Selecting specific point within specific polygon using ArcMap

Question: I am using ArcMap.
I have a shapefile points layer, with each point representing either marginal, suboptimal, or optimal conditions. I want to find only the marginal points within a specific polygon from my catchments polygon layer. So far I have been able to select all marginal points, or the wanted polygon, but not the marginal points WITHIN the specified polygon.
Is this possible?
Answer: 1) Select your polygon of interest - you can do this manually or with one of the selection tools.
2) Select your 'marginal' points using the Select By Attributes tool with the Method drop-down set to 'Add to current selection'.
You will now have a selected polygon in one layer and selected points in another layer.
3) Use the Select By Location tool to select all 'marginal' points within your selected polygon by checking the 'Use selected features' checkbox.
This will produce a selection of only those point features specified as being 'marginal' within your polygon of interest.
Answer:
Select by attributes for Marginal
select polygons of interest
select by location

make sure the selection method is select from currently selected
features
choose your points in the target layer and your polygon
layer in the source layer
make sure the Use selected features box is checked
selection method is target layer is completely within the source layer


MariaDB Power Outage Issue

Question: We have a desktop application on Windows OS that installs with MariaDB server 10.4.10. Sometimes the client loses power and after restarting of PC MariaDB database becomes corrupted and Windows Server is not starting. The logs show that some tables are randomly broken.
The server configuration is the default, not heavily loaded with one request per 1-5sec.
I'm wondering if there are some configuration changes that can help avoid or at least decrease the probability of this issue?
Comment: Do you define all tables using the InnoDB storage engine? InnoDB has crash protection, other storage engines do not. For example, if some tables use MyISAM or Aria, they are susceptible to corruption when the OS crashes. This can happen even if the load is not heavy.
Comment: @BillKarwin yes, all tables are InnoDB
Answer: Most likely it is because of Windows write caching.  While caching provides speed, it also defers writing to disk. You dont normally want to remove it for everything.
One way to fix it,

create a new partition on your disk
move the database files onto it
disable write caching.

Note that there is the Flush command in MariaDB, that you could try.
Comment: Thanks. What is the case to use Flush command? If PC was rebooted after power was lost and data is broken on the disk no reason to use this command, right?
Comment: If you are frequently changing table structure upgrade to 10.6+ that has crash safety around table modifications.
Comment: I doubt if any option to `FLUSH` is relevant.

MariaDB Power Outage Issue


Is perchloride the same as perchlorate ion?

Question: I read about perchloride in a talk and after trying to search for its chemical formula, the search results imply that perchloride is actually named perchlorate. Is this correct?
Answer: Short answer: Yes, sometimes "perchlorate" can be called "perchloride" in older literature, but because of the classical definition of a "perchloride", it's so confusing and technically wrong that the $\ce{ClO_4^-}$ anion should be called either "perchlorate" or "chlorate(VII)".
In older naming systems, pre-IUPAC, a "per-ide" is quite simply "any substance containing an unusually high proportion of the named element". So, a "perchloride" is any substance with more chlorine than is "normal" for that mixture of elements. This name was typically given to metal halide salts where the metal has multiple possible oxidation states; the highest oxidation state of the metal forms the metal "per-X-ide". for instance, titanium perchloride aka titanium tetrachloride, $\ce{TiCl_4}$ (IUPAC name titanium(IV) chloride), as differentiated from the trichloride and dichloride salts of titanium, and iron perchloride aka ferric chloride (that name's rarely used as iron only has two stable chlorides, and so the traditional "ferric" and "ferrous" descriptors work fine).
However, the perchlorate anion isn't actually a "perchloride" by that definition; it's more a "peroxide", as there's only one chlorine (which is relatively "normal") that has been "superoxidized" by four oxygens (not normal).
This use of "perchloride" as a synonym for "perchlorate" is more the result of a bad simplification of the traditional naming system, where salts of "-ic" acids are "-ides". While the rule follows for the hydrohalic acids (HF, HCl, HBr, HI) and most oxoacids (which, when they end in "-ous", form "-ites", as in hypofluorous acid, chlorous acid and sulfurous acid), the highly oxygenated oxoacids like chloric, perchloric, sulfuric, nitric, phosphoric and boric acids form "-ates", not "-ides", to mirror the low-oxygen "-ous" acids and their "-ite" anions/salts.
When not talking about the perchlorate anion, you sometimes hear about organic molecules that have had all their hydrogens replaced by halogens. Perchlorocarbons and perfluorocarbons are the chlorine and fluorine derivatives of hydrocarbons (for instance, the dry-cleaning chemical perchloroethylene, "Perc", and the perfluoroethylene monomer of polytetrafluoroethylene, aka Teflon).
"Peroxide" has found a home in the IUPAC system as the official name of the $\ce{(O_2)^{2-}}$ anion, composed of two single-bonded oxygens (often as the related "hydroperoxide", which is an OOH functional group bound to a carbon or to hydrogen). However, because each chlorine anion in a "perchloride" is typically bound to whatever the chlorine is oxidizing, the multiple chlorides are not a single anion and so aren't named as such in IUPAC.
Answer: -ide means the lowest oxidation state. For $\ce{Cl}$, if it gains 1 e$^-$, oxidation state is -1 (i.e. $\ce{Cl-}$); in case of $\ce{S}$ (16th group) it's 2 e$^-$ (i.e. $\ce{S^{2-}}$)
per- means higher than usual oxidation state. For $\ce{Cl}$ it's +7 ($\ce{ClO4-}$); for $\ce{S}$ look at compounds with O-O bond (peroxomonosulfate $\ce{SO5^{2-}}$)
So per*ide like your perchloride is an oxymoron.
Compare http://en.wikipedia.org/wiki/Chlorite
Answer:
per- -ide

Refers, as far as I know, to double anions. For example: $\ce{HgCl2, H2O2}$ are named "Mercury dichloride" and "hydrogen peroxide" respectively. I believe that "per- -ide" has been dropped for most cations (e.g. $\ce{HgCl2}$ was previously called "mercury perchloride"). "Peroxide" is the only one I've still see a lot around.
On the other hand,

per- -ate

Refers, as far as I know, to anions derived from 'per- -ic' acids. Perchloric acid is $\ce{HClO4}$ and perchlorate is $\ce{ClO4-}$
This system of naming isn't so common now. We generally refer to 'chlorate' or 'chloride' and indicate the oxidation number.
E.g. $\ce{NaClO4}$ is now often referred to as "sodium chlorate (VII)" instead of "sodium perchlorate".
You might want to look a bit into the wikipedia article.
Comment: "Peroxide" stuck around because IUPAC adopted the name as the official term for the $\ce{O_2^2-}$ anion.
Answer: Perchloride is a word that has been used 100 years ago in the expression Iron perchloride to describe the Iron(III) chloride $FeCl_3$, so as to avoid any risk of confusion with the more usual Iron(II) chloride $FeCl_2$ which is obtained in the reaction of Hydrochloric acid with metallic iron. This prefix shows that there is more $Cl$ atom in $FeCl_3$ than in $FeCl_2$.
The prefix per- is used for translating more. Today it is only used in expressions like perchloric acid or perchlorate ion. It points out that the Chlorine atom is more oxidized in these substances than in any other chlorine compounds.
Today nobody uses the prefix per- before chloride any more when speaking of $FeCl_3$, because it is not the $Cl$ atom that is oxidized, but the $Fe$ atom.


Minecraft chunk generation via version

Question: So in minecraft  if i make a copy of a world (that has not been explored yet) and explore on the copy will the original world have the same chunk generation (same biomes, caves, structures, etc) as the copy (yet original still not explored) or will the original update according to the version?
Comment: What you are referring to is world generation, not chunk loading, and new chunks will be generated accordingly to the game version, if the version is the same then the world will always be the same.
Answer: The chunks that have already been generated will retain their state.
Chunks that have not been generated will generate in on the current version. This applies to any situation, for example just using a world from an older update. The current version is used.
Answer: I'm glad I can help you.
The following is my personal opinion.
First of all, we need to understand that if we copy a world, the seed of the world itself will not change. When minecraft generates the world, there is a set of complex algorithms that will not change. Just because it will not change, when inputting the same seed (equivalent to copying a map that has not been explored), it will not change, The generated world is exactly the same. Minecraft's world does not generate a new block temporarily when the player moves out of the block or visual range, but it is calculated by default at the moment when the seed is set to load the world. However, in order to save memory, it will only load an area where you are, otherwise it will occupy more memory than you think.
Secondly, if you play in the old world with the new version, the things in the old world that have not been removed in the current version still exist, and the material will change with the new version. But if something is removed, the situation will be very complicated.
In addition: remember not to play with the old version of the new version of the world, otherwise the new content will be considered unknown box (or entity) and replaced with air (which also means that it is useless to load in the new version again)!
Comment: this is a non answer
Comment: It's a bit unclear what the final answer is. Could you [edit](https://gaming.stackexchange.com/posts/381827/edit) in a phrase saying directly what the answer is? I could tell you tried to answer it but it's a bit hard to tell the final answer.

Minecraft chunk generation via version


Is it normal the .cache/mozilla/firefox/ to contain files of the type 'application/octet-stream'?

Question: I am running a Linux-PC with Firefox last version.
Is it normal the .cache/mozilla/firefox/ to contain files of the type 'application/octet-stream'?
Answer: It's entirely normal - there is no reason to exclude files based on their type.
I can see such files in my own cache. I'm using Nirsoft's
MZCacheView
in Windows.
Answer: application/octet-stream is nothing more or less than "this is some uncategorised data"
It could be an image, a video or just some gzip compressed webpage data.
Not all web servers properly check and send the correct file type for data and instead leave it up to your browser to download the file, check the data for type information and then display as necessary.
It is not a sign of anything out of the ordinary, nor is there anything actually wrong.


How can I change the date format in a Search Kit result?

Question: I have a Search Kit search that shows the date like this: November 1st, 2012 12:00 AM.  I want to reformat this as 11/01/22.  How can I do this?
Answer:
You must be on CiviCRM 5.47+ to have the "Use Smarty in Search Kit rewrites" feature.
Create a Search Display based on your search - e.g. Add » Table using the Add button in the left pane.
Find your date field and check the Rewrite box.  You'll see a token that represents your date, e.g. [receive_date].
Change the rewrite value to the following.  Substitute your token for [receive_date] below.

{"[receive_date]"|date_format:"%D"}

A full list of date formatting options is available in the Smarty date_format documentation.
(Ignore the older rewrite text in the screenshot, the value above is the improved version!)
Comment: 0

Do you have to enable the smarty option? We have tried the above but all the dates are coming out as todays date in the output

Olly
Comment: @OliverGibson There's nothing you need to set.  I just recreated this on a brand new Civi and took a screenshot, which I added to the answer.  Hopefully this clears things up?  If not, hit me up on chat (@junglebird)


How does a spacecraft know what communication network to use?

