Why isn't wind speed considered when calculating a heat index?

Question: I work outside in Florida, and the heat is sometimes unbearable. But if a breeze hits me, it makes it much more tolerable. There are some days where there is high heat and humidity, and a steady wind. Those days are much less uncomfortable than similar days with no wind. If we are trying to determine the apparent temperature, shouldn't wind speed be included in that calculation?
Answer: All weather agencies record 'ambient temperature'— how warm the air is in the shade and sheltered from the wind. This is done by placing weather recording instruments in a Stevenson Screen. The height above ground that Stevenson Screens are placed is between 1.25 and 2 m (4 ft 1 in and 6 ft 7 in). By using this approach weather readings from around the world can be regarded being consistent and relatable.
When weather forecasters produce a temperature forecast they try to produce a number that will be similar to what would be recorded by instruments in a Stevenson Screen.
Knowing the effect humidity and wind has on how humans feel temperature most weather agencies also try to forecast the apparent temperature. In colder parts of the world, agencies issue the forecast temperature and the wind chill factor. This isn't generally done for warmer regions, partly because predicting wind speeds and wind consistency can be difficult.
What is apparent temperature and how do they measure what it really 'feels like' outside?

Edit 14 September 2021
Apparent temperature forecast for the US and Louisiana, by NOAA

Apparent temperature forecasts for Taiwan.
Comment: The wind chill table was not created based on the "predictability" of wind properties.
Comment: you can find the weather forecast and the apparent temperature for any place on our planet at the norwegian meteorological institutes web site https://www.yr.no/en it is free and is aproved by UNICEF https://www.met.no/en/archive/weather-data-from-met-norway-approved-as-digital-public-goods
Answer: Apparent temperatures help delineate thermal stress, or how hazardous to human health that thermal condition actually is. Which is why high ambient temperatures are often accompanied with a "wet-bulb temperature" (aka misery index). This better defines how hazardous the high temperature is to humans. On the low end, wind chill temperature does the same thing but for cold temperatures.
Since thermal comfort is entirely subjective, it's not a measurable property that might carry any meaning.
Answer: The question is how one would define a heat index, and one could do that in many different ways that would all make sense:

The way the heat index is defined is for people sitting in the shade where they are not exposed to wind. That's a reasonable approach as it is not an uncommon situation for people to be in such situations.

One could define the heat index by taking wind into account. That too, would be a reasonable definition, but people are not all that often in places that have (i) shade, (ii) are exposed to ambient wind at the same time: If you're in a house or forest, you're generally not exposed to the ambient wind -- there might be a breeze, but its strength will very much depend on where exactly you currently are. If you're out where the wind will hit you, you're more likely than not also in the sun.

In other words, defining a "heat index" involves making some subjective choices about what you think matters to the people who are interested in knowing what tomorrow's heat index will actually be.
Comment: Sorry not buying... we have a wind chill doing exactly that in the winter.
Comment: Because when people are outside in the winter, they typically *are* exposed to the wind.


Functioning of BRCA2

Question: I know that BRCA2 interacts with RAD51 to repair DNA damage.
But how exactly does it function ? What are the other proteins that interact with it ?
Answer: I'm just skimming through it now, but this 2011 review in Nature Reviews Cancer looks like it has everything you could possibly want to know about the BRCA1/BRCA2 pathway. If you don't have access to the journal, the first page of this Google search should have a PDF link to Researchgate down near the bottom, or you can try this direct link.
I apologize for the "link-only" answer, but there is a ton of info in the paper, and it would be rather difficult to summarize it in just a few paragraphs. This is a rather broad question, so perhaps you could read through the review and references, and if you still have specific questions about the pathways or interactions you can ask another question.
Comment: I agree with you, this paper offers a very good overview.
Answer:
Here is an image of BRCA2 and RAD51 oriented.( I produced this using PyMOL!)
The chocolate coloured part is some BRCA repeats. You can see how BRCA repeats and RAD51 are oriented. Here, the association is shown only for one of the 7 subunits of RAD51
The exact mechanism in brief :
.

BRCA2 binds to RAD51 subunits within the ring via BRC repeat mimicry of the RAD51 polymerization motif.

2.BRC repeats disassembles the ring.
3.The RAD51:BRCA2 comple is recruited to a DNA double strand break.
4.BRCA2 helps displace a protective protein, Replication protein A- RPA, and binds the primary ssDNA substrate by its B folds.
5.It loads RAD51 onto DNA. The handoff reaction might be facilitated by attraction of DNA by the positively charged BRC repeat helical arches.The BRCA2 helix-turn-helix domain(red) at the end of the tower may bind dsDNA in cis at the ssDNA/dsDNA intra-DNA junction (3) or in trans to the dsDNA that later serves as the homologous DNA template (6) and the positively charged arch may also help to attract the dsDNA template.
Source : Yang etal. 2002 , Shin et al 2003
Thanks to Nicholas Provert for teaching me basics of PyMOL on Coursera.

Functioning of BRCA2


Is there a generally accepted critical and/or feminist response to Heinlein's work?

Question: I personally enjoy reading Heinlein, but the argument has been made to me that "All of his women are basically men."  I have also heard it said that he basically tried to write forward-thinking literature (from a gender-equality perspective) and failed miserably.  Can anyone back this up (or refute it)?
Comment: People make a lot of claims about RAH, he was: Fascist, Sexist, Racist, couldn't write women, etc., but usually these people have only read a few of his works. (E.g., Fascism -- reconcile Starship Troopers with Stranger and RAH as a fascist.) Re: Women, I defy anyone to tell me that 'Puddin' (or Maureen and / or Podkayne, who were based on her) was basically a man. As a rule, his women were more competent than his men; less self-aggrandizing, perhaps, but overall smarter, more skilled and more capable. (Unsurprising in someways, if you know anything about Virginia Heinlein.)
Comment: There were times when he took heat for being too feminist. As a guest commentator alongside Walter Cronkite during an Apollo mission, he reduced Cronkite to spluttering by saying that women should be allowed to be astronauts.
Comment: Post modernist and associated critique can not be objective, by design.
Comment: Critics, especially feminists critics, are always quick to point out that any female character is both too strong and / or too weak, depending upon the particular critic. That particular line of thinking is sexist and limiting in its own right (attempting to define what femininity is or is not, when no such definition is either possible or desireable). In lieu of caring, I elect to ignore feminist critiques that concern themselves with 'how female is this particular character' as it is simply a waste of time.
Comment: and anyone taking one book and automatically disqualifying any argument that's backed up by it automatically disqualifies himself from the argument by definition.
Comment: [Damon Knight](https://en.wikipedia.org/wiki/Damon_Knight)'s essay on Heinlein is Chapter 7 in his book [*In Search of Wonder*](http://www.isfdb.org/cgi-bin/title.cgi?102735). The title of that chapter is "One Sane Man".
Comment: I was more looking for "this person has said he was/was not sexist for x reason."
Comment: "I Will Fear No Evil" backs that up pretty strongy, especially the first point (as part of the plot, no less).
Comment: We're looking for Good subjective answers here. Please back them up with a reputable source!
Comment: @Pureferret I thought we wanted objective answers? :)
Comment: @jwenting yes, in the most part, but 'good subjective' is acceptable too. As a mod I could put the spiel on the question. In short instead of the subjective "RAH was sexist!" you have "I think he is sexist because of [Point, Evidence, Explain]" It's still your opinion but backed up with facts and figures. tl;dr, as Objective as Subjective gets whilst still being subjective.
Comment: @MichaelBorgwardt - any comment about Heinlein containing a reference to *I Will Fear No Evil* is automatically void. Pretty much everyone agrees that, at the very least, it is by far his worst book.
Comment: @Donald.McLean: obviously, no single book can back up any blanket statement about an author's entire work, but I couldn't resist mentioning one that fits the statement in question so well...
Comment: @jwenting - too meta :)
Comment: @DVK we're in the metaverse after all, especially if we're now to generate objectively subjective answers. Or was that subjectively objective answers? ;)
Comment: I still remember to this day having a conversation with a fem lit professor when I brought up Heinlein.  The conversation changed.  Abruptly.
Comment: "Can anyone back this up or refute it?" No. These are not falsifiable claims, so the best you can hope is that people will pile on with more bafflegab, as has already happened, and more irrelevant facts from Heinlein's personal life (which does not inform your reading of his fiction).
Answer: First and foremost, I'd point you at Spider Robinson's essay on the matter in Requiem.
Then I'd suggest that you read Podkayne of Mars or Poor Daddy or The Bulletin Board.

Heinlein's female characters pick their own life paths and often choose to have both family and careers. They have aspirations to accomplish things in life and better themselves, they pursue education throughout their lives and work hard to fulfill the obligations that they have voluntarily assumed in life.
What was the problem again?

Now let's take

"All of his women are basically men."

Heinlein's works are full of smart, capable, empathetic, independent, strong willed women who are often wise and always know what they want and don't let men (or other women, for that matter) deter them from striving after those goals.
So, if someone complaining about this says that these traits make the female characters "men", then ... doesn't that amount to claiming that these are traits that are primarily masculine? Are you sure that this is a "feminist" position?
And if that is not the complaint, then has the author not portrayed women as having as many of the best qualities of humanity as his male characters?
Who's supposed to be the misogynist here, again?

Lets name some of these characters, shall we

Podkayne Fries in Podkayne of Mars (protagonist)
Hilde Burroughs & Deety Carter in The Number of the Beast (co-protagonist and both Ph.Ds)
Maureen Johnson in To Sail Beyond the Sunset (protagonist, Ph.D.)
Margerethe Graham in Job
Sadie Lipschitz AKA Hazel in The Cat Who Walks Through Walls
Friday Jones in Friday (protagonist)
Ishtar in Time Enough for Love (Administrator of the Howard Clinic on Secondus and a clinical therapist)
Barbara Farnham nee Well in Farnham's Freehold
All the female characters in Tunnel in the Sky and in The Moon is a Harsh Mistress

and on and on, I'd have to dig through my pile to find all the names.

