How did "acker" come to mean friend in West Country English?

Question: Wiktionary

nickname from the Somerset slang for "friend" or "mate", e.g. Acker Bilk

Other dictionaries don't seem to even mention it, let along talk about its etymology.
How did "acker" come to mean friend in West Country English?
Comment: I wonder (so this is a comment rather than an answer) whether it's related in some way to [mucker](https://www.lexico.com/definition/mucker) (2nd definition as in "I had a pint with my old mucker Jim the other day"). This is said to be British army slang and particularly related to WW1 trench warfare where everyone was together in the "muck and bullets" but was, and to some extent still is, used by men who have no connection with the armed forces at all. I don't think I've ever heard a woman refer to a friend as a "mucker".
Answer: 'Acker' in the nineteenth century
Whether acker in the sense of "friend or mate" is Somerset-specific or not, the term probably arose within the past 100 years. William Holloway, A General Dictionary of Provincialisms (1840) has nothing for acker in the relevant sense, nor does James Halliwell, A Dictionary of Archaic and Provincial Words (1852) or Thomas Wright, Dictionary of Obsolete and Provincial English (1857) or James Jennings, The Dialect of the West of England, Particularly Somersetshire, second edition (1869) or Frederick Elsworthy, The West Somerset Word-Book (1886) or J. H. Blascke, A Few Steps to a Complete Dictionary of English Dialects (1890) or Joseph Wright, The English Dialect Dictionary (1898).
The absence of any visible nineteenth-century traces of acker as "friend or mate" puts a crimp in any theory that purports to derive it from an Old English predecessor.

'Acker' as an Oxford -er coinage
It seems at least as likely that acker is an instance of a not altogether uncommon use of the suffix -er to form what Michael Quinion, Ologies and Isms: Word Beginnings and Endings (2002) calls "Colloquial or humorous nouns and adjectives":

-er3 Also -ers. Colloquial or humorous nouns and adjectives. {Probably an extended use of -ER1 ["a common and productive suffix, with several senses"]}

Examples are footer (football), rugger (rugby), brekker (breakfast), and soccer (the last from an abbreviated and clipped form of Association Football). The style is to abbreviate (and often to distort—the root word, an then add -er. This was originally Rugby School slang, later adopted at Oxford University about 1875, then extended into general use. Most examples have since disappeared; only soccer has become standard English. A few are spelled -ers (Twickers for  the rugby ground at Twickenham), though most with this ending are adjectives: bonkers and crackers (mad), preggers (pregnant), starkers (stark naked).

Eric Partridge, A Dictionary of Slang and Unconventional English, eighth edition (1984) actually lists an instance of "ackers" that seem to follow this pattern—although in this case the term doesn't carry the meaning "friend or mate":

ackers. Activity at physical exercises: Pangbourne Nautical College: since ca. 1950 (Peppitt.) [Origin:] The 'OXFORD/R[OYAL] N[AVY] -ER(S)'.

Two additional instances, both from Australia, show up in Jonathon Green, Chambers Slang Dictionary (2008):

acca n.1 (also acker) {abbr. + pun on OCKER n. (4) [that is, "Australian English"]} {1970s+} (Aus.) 1 an academic, esp. one who trades on the proliferation of current, if ephemeral, intellectual fads. 2 quotidian, jargon-laden academic writing.

acca n.2 (also ack, acker) {abbr.} {1980s} (Aus.) acne.

So acker[s] has emerged as a slang term derived from activity (in England), from academic (in Australia), and from acne (in Australia).
If acker in the sense of "friend or mate" followed this same pattern, what word might it have come from? The choices aren't great, but a few aren't beyond the pale: accompanist, accomplice, acolyte, acquaintance. Be that as it may, I have not found any authority that traces acker to any of these words.

'Acker' in the wake of Mr. Acker Bilk
There is very little to go on in trying to trace the origin of acker in the sense of "friend or mate" before the emergence of "[Mr.] Acker Bilk and His Paramount Jazz Band," which began to receive frequent mentions in Google search results in 1960. A Billboard item from April 28, 1962, notes that part of Bilk's shtick was that he was something of a rube from jazz-inhospitable Somerset:

Next upon the British scene was Acker Bilk. Publicized as a rustic eccentric by Peter Leslie, his fame as a concert attraction preceded his disk success. This came in late 1960 and Bilk was in the British charts almost weekly last year. His biggest success is "Stranger on the Shore."

And an item in a 1959 issue of Jazz Music includes this note about a May 9, 1955, recording by "Master Acker Bilk's Paramount Jazz Band" with "Acker Bilk" on clarinet [combined snippets]:

Apparently, these four tracks were the first to be recorded by Acker Bilk under his own name and Esquire, the label that has done much to put more names on the road to fame saw it fit to release four exceptionally good numbers by this young man from Somerset. It is also fitting to note that here we have Master Acker Bilk (the custom later to call him Mister Acker Bilk) in all his glory.

The most noteworthy point here is that Bernard Stanley Bilk was evidently billing himself as "Acker Bilk" at least as early as 1955 (he was born in 1929). An unidentified article in Quadrant (1982) addresses the acker in "Acker Bilk" as part of its inquiry into the origin of the Australian slang term ocker [combined snippets]:

Several correspondents who knew ocker characters some decades ago observed that the description 'ocker' was used with little or nothing to do with a given or family name and simply means 'fellow' or 'mate' The term could well be one of many Australian words which came from British dialects and there is a body of evidence, some quite circumstantial, to support this. A glance at a few standard reference works yields a number of clues, any one of which might have been the trigger which gave us 'ocker'. In isolation they may not seem very convincing but a word does not have to be commonplace or have a particular modern meaning before it can take a place in the language. ...

Of considerable interest is an assertion by Acker Bilk, the British jazz musician, that 'acker' is a Somerset term for 'mate'. It is probably related to the above examples and, if so, its form would be a relatively recent development. The evidence in documentation is hardly definitive but we should be prepared to accept that this usage exists, at least in the English oral folk tradition. In support of this another informant from the same general area of England recalled a common childhood phrase 'good my acker', readily translatable into Australian as 'good on you mate'. Thus 'acker' appeals as quite a likely source and the form of the word approaches that of the Australian version. A retraction of the short open 'a' in some English speech or simple error in transmission would easily have made 'acker' sound like 'ocker' to Australian or other ears in some past time.

Conclusions
I have not been able to find an earlier reference to acker meaning "friend or mate" in Somerset or West Country slang than the 1982 Quadrant article. Presumably, the term truly is a dialect word for "friend" in Somerset. Simon Elmes, Talking for Britain: A Journey Through the Voices of a Nation (2006) says as much:

acker a friend. Somerset usage; the jazz musician Acker Bilk, born in Pensford, Somerset, took his professional name from this dialect word

But the lack of any recorded mention of acker in this sense before the rise of Acker Bilk is striking—and somewhat puzzling. The slang term may be older than Mr. Bilk, but if so it led a remarkably stealthy existence prior to his emergence as a musical celebrity. In any event, I see no reason to suppose that acker meaning "friend or mate" goes back much further than the middle of the twentieth century.
Answer: I actually asked a few people from Somerset and they had never heard it so it's not a well-known word.
Its etymology seems to be very complex and perplexing. I searched quite a few etymology dictionaries but didn't find its origin.
As user121863 says:

The etymology may be simply unknown or lost in time.

I'm not an expert but I'm going to speculate.
It's probably derived from Old English gemæcca (or maca), which means companion, mate, friend, equal etc. (mentioned by a linguist on Reddit in his comment).
Make and match are derived from the same word gemæcca.
Quoting from Etymonline:

Make (n.): "match, mate, companion" (now archaic or dialectal), from Old English gemaca "mate, equal; one of a pair, comrade; consort, husband, wife," from Proto-Germanic *gamakon- (source also of Old Saxon gimaco, Old High German gimahho, Old Norse maki), related to Old English gemæcc "well-matched, suitable," macian "to make"). Meaning "manner in which something is made, form, shape, design, construction" is from c. 1300. Slang phrase on the make "intent on profit or advancement" is from 1869.

Match (n.2): "one of a pair, an equal." Middle English macche, from Old English mæcca "companion, mate, one of a pair, wife, husband, one suited to another, an equal," from gemæcca, from Proto-Germanic *gamakon "fitting well together" (source also of Old Saxon gimaco "fellow, equal," Old High German gimah "comfort, ease," Middle High German gemach "comfortable, quiet," German gemach "easy, leisurely"), from PIE root *mag- "to knead, fashion, fit."
Meaning "person or thing that exactly corresponds to another" is from c. 1400. Middle English sense of "matching adversary, person able to contend with another" (c. 1300) led to sporting meaning "contest," which is attested from 1540s. Meaning "a matrimonial compact" is from 1570s.

There's also makker in Dutch.

From Middle Dutch macker, probably from *gemacke ("companion"). More at make, match. [Wikitionary]

It's clear that gemæcca and makker are closely related.
There's also Macker in German which was borrowed from Dutch makker.

Etymology of macker:
From German Low German Macker ("companion; guy"), first attested in 1771 and hence possibly borrowed from Dutch makker ("mate, fellow") (1557). Further origin uncertain, but likely related to Old Saxon gimaco ("companion"), Old English maca, ġemaca ("companion, mate, wife, one suited to another, idem"), Old Norse maki (whence Swedish make ("husband")), from Proto-Germanic *makkô, *gamakkô, *makô, *gamakô ("an equal; comrade"), from Proto-Indo-European *mag- ("to knead, work"). Compare also French mec, which is of uncertain origin, but probably from Dutch. [Wikitionary]

According to Wikipedia, macker is derived (or closely related) to Old English gemæcca.
So I'd guess English borrowed macker from German and it became widespread. Then later on it lost the m due to Apheresis and became acker with the same meaning (friend, companion).
(Mucker is also a common word that means friend in some parts of the UK, I guess it's also related but I don't have any information about that.)
(There seems to be a good explanation here but it's in Dutch and I don't know Dutch (translation might be incorrect)).
According to Macmillan Dictionary Blog:

Match itself is centuries older and has quite complex origins. It was derived partly from the Old English word gemæcca, which lost its ge- prefix through aphesis (apheresis). This is a process where the initial sound of a word is dropped, as in because → cos, it was → 'twas, and acute → cute.
Originally, match meant an equal, or a partner, a complement, one of a pair. Then gradually it developed a new sense, of a contest between two 'matched' parties or players. These are the kind of matches that take place at Wimbledon and other sporting events; they appear as sense 2 in Macmillan Dictionary. In US English the word game is more usual in this context.
Comment: The Dutch site above is much as you have presented – it is most .likely that "maker" (and various spellings) came from the North German *ghemacke* '"with the addition of the suffix  -er and the loss of "-ghe" as you suggested. A difficulty is that Bristol had little or no trade with the Netherlands and North Germany. Then there is (OED) the far more recent: 3. d. **mucker**. A close companion or friend; a person with whom one regularly socializes or teams up (cf. to muck in- phrasal verb). 1947   J. Bertram Shadow of War vii. v. 239  *What's the griff, mucker?*
Answer: In Ireland, mostly the North, people refer to a friend as 'Mucker' which comes from the Gaelic 'Mo Chara'- (mo kara) which means my friend. Acker might be a version of this brought to the west country with immigrant workers from Ireland.
Comment: It would help if you backed up your answer with some research.
Comment: What do you mean? The origin of the word is somewhat of a mystery and I'm offering a possible origin.
Answer: Paul Flynn is more right here even than he realises. It's likely not from immigrant workers but part of a vernacular core of Gaelic language that includes luv (as, in the West Country, my luvver), just as where I live (Pennine South Yorkshire). Luv is clearly Gaelic: Scottish Gaelic leibh, a contraction of le sibh, a composite pronoun & preposition meaning 'with you, together with you, on your side, in your favour, by you' — le is the preposition 'with, together with, in company with, on the same side with', and denotes feeling; sibh is the personal pronoun, 'ye, you'. [Gaelic bh is always pronounced 'v', of course.] It crops up everywhere and at any juncture, notably in ta luv ('thanks to yer'). This is Scottish Gaelic tapadh leibh, pronounced (capitalising the stressed syllables) 'TAH-puh LEH-eev', 'thanks to you' (formal). Ta luv is standard shortening over time to leave out the medial unstressed syllable.