Question: Spacecrafts use different networks like TDRSS, DSN, ... to accomplish uplink/downlink. But how does it know which one to use during the mission? At what point does it find TDRSS more suitable than DSN (Brazil)? How does it know which TDRSS satellite to point its antennas toward?
Answer: In the event that a spacecraft has multiple communication systems, it can chose which one to use by a few ways.

Test receiver by each network, and use the best one. This is pretty much what your cell phone will do when connected to both wifi and 4G/5G. Figure out which one is best, and use that one.
Simultaneous communicate via both- Used for really mission critical stuff, primarily for human systems at critical moments.
Time boxed- Use one system at one time, another at another time. Can also apply to location, use one system over one part of the globe and another system elsewhere.
Condition based- If your pointing is great, use the high gain antenna. If it is not quite so great, use the low or medium gain antenna system.
Comment: For number 1, Is this accomplished by the link budget calculation?
Comment: Just look at a carrier signal and figure out which one is best. Or even transmit a small packet on each to see which gives the best results.


How does sequence alignment help with protein folding prediction?

Question: I've been seeing using sequence alignment to help with prediction of protein folding, but am unable to understand why. Google returns other research papers for these search terms, hence I'm hoping the stackoverflow community can help thank you.
Comment: Where did you see using sequence alignment to help with prediction of protein folding? Perhaps I just too far from the topic to understand the question, but I find hard to understand where the question comes from and I wonder if there is a one correct non-opinion-based answer.
Answer: Protein sequences from the same family form a sequence alignment. Some positions in the alignment will be conserved, i.e. the same in all sequences. These are often associated with function, e.g. a catalytic residue at position 50.
However there is a more subtle signal in sequence alignments called covariation. Two positions, say residue 30 and residue 60, may appear to change together across the alignment. We infer that they are close in 3D space in the structure:

Initially statistical techniques (DCA, PSICOV etc.) were used to separate direct from indirect (chained) couplings and extract predicted contacts from sequence alignments. Now deep neural networks have improved performance and even allowed the prediction of residue-residue distances and orientations.
These constraints on the structure allow model building, for example using the CNS software. A good set of constraints effectively guarantees the correct fold. The depth and quality of the sequence alignment is the major factor in the accuracy of the predicted constraints.
This approach to protein structure prediction is the current state of the art. Use of covariation from sequence alignments is the only approach that has reliably given accurate models for larger proteins without templates. See this paper and this paper for the best current methods, and tune into the CASP conference this December to see if anyone can improve on them.
Comment: Verified top answer @pohje please mark as "resolved". The technical theory is called "convolution" regarding direct and indirect couplings - you can't just use raw covariancce because you get artefacts, but simplicity you can think of it as just covariance.


CSV won't import correctly into Arcmap 10.3

Question: I have a spread sheet with coordinates that once I bring in to Arcmap, the attributes disappear. The points are on the map, and when you Identify each point, the data shows up, but when the attribute table is open, the attribute titles are there, but no data below them. I have another table with data that comes in as it should. I was able to Display XY data and reproject, and the attributes showed up, but then there was only one point on the map (there is a total of 15). I've attached a screenshot of the excel table, but let me know what other info is needed.
Comment: The column names might be causing issues. Try simplifying them by removing punctuation and spaces just to see if that's the issue. Also, if commas (,) are your delimiter, make sure your cell values are surrounded by double quotes (") if your cell values contain commas.
Comment: Does the table data display BEFORE you display X, Y locations as points on the map?
Answer: Be sure of the type of your columns (date sometimes crash) and their names (no space, no special characters). It could also be the encoding (make a try with UTF8.) or your csv delimiter.
Answer: Here is a very useful ESRI blog you (and anyone else) who intends to link data held in Excel with ArcMap should read.  It explains the many pitfalls there are with Excel.
I personal avoid using Excel like the plague and get my data into personal geodatabase which is essentially a spatial enabled Access database. Much easier to read and write from and you have ObjectID fields.


Is it generally safe to install VirtualBox remotely?

Question: I need to install VirtualBox on a PC that stands in the field.
I access this PC remotely via TeamViewer/VNC.
Is it reasonable safe to install VirtualBox on this remote PC given that the installation will likely reset my connection?

The PC is several km away from the nearest technician, so having to fix something physically would be an enormous headache.
Answer: If you cannot afford permanently losing network connectivity, you should create an identical local testing environment with the same remote control tools and see what happens during the installation. The results should be interpret with caution: if you lose connectivity, you have a chance to try with an alternative configuration, but a successful test cannot be held as a guarantee to success on production.
With the TeamViewer's Unattended Access -feature you are likely to survive even when the installation causes the remote computer to temporarily disconnect from the Internet. That is, unless the installation prompts for something during the period the computer is disconnected. In other words, this is exactly what you should be testing.
Answer:
If the connection is not reliable with static IP address I suggested DO NOT try to install Virtual Box

If in that PC reside a important application I suggest DO NOT try to install Virtual Box

I suggest you manage the application with a secure SSH session instead of try install Virtual Box. This is due to as per for the screen shot the Operating System (OS) is a version of Windows.


Morphia Add item to embedded

Question: I have the following structures.
Products is embedded in Store; and reviews is embedded in product.
1- Store
  2-Products[]-->
     3-Reviews[]

I am trying to add a new item to review with the following code. It doesn't give me an error but neither does it add it.
Query q1=ds.createQuery(Product.class).filter("Code", code);
if(q1.countAll()==1)
    {
    ops = ds.createUpdateOperations(Product.class).add("Reviews", review);
    ds.update(q1, ops);
    }

Answer: I figured it out. The only was is query for the embedded product, modified it by adding a new review and update that product with ds.CreateUpdateOperations().Set(ops)

Morphia Add item to embedded


Which advanced mathematics book do you recommend for a college starter?

Question: I'm supposed to start my preparation for the college admission math exam so I'm looking for a good explanatory/textbook/problem book which covers most of or all of precalculus topics with a hint of calculus on an advanced level. By that I mean it should not just explain a topic, give a few minor examples and take off. Rather it should go in depth and explain deeper things about that particular thing. Is there such a book?
Comment: Ok in the first i meant shouldnt
Comment: OK, I edited your question to match your comment.
Comment: What exams? Different exams cover different material at different levels of difficulty.
Answer: Gelfand's Algebra, Trigonometry, Functions and Graphs.
Answer: Calculus by Michael Spivak is one of the best textbooks I've ever seen. It provides leisurely explanations, a profusion of examples, a wide range of exercises and plenty of illustrations in an easy-going approach that enlightens difficult concepts and rewards effort.


Where does "I'll go he" come from, and is there more to the phrase?

Question: I understand the meaning of the saying "I'll go he", but does anyone know where it comes from?
The researcher here seems to think that there is a couple of words left off.
Comment: [A Dictionary of Catch Phrases](http://books.google.co.uk/books?id=Nm3jbg0JalMC&pg=PA230&dq=%22i'll+go+he%22&hl=en&sa=X&ei=DVrmUPDWFfOM0wWhlYDYAw&ved=0CDUQ6AEwAA#v=onepage&q=%22i'll%20go%20he%22&f=false) *I'll go he! is a NZ c.p. exclam. of surprise: since c. 1920. From those children's games in which one participant is either blindfolded or otherwise made the 'victim'. Cf: I'll go hopping to hell!*
Answer: According to ABC.net.au,

It turns out that "go he" is an expression that comes from children's games. In many games (hide and seek or piggy-in-the-middle, or chasings) there's one child who is "in" or "it" or "he" (depending on where you grew up) – the one who seeks or chases. When used by adults the expression "I'll go he" is a statement of confidence – "I'll go he" is an offer to do something unwelcome or unlikely – an offer that can be made because the speaker is so confident of what they've said.¹

I do not put a lot of stock in the comment of the researcher who said there were a couple of words left off, shared with him by Australian reference librarians, but then refused to disclose them. Supposing the researcher is honest, there is still too much distance between him and a reliable reference source. His theory of two missing words – whatever they are – is hearsay at best.
It is equally likely that these librarians consulted a slang dictionary, possibly Cassell's Dictionary of Slang by Jonathon Green (Weidenfeld & Nicolson, 2005) –

I'll go he! excl. [1950s+] (N.Z.) an excl. of surprise.
I'll go hopping to hell! excl. (also I'll go hopping! I'll go hopping to hell backwards!) [20C+] an excl. of amazement, approval or admiration.

– or A Dictionary of Catch Phrases: from the Sixteenth Century to the Present Day by Eric Partridge, edited by Paul Beale (Routledge, 1986) –

I'll go he! is a NZ c.p. exclam. of surprise: since c. 1920. From those children's games in which one participant is either blindfolded or otherwise made the 'victim'. Cf:
I'll go hopping to hell!—esp. when prec. by well, an addition that affords a vigorous rhyme. Indicative of astonishment—or of profound admiration—or of both: C20. See well, I'll go to Hanover!

– and that the librarians (or the researcher) jumped to the conclusion that the two exclamations, adjacent on the page, were necessarily related.
Answer: I'll go he is found in Australia from the 1910s.
I'll go hopping [to hell] is found in Australia from the 1920s.
I don't know for sure, but as both are found in the same country around the same time, it's possible the former is a polite euphemism for the other, it probably being unacceptable to publish the latter in earlier times.
I'll go he
I'll go he dates from at least the 1910s in Australia, so possibly earlier with a New Zealand origin. It's used in the form:

"If something happens that I think is unlikely, then I'll go he".

Searching the Trove archive of Australian newspapers (1803 - 1954) gives this from The Mail (Adelaide, SA)  of 21 December 1912 in a letter from a Mr EC Murch:

If each one sells as many as the enterprising secretary, then the coffers of the Society for Prevention of Cruelty to  Animals will get a big lift. To use his words— "I am going down to the Port races on Saturday, and if I don't sell a hundred tickets I'll go he."

From "Gittin'-Up Time: A Bushman's Bleat" in the Sunday Times (Perth, WA) of 22 June 1913:

Said Bill: "I came down here for a
  spell. I want to rest in the mornings.
  I struck a joint last night, and they
  had me up before the sparrows. Look
  here, Sam, I'm a full Jerry to your
  little joke, but if your joint is worse
  than mine, spare me days, I'll go he!
  Lead me to it."

The Northern Miner (Charters Towers, Qld.) of 26 October 1920:

Mr. Thespian: Look here, Mrs. Chatterbox Thespian, I'll "go he," if you can tell me how Mr. Adler can conscientiously be a Prohibitionist.