I should note that Heinlein's female characters are rarely typical, but then neither are his male characters. Instead they tend to be unusually intelligent, highly educated (either formally or by voracious reading), broadly or deeply accomplished (or both), able to distinguish facts from guess and from wishes, and able to do what needs doing for the duration of the emergency.
I'd sure like to live up to that standard.
Comment: There are other issues with Heinlein's women that people point out. First, he does repeatedly emphasize in many of his novels that men and women are innately different in the workings of their minds and emotions due to their biological sex. This is an uncomfortable attitude from a feminist perspective, because... How, exactly? And is it proven, or just based on "well, it's OBVIOUS", suspiciously similar to sexist stereotypes, and probably fraught with confirmation bias? Still, he mostly seems to communicate that this doesn't affect women's competence, intelligence, etc in a civilized society.
Comment: (SPOILERS) Then, of course, there is the rape in Friday. I've always felt more squeamish over Friday's musings on motherhood, but she does literally say that the best option for a rape victim is to pretend to like it. On the other hand, she says she can consider this because she is trained and that it is a psychological tactic to lower her rapists' guard for her own ultimate benefit. On the other other hand, she also says she actually does almost enjoy sex with one of her rapists and later marries him. OTOOOH, she kicks his ass first.
Comment: Excellent answer, I wish I could upvote more than once.
Comment: But his narratives do suggest that it affects the work women are fit for in less civilized societies. Also that women are all naturally inclined to desire children and to nurture unless they have been traumatized. He writes that, for women, the strongest sexual desire is inseparable from wanting to breed. He shows that the most feminine women are frequently a little vapid due to being so preoccupied with all this. He suggests post-menopause is the best time seek a career for women. And that all right-thinking, truly feminine women will recognize and agree with these feelings.
Comment: @morewry I think [Donald McLean's answer](http://scifi.stackexchange.com/a/32093/231) is relevant to these musing. Heinlein was born and raised in a culture that held a lot of gender issues to be "obvious" that either would be taken as obviously bogus or suspect by modern standards. Heinlein presumably constructed these views from the statements of the women he respected who were also born in an earlier age.
Comment: I agree--but want to emphasize it's relevant to contextualizing the criticism, not to failing to make it in the first place. @dmckee
Comment: Chapeau! I like your kind of sarcasm. And yes, excellent answer, too.
Comment: Friday's a good example, really. I've always felt if you tallied it up, the good and bad in respect to sexism is about equal, and that there's value in speculative fiction that harmonizes heteronormativity with empowerment. It's understandable not everyone would agree with that, though. His work gets more complicated when you add in LGBTQIA+ considerations, though, in similarly ambiguous ways, but overall (I feel) with fewer positive counterbalances.
Answer: Although the answer by dmckee is outstanding, it is never-the-less incomplete. People who argue that Heinlein was sexist or lacked proper forward thinking forget about a couple of critical details.
The first is that he was born in 1907. He grew up in a time and a society that had certain views about women - what they should be like, and what they were capable of. Women in society have come a long way since 1907. Some of the significant parts of those advances have come since 1988 (the year he died). It is unfair to Heinlein to judge his "forward thinking" against modern standards - rather judge him against the standards he grew up with - those that existed prior to his 20th birthday.
Another thing to consider, is that he graduated from the US Naval Academy in 1929. When I was in the military in the 1980's, women were still, to an extent, second class citizens. Even today, most of the high ranking generals are still men. So, you can imagine that the Navy of the 1920's and 1930's wasn't exactly a bastion of feminism.
Consider the time frame in which his most well known works were published. The "juvies" were all written in the 1940's and 50's. Starship Troopers was published in 1959 and Stranger in a Strange Land came out in 1961.
Finally, I think it's important to keep in mind that Heinlein's writing is not necessarily an indication of his personal beliefs. Consider this remark in the Heinlein article in Wikipedia:

Heinlein's first novel published as a book, Rocket Ship Galileo, was
  initially rejected because going to the moon was considered too far out

Heinlein was a commercially successful writer and, at times, that required him to compromise for the sake of publication. Look at the publishing history of Stranger in a Strange Land.
So, while it might be true that Heinlein's works contain elements that seem antiquated by modern standards, we should also take into consideration not where he ended up, but rather how far he managed to get from where he started.
Comment: I have no interest in apologizing for Heinlein - there is nothing to apologize for. He believed in true freedom and equality among all races, all genders, and all religions. The fact that some people fail to see this because of a narrow minded focus on particular elements in fictional writing is their problem.
Comment: Those are all fine things to personally believe about an author, but unfortunately this doesn't answer the question at hand (hence the down vote). The question is "Is there a feminist critique of Heinlein's work?" Your answer seems to be that there shouldn't be, but doesn't address whether one exists or not.
Comment: I think the trouble with this answer is that by apologizing for Heinlein being a product of his time, by extension, you confirm the OP's fear that *his works* are also a product of the sexism etc. of his era, and probably not a very welcoming or relevant now to the same groups that were oppressed when he was writing them
Comment: Well, I'm a feminist, and this is my critique of his work.
Answer: I was searching around for some well-cited academic analysis and/or non-fiction Heinlein might have written that could clarify his intentions and beliefs relevant to feminist criticism and came upon this question. I can't do much more than round out the perspectives on Heinlein's general portrayals (as being mostly positive) with some canonical examples that highlight some of the (arguable) negatives.
I've edited this answer some over the years as I've read more Heinlein and to try to clarify the context of my answer. But I have taken it back to bare bones. This may make it easier to misunderstand, but as some misunderstandings are deliberate, there's little I can really do to prevent that.
Introduction
Despite the claim that "Heinlein's women are basically men," Heinlein repeatedly emphasizes in much of his work that men and women are innately different in the workings of their minds and emotions due to their biological sex. The TL;DR is that, despite a perceptively positive slant, Heinlein frequently depicted differentiation between men and women and reasoning for it "suspiciously similar" to traditional sexism.
Digressing momentarily to my opinion, I don't think the positive aspects of Heinlein's portrayals of women are to be found in either the absence of sexist stereotypes or in deeply nuanced characterization (that wasn't his strong point). Rather, Heinlein's narratives seem to say that many hallmarks of traditional gender roles are due to biology. But the take also seems to be, "So what?! If men can work, invent, govern, and fight under the influence of their hormones, so can women." This is not a bad message.
If that is the message. It's not clear if the gender essentialism in Heinlein's characters and plots comes from a traditionally sexist mindset, or if it was meant to cater to it, or maybe meant to say that different people will naturally have different perspectives and that their sex will influence those perspectives. Meaning is hard to pin down, thus my interest in Heinlein's own takes on his own meaning.
Sexist Memes in Heinlein
The following are canonical examples of "suspicious" portions that could appear to be sexist (and mostly, I think, disprove that "his women are basically men"). There are vague spoilers throughout. The majority cite narration, plot events, or dialog. The last cites a letter Heinlein wrote to a publisher. I haven't read as much of Heinlein's YA; maybe check out Heinlein's Female Troubles, which focuses on his YA.

His characters do suggest that sex affects the work women are fit for in less civilized societies--for their own good, of course--and aren't always "proven wrong." (Farnham's Freehold, The Number of the Beast, Time Enough for Love). Traditional sexist memes invoked: "Nature over nurture" and "Women need to be protected."
Also it is clear that, in Heinlein novels, all women are "naturally" inclined to desire children and to nurture them, unless they have been traumatized (Friday, Stranger in a Strange Land, Podkayne of Mars). Traditional sexist meme invoked: "Women are naturally maternal."
He wrote a couple of women who said that women get the most horny when they think about pregnancy and enjoy sex the most when pregnancy is a possibility (To Sail Beyond the Sunset, I Will Fear No Evil). Traditional sexist meme invoked: "Women's sexuality has ulterior motives."
Plot events suggest that women are so overwhelmingly attracted to powerful men that, without regard to their partners' feelings, they will deliberately seek out and nurture cuckoo's eggs if a sufficiently desirable mate appears (To Sail Beyond the Sunset, Time Enough for Love). Traditional sexist memes invoked: "Women will trade up to more powerful caregivers" and "Women are faithless."
Some characters seem to support the notion that the most feminine women are frequently a little vapid--although the justification might be their preoccupation with the very serious matter of creating the next generation (Stranger in a Strange Land, Number of the Beast). Traditional sexist meme invoked: "Women are silly."
Several women narrate that they are smart: smart enough to realize that, as women, it doesn't best serve them to flaunt their intelligence. Instead, they can deliberately let men think they are stupid and benefit from this because the men will do things for them while simultaneously underestimating them (To Sail Beyond the Sunset, Podkayne of Mars, Friday). Traditional sexist memes invoked: "Women are manipulative" and "Women use sex against men."
He writes of much older men who are attracted to barely pubescent girls (and vice versa) and implies via narration that this is very natural on both ends. Compounding this, girls as young as 12 are implied to have sufficient maturity to pursue this choice. How? The girls come back few years older and get laid (The Cat Who Walks Through Walls, To Sail Beyond the Sunset, Time Enough for Love). Traditional sexist memes invoked: "Men are way into young girls, but why shouldn't they be when the young girls pursue them" and "Women mature faster than men."
One novel suggests post-menopause is the best time to seek a career for women (To Sail Beyond the Sunset), since they no longer have better things to do. Traditional sexist meme invoked: "Building a family is the dream for women". Remember, in traditional sexist stereotyping, babies are always the most important thing for women. They are (or, one supposes, should be) important for men too, as members of the human species--but are so much more especially important for women that women can't/shouldn't/won't do anything else.
One narrative justifies a character abandoning his wife of many decades--in the process attempting to deprive his children and ex-wife of the vast majority of their communal money and property in favor of his new, young wife and his new stepchildren--on the rationale that he's just doing his duty by his new wife (To Sail Beyond the Sunset). Traditional meme invoked: "The domestic/caregiving role has no value compared to breadwinning."
Some of his female characters judge others who do not conform (especially to the obsession with motherhood), implying that all right-thinking, truly feminine women will sympathize and agree with their perspective--that any who don't are unnatural and unfeminine (To Sail Beyond the Sunset, I Will Fear No Evil). Traditional sexist meme invoked: "Women are catty."
At least one of Heinlein's juveniles, if you take Heinlein's own word in a letter to his editor, may be a parable for mothers who focus too much on their careers and too little on their children (Podkayne of Mars). Unless he was being sarcastic in the letter...dot dot dot. Traditional sexist meme invoked: "Bad mothers are ruining the world."

