Can someone explain as simply as possible why you use OR in retrospective studies while using RR in prospective studies?

Question: I've really tried to understand why you can't use relative risk (RR) in retrospective studies but for some reason I can't understand it. Has anyone been able to convey this simply to their students?
Comment: As an exercise, try to develop an estimator for RR for retrospective studies. This must be well explained in some epidemiology text, so look there.
Comment: Let's say I look through 1000 patient charts for outcome Z. I find 100 patients have outcome Z.

I'm interested in whether gender increases the risk of outcome Z.

The prevalence in my cohort for outcome Z is 10%. 30 of 500 males have outcome Z while 70 of 500 females have outcome Z.

The risk of outcome Z for males is 30/500 = 6%, the risk for outcome Z for females is 70/500 = 14%. The RR for females is 14/6 = 2.3.

I'm obviously doing something wrong but I can't see what exactly as this makes perfect sense to me?
Answer: I have been able to explain the need for the use of the odds ratio (cross-product ratio) to estimate effect size in a case-control study to students with a simplified example of two hypothetical studies of the same (hypothetical) people—one a cohort study and the other a case-control study.
The hypothetical people are 300,000 adults.  100,000 of these adults smoke cigarettes and 200,000 don't smoke.   The distributions of age and sex in the smokers and non-smokers are identical.
Prospective Cohort Study
One researcher does a prospective cohort study of these 300,000 adults to evaluate the relationship between smoking and lung cancer.  The 100,000 smokers and 200,000 non-smokers are recruited and followed for 5 years.  Over 5 years, 1,000 lung cancers occur in smokers and 200 occur in non-smokers.  The lung cancer incidence in smokers is 0.010 (1,000/100,000) and the lung cancer incidence in non-smokers is 0.001 (200/200,000).  The true relative risk (RR) of lung cancer in smokers is:
<code>               RR = 0.010/0.001  = 10.0
</code>
Case-Control Study Based on the Same People
Another researcher does a case-control study to evaluate the relationship between smoking and lung cancer based on the same 300,000 people.  (Of course, this wouldn't happen—this is hypothetical.)  S/he identifies the 1,200 cases of lung cancer that occurred in these 300,000 people and selects 1,200 people without lung cancer as controls.  The controls are a random sample of the 298,800 people who did not develop lung cancer.  The smoking history of the cases and controls is determined.  In the 1,200 cases of lung cancer, 1,000 people smoke (0.8333) and 200 do not smoke (0.1667).  In the 1,200 controls, 400 smoke (0.3333) and 800 do not smoke (0.6667).
The data are given in the familiar case-control 2x2 table.
<code>                           Case       Control

    Smoker

    Yes                     1,000         400

    No                        200         800

    Total                   1,200        1,200
</code>
To assess the strength of the association of smoking with lung cancer, a first instinct is to calculate the ratio of the proportion of smokers in the cases to the proportion of smokers in the controls.  This is:
<code>               0.8333/0.3333 = 2.50
</code>
Very far away from the true relative risk of 10.0.
In a generic 2x2 table for data from a case-control study, the numbers of cases and controls according to exposure is as follows:
<code>                         Case      Control

  Exposed

  Yes                      A            B

  No                       C            D

</code>
The odds ratio—is calculated as the cross-product ratio:
<code>                [(A*D)]/[(B*C)]
</code>
For the hypothetical case-control study of smoking and lung cancer, the odds ratio is:
<code>                [(1,000*800)]/[(200*400)] = 10.0.
</code>
The odds ratio is very close to the relative risk—in this hypothetical example, they are exactly the same but this is not generally true.
Generalizing
Replacing the numbers in the 2 x 2 tables with proportions where p1 is the proportion exposed among cases and p2 is the proportion exposed in the controls, gives the following
<code>                          Case        Control

        Exposed

        Yes                   p1          p2

        No                 1 - p1        1- p2

</code>
The odds ratio (cross-product ratio) is:
<code>               [(p1)*(1 – p2)] / [(p2)*(1 – p1)]
</code>
The odds ratio approximates the relative risk when the incidence of the disease is "rare"—rule of thumb, less than 0.10.  Using the odds ratio from a case-control to estimate relative risk also requires that the cases and the controls both come from the same defined population.
Explanation
In a 1951 publication, Cornfield explains why the cross-product ratio from a case-control approximates the relative risk mathematically.
(https://pubmed.ncbi.nlm.nih.gov/14861651/
This is an example meant to help students being introduced to epidemiology understand better why the odds ratio needs to be used to estimate the magnitude of the association of exposure with disease in a case-control study.  No further detail will be given here.
Historical Note
Of historical interest, the use of the term—odds ratio—to describe the cross-product ratio as an estimate of relative risk did not become widespread until the early 1990's.  Until then, estimates of the relative from case-control studies were variously described as "relative risks" (without qualification), "cross-product ratios," "estimated relative risks," or "risk ratios."
Cornfield J.  A method of estimating comparative rates from clinical data; applications to cancer of the lung, breast, and cervix. J Natl Cancer Inst. 1951 Jun;11(6):1269-75. PMID: 14861651.
Comment: @Paze  Thx.  I've been using this set-up in teaching for decades and hope others might find it useful.
Comment: Hi Diana sorry for accepting your answer late, it was a wonderful write-up and very detailed. I did read it a while ago but I must not have clicked accept when I did! Thank you!