Here's also a 1928, 1935, 1938, 1939, 1940 (see below), 1941, 1942, 1954, 1954, 1956 and 1956.
In 1940 (also reported here, here, here and here) an MP made a one and half minute speech in the House of Representatives:

Then with the words — 'If
  that is not the shortest speech
  I've. made in' this House, I'll go
  'He' ' — He sat down.

I'll go hopping...
I don't know if I'll go he actually derives I'll go hopping [to hell]! but this phrase and related phrases (to heaven/hades/h----/----) can also be found initially used in a familiar manner Australia from the 1920s:

"If something happens that I think is unlikely, then I'll go hopping [to somewhere]".

Or later exclaimed when surprised by something unlikely:

"Well, I'll go hopping [to somewhere]!"

The Recorder (Port Pirie, SA) 15 August 1925 writes of a football match:

'What do you think of the umpire?', queries No. 1. 'Oh ! he's not bad,' I replied with a show of wisdom. That did it. 'Not bad!' came the response, accompanied by a disgusted snort; 'Not bad! Where's your eyes?' If he isn't favoring the -------- I'll go hopping.' I endeavored a feeble answer. 'You're one eyed,' was the retort I received.

Townsville Daily Bulletin (Qld.) of 16 February 1933:

... and he dumped the end of the sapling with all his force into the middle of the fire. 'Well I'll go hopping to China' yelled the other, 'If you haven't squashed my damper.

Williamstown Chronicle (Vic.), 12 May 1934:

THAT recently a weeklly paper in
  the "big smoke" referred to the
  League as "the parent body." Well,
  I'll go hopping to h-------! That's
  the first time I've ever heard of the
  child being born before the parent!

Western Argus (Kalgoorlie, WA) 24 November 1936 (republished here, here, here, here, here and here)

One habit Bruce had cultivated,
  that of expressing his feelings when
  under the stress of great emotion
  without resorting to the practice of
  using bad language.
"Well, I'll go hopping to heaven
  in hobblechains," he muttered, more
  surprised than he had been at the
  appearance of the "ghost" and its
  sudden and unexplainable vanish
  ing.

Advocate (Burnie, Tas.), 5 October 1938:

He says a sports meeting and outdoor display are tame. So he suggests a photography competition. Well, if that's not tame, I'll go hopping!

Others:

1938: 'Well, I'll go hopping to H-----.
1941: Well, I'll go hopping to Hades.
1942: 'Well, most towns have their Bobby Burns statue, but I'll go hopping if I've ever seen one before with three of them!'
1943: WELL, I'LL GO HOPPING TO - SMELLIE'S and get some decent Gates to keep the I BIG THIEVING wows out of the Garden
1943: "I'll go hopping if I'd stand for that punk tune.
1946: 'Well, I'll go hopping to — . Where did she get to ?'
1947: 'Well, I'll go hopping to Hades,'
he said as he sat down. 'We've run
out of petrol.'
Answer: In a search of the National Library of Australia's Trove archives, I found a significantly earlier instance of "Well, Ill go hopping!" than the ones noted in Hugo's very useful answer. From Hugh Vernon, "Goblin's Adventure: A Midnight Experience: Story of a Street Arc Lamp," in the [Sydney, New South Wales] Sunday Sun (March 19, 1905):

Mr. Goblin was a man of extremely mixed habits, and this night in particular had been looking on the wine when it was red. Mr. Goblin was not only unsteady in his gait, but actually couldn't discern which of the keys on his key ring was the open sesame to his front door. "Dash it," ejaculated Mr. Goblin. "Why don't they have a light in front here?"
Then Mr. Goblin gave a jump that nearly sent him sprawling down the steps, for there just in front of him stood a man, dressed just like any ordinary man of the present day, but his clothes shone like the rays of the moon.
"Well, I'll go hopping," was Mr. Goblin's first remark as he recovered himself from the surprise.
"It Is very good of you, old chap, to give a whole King's Birthday illuminous display, on my behalf, but you'll get yourself into a devil of a mess by smothering yourself with phosphorus like that, and then look at the danger of it."

An unexpurgated version of the expression appears in Yussuf, "A Penny Ha'penny!" in the [Sydney, New South Wales] Smith's Weekly (December 9, 1922):

Entering the empty bar, he [Bill] called for half a pint of Bass, and put six-pence on the counter. The publican took it, and Bill swallowed the beer as it should be swallowed. He was just about to repeat the order when a bow-legged Cockney Tommy walked in; said: "'Arf a point o' Bass," and put fourpence ha'penny on the boards. When the beer was supplied, swallowed by Tommy, and the coppers transferred to the till without comment by the host, something seemed to happen to Bill's inside; his hair stood up, and his cheeks burned. He stupidly watched the soldier pull the door open and swing out, and then he found his voice: "Well, I'll go hoppin' to Hell!" "What's that?" queried Bung. Bill looked at him coldly, and his face was white now. "Half a pint of Bass!" he said. It was brought, quickly despatched, and the mug rattled on the counter. "Another half pint!" he ordered. The publican brought it, and while it was on the way to join its fellows, he said: "Y' haven't paid for t'other yet, sojer." Bill wiped his mouth with the back of a right hand whose knuckles were strangely knobbly; then, banging the same fist on the bar counter with a thump like a Minnewerfer going off, roared: "And I'm not goin' to pay for t'other or this one t'either! If you think I come 50,000 miles" (a few miles didn't matter to him) "to be robbed of a penny ha'penny by a pot-bellied Pommy pirate, you're on a loser, boy!"

This second instance instance is 17 years younger than the first, but journalistic discretion being what it is, I consider it as likely as not that "I'll go hopping to hell" was the original form of the phrase, and "to hell" got truncated or redirected to other destinations out of situational politeness.
As for "I'll go he," the Trove archives yield a slightly older instance than the one from 1912 that Hugo's answer notes. From "From Over West," a letter from Gwen Curry, writing from, Perth, Western Australia, to her Uncle Jeff, in the Albury [New South Wales] Banner and Wondonga Express (July 2, 1910):

The Johnson-Jeffries fight is also causing excitement. The little boys in the streets are betting with their pennies and half-pennies, as the men are with their pounds. All I have heard so far are for Jeffries. I heard one kiddie exclaim: 'If Jeffries does not win this fight I'll go he.' I know nothing about fighting, so I can't say if he will be 'he' or not. But last and not least is tho subject that is causing the greatest excitement, namely, tho cost of living.

There are, however, a couple of additional complications not mentioned elsewhere on this page. Starting in the early 1890s and continuing at least into the 1910s are instances of "I'll go you" used in the sense of "I'll take you up on that bet [or offer]," as we see in this instance from "Telling Time by an Heirloom," in the [Brisbane] Queenslander (December 12, 1891):

"But, really, is it reliable?"
"I oan tell the time to a half minute by it and swear to it. I'll bet I can come closer to the exact time than you now."
"I'll go you." He pulled out a handsome little stem-winder, glanced at it, and said: 'It's 12.33. Now get a crowbar and open your old safety-deposit vault and see what time you make it.'"

And again in this one from "The Humorist: Pinto Bill as a Publisher," in the Adelaide [South Australia] Observer (December 28, 1895):

"'Now I want a Business Manager,' I said, 'and you're just the man for that end of a newspaper. I never was any good at that. I can stick the type and write the editorials and the news, but I can't hustle for ads. and subscribers. You and I together could make a big thing of it.'
"'I'll go you,' he replied, and we made a bargain right there.

Second—and far more pervasive—is the expression "I'll go bail," meaning that "I am willing to bet." It appears in Australian newspapers going back at least as far as this instance from T. Crofton Croker, "Legends of the Lakes; or, Sayings and Doings at Killarney," in the Sydney Gazette and New South Wales Advertiser (August 22, 1829), in a story set in Ireland and reprinted from the [London] Mirror:

'O, but the day isn't over yet,' said Tom, 'so you'd better not halloo, sir, till you're out of the wood. I'll go bail we'll have rain some time of the day, and then you may be sure of it for the forty days.'"

Conclusions
My searches of the Australian Trove archives yielded instances of "Well, I'll go hopping!" from 1905 and of "Well I'll go hoppin' to Hell!" from 1922, as well as an instance of "I'll go he" from 1910. Whether the two expressions are closely related is unclear. The early "I'll go hopping" examples involve adults, whereas the first "I'll go he" example is explicitly attributed to a child. I see no reason to assume that "I'll go he" emerged directly from "I'll go hopping [to wherever]."
The meaning of "I'll go he" seems to be something like "I'll be shocked [if some specified thing happens in the future]." The meaning of "I'll go hopping," although similar in sense, seems cast much more in the present tense, and thus has a sense more along the lines of "I'm stunned" or "Well, blow me down!" This is borne out in the excellent examples that appear in Hugo's answer.
It is also possible that the usage "I'll go he" was influenced by the slang expressions "I'll go bail" (from the 1820s forward) and "I'll go you" (from the 1890s)—the former meaning, essentially "I'll bet" and the latter "I'll take you up on that." But if the wording "I'll go he" really emerged into the public record from early-twentieth-century Australian children's patois, nailing down its precise historical origin and antecedents may be very difficult indeed.


Does Microsoft Security Bulletin MS11-049 affect SQL Server 2008 SP3?

Question: The security bulletin does not list SQL Server 2008 SP3 under affected software but it came out prior to that service pack. We are running SP3 but this issue is still showing up on a vulnerability scan. Does anyone know for sure if this is a false positive? I only found one forum post where someone said SP3 "should" include this security update.
Answer: Scroll down to Security Update Deployment and open that up. Then open SQL Server 2008. You will see that SP3 includes this fix.
If your tool is reporting this problem because it doesn't detect the patch then one of the following is true:

The tool is wrong.
The tool has additional information not listed on that page.

If your tool is reporting the problem because it's using an exploit to test the vulnerability, then I would take that up with Microsoft.


How to make a time picker view in swift 3.0?