Most of these appeared in multiple novels, but they only scratch the surface of Friday and I Will Fear No Evil.
SPOILERS for Friday
There is a notorious rape in Friday. She does literally say that the best option for a rape victim is to try to enjoy it. On the other hand, she indicates that it's more pretending, says she can consider this because she is trained, and that it is a psychological tactic to lower her rapists' guard to aid her escape. On the other other hand, she also mentions finding one of the rapists almost pleasant and later marries him. On the other other other hand, she kicks his ass first and makes him admit to his crime (although OOOOH his apparently genuine remorse is overshadowed by, "you were so sexy I couldn't help it").
END SPOILERS for Friday
SPOILERS for I Will Fear No Evil
There are definitely some creepy overtones and unpleasant implications in the events of I Will Fear No Evil. To wit, an old man's brain gets transplanted into his beautiful young secretary's body: her body is now literally his and yet she's still in it. Her personality lingers in the body with awareness. She cedes control to him, however. Over time, the sex of his body changes how he thinks and feels: he becomes she. In some cases, what would have been offensive to him as a man became acceptable to her as a woman--even being talked down to and sexually harassed.
END SPOILERS for I Will Fear No Evil
On a closely related note, there are also noteworthy things in Heinlein's treatment of LGBTQIA+ characters. For example, he portrays homosensuality positively (Galahad, Mike the Martian), but wrote at least a couple scornful asides about homosexuality. Also, he portrays a certain amount of gender fluidity positively (Mike the Computer, Joanne Eunice, Slipstick Libby), but also seems to say it's dysfunctional if one's behavior doesn't match relatively traditional behavior deemed appropriate for one's sex.
Conclusion
I hope my examples show that Heinlein's work can come off as regressive today for good reasons. Still, I do personally think any writeoff of it as bad for/at women is as inaccurate as any vaunting of it as great for/at women.
As to the man himself, there's no doubt that some of the ideas he explores were ones he agreed with, but it's not clear from the novels alone which ones.
Comment: Thanks for this answer - it's thoughtful, balanced, but most of all doesn't let RAH off the hook for the problematic aspects of his work without discounting the value they do hold. And also speaks to my experience reading *Stranger in a Strange Land* sometime in the 2000s and not understanding why it couldn't take the next easy step into actual inclusion and equality, especially for LGBTQIA+ folks.
Comment: @dunraven One of the other answers mentions the context of his time and the constraints of commercial success with some interesting points. These works are pretty freaking old, and that obviously affects the author's subjectivity (though I think it's still responsible, fair, and fun to analyze from a modern perspective).  The idea that Heinlein-the-individual might have been more challenging, but couldn't be if he wanted to sell is interesting--and possibly there's some truth in it, but *shrug* possibly not, too.
Comment: @Martha Oh, maybe because I posted some of it in the comments on another answer. But I had more to say, so I made a longer post out of it.
Comment: "looking for the same information." The OP was looking for a critique, which is not information.
Comment: **** @JonKiparsky and morewry: [Be Nice](https://scifi.stackexchange.com/help/be-nice). Constructive discussion is welcome, but personal attacks will not be tolerated here.
Answer: Is the question really "and/or?" The question of whether there is a generally accepted critical response to his work seems to me to be very different from, and much more general than, the question of whether there is a generally accepted feminist response.
Assuming that the question is really and/or, then others have discussed the feminist response, so I'll say a few words about general critical response. I'm not pretending that this is comprehensive, expert, or up to date. Web searches turn up some interesting-looking stuff that I don't have access to, e.g., Dickinson, "What is One to Make of Robert A. Heinlein?" and Sullivan, "Heinlein's Juveniles: Still Contemporary After All These Years."
Science fiction doesn't generally attract the kind of critical attention received by non-genre literature. Ditto for young adult (YA) fiction. A lot of Heinlein's best writing, and arguably the portion of it that had the greatest influence on baby boomers, was YA science fiction novels, and therefore it was pretty much ignored critically.
There is a book by Alexei Panshin, Heinlein in Dimension, from 1968. This was written when Heinlein was at the top of his game and had shifted his focus from YA to fiction explicitly written for adults. James Blish writes in his introduction to the book:

On the one hand, [Heinlein] is so plainly the best all-around science fiction writer of the modern (post-1926) that taking anything but an adulatory view of his work seems to some people ... lese majeste [...] On the other, much of his major work gives the impression of being a vehicle for highly personal political and economic opinions, so that a critic who disagrees with these views may find himself reacting to the lectures rather than the fiction.

Panshin describes Heinlein (p. 8) as already being in "a period of decline and increasing alienation" from 1959 to 1968. Summing up (p. 189), he says,

It is clear right now that even if his career were to be over, Heinlein would retain a historical place in company with Wells and Stapledon.

Heinlein's work from 1970 on is at best controversial. A sample of negative critical response to work from this period is this review of The Number of the Beast by Dave Langford. Jo Walton calls one novel from this period "Heinlein's Worst Novel."
William H. Patterson, Jr., and Andrew Thornton have written "The Martian Named Smith: Critical Perspectives on Robert A. Heinlein's Stranger in a Strange Land."
Some critics simply find Heinlein dated, e.g., Jonathan Strahan in this review of Glory Road.


Does the value of a resistor matter when doing voltage division to cut it into a half?

Question: I have a 7.4V (8.4V when fully charged) battery that is connected to an Arduino and I need to monitor the battery. To do so, I need to plug the battery into an analog pin. However, that pin only accepts voltages from 0-5V, and returns a value from 0-1023. Therefore I want to cut that 8.4V when fully charged into 4.2V. I understand I need to use voltage division where the resistors are both equal, does it matter which resistors? \$10\text{k}\Omega-10\text{k}\Omega\$ vs \$1\text{k}\Omega-1\text{k}\Omega\$?
Comment: Roughly speaking the tradeoff in this case is the power consumed by the divider vs. the delay in charging the sample & hold in the Arduino.
Comment: Well you certainly wouldn't want to use 1Ω-1Ω because you'd be dissipating watts of power. You wanna size it small enough that you're not wasting power but large enough that it can drive the output.
Comment: As @copper.hat says, also consider the effect of I/O pin leakage. If the maximum leakage is +/-1uA (full temperature range) then 10K source impedance will affect the result by only +/-0.2%, which is pretty much negligible but significantly higher values of source resistance may be cause for concern.
Comment: See http://electronics.stackexchange.com/q/107741/11869 as well.
Answer: The Atmel data sheet says "The ADC is optimized for analog signals with an output impedance of approximately 10KΩ or less. If such a source is used, the sampling time will be negligible".
To have an impedance of 10K\$\Omega\$ or less, the resistors in the divider should be 20K or less. As others have pointed out, lowering the resistors consumes more power, so using 20K resistors makes sense to me.

simulate this circuit – Schematic created using CircuitLab
Edit: To explain the source impedance looking into the "middle" of the divider and the top:
If the top of the divider goes to a 'stiff' voltage (a battery in this case), the impedance looking into the center point is 20K||20K. You can think of it as 20K||(20K+Rs) where Rs is the source resistance of the battery (or whatever the top of the divider is connected to). Since Rs << 20K, it's very close to 20K||20K = 10K. If you were to disconnect the battery, (Rs  \$\rightarrow\infty\$) it would be 20K.
The impedance from the point of view of the battery (looking down into the divider) is about 20+20 = 40K, so the drain is only a couple hundred uA. That is because the input impedance of the ADC is very high and is in parallel with 20K, so it's about equal to 20K, and it's in series with another 20K.
Comment: @RobertHarvey If the top of the divider goes to a 'stiff' voltage (a battery in this case), the impedance looking into the center point is 20K||20K. You can think of it as 20K||(20K+Rs) where Rs is the source resistance of the battery (or whatever the top of the divider is connected to). Since Rs << 20K, it's very close to 20K||20K = 10K. The impedance from the battery pov is about 20+20 = 40K, so the drain is only a couple hundred uA.
Comment: Another thing to consider is adding a capacitor to ground right at the ADC input pin.  The ADC input is usually a switched capacitor input - a small sampling capacitor gets connected to the pin for some period of time, then disconnected and the charge measured.  The bigger the source impedance, the more droop that sampling cap will cause.  If you put a 'large' cap in parallel, the charge will come out of that cap instead of being pulled through the resistor, causing less droop.  This allows you to use larger resistors, limiting the current draw from the source, at the expense of bandwith.
Comment: In a voltage divider circuit with two 20K resistors *in series,* won't your impedance at the center point be 20K, not 10K?
Comment: @gbulmer ... done.
Answer: It doesn't fundamentally matter - you'll get half the input voltage regardless of resistor value. However, it should be obvious that if you use extremely large values, the amount of current the voltage divider will be able to source/sink will not suffice for the analog in pin, as it does have some, if very little, capacitance and leakage current.
So the goal is to find the maximum resistor value that will reliably interface to the arduino pin.
From my own experience I guess 10k resistors will do fine without wasting too much power.
Answer: Mathematically, it doesn't matter.  Two 1 kΩ resistors or two 10 kΩ resistors will both divide the voltage in half.
Practically, you should use the higher values, maybe going to 33 kΩ or 47 kΩ. The two 1 kΩ resistors will draw around 4 mA.  Two 47 kΩ resistors bring that down to less than 0.1 mA.
If run time is important, use the higher values, else use what you like or have handy.
I would put a 100 nF capacitor (maybe 10 nF for the larger resisitors) from the middle point to ground to filter out noise.
Answer: The rule of thumb to size the resistors is to make sure the bias current of the unloaded divider is about \$10\times\$ the load current to make sure the divider isn't loaded down too much (but the resistors are still as large as possible). This gives you two equations and two unknowns:
$$\frac{R_2}{R_1 + R_2}V_{\text{IN}} = V_{\text{OUT}}$$
$$I(R_1 + R_2) = V_{\text{IN}}$$
where \$R_{2}\$ is the lower divider resistor and \$I\$ is the bias current of the unloaded divider (which you set to \$10\times\$ the load current using the rule of thumb).
An improvement to the divider would be to add an op amp buffer to the output of the voltage divider:

