Could electromigration cause a short circuit in a PCB

Question: Is it possible that electromigration cause a short circuit in a PCB? Theoretically  due to chemical potential difference between gold and nickel (1.68 V) it's known that metal ions can penetrate into the isolation and form a bridge. Is that really a practical threat and such a process is really causing short circuit in PCB devices? Is that process occurring only when the device is turned off? Could that make a short circuit between two close pads of a component for example a smd capacitor 0603?
Comment: For PCB level failure mechanisms, you might want to look into [dendrites](https://en.wikipedia.org/wiki/Dendrite_(metal)) and [tin whiskers](https://en.wikipedia.org/wiki/Whisker_(metallurgy)).
Comment: look into CAF..
Comment: You may find this [document](http://www.idc-online.com/technical_references/pdfs/chemical_engineering/Electromigration.pdf) interesting.
Comment: From the wiki article it looks like electromigration is a) mainly happening when high currents are present, so not when the device is shut off; and, b) more an issue in on-die interconnect than pcb level interconnect.
Answer: It is very unlikely that you would see real electromigration in something as "gigantic" (relatively speaking) as a PC board. We typically speak of electromigration at nearly microscopic dimensions (such as inside an integrated circuit).
OTOH, tin-whiskers are becoming a serious problem with the mandating of lead-free solder. ROHS is creating a whole new class of "planned obsolescence". In fact critical products (medical, aerospace, military, etc.) are exempt from the ROHS lead-free rules specifically because of the tin-whisker problem.
Comment: Most whiskering so far has been observed in pure Sn lead finishes, *not* in SnAg/SnCu/SnCuAg solder joints -- this means that we may see RoHS hi-rel if the industry can get their arses behind NiPdAu/Ni-barrier terminations instead of those blasted matte Sn ones.
Comment: "The Galaxy IV was a telecommunications satellite that was disabled and lost due to short circuits caused by tin whiskers in 1998. ...The manufacturer, Hughes, has moved to nickel plating, rather than tin, to reduce the risk of whisker growth. The tradeoff has been an increase in weight, adding 100 to 200 pounds per payload." - Wireless Week, May 1999
Comment: Then why, over 15 years after Hughes' switch to Ni-plating on component terminations, can I not get Ni-barrier or NiPdAu terminations across the board on components?  (ICs are hit-or-miss at best, discrete semiconductors are fugetboutit, and passives are fairly rare -- I've only heard of it on higher end chip resistors and caps)
Answer: If you have a mechanism for electromigration, than yes I suppose its possible. Possible mechanisms involve battery-like processes and\or an electric current. There are certain materials that develop "tin wiskers". If you are exposing your PCB to chemicals that could aid in the breakdown of metals and cause corrosion\reformation of a metal. If you have a really high current then this is also possible because you turn the metal into a plasma and it deposits elsewhere, like a sputtering machine. Metals don't move around on there own, they are stable, they need energy to move.
Keep in mind that just because its possible doesn't mean its probable. If you are having issues with shorting in a PCB I would first suspect the manufacturer, get an unpopulated PCB and inspect it. If its on the top layer then it should be easy to spot and measure on an unpopulated PCB. If its an internal plane sand off the problem area very carefully to expose the problem area (you can see through the PCB in a lot of cases by sanding off the solder mask, you can even sand through planes.)
If it is a problem then contact the manufacturer.
If your having an issue with a component, then it could be the assembly process. When you get your boards back from the assembly, do a visual inspection. Even better, pull the capacitor off the board and measure the impedance and make sure its open. Then put it back on the board and make sure there are no solder bridges.
If your having a cap short out, if it's a polarized cap, you probably have a polarity problem. Tantalum caps should be rated to ~70% of their working voltage. Ceramic caps voltage rating should not be exceeded. Keep in mind there is also esr in a cap, it is possible to have some self heating depending on the conditions.
Comment: Would a conformation coating remove 99% the electromigration?


Conquest narrows the peaceful fields

Question: I can't figure out the phrase «conquest narrows the peaceful fields» from the poem by Edna St. Vincent Millay. What does it means?
Comment: Sorry, but [Criticism, discussion, and analysis of English literature](http://english.stackexchange.com/help/on-topic) is off-topic here.
Comment: Poets are a strange species. We don't answer questions such as interpretation of their poems.
Answer: Narrows is likely being used in the sense of shrinks--it's an anti-war poem, so the observation is being made in that context (arrows shrink the peaceful fields in wartime). She was making a rhyme with arrows, so there is the chance she wanted a secondary meaning of arrows/narrow the soldier's life--whenever there is a rhyme in place within a poem, you should check to see the relation of the words and how they are being employed within the framework of the poem.

Make bright the arrows
Gather the shields:
Conquest narrows
The peaceful fields.
Stock well the quiver
With arrows bright:
The bowman feared
Need never fight.
Make bright the arrows,
O peaceful and wise!
Gather the shields
Against surprise.

Conquest narrows the peaceful fields


Virtualization of desktop

Question: I'm thinking about virtualization of my laptop(for educational purposes). My idea is to install very light host OS and have all the rest as virtual machines. Microsoft's Hyper-V Standalone would be very good solution, but it's impossible to access virtual machine from computer, where the Hyper-V is the host(isn't it?). So, which virtualization software would be good for me? I wanna have virtualized Windows 7(and maybe some other windowses). My processor support Intel Virtualization Technology.
Answer: If you have the money, you can always get Windows Server 2008 R2 full edition.
You can install Hyper-V on it and the way it gets installed, even if you have SQL and many other things running, it does not slow down the running Virtual Machines. (I forget the technical term of how it runs the primary OS).
Alternatively, you may like to simply run a standard desktop OS such as Windows XP or Windows 7 and optimise it using the guides at Black Viper then install a desktop virtualisation solution such as VMWare Workstation, Microsoft Virtual PC or Sun Virtual Box
Comment: I don't have money to buy full Win Server.I am alredy running Windows 7 with VirtualBox, but I'm wondering, if it is possible, to have faster VMs :).
Comment: @Agares - follow my link above to Black Viper, it has guides to tweak Windows for maximum speed.

Virtualization of desktop


Force laptop to use battery, not charger

Question: I was wondering if it was possible to force a laptop running Windows to use its battery as the power source even when a charger is plugged in?
If so, is it possible to switch between power sources programmatically?
Comment: Just out of curiosity, why?
Answer: Good question but the answer is very simple.
Few laptops are designed to use the battery only and few can also power on with AC charger.
Example:
1) AC Charger --> Battery --> Laptop motherboard
2) AC Charger --> Battery and Laptop motherboard
You can do a simple test:
Remove the Laptop Battery and only connect AC Charger and try to power on, see if it works. You can repeat this experiment with couple of Laptop models to get to know.
Comment: @ClassStacker, this questions is more of opinion based and have no specific answer as this differs from vendor to vendor.
Comment: I believe there's a bit more to the original question, b/c in your example 1), the battery will only be discharged a little bit and then charged again. I'm not so sure that's what the OP intended. Maybe the Q was more about being able to have a full discharging cycle while the charger is connected.
Comment: Not meaning to nit-pick but questions with opinion based answers should be closed instead of answered, and if you ask me, with only a limited number of meaningful hardware variants, there's nothing opinion based in sight here.
Answer: Windows does not support this natively. There are some laptops where software powermanagement software is shipped along with the laptop that offers control to do exactly what you request. It'll run from the battery disregarding the charger until a certain percentage has been met and then charges the battery again.
One brand I know that does this is Lenovo. I don't know if all their laptops have this function, but I've seen it on one and played with it. The biggest concern with this feature was, that when it switches to battery power, it also wants to do power management functions, such as: not use the CPU and GPU fully, so playing fast games was not practical. In the end, we decided to not use this functionality for the following reason:
If you want to wear down the battery less because you will mostly be running on AC power, simply consider removing the battery altogether and only use it with AC power.
If you want to be able to have the luxury of continuing to work while there is a power outage, you will need to have the battery inserted all the time. You might want to consider purchasing a 2nd battery and just let the current one wear out. You can change batteries if you want to actually use the battery on its fullest.
Note that I always use my laptop with charger and my battery has worn out a bit, and still I have over an hour of battery usage on a full charge.
A bit more related to your question: Windows cannot do it, but there might be software available that can do it. I don't know software that offers this though, and SuperUser is not about requesting software packages either, so I can't help you on that part, but google might help you find a suitable software package. You would want to look for Powermanagement download battery something along these lines.
Comment: 2 downvotes? Anyone care to explain why?


UpdateSingleSalesforceObject for custom object

Question: Good day to everyone!
I wonder is it possible to make UpdateSingleSalesforceObject of custom object, where Id is in the field with DataType Lookup(Contact)?
Thank you in advance and have a nice day!
Answer: Yes, it should be possible but might depend on your implementation approach. Just go through the UpdateSingleSalesforceObject guideline to make sure you would build the correct function and remember couple more points:

Include all mandatory fields for the update
If you have to include Date datatype fields, you would need to convert it to the correct format -

SET @time = FormatDate(Now(), "iso")

Certain Salesforce objects enforce record-locking when a record is modified, to ensure the referential integrity of data. This applies to records that have a relationship to lookup records in a different object. If the function is used to asynchronously update multiple records (for example, the function is included in an email) and the object has lock contention, the records may fail to update.
Comment: I got such Error
Error Message: "Call to update the salesforceobject Consent__c ID = 0033j00003oWipCAAS failed! Error status code: INVALID_ID_FIELD\nError message: '0033j00003oWipC' is not a valid Salesforce ID for the type Consent
It looks like that 3 last characters from Id were deleted. Should I use 15 characters instead of 18?
Comment: No, 18-characters format should be sufficient, yet I would assume you are using incorrect either ID value or field that correlates to the ID.
Comment: Thank you. You were right, I tried to use ID of the Contact, not of the custom Object.


How do I check if Vim is currently recording a macro?