Closes Files after selecting multiple videos

Question: I have a problem with" Files "- I select 3 or more video files with the mouse, then RMB for any of the files, then select" open in Video "in the menu , then" Files " is closed. Okay!
Who can help.
I installed codecs and even Parole - I do not know what to sin. If there's anything I need to report on my system, I'm ready.
Comment: Which app are you opening with?  I do not get a crash with the native Videos app, but if I use Gnome MPV player then it crashes.
Comment: @JeremyWootten, native Videos
Comment: What version of Files are you using (latest is 4.1.3)?  What type(s) of video does this happen with?  Are the selected videos all of the same type?
Comment: @JeremyWootten, I'm using Files version 4.1.3 (io.elementary.files --version). For example, I select 3 or more files in the *.mkv format, cartoons))) Yes, all files are of the same type.
Answer: I have raised an issue regarding this at https://github.com/elementary/files/issues/856 and will push a PR to fix it shortly.


Can timbermate be used in a wet area?

Question: I'm repairing a poorly designed area behind the kitchen sink which pools with water. I've coated the existing timber with a waterproof membrane, and then plywood over the top, as the existing benchtop is pine. I've used  timbermate to fill the area, and was thinking I would seal the whole thing with a mixture of linseed oil and varnish. Will this be adequate?
Answer: You need to make sure you use marine ply when in wet areas. Covering up the old counter top with ply will cause issued in the future. I would remove the pine counter top, sand it, seal it and re-install it. When you use wood in the kitchen it is important to maintain it.
TimberMate is waterbased so isn't going to be much of a sealer. To be honest I stopped using TimberMate a long time ago. You get better results with sanding dust and glue, in this case you would use a water proof glue.
Just covering the old counter top with ply will result in the old counter rotting and causing all sorts of issues for you later.
Comment: Thanks, Brad. The counter did need removing, but as a renter, I felt this approach would be a more politically sensible thing to do - the owner wouldn't repair this at all, beyond paying some old bloke to put a layer of silicone down. This has occurred numerous times, actually making the problem worse. I did coat the old timber with a latex and fibre waterproofing sealant. The old timber will probably rot one day but by then it will be time to renew the kitchen to our taste.
Answer:
Can timbermate be used in a wet area?

Ideally, no.
From what I'm reading this remains permanently soluble in water so there are better things you might have used to fill the area! But if you make sure that no water can get to it you should be all right, which is why you want to be thorough in sealing off the area from water ingress.

was thinking I would seal the whole thing with a mixture of linseed oil and varnish.

Don't bother with the linseed oil. If you want to waterproof the surface just use the varnish. Providing a water-resistant or waterproof surface coating is one of varnish's jobs, the level of protection based to some extent on the varnish type but mainly on the thickness of the coating. Adding oil to the varnish won't improve on this, just slow the drying time.
In this case any interior oil-based varnish of reasonable quality built up into a proper surface coat should be sufficient*.
Three or more coats of full-strength varnish is usually sufficient for a good surface coating, but it won't do any harm to apply one or two more if you want to err on the side of caution. If you're thinning the varnish for application you need to increase the number of coats accordingly.
Further reading from previous Q&As:
Protecting against water damage

*But note the water will find its way below the surface given the chance, so the edge of the sink insert and the rear edge of the counter must be protected with a bead of sealer such as silicone caulk.

Can timbermate be used in a wet area?


