      popupnoconnection_mc.addEventListener(MouseEvent.MOUSE_DOWN, BackToMenu);
    }
    monitor.stop();
}
</code>
As you can see, it adds an EventListener to the URLMonitor, starts the checking, and the function checks the availability of the internet connection. WORKS ON THE EMULATOR, NOT PROPERLY ON MY DEVICE.
What's even more interesting:
What DOES work on my device, is when the internet IS connected. It will just show the text in my output field, but it won't when there is no internet connection!
Also, when lauching the app with an internet connection set up, then entering this frame, then going back to the main menu, then turning the internet off, and then entering this frame again, this code suddently works great!
So it has got to do something with the creation of the URLMonitor, and checking the connection at the same frame I guess, but I need a little hand here!
I think this can't be too difficult!
Thank you so much in advance! (sorry for typos)
Comment: The URLMonitor is not that sophisticated. It works by periodically trying to access the URL. It seems conceivable that a mobile device could circumvent this mechanism when it knows there is no connection. Since it relies on an HTTP request to fail, it's possible that no http request is made at all by the device when there is no connection.
Comment: thanks, I'll just trace a "no internet connection?!" to the user if the time trying to access the page is too long. Thank you again for your time
Answer: You can use NetworkInfo to detect whether there is an internet connection - it works on Android.


How does WiFi work on an aircraft?

Question: I've noticed that when a WiFi system is set up on an aircraft, a small bulbous structure is added. What does it contain and how does this WiFi system work?
Answer: The small bulb houses the antenna that provides the satellite communications for the internet link.
Inside the aircraft several wireless access points provide a WIFI signal to the passenger's equipment. The wireless access points are connected to a central modem which in turn is connected to the transceiver unit. The transceiver uses the rooftop antenna to communicate to a geostationary satellite.

source: dailywireless

source: Flightglobal

The antenna is a small dish or phased array that is aimed at the communication satellite using servo motors and/or electronic beam steering. The antenna control system receives information about the position and attitude of the aircraft to calculate the relative position to the geostationary satellites that provides the internet communications signal.
There are also systems available on the market that use a ground based network to communicate with the internet. These systems cannot provide global coverage since the aircraft needs to be in line of radio sight of a ground based antenna.
Comment: The wifi connection (link between your device and the wifi router in the airplane) is pretty conventional, in the exact same manner as the wifi connection in your home or a cafe. The pictured device and antenna are for the *internet* connection between the airplane and the rest of the world - replacing the cable or fiber optic connection that you or the cafe might have to your internet service provider.
Comment: Wow, phased array... It's only thanks to your post that I can fully appreciate the simplest thing like _a normal wifi conncetion I'm used to get all over the place_.
Comment: @immibis: I just didn't make myself crystal clear, that's all. I used to work in wireless network business (where I got the feeling of omnipresent wireless connection to the Internet) as well as non-destructive material testing, where I got to appreciate the technical and computational complexity of phased array. I have yet to get to building and launching a communication satellite, though.
Comment: Possibly Pavel is confused about the difference between Wi-Fi and the Internet?
Comment: While I see the image from Lufthansa above. They turn off the WiFi called "Fly-Net" above mainland China, beause "free as in free speech" ist not available above China. However, I'm glad that it is not allowed to make calls during flight and being not available is a pleasure.

How does WiFi work on an aircraft?


Nirenberg problem in conformal change

Question: Let $(\mathbb{S}^n,g_0)$ be the standard sphere, $n\geq 3$, consider the Nirenberg problem$$
-k(n) \Delta_{g_0} u+R_0 u=R u^{\frac{n+2}{n-2}}, \quad u>0\,\text{ on }\, \mathbb{S}^n,
$$
where  $k(n)=\frac{4(n-1)}{n-2}$ and $R_0=n(n-1)$ is the scalar curvature of $g_0$. Let  $t \in \mathbb{R}$, let $\varphi_{t}$ be the M"obius transformation on $\mathbb{S}^n$ which, under stereographic projection with respect to the north pole, sends $y$ to $ty$. For function $v$ defined on $\mathbb{S}^n$, we let
$$
T_{t}v:=v\circ\varphi_t|\det d\varphi_t|^{\frac{n-2}{2n}}
$$
where $d\varphi_t$ denotes the Jacobian of $\varphi_t$. In particular, the pull-back metric of $g_v = v^{\frac{4}{n-2}}g_0$ under $\varphi_t$ is given by $\varphi_t^* (g_v) = g_{T_t v}$.  Is it true that $$
-k(n) \Delta_{g_0}\left(T_\phi u\right)+R_0\left(T_\phi u\right)=(R \circ \phi)\left(T_\phi u\right)^{\frac{n+2}{n-2}}\quad \text{ on }\, \mathbb{S}^n?
$$
I don't konw how to verify the above equation since the $ |\det d\varphi_t|$ term in $\Delta_{g_0}$  is hard to calculate,  Thanks a lot for any help.
Answer: Yes, it is true.  This is a consequence of the conformal invariance of the conformal Laplacian.
Let $(M^n,g)$ be a Riemannian manifold.  The conformal Laplacian is
$$ L_2^g = -\Delta + \frac{n-2}{4(n-1)}R . $$
(I use the convention $-\Delta \geq 0$.)
We require two properties of this operator.
First, it is natural: If $\Phi \colon M \to M$ is a diffeomorphism, then
$$ \label{1}\tag{1} \Phi^\ast (L_2^gu) = L_2^{\Phi^\ast g}(\Phi^\ast u) $$
for all $u \in C^\infty(M)$, where $\Phi^\ast f = f \circ \Phi$ is the pullback of a function and $\Phi^\ast g$ is the pullback of the initial metric.
Second, it is conformally covariant: If $\Upsilon \in C^\infty(M)$, then
$$ \label{2}\tag{2} L_2^{e^{2\Upsilon}g}(u) = e^{-\frac{n+2}{2}\Upsilon} L_2^g \left( e^{\frac{n-2}{2}\Upsilon}u \right) $$
for all $u \in C^\infty(M)$.
Now let's specialize to your setting of the sphere $(S^n,g)$ with its metric of constant sectional curvature one.
Then $R=n(n-1)$, so $L_2^g$ is (proportional to) the operator you wrote down.
Let $\Phi \colon S^n \to S^n$ be a conformal diffeomorphism;
i.e. $\Phi^\ast g = e^{2\Upsilon}g$ for some $\Upsilon \in C^\infty(M)$.
(Your $\phi_t$ is one example of a conformal diffeomorphism.)
Then the volume element $\mathrm{dv}$ transforms by
$$ \label{3}\tag{3} \mathrm{dv}_{\Phi^\ast g} = e^{n\Upsilon}\mathrm{dv}_g , $$
and so $\lvert \det d\Phi \rvert = e^{n\Upsilon}$.
Combining Equations \eqref{1}, \eqref{2}, and \eqref{3} yields
\begin{align*}
 (L_2^gu) \circ \Phi & = L_2^{\Phi^\ast g}(\Phi^\ast u) \\
 & = \lvert \det d\Phi \rvert^{-\frac{n+2}{2n}} L_2^g \left( \lvert \det d\Phi \rvert^{\frac{n-2}{2n}} (u\circ\Phi) \right) .
\end{align*}
In particular, if you set $T_\Phi u := \lvert \det d\Phi \rvert^{\frac{n-2}{2n}} (u \circ \Phi)$ and assume
$$ L_2^gu = \frac{n-2}{4(n-1)}fu^{\frac{n+2}{n-2}} , $$
then you conclude that
\begin{align*}
 \frac{n-2}{4(n-1)}(f \circ \Phi)(T_\Phi u)^{\frac{n+2}{n-2}} & = \frac{n-2}{4(n-1)}\lvert \det d\Phi \rvert^{\frac{n+2}{2n}} (fu^{\frac{n+2}{n-2}})\circ \Phi \\
  & = \lvert \det d\Phi \rvert^{\frac{n+2}{2n}} (L_2^gu) \circ \Phi \\
  & = L_2^g(T_\Phi u) .
\end{align*}
This is precisely your equation.
Comment: Good job! Many thans!
Comment: @ Davidi Cone If you find an answer to your question correct and useful, you should accept it by clicking on the "check " sign. I think your questions are interesting. Good Luck!