How did “acker” come to mean friend in West Country English?


Does the Catholic Church consider not administering a feeding tube passive euthanasia?

Question: If a person was near death due to a severe head injury, but now only completely incapacitated (as in, unable to respond to stimuli; eyes open, but not tracking; not able to speak or swallow), is it OK to withhold giving that person a feeding tube?  Does it matter what the odds for improved health are? And, if it is not OK, how does anyone benefit from the person's continued survival?
Answer: Yes, in your example, it would be passive euthanasia.
Food and water are not extraordinary means of life support, so withholding those from someone is as immoral as starving or dehydrating any other person to death. However, there are situations where administering food and water may be difficult and actually hasten death, in which case it would be immoral.
From the 2009 Ethical and Religious Directives for Catholic Health Services p. 31:

A person may forgo extraordinary or disproportionate means of preserving life.  Disproportionate means are those that in the patient's judgment do not offer a reasonable hope of benefit or entail an excessive burden, or impose excessive expense on the family or the community.

In principle, there is an obligation to provide patients with food and water, including medically assisted nutrition and hydration for those who cannot take food orally. This obligation extends to patients in chronic and presumably irreversible conditions (e.g., the "persistent vegetative state") who can reasonably be expected to live indefinitely if given such care.40 Medically assisted nutrition and hydration become morally optional when they cannot reasonably be expected to prolong life or when they would be "excessively burdensome for the patient or [would] cause significant physical discomfort, for example resulting from complications in the use of the means employed."41 For instance, as a patient draws close to inevitable death from an underlying progressive and fatal condition, certain measures to provide nutrition and hydration may become excessively burdensome and therefore not obligatory in light of their very limited ability to prolong life or provide comfort.

For ordinary vs. extraordinary means of life support, see §6.7 of Health Care Ethics by Benedict Ashley, O.P.
Comment: You could add the example of Terri Schiavo who was in almost exactly this situation. I believe the Vatican tried to intercede.
Comment: @MattGutting Was Terri Schiavo a bit different because they _removed_ her feeding tube rather than refuse to give it to her. I met with a chaplain and a palliative care specialist yesterday, and I brought her up asking if this was the same case.  They told me that the "ethics have changed" since then, even within the Church!  I nearly lost it after that...
Comment: This is a great answer, I just wish the people who I had to give this info to were Catholic to being with.  For the first paragraph #57, it sounds like a person of sound mind could choose to forgo some treatment (although maybe not a feeding tube or tracheotomy), but if a person is incapacitated, can a legal guardian (such as a father) make that decision?
Comment: [Alfie Evans](https://en.wikipedia.org/wiki/Alfie_Evans_case) was just such a case, where the court decided in favour of the "health" service. Different jurisdictions have different processes, so I suspect that the question in comments should be directed to law.se (making clear which jurisdiction you're talking about).


Geometry nodes connection between values

Question:
Hello, I don't understand why connecting the random value output and any of the grey inputs on the right doesn't match. What do I need to add? Thanks!
Comment: The round inputs/outputs is "kind of" only one value, but the rhombus show that these are more values. That's why you cannot connect them.
Comment: What do you want the random value for?  GN 3.0 doesn't really have a way to generate a single random float.
Answer: The way this seems to normally be done is to drive the Random Value's ID socket with an integer.  This changes the Value output socket to output a single value:

One of the not-well-documented features of 3.0 Geometry Nodes is that some nodes output type depends on their inputs.  In this case, an 'ordinary' ID would lead to a field output (the diamond shape) but forcing an int into the ID socket changes the output type to a single float value.


Why is the right hand side of the Equation of Geodesic Deviation 0?

Question: I'm reading through several primers on GR and I keep seeing the same thing over and over again with no explanation: why is the right hand side of this equation zero:
$$\frac {D^2\xi^a}{Du^2}+R^{\alpha}_{\beta \gamma \delta}\dot x^{\beta}{\xi}^{\gamma}\dot x^{\delta}=0$$Is there some assumption of Newton's First Law in this equation?
Comment: Is there a reason you expect the right hand side to not be 0? The geodesic deviation of $\xi^a$ from "nearby geodesics" is given precisely by the Riemann tensor - which encodes all there is to know about the intrinsic curvature of the manifold, what extra term were you expecting? Note that any equation X=Y can be made to have "right hand side equal to 0" by moving the Y over to the left side: X-Y=0 so whether terms appear on the left or the right is pretty arbitrary...
Comment: @DonaldAirey there is no way to really answer your question without knowing what you *expected* to be on the right hand side. For example, given Pythagoras' theorem: $a^2+b^2=c^2$, one can write it as: $a^2+b^2-c^2=0$...and when presented with "why is the right hand side zero?", one doesn't know how to answer such a question except with "that's what the Pythagoras' theorem says". Similarly I can not shed more light into your confusion beyond "that's what the geodesic deviation equation is" without some more context from you.
Comment: @enumaris - Suppose the solar system follows a geodesic path around the center of a spiral galaxy.  If r = 15 kpc, at $t_0 = 0$, then at $t_1$ you would expect the radius to be 15 kpc without any additional forces (that is to say, a geodesic created by the galaxies energy/stress).  But what if the space between the solar system and the center of the galaxy was expanding during the interval between $t_0$ and $t_1$?
Answer: Indeed, Newton's first law is implicitly assumed throughout general relativity, which is why you don't get extra "spontaneous acceleration" terms. More precisely:

We define a geodesic to be a path through spacetime that parallel transports its velocity vector. In flat spacetime, this would correspond to a straight line. In curved spacetime it's a path that's locally straight.
We postulate that a free particle, with no forces acting on it, follows a geodesic.
Using this postulate, we derive that free particles obey the geodesic equation, the geodesic deviation equation, and so on.

As you said, the postulate is equivalent to Newton's first law. It's baked right in from the start.
That's not a bad thing; Newton's first law is so fundamental to physics that if we ever saw an apparent violation of it, we would attribute that violation to an unseen new force, rather than throw out the law.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/83832/discussion-on-answer-by-knzhou-why-is-the-right-hand-side-of-the-equation-of-geo).
Answer: $\let\a=\alpha \let\b=\beta \let\g=\gamma \let\d=\delta$
Would you like
$${D^2\xi^a \over Du^2} = {R^\a}_{\!\b\g\d}\,\dot x^\b \dot x^\g\xi^\d \tag{1}$$
better? Actually geodesic deviation is the first member of this equation.
Let's review its meaning. You have a geodesic, whose tangent vector is $\dot x$, parametrized by $u$. Then a second, infinitesimally near geodesic. The separation vector between these geodesics is $\xi^\a$. Eq. (1) says that the second covariant derivative of $\xi$ (its acceleration) is given by expression at right, i.e. it can be computed via Riemann tensor.
Eq. (1) is purely geometrical, no dynamics is involved or necessary. Dynamics comes into play only if you state the principle of geodesic (which is not an independent principle in GR) as the generalization of Newton's first principle. Then Eq. (1) informs us that if no other forces are acting, two particles will notwithstanding fall apart or come nearer because of the curvature of spacetime.
This phenomenon is also known in Newtonian physics: two bodies moving in a general external gravitational field (neglecting their mutual gravitational attraction) will change their distance in time because of tide force.
Comment: @magma I'm afraid that Donald's primers not even said him that ${R^\alpha}_{\beta\gamma\delta}=-{R^\alpha}_{\beta\delta\gamma}$
Comment: No, I don't like it any better.  It appears to me that all you've done is assumed Newton's First Law, then incorrectly moved part of the left hand side to the right hand side (I would have guessed the equation should be $\frac {D^2\xi^a}{Du^2}=-R^{\alpha}_{\beta \gamma \delta}\dot x^{\beta}{\xi}^{\gamma}\dot x^{\delta}$.  You simply baked Newton's First Law into the equation and then rode rough-shod over it because you're assuming that space is static (that is, flat space and curve spaced don't change with time).  That's a dangerous and unsupported assumption.
Comment: Fixed missing minus sign! :-)
Comment: Dear Donald, Elio's answer is perfectly fine and there is no need for your sharp comments. Contrary to what you think, the equation is valid under all conditions (expanding, contracting or  somersaulting spacetimes). Any non staticity is encoded in the Riemann tensor, which may be time varying. As a matter of fact this equation is used to measure the passing of a gravitational wave, for example with an idealized GW detector as beautifully described in MTW page 444-445. Oh...sorry if MTW is not in the list of "primers" that you are reading through.
Comment: @magma regarding https://physics.stackexchange.com/review/suggested-edits/233386 please do not add blank comments just to bypass the 6 character limit for suggested edits. It is there for a reason. If you can't fix 6 characters, just leave a comment and move on.
Comment: @Kyle Kanos Please stop editing my formula, or else edit eq. 8.43 of *Gravitation* too.
Comment: @magma - Oh, I get it, MTW, Misner, Throne, Wheeler.  Gravity.  So, yeah, that's the primer I'm talking about.  Equation 1.6.  Perhaps you'd care to point me to the part of the book I missed that explains the $0$ on the right hand side of that equation.  And, no, I don't like you moving the terms around any more than I liked the $0$ popping up in an equation without an explanation.


Is Tripundra mentioned in the Smritis?