simulate this circuit – Schematic created using CircuitLab
The op amp non-inverting input at the output of the voltage divider has a very low bias current so you can use very large resistors in the divider. If you choose an op amp with a very low supply current you can actually use even less power than you would need with the divider by itself. The trade-off is, of course, the added complexity of the op amp.
Comment: @copper.hat No, it is a switched capacitor input, not a high impedance input.  A small sampling capacitor is connected and charged up.  This capacitance will cause voltage droop if the source impedance is too high.
Comment: The value of adding the op-amp is so you can use much larger resistors for R1 and R2, which reduces the "wasted" current through the divider.
Comment: @PeteKirkham A few minutes searching yields the [LPV511](http://www.ti.com/lit/ds/symlink/lpv511.pdf): \$1.75\mu\$A max supply current at 12V supply, and it's unity gain stable. In any case, the question did not specify a load current so I included the op amp buffer tip.
Comment: the wasted current for dividing 8V by 2x20k is ~200uA, which is less than most low-power op-amps use. Do you know of a sub-100uA op-amp which would give a significant improvement? Also having an op-amp makes it harder to turn it off - without the op-amp you can easily either tie the high side to a gpio output or add a fet so the current is zero unless you are measuring the voltage.
Comment: @alex.forencich: I hadn't considered that. The atmega docs. list the analog input resistance for the ADC as (typ.) 100 MOhm, so I just assumed they had some internal buffering on the s/h... (However, it shows the 'analog input circuitry' as a switch in series with a '1...100 kOhm' resistor and a 14pf cap., so I'm now more confused that ever.)
Comment: I've removed my incorrect assertion that the input is an opamp already. Selective reading on my part.
Comment: @Null thanks - farnell's parametric search doesn't list supply current - did you use another parametric search or just happen to know what else to look for?
Comment: @PeteKirkham To find the LPV511 you can go to ti.com, click "Products" --> "Amplifiers and Linear" --> "Low Power Amp (<=500uA)" from the Product Tree. You'll get a table with rows of parameters, and you can dial down the Iq per channel parameter. Most IC manufacturers provide some sort of search table where you can adjust desired parameters, although they aren't always easy to find.
Answer: To determine the optimal value, you must know the input impedance of the A / D converter. Suppose that it has a value of 10k. If you make the voltage divider with two resistors 10k, it will work fine ... until you connect the A / D converter. Why? Because the input impedance of the A / D is comparable with the resistance of the divider. Then, following the example, if your A / D converter has 10k input impedance, the voltage divider in question, should be implemented with resistors 1k or even lower, so that when you connect in parallel the converter impedance of 10k, this value not appreciably affect the value of the divisor resistance.

simulate this circuit – Schematic created using CircuitLab
As schematics show, without the A/D connected
$$
V_O = \dfrac{V_{in}}{2}
$$
but if \$R_{AD}\$ is comparable with \$R\$
$$
V_O = \dfrac{V_{in}\cdot (R \vert\vert R_{AD})}{R + R\vert\vert R_{AD}}
$$
In short, the value of the divider resistors, should be as high as possible, but which is not affected by the value of the input impedance of the converter. A rule of thumb is that the divider resistor would be 10 times lower than the impedance of the converter.
Comment: In this case you are charging a cap., so the issue is not that the ADC input resistance distorts the reading, but that it takes longer to charge. You are correct that it is the impedance, but here this is 10-20pf.
Answer: Also, in addition to using resistors that won't load the battery too much, also consider the tolerance of the resistors in the voltage divider which influence the accuracy of the measured voltage. Tighter tolerance resistors will permit a more accurate measurement.


Network Printers Offline (but not really)

Question: I have two Ricoh printers/copiers setup for IP printing in the office. Before this week there were no problems printing to them. Now a handful of them (All running Vista, not sure if it is every Vista computer or not, It seems like I would hear more from users if that was the case), see both printers as being offline. All the PC's running XP have no problems printing. When this first occurred a reboot was able to get the printer to appear online, but that is no longer the case. (and at the time I thought only one computer was having the issue) I have removed the printers, reinstalled the latest drivers and there is no change on the Vista machines. I am currently using the same version of a RPCS driver on both VISTA and XP. As a work around I could setup the printers on a 2003 Server, but I don't see why IP printing should just stop working out of the blue like this. The printer can be reached by IP from all computers and the web interface is accessible and reports no errors. Does anyone have any ideas?
Comment: Do the "Standard TCP/IP Ports" on both the Vista and XP machines have the SNMP option enabled and the community set the same way?
Comment: That is a big 10-4.
Answer: If all else fails, you can disable SNMP monitoring in the printer's TCP port properties. You won't be notified when the printer becomes ACTUALLY offline, but you won't get false positives anymore.
Comment: This also happens if the SNMP community string is anything other than "public"
Answer: Hmm.
We've seen somewhat similar issues here, but outside of a few high-end plotters that we print directly to IP for, we're hosting the rest of them off of a printserver, and your symptoms are not exactly the same as what we've seen, but close enough. I've got a few ideas for you, in the hopes that they'll help but nothing really conclusive :)

1.) Try restarting the local print spooler service on the workstation in
  question. (ex: net stop "Print
  Spooler" && net start "Print
  Spooler"). See if that has any effect.
2.) Navigate to the driver properties of the printer, on the workstation,
  select "Advanced", select "Print
  Processor", try setting "WinPrint" to
  RAW, or changing to MS_XPS and select
  RAW.
3.) Check the port on the local workstations that the printer is
  configured to use, is it valid or did
  it mysteriously dissapear? (We've seen
  THAT one before. Man, what a pain!)
4.) It's a long-shot, but see if a local firewall is blocking it. Disable
  any local firewall/ip filtering and
  test to see if it works. We've seen
  this before, but specifically in this
  situation: We're running Symantec
  EndPoint on all workstations and in
  some instances, the local Windows
  default firewall was showing as
  enabled and running and doing some
  funky, funky blocking. :)

Either way, good luck!
Comment: it is 2018 and this is still an issue. Your net stop start worked for me , many many thanks!
Answer: Restarting Print Spooler service on the client did the job. Restarting the service on the server didn't work.
Our network: Win7Ultimate 64bit + a bunch of Win7Pro 64bit without domain, only workgroup.
Answer: Did you change the default snmp community (public) ?
Put it back online through the file menu once the printer is opened (or right click on it first.)
Comment: Nope, no changes to the SNMP. Toggling offline/online makes no difference.
Answer: I could resolve the issue by starting the SNMP Trap service which I had disabled manually (Windows 7).
Answer: This vista forum has two suggestions, one is to try and setup the printer port as 'persistent' using the dos command
net use LPT1 \\[printservername]\P1 /persistent:yes

The other is to apply the hotfix #934455 available from microsoft. This should be included in SP1.
Another site suggests restarting the Print Spooler service, which should reset the offline status. Also in the properties of Print Spooler / Recovery try setting the 'Recovery on Subsequent failures' to Restart. The default is it stops restarting after 2 failed attempts.
Comment: They are running SP2.
Comment: Did you try the other suggestions?
Comment: I am not using a print server so that eliminate net use. I tried restarting the print spooler service and it didn't fix the issue.
Comment: But are you still using IP printing, so it still creates a virtual port.
Answer: I had the same problem with a 2008 Server machine (basically Vista Light), I had to reboot it before it would print. Talk about aggravation. There is a registry setting hidden deep within the bowels of HKLM
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet\Hardware Profiles\0001\System\CurrentControlSet\Control\Print\Printers\

Find the offending printer entry, then find the entry named.
PrinterOnLine

Edit it. Changing it to the magical value of
1

This makes my cry for CUPS ... or even lpr ...
Comment: If you try it, don't use HKLM\System\ControlSet001, but HKLM\System\CurrentControlSet, which is a link to the ControlSet that is actually active on your machine.
Comment: Hmm, I'll have to check this out.
Answer: In my case printer was seen by windows 7 as offline when someone was trying to print using wireless lan. In wire lan everything was ok and also it worked on Linux even withs wireless lan connection.
I found out that widows 7 use snmp to determine printer state, after unblocking snmp communication (of course only for printer) on our firewall it works perfectly whether client is in wire or wireless network and on with every OS.
Answer: Had the exact same issue in W2K3. I unchecked the snmp option and the printer went back online.  (Had the regedit as well.)
Answer: Had the exact same issue in server W2K8 also. Local network, no routers, no filters, no firewalls, no natting. All on the same broadcast segment. Since last friday (5/24) all network printers stopped printing from the printer queue in the server. Restart print spool service had no effect. Unchecking the snmp option in the server's port settings did the job.
Answer: I found i had disabled SNMP in the web interface and had changed the SNMP community name on the printer when i reenabled, as soon as i changed it back to public to match the communication port settings on the printer driver. It came back online.
Answer: An update to my laptop's antivirus software which contains a firewall ended up being the culprit.  It started blocking the spooler service after the update.  I had to allow the spooler service access through the firewall and it started working fine again.
Answer: the problem might be that your router is reassigning the ip that the printer has acquired. this might be because you turn off your printer after use and also your router. you only have to reassign an ip to your printer and my advice is that you reserve it by your router.
and never face this problem again.