Question: Is there a way to programmatically check if Vim is currently in the recording mode triggered by q?
Answer: Since Vim 8.1-0020, there is a reg_recording() function that'll return the name of the current register being recorded. An empty string is returned if we are not recording.
Comment: @ChristianBrabandt. Well, it depends if the script needs to target older versions of Vim. In that case, statox' solution may be the only workaround available.
Comment: That is the correct answer.
Comment: Why is vim using underscore notations for new functions? Isn't underscore notation deprecated in vim (I noticed a lot like `buffer_name()` is replaced by `bufname()`)?
Comment: @wengwengweng you should ask such questions on vim-dev mailing list
Answer: Edit I wasn't aware of reg_recording() but if you have a newer version of Vim Luc's answer is clearly the best answer.
I'm not aware of a built-in way to check if Vim is recording but you could use the following workaround in your .vimrc:
let g:isRecording = get(g:, 'isRecording', 0)
nnoremap q :let g:isRecording = !g:isRecording<CR>q

The first line will create a global variable g:isRecording which is falsy by default or takes its existing value if you re-source your .vimrc.
Then you remap q to toggle the value of g:isRecording when it toggles the recording mode and you can then test g:isRecording.
That's not the most elegant solution but as :h recording doesn't seem to mention a variable which would change with q and :h autocmd-events doesn't mention an event related to recording, I guess that the easiest way to do.
Comment: I'm curious. Why have you preferred to define an autocommand to initialize the global variable instead of setting it in the vimrc? (with `let g:isRecording = get(g:, 'isRecording', 0)` to permit to source the vimrc as many times as we wish)
Comment: @LucHermitte It was because I didn't think of resourcing the vimrc :)


Is FIELD COLLECTION VIEWS module only for showing data in table format?

Question: I am using field collection module and in search of formatting it I came across field collection views module. But whatever tutorial I came across, in all it is display data in Table form only. Is there possibility that we can use field collection views module as Views module so we can have lots of option for formatting? Or Field collection views module is limited to show data to Table format only?
Answer: At admin/structure/types/manage/[node-type]/display/full changed the view mode for my field_collection where format = "Table of field collection items". The view mode setting is ignored, as viewing the original node still shows all fields as configured in the "Full content" display mode.
field_collection_table.patch


What is the verb form of newsjacking?

Question: What is the verb form of newsjacking? Can I say I'll newsjack on his divorce and make some money. I can't find this in the dictionary, though. Could anyone give me some suggestion? Thanks.
Comment: I'm a native speaker, and I've never heard the word "newsjack" before.
Comment: Just thinking in terms of grammar, if a word has an *-ing* ending, then you are looking at the gerund or participle of a noun, and the base form of the noun is *usually* whatever is left after you remove *-ing*: stretching -> stretch, yawning -> yawn, etc. So yes, the bare infinitive would just be "newsjack".
Answer: "Newsjacking" is when a brand or firm mentions or creates a campaign centred around a major, well-discussed news item.
So for your example to work, "his divorce" would have to be a well-discussed news item. And you would have to be a brand or firm.  You would say "newsjack his divorce" by analogy with "hijack his aeroplane".
Newsjack is a very recent word, and only really has currency among internet advertisers. It isn't in general circulation.  Standard dictionaries don't (yet) include it.

What is the verb form of newsjacking?


Relationship Between Watts and Candela

Question: I am currently working on a project that involves the use of LEDs. According to the datasheet, the LEDs I am using have a maximum brightness of 10,000 mcd. In my project, though, I will not be using the LEDs at full power. I was wondering how reducing the power would change this brightness measurement of the LEDs. I know that this will decrease the brightness, but by how much? For example, if I were to double the resistance of the LEDs while maintaining a constant voltage (cutting the power in half), what would the brightness be? Is there a formula/law that could be applied in this situation?
Answer: Under the assumptions that (i) the efficiency of the LED doesn't change with load, and that (ii) neither does the spectrum, its luminous intensity (what you refer to as 'brightness') is proportional to the power it draws. Therefore, if you cut the power in half, the luminous intensity will be half as bright.
(However, you should keep in mind that human vision is not necessarily linear, and humans will not necessarily perceive a decrease by half in the luminous intensity of a source (i.e. its rating in candelas) as a decrease by half in brightness. Here, though, you go into more subjective regimes of how the human eye and brain respond to stimuli.)

Relationship Between Watts and Candela


Only one thumbnail for all photos

Question: I downloaded the million moments app which basically makes a cool album from the photos you choose. The problem is in the import screen when I choose photos, all the photos just have the thumbnail of one of my photos. Now this is a headache because I can't pick the photos I like and I have to resort to picking the whole folder. I just discovered today that even the Flickr app has this problem. Now I think I'm sure my phone is at fault, my question is how do I fix this? Even with the media rescans the thumbnails still aren't correct and just shows 1 of my photos. Quickpic and the stock gallery don't have this problem though. Any ideas what's wrong?
Answer: When I had this problem it was caused by a corrupt SD card, so you should check that out soon: the longer you leave it, the more likely it'll corrupt a file you don't have a backup of.
For now, try clearing the cache of any app that shows the problem (from Settings → Apps). If that doesn't help, clear the data of the Media storage app, from the same screen, and then reboot the phone. The Media storage app is responsible for indexing your photos and music and letting apps search them, so clearing its data often helps fix problems with the photo index, such as broken thumbnails.
Comment: I think I can rule out the media storage and the corrupt SD card. I tried the first many times because even my mp3s have duplicated names, and it didn't work. For the corrupt SD card I had an SD card before and I tried the app there, it had this thumbnail problem. I gave the SD card to my sibling who has a Samsung phone and the app works perfectly on that phone with my old SD card. Guess the only thing left to do is to clear the cache of the app that shows the problem. I'll come back with the result.

Only one thumbnail for all photos


Show every nonempty compact Hausdorff space is not the countable union of nowhere dense sets

Question: I know this proof is somewhat similar, or related to the Baire's Category Theorem but I can't seem to figure out how to do it.
The Baire Category theorem asserts that if X is a complete metric space or a locally compact Hausdorff space (my case), then the complement of a countable union of nowhere dense sets is always nonempty.
How can I use this on the proof?
Answer: Since every compact Hausdorff space is locally compact, you can actually use the statement that you mentioned.


How does one target a piece of jewelry being worn by a character?

Question: I (the GM) currently have a wizard in my campaign that was able to nab an amulet that controls a shield guardian. If an enemy were to make an attempt to break the amulet's chain so that it was no longer being worn (thereby causing the wizard to lose control of the shield guardian), what would the mechanics be for that? Would they make an attack roll against the wizard's normal AC, or would the AC be higher since it's a smaller, more specific target?
Answer: Objects have HP and AC
According to the rules as they written.  Objects have an AC and HP like characters do.  So you can make attacks against items.

Object Armor Class

Substance   AC0
Cloth, paper, rope  11
Crystal, glass, ice 13
Wood, bone  15
Stone   17
Iron, steel 19
Mithral 21
Adamantine  23

Object Hit Points

Size    Fragile Resilient
Tiny (bottle, lock) 2 (1d4) 5 (2d4)
Small (chest, lute) 3 (1d6) 10 (3d6)
Medium (barrel, chandelier) 4 (1d8) 18 (4d8)
Large (cart, 10-ft.-by-10-ft. window)   5 (1d10)    27 (5d10)

There is no reason you couldn't use the standard grappling rules against a worn object (Grapple specifically mentions creature, but the mechanics could just as easily apply to objects as they already have AC to test against); possibly with disadvantage for movement or AC bonus for cover.
I, personally, would likely also make breaking the chain a subsequent athletics check or attack on the next turn, so that the player has a chance to attempt to stop the effect between you getting ahold of the item, and breaking the chain.
Or, Follow the Example of the Ioun Stone
The Ioun Stones have very specific rules about being taken or being broken.  You could just adapt them to your necklace.

...must use an action to grasp or net the stone to separate it from you, either by making a successful attack roll against AC 24 or a successful DC 24 Dexterity (Acrobatics) check. You can use an action to seize and stow the stone, ending its effect.
A stone has AC 24, 10 hit points, and resistance to all damage. It is considered to be an object that is being worn while it orbits your head.
Comment: I like the Ioun Stone comparison.
Comment: Although I like your answer a lot, it should be noted (since you specifically said RAW here) that Grapple in fact does not allow for objects to be grappled RAW "When you want to grab a **creature** or wrestle with it, you can use the Attack action to make a special melee attack, a grapple.". You may want to make a note of this and/or remove the RAW part if that makes sense to you.
Comment: I thought about the amulet's AC and HP, too, both of them being 10 according to the MM's shield guardian entry. But I was hesitant to make this the bar I set for hitting/taking it because objects being worn seem to follow different rules than ones that are just lying about (and I would imagine the amulet's 10 AC is when it's just lying about). But I also like the Ioun Stone idea after looking into them a little more, so I may do that. Probably with a Dexterity check/save/contest added to see if it hits first. Thank you!
Comment: Ah, good point.
Comment: The difference with the Ioun stone is that it is floating in air near you, not actually worn or secured. A better comparison would be to look for some sort of pickpocketing or similar ability to grab it or the sundering rules.
Comment: Yes, the Ioun stone is different in that respect.  But reusing the concept isn't a bad mechanic.  The Ioun circling could actually make it harder to grab than a chain just hanging around someone's neck...  Pickpocketing is typically a Slight of Hand check contested against preception (at least in my games, and Matt Mercer does it that way on Critical Role)  because you're trying to conceal it.  It shouldn't feel like a stealth check to me, unless they are trying to be sneaky.  It feels like a strength (Strength or attack breaking the chain) and/or aim thing (Dev, Str or grapple like roll).
Answer: Use an Improvised Action
You do this by using the Improvising An Action rules, which exist to cover everything that isn't covered by a specific action. You can use it to resolve an "I snatch the amulet" or "I break the chain" attempted action. You'll find them in the inset box at the top-right of page 193 of the Player's Handbook. These rules refer to the DM telling the player what to roll — as DM, you'll be referencing the general guidance in the DMG in the Using Ability Scores section that starts on page 237.
Basically, the Improvising An Action's rules point that "The only limits to the actions you can attempt are your imagination", and D&D 5e's emphasis on simplicity and speed, means that you pick an appropriate ability score, set an opposed target (either a DC or an ability score roll made by the target), and then roll 'em to see if it worked. Advantage and disadvantage as usual are applicable, and for such a specific and small target, probably relevant.
PCs can do what NPCs can do
As a bonus, using the improvised action rules will show them off to the players. Perhaps they thought their only options were the actions listed in the PHB! Seeing the amulet snatched may inspire them to start doing more varied things during combat — which will make fights in your game more dynamic, creative, and interesting.
This also gives you a way to judge how hard it should be for your NPC: how hard would you want this maneuver to be if the PCs tried it? So make it neither too easy nor too hard, and it will improve your game in the long run (even if the NPC's snatch attempt fails!), because it will enrich your players' imaginations.
(To that end I would personally rule this an opposed Dex vs. Dex roll, but with disadvantage to the snatcher due to the small size of the target. That means it has a small chance of success against all but very clumsy opponents, which seems about right. It also fits the "value" of the attempt as very high: a risky, low chance of success, but with a high payoff is a nice balance.)
Comment: I'm fine with that (I've never subscribed to the "equipment is part of the character" philosophy in D&D games, since unlike some games, D&D doesn't make that an actual rule), but that's good to note for a more general audience. (If/when that comes up in *my* game, that would just mean PCs start protecting their component pouches better!) It makes sense that if fighters can be disarmed, so can wizards (albeit with more difficulty).
Comment: Slippery Slope Warning: This could easily move into Improvised Actions to remove a focus/component pouch. Cool in theory, but once your PC Casters it can be used against them (which will be much more frequent than them going up against Casters) and that they can't cast spells with M Components, they may wish that door wasn't opened.
Comment: @MarkBooth A good point; I've updated the answer!
Comment: Yo sure about that first word? Nice answer though.
Comment: @ClearlyToughpick Oops! Thanks. Next time feel free to edit any obvious typos. :)
Answer: D&D 5e (and previous versions, for that matter) has no mechanism for such specific targeting.  It has always been assumed that a person's carried belongings are (perhaps even magically) a part of him, and if the character survives, his stuff survives with him, almost always.
So, that being said, snatching an amulet from an active person is not something there is provision for.  To target the amulet without breaking the spirit of the game will require that the mage be rendered in a condition of unconscious, paralyzed, or at the very least, restrained, such that the amulet can be removed from his person.
Comment: I don't think it is fair to say that allowing the targeting of item is "breaking the spirit of the game" at all. There are many things not explicitly written into rules, but nothing I have seen says that it runs counter to the intent of 5e to allow it. Indeed, they seem to openly encourage DMs to actively enable these types of actions not covered by rules.
Comment: It has always been assumed that a person's carried belongings are (perhaps even magically) a part of him, and if the character survives, his stuff survives with him, almost always.
Answer: Treat the amulet as different entity that can be attacked.
This is how I will determine the DC (instead of AC):