Question: I would like to know about whether Tripundra is mentioned in any of the Smritis?
Does any Smriti talk about Tripundra?
Does any Smriti ask Brahmins to keep Tripundra?
Answer: It is mostly not mentioned in the Smritis but widely mentioned in Puranas and some Upanishads. But while searching I found that it is mentioned in the Sankhayana-grihya-sutra Adhyāya II, Khaṇḍa 10:

Every day in the evening and in the morning,

He establishes the fire (in its proper place), wipes (with his hand the ground) round (it), sprinkles (water) round (it), bends his right
knee,

41. (And puts fuel on the fire with the texts,) 'To Agni I have
brought a piece of wood, to the great Jātavedas; may he, Jātavedas,
give faith and insight to me. Svāhā!
'Firewood art thou; may we prosper. Fuel art thou; splendour art thou;
put splendour into me. Svāhā!
'Being inflamed make me prosperous in offspring and wealth. Svāhā!
Thine is this fuel, Agni; thereby thou shalt grow and gain vigour. And
may we grow and gain vigour. Svāhā!'

Having then sprinkled (water) round (the fire),

He approaches the fire with the verse, 'May Agni (vouchsafe) to me faith and insight, not-forgetting (what I have learned) and memory;
may this praiseful Jātavedas give blessing to us.'

[7[2]. He makes with ashes the tripuṇḍhra sign (the sign of three
strokes) which is set forth in the (treatise on the) Sauparṇavrata,
which is revealed, which agrees with the tradition handed down by the
ancients, with the five formulas 'The threefold age' (see above, I,
28, 9), one by one, on five (places), viz. the forehead, the heart,
the right shoulder and the left, and then on the back.]

He who approaches the fire after having sacrificed thus, studies of these Vedas, one, two, three, or all.

Since this scripture is a Dharma Shastra, so the answer is YES.
Comment: What is name of Dharma shastra
Comment: It is Shankhayana griha Sutras. Technically it is a Dharmashastra like Gautama Dharma Sutras etc. @PashamVishnuVardhanGoud
Answer: There is mention of importance of tripundra in Puranas. An example is given below.

The Lord said thus :-"O excellent-faced lady, a person who applies
Bhasman is on a par with my son Ganesa. What is repugnnant to them
should be eschewed. A householder who is devoid of Brahman (Vedic
knowledge) and who does not wear the caste mark Tripundra falls into
the depths of hell. All his holy rites of worship, charitable gifts
and holy ablutions are in vain like the Homa performed in the ashes."

Linga Purana II.18.60-62

Hence, in  the course of all holy rites, the learned men shall wear
the caste mark Tripundra.

Linga Purana II.18.63
I am not sure if Tripundra is a caste mark as claimed by the translator J.L> Shastri or sect mark of the Saivites.
Comment: I told to keep according to smriti . not Purana
Comment: How is it a Caste Mark sir
Comment: I just typed the translation by J. L. Shastri. I don't know the answer to your question.
Comment: Thanks for answer sir . let it be
Comment: Puranas are also smritis. Are you asking for quotes from Dharma Sastras? If yes, then I will delete my answer.
Answer:
56-61. Having thus procured the sacred ash and having taken it (in his
hands), the knower of the hymns should clean it with Om and should get
it hallowed with seven hymns. (He should apply it) to his head with (a
hymn addressed) to Īśāna. (He should apply it) to his face with (the
hymn) Tat Puruṣa. He should hallow the chest with the Aghora (hymn)
and, the private parts with the Vāma (hymn), the feet with the
Sadyojāta hymn, and the entire body with Om. Then he should dust the
entire body from the soles of his feet to his head (with sacred ash).
Then he should sip water, and should put on a white, washed garment.
Having sipped water again, he should do his rites fully. Then having
taken the sacred ash and cleaned it with (the utterance of) Om, he
should, recollecting (Śiva) the three-eyed one, the support of the
three qualities, the creator of the three (Vedas) and the mighty one,
with the hymn Namaḥ Śivāya, put the mark consisting of three lines
(Tripundra) on his forehead.

Padma Purana, Patala Khanda, Chapter 108

Those to whom god Siva is dear, those who are  devoted to Siva, and
those who revel in worshipping the feet  of Siva, and those who wear
the tripundra mark (three horizontal  parallel lines of ashes) on
their foreheads, are indeed prominent  Bhagavatas.

Narada Purana I.15.68
60b-63. He who applies Tripuṇḍra on the forehead (has the merit of) bathing in every holy river or lake in this world such as the rivers Gaṅgā etc.
He who applies Tripuṇḍra on the forehead has the merit of one by whom seventy million great Mantras beginning with the five-syllabled one and crores of Śiva Mantras causing salvation have been recited.

He who applies Tripuṇḍraka redeems a thousand predecessors and a thousand yet to be born in his family.
64. In this world, he will enjoy all pleasures, a long life and freedom from illness and at the close of his life he will die
peacefully. 65-69. He will then attain a splendid divine body
possessing the eight valuable Aiśvaryas (such as Aṇimā etc.), will
ride in a divine aerial chariot. He will be served by hundreds of
celestial damsels. He will enjoy pleasures in different worlds in
turns, in the regions of Vidyādharas, Siddhas, powerful and energetic
Gandharvas, and the worlds of Indra and other Guardians of the world.
He will enjoy in the cities of Prajāpatis and finally reach Brahmā's
region where he rejoices for a hundred Kalpas. He will then sport
about in the region of Viṣṇu for the duration of the life of three
hundred Brahmās. Thereafter he attains Śiva's world and enjoys himself
there for endless years. He gets merged into Śiva. He is not born
again.

~ Skanda Purana Braahma khanda, Brahmottara khanda, Ch 16
Answer: Srimad Devi Bhagwatam 11.12.:

1-20. Śrī Nārāyaṇa said :-- O Devarṣi Nārada! Hear now the great secret and the fruits of besmearing one's body with ashes, yieding all desires.
.
The study of the Vedas, Sacrifices, Charities, asceticisms, vows and fastings of that man, who does not use the Tripuṇḍra, all become fruitless. Without using Bhaṣma (ashes) if one wants liberation, then that desire is equivalent to live after taking poison. There is no doubt in this. The Creator has not made the forehead vertically high nor round; but he has made it slightly slanting and curved fit to have the Tripuṇḍra. Making thus the forehead, the Creator wants, as it were, to inform everyone that every one ought to use Tripuṇḍra marks; the curved lines also are made visible for this purpose. Still the igorant illiterate man does not put up the Tripuṇḍra. Unless the Brāhmaṇas use the curved Tripuṇḍras, their meditation won't be successful; they will not have liberation, knowledge, nor their asceticism would bear any fruit. . .

I hope this clarifies all the queries. Prd..

Is Tripundra mentioned in the Smritis?


Separate css for every web page

Question: I am developing a website in asp.net 4.0. While designing I have a question

Is it good to have separate css for every web page?

OR

Have all styles in one css?

Please tell  me what is the best solution?
Comment: The best solution is the middle road - have a generic css for all pages, but small different among pages can always exists.
Answer: It's best to keep all rules in one CSS file, since this file will be cached for all subsequent requests.
Unless you have a ton of CSS (ie. more than a few hundred kBs), this should not impact CSS engine performance, but it will significantly speed up loading of pages since requests won't have to be repeated for each page loaded, which will be your single greatest load time gain apart from your HTML page being generated.
EDIT: You should think about implementing compile-time (or on-demand) concatenation; that way you can have multiple CSS files that will be served as a single file to your clients.
Answer: It depends on the size of your code base.
Typically global rules should all be in one file, unless you are dealing with a massive code base where organizing them into separate files makes sense (but still included globally on every request).
Usually page specific CSS should be put in its own file and only included on pages that need it.
Generally speaking with large code bases, you would have a minifier and build process that concatenates all your global css into one file and includes that in production environment. This can be difficult to debug, so in development its better to keep them as separate files.
Answer: Aside from the caching and minimizing benefits outlined in other answers, consider that your CSS is essentially assigning a theme to your website or web application. If you think about how a theme works in your favorite media player or web browser, when you apply that theme, it generally affects the entire application, not just one part of it.
Therefore, if you think of your CSS as a theme, it then becomes easier for your designers to then change the look and feel of your site without ever having to touch a single line of HTML. Since a good design practice is to keep your HTML, JavaScript, and CSS completely separate, it makes it easier to make changes to one without having to worry about changes to the others. This reduces chances for bugs, since things that don't change remain stable.
What's more, your designers only have to make changes to 1 file in order to create a new theme, which makes their job easier. It makes your job easier because you don't have to go through and fix a bunch of broken HTML and JavaScript because CSS experts had to make changes to code that might not be their area of expertise.
A good example of this practice is Stack Exchange. Stack Overflow, Server Fault, Super User, and Stack Apps all run on the same Q&A engine, but each one has a slightly different theme. To create a completely new Q&A site, the frontend changes pretty much involve only CSS changes. This is how Stack Exchange can get away with having only 1 designer, Jin, who manages the designs of every single Q&A site on the network. What makes his job easier is the standardization and simplicity, and following the "don't repeat yourself" rule of thumb.
From looking at the browser source, you can see there is only 1 CSS file:
<code>    <link rel="stylesheet" type="text/css"
        href="http://cdn.sstatic.net/stackoverflow/all.css?v=52aab16f8140">
</code>
Answer: no, it is not good to keep seperate css for every web page. a professional never do this. but u can use two or three separate css for different browsers..
Comment: Hi shonosn, welcome to Stack Overflow. You can make your answer great by explaining *why* a professional never does this. Otherwise, you're just some random person on the Internet making a statement. ;)  Hope this helps, and welcome!

Separate css for every web page


Can I automate a process of checking SharePoint list column's property changes?

Question: I have 300 SharePoint 2010 lists. Occasionally users change Groups in the column "Assigned To". I have to check if those groups were changed and choose original group back. Is there any way (code free) to know if someone changed SharePoint Group in column "Assigned To"? (can use SP Designer)
Answer: If you using content types on library or list, put there column with back up info like Assigned TO backup and make it hidden.
Prepare workflow on item change.
In workflow compare column Assigned To with Assigned To backup.
Answer: Create a column called "Originally Assigned To" for each list and hide this from forms and views.
Create two workflows the first will be triggered when item is created and the second when modified.
workflow 1:
Update currentitem:Originally Assigned To (value of current item Assigned To)
workflow 2:
If currentitem:Originally Assigned To does not equal currentitem:Assigned To
Email (Who ever needs to pick these up)
Doing this as two separate workflows prevents the originally assigned to column being updated to the new value when the item is modified.