Nirenberg problem in conformal change


Why do heavier elements have smaller specific heat values.

Question: In the periodic table the trend is that as the mass of each element increase's the specific heat tends to go down. This seems to be counter-intuitive because if I am not mistaken as mass increase's the amount of heat that the substance can hold goes up. So why does the specific heat of these elements go down?
Comment: There is no reason to assume specific heat is a nuclear property.
Answer: The more particles in a system, the more modes of vibration (and rotation), so one gram of $\ce{H2}$ has about $235 \times$ more particles than one gram of U. The heat is "stored" in the motions of the atoms and electrons, until reaching millions of kelvin, at which point dissociation of the nucleus would be significant in specific heat. See these links and  for more information.
Answer: As the amount of a substance increases the Heat capacity of that substance does go up. However, Specific Heat is a correction for this because it is the Heat Capacity divided by the amount of the substance.
For Specific Heat the amount of a substance is irrelevant and its value is largely determined by the degrees of freedom for the constituent particles. The more degree of freedom, other than transnational, the higher the Specific Heat. An example of another degree being rotational energy which does not contribute to Temperature changes.
Comment: This doesn't say anything about the trends in the periodic table, which is what the question is about.
Comment: This post does not answer the question and it is also incorrect since specific heat capacity _c_ is heat capacity _C_ divided by mass _m_ (not heat capacity _C_ divided by amount of substance _n_).


Solidity bytes32 to JS string?

Question: There been a couple of questions on bytes32 to string in solidity itself.  What's the best way to convert a solidity bytes32 return value to a string in JS?
Answer: you'll have a good live example of what you want in the browser-solidity,
especially in line 395 of universal-dapp.js
// decode data
                    var decodedObj = EthJS.ABI.rawDecode(outputTypes, result.vm.return);

                    // format decoded data
                    decodedObj = EthJS.ABI.stringify(outputTypes, decodedObj);

Solidity bytes32 to JS string?


Writing music for tenor sax from piano

Question: I have a famous song written for piano that I want to transpose for tenor sax. Is that the correct term? It will be put on a piece of art as a gift so its very important I do this correctly. I am very new to music (I'm learning the flute) but know nothing of transposing. I could just put the piano music as is and let him transpose it himself (right?), but I want to show my thought and effort. Any advice would be great!
Answer: Transposing (yes, that's the right word) from piano to tenor sax means moving each piano note up one whole step. For example, if middle C is written for the piano, a D should be written for the tenor.
The tenor will sound one octave lower than the actual written note. For instance, the D mentioned above would be written on the space above middle C, but the actual sound is the C in the second space of the bass clef. That's how the tenor is written, and you need not make adjustments for it — it's expected.
There are a few things to be careful of:

The lowest note the tenor can play is the Ab below middle C (Bb when written for the tenor). (The highest note — F above the treble staff — shouldn't be a concern.)
Sharps, flats, and naturals can get confusing when transposing from piano to tenor, because they can change depending on what key you're in.

Example:

Piano part is in F major. This means the tenor part will be in G major. So in the key signature, the piano part will have one flat, but the tenor part will have one sharp. Any written Bbs in the piano part will become C naturals in the tenor part. Similarly, Es in the piano part will become F#s in the tenor part. If the piano part happens to have an Eb in it, that will become an F natural in the tenor part (because Eb is a half-step lower than E, and F natural is a half-step lower than F#).
Comment: I think it's better to give the actual tenor sax written transposition, a M9, rather than a M2 and saying it will sound an octave lower. Other than that good answer,
Comment: The sax can play far above written F.  Check out, e.g., the study book "Top-Tones" by Sigurd Rascher
Comment: @CarlWitthoft Interesting. Is that including the "squeal" range of the instrument?
Comment: @Aaron - they are overtones, same as a flute does to get the 3rd octave.  I wouldn't call them "squeals" such as R.R. Kirk used to toss in.
Comment: @CarlWitthoft Yes "overtones". I understand your comment now.

Writing music for tenor sax from piano


Search 'Hangs' While Trying to Assign Transactions to a Batch

Question: I created a Smart Group of members whose memberships are expiring in a particular month.  I then created a new accounting batch.  When I open the batch by clicking 'Transactions,' I get a list of all 2,000 plus members.  Then I tried to revise my search by selecting the Smart Group in the search screen.  When I click search, I get a small box in the middle of the screen that says 'Processing...'  However, nothing happens. It appears that CiviCRM is hanging. I can find no reference to anything similar happening in any of the CiviCRM sites.
Answer: This can happen for many reason

check for any error message in Civicrm Log file
check for any error message in PHP error log file

If you haven't got any error message then

your MySQL DB is old version and you need to upgrade to latest
 Because some SQL which has been written in MySQL 5.6 is not been supported in Mysql 5.1 - which will not return any value and will timeout
also check for your Php Version too


Wordpress - preserving office location in blog

Question: Here's a puzzler:  I'm doing a site for a client that starts with a landing page that links to  his four law offices, each with a color coded header and office info.  They all have content specific to their offices, no problem. But they also have some content that's universal, like a blog.  How do I put the blog in for all the offices but preserve the office info on those pages?  No, I do not want to use frames, but yes, that's the idea I'm talking about.
Comment: what you have tried yourselves?
Comment: I haven't tried anything yet Jothi, I'm looking for a strategy to make this happen.
Answer: Couple different ways you could approach this, generally depending on how much information you need to share across the offices, whether you have requirements on how these different offices are administered, and generally how similar the content is.
The first decision to make is whether to use Single Site setup (in which they technically operate as one WP site), or a Multi-Site setup (in which you could use one common theme, but the posts/pages are administered independently  - you could still use a plugin like http://wordpress.org/plugins/network-latest-posts/ to share blog posts, but you'd want to make sure it meets your needs beforehand). More on this decision here: http://mashable.com/2012/07/26/beginner-guide-wordpress-multisite/, and setup here: http://codex.wordpress.org/Create_A_Network.
If you opted to go single-site, then one simple option may be to create page hierarchies, with the parent-level pages as Office A, Office B, Office C. If it's only a couple things that need to change based on the office (e.g. header colors, simple branding or info), then you could make a function that checks highest parent-level page (using get_post_ancestors - http://codex.wordpress.org/Function_Reference/get_post_ancestors), and use that result to determine which offices' branding you should use.
Best of luck!