Vertex degree on random graphs

Question: Let $p = d/n$ with $d$ constant. How do I prove that, with high probability, $G_{n,p}$ contains a vertex of degree at least $(\log n)^{1/2}$,
where $G_{n,p}$ is a graph with $n$ vertices and the number of edges is a binomial random variable with the parameters?
Comment: The distribution of one degree is binomial, which in this case is very close to a Poisson distribution with mean $d$.  Moreover, the degrees of two vertices are almost independent. The second moment method will give you what you want. This sort of thing is well worked out, probably it is a special case of something in Chapter 3 of Bollobás' book "Random Graphs".
Comment: Can you use the central limit theorem to estimate the probability that a particular vertex has degree at least $(\log n)^{½}$?
Comment: It would help motivate to say where the question comes from, and why the large amount of existing research on Erdos-Renyi graphs did not give you an answer.
Comment: I tried to do it and got confused.. I would like instructions on how to use the second moment here ?
Answer: Just an amateur answer, I would assume there's a paper or known approach out there from experts.
I would partition the vertices into equal sets $U,V$ and delete edges to make it a bipartite graph. It suffices to show that there exists a vertex in $U$ with enough edges after the deletions.
Now the degrees of vertices in $U$ are independent, so the probability they all have degree less than some given $t$ is the product of the probabilities. And we can bound
\begin{align}
  \Pr[\text{degree}(v) < t] &= 1 -\Pr[\text{degree}(v) \geq t]  \\
 &\leq 1 - \Pr[\text{degree}(v) = t].
\end{align}
(You could try for a more sophisticated bound, but I don't think it will help much when the mean degree is a constant $d$ and $t = \omega(1)$.)
Then,
\begin{align}
 \Pr[\text{degree}(v) = t]
 &=    {n/2 \choose t} p^t (1-p)^{n/2-t}  \\
 &\geq \left(\frac{n}{2t}\right)^t p^t (1-p)^{n/2-t}  \\
 &=     \left( \frac{d}{2t} \right)^t (1-p)^{n/2-t}  \\
 &\approx \left( \frac{d}{2t} \right)^t e^{-np/2} \\
 &=       \left( \frac{d}{2t} \right)^t e^{-d/2} .
\end{align}
(This is essentially the Poisson approximation; there may be better ways, and note you'll have to rigorously handle the $\approx$ step.)
For $t = o(\ln(n)/\ln(\ln(n)))$, I believe $(2t/d)^t = o(n)$. It must be true for $t = \sqrt{\ln(n)}$.
So
\begin{align}
  &\Pr[\text{all vertices in $U$ have degree $< t$}] \\
  &\leq    (1 - \Pr[\text{degree}(v) = t])^{n/2} \\
  &\approx (1 - (d/(2t))^t e^{-d/2})^{n/2}  \\
  &\leq    \exp\left( - \frac{n (d/(2t))^t e^{-d/2}}{2} \right) \\
  &=       \exp\left( - \omega(1) \right).
\end{align}

Vertex degree on random graphs


How many solana transaction confirmations are enough to declare a transaction as finalized before it hits 31 and actually finalizes itself?

Question: So i'm messing around with transactions and want to make sure that it goes through before continuing so that i dont end up losing solana as if this were a peer to peer transaction. Waiting for a tx to hit 31 confirmations takes too long and I want to speed it up, so whats a good amt of confirmations for me to declare a transaction as finalized myself to speed up the whole process a tad bit? Thanks.
Comment: this can't really be answered in a general way, it's application specific
Answer: Solana offers three different commitment levels, finalized, confirmed and processed, as described here.
A commitment level of confirmed is usually considered sufficient unless your existence depends on it. It is usually quite fast, as 1 - 3 seconds or so.
Solana doesn't work with the "number of confirmations" scheme that is used in Ethereum with PoW. The commitment levels are based whether a supermajority of validators has confirmed the transaction (finalized) or includes votes from gossip (inter-validator communication) and replay (confirmed). Therefore, the time to confirmed and time to finalized can vary.


Bieber Roast Jokes

Question: In the Justin Bieber Roast on Comedy Central, Justin remarks that Natasha Legero did not shoot out ping-pong balls like snoop promised. Can someone explain the significance of this? I don't understand the reference.
Comment: Wow, I'm not sure how to answer this one in a family friendly way.
Answer: In certain establishments, notably in those areas with a reputation for bawdy licentiousness you can go to see live sex shows where a female performer will expel ping-pong balls from an intimate body part.
Justin Bieber was presumably claiming that he was promised such a performance (from Natasha Legero) in return for attending his roast, something he might not have otherwise done given how little he would enjoy it.
The joke itself is a variant on the classic "You said there would be x", "yeah, I lied" formula.
Answer: Roasts are for people to insult each other...
The joke is that Natasha is such a dirty, filthy woman, that she is able to do that. Also there is a possibilty that she did  it FOR Snoop at one point.
Also, if you're even in Japan. Check that, or the banana lady out...

Bieber Roast Jokes


Two asp:content in web content form

Question: Whenever I create a new Web Content Form in asp.net and select a master page. I get two asp:content controls. If I delete the first one the page still works fine.
Is this a bug or a functionality
Answer: The master page likely has two placeholder controls. When you select a master page it will give you the template for both, but you are not required to use them both.
If you wanted to delete one, it would be the same as basically leaving the content control empty.
Answer: You're master page has 2 content sections.
Deleting one or more from the content page will just make that part of the page empty, which is why there is no error / exception thrown.
If you are not going to use it, might as well get rid of it in your MasterPage file, save that processing power of your server.

Two asp:content in web content form


Does RMS value of AC signal depend on frequency?