Pi 4; 8GB RAM: Having fimware and OS(openBSD) both on the SD card

Question: Yesterday I installed openBSD on my Pi 4 with 8GB RAM:

I first installed the [UEFI firmware][1] on the vfat formated, primary, and only partition of an SD Card
I created an openBSD 7.3 boot stick
I inserted both in my pi, connected a keyboard and a monitor
Everything booted fine and I installed openBSD onto the SD card, which was previously holding the mentioned UEFI firmware
I rebooted a few times (while having the USB stick inserted) and everything went fine

I assumed that I had a working setup. However, when I booted the Pi today, I only got a warning that some firmware is missing. I assume, that during the installation process I overwrote the firmware, which was installed on the SD card, with the OS.
An easy solution would be to use the SD card only for the firemware and install the OS on an USB drive. This however, would mean that I waste a huge SD card to only store some firmware and permanently need to connect an USB drive to my PI...
I would prefer to have both, the firmware and my OS, on the SD card. How can this be done?
EDIT: When I insert the USB stick I used for installation it works fine again... Nothing should have been written to this drive, despite the image used for installation. I real don't understand why it boots fine when the drive is inserted and does not if it's missing...
[1]: https://github.com/pftf/RPi4
Answer: So I just copied the linked firmware (which was still present on the bootable, first partition of the USB drive) to the bootable, first partition on the SD card, which previously only contained the efi/ folder, and this solved the problem.


Grant permission required for EXTERNAL_STORAGE in Android M?

Question: Will the Android permissions WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE trigger the new grant permission dialog of Android M?
Answer: I agree with Guillaume Perrot 's answer. I have met the similar question when I write the permission of READ_WRITE_EXTERNAL_STORAGE in AndroidManifest.xml
with no permissions showing up in the app by default , people need to switch the toggle button of storage in the app permissions.Then I modify my targetSdkVersion in build.gradle to less than 23(MNC) and other number related with sdkVersion, the app installed with the permissions on.
The other way is to write requestpermission function in the place that you need the permisson. The code is as follow:
 if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)==
    PackageManager.PERMISSION_GRANTED) {
    //do the things} else {
    requestPermissions(new String[] { Manifest.permission.WRITE_EXTERNAL_STORAGE },
      AnyNumber);

Because I have less than 15 reputation so I can't vote for the Guillaume Perrot 's answer.Just use this way to show my idea.
Comment: ```if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)==
PackageManager.PERMISSION_GRANTED)``` is fulfilled even if I revoke permission in the settings. Then the app fail...
Answer: I solved add this if check version for Android M
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                    requestPermissions(new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
            }

Answer: My answer is based on my tests on M Preview SDK version 2, using an emulator.
If you target MNC preview API level, WRITE_EXTERNAL_STORAGE is not granted by default and will be part of the new dynamic permission API.
You will see the storage permission as a toggle button in the new app permissions menu in device settings, and you can use Activity.requestPermissions to show the popup for that permission.
However if you target api level < MNC, it won't be classified as a dangerous permission, and thus will be granted without a way for the user to disable it (not showing up in permission settings), and you will not be able to compile code using Activity.requestPermissions anyway as the preview SDK enforces minSdkVersion="MNC" to use the new APIs.
This is a different behavior than location permissions: whatever the API level you target, the user will be able to turn location off in permission menu.
For the permission menu itself, the permission toggle state is ON by default if:

Target API level < MNC.
Target API level = MNC but you upgrade app on device from a previous install where target API level was less than MNC.

Otherwise you will see the toggle as OFF by default.
Hope it helps.
Comment: And the difference I observed between storage and location permissions is clearly undocumented... I have no idea if it's by design, a documentation bug or a platform bug.
Answer: According to Android docs you don't need to request permission about read and write external storage.
Edit: in the latest Android M release you need to ask for both read and write permissions
Comment: Where do you see that?
Answer: According to the docs:

Limited Permissions Granted at Install Time: When the user installs or updates the app, the system grants the app all permissions that the app requests that fall under PROTECTION_NORMAL.

So because READ_EXTERNAL_STORAGE is falling under PROTECTION_NORMAL , it won't trigger the dialog.
But because the level of WRITE_EXTERNAL_STORAGE is PROTECTION_DANGEROUS, it will fall under this behavior as described in docs:

User Grants Permissions at Run-Time: When the app requests a permission, the system shows a dialog to the user, then calls the app's callback function to notify it whether the permission was granted. If a user grants a permission, the app is given all permissions in that permission's functional area that were declared in the app manifest

Here is the sources for the protection level:
detailed list
Comment: I just chechek, in android m some permissions has been downgraded, so your answer is completely wrong
Comment: Android docs say for example that the internet permission is granted without problem but it's now dangerous, so there only two hypothesis: the docs is completely wrong or there is a change in Android m source code about the protection level.
Comment: I think that the docs is not completely clear about this. The only explicit thing is that "the system grants the app all permissions that the app requests that fall under PROTECTION_NORMAL."
Comment: First of all I said about the read Permmision that it is in normal level, so half is right for sure... Second, where you found data about the permmision level in M?
Comment: Google is your friend
Comment: `READ_EXTERNAL_STORAGE` isn't `normal`, it's [`dangerous`](http://developer.android.com/reference/android/Manifest.permission.html#READ_EXTERNAL_STORAGE).
Answer: Storage permission falls under dangerous protection level, So all the dangerous protection level permissions will not be granted at install time in Android M, if App target SDK is set to 23. They will be given at run time.
And yes these permissions can be revoked at run time also.
No permission dialog will not be triggered automatically, you need to do a request by using API such as requestPermissions() method to show that native dialog.
Please check the dangerous level permission list here


Additional OS on my Laptop

Question: I need to install a Linux OS (SuSE or RedHat) on my machine running Windows 7. What is the best way to have a dedicated physical partition or virtual partition?
Answer: Basically, if you want to run two different operating systems on the same system, you have two options to achieve this.

Dual Boot
Virtualisation

Dual boot
A dual boot is a system set-up where the available drive space is divided into multiple spaces with each having its own operating system. The system's boot loader, the piece of software that allows you to boot into your operating system, will have you make an option which operating system you want to boot. With this set-up, every operating system has its own piece of drive space.
This set-up will ask the least of your hardware but will not allow you to run both operating systems simultaneously, you can only boot one at a time.
Virtualisation
When you're virtualising hardware to install an operating system on a virtual machine, you're running that machine in a host operating system. Basically, Windows 7 is booted and runs software to emulate a machine on which Linux is installed. Although this allows you to run two or more simultaneous operating systems, it will ask more of your hardware than running one single operating system. Other than that, there are certain (hardware) limitations and compatibility issues you should consider when using virtualisation.
There are several virtualisation products out there, the most known being VMware (commercial) and VirtualBox (open-source).
Comment: My HW: HP Pavilion dv6 Notebook PC-Intel Core 2 Duo CPU P8800 @2.66GHZ 2.67 GHZ-- MEM 4.00GB-- 64-bit OS..Windows7 Home Premium. 130GB Free disk space
Comment: @Albouazizi Well it depends on what you are trying to achieve, what programs will you be running inside the guest os?
Answer: You need more than one partition. Usually, 3 partitions are fine:

One for swap, twice as big as your physical memory.
One for / (the system, binaries, config, libs, logs)
One for /home where all the userdata is.

I never experienced a drawback from virtual partitions, but somehow I prefer dedicated partitions.
Comment: I don't think this is the information the OP is looking for...
Comment: But what is he looking for?
Comment: Thank's to All for answering.. I remember one thing, i can't use dedicated partition bcoz i have only one partition for Windows7 and other small partition for Windows recovery.. so i will go for VM.. Any suggestion for a User friendly VM software you suggestion?
Comment: For a different question, you should open a different question, which has the right tags, attracts the right people, fits to the headline. You can put a link here to your new question and there to your old one, imho. However - recent partitioning software allows to resize existing partitions, so I don't see a real reason.
Comment: @BoodPhilia, @AlBouazizi Ah, I think now I understand. It's not about primary/extended partition, but about real installation, or installation to a virtual machine. The word `partition` brought me on the wrong path.
Answer: From a performance point of view, a physical installation is preferable to a virtual install. Other factors, such as certain hardware being unavailable to the VM will also impact your decision.
Generally, I use VMs for such things as testing certain things in a clean environment, or development, where a number of machines need to be available (multiple Asterisk installs and so on).
Comment: i have no choice to only use VM bcoz i found only windows7 partition and the other partition is for windows recovery.. so What VM you suggest? thank you again
Comment: If you do wish to install to the local drive, whatever distro you choose can resize the Windows parition to make room for itself.

On the point of VM, I would recommend VirtualBox from Sun/Oracle.

Additional OS on my Laptop


exposing dynamic schemas with graphql

Question: My application handles schema on the fly. Users can upload new domains or change the definitions of existing domains. For ex, say, I ship the product with a user schema like this :
user {
  fn, ln, age
}
Later user can change this definition to include new properties;
user {
  fn, ln, age,
  salary, address
}

or they can add an entirely new domain concept.
If I use GraphQL, is there a way to change the schema dynamically ?
Another question is;
Our schemas have conditions that make some parts of the schema relevant. For ex;
the user schema may have something like this:
user {
  fn, ln, age, gender
  foo (if gender == Male)
  bar (if gender == Female)
}

are there provisions in GraphQL to express these. I am ok to handle it in java code, but, then the schema look ups need to be routed to my code rather than referring to a static schema registry.
Answer: I had to solve the same kind of problem: I have a graphQL java server which can load plugins dynamically (each plugins come with its own schema definition).
You have to implement your own GraphQLSchemaProviderand override public GraphQLSchema getSchema(HttpServletRequest request). Then load / reload your schema according to refresh time / request condition (ie: user) / anything else...
For your second question, you can use Inline fragment http://graphql.org/learn/queries/#inline-fragments

exposing dynamic schemas with graphql


How can a view controller "embed" itself in a UINavigationController - espessially when contained in a container view controller

Question: Sorry for the long story -
I have some issues about the proper usage of a navigation controller hierarchy.
Every UIViewController has a property self.navigationController
But not every view controller is presented from a navigation controller -  therefor that property could be nil.
more so -
Some view controllers expect to be able to do:
[self.navigationController presentViewController:nextViewController];

but if it itself isn't contained in a navigation controller hierarchy, that expression would do nothing.
So intern the view controller could test if it was embedded in a navigation controller:
if (self.navigationController == nil)
{
  // create a UINavigationController with a root view controller - the next view controller
  UINavigationController *nav = [UINavigationController alloc] initWithRootViewController:nextViewController];
  [self presentViewController:nav];
}

but that might defeat the purpose - because if the presenting view controller isn't in a navigation controller - why would the next view controller necessarily need to be in a navigation controller. Why wouldnt't the current view controller just do:
[self presentViewController:nextViewController];

and skip the navigation controller creation?
On those exact lines - another issue that I am facing -
Some view controllers expect to be presented from a UINavigationController -
Because they set navigation items - toolbar items, titles etc. in the supplied navigation controller bars.
If for some reason their self.navigationController == nil - how can they "put themselves" inside a navigation controller in order to assure that they can access those expected elements???
About the container view controller inside a navigation controller issue:
If you look at the stock iOS music app - you can see what appears to be a UITabBarController embedded inside a UIViewNavigationController - each tab is a separate view controller - while each can "push" and "pop" view controllers themselves.
I need to achieve a similar effect (but with a different layout) so I created a container view controller with UITabBar view inside.
I then created a presentation container view inside that container view controller
This container was where each child view-controller's view was presented in. (those are the 'child view controllers' of the 'parent view controller') - this is a bit of tongue twister and I apologize for that.
Tab bar toggles - the parent view controller swaps the visible view controller in that container.
Now each view controller is very generic - they have no idea of their containment but expect to have a UINavigationController variable that is set (non-nil) in order to set titles - buttons - navigation items etc.
How can a generic black box view controller "present" itself (embed itself) in a navigation controller-
How can a container view controller set the navigationController property of a child view controller?
Answer: I have an app that has a place-holder (self.mainView) for viewControllers to be placed based on a tab selection. Some of them need a NavigationController, and others don't. You can always do a test if self.navigationController == nil and work accordingly.
Here is some sample code I use to show a viewController into that place holder that may help you.
if (self.currentController) {
    [self.currentController willMoveToParentViewController:nil];
    [[self.currentController view] removeFromSuperview];
    [self.currentController removeFromParentViewController];
    self.currentController = nil;
}

switch (tag) {
    case 0:
        self.currentController = [self.storyboard instantiateViewControllerWithIdentifier:@"AboutViewController"];
        break;

    case 1: {
        UINavigationController *controller = [[UINavigationController alloc] initWithRootViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"EventsViewController"]];
        self.currentController = controller;
    }
        break;
}

if (self.currentController) {
    [self addChildViewController:self.currentController];
    [self.mainView addSubview:self.currentController.view];
    [self.currentController didMoveToParentViewController:self];
    [self adjustMainView];
    [self.view layoutIfNeeded];
}