Term for upward slant of horizontals in a typeface

Question: I've noticed that in a lot of typefaces simulating upright hand lettering, the horizontal strokes slant upward.
In Comic Sans and Comic Neue, this slant is especially visible on the crossbars of lowercase e and uppercase A and H.
So does the H in the logo of the Holiday Inn hotel chain.
Apple Casual shows the effect in more horizontals, as do Dom Casual, Wastrel, Blambot Casual, Segoe Print, and Tekton.
In the Apache/August family (trade names include Apache URW, Cochise, Disney Print, Jester, Stanley, and Toledo), nearly everything horizontal has a 10% grade or 6 degree skew, including glyph baselines.
The upward slope tendency also appears in ''kaishuu'', or Japanese "regular" script.
Is there a typographic term for this phenomenon in general?
Answer: This is an interesting question and I can't say that I know a simple black and white term for this phenomenon. However, in this thread (a discussion on the fall of the crossbar on the lowercase 'e' from a slanted to horizontal position in the transition of Humanist to Old Style) it is referred to as an oblique crossbar. A term that I think fits.
(Read more about Humanist and Old Style here)
As a characteristic it is simply referred to as a slanted (or less often sloping or angled) crossbar in the texts that I have found, texts that are generally discussing the differences between more organic Humanist inspired fonts VS the later Old Style in which the crossbar is horizontal. (e.g 1, 2, 3, 4)
As you mentioned though, it is a characteristic that is inherent in fonts that are more organic in style and sometimes mimic traits of calligraphy or hand writing. A characteristic that unfortunately can no longer be defined as simply a Humanist or Venetian trait as there are plenty of fonts inspired by both of these that have no angled in their crossbar.
I hope I've helped you get closer to a solid term on this, I would be really interested to know!


Trying to find MAC addresses across a network

Question: When using nbtstat -a (IP address), will it return the true MAC hardware address of the machine?
Comment: Could you add the OS (or multiple of them)? I guess everyone is assuming windows since you mentioned `nbtstat`, but that is still an assumption.
Answer: If you use nbtstat -a you need to specify a HOSTNAME.
To use an IP address, it's nbtstat -A <ip>.
Other options from Unix are arp -a (which doesn't really scan everything available).
Answer: Either:
1
Collect them from a directly connected computer, or
2
Or run a program on the local computer you are trying to get the mac from, e.g. getmac which will return output like this:

Or via vb:

strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colItems = objWMIService.ExecQuery("Select MACAddress from Win32_NetworkAdapter where DeviceID=1")
For Each objItem in colItems
    Wscript.Echo "MAC Address: " & objItem.MACAddress
Next

Source of the script: this very similar question on S.U.
3
Or get them from the switches the computer is connected to. Precisely how depends on the brand of the managed switch.
4
Or write them down whenever you get new hardware and store them in a inventory database. (Mostly useful for large corporation, which will store much more information such as model, type, CPUs, RAM, helldesk calls, ...)
Answer: True MAC address? True MAC address? Unless you pull the NIC and take it back to the manufacturer there is truly no way of knowing for sure when there are programs that can easily change your hardware address WITHIN SECONDS...
Seconds.


Jupiter FM - What are practical and inexpensive ways for the amateur detection of signals from Jupiter, especially of the transit of her moons?

Question: What modifications to a standard AM/FM or shortwave radio are needed in order to be able to detect radio-wave signals emitted from Jupiter?
Would it be possible to detect the transit of the major moons and even minor planets (maybe even Ceres and Mars) using this method?
Answer: @Arne is right in his answer about two things, that the most suitable frequency for Jovian amateur radio is 20.1 MHz, and that this is a 15 meter wavelength. However, the antenna can actually be half the wavelength, and amateur radio astronomers have had good results listening to all kinds of Jovian sounds, including detecting occultations of its many moons as they produce change in frequency due to the Doppler shift when passing in front of it, amplification due to echo of Jupiter's own radio wave signature when close beside it from the observer's vantage point, and other effects causing radio wave frequency and amplitude changes with a simple dual dipole array that might look something like this:

        The Jove dual dipole array. Dipoles are suspended between PVC masts. Signals from the dipoles go to a power combiner and        then to the receiver. Source: Amateur Radio Astronomy Projects — Radio Signals from Jupiter (PDF)
Now this dual dipole antenna is more or less a simple two-piece of roughly half the wavelength of coaxial cable, stripped of insulation at the dipole ends and run dipoles parallel to each other at roughly 6.1 meters (20 ft) apart suspended over PVC masts. That is perfectly acceptable for nearly any amateur radio astronomer in both space and the price of the parts needed. There are also ways to help oneself with a lot smaller antenna, which I'll mention a bit later. Let's first clear the frequency range discussion with this really informative quote from Radio Receiver for Jupiter webpage (based on NASA's Radio JOVE project):

The peak of Jupiter signals occur around 10 MHz. Still this frequency
  is not that suitable, as it is very near to Ionospheric cutoff. The
  best suitable frequencies are in between 18 to 22 MHz, as the chances
  of getting emissions are more. In practice 18.7 MHz, 20.1 MHz, 22.3
  MHz are common. The frequencies above 30 MHz are not suitable because
  of less strength. The frequency of 20.1 MHz is used for this project,
  as the probability of getting emission is high. So the entire receiver
  is designed considering 20.1 MHz as the operating frequency.

Antenna is of course merely one part of the story. Second thing that is required is the receiver. NASA is sponsoring Radio JOVE project with an assembly manual for roughly 100 electronic components and pieces of hardware worth RJ1.1 Receiver (Radio Jove 1.1 Receiver) that can be almost completely assembled out of parts ordered from Radio Shack (it even includes RS part numbers). I'll add a photograph and a few other links, and you'll have to be on your own then:

   Self-assembled Radio Jove Receiver's front plate with two turning knobs for volume and tuning. Source: KB0LQJ Observatory
Some relevant links for building Radio Jove (or Jupiter FM, if you like, it will be your own receiver so name it as you wish), starting with already mentioned ones:

Amateur Radio Astronomy Projects — Radio Signals from Jupiter (PDF)

Ten years ago a group of (mostly)
  University of Florida graduates working at
  NASA conceived an educational outreach
  program known as Radio Jove. The idea was
  to build an inexpensive radio telescope kit
  suitable for detecting signals from Jupiter.
  The Jove receiver (Figure 2) is a simple
  direct-conversion design operating over a
  few hundred kilohertz range centered at
  20.1 MHz.

NASA's Radio JOVE project (PDF)

The site is currently down due to US government shutdown, so here's a Google cached version that sadly doesn't come with in-document images

KB0LQJ Observatory Amateur Radio Astronomy — Radio Jove observations

For my home observatory, I started with the Radio Jove receiver from NASA's Radio Jove Project. This was a fairly easy-to-build kit with great directions, not just for the receiver but also the antenna setup and installation.  Unfortunately, I don't have enough space to put up a phased antenna array.  Also, I'm bordered by power lines on the north and south sides of my property.   Also, since I'm in an urban area, I knew that I'd pick up a lot of noise.   Not to worry.   Solar observations are also quite interesting, and since the Sun is such a good signal source (especially so far this year), I opted for an antenna in my attic.

Radio Receiver for Jupiter

This website contains the Technical details of the antenna and receiver used for receiving natural radio emissions from Jupiter at 20.1MHz. The antenna and receiver discussed in this site is based on the design given by NASA Radio Jove Program.
  Natural radio emissions from Jupiter or from Sun are detected by using a dual dipole array as an antenna and with a sensitive receiver. The RF voltage developed at the antenna terminals is amplified with the RF amplifier and converted in to audio frequencies using a mixer. The audio signal thus generated is recorded on PC through a sound card in 'wav' format. Also a strip-chart recorder software is available to generate the strip-chart of data coming through sound card.