The amulet is unlikely to be kept within armor, so it does not benefit from armor AC.
The wearer can try to evade the attack, so it will benefit from DEX modifier when wearing armor. So if the target wear a medium armor, it will have +2 maximum.
Because he is targeting a specific part of the "body", increase the DC by 5.

For example with +2 DEX, that makes the DC = 10 + 2 + 5 = 17
This is how I decide if his attack successfully hit the amulet:
Do attack roll with disadvantage. If the attack is successful against the DC, then the amulet is destroyed. If not, then use the disadvantaged attack roll to attack the target character as usual with their AC.

You missed the amulet by inches, but your sword barely managed to land on his shoulder instead.

You do the attack with disadvantage because you aim for specific part instead of freely looking for openings.
Comment: This is very much a house rule and should be marked as such.
Answer: In my campaigns, when the PC's target an item, they have to make a dexterity check to see if they hit it. If they hit, they make a normal attack against the item, including the item's AC. Assuming the item is being worn, such as an amulet, it should be assumed that the person wearing said item should be hit by the attack as well. Therefore, the PC makes a standard attack against the wearer, including the wearer's AC. Items may be large enough to grant the wearer additional protection, such as granting additional AC to the wearer, but such things are totally up to the DM.
The principle of attacking an item worn or otherwise attached to a player can also be applied to ropes or chains that restrain or bind a character. Players should take disadvantage to hit the person that is restrained, since, chances are, they're trying to free them without harming them. The disadvantage represents the possibility of a player slipping up, and accidentally harming the character they are trying to free.
In one of my campaigns, one of my players put on a suit of armor that was, unbeknownst to him, cursed. The armor trapped him inside, and made him immobile. Another player attempted to attack the armor in creative ways as not to harm the player wearing the armor. They eventually destroyed said armor with minimal harm done to the player that was wearing it.
Comment: How does this work out?
Comment: If they target the item, they have to make a dexterity check to see if they hit it. If they hit, they make a normal attack against the item, including the item's AC. Assuming the item is being worn, such as an amulet, it should be assumed that the person wearing said item should be hit by the attack as well. Therefore, the PC makes a standard attack against the wearer, including the wearer's AC. I mentioned that an item may be large enough to grant additional protection, but such a thing is totally up to the DM's discretion.
Comment: Cool! Could you describe that in the answer? We look for people saying "here's what I've done" to also say how it worked out in practice at the table, because it helps us distinguish things that only seem good in theory from things that work well in practice.
Comment: Your second paragraph seems to largely repeat the first. I'm not sure if you're saying anything new in the second one. Can you edit to make the whole answer clearer please.
Comment: The second paragraph was intended to reiterate and further explain the first, however I agree that it was confusing and therefore deleted the first, favoring the second. Additionally, I expanded on my example for chained/bound characters, as well as provided an example from my campaign.


Facebook Authentication and HTTPS - domain, ports, protocols must match

Question: Seem to be having problems on my website since changing over to HTTPS.
If a user adds something to cart, and is on the checkout page and
 - logged into Facebook already
 - authorised with the app already
Clicking on the Facebook Login button will work - no problems.
If a user adds something to cart, and is on the checkout page and
 - not logged into Facebook already
 - previously authorised with the app
Click on the Facebook Login button will make the pop-up open, prompting their login details. After successfully being logged in to FB (checking by opening a new browser window) - I get this error in the console - this is what I guess is stopping it from working.
Note - this work perfectly in http..
Unsafe JavaScript attempt to access frame with URL https://www.facebook.com/dialog/permissions.request?_path=permissions.request&app_id=115551305199328&redirect_uri=https%3A%2F%2Fs-static.ak.facebook.com%2Fconnect%2Fxd_arbiter.php%3Fversion%3D11%23cb%3Df368597038%26origin%3Dhttps%253A%252F%252Fwww.iloveugly.net%252Ff21427b398%26domain%3Dwww.iloveugly.net%26relation%3Dopener%26frame%3Df280a13e4&sdk=joey&display=popup&response_type=token%2Csigned_request&domain=www.iloveugly.net&perms=publish_stream%2Cuser_likes&fbconnect=1&from_login=1&client_id=115551305199328 from frame with URL https://www.iloveugly.net/View-your-cart-content.html?page=shop.cart. Domains, protocols and ports must match.
from script connect.facebook.net/en_GB/all.js:78
website:
w w w . i l o v e u g l y . n e t
facebook app settings have the domain as the www.domain.net and the app URL as https://
Question: Why would I be getting this error, and how can I resolve it? Where can I look?
Comment: And what exactly do you want from us?
Comment: Sorry, Why would I be getting this error, and how can I resolve it? Where can I look?
Answer: Check how you have set up your successful-login redirects. They should be also pointing to https.


Can I flash same model but different operator firmware

Question: If I flash Telus SM-G920W8 firmware on my Bell SM-G920W8 device would there be any incompatibility issues?
Answer: The frequencies are the same from what I just looked up I have put v410 att firmware on my uk410 and it work but I never had mobile data on it so I'm not sure about data but I'm going to say your good to do it just proceed with caution have the correct firmware that's  supposed to be on the phone and if u have a custom recovery make a back up and give it a try I'm not saying it will work but it's a possibility and if other dont work try a custom ROM for the firmware you want to use I tried downloading and installing the stock AT&T firmware online UK 410 and it wouldn't work but cyanogen14 for the v410 flashed just fine to my uk410
Answer: In stack exchange's infinite wisdom, I can post answers, but not comments. So what follows should be a comment, but blame stack exchange, not me:
You won't run into incompatibility issues with Android. The phone will function, since that's the exact hardware that ROM is supposed to run on. It's been a long time since I've ran a carrier's ROM or had a locked phone, but you should be able to add the APN for your carrier in the data settings and it'll work on that end too.


Overstaying In Philippines

Question: Overstayed in Philippines for 18 years. I wanna go back in Hawaii. But i have no money. Also my passport lost 3 years ago. I don't know what to do. Not enough money to go home.
Answer: You have to approach US embassy in Philipines and explain the situation. US embassy can help you getting a new passport and emergency loan to repatriate you back to USA.
But rest assured that you have to pay the amount back and US might restrict you from leaving USA until you paid back the amount.
Comment: but what about the money..? not enough money to get a new passport and for a flights
Comment: @AliaMoral Anish Sheela's answer covers this issue in its second sentence. The US Embassy in the Philipines can make or arrange funding to pay for your return.
Comment: and the cost of overstaying..?
Comment: @AliaMoral US government will loan you money for that. Contact your embassy. Never contact Philippines authority now.
Comment: See - https://travel.stackexchange.com/questions/79004/overstayed-in-the-philippines-for-years-how-to-go-back-to-the-us-without-paying?noredirect=1&lq=1
Comment: https://fam.state.gov/fam/07fam/07fam0370.html
Answer: You have a big problem.
You'll be referred for deportation (Source), but that is the least of your worries.
The fine for overstaying is PHP500 per month. If you have overstayed 18 years the fine will be over PHP100,000 (one hundred thousand); about US$2000. There will also be some administrative charges but they're small by comparison.
If you can't pay the fine you'll be detained until you can.
Contact the US embassy and ask for advice. Obviously you'll need to renew your passport. They might be able to help with the money, but dont count on it.
I suggest you don't contact the Philippines authorities until you have money to pay the fine. Things will be much more difficult to resolve from prison.
Comment: but not enough money to renew my passport and the flights..
Comment: @AliaMoral US government will loan you money for passport, flight and possibly to pay fine also. Contact embassy and embassy only.

Overstaying In Philippines


Norse god/goddess of law or justice

Question: Is there a Norse god/goddess of law or justice? Or is law/justice a too western of concept to have back then?
Comment: The concepts Law and Justice are pretty darn closely related. Are you suggesting that the Judiciary has nothing to do with law? It's stated purpose is to interpret and apply the law. It's full of *law*yers who went to *law* school, and work for *law* firms, representing clients in courts of *law*.
Comment: Law and Justice are two unrelated concepts.  That is why the Legislature and Judiciary are unconnected in Western democracies.  Or are you suggesting that they were combined by Norse myth?
Answer: Yes!
Tyr was a norse God of law and war. Evidence suggests that he was once head of the pantheon, but was supplanted by Odin and Thor. He was wise and brave, the only of the gods courageous enough to offer his hand as collateral when they wanted to bind Fenris.
Forseti, the son of Balder, is mentioned by Snorri as a good mediator and judge. His name also means "the presiding one", so he has been linked with law and justice by scholars.