View email source in iOS Gmail app

Question: Is there a way to view the email source HTML in the iOS Gmail.app? Show original is available on desktop browsers. I haven't been able to find it on the app.
Comment: Welcome to Ask Different :) A lot of operations available in the Gmail Web app are not available in the Gmail iOS (mobile) app. This is mainly to provide a decent user experience on a small screen sized device and the depending on relevance of feature.
Comment: it used to work as described here https://apple.stackexchange.com/a/190198/46541, but need you to verify if it still works.
Answer: This isn't on the app. The app is optimised for better performance and compatibility. The only way to do it is to use show original on the web. And that can be done only on a computer because Google immediately moves to mobile mode when logging in from a phone.

View email source in iOS Gmail app


How fast do Iron Golems respawn?

Question: I am trying to create an Iron Golem trap as outlined in this wiki entry (Iron Golem), however they seem to be respawning very slowly. I have enough villagers to spawn at least one golem, what else determines their spawn rate?
Answer: The wiki states that they spawn near houses, and near 15 villages.
Increasing the number of villages will increase the maximum number of golems in your trap, so it will allow the game to try and make a spawn even if there is already a golem in the trap.
Houses are marked by doors, to adding more doors to the trap will increase the number of successful attempts to spawn.
You could also speed up the trap, so there are more spaces for golems to spawn.
Comment: That means, according to Ronan Forman, that the Iron Golems spawn rate is 1 per 350 seconds. They will only spawn, though, if they have the amount of space at the time.
Answer: Spawn rate is 1/7000th per tick (20 ticks/second).  They spawn very slowly.

How fast do Iron Golems respawn?


Refrigerator freezing on top up to 9 degrees warmer on lower shelves

Question: Side by side Frigidaire 6 months old.  Has done this before, but was working fine by the time the repairman showed up.  It is NOT overloaded.  It does usually run a degree or two different, but not 9 degrees.
Answer: It sounds like the evaporator coils are freezing up and the fan is unable to keep the air moving, it could be a faulty defrost timer, this is unacceptable for a new fridge.


On automorphism of some finite 2-group of class nilpotency two

Question: Let $G$ be a finite 2-group of nilpotency  class  two such that $\frac{G}{Z(G)}=\{Z(G), aZ(G), bZ(G), abZ(G)\}\simeq C_{2}\times C_{2}$. Then do there exist a non inner automorphism $\alpha$ of $G$ such that $\alpha(a)\neq a$, $\alpha(b)\neq b$ and $\alpha(ab)\neq ab$ ?
For example this is true for  $D_{8}$,  dihedral group of order 8, or $Q_{8}$, generalized quaternion group of order 8.
Comment: @DerekHolt: This is a follow-on from a comment I left to an [earlier question](http://math.stackexchange.com/questions/150632/on-automorphisms-group-of-some-finite-2-groups#comment346988_150632) of his (or, indeed, hers).
Comment: @user1729: I'd call Derek a pro.
Comment: The meaning of "acts trivial only on $Z(G)$" is really not clear. Why not write what you mean in mathematical language? Do you perhaps mean "Does there exists a non-inner automorphisms $\alpha$ of $G$ such that $\{g \in G \mid \alpha(g)=g \} = Z(G)$?"  ?
Comment: Instead of re-posting your question, you could [take it to the pro's](http://mathoverflow.net/questions/ask)?
Comment: For future reference: instead of posting a new version of your question, you should instead edit the old version to improve it based on the comments posted. I've merged the old version into this one, since it appears you are providing more information to address @DerekHolt's comment.
Comment: This is almost different  with earlier question.
Answer: Yes there does exist such an automorphism. Note that the conditions $\alpha(a) \ne a$, $\alpha(b) \ne b$, $\alpha(ab) \ne ab$ imply that $\alpha$ is non-inner, because an inner automorphism $c_g$ must fix every element of $gZ(G)$.
If $Z(G)$ is not cyclic, then it contains a Klein 4-group $\langle x,y \rangle$ and we can define $\alpha(a)=ax$, $\alpha(b)=by$, $\alpha(ab)=abxy$, $\alpha(g)=g$ for all $g \in Z(G)$.
So suppose $Z(G) = \langle x \rangle$ with $|x|=n$. If $n=2$ we have $G=D_8$ or $Q_8$, which you know how to do.
If $|a| = |b|=2$, we can define $\alpha(a)=b$, $\alpha(b)=a$, $\alpha(x)=x$, so suppose that $|a|>2$.
If $|a|<2n$, then by replacing $a$ by $ax^i$ for suitable $i$, we get $|a|=2$. So suppose $|a|=2n$ and hence $\langle a \rangle$ is a cyclic subgroup of $G$ of index 2.
2-groups of order at least 16 with a cyclic subgroup of index two are known to be abelian, dihedral, semidihedral, generalized quaternion or modular, and the only one of these with $|G:Z(G)|=4$ is the modular group with presentation $\langle a,b \mid a^{2n}=b^2=1, a^b = a^{n+1} \rangle$. For this group, we can define $\alpha(a) = ab$, $\alpha(b) = ba^n$.


How do I change my debit card details in Google Play?

Question: How do I change my ATM card details in Google play as my old card has been damaged and I cannot purchase anything from my Android phone?
Answer: As Dan has detailed in his answer you can change it via the Play Store on your phone or you can manage your payment methods via the Google Wallet site. This should allow you to remove your old/damaged card and add a new payment method.
Answer: When you get the small white dialog with the green Buy button, press the down-arrow in the top-right corner (next to the price). Then click on Payment options and Add credit or debit card.


Propane stove/oven soot/carbon smell

Question: I have a brand new oven/stove that runs on propane. Everytime I try to use the oven it ends up making the kitchen smell like that black soot carbon. I also can see inside the oven tall flames on either side of the bottom. I don't know if the flame is to come way up high like that. It is also orange yellow flames. My stove top flames have a yellow color as well and make the bottom of my pans all black and nasty with soot. Someone told me I have to have the flames adjusted but I don't know.
Answer: This sounds very likely a "gas" stove which has not had a propane conversion. Propane is run at a higher pressure than natural gas so all burner orifices must be down sized. Often stoves will come with a propane conversion kit included but sometimes you need to order one separately. Symptoms of a non-converted stove are large yellow flames. Correct flames should be blue with the tiniest tips yellow.
Everything where I am runs on propane- we do not have natural gas. Every gas (versus electric) appliance we install needs to have a propane conversion done to it. On a stove this entails changing the gas orifices in all cooktop burners, the oven burner, the broiler burner, and changing the orifice on the pressure regulator.
Do not use your stove until it is converted properly by someone who knows what they are doing (not a DIY thing). There is way too much flame and heat for how your appliance was designed. Serious possibility of a house fire.
Comment: Probably a house fire after being poisoned by CO gas.  This is a yesterday job, because tomorrow is too late.
Comment: Kyle got it right.  It probably wasn't converted to propane, which require smaller orifices to operate properly.  Not only that, propane has a higher energy content than natural gas which is another reason to downsize the orifices.   You want blue flames, not yellow.   Like Kyle and Crip said, this is **DANGEROUS** and shouldn't be used until converted.
Comment: The danger of CO leakage is MUCH greater than that of a house fire. It's essentially the equivalent of having an open camp fire in your living room.
Answer: If you are certain that the oven is set up for LPG (see the answer by Kyle), then another thing to check is that the air intake to the oven burner isn't blocked, for example by packaging materials that weren't removed when the oven was installed.
To get a good blue flame, you need a mixture of gas and air.  That means there's an air intake next to the gas nozzle.  If you ever used a Bunsen burner in school science, that's the holes at the base of the burner tube.
Answer: Both existing answers are accurate, but it's worth checking the regulator that's supplying the gas. It should be a fixed one giving the correct pressure for LPG, and may have a fault, making the whole thing even more dangerous. And at the same time, check the pipework for any leaks, too. Although that would make gas escape (dangerous) rather than suck air in. But with an outside leak, it may not be found easily.

Propane stove/oven soot/carbon smell


What is the number of roots of this equation?

Question: We are given ordered sets of positive integers A and B with n elements each and an integer C, how can we find the number of integer roots of the following equation:
$\sum_{i=1}^n floor(\frac{A_i*x}{B_i}) = C $
I have been stuck on this problem for such a long time. I have tried solving using all the properties of floor functions I know till now, it just doesn't fit into any.  An example will be when A = (1,5) and B = (2,4) and C = 3, the number of roots is 1, the root is 5. Any help will be very helpful to me, thanks.
Comment: Done :) Thanks for trying to help me out. I am new here.
Comment: Welcome to Math.SE Kindly share your thoughts on the question you put up so as to maximize the number of possible contributors.
Answer: If $x=x_0$ is a solution then so is any x in a small enough interval to the right or the left of $x_0$, so an equation of this form will not have discrete roots - its solution set will consist of one or more intervals (unless it is empty).
If all the rationals $A_i/B_i$ are positive then the sum of the floor functions is a sum of monotonically increasing functions so it is itself a monotonically increasing function of x. Its solution set is therefore either empty or it consists of a single interval. An example with an empty solution set is A=(1,1), B=(1,1), C=1 i.e.
$$2 floor(x) = 1$$
Similar argument holds if all $A_i/B_i$ are negative.
If $A_i/B_i$ are both positive and negative then the solution set can consist of an infinite number of intervals. For example, consider A=(-1,-1,2), B=(1,1,1), C=0 i.e.
$$2floor(-x) +floor(2x)=0$$
Comment: Modified the question, I needed number of integer roots and All A_i and B_i are positive, thank you for your answer :)


the location of javascript in the html?