So there are indeed many ways to build your own antenna and receiver out of affordable and easily obtainable electronic parts, and some of these websites listed above will help you through the process of self-assembly, even providing some tricks how to do it easier, like for example assembling a smaller, in-house antenna array.
Now, one other thing that all these websites mention is also using various PC software that lets you analyze through computer's sound card received Jovian radio sounds, but since there's many different and free solutions out there, including NASA's own that runs on Windows PCs, I'll let you discover those on your own. Here's one page listing many links, to get you started. More computer savvy of you might even write your own software for this purpose, this is Stack Exchange afterall.
And if anyone is wondering what such self-assembled radio receivers and antennas are capable of, here's a link to a collection of various Jovian sounds in the radio wavelengths on Astrosurf.com, and another one as a collection of solely amateur radio astronomy sounds of Jupiter and its moons (scroll a bit down to the list of recordings). And here's a short description of various sound types one might hear:

Chorus (quote source: The University of Iowa Department of Physics and Astronomy)

Chorus consists of brief, rising-frequency tones that sound like the chorus of birds singing at sunrise, hence the name "chorus" or "dawn chorus." Chorus at Earth is generated by electrons in Earth's Van Allen radiation belts. Once generated, the chorus waves affect the motions of the electrons through a process called a wave-particle interaction. Wave-particle interactions disturb the trajectories of the radiation belt electrons and cause the electrons to hit the upper atmosphere.

Decametric noise storms (quote source: Radio-Jupiter Central on RadioSky.com)

The emissions we can hear are often referred to as decametric noise storms, because the waves are tens of meters long. Okay, it is possible to hear Jupiter from 15 to 38 MHz, but what are the optimal frequencies?  The consensus seems to be that 18 MHz up to about 28 MHz is a good place to listen.  A good rule would be to pick the lowest frequency in this range which was not being hindered by ionospheric refraction.

Whistlers (quote and image source: Wikipedia):

A whistler is a very low frequency or VLF electromagnetic (radio) wave generated by lightning.1 Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with a maximum amplitude usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strokes (mostly intracloud and return-path) where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other.

Auroral Radio Emissions  (quote source: Wikipedia)

Auroral radio emissions from giant planets with plasma sources such as Jupiter's volcanic moon Io could be detected with radio telescopes.

And so on. The last two on the list are probably a bit of a stretch for amateur astronomers, with auroral radio emissions average frequency range at 100 to 500 kHz, and whistlers cutoff at usually around 30 kHz, and both requiring too big antennae, but I wouldn't bet against it being possible with smaller antennae either, although bow frequency cutoffs might prevent identification of actual aural events. But there are many other sounds to listen to both from Jupiter, as well as it's many moons, mostly though the bigger and closer ones.
Good luck tuning in to your own Jupiter FM and happy hunting for rare radio frequency events!
Comment: I would never have guessed that it might be possible with such an easy setup. Very good answer!
Comment: Same here.  15m is such a busy terrestrial band that I'm amazed that a dipole (not terribly directional) would pick up Jupiter without being swamped by all the local signals!
Comment: There are many fine detail points to making this all work, essentially a lot of fine tweaking, but that's already something an amateur astronomer should enjoy greatly. Antennae can be even smaller than half-wave dipoles (e.g. Hertzian dipole) but they won't achieve dBi (decibels relative to isotropic radiator) as high, so other factors will play a major role, like use of narrow band and low pass filters. But that could stretch several more pages long to properly answer, so I thought to just let readers find their own answers, or perhaps ask new questions. It would IMO make a great blog topic.
Answer: The StarGazers lounge featured a radio kit article for Jupiter radio astronomy. The same article is also featured over at the Radio Group of BritAstro.
It seems that 20.1 MHz is the suitable frequency for amateurs observing Jupiter. I am far from being an expert for radio astronomy, but for a small source such as Jupiter, I would assume that you need a big parabolic dish (for antenna gain and directionality), and a proper feed antenna, suited for 20.1 MHz. You will probably also need to have a motorized mount for the antenna, to track the motion of Jupiter across the sky.
I will post more info, after I have asked a friend, who's an expert on antenna design, which configuration may be suitable.
Edit: Ok, the infos are in. A parabolic dish is out of the question -- 20 MHz corresponds to about 15m wavelength. And dishes need to be many multiples of a wavelength. So we could use a dipole antenna, but those are not very directional. Also, the dipole needs to be rather large, for good gain. To make it directional, you need an array of steerable dipole antennas.
Summary: I think it is not really feasible to do this on an amateur scale. Of course, I am gladly being proven wrong!
Answer: There are posts mentioning it not being practical for amateurs because of the size of the antenna (generally) required combined with the need to "point it" in the right direction.
One answer to this is -- if you can just point a static antenna structure toward the sky (front poles supporting the forward-most element higher than the real-most support poles supporting it, thereby angling the beam toward space) then you simply let Earth be your antenna motor. The excitement comes from waiting for the precise time that Jupiter naturally moves through your window of opportunity.
This is a wonderfully feasible method of aiming huge wire antennas toward space for pretty low frequency signals of all kinds.
As far as "never knowing if it's just a terrestrial signal", for one thing, man's signals are not super-ultra-wide band like that. Receiver parameters should be set before being aimed at Jupiter, and results compared before and after. Plus there are all sorts of other tests and identification factors. With enough know-how, which is the free and laborless aspect of it, one can rule out man and extraneous natural interference.
Answer: At a minimum, you'll need a highly directional antenna appropriate for the frequencies in question (I do not know what they are).  The radio would also have to able to detect the frequencies that you expect to hear signals on.
Comment: -1 No research effort demonstrated. Other answers found specific frequencies.


Buying pre-downloaded games from playstation plus

Question: What do I do if during my PS+ membership, I download a game, and after playing it, I want to buy it. However when I go to buy, it says "Already Purchased"?
Comment: Might have to wait for PS+ to lapse before it offers to let you buy it maybe? I've never had my sub lapse to check. And you're talking free on PS+ games right, not free trials? For free trials you have to run them once and let the 1 hour timer run down before PSN will let you purchase the game, it's a little awkward.
Answer: You need a second "non PS+" account to buy either already "purchased" zero-price PS+ game, or just to buy a game at full price then it's on a PS+ zero-price "sale". And of course you can buy a game after your PS+ subscription ends.
This is an old known issue and it seems that Sony didn't really want to do anything about it.


Doctrine2, uniqueConstraint on JoinColumn for ZF2?

Question: I have a data feed that has duplicated content (no idea why, it's an external feed), however we need to insert all items with a constraint on the title and type, i.e.
These can exist:

Name_A, Type_A
Name_A, Type_B

But only one of these should exist:

Name_A, Type_A
Name_A, Type_A

Here's the Entity code I'm using:
/**
 * Restauration
 *
 * @ORM\Table(name="restauration", uniqueConstraints={@ORM\UniqueConstraint(name="name_unique", columns={"name_1", "restauration_type"})})
 * @ORM\Entity(repositoryClass="iMotionTools\Repository\RestaurationRepository")
 */
class Restauration
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer", nullable=false)
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="NONE")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name_1", type="string", length=128, nullable=true)
     */
    private $name1;

    /**
     * @var string
     *
     * @ORM\ManyToOne(targetEntity="RestaurationType", cascade={"persist"})
     * @ORM\JoinColumn(name="restauration_type", referencedColumnName="id")
     */
    private $type;
}

But I get this error when parsing and inserting the data:
SQLSTATE[23000]: Integrity constraint violation: 19 columns name_1, restauration_type are not unique:91:C:\coding\currate\vendor\doctrine\dbal\lib\Doctrine\DBAL\DBALException.php

I'm wondering whether the easy way is to just ignore the thrown exception? Looks like it's a driverExceptionDuringQuery that gets thrown during my call to $em->persist(); but I'm not sure how I would ignore if the call contains the above error?
Answer: If you want to ignore that, stop using constraint integrity.