Use different memory capacity RAMs in mac mini

Question: I have a mac mini with 2GB RAM and want to buy another stick (since mac mini only have to memory slots) of 4GB (all other specs are the same), will it cause a problem?
Thanks,
Matt
Comment: See if this is your model, and you can see the difficulty: http://macminiramupgrade.com
Comment: Can you tell us what version of the mini you are going to upgrade. The older versions (pre 2010) are rather difficult to open up.
Answer: You need to find out what RAM your computer is capable of handling before you just start putting RAM into it, even if the speeds are the same, it's never to much trouble to be careful and do a bit of research to make sure things go smoothly.
Thankfully there are a lot of websites that have already tested these things for you so that you don't make any mistakes.  I usually go to:
http://www.crucial.com/store/drammemory.aspx
They have a system scanner service that will scan your system and check your settings, it will redirect you to a page where you can buy RAM, you don't have to obviously, but it will show you all the RAM configurations that your system supports.  It will let you know the max RAM capacity, if you don't see 4GB as an option, then it doesn't support it.
If you don't want to use the scanner you can also just input your make model year and cpu to get the same results, though the scanner is usually more accurate if you aren't sure which machine is yours. They do tests to make sure the RAM is compatible and list all the speeds and configurations for the RAM so you know which ones to get.  Make sure everything matches up before hand.
Knowing these things will help you find out if the RAM you have or are about to purchase will work so that you don't waste your time.  I hope this information helps you out.
Answer: The answer is no, it shouldn't. I have a Mac Mini 2009 that I replaced with 2 X 4GB of RAM, with absolutely no problem. You may get a warning that your RAM is not optimally configured, but it shouldn't actually cause any errors (unless you don't install it correctly).
Comment: 2 x 4GB is (potentially) different from 2GB + 4GB, though.
Comment: True. However, I installed them one at a time (I previously had 2 X 1GB) and everything worked fine. I don't know about the warning because I don't know what OS version he has.


Attempt to download app, says it's already installed on my Iphone4

Question: I had the sirusxm app on my phone and everytime it would give me problems I would delete it and reinstall it.  I forgot that I had just recently changed my email password from my laptop, which is synced with my phone.  When I went to download the app after having once again delete it due to having problems, the column which you click on to download quickly changes to purchased.  The app is not on my phone.  How can I get it?
Comment: How many apps do you have on your phone? Is it possible that you just missed it? Have you tried using Spotlight to search for it?
Comment: +1 for searching. It may be on an "invisible" page, if you have enough apps installed.
Answer: There is a difference between an app that has been purchased and one that is installed. To install a purchased app, open the App Store app on your iOS device.
Click on the Updates button in the lower right corner to advance to the Updates pane:

Click in the Purchased area near the top of the screen to advance to the Purchased pane:

Select the Not on this iDevice tab to see purchased apps that aren't currently installed:

Select the app you're looking for from the list and install it.
Answer: When I get to the "Not on this iPod" folder, the app (instagram) I am looking for has an action button that is greyed out. iPod Touch 4th Generation. I have tried to sync via cable with iTunes and no change. I have tried to remove the app from our iTunes and re-sync and also no change.
Background: My niece plugged her iPhone into our iMac a long time ago and some of her apps are on our iTunes and they load to our devices. Instagram was one the apps.
This would seem related to the problem. Unless Instagram is not able to run on an iPod Touch.
Answer: Search for it on your phone using Spotlight. As mentioned in the comments, it may be on an invisible home screen. If that doesn't work, you can try using iTunes to sync it over, or at least to help you find it.
If you'r absolutely convinced that it's not actually installed, you can try using a utility to muck around with system files. (Particularly, the SpringBoard property-list files, which may contain info that the App Store is using, although honestly, I doubt that doing so would work.)
Answer: Have you tried searching for the application on your device? If you have enough applications installed, some of them may not be shown on the home screen. You can search by swiping to the left from your first page of apps.

You can also check iTunes to see if the app is installed, and uninstall it there:


Having the same equivalent class imply that the elements are equivalent?

Question: You have given that the equivalence class of $x$ and the equivalence class of $y$ is equal. $[x]=[y]$. Does this imply that $x\sim y$? If yes, how do I prove it, if no, what sort of counter-examples can I give?
Answer: By definiton of the equivalence class of some element, we have
\[ [x] = \{z \in X \mid z \sim x\} \]
By reflexivity of $\sim$, we have $x \in [x]$. So $y \in [y] = [x]$, that is $y \in [x]$, so by definition of $[x]$, $y \sim x$.
Answer: Yes. If $[a]$ and $[b]$ are equivalence classes, then either $[a]=[b]$ or $[a]\cap[b] = \varnothing$.
Equivalence classes always form a partition of the underlying set: every element $x$ lies in exactly one equivalence class.


How to get help on stats when reviewing a paper for publication

Question: I'm reviewing a paper for publication at the moment and I find the statistical methods in it quite questionable. But I've only got limited experience and don't want to call them out on something that isn't actually wrong either. So I'm wondering about the best way to ask for help on the main site. That is,(a) is it even ok to ask the equivalent of "Am I right that you can't analyse X using Y?", (b) how do I best go about keeping confidentiality, and (c) are there any other tips for how to best deal with this sort of problem on CV?
Comment: (+1) To a great question. I wouldn't normally suggest this, but you might consider posting a modified version of this question to the [academia.SE](http://academia.stackexchange.com) main site. You might make it slightly less SE-centric (though mentioning it as a special case). There are some very thoughtful CS researchers active on that site, so you might even get a more specialized response. If you do post such a question, please provide cross-links in both places.
Comment: I have very little experience in reviewing papers. Would it be inappropriate to just say to the editor something like "I have doubts about the validity of X, but my knowledge of statistics is insufficient to say for sure"?
Comment: @mark999 I don't think it would be inappropriate, but I would be wary the concerns might just be brushed aside and, if they were justified, the paper be published with incorrect and misleading stats. Most stats in my area of CS are woefully inadequate, as neither authors, not reviewers, nor editors, seem to have the necessary statistical background to do them right. Therefore, unless you can back up your concerns with cold, hard facts, I wouldn't expect the editor to reject a paper because one reviewer thinks they might have gotten something wrong.
Comment: @ThomasH Thanks for your reply.
Comment: Here is a question that does what you propose: http://stats.stackexchange.com/questions/14416/as-a-reviewer-can-i-justify-requesting-data-and-code-be-made-available-even-if
Answer: Although @cardinal raises some good points, I think some questions could be germane to CrossValidated, as long as things are handled appropriately.
Please please please do not post an entire manuscript, or even big excepts from a manuscript, and ask for critiques. I think this is Cardinal's major concern and it is a very valid one. Among other things:

It is ethically dubious and violates your agreement with the authors/journal.
It might 'out' you as the reviewer (if you work in a field with anonymous reviews)
It is unlikely to work anyway: I doubt many people here would be willing to spend hours plowing through a manuscript in order to write your review for you.

All that said, I think it would probably be fine to post specific and general-interest questions, particularly if done in a way that doesn't reveal too much about the original manuscript. For example, I think a question like this would be okay:

I am reading a paper where the authors use a False Discovery Rate procedure to compensate for a large number of multiple comparisons. I was under the impression that the Benjamini–Hochberg procedure only worked for independent tests, but there are some arbitrary (i.e., positive and negative) dependencies between their tests.
Can this procedure be used on dependent tests? If not, are there any similar alternatives?

This question is answerable (in fact, it has already been answered here!), it is not too localized, and it probably would not violate any confidentiality agreement you have with the journal.
All that said, I think this a somewhat thorny issue and I hope others weigh in. Thank you for trying to be as conscientious a reviewer as possible! I'll buy you a drink if we're ever at the same meeting!
Comment: (+1) I wholeheartedly agree that generally applicable questions like the one you give as an example are acceptable, on-topic and interesting. If it can be done in this manner, that's great. I suspect many such questions would be hard to abstract out appropriately without losing important context, though.
Comment: @Matt Your example is precisely the kind of question I had in mind - general applicability of statistical procedures in certain contexts. As it is, I had to already submit the review and noted my statistical concerns, which I had confirmed through general web searches. But, in this kind of situation in general, I would like to substantiate my review with a statistical reference as, in my area (general computer science), proper statistical knowledge is usually missing, even among reviewers, and I would rather point authors in the right direction than just telling them they're wrong.
Comment: @Cardinal: Glad you agree! I'm not sure about the question quality. On the one hand, I'd hope that people far enough in their career to referee manuscripts could also put together a solid question (vs, say, a college freshman asking for help with Stats 101). On the other hand, the peer review process is so rarely full of pleasant surprises :-/
Answer: With some regrets, I think this should be strongly discouraged on this, or any other, site.
First the regrets: An obviously conscientious reviewer taking the time to get feedback on a paper up for publication is probably much more likely to post a well-expressed, interesting statistical question. From a selfish perspective, I'd much rather read and think about such questions and they'd almost certainly increase overall site quality. I'm pleased that you would consider this venue and equally pleased that you took the time to ask about it here on meta first. There should be more reviewers like you in this world.
Now for the discouragement
As you know, reviewers are given a big responsibility and, as a form of compensation, get continuous first contact with new research advances. Confidentiality is one of their biggest and most important responsibilities. I think doing anything to potentially breach that, even unintentionally, is treading on very thin ice.
Here are my suggestions.

Know your journal's policies. Many (maybe most) journals have strict policies on sharing manuscripts under consideration, even in private. While often these are "softly" ignored (some reviewers may pass off certain MS under review to graduate students), you should know the policies and be comfortable that whatever action you take meets them.
Don't overburden yourself. Double check with the associate editor handling the paper to see if there is a separate statistical reviewer. In many fields, particularly those allied to medicine, this is common practice and lightens some of this burden placed on other reviewers. That said, if you have concerns about the statistical methodology and can clearly enunciate them, they will still be taken into account when the AE makes their decision.
Think globally, act locally. If there is no statistical reviewer, or you simply want to do so, seek out some assistance at the local level. If in (or near) academia and you have access to a statistics department or a statistical consulting service, visit them or send an email to people working in relevant areas. This lets you carefully control access to the manuscript and you can even have them sign something more formal to protect confidentiality, if needed. If in industry, presumably you have contact with statistical practitioners that might be able to help in a similar manner.
Use the network, but not the (inter)net. If there is a contributor here that you believe you can trust, you might contact them privately to see if they would be able to help. You should work out, in advance, what if any attribution should occur.
As a very last resort, play the anonymous interested reader, with extreme(!) care and caution. If and only if an identical copy of the manuscript under consideration is posted to a public permanent archive (like the arXiv) or similar, then formulate your question as one of an interested reader unsure about some portion of the paper. This is still fraught with complications. You will have to wrestle with how to incorporate the feedback you get in a way that (a) meets your ethical thresholds, (b) meets the standards of required attribution as detailed by this site's copyright and content-sharing license and (c) will not subject you to the possibility that the author will see your report and then later happen to find the associated question on CV and be able to identify you. If you have any doubts, you should run it by the AE first. My opinion is that this is a minefield that is best avoided.