Question: i am a new learner of javascript, from a book, i know there are three parts to put into javascript in html. one is in  .... two is under . the last is under. which is best? what's difference between them?
Comment: Under `body`? Not sure about that one.
Answer: Depends...
Advantage of having it appear before  is the loading of the scripts won't block the parsing of the page (because downloaded scripts are synchronous, because of possible document.write() etc), and you don't need to wait for DOM ready for descendants of the body element.
It is also recommended by Yahoo.
Keep in mind any scripts that modify the same element they are in will trigger Operation aborted in IE6 and 7.
In saying this, however, I place my scripts in head as it seems like a more semantically correct element to place them. It is also easier for maintenance, only having to check in one spot for scripts.
If the downloading of the JavaScript ever became an issue with my sites, however, I would have no issue with placing them before closing  tag.
Answer: YSlow recommends that you put JavaScript just before the  tag.  That way they don't block parallel downloads:
http://developer.yahoo.com/performance/rules.html#js_bottom
Answer: The current popular convention is to place scripts before the closing  tag.
In general, you may want to place a script in the head that will modify the html/css behavior, libraries such as modernizr, html5shiv, etc. are meant to supplant the behavior of CSS, so should be in the .  Those are the only scripts I would place in the head section of the document.
Designing your page/site so that scripting isn't needed (to as much of an extent as possible) is the best guideline you can have for a public facing site that may rely on search traffic.  If you are developing an intranet/extranet/saas application it isn't as important.  What will go along with this is placing scripts at the bottom before the closing body tag, so that all other downloads on the page occur first.
Beyond any of this, having your scripts limited (through minification, and merging) to 6 on a page will allow for scripts to be downloaded simultaneously on browsers that support that behavior.  There are tools/techniques that improve on this.  Some will bind to the window/load or document/ready events so can be placed anywhere.  Having your scripts, css and images on separate CDN domains can help (or spread across a few CDN domains).  Avoid having more than 4 total domains in use on a given page as much as possible (excluding common ones such as google analytics, which is likely to already be in the local DNS cache.
I would suggest reading "Even Faster Websites" by Steve Souders for more coverage on this area.  Optimizing performance is about more than just where to put your JS.
Answer: You should usually put JavaScript in the  section (unless certain conditions apply, which are explained below). Some people put it in the body to make quick and dirty changes to the document, but these days it's really not good practice.
Putting it in the head ensures that it loads when the document loads, and it's also easier to manage when it's all in one spot, rather than sprinkled around the page.
Some scripts that may request things from servers are put at the end of the body to prevent "hanging" the page load, but at this point you won't be doing that.
In short, it goes in the  section.
Comment: Wrap your html tags in backticks ;)
Comment: Can you mention advantages to having it in the `head`?
Comment: I guess it really depends on what you're doing. It's good to have it in the head mostly for readability and to have it ready to execute upon pageload. However, if it's going to hang the page load, then it's obviously a better choice to insert those at the bottom of the page.
Comment: Ah... Sorry... Didn't realize it wasn't coming through.

the location of javascript in the html?


Solve over integers $\frac{xy}{z} + \frac{yz}{x} + \frac{zx}{y} = 3$

Question: I am trying to solve $\frac{xy}{z} + \frac{yz}{x} + \frac{zx}{y} = 3$ over integers, but I have no idea what's the best way to do it. I have tried multiplying both sides by $xyz$ and then figuring out that $z$ divides $xy$, $x$ divides $yz$, etc, but with no effect.
Comment: Are you trying to find just 1 solution, because $x=y=z=1$ is a solution.
Comment: I'm trying to solve this equation so I'm looking for every triple $(x, y, z)$ satisfying this equation.
Answer: It appears there are no non-trivial (i.e. not $x,y,z = \pm 1$) solutions: sorry, no number theory to do here. (Just some analysis.) Dividing everything by $xyz$ puts the equation in a nice form:
$\frac{1}{x^2} + \frac{1}{y^2}+\frac{1}{z^2} = \frac{3}{xyz}$.
Staring at that for a moment, it seems like the LHS is always larger than the RHS, and this is easy to show. Suppose WLOG $x \leq y \leq z$.
Case 1: $x < z^{2/3}$. Then
$\frac{1}{x^2} + \frac{1}{y^2}+\frac{1}{z^2} \geq \frac{3}{z^2} >\frac{3}{x^3} \geq \frac{3}{xyz}.$
So there are no solutions with $x < z^{2/3}$.
Case 2: $x \geq z^{2/3}$. Then
$\frac{1}{x^2} + \frac{1}{y^2}+\frac{1}{z^2} \geq \frac{3}{z^2} > \frac{3}{z^{7/3}} \geq \frac{3}{xyz}$,
since the strict inequality $z^{-2} > z^{-7/3}$ holds for $z > 1.$ So there are no solutions in this case either.
Answer: Obviously $xyz\ne 0$.
Since $$3xyz = x^2y^2+y^2z^2+z^2x^2\geq 3\sqrt[3]{x^4y^4z^4}$$
we have $$xyz\geq (xyz)^2\Longrightarrow 0\leq xyz\leq 1$$
Now since $x,y,z\in \mathbb{Z}$ we have $xyz =1$. So $(1,-1,-1)$ and all permutation are solution as $(1,1,1)$ is.
Answer: If an odd number of the variables $x,y,z$ are negative, (i.e. if exactly 1 or all three are negative) then the LHS is clearly negative, so there can be no solution. If exactly two of them are negative, then we can exchange both their signs to get a solution with all of $x,y,z$ positive, and vice versa. So we can take $x,y,z$ all positive WLOG.
But in this case, by AM-GM we have
$$\frac{1}{3}\left(\frac{xy}{z}+\frac{yz}{x}+\frac{zx}{y}\right) \ge (xyz)^{1/3}$$
But the RHS is obviously $\ge 1$ if $x,y,z$ are positive integers. Therefore if the LHS equals $1$ (which is your equation), we must have equality throughout. Therefore $(1,1,1)$ is the only solution in positive integers, and by swapping signs we get $(1,-1,-1)$, $(-1,1,-1)$ and $(-1,-1,1)$ as the others.
Answer: your equation can factorized ot $$x^2y^2+x^2z^2+z^2x^2=3xyz$$
and then use $$(xy)^2+(xz)^2+(yz)^2\geq x^2yz+xy^2z+xyz^2$$ and we can write
$$3xyz\geq xyz(x+y+z)$$
can you proceed?


.NET ODBC Oracle Params getting param name returned by db provider- possible?

Question: I'm converting some RDO code to ODBC Provider code in .NET.
The problem is parameter names were not specified in the orignal code, but param values were retrieved by parameter name after the command was executed.
Is there anyway to have parameter names populated by the provider once the command is executed so calling code can access params by name.
Let me show you an example of the declaration of param and accessing of it.
<code>    With rdqryClntBasic
        .Parameters.Add(.CreateParameter) : .Parameters(0).Direction = ParameterDirection.Input
        .Parameters(0).DbType = DbType.String
        .Parameters(0).Value = sClntProdCd
</code>
End With
.EffectiveDate = ToDate(rdqryClntBasic.Parameters("dtEffDt").Value)
You can now see how this "used to work in RDO/VB".  For some reason it would accept this and know what the param names were after execution.  I imagine it had to do another round trip to the db to get this info.
Is there anyway to mimic this behaviour in .NET for ODBC Provider (using Oracle)?  Or am I stuck manually specifying the param names in the code (I understand this is the better option, but wondering what the alternative is to match the original code as closely as possible).
Answer: No, parameters in ODBC are positional not by name.


Entering UK two times in 12 months

Question: Basically I have got foreign car UK Driving License. Can I enter UK two times in 12 months. I mean like I enter country and I stay here for couple months and I leave  and come back again. Example - I have stayed here 4 months, then I have decided to leave and come back again and stay 6 months. Is it allowed to do like that with foreign car If I have got insurance and all documents from foreign country?
Answer: You may only use a foreign registered car in the UK for up to 6 months in any 12 month period so it depends how long you will be living outside the UK. https://www.gov.uk/importing-vehicles-into-the-uk/temporary-imports
Comment: Depending on how they count, and on how much time elapses between the visits, it might be okay.
Comment: @phoog good point, the question didn't specify how long they were going to be away. I'll edit the answer. Also, I have reason to believe enforcement is nonexistent.

Entering UK two times in 12 months


Solve $\int_{0}^{\infty}\frac{\ln(2x)}{4+x^2}dx$ by contour integration

Question: I'm a little stuck with this one. I've found the singularities to be at $\pm 2i$ and $0$ (branch point). So far, using a branch cut at $2\pi$ I've found that
$$\int_{0}^{\infty}\frac{\ln(2r)}{4+r^2}dr+\int_{0}^{\infty}\frac{\ln(2r)+2\pi i}{4+r^2}dr = 2I+\int_{0}^{\infty}\frac{2\pi i}{4+r^2}dr$$
And
$$\int_{0}^{\infty}\frac{2\pi i}{4+r^2}dr = \text{Res}(r=2i) \\ = -2\pi^2\lim_{r\to2i}\frac{r-2i}{(r-2i)(r+2i)} = \frac{i}{2}\pi^2$$
My problem is that the answer I found is completely imaginary, and I'm not sure how that's possible given that the original function is real. Any help is appreciated.
Comment: If you are integrating around a key-hole contour then the first and second integrals should cancel.
Comment: The original integral does not make sense (as a real integral) because $2x$ does not have a real logarithm when $x\le0$.  Should the integral be from $0$ to $\infty$?
Comment: You're right! I accidentally wrote down the integral wrong here, it's changed to the right bounds now
Comment: Not entirely sure what you mean here.  You say "the answer I found is completely imaginary", do you mean the answer $i\pi^2/2$?  As far as  I can tell from your working, that's the answer to a different integral and therefore no problem.
Comment: My problem is I don't know how to get the final answer from here, or whether this answer is correct.
Comment: If you still don't get @ZaidAlyafeai 's comment, he's probably hinting at the $$\int_0^\infty\frac{\ln(2r)+2\pi i}{4+r^2}\ dr$$which should probably be negative...
Comment: You have two approaches either integrate

$$f(z) = \frac{\log(2z)^2}{z^2+4}$$

around a key-hole contour or integrate

$$f(z) = \frac{\log(2z)}{z^2+4}$$

around a half-circle on the upper plain  were the branch-cut is chosen on the imaginary axis.
Comment: Why is $\log(2z)$ squared if I choose to integrate around a keyhole contour?
Answer: Consider
$$f(z) = \frac{\log(2z)}{z^2+4}$$
By using a key-hole integral with branch-cut on positive axis we should get
$$\int^\infty_0 \frac{\log(|2x|)}{x^2+4}\,dx + \int_{\infty}^{0} \frac{\log(|2x|)+2\pi i}{x^2+4}\,dx =2\pi i \sum \mathrm{Res}(f,z_0)$$
We see that the first and second integrals will cancel. Now to avoid that consider
$$f(z) = \frac{\log(2z)^2}{z^2+4}$$
By using a key-hole integral with branch-cut on positive axis we should get
$$\int^\infty_0 \frac{\log^2(|2x|)}{x^2+4}\,dx + \int^0_{\infty} \frac{(\log(|2x|)+2\pi i)^2}{x^2+4}\,dx =2\pi i \sum \mathrm{Res}(f,z_0)$$
$$\int^\infty_0 \frac{\log^2(|2x|)}{x^2+4}\,dx - \int_0^{\infty} \frac{(\log(|2x|)+2\pi i)^2}{x^2+4}\,dx =2\pi i \sum \mathrm{Res}(f,z_0)$$
Now you can see that $\log^2(2x)$ will be cancelled and we are left out with $\log(2x)$.