Question: I successfully make datePicker view over my  UITextField in Swift. But I need to time picking in the format of HH:MM:SS. I have no idea about it. I need to apply picked time in time UITextField. so, How to make Time Picker in Swift? please refer below image. swift 2.2 , 2.0 answers also okay. Thanks lot friends!
Answer: Updated for Swift 3:
If you want to show the time picker, use the lines of code for Swift 3 below:
Variable Declarations:
let timePicker = UIDatePicker()

Method Definition:
func openTimePicker()  {
    timePicker.datePickerMode = UIDatePickerMode.time
    timePicker.frame = CGRect(x: 0.0, y: (self.view.frame.height/2 + 60), width: self.view.frame.width, height: 150.0)
    timePicker.backgroundColor = UIColor.white
    self.view.addSubview(timePicker)
    timePicker.addTarget(self, action: #selector(yourViewControllerName.startTimeDiveChanged), for: UIControlEvents.valueChanged)
}

func startTimeDiveChanged(sender: UIDatePicker) {
    let formatter = DateFormatter()
    formatter.timeStyle = .short
    youtTextFieldName.text = formatter.string(from: sender.date)
    timePicker.removeFromSuperview() // if you want to remove time picker
}

Comment: problem with this is.... when you select hours and you had a sec of pause it will auto close it. anyone is trying to do this solution might want to add a flagging to the code of check if finish editting or make another viewcontroller using this method. code work. user experience need improvement. voted +1
Answer: Set the datePickerMode to time
Swift 3
self.datePicker.datePickerMode = .time

Swift 2.3 or lower
self.datePicker.datePickerMode = .Time

Note: This will allow you to only select Hours and Minutes, if you want to select Seconds also you need to go for custom time picker.
Answer: Added for Swift 5+
for timer (it doesn't show seconds part. )
@IBOutlet weak var timerPicker: UIDatePicker!
...
 self.timerPicker.datePickerMode = .countDownTimer
 print("countdown duration",  String(timerPicker.countDownDuration))


Why is /lib/libc.so.6 missing?

Question: find | grep libc.so.6

reveals that it's in /lib/i386-linux-gnu/libc.so.6, but a script I was running expected it to be directly under /lib, so why isn't there at least a symlink?
Would I risk breaking anything if I put a symlink there?
Answer: libc.so was moved as part of the multiarch work in Ubuntu 11.04.  The reason that there can't be a symlink there is that the purpose of multiarch is to make it possible to install both the i386 and amd64 versions of libc at the same time so that you can run 32-bit binaries more easily on 64-bit systems and vice versa (and other similar situations).  If the libc6 package contained a symlink to the new location, then the versions of that package for different architectures wouldn't both be installable at the same time (which version of the symlink would dpkg pick?), defeating the entire point of the exercise.
Anything that hardcodes the path to libc.so must be updated to work properly from Ubuntu 11.04 onwards.  If the script you're talking about is part of Ubuntu, please report a bug on it and add the multiarch tag.
Comment: If you're never going to use 64-bit packages, I doubt there's any significant risk in adding a symlink, no.
Comment: Nice answer, learned something new today (again) :)
Comment: The processor I'm using doesn't even support 64 bit instructions. Would you say there's any risk associated with manually adding a symlink? Not sure I need to do that, but if. Anyway, this seems to be the correct answer. Thanks.
Comment: @Erik B: what? Are you telling me you're trying to use a 64 app on a 32 bits processor? That's definitely **not** going to work. 32 bits apps work fine on a 64 bits processor, but not vice versa.
Comment: @Lekensteyn that's definitely not what I'm saying. What I'm saying is that I have no use for the 64 bit library. So on my particular system there's not going to be any confusion about whether `/lib/libc.so.6` is the 32 or 64 bit library.
Answer: Dynamic libraries are loaded by the kernel, the paths are not hardcoded in a program. A program just says "I need libc.so.6". The system then searches in library paths as defined in /etc/ld.so.conf, including /usr/lib and /lib by default. This file includes additional configuration files in /etc/ld.so.conf.d.
On my 64 bits system, libc.so.6 can be found in /lib/x86_64-linux-gnu/libc.so.6 because of the path defined in /etc/ld.so.conf.d/x86_64-linux-gnu.conf:
# Multiarch support
/lib/x86_64-linux-gnu
/usr/lib/x86_64-linux-gnu

To find out what library is loaded by a program, use ldd as in ldd /bin/bash:
    linux-vdso.so.1 =>  (0x00007ffff1dff000)
    libncurses.so.5 => /lib/libncurses.so.5 (0x00007f9d8b3b8000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f9d8b1b4000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9d8ae1f000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f9d8b61c000)

Putting the symlink would not break anything.
To get a list of directories that are searched, run:
ldconfig -v -N | grep '^/'

-v causes a list of file + directories to be shown, -N prevents the cache (/etc/ld.so.cache) from being recreated.
Comment: Putting the symlink would not break anything, but it wouldn't really do anything good either, right?
Comment: @Erik B: what program / script are you referring to? I can understand that a script gets confused because the path is hardcoded. But a program does not have to know the path.
Comment: Is that how it works? I seem to have issues sometimes where programs cannot find libraries installed in `/usr/local/lib`, but they work fine if I make a symlink from `/usr/lib`. What causes this behavior?
Comment: @crazy2be: can you post the output of `ldconfig -v -N | grep '^/'` ?
Comment: @Lekensteyn: Sure: http://pastebin.com/dtfnw2Tv. It's happened with some programs on almost any system i've used, however, so I assumed it was not related to system configuration.
Comment: @crazy2be: what's `/usr/local/lib/libstdc++.so.6.0.14-gdb.py` doing there? Only shared libraries (`*.so`) should be placed there and their symlinks with version information (`*.so.x`, `*.so.x.y` and `*.so.x.y.z`). I think that file is an installer, not actually a shared library.
Answer: Just add symlink to the libc.so.6 file as following:
sudo ln -s /lib/i386-linux-gnu/libc.so.6 /lib/libc.so.6

The same goes for other missing files still on the system, in my case Matlab was missing the file, the problem is gone now.

Why is /lib/libc.so.6 missing?


Does ARIMA assume evenly-spaced data in statsmodels?

Question: I've read that ARIMA assumes that endogenous input array is evenly spaced. If that is the case, then what is the point of the dates parameter in statsmodels.tsa.ARIMA(), which seems like it is there to support irregularly spaced data? Also, what are the assumptions for the optional exogenous arrays, need these be spaced in the exact same way as the endogenous?
Comment: The only application of irregular time series I know is in "nowcasting" in macroeconomics. They use statespace models for this, as far as I know. Although the new statespace models in statsmodels allow for missing values, I don't think irregular time periods would work out of the box.
Comment: To add to @AlaskaRon's answer, the `dates` parameter might not mean much; perhaps it is useful when plotting as it helps create relevant scale of $x$ axis. It does not mean the function supports irregularly spaced data (although I do not work with Python, so I cannot fully guarantee this is the case).
Comment: `dates` are also used to allow users to select time periods for prediction or forecasting using dates instead of indices.
Answer: Models written in terms of lagged variables (which ARIMA is) work only on equally-spaced time periods.  If the data was irregular and worked in this function, you would have to specify a correlation function (such as exponential correlation, gaussian correlation, etc.), as you do in geostatistical models.  The dates parameter is only for plotting purposes.
The exogenous arrays usually are spaced the same way as the endogenous, because they are basically explanatory variables in a regression that explains the endogenous variable, so it usually would not make sense for them to be collected at different times (there are exceptions, such as when you collect the exogenous variable at a different frequency and match them with the closest date for the endogenous variable (i.e. you have yearly GDP measurements you are using to predict monthly local unemployment values), or where you use lagged exogenous variables (i.e. using precipitation from last year and the year before to predict tree growth this year, with the non-independent error terms modeled by the ARIMA model).


How do I create a shader that is partially emissive for a particular colour, but diffuse if it's grey?

Question: So, I'm trying to make some material that's like lava, with solid, diffuse, grey material, and an emissive shader that's red and orange, using a musgrave and colorramp node. This is a screenshot. How would I accomplish overlaying the the bright emissive parts over the black diffuse? Would I use a transparent colourramp or something?
This is a screenshot:
Comment: At least one thing to change is to use a mask when mixing **Emission** and **Diffuse** shaders. At the moment you have that emission gets less "emissive" and more grey because of grey shader, while grey shader gets brightness from emission (they are mixed by half with each other). Plug a mask into the *Factor* input of the **Mix**  shader and your lava should get more obvious shading. You can make a mask nearly from anything, but at the starting point that musgrave texture should be good.
Answer: You need to plug another texture in the Fac port of the Mix Shader node, it will separate the emission and diffuse shaders, like so:


Does IIS 7.5 server farm need to be on a Domain? 2008 R

Question: We are using Server 2008 R IIS 7.5 with an SQL DB on the backend. At the moment the system is working fine with three of the servers configured in a load balancing farm while communicating data back to the SQL DB. All of these servers are free standing on their own subnet with a common admin and password. The question is… is there an advantage for making one server a PDC and creating their own domain and joining the rest of the remember servers to the domain?
Answer: I investigated this when setting up a similar web farm and all of the resources I queried said that for security reasons you should definitely not join web servers in a DMZ with a domain on a private network.
Most resources also suggested that it wasn't a great idea to create a separate domain in your DMZ for the web servers.
So I opted to do the same thing and just have stand alone servers that share admin username and password and I've been running them for over a year and have no regrets about my decision.


Action sequence in Cocos2d

Question: I have an array of sprites. I want to loop through the array and tell each spirite to move a certain distance at a random angle, and fade out while doing so. Preferably with easing. Is there a way to set up a sequence to do this? Can you have a mutable sequence where you can add actions as you loop through the sprite array, and then run the sequence once you're done adding all the actions?
Comment: You may want to look into the Particle System functionality of cocos2d. It sort of sounds like you are trying to build something that may already exist.
Answer: I don't understand your question so well but maybe this example can help you:
<code>CCArray *spritesArray; //array with sprites

float timeToMove = 1.0;
float timeToRotate = 1.0;
float timeToFadeOut = 1.0;
CGPoint initialMovePos = CGPointMake(100, 100);

for (int i = 0; i<[spritesArray count]; i++) {
    id moveDistance;
    if (i == 0) {
        moveDistance = [CCMoveTo actionWithDuration:timeToMove position:initialMovePos];
    }else{
        CGPoint lastSpritePos = ((CCSprite *)[spritesArray objectAtIndex:(i-1)]).position;
        moveDistance = [CCMoveTo actionWithDuration:timeToMove position:ccpAdd(lastSpritePos, CGPointMake(10, 10))];
    }

    float angleToRotate = random()%360;
    id rotateAction = [CCRotateTo actionWithDuration:timeToRotate angle:angleToRotate];
    id fadeOutAction = [CCFadeOut actionWithDuration:timeToFadeOut];

    CCSprite *sprite = [spritesArray objectAtIndex:i];

    [sprite runAction:[CCSpawn actions:moveDistance,rotateAction,fadeOutAction, nil]];
}
</code>

Action sequence in Cocos2d


How are related banners used with promotions?