NB: I have consciously written this post employing a rather strong tone, but it merely reflects my opinion and shouldn't be taken as authoritative. Hopefully some of the thoughts will be helpful as you think this through.
Comment: Thanks for your insights and suggestions. Confidentiality is my main concern in this. I was only thinking of posing a general question (e.g. "I thought test X is inappropriate with a statistical design Y") but since I am trying to "ask in the negative", so to speak, I wasn't sure if that type of question is ok on CV without giving some motivation as to why I'd be asking.


I'm thinking of getting a new car ... why shouldn't I LEASE one?

Question: Why is leasing a car a bad idea?
Answer: If you are looking to build wealth, leasing is a bad idea.  But so is buying a new car.  All cars lose value once you buy them.  New cars lose anywhere between 30-60% of their value in the first 4 years of ownership.
Buying a good quality, used car is the way to go if you are looking to build wealth.  And keeping the car for a while is also desirable.  Re-leasing every three years is no way to build wealth.
The American Car Payment is probably the biggest factor holding many people back from building wealth.  Don't fall into the trap - buy a used car and drive it for as long as you can until the maintenance gets too pricey.  Then upgrade to a better used car, etc.
If you cannot buy a car outright with cash, you cannot afford it.  Period.
Comment: I think this is a bit hyperbolic.  If you are able to save money, invest money, and still pay the monthly payment on a nice car, I think you're okay.  Now, if you're paying $600 a month on a car and have $0 in savings, then thats roblem.
Comment: This says nothing to answer the actual question of "Why is leasing a car a bad idea?"
Comment: If you are able to save money and invest money, then you would be much better off buying the car with cash and then investing the money you would be using for payments.
Comment: @DJClayworth That is not always the case. Obviously if you can invest and see a larger return than the actual interest cost of loan, than any mathematician will tell you to take the loan. Problem is there is risk and your return on your investments is not likely guaranteed.
Comment: While its true that new cars used value once they leave the lot, you're paying for a little more peace of mind that hopefully the car has fewer "surprises". This is also why you pay a little more for used cars from a reputable dealer then from a private individual.
Answer: You SHOULDN'T lease one if you are going to get an economy car, if you don't drive too much (<15K / year), and you want to hang on to the car for a long time.
Otherwise, if you are a regular driver, driving a leased new quality car can be cost effective.
Many cars now have bumper-to-bumper warranties that last as long as the lease (say 80K). So there is rarely any extra costs apart from regular maintenance. The sweet spot for most new cars is in the 5th, 6th, or 7th years, after they are paid off. But at that point, you may find you have maintenance bills that are approaching an average of $200 - $300 per month. In which case, a lease starts to look pretty good.
I owned a 7 year old Honda Accord that cost only $80 less per month in maintenance than the new leased VW that replaced it.
Haven't looked back after that. Into my 3rd car and 9th year of leasing.
Comment: One big piece of work can easily push the average maintenence cost to $200 per month.
Comment: $200-$300 a month in maintenance on a Japanese car?  I sure didn't see that.  My wife's 9 year old Civic cost us nothing outside of the normal checkups & oil changes the last few years before we got rid of it.
Comment: @Jim i had the transmission go on my acura, 3500, which averages to almost 300 per month.  Fortunately the repair shop had a free loaner car, or i would've needex to rent on top of that.
Comment: $200-$300 per month for maintenance on a six-year-old car? What are you driving? My 14-year-old CR-V with 150,000 miles on it costs about £400 per _year_.
Answer: Here are the reasons I did not lease my current car.

When you lease, you're tied in at a monthly payment for 48 months or more. The only way to get out of that payment is to transfer the lease or buy out the lease. If you buy/finance, you can always sell the car or trade it in to get out of the payments. Or you can pay down more of the vehicle to lower the payments.
Most leases calculate the cost of leasing based on the 'residual value' of the vehicle. Often these values are far lower than the actual worth of the vehicle if you owned it for those months and sold it yourself. So when you do the math, the lease costs you more -especially with today's low financing rates.
Comment: #2 is only correct if you simply trade in your lease without knowing the value of a car.  The lease itself does not lock you into this action or line of thinking, and if it is *indeed worth more*, you can sell it yourself and pay off the residual at the end, pocketing the difference.
Answer: Also consider how cars fare under your ownership:
Does your current car...

Have flecks of yellow paint on the bumper from that tight corner of the parking garage?
Have stains from baby vomit, pets, spilled coffee or oil marks from drive-in movie popcorn?
Have Scratches and dents?
Live outside, exposed to the elements?
Frequently get parallel parked on the street overnight?

If any of the answers to these questions are "Yes", you're probably going to get hosed with fees when you return the car.
Answer: I agree with Speedbird389 - I leased an economy car 10 years ago, paid the residual at the end of the lease because I knew the car would last a long time, but that cost me $5000 more than if I had bought it in the first place...
Comment: @JaimeS:  If you agree with an answer you can just upvote that answer and add comments if you desire.  This way the question doesn't get duplicate answers and the strongest answer will float to the top.
Answer: I never understood why people lease rather than buy or finance.  I'm financing a new civic 09 @ 0.9%.  At the end of the 5 year terms I will have paid less than $800 in interest.
Comment: One of the reasons people look at leases is the *cash flow* aspect -- their monthly payments could be lower.  But yes usually they ignore the cost of financing, to their detriment.  And auto dealerships are usually complicit in steering people towards leases by having them think in terms of *monthly payment* and not *overall cost*.
Comment: Some people also forget the option of a proven old time classic idea of saving up for a purchase to afford it.
Comment: I just got out of school and the best they offered me was an 8.6% rate. Meh. I paid it off early, though. :)
Comment: I would lease because I drive about 4000 miles a year, and only paying $350 for a Lexus seems fine to me.  Financing it would cost me $600 a month.
Comment: Indeed, many people cannot envision a life without an automobile payment, whether it is for a lease or a purchase. A monthly auto payment is just a fact of life, like the rent or mortgage payment, or the tax withholding. Auto dealerships know this well, and that's why, as Chris Rea cogently points out, dealerships push people towards leases by showing them that the monthly payment is smaller with a lease than with a purchase. If an auto payment is always there each month (like rent or mortgage payment or tax withholding), why not get the smallest payment possible?
Answer: I have an eight year old Kia Spectra that my wife is after me to replace -- but it hadn't been giving me any trouble at all.  Soon after she started telling me I should replace it soon it started having problems; compressor, tires, and so on.  How did she know?
Anyway, so now I'm looking -- not ready to buy yet, but I'm looking.  The reason I won't be leasing is mileage.  I live 45 miles from where I work, so with incidental driving, I put at least 100 miles a day on a car.  That's about 26,000 miles a year if I do nothing but drive back and forth to work.
On a monthly basis the lease is advertised as being less than most payments, but that is with a mileage limitation.  Since most leases I've looked at top out the mileage well below that mark I won't be leasing.
I am looking at the new cars that are available now -- but I don't plan on buying until next year, and buying a lightly used car that is only a year to two old.  So I'm looking at what I will be buying while I can still find information about them.
So yeah, mileage is a strong reason why I'm not considering leasing.
Comment: `How did she know?` (In my best Bugs Bunny voice) Diia-boh-lickal sabo-tay-gee.  Seriously though, I'm surprised it lasted that long without any trouble.
Comment: yeah, so am I.  At just under 150K miles it started falling apart.  I'm now at 160K miles and beginning to doubt it will last till next year -- but that is the plan I'm stubbornly sticking with.  Car shopping ranks just right under job and house shopping on my list of least favorite activities.
Answer: It's a very simple equation. If we forget about the stress and limitations that come with the so-called "lease", and make the following assumptions:

if we lease, then we will return the car after 3 years to the dealer
consider the worst case scenario mentioned above, that the car will lose 60% of its value in 4 years (I'll take 50% in 3 years)
The lease is $300 a month while financing is $600 at a negligibly low rate (around 5%)
the original car price was $28000

Then after 3 years of using this new car:

For leased car, you have paid $10800 and ended up with nothing
For financed, you have paid $21600, but own most of the car (financing average is period is 4 years), which can be sold for 50% of it's original price which is $14000, so the net loss is $21600-$14000=$7600 which is, with all the extreme assumptions we made for financing, would be so much less than the leased car!!!

I will never understand why people still "lease" a car. Even for very low income people who have to have a car, financing a per-owned decent car would do, but it's just "show off" seduction and lure that either unknowing minded or idiot teenagers fall for.
Comment: Good math.  Typically low income people tend not to be "well qualified buyers" which makes their payments higher.


Get the length of the current status line

Question: While I was customizing my status line, I was wondering if I could make certain elements of the status line disappear if the window width is too small.  To do this, I would have to know how much space the status line is actually taking up.  Is there a way of doing this?  If not, is there some other way of hiding/showing certain elements of the status line if the window is squishing its contents?
Answer: While I'm not a statusline connoisseur, I think the general idea is to do it "the other way around": while computing the statusline, the evaluated code (functions etc.) could check for Vim's windows width and decide if (or how) a certain information will be displayed. To put it in a silly way, something like this:
:set statusline=%{winwidth(0)>80?'looooooooooooooooooooooooong':'short'}

Every time Vim's windows width changes, the status line will be re-evaluated and will display the adjusted information.
In other words, if you want to know the length of the statusline, you will kind of ...have to keep track of it while building the expression to be evaluated (since that's the place where you have the "total" control). Slightly less sillier example:
:set statusline=%{len(expand('%'))>winwidth(0)?expand('%:t'):expand('%')}

(show full filename path if shorter than the window width, or only the actual filename if not). In practice, functions should make such a build-statusline-while-checking-its-length easier.