Another approach
Integrate around a big half-circle indented at 0 where the branch cut is chosen on the imaginary axis then for
$$f(z) = \frac{\log(2z)}{z^2+4}$$
we have only one pole at $z = 2i$
$$\int_{-\infty}^0 \frac{\log|2x|+\pi i}{x^2+4}\,dx +\int^{\infty}_0 \frac{\log|2x|}{x^2+4}\,dx = 2\pi i \,\mathrm{Res}(f,2i)$$
$$2\int^\infty_0 \frac{\log(2x)}{x^2+4}\,dx + \pi i\int^\infty_0\frac{1}{x^2+4}\,dx = 2\pi i \,\mathrm{Res}(f,2i) $$
Note that
$$\mathrm{Res}(f,2i) = \lim_{z \to 2i} (z-2i) \frac{\log(2z)}{(z-2i)(z+2i)} = \frac{\log(4i)}{4i} = \frac{\log(4)+(\pi i)/2}{4i}$$
$$2\int^\infty_0 \frac{\log(2x)}{x^2+4}\,dx + \pi i\int^\infty_0\frac{1}{x^2+4}\,dx = \pi \frac{\log(4)+(\pi i)/2}{2} $$
By comparison we have
$$\int^\infty_0 \frac{\log(2x)}{x^2+4}\,dx = \frac{\pi}{2} \log(2)$$
Answer:
METHODOLOGY $1$:  COMPLEX ANALYSIS

As already established in the answer left by @ZaidAlyafeai, the classical approach begins by analyzing the contour integral
$$I=\oint_C \frac{\log^2(2z)}{z^2+4}\,dz$$
where $C$ is the "keyhole" contour with the keyhole taken along the positive real axis.  In that case $0\le \arg(z)<2\pi$.  Then, we have
$$\begin{align}
\color{blue}{\int_0^\infty \frac{\log^2(2x)}{x^2+4}\,dx-\int_0^\infty\frac{(\log(2x)+i2\pi)^2}{x^2+4}\,dx}&=\color{red}{2\pi i \text{Res}\left(\frac{\log^2(2z)}{z^2+4}, z=\pm i2\right)}\\\\
&=\color{red}{2\pi i\left(\frac{\log^2(4i)}{4i}+\frac{\log^2(-4i)}{-4i}\right)}\\\\
&=\color{red}{\frac{\pi}{2}\left((\log(4)+i\pi/2)^2-(\log(4)+i3\pi/2)^2\right)}\\\\
\color{blue}{4\pi^2\int_0^\infty\frac{1}{x^2+4}\,dx-i4\pi\int_0^\infty\frac{\log(2x)}{x^2+4}\,dx}&=\color{red}{\frac{\pi}{2}\left(2\pi^2-i2\pi\log(4)\right)}\tag 1
\end{align}$$
where we find by setting real and imaginary parts of $(1)$ equal
$$\int_0^\infty \frac{1}{x^2+4}\,dx=\frac{\pi}{4}$$
and

$$\bbox[5px,border:2px solid #C0A000]{\int_0^\infty\frac{\log(2x)}{x^2+4}\,dx=\frac{\pi\log(2)}{2}} \tag 2$$

METHODOLOGY $2$:  REAL ANALYSIS
I thought it might be instructive to present an approach that relies on real analysis only.

To proceed, we begin by enforcing the substitution $x\to 4/x$.  Then, we have
$$\begin{align}
\int_0^\infty \frac{\log(2x)}{x^2+4}\,dx&=\int_0^\infty \frac{\log(8/x)}{(4/x)^2+4}\,\frac{4}{x^2}\,dx\\\\
&=4\log(2)\int_0^\infty\frac{1}{x^2+4}\,dx-\int_0^\infty \frac{\log(2x)}{x^2+4}\\\\
2\int_0^\infty \frac{\log(2x)}{x^2+4}\,dx&=4\log(2)\int_0^\infty\frac{1}{x^2+4}\,dx\\\\
\int_0^\infty \frac{\log(2x)}{x^2+4}\,dx&=2\log(2)\int_0^\infty\frac{1}{x^2+4}\,dx\\\\
&=\frac{\pi\log(2)}{2}
\end{align}$$
agreeing with the result in $(2)$ as expected!
Comment: @ZaidAlyafeai Thank you my friend!  And yours was a very well-written solution!  (+1) also. -Mark
Comment: Without doubt you are one of the best here on posting instructive, well-written and formatted answers. keep it up.
Comment: @ZaidAlyafeai Thank you Zaid!


How to implement shortcut commands to the "Share > Email" under contextual menu?

Question: How to implement shortcut commands to the "Share > Email" under contextual menu in Mountain Lion?
Answer: The New Email With Selection service is basically the same, but it's available in more applications and views.
Comment: Thanks. I tried it and it only works if you highlight the file as text selection, not as file selection. So it grabs the text of the file into Apple Mail instead as a whole file attachment. That's lame or it could be a bug. Well, Mountain Lion is still in its first release, I hope Apple fixes that one on the next 10.8.1 release.
Answer: You can make a service for that using Automator. The following screenshots show you what to do:

Pay attention "Service receives" part.
Than save a service and activate it as in the post above. This will go into "Services" (not to "Share") though.


Consequences of .ssh/authorized_keys being world-readable

Question: OpenSSH sshd enforces mode 0600 for authorized_keys when StrictMode is enabled. How is mode 0644 more vulnerable?
Answer: The sshd_config man page says

StrictModes
Specifies  whether  sshd(8)  should  check  file modes and ownership of the user's files and home directory before accepting login.  This is normally  desirable  because  novices  sometimes  accidentally  leave  their  directory  or  files world-writable.  The default is yes.  Note that this does not apply to  ChrootDirectory, whose permissions and ownership are checked unconditionally.

I believe this refers not to ~/.ssh/authorized_keys but rather to ~/.ssh itself, which typically contains your private keys. With ~/.ssh set to mode 0700 (drwx------), nothing inside it can be accessed by other users (except root). This happens to mean authorized_keys itself cannot be world-readable (unless you use the AuthorizedKeysFile config item to specify another location).
The risks to a publicly-visible ~/.ssh/authorized_keys file are pretty minimal but do exist: if you have compromised keys (the attacker has access to them) or keys that are weak (e.g. low bit size or old cryptosystem), an attacker might be able to replicate or use those keys and this file might tell them which system(s) to try them on.
Consider CVE-2008-0166, a bug in Debian's OpenSSL build's random number generator. Debian had to create the openssh-blacklist package as a short-term solution to ensure the weak keys could be weeded out.
Answer: One of the principles of information security is to restrict permissions and privileges as much as possible.  Under this principle, only the minimum necessary permissions and privileges are granted to users, files, processes, etc.  StrictMode applies this principle.
The reason for this principle is to reduce the chances of giving an attacker something that could be useful to him/her.  In this case, an attacker that has read access to authorized_keys would be able see other hosts are able to connect to this host.  Knowing this information, the attacker could then look for ways to breach one of these other hosts, in order to gain access to this host.  The philosophy here is - why give the attacker something that he/she may be able to use, when there is nothing to be gained by doing so?


What's the difference between in 10 years and for 10 years?

Question:

We haven't spoken in ten years.
We haven't spoken for ten years.

What's the difference between the two in meaning?
Answer: You have an interesting example!  In your example the meaning of the two are equivalent, but that's not usually the case.
Normally
When we say in 10 years we mean that something will happen in the future (the time that will elapse before the event).
When we say for 10 years we mean that a situation has been happening (or will be happening with a future verb) over a period of 10 years (duration of time)
In your example
Your first option "We haven't spoken in 10 years" is using in to refer to a period of time during which the situation has continued.  This is because the verb is in the past and refers to an ongoing situation (not speaking) and then in gives the amount of time that has elapsed since that situation first started.  So because the event is the star of an ongoing situation in this case the effective meaning is the same.
Answer:
We haven't spoken in ten years
we haven't spoken for ten years

The question has been asked on different sites.Nobody could differentiate between the two sentences.
I think both have the same meaning and are grammatically correct.


Materials science and materials engineering

Question: Good day,
I would like to enquirer the followings:

What is the difference between studying materials science and materials engineering?
Are there any jobs exclusive to those who have studied materials science/ materials engineering
Answer: I frame my answers based on the materials tetrahedron modified as published in the 1990 Research Council Report in the US.
Materials science defines relationships between nature (chemistry and structure) and properties (mechanical, environmental, thermal, electrical, optical, magnetic) or between preparation (synthesis and processing) and nature. Materials engineering applies relationships between properties and performance (succeed/fail or min/max criteria) or between preparation and properties.
Here are two slides from my lectures for a course on the nature of materials (graduate level) to illustrate these statements.

The questions addressed in the disciplines are based on why something is the way it is (science) or how something can be used for an application (engineering). In a cynical view of the second slide above, one might say that materials scientists care nothing about where their material will be used (performance), they only care what is in it (nature), how it is made (preparation), and how it responds to a stimulus of some kind (properties). On the other hand, materials engineers care nothing about what the material really is at a fundamental level (nature), they only care whether making it (preparation) will give it the right responses (properties) so they can use it successfully in their application (performance). Unfortunately, some might say this cynical view has some level of truth, for example as shown by the cavalier attitude of some materials scientists about whether their materials have any real world applications at all or by the cavalier attitude of materials engineers to seek the fundamental reasons why their materials keep failing in use.
The predominant view for jobs in industry in the US is derived from the perspective of materials engineering. Materials science is based more in academia or research labs. Studies classed as materials science also appear in chemistry and physics departments. In my view in the US over the last decade or so, more jobs exist classed solely as materials engineering than those that exist classed solely as materials science.
Tangent to this, the predominate approach presented in the plethora of undergraduate textbooks on materials science/engineering starts from the perspective of materials engineers / metallurgists. Metals are the poster child of this group, followed by discussions of ceramics, a section in a chapter on semiconductors, and a chapter on polymers. Witness also the imbalance to metals engineering by specific examples of the snub to fundamental materials science in such textbooks by the lack of fundamental discussions about: the role of secondary bonds to define melting points of polymers, the role of HOMO/LUMO covalent bonding in molecules to explain band structures in semiconductors, or insights about dopant concentrations given in ppX scales translated to number density levels so as to calculate electrical conductivity. Finally, look also to this by the examples that present full chapters focused entirely on the various classes of engineering metals, various ways to process steel, various types of corrosion of steel in application systems, or TtT phase diagrams for steel.
Answer: From a different point of view : Engineers get jobs in industry because they can solve practical problems. Scientists get jobs teaching and doing esoteric research. My first boss had a degree of "metallurgy" ( from MIT) , so a scientist. I had a degree of "metallurgical engineer". He did not know how stuff worked such as the general differences between DC and AC electric. As an engineer ,I had 2 classes in electrical engineering, as a scientist he had none. He knew about about various metals being soluble in each other ; He did not know you could apply this principle and improve the ductility of some metals with a solution anneal ( dissolving brittle intermetallic compounds). He did do some clever stuff like distilling zinc from scrap ; he got the idea then hired an engineering firm to design and build the furnace.