{@ORM\UniqueConstraint(name="name_unique", columns={"name_1" //etc...

Your data has name_1 not unique this is why you have this error, integrity constraint check this, you can't ignore that, without remove the unique constraint parameters.
Edit :
You have to then, before persist data, check with your actual data in the table, if there is a duplicate entry for both name_1 AND Type, and do not persist them.
for check both you can use :
@UniqueEntity({"name", "type"})

found here :
validation multiple constraint columns
Even if it's for SF2, it's the same concept
Comment: I cannot use name_1 as unique since we have to have duplicates of name_1 with different "type"s... Ideally I want to catch the error and ignore only if it's for this duplicate 19 error (throw otherwise), or have the generated SQL come up with something like INSERT OR IGNORE INTO ? but not sure if that exists for sqlite?
Comment: The UniqueConstraint is there specifically so that we don't get duplicates of the same name + type (i.e. NameA, TypeA twice. but we accept NameA and different TypesA,B,C etc.)
Comment: check the data before persist them maybe.. and don't persist them if there is duplicate
Answer: I've removed the UniqueConstraint attribute from the table and added a function to check the objects list (which later get $entity->persist()-ed), using an array so that I can easily use it for different entity types, and it seems to work well now.
        $key = $hashList ? '' : $page['id'];
        foreach ($hashList as $method) {
            $val = $object->{$method}();

            if(is_object($val)) {
                $val = $val->getId();
            }

            $key .= $val;
        }

        $key = md5($key);

        $objects[$key] = $object;

Where $hashList = array('getName', 'getType') - and getType returns an object (since it's another entity), but which always has the getId() function... probably not the best solution but it works for my situation...


Windows 8.1 evaluation version sets the resolution to 1024X768

Question: Windows 8.1 evaluation version sets the resolution to 1024X768 and is not letting me change it. Although my Laptop supports 1366X768. How can I change it as the icons are looking too big and the user experience is bad. Any help will be useful.
Comment: It sounds likely that you have a display driver problem. Try reinstalling it from scratch, from your graphics card's website. (if it's onboard graphics like in so many laptops and you can't for the life of you figure it out, there's a good chance it's Intel or AMD, same as the motherboard/processor.
Answer: you just have to install display driver for your graphic card.


365 - Mail-enabled public folder not visible in EAC, Outlook, or Get-PublicFolder. BUT visible to Get-MailPublicFolder

Question: I'm encountering a strange Exchange issue I haven't been able to figure out.

Exchange Online (Office 365).
Originally was an Exchange 2010 environment, migrated via O365 Hybrid Config, hybrid has since been decommissioned and the organization is cloud-only at this point.

Problem -
It appears that I have several 'orphaned' public folders.
Get-MailPublicFolder lists numerous public folders that don't appear in the output of Get-PublicFolder.
Get-PublicFolder -Recurse |Where-Object{$_.MailEnabled -like "*true*"} returns 11 results.
Get-MailPublicFolder returns 37 results.
The mail-enabled public folders that aren't returned by Get-PublicFolder don't display in Outlook or in the EAC.
If an email is sent to them, an NDR is returned stating the recipient cannot be found.
I compared the attributes I could see in Get-MailPublicFolder between one that is missing and one that does appear, and saw only one difference that I thought relevant - HiddenFromAddressListsEnabled. Contrary to what I would expect, the value for that was set to TRUE for the PF that WAS visible, and the attribute on the missing PF was set to FALSE. While this seemed the exact opposite of what I'd expect I went ahead and changed the attribute on the missing PF to TRUE to match the functioning PF. That made no difference.
I also noticed the 'SimpleDisplayName' attribute was null. I added a value to that, still no difference. (SimpleDisplayName is null on the working PF as well.)
What can I do to get my missing MailPublicFolder to be listed by Get-PublicFolder and displayed in my EAC? And if that isn't sufficient, to get the folder to receive emails sent to it? Clearly there is some disconnect somewhere preventing EOL from seeing this public folder, and I expect that the proper fix will resolve all of the various problems stemming from its invisibility.
Thanks, Steve
Answer: Are those invisible public folders belonging to the same public folder mailbox?
Firstly, you can try the following methods:
In outlook, you can try to disable cached Exchange mode. There is a similar case for your reference.
In EAC, you can use Get-PublicFolderClientPermission -Identity "\My Public Folder" -User xx | Format-List to check user permissions. For more details:Get-PublicFolderClientPermission
In addition, the problem described on NDR likes be caused by the public folder mailbox, you need to check if the mailbox is working properly.
Comment: Any updates? Have your issue been solved? Have my suggestions been feasible?


Batch Apex Error - Class must implement the following methods System.ScheduleableContext)

Question: I am trying to update a batch class to allow me to schedule it, but I am getting this error:
Class must implement the following methods System.ScheduleableContext

I understand the error, but given my code works when I manually execute the job I am not aware how to update it to still work and also be schedulable.
public class DataRefreshBatch implements Schedulable, Database.Batchable<SObject>,  Database.Stateful,  Database.AllowsCallouts{

    public List<Jobs__c> start(Database.BatchableContext bc) {
     /*....*/
    }

   public void execute(Database.BatchableContext bc, List<Jobs__c> scope) {
     /*....*/
   }

    public void finish(Database.BatchableContext BC) {
    }
}

The error is in the first line, when I added "Scheduleable" after implements, I get an error in my IDE showing the error message above.  My start method returns a list of records from a custom object that I then use in my execute method.
What modification is needed to allow me to make this class scheduleable and still keep the method signature the way it is on my execute method.
Answer: You need to include an execute(SchedulableContext) method. Typically:
public void execute(SchedulableContext context)
{
    Database.executeBatch(this);
}


Can't click on jslint errors in NetBeans

Question: I'm trying to configure a NetBeans build to call jslint and produce errors that I can click on to take me to the source.
Using the Maven build script from Maven plugins to analyze javascript code quality, jslint is running and producing errors but I can't click on them.  The text in the NetBeans output window looks like this:
<code>[jslint] C:\Documents and Settings\arx\My Documents\Progs\jsweb\src\main\wwwroot\jsweb.js:125:48: 'keydown' is not defined.
</code>
I'm running NetBeans 6.9.1 on Windows.  The spaces in the path aren't an issue.  I tried it with a spaceless path and it still didn't work.
Ultimately I want to edit a simple javascript+html project in NetBeans and have clickable errors from jslint.  I'm not wedded to Maven.  Any suggestions gratefully received.
Update: A solution
If I put jslint4java directly into an Ant project (rather than an Ant project wrapped in a Maven plugin) the output doesn't include the [jslint] prefix and I can click on the errors.
This is a bit of a chore because it seems to be necessary to explicitly list the locations of all the jar file dependencies, but it works.
Another Update
I'm having another go at making this work in Maven because its java dependency management is nice.  The problem is definitely the [jslint] prefix in the output, which is produced by Ant.
There doesn't seems to be any way of making NetBeans ignore the prefix, which is odd because Ant is NetBeans's default build tool.
The prefix can be suppressed by setting the emacsmode property on Ant's DefaultLogger.  NetBeans does this when it lauches Ant iself (if "build.compiler.emacs=true" is set in Options), but maven-antrun-plugin doesn't (and looking at the source, there's not currently any way of persuading it to).
Possible fixes are:

Make NetBeans better at decoding Ant output.
Add an emacsmode option to maven-antrun-plugin.
Find a native Maven jslint plugin (so Ant isn't used at all).