After some digging - and if I understood it correctly - this seems to be the approach used in the vim-airline plugin:
let s:section_truncate_width = get(g:,
  'airline#extensions#default#section_truncate_width', {
  \ 'b': 79,
  \ 'x': 60,
  \ 'y': 88,
  \ 'z': 45,
  \ })

function! s:get_section(winnr, key, ...)
  if has_key(s:section_truncate_width, a:key)
    if winwidth(a:winnr) < s:section_truncate_width[a:key]
      return ''
    endif
  endif

  [...] " other code, returns section text
endfunction

(if a section has 'truncate width' key in the dictionary, and window width is smaller than that width, the section isn't displayed)
Comment: The part about knowing the length of the status line when building it only works when it doesn't contain things like `'%c'`, since those are calculated by vim afterwards.  However, those special status line characters can be emulated by vimscript most of the time, it just removes the convenience of them.
Comment: Yes, that's inconvenient (and can be circumvented, as you say). That's why I used `expand('%')` as example, instead of `%f`. The thing is, Vim doesn't seem to allow peeking at the *evaluated* statusline anywhere (e.g. to get its length).
Answer: It doesn't answer your question about the length of the status line, but Vim should manage this for you: are you aware that 'statusline' has a potential < item you can include? It indicates where to truncate the status line if it's too long. See :help statusline for more information.


Who wrote the book of Genesis? (Overview)

Question: I've heard reference in other questions on this site that seem to indicate a belief that Genesis was written by "the same man."  What do we actually know about wrote Genesis (whether a single, or multiple authors)?
Comment: At least do the man a favor and link the question you're referring to. It's good practice and could contribute to any answers.
Comment: related: http://christianity.stackexchange.com/questions/2246/how-valid-is-the-jedp-theory
Answer: There are two theories:

Traditionalists
Tradition says that Moses wrote the Pentateuch, including the book of Genesis.
Here is a lengthy argument for this.
JEDP Theory
Some modern scholars believe that Genesis (along with the rest of the Pentateuch) was written by a series of authors.  The idea comes from the fact that God is referred to using multiple names (such as Yahweh, Elohim, Yahweh Eloheinu, etc.).
The idea is controversial based on (1) the fact that it goes against tradition and (2) the fact that even today we use multiple names for God ("our Heavenly Father", "God the Father", "God", "Jehovah", etc.).

Those are the two main theories.  Unfortunately, we don't have any way of truly knowing who wrote Genesis.  That's the reason for the varying theories.
Comment: The documentary hypothesis isn't just based on different names being used for God, it that there are often two varying accounts of the same events and the style and perspective differs between each account (along with what they call God)
Comment: My reading about JEDP suggests that Genesis would have had at most 3 authors according to this theory, since 'D' only wrote Deuteronomy. Is this an accurate understanding of the theory?
Comment: Hmmm, yes I believe you're right!  [Here](http://en.wikipedia.org/wiki/Documentary_hypothesis#After_Wellhausen) is a graphic that shows the authors of the first four books, excluding Deuteronomy.  It looks like there was a fourth set of editors called "Redactors", that seemed to have actually generated a small amount of text.  However, they are separate from the ('D') Deuteronomical historians.  I've edited my answer just a hair, based on this new understanding.
Comment: Yahweh Eloheinu is not used anywhere in the Pentateuch. Yahweh Elohim is used in Genesis 2 exclusively, to introduce the Yahwist narrative, to identify Yahweh as "Elohim", as God.
Answer: Tradition says Moses compiled the book of Genesis, along with writing the rest of the Torah.
However from Wikipedia:

Tradition credits Moses as the author of Genesis, Exodus, Leviticus, Numbers and Deuteronomy, but the books are in fact anonymous and look back on Moses as a figure from the distant past;[3] some traditions contained in Genesis are as old as the United Monarchy, but modern scholars increasingly see it as a product of the 6th and 5th centuries BC.[4]

It is rather unclear who actually put the words to paper.
This Answers in Genesis article argues that Moses did indeed write Genesis:

Ultimately, the author of Genesis was God, working through Moses. This does not mean that God used Moses as a 'typewriter'. Rather, God prepared Moses for his task from the day he was born. When the time came, Moses had all the necessary data, and was infallibly guided by the Holy Spirit as to what he included and what he left out. This is consistent with known history, and with the claims and principles of Scripture (2 Timothy 3:15–17; 2 Peter 1:20–21).

The answers in Genesis article claims to prove this conclusively. However, I think the best we cay say is that we are unsure.
Comment: @Richard As a programmer I wholeheartedly agree.
Comment: I'm not sure I trust that site to be very objective, considering the sub title ("A deadly hypothesis...") and the opening sentence ("Nearly all liberal Bible colleges...") I take both of these to mean the site is stating its bias, before it even begins to answer the question. I'd rather see something that at least _pretends_ to be objective. (Note that I'm _not_ saying their answers are wrong)
Comment: I'm not discounting their result (It may be completely true and accurate); but when I hear "a computer says", I pretty much *always* question the result.  Computer programs are written based on a set of assumptions and therefore tend to be as faulty as the programmers/scholars who wrote them.  Still... +1 for a nice answer.
Comment: @wax eagle: It ought to be possible to do (and report on) a study on this subject matter in an objective fashion. I don't buy "It's a rebuttal" as an excuse for being intentionally one-sided.
Comment: The process of redaction, which Genesis has undergone several times, makes it very difficult to figure out one author because it's hard to tell what are the traces left by the editors and what is "original". I don't think we're going to know much more about this since we do not have a record other than that these text did undergo redaction.
Comment: Nice answer... I wonder if we can conclude (more conclusively) if it was authored by a single person, or multiple authors.
Comment: @Flimzy - if you read the Answers in Genesis article I linked to they claim a computer says it was 1 author.
Comment: @Flimzy - I do not present them as an objective source, and I never will. They are as biased as they claim the people who they are opposing are.
Comment: @Flimzy - I am on the lookout for a more reliable source. If i encounter one I will post a quote.
Answer: Genesis/Exodus/Leviticus are a compilation of several narratives, all dating to the 10th century BC or thereabouts, which are evident by the seams in them, and by the radically different styles. They are considered to be compiling Jewish narratives to make a unified tale which will bring the disparate tribes together in a kingdom.
There are three major threads:
Yahwist (J)
This author is first rate, one of the greatest writers in history, if not the greatest. She writes about God in a very visceral, fully embodied fasion. She tends to emphasize the stories of women, providing first person internal monologues from the point of view of Eve, Rebecca, Sarah, and provides a wonderful story of female attempted seduction in Genesis 39. For this reason, I refer to her as a "she", although this is obviously uncertain.
You can identify J easily by reading the narrative. There is no doubt when she is writing. She consistently uses "Yahweh" as God's name, or "Yahweh God" in Genesis 2. She writes internal monologue and easy natural dialogue. She tends to write stories of women in detailed human terms, and of men in distant heroic terms.
The quintessential Yahwist narrative is exemplified by the following passage in Exodus, chapter 33, verses 17, in my translation, available here :

And Yahweh said to Moses: "Also this thing that I have spoken I will do, because you are pleasing to me, and I will know you by name."
And he said: "Please show to me, your honor."
And said, "I will bring by all my goodness in front of you, and I will call on the name of Yahweh in your presence, and I will grace that which I will grace, and I will feel for that which I will feel for."
And He said: "You could not see my face, because a man will not see me and live."
And Yahweh said: "Here is a place filled with me, and you will post yourself against the rock. And it will be as mine honor will pass, and I will put you in the nook of the rock, and I will lean my palm against you until I pass.And I will remove my palm, and you will see my back, but my face will not be shown."

The idea of seeing God's back, as He is moving away, lifting an enormous palm from a nook in the rock to uncover his mighty passing form, is simultaneously beautiful and haunting, and masculine erotic.
Elohist (E)
Elohist has a less fleshy description of God than J, and the drama is not as tense. Elohist writes about blessings and omens a lot. Here is some E (Genesis 48, in my translation, available on Wikisource ):

And Joseph took the two of them, Ephraim in his right hand, to the left of Israel, and Menashe in his left hand, to the right of Israel, and he approached him. And Israel sent his right hand and placed it on Ephraim's head, and he is the younger, And his left hand on Menashe's hand: with consideration upon his hands, because Menashe is firstborn.
And he blessed Joseph, and said: "The God in whose presence my fathers came before, Abraham and Isaac, the God who has shepharded me from before until this day, the angel who spares me from all harm, will bless these youths, and will call into them my name, and the name of my forefathers Abraham and Isaac, and they will multiply in the face of the land."
And Joseph saw that his father had sent his right hand on the head of Ephraim--- and this was wrong in his eyes. And he supported his father's hand to take it off the head of Ephraim, to Menashe's head. And Joseph said to his father, "Not so, father, because this is the firstborn, put your hand on his head."
And his father declined, and he said: "I knew, my son, I knew. He also will be a great nation, and he also will grow in number; but his younger brother will grow more than him, and his seed will fill the nations."

E uses "El Shaddai", which is a weird monicker for God. He also has the extraordinary "I am that I am" (more literally, "I'll be what I'll be"), which is followed by a Yahweh tack-on with an obvious seam.
Priestly (P)
Priestly can't write to save his life. He is almost surely a Levite priest, who is trying to canonize Leviticus law by attaching it to the timeless masterpieces produced by J and E. Priestly's voice is heard at the end of Exodus and throughout Leviticus.
A typical Priestly passage (Leviticus 11, vs 41-45) in my translation, available on Wikisource:

And all the vermin that infests the Earth, it is an abomination, it will not be eaten. All the walks on its torso, and all that walks on four, unto any centipede, onto all the vermin that infests the earth--- you will not eat them, because they are an abomination.
Do not abominate your souls in all the vermin that infests, and do not defile in them, and you were defiled by them. Because I am Yahweh your God, and you were blessed holy and became holy, because I am holy. And you will not defile your souls in all the vermin that crawls on the earth. Because I am Yahweh, who raises you from the land of Egypt, to be a god for you, and you became blessed holy, because I am holy.