Norse god/goddess of law or justice


Different Activities for every level?

Question: So I've got a simple game with different levels. For the most part the levels use the same code, with only slightly different things.  Do i have to make a new Activity for every level?  The app will have a 'level select' screen.  Is there a way to tell one activity to run a certain set of java based on what level I selected? Any suggestions would be appreciated.
Answer: Perhaps activities can inherit from different "gameplay" classes using a common interface? Multiple inheritance could be useful here. Then you assign an activity to a level and get the gameplay.
Answer: I've figured it out.
On the level picking activity, basically have an Intent that can send information to the activity that actually runs the game.  Based on what level is selected, you can set it to change a string to whatever level it is. The gameplay activity will get the information from the level selection activity and use it to choose which "game" (lines of code) to run.
For example:
<code>if  (level.getString("level", "").equals("1")) {
                        //change aspect of game like time or the score: each of those
                        would be a Double
                    }
if  (level.getString("level", "").equals("2")) {
                        //change the time or score to be harder than the level before.
</code>

Different Activities for every level?


Multiple Deselection of rows in datagrid is not working with ItemRenderers in Flex

Question: I have an advanced datagrid.I used itemrenderers for each cell to display text with image.Now when i try to do multiple selection of rows using ctrl key its working fine but when i try do the deselection by using the ctrl key on the selected row all selected items are getting deselected and only the one which i clicked is highlighting.This is not the right behaviour when compared to the datagrid multi selection of rows without itemrenderers.When i click on non itemrenderer cells deselection of rows is working perfectly where as deselection of rows with itemrender are not working as expected.Can any one pls tell me how to fix this issue.
Thanks
Comment: There is no such thing as a "non itemrenderer": every cell is an ItemRenderer. Assuming you mean that it doesn't work correctly with your custom ItemRenderer, you should show us its code.
Answer: Got the solution for the problem.I used itemrenderer along with itemeditor and activated edit after double click. when we select multiple rows with ctrl and deselect each item its not working because of itemeditor. so i checked if ctrl key is pressed then i made datagrid.editable to false else i made editable to true. Now i am able to do deselection of rows perfectly.


Why is chromium involved in oxidation of alcohol?

Question: Like what is it about chromium atom that make them able to oxidize atoms? Like can't any other transition metal like manganese, mercury among several others do the same thing? I always see example of chromium in oxidation of alcohol and i ws curious why? Thanx.
Comment: Manganese is also another notable element which has ions that can catalyse oxidation. And strictly speaking, it is the related ions that do the oxidation, not the atoms. As to why this happens, have a look at their half reactions and oxidation states.
Comment: Chromium used in the type of chemistry you're talking about is in a +6 oxidation state and can readily accept electrons. Manganese in the form of permanganate (+7 oxidation state) doesn't a great job of oxidizing alcohols though the oxidation is less controlled can leads to by-products that may include some cleavage of adjacent carbon-carbon bonds. Chromium just happens to balance reactivity with selectivity.
Answer: Chromium is hardly the only element that is used to oxidise alcohols. Alcohols are really easy to oxidise and apart from chromium, you can also use manganese ($\ce{MnO4-}$ or $\ce{MnO2}$), ruthenium (TPAP), iodine (DMP), sulfur (Swern oxidation and variants), even nitrogen works (TEMPO), and in the Oppenauer oxidation carbon is formally the oxidising agent. The list really does go on, this is just the tip of the iceberg! In all of these reagents the element I named is the one that undergoes reduction.
The only criterion is that, well, it must be an oxidising agent. So, for example, you would probably be hard-pressed to find a calcium-based oxidising agent, since $\ce{Ca^2+}$ is pretty happy being $\ce{Ca^2+}$.
The issue is: saying that "chromium" is involved is a little misleading. Chromium metal is not a very good oxidising agent; neither is Cr(II), and Cr(III) not quite either. You can dump all the $\ce{CrCl3}$ you like into an alcohol, and you probably won't get any ketone. ("Probably" because who knows, you might very well get some ketone if you leave it open to air, since molecular oxygen is a pretty good oxidising agent. There was a slightly infamous incident several years ago where a lab claimed to have discovered a NaH oxidation of an alcohol to a ketone; it turned out that they didn't exclude oxygen thoroughly and that was what was causing the oxidation.)
It's always chromium(VI) that is in the oxidising agents. $\ce{CrO3}$, PDC, PCC, ... all have chromium in the +6 oxidation state. That's strongly oxidising and that's why it sees use as an oxidant. However as said earlier - it's hardly the only element used.


Does it improve my credit if I pay my credit card bill off several times a month as I use it?

Question: I have a secured credit card of $200, if I used 30% (about $60) in the first time and pay my credit card balance in full after one week, then spend another $60 and pay it after a week, and continue in this way for using $60 and paying it for 4 times in one month is better to build a credit, or if I spend $60 and wait for due date and pay it before 30 days????
Comment: It does not matter. All that matters is that you pay it on time in regards to building credit
Comment: Additionally, credit score has no memory when it comes to balances. A loss in point due to high utilization one month is wiped away when you pay it off the next month. Be responsible with your debts and your credit profile will benefit
Answer: Paying your outstanding balance multiple times during the billing cycle will not impact your credit score. There is no benefit to doing this from a payment history perspective. The credit company looks at the balance on the statement they send and whether that payment is late or not.
One benefit you may find to your credit score by paying more often is that it will keep your credit utilization percentage lower because you will be reducing your balance more often.  Unless you run your available credit up close to the limit regularly during the billing cycle so you are showing near 100% utilization, the benefit you get from this may not be worth the extra effort.
Answer: To my knowledge, only paying the bill that you are assigned for each period will build credit. That is to say, if you spend $200 in one month, and they ask for a payment of $25, only making sure you have paid that amount will have any direct impact on your credit.
Buying and paying off the card immediately is a good practice, and will keep you from building any debt, but it won't increase your credit score by simply repeating the process over and over during a single billing period.
Answer: Always be aware of your credit utilization rate, which is not reported at the same time as your statement is generated.  Several of my cards seem to update utilization at least once a week, according to the credit monitoring services I use.  Carrying a high utilization rate (especially more than 30% of your limit) is not a positive thing for your short-term credit.
Keep in mind also that your credit card issuer will report your highest balance too, so that has something of an impact as well.  In other words, if you were to use $150 of your $200 limit, the card issuer will report to the bureaus that at one point you were using 75% of your available credit.
Paying your bill more than once a month does nothing to help your credit, because the card issuers will only show one payment on your account when they report.  It does help you keep your balance lower, which improves the utilization rate and leaves you room on the card in case of unexpected/emergency needs.
If your secured card is like most then you can increase your limit by adding to the savings account the card is tied to.  It would be well worth it to you to send maybe $20 a week or so to raise your limit so that a $60 purchase has much less effect on your utilization rate.
While having a secured card does help build your credit somewhat if you make your payments on time, having a low limit is a bit of a negative, so you want to see if you can get it increased.  Some banks, after 6 months of on-time payments, will be willing to talk to you about raising your limit without it being secured, while others will make you wait a year.  If you want to do it any sooner, you'll have to send in money to your savings account.
I hope this helps.
Good luck!


Collaborative translation tool

Question: Do you know any collaborative translation tool?
I've seen the suggestions in this answer, but I'm specifically searching for a tool to translate books (so large documents made of paragraphs, mostly), with possibility for other users to check/correct/validate other users' translations, roles (admins, validators...), and if possible something that has a nice API so I can convert the result into LaTeX to publish the book.
The tool could be SaaS (preferably free) or open-source (to be hosted on LAMP or similar).
Answer: I recently know this project - Narro.
It seems an open source collaborative translation tool.
It only needs a server with PHP and MySQL to deploy.
Haven't tried it out but I think it should be something that you are looking for.
Otherwise there is another website of collaborative translation:
https://crowdin.net/
I'm not sure if it meets your need but I think it's worth to try.
Answer: I have been working with a really useful collaborative translation tool, http://poeditor.com/. It allows you to create as many projects as you wish and make them public for contributors to join and translate for you. Contributors can collaborate on translations with no limits and the work space is really nice and simple to use.
Answer: Translating text
Services
http://Duolingo.com
If you are willing to release the text under a CC like licence and if you are translating between English and Spanish, Italian, German and few other large European languages, and if you are OK with that you cannot dictate who can and who cannot edit the translation, you can try uploading it for the Immersion feature on duolingo.com language learning site.
Google Translator Toolkit, http://translate.google.com/toolkit
From a cursory look I figured it is impossible to make the translation editable to everybody, you need to grant the edit right to particular Google Account holders. That is bad for me, but others can be OK with that.
Self hosted
Translating software
These tools work with po files.
Services
http://poeditor.com/
http://weblate.org/hosting/
http://www.transifex.net
It provides automatic similarity search in already translated strings, allows some forms of communication between the translators, has support for some simple validation (warns if the translation is wildly different from the source string) and so on. For a demo, you can take a look at for example the Universal Subtles project there.
https://crowdin.net/
http://pootle.translatehouse.org/
Self hosted
https://code.google.com/p/narro/
http://pootle.translatehouse.org/
http://weblate.org/

Collaborative translation tool


Standard AMS-Sum Operator using MnSymbols?