Question: Documentation of this feature is very sparse. Basically, I want the ability to dynamically display a banner on the cart/checkout pages when a certain product is in the cart. Is this what related banners are for? If not, what is their function?
Answer: Banners and promotions work as such:

Banners can be associated to Promotions, and displayed only when a promotion is active
Banners can be associated, via a promotion, to a customer segment

From the Magento EE User Guide:

Related Promotions – This tab includes one grid containing all your existing Shopping Cart Price Rules, and one grid containing all
  your existing Catalog Price Rules. Select the checkbox next to a Price
  Rule to associate it. You can associate this Banner to multiple
  Shopping Cart and Catalog Price Rules simultaneously. If the Banner is
  associated to any price rules, it will only display when that rule is
  applied (the price rule is active and the conditions in the rule have
  been met). You can also associate a Banner to a Price Rule via the
  Price Rule page. For both Shopping Cart and Catalog Price Rules, there
  is now a Related Banners tab in the Price Rule page. This tab includes
  a grid containing all existing Banners, which can be associated by
  selecting the checkbox next to the Banner.

And from the section regarding customer segmentation:

Banners – To associate a Segment to a Banner, navigate to CMS > Banners, click Add Banner or select an existing Banner from the grid,
  and select Specified from the Customer Segments dropdown. This
  will open a multi-select menu including all existing Segments. You
  can associate multiple Segments to a Banner.
Comment: Correct - but what I have done is create dummy rules with no discounts for banner display only, specifically for means of promoting upsells.
Comment: OK, for example let's say I have a cart promotion where if productA is in the cart, productB and productC are eligible for a discount if they're added to the same order. In order to advertise that promotion I would actually have to create a separate promotion with related banner that only required productA to be in the cart but applied no discount. In other words, the full ruleset has to be satisfied in order for a related banner to display. Does that make sense and is it correct?
Comment: I think we're saying the same thing, or did I get something wrong in my first comment?
Comment: Ha, no you're right - I misread it. We're on the same page.
Comment: So, if I read correctly: [ Promotions > Price Rule > Related banners ]  and [ CMS > Banners > Related Promotions] accomplish exactly the same thing, or is there a difference in the business logic they apply?


SH2016 patch config Wiz error

Question: I am trying to implement the new Jun patch on SH2016 farm and when I try to run the config Wiz I get an error unable to upgrade [searchAdminDatabase] failed and the reason it's looking for a user account which was disabled, when I checked the DB owner I noticed all search, profile, Social, state service, sync, Wss_usageapplication DBs are owned by this account, it looks like this account was used to install SHP. All other DB are owned by Farm account.
I tried to change the ownership of these DBs to Farm account in SQL but did not fix the problem. My question is there a way to change the DB owner to continue or I have to install SHP again.
Answer: You should not disable the service account that was used to install SP, this can cause all kinds of issues.  Also it is typically recommended that you use this installer service account to install CUs.  For quick fix, if this is possible,  I'd enable the service account and try the wizard again.
Comment: I totally agreed with you but unfortunately it was installed by someone else and that person used his personal account to install it instead of using a service account. So I am looking for solution to replace this account with a service account if possible.
Answer: I hope you have changed the farm account from the Central Administrator site as well.

Go to Central admin
Open Security page and click on Service Account, from the drop down change the farm account to the new account. Run IIS reset and restart SharePoint time job.

SH2016 patch config Wiz error


Is it illegal for a fitness center to deny my request for a copy of my contract? Also is it illegal to cancel a membership via phone in Tennessee?

Question: I tried to cancel a gym membership over the phone and was told by the girl it would be taken care of. Then I end up in collections for not paying dues. The gym is telling me it's illegal to cancel a membership over the phone. Is this so? Also they won't provide me a copy of my contract.
Answer: It is not illegal per se to cancel a contract over the phone, or by any other means of communication. The contract itself might, however, require that a cancellation be done in writing, must be hand-delivered, or whatever it says. You would have to look at the contract to see what the conditions for cancellation are.
When you first enter into a contract, you have an opportunity to get a copy of the contract, for example you walk into the facility and sign an agreement, and you should then be given a copy. But it is possible that they will fail to give you a copy, or they might even refuse to give you a copy. It is possible that, as a consumer, the law of your state requires businesses to give copies of contracts to customers. If not, then this is the situation where you had a choice to agree to their offer only if you get a copy. If they intend to take you to court for breach of contract, they will have to provide a copy in order to prove to the court that you have violated the terms.
Even if the contract says that contract cancellations must be by certified mail delivered to Nepal, the company will be held responsible for the representations of their authorized agents. They might try to introduce the contract into the dispute, but you can prevent them from doing that, using "promissory estoppel", because in effect you relied on their promise to cancel the contract. Their best hope is to dispute your claim that their agent made such a promise.
Answer: In line with user6726's answer, the real problem is that the gym is likely to deny that its employee accepted your notice of cancellation over the phone.
If you haven't done so, request in writing (by email or having the gym sign a receipt of your request) a copy of the contract. Evidence of the gym's (I wold say unreasonable) refusals to provide you with a copy tends to prove that the gym is departing from the implied covenant of good faith and fair dealing that is expected in contract law.
To illustrate the potential relevance of the gym's refusal, see Resource Management Co., v. Weston Ranch, 706 P.2d 1028, 1048 (1985):

One additional finding, pertaining to the Westons' understanding of
  the contractual terms that should be addressed, is the trial court's
  finding that Stevenson refused after the September 20 meeting to give
  a copy of the contract to George Weston for examination and that as a
  consequence none of the Westons had a full understanding of the
  contract's terms. [...] There is no evidence in the record indicating
  that George Weston asked for a copy of the contract following the
  principal September 20 meeting, much less any evidence indicating that
  Stevenson refused such a request.


Strange escape sequences in terminal

Question: I have kitty, and I use nnn as file manager.
I actiavted the "preview-tui" plugin in nnn.
When I hover over a folder, I see something like this:

What are those strange escape sequences?
Answer: The <ESC>[...m escapes are color codes. It looks like you're looking at the output with less (or the tools are running less for you).
less can be made to display the colors with the -R option. I.e. less -R, or set the LESS environment variable to include R (among any other options you need). You can get similar issues with git, if you have the LESS envvar set, but without including -R.

Strange escape sequences in terminal


How do I get the actual boot image file from a block device without padding?

Question: I have 9.6mb file that after doing dd if=/dev/zero of=/dev/block/mtdblock2 I write to mtdblock2. Before writing I have done a sha1sum on the file. I can use applypatch -c to check both size and sha but if I do a sha on the blockdevice it is of course different because of the space left on the device. If I copy the device I will get a 16mb image including that free space. Every where I read the suggestions are to use fdisk to get a count and then use the count option in dd. However, this does not work because the block and partition is the boot partition. How can I copy the original file, same size and sha, back off of the block device?
Comment: Not clear what you are asking. If you already know the size (9.6mb; is it 9.6MB or 9.6MiB?) just do `dd if=/dev/block/mtdblock2 of=boot.img bs=9.6M count=1`. `bs=9.6M` is `9.6*1024*1024` bytes. `bs=9.6MB` is `9.6*1000*1000` bytes. Use whatever applicable to your case.
Comment: you know what /dev/zero is? you destroyed boot already, no way to get back
Comment: @Irfan Latif - The file I have is 9.6mb but the file I'm trying to extract maybe and probably is a different size. It's proprietary and signed. I need the image file itself to get the sha1sum so that I can use applypatch on it.
Comment: So you are looking for `boot.img` format. See official documentation: https://source.android.com/devices/bootloader/boot-image-header and how `magiskboot` extracts `boot.img`: https://github.com/topjohnwu/Magisk/tree/master/native/jni/magiskboot. It's very device-specific.
Answer: I would indeed use dd, with one or more of the several options available to specify the length (amount) of data to copy; otherwise, as you have noticed, dd will read the entire contents of the device, which is not what you want.
Re the apparent problem of the block device being the boot partition, the usual solution is to boot from some other medium (perhaps a LiveCD) so that the device you want to read is not the boot device/partition and can be read without difficulty.  Before that, though, try sudo dd ... and see if running as root solves the problem without requiring more drastic measures.
Comment: 1) Boot partition is read-only. It's loaded in memory only once by the bootloader. After that it's no more in use. And even if it is, reading a raw block device is always possible. 2) How would you boot an Android device from LiveCD or any other medium?
Comment: Taken literally, (1) is a little different than I'm used to on platforms I know better than Android, but still means OP should have no problem. Since he says he does*, I hypothesized that "maybe Android is different."

Too, Android runs on so many different devices that maybe OP's device *can* boot from CD --or maybe a thumbdrive if you prefer.  I've never seen anybody run a command-line shell, or dd, on Android before ; so, if he can do that, I can't assume anything is impossible.

Bottom line, I think my basic points still hold, as far as they go.
Comment: Just if you are interested to know in detail what I meant: https://android.stackexchange.com/a/220678/218526. Concepts of booloaders, boot partition and booting are entirely different on Android devices as compared to normal Linuxes or other OSes.


Finding the period of an infinite length pendulum

Question: What would be the period of a pendulum with an infinite length, assuming a non-rotating Earth? The answer is not infinity.
Comment: Well, the limiting case of a mathematical pendulum of finite length would suggest that the period would tend to infinity. If you say it's not infinity, what kinds of assumptions are we allowed to make here? I mean, an infinitely long pendulum would rupture under the weight of its string. Is that supposed to be the answer?
Comment: Heck, while we're at it, what if the Earth is rotating infinitely fast instead?
Comment: I presume you are expected to calculate the result not in a uniform field as we do with reasonably sized pendulums (in which case the period does grow without bound) but with the full spherical field and neglecting the mass of the rod.
Comment: @dmckee how does the field falling off with height help? Wouldn't this "softening" just make the problem worse?
Comment: @NowIGetToLearnWhatAHeadIs It's not that it falls off with height, it's that there is a residual change in *direction* of the field. You can't use the analysis that we use on the finite length pendulum because the rod always points in the same direction.
Comment: I think the part about nonrotating earth is to avoid the engineering issue of a tangled and ever shortening pendulum :X
Comment: either way it doesn't make sense--a pendulum at infinite distance experiences no return force because it has zero potential energy.
Comment: @gregsan No, it expereinces a return force because the field from the Earth doesn't point uniformly down (except in a small lab), it points toward the center of the Earth. I'll undelete my answer later on if you want to see how I worked it.
Answer: Well the pendulum bob, moves in a straight line, and if we presume that the bob is effectively in a vacuum, or is heavy enough for air resistance to not matter, and the path is basically at the earth surface, it would seem that the period is effectively independent of the pendulum length for lengths many times the earth radius.
I can't be bothered to work out the answer, which should be relatively simple; but I am prepared to give you a WAG answer.
I believe the period is 84 minutes or thereabouts, provided of course the amplitude is a small value compared to the earth radius.
Now, 84 minutes just happens to be the period of a simple pendulum, whose length is equal to the earth radius.  It is also the orbital period of an earth satellite orbiting essentially at the earth surface (no air resistance).
Moreover, if you drill a hole between any two points on the earth surface, close enough together that the center of the hole is not too much below the surface as a fraction of the earth radius, then the transit time for a round trip between those two points in say a straight evacuated frictionless tube, is also 84 minutes.
So I don't distinguish between the tube case, and the infinite pendulum case, so I say the answer is 84 minutes.
People who make inertial stable platforms (gyro stabilized are familiar with a "hum" instability in their systems, that has an 84 minute period.
Answer: I choose to put the "centered" position of the bob over the north pole, and have the z-axis point upward through the pole. The bob swings in the x-z plane, with it's point of closest approach at radius $r_c = r_e (1 + \epsilon)$.
The gravitational force acting on the bob, in the limit of small oscillations is $ -mg(\hat{z} + \frac{x}{r_c}\hat{x}) $, and the rod provides $+mg\hat{z}$ leaving a residual of $F = -x\frac{mg}{r_c}\hat{x}$ so this arrangement is a harmonic oscillator with $k = \frac{mg}{r_c}$.
The usual solution applies giving $\omega = \sqrt{\frac{k}{m}} = \sqrt{\frac{g}{r_c}}$. That gives me a bit over 5000 seconds for small oscillations near the surface. This agrees with George's analysis.
Cute problem. As usual the process is more important here than the result.