Launching a popup via in octobercms backend via javascript

Question: Im trying to figure out how to launch a popup window with a relation widget in the backend using the Ajax framework for Octobercms.
The anchor provides a data-control='popup' option for creating a backend popups. The framework uses a jQuery method to call the backend $.request('onMethodName', { data: {id: id} });.
I've tried to add additional options for example $.request('onMethodname', { data: {id: tempMarker.id,control: 'popup' },control: 'popup',dataControl: 'popup' });
But with no luck. The documentation doesn't say how to do it either. I'm attaching this to a click event for a map marker (img tag) in the backend, a popup should appear to edit the marker data.
Answer: This was simple as replacing the $.request('onSomething') with $.popup(handler: 'onSomething')
Found this thanks to https://octobertricks.com/tricks/update-records-from-list-view-in-a-popup


what are the ways to avoid skidding off the runway apart from thrust reversers?

Question: what are the different ways to avoid skidding off the runway apart from thrust reversers?
Do crew have any option if thrust reversers are not available and the ground is too slippery which is making the vessel skids off the runways sideways?
Comment: Thrust reversers are often the *reason* why an aircraft went off the runway.
Comment: Why do you assume thrust reversers aid directional control?
Answer: Your question appears to assume that thrust reversers are an acceptable way of keeping an aircraft from sliding off a slippery runway. While this may be true in rare cases, generally speaking you would NOT want to use reverse thrust to avoid skidding off a runway as that typically would exacerbate the problem.
Consider the following scenario: you have an icy runway and a strong crosswind from the right. As you start the takeoff roll, the airplane begins drifting left. You apply right rudder to correct, and the aircraft heading moves to the right of the runway direction. If you resolve the engines thrust vector into it's components relative to the runway centerline, you have most of the thrust propelling you down the runway, a much lesser amount propelling you toward the right side of the runway.
Lets say the left drift continues in spite of the engine thrust vector driving the aircraft to the right side of the runway, and you decide to abort the takeoff using reverse thrust. Thus, the thrust vector relative to the runway centerline will slow the aircraft. However the thrust vector 90° to the runway centerline will be toward the left side of the runway, which when added to your leftward drift will likely put you off the left side of the runway.
If you Google "tower air 747 crash" you'll see a number of entries concerning just such a scenario and the result. I found http://flightsafety.org/ap/ap_mar97.pdf to be the most instructive, although I do not wholly agree with the conclusions or with the narrative of what happened (a friend of mine was in the jumpseat right behind the captain, and I flew as a f.o. with that captain).
An obvious answer to your question is to never get yourself into such a serious situation. Can you wait for better conditions? Is another runway available? But if you MUST use a slippery runway for either takeoff or landing (or have already foolishly committed yourself), remember that if a runway is that slippery, it's feasible to continue down the runway in a manner that your course (the runway direction) doesn't match your heading. If the captain of the Tower Air flight had elected to do that, he might not have had the accident he did, or he might have had a much more serious accident. Tough call!
Answer: The aerodynamic controls (ailerons, elevators and mainly the rudder for this question) still have an effect when the aircraft is on the ground but is still at speed. So even if the plane slides or aquaplanes a little bit at high speed it is generally controllable.
The problem is at lower speeds when these controls don't work as well / at all. You could be in a situation where the aerodynamic controls don't work and you are going to fast for the wheels to grip, or even you are stopped and a crosswind blows you sideways off the runway.
If the wind is down the runway hopefully you can get down, but taxying might be another matter. Possibly there are reduced cross wind limits on icy runways... I don't know I only fly light aircraft and generally not in those conditions.
Answer: Thrust reversers are not used to steer an aircraft.
On the ground the rudder is used to steer during landing and takeoff. The main wheel brakes can be used to make tight turns when taxing.


When does a verb not need an object?

Question: When do you just say "He plays" instead of 'He plays computer games", "He plays tennis"?
Comment: Your 2nd and 3rd examples have objects in them, not subject (predicative) complements.
Comment: Where is a subject complement in "he plays"? I'm afraid I don't undersand the question.
Comment: Any sentence should be written only when the writer wishes to convey the meaning the sentence expresses.
Answer: When you want to express the general action as a whole and expressing detail is unimportant or undesired, you don't use an object.

Person1: "What a cute baby!  Is he fussy?"
Mother: "No not at all!  He plays, he eats, and he sleeps!"

Another example (It speaks!):

Scientist #1: "Let me show you my new invention."
Scientist #2: "Ok."
Scientist #1 pushes a button.  The machine emits some warbling sounds: "wrrbl wrrbl hmm grrr... bbuble..smthing...who?...how?...bababa..baby.."
Scientist #2: "It speaks!"  <--------- (As opposed to, "It speaks English!")
Scientist #1: "Yes, it does."
Answer: As you already mentioned, this kind of construction most often occurs with intransitive verbs. For example:

He is dining.
She is sleeping.

"To dine" and "to sleep" are both intransitive, so a subject and verb are enough to create a grammatical sentence.
This can also happen with transitive verbs, but usually when referring to non-specific activity.

The child is playing.

Because of what we know about children, we assume the child is playing with toys, playing in the playground, etc., but we don't know the details. Subject-verb is enough here.

The musician is playing.

Because of what we know about musicians, we assume the musician is playing an instrument. We don't know if she's practicing by herself or giving a recital.
But because these examples are transitive verbs, we can be as vague or as specific as we like.

The child is playing football.

Now we know what the child is playing, but we don't know if he's playing with friends or with a team.
So subject-verb sentences are either due to intransitive verbs, or non-specific uses of transitive verbs.

When does a verb not need an object?


What is measure of angle $x$

Question: In the figure, $ABCDE$ is e regular pentagon and $FBC$ is a equaliteral triangle. What is measure of angle $x$
I didnt now how to find. Please help me. Thanku very much
Comment: Hint: $\triangle BFA$ is isosceles.
Answer: Since we know that  FBC is an equilateral triangle, we can deduce that  FBA is an isosceles triangle.
This plus the facts, that every interior angle in a regular pentagon measures 108° and every interior angle in a equilateral triangle measures 60° gives us the final result:
x = 66°

Comment: How find x=66, please told me, in detail form
Comment: Which is the asnwers correct, x=66 or x=84
Comment: ∠CBF = 60° and ∠CBA = 108° so ∠FBA has to be 48°.  Because the triangle FBA is an isosceles triangle we can deduce that BAF = \frac12 (180° - 48°) = 66°
Answer: Since two different answers are posted, I will chime in:
$$\angle ABC = 108^\circ$$
$$\angle FBC = 60^\circ$$
$$\implies \angle FBA = 48^\circ$$
$$\angle BFA + \angle BAF =   180^\circ- 48^\circ = 132^\circ$$
And since $\triangle FBA$ is isosceles,
$$\angle BFA + \angle BAF =\frac{132^\circ}{2}= 66^\circ$$
Comment: Thanky very much sir. Now i understand
Answer: IFF (If and only if) these conditions are met
All Sides are the same size
therefore the equal angles to each angle in the regular rectangle are as follows:  (excluding the equilateral triangle)
360/5 = 72*

Add the variable y and make it
(Y is the angle that is the shortest in that triangle on the bottom right side of the regular pentagon)
72 - 60 = 12

now we know the new Variable Y, lets also conclude the second triangle is an iso-metric triangle.  Meaning 2 of its sides are equal.  Therefore:
180 - 12 = 2x

Since there are 2 same angles with the third angle known as 16* All we got to do now is solve for X:
180 - 12 = 168
168 = 2x

168/2 = 2x/2
x = 84

So X is 84 Degrees

What is measure of angle $x$


Clustered index insert performance on not-so-unique column?

Question: In your experience, at about how many records does insert performance become intolerable when using a clustered index on not-typically-unique columns?
A good example I can think of would be the comments table for stack overflow. Do you think that insert performance would be acceptable if the comments table had a clustered index on their foreign key to the answers or questions table? I'm assuming that this would result in the fastest read performance for the way that comments are typically queried.
I often read that the clustered index should be reserved for uniquely-valued columns, but what if the table in question was most often queried by this index?
Answer: It Depends on:

The size of the rows
On Fill Factor (i.e. space left in the index)
The number of non-clustered indexes on the table
How often the index is reorganised (note: not so important when the clustered index is on a montonically increasing key)

You should benchmark for your particular situation.
Comment: don't forgot:
server CPU, Memory and Disk
Answer: You should always try to keep your clustered indexes unique. For tables that have a ton of inserts something like a int identity is a good choice cause the page being inserted on will often be in memory reducing disk access.
If you do not make your clustered index unique, SQL server will do it for you, cause it still needs to be able to somehow find particular rows. Maintaining the uniquifier will cost something.
So what if you want the clustered index on a comments table to be the post id. This can be useful cause looking up all the comments for a post becomes really fast, all the information is in the same area on disk.
No problems, make the index unique by adding more columns to it: Eg:
<code>create unique clustered index pk_comment(post_id, comment_id)
</code>
But... having this index means that your index is no longer monotonically increasing which may effect insert performance. It could also affect the amount of page splitting.
So, my recommendation would be to keep it simple and just chuck a primary key on comment_id, then profile the application add in covered indexes as required. Only if the underlying way the data is layed out on disk becomes a problem, you should consider complicating stuff.


How to disable context menu shadow in KDE 4?

Question: I don't like context menu shadows in KDE 4. Is there any way to disable those?
Answer: I've looked all through the settings, and, sadly, couldn't find a way. Context menu shadows are not connected to window shadows...
But you may completely disable compositing/special effects (Desktop Effects – KDE Control Module → Activation) and that will get rid of all the shadows... and lots of other eye-candy.
Answer: Run kcmshell4 style (also available somewhere from the menu in the System Settings application) and select a style to customise. QtCurve has many settings related to shadows.