Question: Because a professor who reads one of the lectures I attend this term writes so slowly, I typeset a lecture script for that lecture in TeX. For the use of some symbols and for better underbrace rendering I use MnSymbol. As those of you who are familiar with MnSymbol may know, it offers a different sum operator than the amsmath-package. It also offers a different integral operator, but I already fixed that by loading "esint" as last math font package, as I like those amsmath math operators better.
Is there a way of easily "fixing" the sum operators to be the standard ones without having to stop using MnSymbol? Any help would be appreciated.
Comment: If you have a small set of symbols from MnSymbols to use, it is relatively easy to do. Is that the case?
Comment: Yes thats the case, its mainly \(big)cup dot and the braces from MnSymbol. What does the trick then in this case? Thank you in advance :)
Comment: this question may help if you want to use just a few symbols from "another" font: [Importing a Single Symbol From a Different Font](http://tex.stackexchange.com/q/14386)
Comment: Ok, so I'll have to find out how the syntax is for importing the sum operator from amsmath. I'll try this by myself, if I don't succeed I'd be glad if one of you could help me.
Comment: I did not find sny table whatsoever which showed me the name of the \sum operator in amsmath, I do not know how to achieve this by myself. Please help me.
Answer: See FOLLOW UP below for importing CM symbols into MnSymbol.  But first...
Import MnSymbols:
If you only use a few MnSymbols, it is easiest to import just those, rather than loading MnSymbol package.  Here is how it is done (I used, for MnSymbol specific reference, Dashed left arrow over symbol, though other questions on this site about importing symbols are also useful).
It helps to look through the MnSymbol package document (or better still, mnsymbol.sty) to find from which font family the symbol derives, and then it helps to use \fonttable (package fonttable) to display the font family in a table, from which you can determine the slot number corresponding to the desired glyph.
First, to determine font families, I look through mnsymbol.sty for the glyph name, and use it to determine the font family:

From the above pictures, I see that the \bigcupdot glyphs (\displaystyle and\textstyle) are \mathops and come from the symbols font.  The name symbols is associated with MnSymbolF font family.  These are needed in my MWE.  The \cupdot glyph comes from a different font family (MnSymbolC).
In the MWE below, I show the importation of 3 glyphs from two different font families: \cupdot, \tbigcupdot (textstyle \bigcupdot) and \dbigcupdot (displaystyle \bigcupdot).  I then use \mathchoice, to tell LaTeX to use the proper bigcupdot style in the appropriate math style.
If you uncomment my commented lines concerning fonttable, you can see the font tables from which I determined the glyph's slot numbers.
\documentclass{article}
% =============================================
%Import symbols from font MnSymbol without importing the whole package
% =============================================
\DeclareFontFamily{U} {MnSymbolC}{}

\DeclareFontShape{U}{MnSymbolC}{m}{n}{
  <-6> MnSymbolC5
  <6-7> MnSymbolC6
  <7-8> MnSymbolC7
  <8-9> MnSymbolC8
  <9-10> MnSymbolC9
  <10-12> MnSymbolC10
  <12-> MnSymbolC12}{}
\DeclareFontShape{U}{MnSymbolC}{b}{n}{
  <-6> MnSymbolC-Bold5
  <6-7> MnSymbolC-Bold6
  <7-8> MnSymbolC-Bold7
  <8-9> MnSymbolC-Bold8
  <9-10> MnSymbolC-Bold9
  <10-12> MnSymbolC-Bold10
  <12-> MnSymbolC-Bold12}{}

\DeclareSymbolFont{MnSyC} {U} {MnSymbolC}{m}{n}

\DeclareMathSymbol{\cupdot}{\mathbin}{MnSyC}{60}
% =============================================
\DeclareFontFamily{U} {MnSymbolF}{}

\DeclareFontShape{U}{MnSymbolF}{m}{n}{
  <-6> MnSymbolF5
  <6-7> MnSymbolF6
  <7-8> MnSymbolF7
  <8-9> MnSymbolF8
  <9-10> MnSymbolF9
  <10-12> MnSymbolF10
  <12-> MnSymbolF12}{}
\DeclareFontShape{U}{MnSymbolF}{b}{n}{
  <-6> MnSymbolF-Bold5
  <6-7> MnSymbolF-Bold6
  <7-8> MnSymbolF-Bold7
  <8-9> MnSymbolF-Bold8
  <9-10> MnSymbolF-Bold9
  <10-12> MnSymbolF-Bold10
  <12-> MnSymbolF-Bold12}{}

\DeclareSymbolFont{SymbolF} {U} {MnSymbolF}{m}{n}

\DeclareMathSymbol{\dbigcupdot}{\mathop}{SymbolF}{35}
\DeclareMathSymbol{\tbigcupdot}{\mathop}{SymbolF}{34}
\def\bigcupdot{\mathchoice{\dbigcupdot}{\tbigcupdot}{\tbigcupdot}{\tbigcupdot}}
% =============================================
%\usepackage{fonttable}
\begin{document}
\centering
$ x \cupdot y$\par
$ x \bigcupdot y \quad \scriptstyle x \bigcupdot y
 \quad \scriptscriptstyle x \bigcupdot y$
\[ x \bigcupdot y\]
%\clearpage\fonttable{MnSymbolF8}
%\clearpage\fonttable{MnSymbolC10}
\end{document}

FOLLOW UP:
The OP asked if MnSymbol can be the default, with (for example), \sum being imported from default LaTeX.  As barbara points out in the comment, the default \sum comes from the cmex font set.  Here, I import it as \Xsum (I am not sure if my \DeclareFontShape invocation is appropriate for cm fonts, but I mimicked what had been done for MnSymbol):
\documentclass{article}
\usepackage{mnsymbol}
% =============================================
%Import symbols from font cmex without importing the whole package
% =============================================
\DeclareFontFamily{U} {cmex}{}

\DeclareFontShape{U}{cmex}{m}{n}{
  <-6> cmex5
  <6-7> cmex6
  <7-8> cmex7
  <8-9> cmex8
  <9-10> cmex9
  <10-12> cmex10
  <12-> cmex12}{}

\DeclareSymbolFont{Xcmex} {U} {cmex}{m}{n}

\DeclareMathSymbol{\Xdsum}{\mathop}{Xcmex}{88}
\DeclareMathSymbol{\Xtsum}{\mathop}{Xcmex}{80}
\DeclareMathOperator*{\Xsum}{\mathchoice{\Xdsum}{\Xtsum}{\Xtsum}{\Xtsum}}
% =============================================
\usepackage{fonttable}
\begin{document}
\centering
sum under MnSymbol:\par
$\sum_{i=1}^2 x_i $
\[\sum_{i=1}^2 x_i \]
Defined Xsum from cmex:\par
$\Xsum_{i=1}^2 x_i $
\[\Xsum_{i=1}^2 x_i \]
\tiny\fonttable{cmex8}
\end{document}

Comment: Hi, the disjunct union symbol is not quite the deal, its the bracket rendering, still its a very kind answer; I'll just try this with the sum operator out of the ams math package.
Comment: @Friedrich I wasn't sure what you had in mind when you mentioned "brackets" (the `\{\}` brace glyphs actually looked very similar to computer modern defaults), so I did not try to do anything with that.  But the framework is here for importing glyphs from `MnSymbol`.
Comment: Could you help me with importing from amsmath anyways or does this method not work with this?
Comment: @Friedrich  In general, each font has a similar, though unique, method.  But in this case, I believe the `\sum` operator you make mention of does not actually originate from the `amsmath` font set, as the loading (or not) of `amsmath` does not change the look of the `\sum`.  Thus, I'm guessing you are actually seeking the `\sum` glyphs from the LaTeX-default Computer-Modern font set (which are discarded with the loading of `MnSymbol`).  Is this the case?
Comment: @Friedrich -- `\sum` is "basic tex".  the definition for these symbols (in the font `cmex`) is found in the file `fontmath.ltx`.
Comment: @Friedrich Please see `FOLLOW UP`.


Acsessing Radio Signals in the middle of Nowhere (North Wales)

Question: Hi I'm about to go to Wales, as a football fan I really would like to be able to listen the matches (especially when you are in the middle of nowhere). Is there a radio I can get (rather not do), or is there a hack or thing to do to get a much better Radio signal.
Comment: I hate to disappoint you but North Wales is not the middle of nowhere.  I have never had any difficulty getting radio reception of any kind at any location.  Also, why is this tagged "eyesight"?
Answer: The biggest thing that will extend the range of a radio is a better antenna.
Note I said "better", which is not necessarily "bigger", though in almost all cases, a better antenna will be bigger than the ferrite core coils used in transistor radios in the 1970s.  Commonly a dipole fairly well matched to the broadcast wavelength and oriented for strongest reception is the best "easy" antenna -- but connecting it to the signal input of your receiver may be problematic.
If you're talking about your car radio, there isn't a practical way to enhance the aerial provided by the car maker (at least that will work while you're actually driving).  If you're talking about a home stereo receiver, on the other hand, there's likely an antenna with it that can be oriented for optimum reception -- and you can, if needed, improvise an antenna and connect it to the antenna terminal on the back of the unit.  In the US, you can even use an old "fishbone" television antenna for FM radio, as they're in the same frequency band (I don't know what bands UK radio and television use, so can't say if that would work there).
I can't tell you what dimensions your aerial will need, however; that would be fodder for another SE (ham radio, electronics, or similar).
Answer: yes. There is (or was) a product called an antenna booster you could buy to enhance medium-wave reception. It consists of a flat plastic rectangle you set the radio on top of. a wire leads away from the rectangle; you stretch this out the window or through the attic in your house. Inside the plastic rectangle is a coil of wire that couples itself to the antenna coil inside your radio, which allows the signal picked up by the long wire to be fed into the radio without having to attach any wires to it.
Some of these boosters also have a tuning knob on them so the response of the booster can be matched to the station your radio is tuned in to. This allows the booster to reject strong signals elsewhere in the MW band, which might otherwise "leak" into your radio along with the weaker signal you want.
Answer: The entire UK has very good free broadcast TV coverage. I suspect many would cover sports events.
Check-out the following, (among many) website for some background of what's available.
http://www.a516digital.com/p/freeview-channels-wales.html


Spanish National Team (Football) store in Madrid

Question: I will be visiting Madrid this summer (July), and would like to know if there's any store where I can buy official Spanish National football team products? Is there an Adidas store that sells them?
Comment: If you want an _official_ store, it would probably help to know _which team_ you're interested in.
Comment: Or do you mean the national team?
Comment: It is indeed about the National team. Question edited so it's more clear. :)
Answer: If you're looking for Real Madrid, the first hit on Google points me to this store location.
Answer: A quick Google search turned up the official online store. The address given is C/ Ramón y Cajal, district Las Rozas. Google Maps shows a putative location for the shop, but Street View shows that there's nothing there. However, just to the north is the Museo de la Selección Española de Fútbol which probably has a gift shop.


What economic policy changes are needed to make Russia a 7- trillion $ economy by 2035?