Does using '&' versus 'and' matter for SEO

Question: When creating web page titles, is there any difference between using the word 'and' in the title compared to using an ampersand?
Comment: I'm pretty sure `and` is a stop-word in every serious search engine.
Comment: @Damon Searching with and without `and` in a search phrase does yield different results in the big G, so it's not simply being filtered out as you might expect with a traditional "stop word". Google does make use of "natural" search algorithms so `and` might have a role in this respect?
Answer: & (ampersand) and the word 'and' are treated similar but can yield different search results (although often, very similar). The two might result in the same verbal sound 'and' but they do represent different contexts.
If I were to use the following page title:-
We have the best socks on the planet and they're colourful!

It wouldn't make sense to convert 'and' to '&' like:-
We have the best socks on the planet & they're colourful!

That isn't correct use of the English language.
An '&' represents a joining in a heading/category/title for example...
Health & Beauty
Bed & Breakfast

Granted however, these would still work as:-
Health and Beauty
Bed and Breakfast

Really, you need to be conducting your own tests and research because how these will be treated in organic search will largely depend upon the context and topic/words in use.
Comment: Thank you. I guess the key question (which I should have clarified) is not just 'does it matter' but 'is there a reason for doing one over the other'?
Comment: "That isn't correct use of the English language."

How do you figure that? The ampersand is completely equivalent to the word "and".
Comment: @Ryan M - Whilst ampersand might mean 'and', it is [certainly not acceptable to use it instead of the word 'and' in most cases](http://english.stackexchange.com/a/3145) of formal proper English.
Comment: @GeoffJackson-zigojacko It is, like a lot of abbreviations, informal. This is a matter of style, though, not correctness. The ampersand is definitely not an "[in]correct use of the English language," any more than the "they're" contraction is in your example. If the page title is intended to set a formal tone, I wouldn't use either of them. But neither are grammatically incorrect.
Answer: Search engines are going to know that & and and are synonymous, so there is certainly going to be some overlap in the results.
However, searching for hello & welcome verses hello and welcome in Google does return different results (which also differs from hello welcome) - so yes, it does affect SEO.
Answer: As already mentioned the two are recognized as the same word by the search engines but actual search results will vary.
Both the word and the ampersand symbol have a place in web copy from an SEO perspective.
And
I would suggest using the word "and" in your body text.  This is how most people will search and you have a highly likelihood of connecting on an exact match search phrase in doing so.
Using the full word in your copy is also the proper use of the English word which would be deemed as "higher quality".  Proper grammar and spelling is thought to be factored into the Google algorithm by many in the industry.  Matt Cutts discusses it here.  Notice he mentions bad grammer in comments will not have an impact.  The emphasis here is "in comments", he does not mention the author's copy and sugggests it should be "high quality".
The full word can be used in a title but there can be some advantages of using the ampersand instead.
&
The use of an ampersand is something I would recommend using in the meta title tag and content headlines.
With regards to the meta title tag, using an ampersand can be helpful from an SEO aspect because it is shorter than the full word and can be used to create a higher response title.
The meta title tag is typically limited to 70 characters before it is cut off or truncated by search engines.  Advice will vary on best practices but I have found it best to keep my meta title tags as short as possible while clearly conveying the topic in a natural sounding phrase.  While I can not be certain that shorter meta title tags are rewarded, the shorter (precise) title does give the searcher a clear, fast and easy to discern topic for the page.
The use of the ampersand to make a meta title or content title more attractive can also have merits for SEO through user engagement.  The job of a search engine is to offer the most relevant results which is best measured with metrics such as search click through rate, bounce back rate, time on site and pages per visit.  These metrics matter and are all part of the Google Panda quality algorithm in some fashion.
The search click through rate is influenced by copy in the meta title tag. Page views per user can also be impacted by related or additional content headlines used on-site.  As the ampersand (and other symbols) are commonplace in direct response and news copy headlines (both used to get response) it would make sense that it could be helpful in the same application for SEO through user engagement metrics.


Revisiting development of Solow Model with no population growth and no technical progress

Question: Consider an economy descried by the production function:  = (, ) = 0.30.7.
a) Derive the per-worker production function.
b)Assuming no population growth or technological progress, find the steady-state capita stock per worker, output per worker and consumption per worker as a function of the saving rate and depreciation rate.
Comment: What's your question? and what trouble are you facing with the problem?
Answer: You can use the following results provided below to try and answer the problem yourself.

Consider a Constant Returns to Scale(CRS) production function $F:\mathbb{R}_+^2\to \mathbb{R}$
Let $Y=F(K,L)$ denote the level of output produced using $K$ units of capital and $L$ units of labor given the production function $F$.
By CRS, $F$ must satisfy $: \quad F(\lambda K, \lambda L)=\lambda F(K,L)$ where $\lambda \geq 0$ is some constant
Since the above holds for any positive $\lambda$, we can set $\lambda=\frac{1}{L}$ and let $k=\frac{K}{L}$ and $y=\frac{Y}{L}$.
This gives us:
$$\begin{eqnarray}
& F\left(\frac{K}{L},1\right)=\frac{F(K,L)}{L} \\
& F(k,1)=\frac{Y}{L} \\
& y=f(k) && \text{where }F(k,1)\equiv f(k) \tag{*}
\end{eqnarray}$$
The expression $\boxed{y=f(k)}$ is known as the intensive form (per-worker production) function (which is what you are asked to find in part a)

Consider a Solowian Economy with the following features:
$\bullet$ Time is continuous and there is no distinction between the labor force and the population at any given period of time. Labor (or population) growth rate $\frac{\dot{L}}{L}=n$  , where $\dot L= \frac{dL}{dt}$ is exogeneous
$\bullet$ In each period a constant proportion of income $s\in(0,1)$ is saved and capital depreciates by $\delta$ in each period
$\bullet$ There is no technological progress and output in any period is given by $Y_t=F(K_t,L_t)$ with the assumption that $F$ satisfies all the properties of a neo-classical production function
Denoting the growth rate of any object $x$ (say) as $g_x$ let us use the above data to solve for the steady state.
The law of motion of capital is given by: $\begin{eqnarray} &\dot K = I-\delta K\\
\implies &\dot K= sY-\delta K \tag{**} \end{eqnarray}$
we defined per-capita capital as $k=\frac{K}{L}$ and at steady state we must have $\frac{\dot k}{k}=g_k=0$ i.e., the growth rate of per-capita capital must be zero at the steady state. Let us find an expression for $\frac{\dot k}{k}$ or $g_k$ as a function of $k$ in order to find steady state per-capita capital.
$$\begin{align}
k&=\frac{K}{L} \\
\ln k&= \ln K -\ln L & \text{taking log on both sides} \\
\frac{\dot k}{k}&=\frac{\dot K}{K}-\frac{\dot L}{L} & \text{taking time derivative on both sides} \\
&=\frac{sY-\delta K}{K}-n & \because \; \frac{\dot L}{L}=n \text{ and using (**)}\\
&=s\frac{Y/L}{K/L}-(n+\delta) \\
&=\frac{sy}{k}-(n+\delta)=\frac{sf(k)-(n+\delta)k}{k} & \text{using (*)}
\end{align}$$
$$\therefore \quad g_k(k)=\frac{sf(k)-(n+\delta)k}{k}$$
The steady-state per-capita capital is given by $k^*$ such that $g_k(k^*)=0$. Which can be obtained as follows:
$$\begin{eqnarray} &g_k(k^*)\overset{set}{=}0 \\
&\boxed{sf(k^*)=(n+\delta)k^*}\tag{1} \end{eqnarray}$$
A solution to $(1)$ will give you the steady state $k$ which in this case must be unique because of the assumption we made about production technology $F$ being neo-classical.
Once you have found out the steady-state capital per-capita $k^*$, we can use $(^*)$ to find the steady-state output per worker and consumption per worker.
steady-state output per worker: $\boxed{y^*=f(k^*)}$
steady-state consumption per worker: $\boxed{c^*=(1-s)f(k^*)}$
Answer: To find the per-worker production function we need to divide the given production function with L i.e. $\frac{F}{L}$  = $$\frac{K^{0.3}L^{0.7}}{L}$$ $$y=\frac{K^{0.3}}{L^{0.3}} = k^{0.3}; k =\frac{K}{L}$$ This completes first part of the question.
For the second part, we have to recall the key equation of the solow model i.e.,
$$\dot{k}= sk^{\alpha}-(\delta+n+g)k$$
As stated in the question growth rate of population and technology is 0,  $$\therefore n = g = 0$$
Which transforms our equation into $$\dot{k}=sk^{\alpha}-{\delta}k ; {\alpha} = 0.3$$
We know at steafdy state $\dot{k}=0$ therefore the above equation trandforms into
$$sk^{0.3}={\delta}k$$ $$\Rightarrow k^{0.7}=\frac{s}{\delta}$$ $$\Rightarrow k= (\frac{s}{\delta})^ \frac{1}{0.7}$$ and since output per worker i.e. y = k0.3
$$\therefore y = (\frac{s}{\delta})^{\frac{0.3}{0.7}}$$ and since consumption per worker $$c=(1-s)y$$ $$\therefore c= (1-s)(\frac{s}{\delta})^{\frac{0.3}{0.7}}$$
Comment: hey, it's against the homework policy to provide answers to problems that show no attempt


Adding DatePicker Bootstrap and Centering Simple_Form_For

Question: This is my form for now in my new_html_erb.
We are doing a promotion for the next two weeks
<%= simple_form_for @subscription, :html => { :class => 'form-horizontal'} do |f| %>
    <%= f.input :manual_expiry_date %>
    <%= f.association :user %>
    <%= f.button :submit, :class => 'btn btn-primary'%>
<% end %>

I have used twitter bootstrap on and off. The form that I am working on for a rails application is using bootstrap.
How do I add bootstrap datepicker to manual_expiry_date ?
How do I center my simple_form_for?
I have tried putting the form in a container, then a row, then adding form control all in divs. There was no marked change. I have tried adding it as a class to simple_form but still the same.
Thank you for the help.
Answer: Twitter Bootstrap dont have in his core a date-picker, buy you can use "DatePicker For Bootstrap" www.eyecon.ro/bootstrap-datepicker/
You need to specify the class of the object
<%= f.input :manual_expiry_date, input_html: { class: 'date_picker' } %>

and then
$('.date_picker').datepicker()

Comment: You mean `$('.date_picker')`?