Option 3 looked like potentially the simplest so I used TortoiseSVN to download the source for http://mojo.codehaus.org/jslint-plugin/ from https://svn.codehaus.org/mojo/trunk/sandbox/jslint-plugin and got it working.  But it produces NetBeans-unfriendly output like:
<code>[ERROR]jssvg.js:2690:48:'keydown' is not defined.
</code>
Comment: Thanks for updating your original question with good observations.
Answer: The easiest way is to add this plug-in. Supports the Netbeans 7.3.


Blender 4.1 USD export not applying modifiers

Question: Very pumped about the USD armature and shape key export features added in 4.1. But when I tried it out just now, many of my modifiers are not being applied on export like they used to. So far I've noticed simple deform and subdivision modifiers that aren't exporting. Is there a trick to this now? I've looked all around for a checkbox or something like there is with .glb exports, but I've got nothing. I won't be able to use this feature for my animations in this state.
Answer: Ok, got to digging around in the more detailed release notes (check the link below). Turns out this is not a bug. It was a known consequence of the changes. Too bad it came with some major compromises. I'm going to have to gum up my files with an un-subdivided version for animation, and a subdivided version for export. Hope they figure out how to solve this soon.
https://projects.blender.org/blender/blender/commit/c6d61e8586


How regularization parameter in SVM affects hyperplane parameters

Question: While learning the SVM classification I came across the regularization parameter $\lambda$:
$F(w,b) = \left\lVert w\right\lVert_2^2 +\lambda \sum_{i=1}^n max(0,1-y_i(w^Tx_i +b)).$
So from what I understand, the main point of SVM is to find the hyperplane $\{w^Tx+b=0\}$separating 2 classes. How does $\lambda$ affects the hyperplane parameters w and b? I tried to plot the 2D case, but still can't get it. Can anyone give the interpretation in this case? Thanks.
Answer: This is really an interesting question.
In fact, many people like Svm, many use it, many understand the idea of svm " maximize the distance between the two margins "subjects to the condition of classifying all the samples correctly!! Quite easy but can get a little bit more complicated when we are dealing with none separable data and overfitting problems.
In your question, you mentioned that this parameter is helpful to perform regularization, but why we need regularization? The answer is to avoid overfitting.
But what is overfitting? Overfitting is a problem of overfitting the data. Overfitting can be more serious if you have noisy data.
In Svm, you can think about the distance between the margins as an indicator of how much you are fitting the data. If the distance is too small, then you are trying to fit " seperate between" the samples that are very close to each other. Usually, if two samples are very close to each other and they have different labels, one of them is incorrect, or it is a noisy sample.
Now, from your question, you have two parts, the first part control the distance between the margins, the second part controls the error in miss classification. Changinging " increasing" lambda will give more attention to the error rather than the distance.
The more you reduce lambda the maximum the distance between the margins you can get.
Why you do not see this clearly in your plot?
Because you plot the hyper plane between the two margins, if you can plot the margins, you will see how changing lambda is affecting the distance between the margins.


multiple JSON objects in fromJSON

Question: I'm trying to use fromJSON() to read in a .json file with multiple objects structured as follows:
{ "key11": value11, "key12": value12 }
{ "key11": value11, "key12": value12 }
…

If I manually add [...] brackets around the entire file, and , commas between the objects, then the following code works:
json_file <- "file.json"
json_data <- fromJSON(json_file,flatten=TRUE)

But adding the brackets and commas is not feasible for what I'm actually trying to do (I did it on a  sample file).
I tried using readLines() since the objects have newlines between them, but I didn't get anywhere.
How can I read in these json objects without modifying the file?
Answer: Assuming you know it's one per line, and no weird line breaks,
 lapply(readLines(filename), fromJSON, flatten = TRUE)

Answer: if you read references: the option unexpected.escape is available.

unexpected.escape
  changed handling of unexpected escaped characters. Handling value should be one of "error", "skip", or "keep"; on unexpected characters issue an error, skip the character, or keep the character

multiple JSON objects in fromJSON


How many outcomes of a coin being flipped 12 times have exactly 4 heads?

Question: I know that there are a total of 4096 possible outcomes of tossing a coin twelve times, but I do not know how to calculate the number of possible outcomes with exactly 4 heads, with at least 2 heads, or at most 8 heads.
Answer: Exactly 4 heads: This boils down to choosing 4 "spots" out of the 12 "spots" to put the 4 heads outcomes. That is, $\binom{12}{4}$.
At least 2 heads: $2^{12}- \binom{12}{0} - \binom{12}{1}$ subtracting the possibility of 0 or 1 heads.
At most 8 heads: $2^{12}- \binom{12}{12} - \binom{12}{11} - \binom{12}{10} - \binom{12}{9}$ subtracting the possibility of 9 or more heads.
Comment: What do the two numbers in the parentheses mean? I haven't seen that before
Comment: @Craig http://en.wikipedia.org/wiki/Binomial_coefficient One way to calculate them is $$\binom{n}{k} = \frac{n!}{k!(n-k)!}$$ where $n! = n \cdot (n-1) \cdot \dotsb \cdot 2 \cdot 1$.


Best Way to tackle to time series classification problem?

Question: I have a dataset where the input is a dataset for ICU patients where each ICU stay has 40 features (20 vitals, 20 lab values) and multiple time steps (the stays' length is between 6 and 19-time steps). The output is the 20 lab values (represented as binary numbers where 1 means the lab value is in range and 0 is out of range). The task is to predict the future output for an input ICU stay.
I have tried to make it a sequence to sequence problem where the output is a sequence shifted by a one-time step. However, the results were not good enough.
The question is there a way to better tackle this problem? (like maybe windowing ?)
Answer: Since I don't see the data and I cannot fully understand the data format, I am just giving some general advice. But first, I should mention that it doesn't make sense to consider each output (each 20-element array) as timeseries sequence unless there is a priority among them (by priority, I mean if you know a particular lab value is obtained before others)
So, if you have 20-element array of binary numbers as output, you might find out there is no two ouput exactly the same or there might be only a few observations with exactly similar output (because you can have $2^{20}$ combinations!). So, let's say if you have N observations, and you may see N distinct output array as well. Therefore, you may first cluster the labels into k groups and assign new labels to each group (the label of group i-th is i). Then, find the closest distance between your query and each group, so you can then find the appropriate class. Then, you can predict the ouput in array format (e.g. let's say you realize your query belongs to a group of 20 members). So, you can say, the output is expected value of output arrays in element-wise manner. So, e.g. your first element of 20-element output array might be 0.9. Or, you can be more precise and after finding the appropriate group, define a weight based on the distance between your query and members and find the weighted average of output arrays of that group!