This block is particularly repetitive, but even this example does not do justice to Priestly's cloying, unnecessary, mind numbing repetitions. Things are a "comforting smell to Yahweh" six times in a chapter, detailed grilling instructions are repeated, detail by detail, three times for three only slightly different situations. Priestly is boring, uninspired, pedantic, and generally unreadable. One of the best things about Christianity is that you can ignore nearly everything he wrote.
Priestly is also the master of stilted narrative. Here is Leviticus Chapter 10 (my translation, on Wikisource) :

And the sons of Aaron, Nadav and Avihu, each took from their sinstuff and they put fire to them, and they put incense upon it, and they sacrificed before Yawheh, on a foreign fire, which was not commanded of them. And a fire came out from before Yahweh, and consumed them, and they died before Yawheh.
And Moses said to Aaron: "That is what Yahweh spoke, saying: that with me I shall bless, and in front of all the people, I will be respected." And Aaron fell silent.
And Moses called to Mishael and Eltzaphan, the sons of 'uzi-el, Aaron's uncle, and said to them: "approach and carry your brethren from facing the holiness, to outside the camp."
And they came close, and they carried them in their cloaks, to outside the camp, as Moses spoke.

This is so stilted and badly written. Aaron's sons are immolated in his presence, and there is none of the drama of Lot running from the fire and brimstone, pleading with God to let him find shelter in a Mizar. None of the beauty and elegance of Jacob's pining for his lost son, prayed by wolves. No sign of the genius of pacing or drama of Genesis and the early half of Exodus. Their crime basically amounted to cooking communal meat on a grill different from the communal grill.
The only line of genius which can be safely attributed to Priestly is Leviticus 19:18 (in generic translation--- I went with "You loved your compatriot as yourself", but this phrase is famous.)

"And you loved your neighbor as yourself"

This is surely his, because it is embedded in a set of verses that repeat "I am Yahweh" for no good reason again and again and again.
Redactor (R)
The Redactor is whoever put the narratives together to make a whole. This is probably Priestly, the way I see it. You can see the redactor at work at several places, where verses are inserted for no reason other than the discomfort of the editor at what is being said.
consider Genesis 18, verses 16-22 in my Wikisource translation:

And the men stood from there, and they gazed towards Sodom, and Abraham walked with them, to send them off.
And Yahweh said: "I disguise from Abraham that which I am doing,
And Abraham, onwards will be a great big people, and through him all the nations of the Earth will be blessed.
Because it was known to him that which he commanded his sons and his household to do, and they kept the way of Yahweh, to make charity and justice--- leading to Yahweh bringing Abraham that which he spoke to him about.
And Yahweh said, "the cry of Sodom and Gomorrah is so loud, and their sins, so very heavy. I will descend there and see if its cries which comes to me are due to them all; and if not, I will know it."
And the men turned from there, and did go towards Sodom; and Abraham, still left standing before Yahweh.

There is an obvious break in the otherwise extraordinarily beautiful narrative, coming right after "I disguise from Abraham that which I am doing." The thing that God wishes to disguise from Abraham is the destruction of Sodom and Gommorrah, but as the angels walk toward the city, Abraham argues with God about the destruction.
Anyway, redactor didn't like that God is diguising something from Abraham, and so stuck in the completely inane two verses that follow, which simply repeat promises of God to Abraham from other passages, which are completely out of context here.
Unlike other translations, the translation above seeks to preserve the tone-deaf narrative and horrible writing style of redactor, which match the tone-deaf narrative and horrible writing style of Priestly. I don't see any reason to think they are separate authors.
There is also the issue of the "and Aaron"'s in Exodus. These read more naturally if omitted, so that God is speaking to Moses only. But the Exodus author tacks on "and Aaron" in many places, some places where it mismatches with the singular tense of the verb! This is R at work, although I don't see any reason why this isn't P.
Arguing against identifying R with P is the fact that while common authorship of writing of great genius is easy to identify, all hacks of the same era write alike.
Others
There is supposedly a D author, the Deuternomist, who continues the narration into Deuteronomy and perhaps Judges. I didn't translate those books, so I can't judge.
As for other authorial guesses, I think that the author of psalm 137 is also the author of lamentations, either in whole or in part. The word choice and the strange baby imagery is so distinctive.
Comment: @Jon Ericson: This only advantage of this answer is that it is correct, as anyone who reads the relevant cited passages can verify. I do not like to cite here, and I won't do it, because you can read the bible yourself, and verify the different documentary sources for yourself. It is important to spread the word of the Documentary Hypothesis to the deluded ones who live in the state of sin associated with the single-authorship idea.
Comment: The problem with this answer is that it isn't representative of Christianity.  Richard's [answer](http://christianity.stackexchange.com/a/2510/914) does a better job of providing a neutral viewpoint on the question.  But all is not lost!  The [Documentary Hypothesis](http://hermeneutics.stackexchange.com/questions/tagged/documentary-hypothesis) is totally on-topic at Biblical Hermeneutics.  It's even encouraged to ask and self-answer questions on StackExchange!  (I would encourage you to include references to your answers, however.)
Answer: Because of the strong tradition that Moses was the author of Genesis, the best way to answer the question is to establish whether it was likely, or possible that Moses wrote the book then, if Moses was not really the author, consider who else might have written the book.
Samuel Davidson, D.D, in An Introduction to the Old Testament, Critical, Historical, and Theological, Containing a Discussion of the Most Important Questions Belonging to the Several Books (published 1862), identified several clear lines of evidence that Genesis can only have been written long after the time of Moses. Among these:
A. Words that obviously imply that when the writer lived, the Canaanites and Perizzites had been expelled from the land -

Genesis 12:6:And Abram passed through the land unto the place of Sichem, unto the plain of Moreh. And the Canaanite was then in the land.
Genesis 13:7: And there was a strife between the herdmen of Abram's cattle and the herdmen of Lot's cattle: and the Canaanite and the Perizzite dwelled then in the land..

B. Hebron is the name almost always used in Genesis, yet the city did not get that name until Caleb changed the name of the city from Kirjatharba to Hebron, meaning that this name is posterior to Moses:

Genesis 23:2: And Sarah died in Kirjatharba; the same is Hebron in the land of Canaan: and Abraham came to mourn for Sarah, and to weep for her.
Joshua 14:14-15: Hebron therefore became the inheritance of Caleb the son of Jephunneh the Kenezite unto this day, because that he wholly followed the LORD God of Israel. And thename of Hebron before was Kirjatharba; which Arba was a great man among the Anakims. And the land had rest from war.

C. In Genesis 14:14, Abraham is said to have pursued the kings who carried away Lot his nephew, as far as Dan. But we learn from Joshua 19:47 and Judges 18:29, that the name of the place was Laish, until the Danites possessed it and called it Dan, "after the name of their father."
D. Davidson says that, because of Genesis 36:"31, the book could hardly have been written before there reigned any king over the land of Israel:

Genesis 36:31: And these are the kings that reigned in the land of Edom, before there reigned any king over the land of Israel.

E. Here Jacob is referring to the "land of the Hebrews" at a time when it was supposedly the land of the Canaanites, a mistake Moses could scarcely have made:

Genesis 40:15: For indeed I was stolen away out of the land of the Hebrews: and here also have I done nothing that they should put me into the dungeon.

This is far from the totality of evidence that Moses did not write the Book of Genesis, but it is enough to be conclusive.

In the nineteenth century, Julius Wellhausen carried out stylistic analyses, and was able to assign authors called J (the 'Yahwist') and E (the 'Elohist') to the nature and fertility stage of religion, D ('Deuteronomist') to the spiritual and ethical stage, and P ('Priestly Source') to the priestly and legal stage. At the same time, historical analysis suggested that J was the earliest source, E somewhat later, and D and P centuries later than J. We can leave out the Deuteronomist, who is considered to have had little or no input to the Book of Genesis. Subsequent scholars have challenged Wellhausen's hypothesis, but Mark S. Smith says in The Early History of God (page xxiii) that it has not been supplanted by a more persuasive model. Lester L. Grabbe, in Ancient Israel (page 44) says that many would still agree that Genesis was compiled mainly from three sources – the Yahwist (J), the Elohist (E) and the priestly writer (P).
Some modern scholars suggest modifications to Wellhausen's hypothesis, but almost all are in general agreement. The consensus is that the Yahwist wrote in around the ninth century BCE, the Elohist in the eighth century BCE but definitely before the fall of Israel in 722 BCE and the Priestly Source during or shortly after the Babylonian Exile. These writings were then redacted into more or less the form we know today, by the Redactor. The redacted compilation is definitely post-Exilic and so belongs to the period around the fifth century BCE.


Representing area as an integral independent of the coordinate systems

Question: The area/arc-length is given by an integral or the integral defines the area/arc-length is one the first things we learn in Calculus, but that is done in the Cartesian coordinates, next one moves to polar coordinates and the area is transformed/redefined by a new integral using the Jacobian. My question is : Since area and arc length are invariant of coordinate system, is there a way to define them other than in Cartesian coordinates and transform them from coordinate system to coordinate system with the help of Jacobian? In other words is there a way that area/arc-length is defined independet of coordinate system and then according to the structure of coordinate system it's integral form is reached, without tranforming between coordinate systems, but for a given coordinate system it is derived. (and without the use of Jacobian to move between coordinate systems)
Comment: http://en.wikipedia.org/wiki/Volume_form
Answer: Arc length, area and volume are geometrical concepts that make sense in a coordinate-free world. Note that Archimedes computed many interesting areas and volumes without using coordinates!  But now we have this edifice called "calculus" with its primitives, Fubini theorem, change-of-variables formula, etc. In order to make this edifice useful for computing lengths and areas we have to coordinatize our curves and surfaces. We then have to ${\it prove}$ that our intuitive idea of arc length as being the $\sup$ of the lengths of inscribed polygons, leads to the formula $L(\gamma)=\int_a^b |\dot{\bf x}(t)|dt$. This is hard work! What we have gained in this way is access to a machinery that allows to compute an unlimited number of lengths and areas in a more or less automatic way. But, alas, we shall not obtain a simple formula for the circumference of an ellipse $\ldots$