Question: What specific economic policy changes would you undertake, and how fast would Russia grow under your plan (GDP growth)?
Comment: I'm voting to close this question as off-topic because it belongs on Economics.
Comment: Growing from USD1.5T to USD7.0T in 17 years requires 9.5% annual growth. That's a **lot**.
Comment: Trotsky ousts Stalin in 1927 instead of the other way round. Anything after that is probably too late.
Comment: To those voting to close.  I doubt the economics site would accept questions that are speculative.  Being a fit on another site DOES NOT make it off topic for world building.
Answer: I would start by pointing out that prior to invading Crimea, Russia's Gross Domestic Product was much higher than it is today.  Its best year was 2013 with $2.23 trillion (United States dollars).  It seems quite feasible that making a change that ended the responding sanctions would fix a lot of problems.  In particular, just restoring the 2013 value would reduce the necessary growth to about 6.6% (from about 10.5% needed from the 2016 value).
Realize that the US will have inflation during that time.  So while nominal GDP growth would be about 6.6%, real GDP growth might be only 4% (assuming inflation of about 2.5%).  Real GDP growth of 4% happens in some years for the US.  A sustained period of seventeen years is not out of the realm of possibility for a country that is behind the first world in production.  Note that China's real GDP growth hasn't dropped below 4% since 1990.
Oil could help in the short term, but what Russia really needs is increased industrialization.  They need to produce more with less labor in general.
You could also increase their GDP by adding population.  Assuming the GDP per capita stayed the same, a 1% increase in population would cause a 1% increase in GDP.  A 4% increase in population would give the 4% increase required.  Or mix and match.  A 2% increase in population would allow a 2% increase in per capita GDP to create a 4% increase in GDP.
The growth formula is
$$(1 + r)^t = \frac{\text{GDP}_\text{desired}}{\text{GDP}_\text{current}}$$
or
$$r = e^\frac{\ln\frac{\text{GDP}_\text{desired}}{\text{GDP}_\text{current}}}{t} - 1$$
You can substitute 10 for $e$ and common log for the natural log if that's easier.  Remember to switch both at once if you do that.  The base of the log needs to match the base of the power.
$r$ is the growth rate needed, represented as a decimal
$t$ is the number of time periods (17 years for annual growth rate from 2018 to 2035 in this example)
Hopefully desired (\$7 billion in this example) and current are clear.  I used \$2.23 trillion as current here under the assumption that sanctions would end.  I used $1.2832 trillion (2016 GDP) to calculate the growth rate without that.

Example scenario:  Donald Trump and Vladimir Putin negotiate a deal.  Putin's Russia will take over Syria, Kurdistan (minus the Turkish parts), and Iran.  Russia will crack down on sponsorship of terrorist activity.  Putin will get two warm water ocean ports (Syria and Iran).  In return, Russia will withdraw from Crimea and support the West in subduing the rebels in eastern Ukraine.  Europe and the US will drop the sanctions and provide some backchannel economic assistance.  Perhaps some European manufacturers will be encouraged to open factories in Russia.
I am having some difficulty envisioning a scenario that does not start with the end of sanctions that leads to sufficient growth.  It's not impossible, but it's not trivial either.  It would require a heavy investment in industrialization and possibly some improvements in general governance (less corruption and better regulation).
Comment: Very fine! Glad to see you combined political & economic factors. A major crack-down on corruption could channel wealth into more profitable sectors (if their luck holds). Not investing in defence, which generally isn't productive. Investment in health as well as industry. Economic questions usually don't get good answers. Yours is the exception. Plus one.
Comment: *Russia will withdraw from Crimea* Not a snowballs chance in Hell.  Would burn the Russian soul to do it.  A political non-starter for Russians, I think.
Answer: Oil is the thing that first comes to mind, as Russia was badly hit by the  drop in oil price.
Thus, a sustained oil price boom would boost the economy.
Comment: Quintupling the GDP would require a **lot** of oil, so no, that wouldn't work.
Comment: @RonJohn Wouldn't work? Sounds comparable to the OPEC oil crisis of the 1970s when oil prices went through the roof. Would it happen again? Probably, not. History only repeats as farce.
Comment: @a4android If Russia's complete GDP was in oil+gas exports, then the price of oil would have to go up to $310/barrel.
Comment: @RonJohn Sure thing. To grow any economy takes more than price rises in one or two commodities. The whole economy would need to be boosted.
Comment: @a4android but Russia is a kleptocracy with an alcoholic population in an anti-reproductive death spiral.
Comment: @RonJohn I had noticed. It's one of the challenges of this question: how to grow a basket case economy five-fold.


Time-bandwidth product and uncertainty on harmonics

Question: For a signal that is not corrupted with noise, how is the time-bandwidth product affecting the uncertainty or error introduced when extracting the fundamental frequency ? I mean, instead of choosing the fundamental frequency of the signal at $f_0$, you choose a harmonic $f_k$ at $k\cdot f_0$ and divide by $k$ to get $f_0$. How is the uncertainty related to $k$ for a given frequency resolution ?
Comment: i don't really get the question.  the time-bandwidth product has more to say about how the uncertainty of the frequency measurement (doesn't matter what the frequency actually is, just the uncertainty of it) is related to how long, in time, the signal is.  for $T$ seconds (or whatever time units) of data, you get the same uncertainty (in Hz if $T$ is in seconds) of the frequency estimate.  doesn't matter if it's $f_0$ or $k \cdot f_0$.  same width of uncertainty band of frequencies, same length of time.
Comment: BT product? What the heck is that?
Comment: **BT** product is the **time-bandwidth** product or bandwidth-time product. The former appellation is more common in literature.
Comment: Oh, you mean $BT$ product - now we know it's math.
Comment: @robertbristow-johnson : it is indeed true that the uncertainty is that of the frequency measurement. R. B. Randall in his [book](http://www.amazon.com/Frequency-Analysis-R-B-Randall/dp/8787355078) mentions the standard error being inversely proportional to the time-bandwidth product. Doesn't this have an effect if you had to take relative bandwidths of the different harmonics $k\cdot f_0$ ?
Answer: If you a-priori assume that $k \cdot f$ is a stationary harmonic of periodic waveform of frequency $f$, that implies that you don't have any separable time locality of that harmonic.  But any tighter bandwidth of a frequency estimation might come from the a-priori assumptions regarding the stationarity of the harmonics, not from the data.
Comment: can you please elaborate on the last sentence of your answer ?


What does (R) and (TM) mean in Intel brand name?

Question: I know this question is stupid but could anyone explain it.
What does (R) and (TM) mean in Intel brand name?
For example:

Intel(R) Core(TM) i7-2670QM

Thank you.
Comment: Not sure if off topic...
Comment: Feel free to delete if you want!
Answer: What does (R) and (TM) mean in Intel brand name?
The same as when it appears in any other brand name or publication.
(R) or ® stands for Registered Trademark:

The registered trademark symbol (®) is a symbol that provides notice that the preceding word or symbol is a trademark or service mark that has been registered with a national trademark office. A trademark is a symbol, word, or words legally registered or established by use as representing a company or product

(TM) or ™ stands for Trademark:

A trademark, trade mark, or trade-mark is a recognizable sign, design, or expression which identifies products or services of a particular source from those of others, although trademarks used to identify services are usually called service marks. The trademark owner can be an individual, business organization, or any legal entity. A trademark may be located on a package, a label, a voucher, or on the product itself. For the sake of corporate identity, trademarks are being displayed on company buildings.
Comment: Well, thank you very much for the detailed explanation! I've got it now. Every symbol has its own meaning.
Answer: (TM) or ™ is for trademarks that are not necessarily registered with a trademark office, the US Patent and Trademark Office in the USA. It means the company believes they have a right to that trademark, even though it's not officially registered.
(R) or ® is for trademarks that are registered.
Answer: There are two different symbols are used to represent the trademark (TM) and (R). Where TM represents a trademark registration is under process whereas (R) means the trademark is a registered one.
Here is a trick to type both the symbols on the keyboard, know how: https://www.quickcompany.in/articles/how-to-type-the-registered-trademark-symbol
Comment: Welcome to Super User. OP didn't ask how to type the symbols...


Current divided into components like vectors

Question: Current is a scalar quantity. In Watt-less current, we divide current into components like vectors. Moreover, when AC current passes through inductors or capacitors, we put a vector sign over current. Can anyone please elaborate?
Comment: @MsTais https://physics.stackexchange.com/questions/90995/why-is-current-a-scalar-quantity/91000
Comment: Well, not sure why you are sure that current is a scalar quantity. I may have forgotten undergraduate physics course, but as far as I know, one of the definitions of the current is $\vec{I} = \rho \vec{v}$, where $\rho$ is the charge density and $\vec{v}$ is the velocity of the charge drift. Check your phenomenology.
Comment: Oh, ok, my bad... What I was referring to is current density. Thanks @CooperCape
Answer: In spatial terms current is a scalar. It is the dot product of current density and orientated area.
In ac theory, current may be treated as a vector, because its magnitude and phase can be treated as a vector which rotates continuously in an abstract 'space', not in the real space that we inhabit. It is a mathematical device.


What future can bitcoin have if more and more countries will ban it?

Question: As of today, Russia added itself to a list of countries that ban bitcoin operations.
So is there a future for bitcoin (and other cryptos) if more countries are going to ban them?
Answer: Let's imagine a worst case scenario where bitcoin becomes illegal in all countries. If you put a bitcoin address on your site, you'll get shutdown. If you run a bar and you have the bitcoin logo saying that you accept bitcoin, you'll get fined. Online bitcoin exchanges will be made illegal everywhere.
Even if all this happens, bitcoin as a technology cannot be uninvented. All of this banning will just slow down the adoption. You'll eventually see it uprise again and being used in closed communities worldwide.
People will find other ways of converting fiat currency into bitcoin using decentralized exchanges that go through anonymized tor networks. Local bars and shops will adopt systems where you'll be able to pay your coffee, wirelessly, anonymously, through a hardware bitcoin wallet, without even having to scan a QR code. Paying with bitcoin will become untraceable, ubiquitous and unstoppable.
It's simply a better technology than the current monetary system, and in my opinion history has shown that better technology cannot be stopped no matter the regulations or the policies against its adoption.
Comment: Also I understand enthusiasm and know that technology can not be uninvented, this sounds dubious: a tradeoff of getting a coffee wirelessly and anonymously and be fined for this, sounds not like a good situation to me. Also would you like (as a coffee shop owner) to accept a payment via bitcoin if you know that your business can be closed for this? You can loose your business, but I can hardly see what can you get :anonymity of your customer - you do not care about it, fast transactions (even if we forget about 10 mins) you can easily install terminal with a credit card and be able to use it.
Comment: @SalvadorDali, credit cards have fees for either the merchant or the customer. If accepting Bitcoin will be cheaper, then it will be used. I get your point about being too risky in this scenario, though.
Comment: @ArturoTorresSánchez It is not only about the fees. When you know that your business could be shut down because you accept illegal currency, I highly doubt that a business owner will care about some fees.
Comment: @SalvadorDali, of course, that's why I still accept your point. But I still think it's worth mentioning it.
Comment: @ArturoTorresSánchez got it, thank you. I am aware of the pluses of bitcoin. In this question I was curious whether bitcoin has a future if many strong countries will ban it.
Comment: are you sure? I talked to some bar owners, most of them don't want to lose their liquor license, "Local bars and shops will adopt systems where you'll be able to pay your coffee, wirelessly, anonymously, through a hardware bitcoin wallet,", I can't blame them


Why won't makerbot accept an STL file from Blender?