Is the market price of risk subjective?

Question: Assume a model defined in a incomplete market. Assume that model contains some parameters $\theta_1 ... \theta_k$. In a risk neutral setting, one more parameter appears into the modeldynamics which is $\lambda$ (also known as the market price of risk). The market price of risk is unobservable. Does that mean it is subjective? If I am less risk averse than you, is my $\lambda$ then different from yours?
Answer: In an incomplete market model, some risk factors are not traded. Hence, while you have a clear idea of how the market rewards traded risk factors (assuming parameter values and the data generating process are known), you do not know exactly how untraded risk factors are priced.
One way to close the loop and fall on a unique price is to posit a representative investor and use the pricing kernel implied by their preferences. Another is to motivate a choice of a pricing kernel using reduced-form evidence. Either way, your problem with market incompleteness is that you don't have enough assets to infer a uniquely correct way of putting a price on all sources of risk, even in the absurdly optimistic setting where you know the "true" model.
Heston (1993) invokes a partial equilibrium consumption-based model to pick a pricing kernel. His model involves stochastic volatility, hence as long as the volatility disturbances aren't perfectly correlated with the equity disturbances, there is an infinite number of valid prices you can put on volatility risk using prices on options, the underlying and a risk-free proxy. But, if you are disposed to say that Heston's consumption-based argument is sound (i.e., you limit yourself to a sufficiently narrow class of equilibrium models), you have just one price and one risk-neutral measure that works. A similar thing applies to GARCH-based option pricing models as in Duan (1995), Heston and Nandi (2000), etc. with the exception that here the incompleteness stems from discrete dynamics.
Now, if you want an example of a reduced-form argument, Christoffersen, Heston and Jacobs (2013) used evidence on the shape of the pricing kernel on the S&P500. If you recall the Radon-Nikodym derivative, you essentially are looking at the ratio of the risk-neutral to the physical density. You can estimate the former using the Breeden and Litzenberger (1976) results and, for the later, you could use a parametric GARCH model and empirical errors as did, for example, Rosenberg and Engle (2002). Taking the difference of their logarithm on a year per year basis, you find clouds of points that draw a U -- i.e., your pricing kernel should be exponentially quadratic as opposed to exponentially affine as in a classical consumption-based model. CHJ2013 use it to motivate a quadratic pricing kernel for GARCH-based models. So, that's another way to pin down unique prices.
Now, from the broader perspective of what really happens in financial markets, if you think that equilibrium models are a good approximation or a good description of what is going on (in that, we just have the wrong equilibrium models, but the idea is sane), then there is a unique (though perhaps time-varying) price for every single sources of risk. The hope is that the choices you make in incomplete market models is "close enough" to that "true" price to be usable. If you rather think that those models are very crude description of otherwise chaotic and stochastic responses that emerge from the micro structure of markets, it's not obvious that anything you see in quantitative finance even makes sense. For starters, adding noise in chaotic systems can easily generate fat tailed conditional distributions and those distributions do not have finite variance, let alone finite covariances.
Comment: To add a bit to this well reasoned answer. The MPR is most often found as a degree of freedom in a model; hopefully that model is sound enough so that we could agree on it...  to reply to the other part of the question: Markets 'aggregate' heterogeneous beliefs and risk aversions in the market (that's what we might also call supply and demand...). There are a number of papers out there showing that this aggregation behavior (RAs->equilibrium) is mathematically feasible ... and that the heterogeneity of investors can last for a long time (no 'quick' squeeze out of 'too-risk-averse' players.
Comment: @Kermittfrog What kind of aggregation are we talking about here? In macroeconomics, an exact aggregation property would mean that there exist a DSGE model with a single representative household which is 100% equivalent to the DSGE model with heterogeneous households. Approximate aggregation à la Kursell and Smith would mean that representative household version is very close to the heterogeneous one and that you can think of it as 'the mean household behavior' is 'enough' to summarize aggregate dynamics... I suspect you mean something different here and would be interested in some references.
Comment: I am referring to those heterogeneous beliefs papers in the behavioral corner of the asset pricing universe. I'll look up some references. The core idea was that the notion "rational investors drive others away" may take a long time to really show.
Comment: @Kermittfrog I have seen some papers like this. I see what you're saying now. Thanks for the details.

Is the market price of risk subjective?


Tensorflow 2.0 keras fit overrides the "training" parameter in call function

Question: When creating a model using tensorflow 2.0 I am getting two different behaviours depending on how I do a forward pass:
1) If I do the forward pass using model(X) then it is fine and the "training" parameter in the call method works normally
vs.
2) If I use model.fit(X, y) to run the model instead then the "training" parameter seems to get overriden and set to None regardless of whether its default is True or False.
Does anyone know why this is happening? It means for example that I can't set up the model so that dropout only occurs when training is set to True.
!pip install tensorflow-gpu==2.0.0-alpha0
import tensorflow as tf
from tensorflow.keras.layers import Dense, Flatten, Conv2D
from tensorflow.keras import Model

X = np.random.random((250, 5))
y = X[:, 0] > 0 * 1.0

class MyModel(Model):

  def __init__(self):
    super(MyModel, self).__init__()
    self.dense1 = tf.keras.layers.Dense(4, activation=tf.nn.relu)
    self.dense2 = tf.keras.layers.Dense(5, activation=tf.nn.softmax)
    self.dropout = tf.keras.layers.Dropout(0.5)

  def call(self, inputs, training=True):
    print("Training ", training)
    x = self.dense1(inputs)
    if training:
      x = self.dropout(x, training=training)
    return self.dense2(x)

model = MyModel()

Then this prints out Training True as expected:
model(X)    # prints out: Training True

But this prints out Training None ?
model.compile(optimizer='adam', loss='mse')
model.fit(X, y, epochs=1)   # prints out: Training None

Answer: This was a bug:

The training value of tf.keras.Model.call() becomes None when
  tf.keras.Model.fit(). (tf2.0.0-alpha0)

https://github.com/tensorflow/tensorflow/issues/27275
Answer: This was resolved in newly released TF2.0.
Please replace !pip install tensorflow-gpu==2.0.0-alpha0 with !pip install tensorflow-gpu==2.3 in the above code. Please check the gist here. Thanks!
The output is shown below.
model.compile(optimizer='adam', loss='mse')
model.fit(X, y, epochs=1)   # prints out: Training None

Training  True
Training  True
8/8 [==============================] - 0s 1ms/step - loss: 0.6448
<tensorflow.python.keras.callbacks.History at 0x7f1f5961edd8>


What are the licence implications of including comments from code licensed under GPL v2 in my own code?

Question: I have written a Java class Sequence that presents a similar interface to Stream, but with some changes. For convenience I copied the Javadoc comments from Stream, adapting them as necessary for my own code. I have included a copyright notice (namely Oracle) for the copied comments, but I'm unsure about the licence implications. Stream is released under GPL v2, which I understand requires that any derived work be similarly licensed. But does the GPL licence cover only the code proper, or does it also include comments? I would like to release my code under the MIT licence, but I'm unsure whether my inclusion of comments from Stream obliges me to release it under GPL v2 instead.
Comment: If you included comments from `Stream` when writing `Sequence`, is it reasonable to conclude that you studied `Stream` before and during the writing of `Sequence`?
Comment: Its documentation, yes, but not its code
Comment: The OpenJDK Stream.java implementation is GPLv2+classpath licensed. But the spec itself is not licensed that way, and there's nothing requiring that independent implementations of that spec be licensed that way. See the license notices if you're curious: https://docs.oracle.com/javase/8/docs/api/?java/util/stream/Stream.html
Answer:
But does the GPL licence cover only the code proper, or does it also include comments?

The GPL license is a copyright license and it applies to all parts of a project that are subject to copyright protection.
Copyright law provides copyright protection for things that are the result of a human creative process and that includes both source code, documentation and comments. There is an exception here in the form of the Merger doctrine, which states that if there is only one (or a very few limited) way to express an idea, then the expression is not copyright protected.

I would like to release my code under the MIT licence, but I'm unsure whether my inclusion of comments from Stream obliges me to release it under GPL v2 instead.

Unless those comments are the only way to write the needed information, copying those comments from Stream means that you have included GPLv2 content in your project and you need to use the GPL license yourself as well.
Answer: Missing any other statement, I expect the Javadoc comments from Stream to be under GPL as well.
One argument would be that of fair use. For example, if you included in your comment a relevant quote (e.g. from an standard). But I don't think it really fits this case.
Could you have different licenses for code and comments? I think you could, but the result is quite sketchy. Comments and code are clearly separated, so you could e.g. state that comments are available under CC-BY and code under GPL, I think there are some projects in that vein. The opposite is more peculiar. And, since code and comments will be on the same file (as opposed to having some GPL files with documentation and some different MIT files with code) it's more complicate to present to the final users.
I think you could release your whole project under GPL, with the provision that it can be used under a MIT license if they remove the comments from the code.
I would recommend to just write new comments from the ground up, though.
Comment: Thank you. That's a useful perspective.


how missiles or rockets change direction if gyroscopes prevent any direction change? they would bring back the rocket to same path?