Sybase ASE server request logs

Question: Is it possible to log each SQL query statement received from clients for a Sybase ASE server 15.7 ,  same as SET general_log = 1; command for mysql.
Thanks
Answer: you could enable the MDA tables (little performance overhead) then use first sp_monitor 'statement'. If it is not enough, you could select into the MDA tables to see the statement running in ASE server such as:
print "**** SQL of the 10 statements having the most CPU time used ****"

select top 10 a.KPID,a.BatchID,a.LineNumber,a.CpuTime,a.StartTime,b.SQLText
from master..monSysStatement a, master..monSysSQLText b
where a.KPID = b.KPID
and a.BatchID = b.BatchID
order by a.CpuTime desc

List of MDA tables:
http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc70002.1550/pdf/asemtpst.pdf

Sybase ASE server request logs


replace shimano st-ef-41-l with shimano alivio left shift

Question: My shifter st-ef41 is broken the only available shifter is the Shimano alivio or the Shimano acera. please advise Asap
thanks
Answer: Any Shimano front shifter of the same shift family (mtb triple) should work.
At work, I have used old, parts-bin shifters as replacements on repairs due to the 2020 shortage without issue, including front shifters for old mountain or hybrid bikes, and 8-speed shifters on 7-speed drivetrains.
si.shimano.com has the compatibility charts for Shimano components. the relevant part for MTB front shifter compatibility is here: https://productinfo.shimano.com/#/com/?cid=C-432&acid=C-445
if you want to confirm that the cable pull of the Acera or Alivio 3x shifter matches that of your ST-EF41, you can see that in the section "Front Drivetrain Compatibility [mtb]" ST-EF41-L appears in the box for 3x7 front shifters (SL/ST). we also see, for example, that the ST-EF505-L appears in the same box. from this we deduce that the cable pull is the same between the EF-41-L and EF-505-L.
ST-EF505-L also appears in the section for 3x9 front shifters, where it shares a box with Alivio and Acera 3x shifters such as SL-M4000-L, indicating that the 3x front shifter cable pull is shared among these systems, at least up to the level of Alivio.
You'll have to figure out what to do for a brake lever, assuming you get the standalone shifter and not an integrated unit. ST-T4000-L and ST-T3000-L are the integrated controls with mechanical brake levers and the Alivio or Acera name, although they're not the only options. often with older bikes we have simply cut the shifter portion out of the old integrated control to make room for the new shifter, rather than installing a new brake lever.
Either an Acera or Alivio 3 speed front shifter will work, in terms of having the correct cable pull. Alivio is the slightly higher-end group. if you want help choosing between the two, you can look up the shifters by part number in the specification handbook, provided you know which models you want to compare. if the Alivio option is M-4000, you'll need to go back a year or two.


How do I add breaking points to my layout.xml?

Question: I want to remove a certain block on my website but only for desktop resolutions.
How do I add a breaking point to my default.xml inside my theme?
Answer: You should be doing this with css and your break points in there. If the page is loaded and the browser window is resized then your page won't displayed as expected. Depending on your css framework would depend how you do this. If you don't have a css framework then you can simply add in your own media queries


SQL Server 2005 - Order of Inner Joins

Question: I have a query containing three inner join statements in the Where clause. The query takes roughly 2 minutes to execute. If I simply change the order of two of the inner joins, performance drops to 40 seconds.
How can doing nothing but changing the order of the inner joins have such a drastic impact of query performance? I would have thought the optimizer would figure all this out.
Comment: It shouldn' normally.  id you test it both ways more than once?
Can you post both versions?
Answer: SQL is declarative, that is, the JOIN order should not matter.
However it can in practice, say, if it's a complex query when the optimiser does not explore all options (which in theory could take months).
Another option is that it's a very different query if you reorder and you get different results, but this is usually with OUTER JOINs.
And it could also be the way the ON clause is specified It has to change if you reorder the FROM clause. Unless you are using the older (and bad) JOIN-in-the-WHERE-clause.
Finally, if it's a concern you could use parenthesis to change evaluation order to make your intentions clear, say, filter on a large table first to generate a derived table.
Answer: Because by changing the order of the joins, SQL Server is coming up with a different execution plan for your query (chances are it's changing the way it's filtering the tables based on your joins).
In this case, I'm guessing you have several large tables...one of which performs the majority of the filtering.
In one query, your joins are joining several of the large tables together and then filtering the records at the end.
In the other, you are filtering the first table down to a much smaller sub-set of the data...and then joining the rest of the tables in. Since that initial table got filtered before joining the other large recordsets, performance is much better.
You could always verify but running the query with the 'Show query plan' option enabled and see what the query plan is for the two different join orders.
Answer: I would have thought it was smart enough to do that as well,  but clearly it's still performing the joins in the order you explicitly list them... As to why that affects the performance, if the first join produces an intermediate result set of only 100 records in one ordering scheme, then the second join will be from that 100-record set to the third table.
If putting the other join first produces a first intermediate result set of one million records, then the second join will be from a one million row result set to the third table...
Comment: The query plan will generally re-order joins optimally, but it's given a timeout within which it can optimize a query. If the query is very complicated, it will actually give up and use the best plan it's found so far. If you click "Show Execution Plan XML", you'll see this as `StatementOptmEarlyAbortReason="TimeOut"`

SQL Server 2005 - Order of Inner Joins


What is the title (position) of a person who finds deals with other companies?

Question: We currently have a small Software company. We have a couple apps, but we also provide software outsourcing. We want to create (a) position(s) for someone who seeks and arranges outsourcing deals with other companies by any means possible. Is there a title specific to this role? Or is this a kind of marketing/selling? If there exists one, is there a hierarchy (Senior/Junior etc) for that role?
Comment: The first thing that comes into my mind would a _key account manager_. Though the definition probably varies from country to country.
Comment: "sales".  would be the usual term
Answer: Usually some variation on 'Account Manager' once there is a contract.
Prior to that it's marketing.
With software companies I have seen CTO's (Chief Technical Officer) who do the negotiating and liaison with outside companies.
Answer: You want a sales person - some might give it specific titles such as "Business Development Executive" or similar but it means the same thing in this context. You want a sales person.

is there a hierarchy (Senior/Junior etc) for that role?

Only if you create one.


What exactly people mean when they say "X is a $Y billion industry"?

Question: I'm reading the "Personal MBA" book right now and it says that "Yoga is $8 billion industry worldwide". What does it mean? And how can one calculate the amount of money in some industry?
Answer: Considering the economic of world as a whole it could simply refers to that total spending by people on yoga might be \$8 billion. As in an economy total spending is the total revenue of a sector. For this particular scenario it simply means that yoga as an economic variable have transaction of \$8 billion.
Regarding the calculation we can de assured that no exact and absolute calculation could be made on national level how could it be calculated exactly at global level. However the estimated aggregated spending on yoga sector nation could be determined. Which further on processing might result to provied aggregate global spending on yoga as a figure, which is tentative not exact figure.
Answer: It's ambiguous - that is, the term is used to mean several different things.
It could mean that \$YYY is the annual turnover of the industry. Or the total market capitalisation of companies in the industry. Or possibly the annual investment in the industry.
In your particular context, of "Yoga is \$8 billion industry worldwide", I'd expect it probably refers to the annual turnover of the industry
Comment: Actually, the book must either be old, or be referring to just yoga instruction. Figures from 2016 suggest \$80 billion worldwide and \$16 billion in the US alone. Those estimates include both yoga classes and merchandise (yoga mats, clothes et cetera). http://bwdisrupt.businessworld.in/article/Yoga-The-Multibillion-Dollar-Industry/21-06-2016-99432/
Comment: @KlasLindbäck that's astonishing. That's USD500 per year, for 10% of US citizens, isn't it?
Comment: In Sweden, where I live, attending yoga classes regularly will set you back at least 500 US dollars per year. So while I was initially surprised, I cannot say that the numbers seem unreasonable. In Sweden, I think regular gyms are more common and yoga studios less so than in the US.
Answer: My understanding is it is the estimate of total revenue firms in the industry could potentially make. Analysts come up with the total estimate by considering the demand for the service or product in the industry and price ranges at which the product/service would be sold.
Answer: It depends. For example:

a report about crowdfunding from the World Bank refers to amount of investment:

Crowdfunding based initially on soliciting pledges or
donations has emerged as a multibillion-dollar global
industry. [...] Projections for the size of the crowdfund investing
market range from US\$3.98 billion (Best, Neiss, Stralser,
and Fleming 2013) to as much as US\$300 billion over
the coming years depending on the level of enabling
regulation adopted by governments (Huessner 2012).