Question: Our library system just put a 3D printer in one of the branches. I have used SketchUp on the library computers for a number of years just to do artsy things. Suddenly, I have the opportunity to actually print something. (I'm really not sure why the libraries have SketchUp installed. But, I have enjoyed using it.)
There is a plug-in available for SketchUp so that it can export STL files. But, the security on the library computers will not allow me to put a file into the SketchUp plug-ins folder. And, the tech guy at the library doesn't think that the IT guys at the library will update all the copies of SketchUp at all the branches just so someone could do 3D printing.
After doing some searching on this website, I found out that I could export a COLLADA / dae file from SketchUp. I would then import that dae file into Blender (The portable version on my flash drive). I could then export it as an STL file.
The process appeared to work. I could see my test object in Blender.
I gave the STL file to the branch manager who tried to open it in the Makerbot software so that it could be sent to the printer. But, it gave him a message about the file not being recognized.
I am not familiar with all the details in the importing and exporting processes that are going on. Is there someone out there that can give me some help?
One problem is that, I am using the library computers. I cannot alter them. I can use what portable versions of software are out there, like Blender.
Comment: Have you tried installing SketchUp on your flashdrive? There is a free version available
Comment: If you are able to, can you post a download link for the stl file?
Comment: If they are going to offer 3d printing capability, it seems like there would be a convincing argument for having *at least one* of their public computers configured to export to it.  Perhaps the one physically closest to the printer or the office of whoever accepts files?
Answer: Here is what I suggest you try. If you have a file that you can view/edit in blender I would export it as both STL and OBJ formats. Then take those files and upload them to Netfabb (https://netfabb.azurewebsites.net/) and get a "repaired" file. Have the library try again with the repaired STL and OBJ files. If this doesn't work try to get the exact error message/dialog that the makerbot software is giving them as well as the version of the software that they are using.
Comment: It's strange, because an STL is pretty much just a list of triangle vertices with minimal metadata or encoding, and Makerware/Desktop is usually pretty tolerant of typical mesh issues like flipped normals. (It will load them, anyway.) Is blender outputting a binary or ascii STL? Maybe ascii would work if that's not already what it's using?
Comment: We tried your suggstion.:MakerBot error message reads "This file could not be loaded. It may be an unsupported file format."

Netfabb error message reads
""Failed could not load mesh. (invalid .STL file)"
Comment: Okay that indicates that it is almost certainly an issue related to the translation of the file. Did you try with an OBJ file as well? I made a quick box in SketchUp, imported into Blender, Exported the STL and then when I imported it into Netfabb, I got the same error. I tried the same process and when I exported an OBJ it was accepted by Netfabb. Try this and let me know what you find.
Comment: Sounds like Blender's STL output has issues?
Comment: @RyanCarlyle I think it may have something to do with the Sketchup -> DAE - > Blender - > STL workflow. I have great success exporting STL files from modified OBJ/STL as well as native blender formats. It just seems like this is one of those weird combination of things that doesn't seem to work right.
Comment: @RyanCarlyle You are right. I went ahead and went through the above process and when I exported my STL from Blender I selected Ascii and it succeeded in Netfabb. I can't test it in Makerware but I can only assume it would behave similarly. It still doesn't quite make sense that a binary STL works when it is created from a Blender file but not from a DAE. A real head scratcher... At least we have a solution for those that have a slicer that can't handle OBJ files.
Comment: OK - So, I had to leave and come back. Thanks for all the comments. No. I did not try an OBJ file. But, as soon as I was driving off I realized that there was some message about the file being too small when we tried to use the MS netfabb website. So, a little light went on in my head. When I returned, I opened the Blender file and scaled it up in two new files. I was able to fix them with netfabb. So, I will now give the files to the tech guy in the library. It is my unfamiliarity with Blender that caused this. I have only dabbled with it, unlike SketchUp. I will let you know what happens.
Comment: Thanks to all. The tech guy in the library was able to open the STL file with the scaled-up Blender objects with makerbot. It was still tiny when it was opened. But, he was able to scale up the object more and set the exact dimensions in makerbot. So, even though this is a long process, it seems to work. We didn't print the object. It was just a test file to get the process working.
Answer: Makerbot will accept obj files also.
Is there an error while importing the obj file?
Also you can see errors of your imported file in your makerbot
It will be marked in black.

Please make sure your object is a watertight mesh. As I have seen its easy to make a surface model in sketchup. A 3D Printer cannot print something in surface.
You can also try importing to netfabb to check if the part has errors in it.
If you want a better modeling software, I suggest you to check out OnShape.
Its a cloud based cad software. Its free as well. (10 private files, beyond that everything is public. 100$ per month i think)
www.onshape.com


why auto correlation exists

Question: I am wondering what is auto correlation? From the definition of Markov Chain, the  current state should only depend on previous state, why there exist auto correlation?
Comment: Today is related to yesterday and yesterday is related to the day before ... If I only consider a value at time t and the value two days prior, they'll (typically) be related as well.
Answer: Auto-correlation arises in the context of a stochastic time-series $\{ X_t | t \in \mathbb{Z} \}$ where we have one or more variables that vary over time.  Within this context, auto-correlation is just the correlation of a variable at two points in time:
$$\mathbb{Corr}(X_t, X_{t+k}).$$
A Markov chain is defined by the property that the current state is conditionally independent of all states before the previous state, when you condition on the previous state.  This implies that the conditional auto-correlation is zero when we condition on any intervening state:
$$\mathbb{Corr}(X_t, X_{t+k} | X_{v}) = 0 \quad \quad \quad \text{for all } 0< v < k.$$
This does not imply that the unconditional auto-correlation between separated times will be zero.  Since the Markov chain depends on the previous state, and the previous state depends on the one before, and so on, it will generally be the case that states will be auto-correlated over time, beyond just a lag of one.
Comment: thanks! but i am a little confused about the meaning of conditional auto-correlation and unconditional auto-correlation?
Comment: In that case I would suggest going back and learning a little more about probability theory.  In particular, you will need to learn about the difference between marginal and conditional probability distributions, and then marginal and conditional moments.  The difference between conditional and unconditional auto-correlation is just a matter of whether or not you condition on   some random variable in your analysis.

why auto correlation exists


How can I get my trackpad settings to work on the login screen?

Question: I enabled the System Preferences > Trackpad > Tap to Click which causes it to work while I am logged in. However, in the login screen, it does not work. How can I get this setting enabled in the login screen as well?
Comment: Do none of the answers work for you?
Answer: Open Terminal and enter the following commands

defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder

In Finder

open Macintosh HD/Library/Preferences
Ctl+click/right-click a file called .GlobalPreferences.plist and click 'Get Info'
Change the permissions to allow you to alter it but make a note/screenshot of what they are first. (be careful here!)
open the file by double-clicking

Property List Editor will run and open the .plist file

Click 'Root' at the top of the window
Click the 'Add Child' button
Add an entry called com.apple.mouse.tapBehaviour
Make it a Number type
Set the value to 1
Save the file

Back in Finder, reset the permissions to what they were
In Terminal enter the following commands

defaults write com.apple.finder AppleShowAllFiles FALSE
killall Finder

Reboot and the next time you login you should be able to use Tap to click
If you run into issues with Terminal commands or with the plist file make sure your capitalization is correct, case matters!
Answer: The latest method:
sudo defaults write com.apple.driver.AppleBluetoothMultitouch.trackpad Clicking
Comment: Hi Kirby - welcome to Ask Different! On this site, we're looking for high-quality answers that are more than just one-liners. Please elaborate on your answer, explaining why it works and what it does. Thanks, and happy answering!
Answer: I think that this is impossible but I find below post (but didn't test myself)
according to fds post:
defaults write /Library/Preferences/.GlobalPreferences com.apple.mouse.tapBehavior -int 1

Answer: I don't know if this is still the case, but the login window's session used to be run as root. So if you enabled the root account, logged in as root, and set whatever trackpad or mouse settings you liked in System Preferences, they would be applied to the login window.
Comment: I dont think this is true, at least as of 10.6 or later. Just tested it to be sure :-)


Scara robot design

Question: I found this drawing on google photos:

I don't understand why he used this part.

Is it for reduction?
What is its equation?
Answer: One of the problems with a belt driven SCARA system like this is that as the belts age, they stretch, so every belt should have a tensioner.
If you look carefully, it is clear that plate 106 rotates around shaft 114, and you can see the spring which provides the tension below it. Cogs 102 and 104 are free running. When the belt is new, plate 106 will be pushed close to the position shown. As the belt ages, the force of the spring will rotate plate 106 anti-clockwise, maintaining the tension of the belt.
This design cleverly tensions both straight sections of belt at the same time, by the same amount, and with the same pressure. This should make the system less susceptible to problems with unidirectional repeatability (moving from -90 to 0 resulting in a different position than moving from 90 to 0 for instance).
Comment: The function of the bi-directional tensioner is also explained quite clearly in the [original patent](https://www.google.com/patents/US4693666) document. :)
Answer: The circled assembly is a bi-directional tensioner which maintains the tension in the drive belt at a pre-determined level as the belt ages and stretches. The detailed description of the function of the assembly is explained in the original patent document (US Patent 4,693,666), available on Google patents:

The bidirectional tensioning for the belt 60 ... as shown in FIG 5, is achieved by the bidirectional belt tensioning and idler device 100 positioned within the belt loop and intermediate the toothed gears 56 and 62.
The device 100 includes rotatable toothed rollers, or pulleys, 102 and 104 for internal engagement with opposite lengths L1 and L2 of the belt 60 which are moving in opposite directions. The rollers 102 and 104 are connected by a yoke 106 which connects the supporting axes of the rollers. The device 100 is rotated about a torquing arrangement 110 which extends through a mounting plate 112. The torquing arrangement 110 includes an adjustable tensioning element 114 for rotating the 100 relative to the belt 60 to establish the desired tensioning of the belt 60.
Once the proper tensioning is established, the device 100 is secured by the fasteners. The desired belt tension corresponds to a predetermined torque associated with the tensioning element 114 and thus the belt 60 can be pretensioned via the tensioning device 114 without requiring visual access to the interior of the primary arm assembly P.