Question: Gyroscopes are instrument which prevent any wobbling or direction change but then how rockets and missiles change their directions. To change direction we have to give signals to gyro or to the servo(which control flaps) directly.
Comment: I think you are confusing gyroscopic stabilization with gyroscope instruments used for navigation.
Comment: Please explain your reasoning. Are you thinking that the rocket is a gyroscope?
Comment: The question is closed and can't be answered, but "*Gyroscopes are instrument which prevent any wobbling or direction change*" aside from the confusion between sensor and effector gyroscopes, reaction wheels / [huge gyroscopes don't prevent turning](https://en.wikipedia.org/wiki/Gyro_monorail), they just respond to torque with [precession](https://en.wikipedia.org/wiki/Precession). Asking to reopen, as the question is very clear, it just includes two misconceptions that need to be explained.
Comment: For air-to-air missiles, check out https://en.wikipedia.org/wiki/Proportional_navigation The gyroscopes are generally in the missile seeker head, and sensors on them detect and measure the rate of change of the Line of Sight (LOS), and feed that to the flight control system to determine the collision course.
Answer: Gyroscopic rigidity in space means that a spinning gyroscope will stay aligned in the same direction while it is spinning. A rocket or missile is not a gyroscope.
Rockets and missiles may contain or use gyroscopic instruments as a method of navigation. That in no way means that the rocket or missile must stay aligned in the same direction as the gyroscope. The gyroscope is just a means to maintain a sense of direction.
For example, most aircraft have gyroscopic instruments. The pilot uses these to maintain awareness of Magnetic North even when experiencing compass errors. This in no way prevents nor assists the turning of the aircraft.
Answer: the gyroscope rotor in an attitude instrument is suspended by a gimbal assembly which allows the aircraft to pitch, yaw and roll without applying any torques to the spinning gyro, which swivels about freely as it "remembers" where the horizon is.
Those torques would cause the gyro to precess and thereby furnish wrong attitude information.
If the gyro rotor is rigidly coupled to the airframe, then as the airplane rolls, the gyro rotor rolls too and hence cannot tell you where the horizon is. As it does it will be producing a gyroscopic countertorque to the airframe, but for an attitude gyro this countertorque will be small.


What are the special rooms?

Question: Some rooms are specially marked with a purple question mark, and have unusual contents. I've found some minibosses, some bonuses, and some that don't have much gameplay effect. What all different types of special rooms are there, and what are their effects?
Answer: Not 100% that this is the entire full list, but I've seen:

Booyan the Clown: Challenges you to use either five axes or ten daggers to destroy a bunch of targets, gives a prize of a large chest if you do well, or else at least gold for every target hit.
Shrine: Pray at it to receive an item.
Paintings: Give details about previous games by the same developers. Sometimes, they turn out to be a Doomvas variant, and killing them creates a chest.
New Spell: Swap out your current spell for the new one sitting on a pedestal.
Jukebox: Lets you play any song in the game, but only while in that room.
Fountain: Restores a chunk of HP and MP.
Gambling Elf: You can pay him 25% of the money you have, in order to open one of the three chests behind him. Two are empty, one contains 3x what you paid.
Diary rooms: Read the diary to unlock another entry and learn a little bit more about what's going on.
Red teleporters: Teleport you to a random room. Changes each time you use it.
Miniboss: Kill a miniboss (sometimes one enemy, sometimes a pair of them), and they drop a large chest.
Comment: One thing to note about the painting rooms is that if you press up while standing below the painting, it gives you some history of the game pictured.
Comment: A note about painting/trivia rooms: They don't move when you approach, but you can test for hostility by attempting to read trivia by pressing up. If nothing happens, it's a Doomscape (upgraded Doomvas - shoots white balls).
Comment: The miniboss rooms are also special rooms.
Comment: Of course! Thanks, I've added them into the answer.
Comment: Also regarding painting rooms, you can press start and see if there is an enemy indicator to see if your painting is in fact a foe.
Comment: I'm pretty sure the jukebox music continues until you go somewhere that changes the music again (such as a different area of the map or a boss battle room).

What are the special rooms?


Installation of valitron with composer on windows 7

Question: I am trying to install valitron (https://github.com/vlucas/valitron) on Windows 8 but it doesn´t seems to work. It uses Composer (http://getcomposer.org) for installation, but documentation is quite poor.
Answer: open the php shell console,  than enter "cd path/to/your/htdocs/project". then you only have to enter the following: "php path/to/your/composer.phar require vlucas/valitron *". This should work, I have tested it with Xampp Local Server.


Are there any air navigation uses for the HF frequencies?

Question: I'm busy revising for a license conversion... Out of curiosity, does anyone know of a radio navigational aid that used the frequencies we call HF (2-25 MHz)?
Comment: What have you found so far? [Gee](https://en.wikipedia.org/wiki/Gee_%28navigation%29) and [LORAN](https://en.wikipedia.org/wiki/LORAN) come to mind.
Comment: Hadn't found anything - "UnrecognisedFalling Object" has set me right
Answer: Current airborne radionavigation systems use MF (NDB), VHF (VOR/LOC, marker beacons), UHF (G/S), and L-band microwave  (GPS/GNSS, DME) frequencies.  (MLS operates in the C-band, and airborne radar in the X-band, but those are niche applications.)
Historically, the only system that used HF was the UK Gee system.  LORAN-A had options for the use of HF frequencies, but these were never used, as MF operation just below the 2 MHz mark gave much more consistent results in both reception range and performance, and LORAN-C migrated into the LF band at 180kHz, partially to avoid the difficulties of being co-located with the amateur radio 160m band.  Decca also used LF frequencies, and the Omega system operated at VLF to provide (imprecise) global coverage.
Furthermore, the FCC frequency table shows no allocations for the Radionavigation service anywhere from 2 to 30MHz, in any ITU region.
Answer: Comm related - HF frequencies are used for transatlantic/transpac flights out of range of VHF/UHF Comm.


What was the morning star (Pulsar) called in Arabic *BEFORE* Quran was revealed?

Question: Surah aṭ-Ṭāriq speaks of piercing/morning star, commonly translated as Pulsar. My question is what was this morning star called before Quran was revealed? I mean, the star was always there, so Arabs must have used a word/name to refer to it. Was it Tariq? Thanks
Comment: The qur'an and any revelation before came in the language of the people it addresses. Else how should they understand the message of the revelation?
Answer: Tariq : from طارق.  طرق means sounding like a jackhammer  same as pulsar, discovered only recently and  ثاقب means piercing ! These 2 descriptions were made in the Quran inChapter 86 some1440 years ago. These descriptions could not have been from Muhammad himself but from The Creator of all the galaxies ! Another perpetual miracle of the Quran! God bless you all!
Dr Abdollah Gilani


Android: Custom region map

Question: I am trying to implement a map(not Google maps) like in the below image, which will have a hypothetical regions(not administrative) with different colors to indicate the population density. The regions will also be clickable and cliking on that will open a small info overlay.
For now I have the sliced images for each region with multiple colors (which color to be used is determined from an API request). But I am not exactly sure how can I implement this in Android? I've been doing some research for past couple of days but couldn't find anything satisfactory so far.
Things that I am having trouble to implement:

Put together all those images and form the map
How can I detect "tap/click" event in the regions
In one brief conversation with a guy, he mentioned something of "greyscale overlay-map, that is not visible to the user and which determines the right area by testing against the greyscale color index", frankly I didn't understand what he meant.

Here's what I am trying to achieve:

Any help or pointer to the right direction would be of great help.
Thanks for your time.
Answer: Check out www.trimaps.com, I think this is what you want. Sadly it isn't free.

Android: Custom region map


Why do we have "See more comments"

Question: I recently up-voted a savvy comment which implied that the OP should take a fresh look at his question. Then I noticed that there were more, currently hidden, comments. Only after I clicked to reveal these was it was apparent that the OP had already taken the savvy comment on board, and so there was no point in up-voting it. My question is: why not just show all the comments in the first place? You need to see them all to assess how to respond to them, in any case.
Comment: There are threads (in meta, mind you) with close to 100 comments (or more). Not hiding those chains would make it more difficult to read the thread. The same applies in main even though the length of a comment chains rarely exceeds 20. Comments are meant to be (by SE design) less important than answers. This is reflected here in the sense that showing answers has a higher priority than showing comments.
Comment: @JyrkiLahtonen: OK, it's reasonable to curtail the display of abnormally long chains of comments. But typically only a few comments are hidden, far fewer than the number showing. I don't think that this cutting the tails of the comments makes the reading easier. If the question or answer interests me, then I read the comments, which are often interesting too. I've never felt that comments are clutter. Also, occasionally scrolling is much quicker and easier than frequently locating and clicking on tabs.
Comment: John, I agree to an extent. This has annoyed me on occasion, too. But I have largely gotten used to it. I think that the reasons why it is coded the way it is are related to those listed in my first comment. That is just the impression I have. I could be wrong about this.
Answer: There has to be some limit on how many comments are shown. The site   shows $n$ most voted comments, not $n$ first or most recent, with the idea that the comments worth showing are those that make important observations about the post. This  design is also meant to suppress discussion threads consisting of  comments replying to other comments replying to other comments. If you need to see other comments to understand the meaning of a comment, that probably means the thread needs a clean-up (in your case, that savvy comment should have been deleted as obsolete).
Another benefit of limiting the number of comments is technical: it keeps the HTML source of the page  short  and focused on the actual question & answers. This helps search engines better "understand" what the page is   about, without being confused by tangential remarks. SE lives and dies by its Google page rank.
You can also read  Jeff Atwood's explanation at Comments: Top n Shown
(For the record, $n=5$ on main site and $n=15$ on meta sites.)

Why do we have "See more comments"


Why is inbuilt flash delay in manual mode nikon d5200?

Question: i have nikon d5200. In manual mode whenever i click a photo with flash, flash fires after 1sec. But it works fine in auto mode, there is no delay. can someone tell me why this delay is ?
Comment: You have made a statement. What are you asking? Also, what shutter speed is selected? Do you have second curtain sync enabled? If you have a shutter speed of around one second with second curtain sync enable then this is perfectly normal behavior.
Comment: @MichaelClark even if i shoot at 1/200 flash fires after some delay
Comment: What exposure mode are you using? What lens? What metering mode? What AF mode? What ISO? What other relevant settings are enabled or disabled?
Answer: Obviously it is a shutter delay, not a flash delay. The flash cannot fire one second after the shutter closes, but the flash does have to wait on the shutter to open.
You have at least four ways to cause a shutter delay.
D5200 menu D5 has a one second shutter Exposure Delay.
Selftimer is a shutter delay.
Redeye Reduction is about one second shutter delay while the flash fires about three times first.  This is in the sync menu (like with Rear Curtain sync delay).
The ML-L3 remote menu has a shutter delay mode.
You should get the free D5200 Reference Manual, at
http://support.nikonusa.com/app/answers/detail/a_id/13948/~/nikon-product-manuals-available-for-download
It has much more of this stuff in it than the "User Manual", and the PDF file is searchable.