This report by World Bank about agribusiness in Africa refers to "Value added and household expenditure" (Box 3.1, page 15) when they say:

Agriculture and agribusiness together are project
ed to be a US\$ 1 trillion industry in Sub-Saha-
ran Africa (SSA) by 2030 (compared to US\$ 313 billion in 2010)

this article about cancer refers to a billion dollar industry in terms of:

[i]n 2012, the reported spending on cancer treatment was 124.6 billion dollars.

Perhaps more oddly, this article refers to pollution as a billion dollar industry in terms of the economic costs it imposes to the economy:

For example, the United States is estimated to lose \$45 billion every year due to air pollution, while the UK loses \$7.6 billion annually. Germany comes in at \$18 billion

In summary, there is no universal agreement on what that is supposed to mean. As the examples above show, it depends on the context.


Can you purchase medical/dental insurance after you know you will use it?

Question: Currently I do not have dental insurance with my job. I just found out I need some major work :( Can I still get dental insurance and have it save me money? I know it's possible to get dental insurance outside of the job because after I quit my old work the insurance company tried to sell me a plan (Manulife).
Answer: The Manulife link you provided says:

Your coverage is guaranteed with no medical questions when you apply and pay your first premium within 90 days of your employee benefits ending.

That implies that for new coverage, you will be asked medical questions.
And of course your answers will affect whether they accept you, what your rates will be, and what will be covered.
Answer: You can submit an application for insurance, but you must disclose all of your existing conditions and your family history. Anything that is relevant must be disclosed on the application form. If you neglect to mention your dentist's quote for the substantial work you need, this is known as insurance fraud (which is a criminal act).
As others have mentioned, it is common for insurers to have a waiting period (also known as a stand-down period) of around 6-12 months after your application is approved before you can make a claim. So that means even if they accept you knowing that you have a pre-existing condition, you could be waiting for a long time before your insurer would cover the claim. They would also typically charge you higher premiums as they know you'll be more likely than average to make claims in the future.
If you decide to wait out the 6-12 month waiting period, your dental health problems could get much worse over that time, or more painful. So most people would just pay for the dental treatment themselves rather than wait that long. There are finance companies that offer medical loans for people who urgently need health or dental treatment but don't have the savings to pay for it. So that is another option for you. But it is cheaper to borrow off family, if you can.
Answer: No, all dental insurance that I know of will have waiting periods for major work. Many will not have waiting periods for routine cleanings, but that won't help you.
Aetna has a dental discount program without a waiting period. But, if you shop around, you can probably get work done for the same cost without the discount.
Comment: How long is the typical waiting period on Canadian dental insurance? Major work doesn't necessarily mean urgent, so might be fine. Does Canadian law allow insurance to deny coverage for preexisting conditions?
Comment: @HartCO *Does Canadian law allow insurance to deny coverage for preexisting conditions* yes, for specific types of plans and specific conditions, and within specific time frames of your last coverage and/or diagnosing the condition, insurers are allowed to deny you, deny specific claims, or increase your premium. It's very different and more complicated than the blanket, black-and-white pre-existing condition protections we currently have in the US.
Answer: Not sure about Canada but insurance typically involves an open enrollment period or major life events.
Open enrollment:

For one month out of the year (specified by the employer) employees are allowed to freely sign up for, change, or cancel their insurance plan

Major life events (when this happens you can make changes to your insurance):

Change in marital status (marriage or divorce)
Change in household size (someone is born or someone passes)


Gravitational Potential Energy to Kinetic Energy Confusion

Question: Say there is an object being dropped from a distance. I can calculate the GPE of that object using $GPE = mgh$. As the object falls, the gravitational potential energy is converted into kinetic energy. However, it's when the object reaches terminal velocity, its velocity is not changing, so there is no change in kinetic energy $KE = 0.5mv^2$, so where is the GPE being lost being transferred to? At terminal velocity, does an object have no GPE? (has it already all been transferred to Kinetic?)
Answer: Without air, a body in free fall experiences a simple transfer from GPE to KE; KE and speed increase as long as GPE is decreasing.
With air present, the body still transfers energy from GPE to KE, however due to collisions with air molecules, energy is also simultaneously transferred from KE of the object to the air (as thermal energy, and as bulk KE of the air).
As speed increases, the drag force increases, and so does the rate of energy transfer to the air. At terminal velocity, the rate of energy transfer for those two processes (GPE ==> KE, and KE ==> air) are equal; GPE is transforming into KE, and KE is transforming into energy of the air at the same rate, which is why speed stops increasing.
Comment: Thanks, that make sense now, I don't know why I overlooked drag
Answer:
so where is the GPE being lost being transferred to?

Transferred to the air molecules hitting on it.

At terminal velocity, does an object have no GPE?

Yes, the whatever energy gained by GPE is being lost to the air molecules. The condition that must hold here that rate of energy gain by GPE is equal to the rate of energy lost to air molecules.
Comment: In other words, air resistance is significant.


How would I show empty group headers in the DVWP in SharePoint 2007?

Question: I have a DVWP that I wish to model after a physical binder-based file system. I have a column named 'Title' and a column named 'Tab'. I have the view filtered by a column named 'Facility' and it is all grouped by 'Tab'. I would like the 'Tab' group header to show even when the group is empty. How is the best way to go about this?
Comment: It seems that the limit occurs after the filter is applied. If no record is passed to the DVWP that has the group header, it cannot simply draw them from ether. I may need to look at passing a list of the 'Tab' Names and then creating a sub-view under each header.
Comment: Alternatively, I could put a file in the document library that is a place-keeper and have it skipped by if statement in the body of the XSLT?
Answer: The grouping is based on actual values returned (as you mentionned in your comment). So what you need is all the values of 'Tab' no matter what items are returned.
What I would do is make a custom list for your 'Tab' values and then create a lookup column. After that, make a linked source between my lookup list and the actual data. That would show all of the 'Tab' values and then show all items of the list filtered by that value, if any.
Comment: I'll outline what I ended up doing below. I forgot this question was here. Thanks for the bump!
Answer: Here is what I did to get the result I had requested:
I had established a DVWP that I grouped by a column named 'Tab'. I had the count of the node-set as part of eacah group header. The contents of this column read like this

Tab: 01 TAG's Policy Memorandum (1)
Tab: 02 EPCRA Tier II Letter (4)
Tab: 03 ECO Appointment Memoranda (3)

The rows then would be sorted by 'Title' or any other column as needed under these headers.
This worked well as long as there was an item in each node-set. As stated in the question, if the node-set was empty, no value is returned for the column and there is no group header. So I simply added row with a dummy value for each value of 'Tab'. I gave it a fairly obnoxious name that was not likely to ever be used as true value. I had the 'Title' valued as 'Placeholder to hold tab open' for each value of 'Tab'. I then modified the XSL Template SharePoint calls 'dvt_1.rowview' and nested the contents of this template in the follow if statement:
<xsl:if test="not(normalize-space(@Title) = 'Placeholder to hold tab open')">

This way only those rows that do not hold the sentinel value are rendered. This put the count off for the group headers as even though the row with the sentinel value was not rendered into HTML it was still part of the node-set. I fixed this at the point of the render for the group header.
In the XSL Template SharePoint called dvt_1.groupheader0 I modified the comparisons from count(nodeset) to count(nodeset)-1. This both fixed the counts in the header as well as allowed me to format "empty" group headers so they were more subdued than those groups with content important to the end user.
Perhaps not the most elegant solution, but it looks nice on the page.