I've included the original diagram below for ease of reference:

When modelling the SCARA robot, this assembly should not need to be modelled with a separate equation. The function of the unit is simply to ensure that the drive assembly performs as expected, so you do not need to modify the equations for the drive assembly to account for the drive belt ageing and stretching over time.
Comment: Nice find, I should have guessed from the style that it was a diagram from a patent application. It's obvious from the pdf name (that I clipped) now that you mention it.

Scara robot design


Uses of Jacobian of a map on $\mathbb{R}^n$.

Question: For a map $f:\mathbb{R}^n\to\mathbb{R}^n$, Jacobian matrix of $f$ is defined as $$\begin{bmatrix}
\frac{\partial f_1}{x_1}& \frac{\partial f_1}{\partial x_2}& \ldots \frac{\partial f_1}{\partial x_n}\\
\ldots  & \ldots & \ldots  \\
\frac{\partial f_n}{x_1}& \frac{\partial f_n}{\partial x_2}& \ldots \frac{\partial f_n}{\partial x_n}
\end{bmatrix}.$$
And determinant of this matrix is called Jacobian of $f$. I know that in case of a continuous function on $\mathbb{R}^n$ (and for certain classes of functions on $\mathbb{C}^n$) also), non vanishing of Jacobian at a point implies local injectivity at that particular point. Beside this, can anyone help me why and how this Jacobian is useful? Any historical reasons, why this was introduced. I searched online about it but could not gather much information. If anyone can give me some information about this.
Comment: It's used in change of variables for multiple integration. Very useful and important.
Answer: One immediate application of great consequence that comes to mind is the Jacobian of the endomorphism of the tangent space of an embedded surface in 3-space, known as the shape operator (or the Weingarten map). This Jacobian (i.e., the determinant) happens to be the extremely important invariant called the Gaussian curvature of the surface.
More generally, the Jacobian appears in change of variable formulas for multiple integrals. One can't do multivariate calculus without it.
Answer: To further my comment, the Jacobian can be thought of intuitively as follows.
For a sufficiently nice function $T:\mathbb{R}^n\to\mathbb{R}^n$, we can locally approximate $T$ around a point $x$ with the linear function $$T(x)+\mathbf{DT}(\Delta x)$$ where $\Delta x$ is the change in the vector $x$ and $\mathbf{DT}$ is the derivative matrix of $T$.
From linear algebra, a linear transformation $L$ with determinant $\det L$ distorts the volumes of objects by a factor of $|\det L|$. Thus, around the point $x$, the function $T$ will distort volumes by a factor of $|\det \mathbf{DT}|$. But this, by definition, is the Jacobian (perhaps without the absolute value, depending on who you ask). This is also why the Jacobian appears in change of variables for multiple integration - it plays the same role that the $x'(u)$ plays in $u$-substitution.


Arrogancy vs. Humility

Question: Is there a word or phrase to describe a state of mind within an arrogant person who has been overwhelmed in a debate by another person who is humble in his/her demeanor, but armed with the truth to the convincing of the majority present. I am looking for something more descriptive than simply embarrassment.
Comment: (Arrogance, not arrogancy.)
Comment: @Drew- The word 'arrogancy' can be found in the 1947 edition of Webster's New International English Dictionary. I looked it up this morning to make sure. Why it's not included in the English SE's data base isn't known. Thanks for your input.
Comment: @DuaneT.Bentz What do you mean about "inclusion in the English SE's data base"? Please be aware that the *Oxford English Dictionary* reports that the elder of the two terms, [*arrogance* dating from 1340](https://www.oed.com/view/Entry/11054), enjoys a commanding ***thousandfold*** frequency of use advantage over the younger term, [*arrogancy* dating from 1477](https://www.oed.com/view/Entry/11055). The latter is so sparsely attested following the mid-1600s as to be comparatively nonexistent, a situation that will surely lead many to think its use a mere typo. Only *arrogantness* is rarer.
Answer: Who can really say what that person feels or even if they'd experience embarrassment if they are so arrogant?  Unless they had a sudden epiphany that they were "bested" by someone, regardless of the victor's demeanor, they could be chagrined, dumbfounded, 'put in their place', impressed, surprised and even your word...embarrassed.
Comment: Is there a good source depicting the above scenario and emphasizing the reaction shown forth by those demonstrating arrogance to a single person who defends the truth?
Answer: Sounds to me like they've been "brought down a peg or two" (slang).

to do something to show someone that they are not as good as they thought they were

OED 'peg' (n.1.II.3) has

a. The interval between two successive positions, such as could be marked by pegs; a step, a degree. Esp. in to take (a person) down a peg (or two) and variants: to lower (a person) in his or her own, or the general, estimation; to lower a person's view of his or her own status or ability; to humble, chasten, snub. Also to take (a person) a peg lower . Similarly occas. to come down a peg
Comment: That's a good expression - but does it describe the state of mind of the arrogant person or is that a judgment of the onlookers - that the arrogant person was brought down a peg or two?
Comment: If I was a witness to the event, I might be apt to think the person was taken down a peg or two but if I was the arrogant person, I can't say I would think that about myself.
Comment: That's true, because it's pejorative in that it implies the person was arrogant in the first place. Arrogant people never think that they're arrogant. ;)
Comment: Right!  Well put! :-)
Comment: Interesting question. I think it's 'the judgement of the onlookers that the state of mind of the person in question is now less arrogant than it formerly was'.
Answer: In waiting for a further response to my question and reading none, I have decided to answer it myself having compiled information these past couple of days. First, I will pose an additional question to promote the idea that an observer can discern another's thinking in certain circumstances, namely: What is an outward appearance or reaction to an inward feeling? All of us are capable of many and can be discerned by those who can recognize them from experience. I have three examples hereafter:
The Trial of Socrates of 399 B.C. The main accuser was a man named Meletus and according to Plato's account of the trial, Socrates making defense for himself managed to make Meletus appear "dim-witted" or stupid and thusly his accuser would have demonstrated a surprised countenance and probably embarrassment before the court officials and 500 jurors.
Jesus of Nazareth facing his accusers who outwardly demonstrated their arrogance and hatred toward him yet as the Biblical account says they "marveled" on his intelligence and self-control in face of their efforts to trip him up. At his trial, Pilate also marveled as he witnessed Jesus under fire. To marvel is: to be struck with surprise, astonishment or wonder. Wonder is "the emotion excited by novelty, or the presentation of something new, strange extraordinary, or not well understood..." from Webster's New International English Dictionary, 1947.
The account of a prophet named Abinadi- "And they began to question him, that they might cross him, that thereby they might have wherewith to accuse him; but he answered them boldly, and withstood all their questions, yea, to their astonishment; for he did withstand them in all their questions, and did confound them in all their words." from Mosiah 12:19, The Book of Mormon. The key words here are astonishment and confound which are defined as "To stun; to render senseless; to stupefy the mind of, bewilder and lastly to overthrow, respectively. I would welcome other accounts from the academic community.
Answer: If a supposedly arrogant person was thoroughly bested in a debate, and acknowledged that loss, I believe the following terms would accurately describe his feelings:
"Shamed", "Mortified", "Humiliated", "Embarrassed",  "Defeated"
Answer: I think the adjective "humbled" could fit well here but really this all depends subtly on what you're trying to convey about the internal mindset of the loser.  IF they still feel arrogant and just bested and have a feeling of anger or resentment or feel they've only been lowered in the eyes of the audience, then "embarrassed", "chagrined" and other options mentioned above would fit better.  If as other's mention, they acknowledge the loss and reevaluate the opponent or themselves, then it could be they feel "humbled", "shamed", "chastened" etc.

Arrogancy vs. Humility


Every time I try to play on a multiplayer SMP server, I get nothing but an empty blue world. How do I fix this?

Question: Every time I go to play on a multiplayer SMP server, I join, it pops me in, and then I fall into nothing and stand on nothing. It's all blue; all I can see is the sun and sky. How do I fix this?
Comment: Is it permanently like that? 1.3 has a horrible bug that loads every chunk around you starting from the outermost and finally ending with the chunk you're occupying. It should eventually load the world if you wait long enough.
Comment: It could be your internet. Our server takes roughly 20 seconds to show terrain for new players because they have to download all of the chunks. Try leaving your computer idle for a few minutes to see if anything appears.
Comment: I agree with @Kevin - based on the speed of your computer, it could take a couple minutes to fully render what you're standing on.
Answer: This is likely just a slow server/internet connection. Have you tried waiting a few minutes? I find on my connection that some largely built and developed servers with many players such as the Reddit Server, loading the chunks at spawn can take 2 or 3 minutes.
Answer: I have had this problem before. No matter how long you wait nothing will ever load. You need to close Minecraft and wait a few hours. After that you need to re-open Minecraft and attempt to connect to the server again.
Comment: Can you explain why this works / how you know it works? Without including background justification it sounds like it could just be cargo-cult superstition.


Yearly Time series analysis

Question: I am using time series modelling to remove the time series error of a linear regression model. Based on the ACF and PACF plot I used AR(1), MA(1) and ARMA(1,0,1) for the different models.But the Ljung box statistics shows mostly significant values. How do i interpret if the model is okay? Does the Ljung box statistics have to have all non significant values for the model to be correct.  Or is it like if the Ljung box statistics values are not significant upto lag 10 the model can be considered. My aim is not to forecast but just to remove the time series error and obtain correct coefficients. Thanks in advance.
Answer: I think you need to first check whether the series is stationary before model fitting and looking at the Ljung box test. The stationarity check will help to tell you whether you need to do de-trending or differencing to your data. After that you can do the ACF, PACF and ARMA, ARIMA fit and make sure the Ljung box is not significant at least for all lower orders
Comment: Thank you for the response. I had checked for the stationarity of the series and would like to know that if there is no autocorelation upto say 10 lags, can we still consider the model(as shown by Ljung box statistic). The total number of data points in the series being 100. Please help.
Comment: If that's the case yes you can check the model using the ljung-box test. If your ljung-box statistics are mostly significant as you stated in the original question, then it implies that the residuals from your model still are highly correlated.  Therefore the inferences you want to make would still be impacted. In other words the model is not good enough --- you may be able to further improve the model.

Yearly Time series analysis