Question: The formula for voltage RMS is usually given as the peak value divided by the square root of 2. I feel like maybe I am missing something: how can two AC signals with same amplitude but different frequencies have the same RMS value?
Comment: *how can two AC signals with same amplitude but different frequencies have the same RMS value?*  Yes, you're missing something.  With questions like this, it's hard to figure out *what* you're missing because you don't say why you expect there to be a difference.  For two sinusoidal signals of the same peak amplitude, how could they have different RMS values?  (They can't, assuming you average over a whole number of periods for both of them, i.e. the long-term average.  Are you thinking about time-scales shorter than the period?  Or something else?)
Comment: Does the peak value change with frequency? Does the value of root 2 change with frequency? But I understood RMS meant square, then mean then root...
Comment: @AbdelAleem  When you mention "the mathematical formula for RMS"  what exactly do you mean?
Comment: @SolarMike assuming the peak values remain static for both signals but frequency is different. Do they have the same RMS value?
Comment: @PeterCordes if you sample the mean squares over 1 period for example (for each AC signal respectively). I was thinking mostly about the mathematical formula for RMS which includes frequency/period ...
Answer: You can think of the RMS voltage as related to the power that the voltage can deliver into a resistive load.
A 240VAC 50Hz mains can supply just as much power as a 240VAC 60Hz (or 400Hz) mains to a resistive load.
The \$\sqrt{2}\$ factor is specifically for a sinusoidal waveform. A waveform that is not sinusoidal will, in general, have a different factor.
But even if the waveform is different, the RMS value of a periodic signal is independent of the frequency when it is calculated over an integral number of cycles. The power supplied to a resistive load varies throughout the cycle, of course, and the energy delivered to the load per cycle is less at higher frequencies, but when you average the energy per unit time (which is power) you get the same number regardless of frequency, all other things being equal.
Here is a simulation of sine waves feeding 1Ω resistors. One is 60Hz and one is 120Hz. Both voltages are 10V peak sine waves (~7.071V RMS). The top pane shows the voltages plotted over 100ms. The bottom pane shows the power delivered to the resistors over time.

In both cases the power averaged over an integral number of cycles (in this case, I used 100ms) is exactly 50W, which is \$V^2/R\$ if you use the RMS voltage for V.
Answer: For any periodic signal, the RMS voltage is independent of frequency. The formula that you are referring to is a particular case when the signal in question is sinusoidal.
To understand the reason two AC signals with different frequencies can have the same RMS value, we have to look at the definition of "RMS" or Root-Mean-Square. This definition literally means to take the squareROOT of the MEAN of the instantaneous voltage values SQUARED. There is no frequency terms involved in this definition; only the square of the instantaneous voltage values integrated across one period. An identical signal only differing by frequency would have a one-to-one correspondence of instantaneous squared voltage values. The only difference being the period is shorter for the faster frequency signal. The formula looks like this: SQRT[(MEAN(integral(V^2(t)))] integrated over one period, or t=0 to t=2*pi
Comment: It doesn't have to be periodic. RMS is a fine measure of random noise.
Comment: @JohnDoty Agreed. But based on the context of the question, I was trying to keep the answer simple. Comparing noise sources is much more esoteric than comparing sinusoidals.
Answer:
Does RMS value of AC signal depend on frequency?

No, but the time taken to calculate RMS has to be longer for a lower frequency for it to be an effective comparison.

how can two AC signals with same amplitude but different frequencies
have the same RMS value?

A 1 volt p-p sinewave of 1 kHz has exactly the same RMS value as it does when 2 kHz.
Answer: In simplistic terms, the RMS AC voltage is equivalent to the DC voltage value that produces the same amount of power dissipation in a resistor.
In mathematical terms:
$$ V_{RMS} = \sqrt{{1 \over {\theta_2-\theta_1}} \int_{\theta_1}^{\theta_2} \left(f(x) \right)^2\;dx} $$
For \$f(x) = sin(x)\$, if \$ \theta_2 - \theta_1\$ is a integer multiple of \$\pi\$ (half cycle) the RMS voltage will be \$1 \over \sqrt{2}\$. Notice that frequency isn't part of the calculation, but angle is.
If the data is sampled:
$$ V_{RMS} = \sqrt{{1 \over n} \sum_{i=1}^{n}x_i^2} $$
Answer: There are some rigorous mathematically-based answers here; I'll offer my intuitive answer.
Periodic signals spend more time at every voltage as they get slower; the extension of dwell time cancels out the frequency change when calculating a mean. For RMS, which is a special kind of mean, frequency is irrelevant, as long as you perform the measurement for a long enough time to gather data (either exactly one half of a cycle or so many cycles that also including a fractional part of an extra cycle isn't significant).
This is a theoretical consideration, however; don't confuse this with real-world quantities such as reactive or apparent power, which are very much frequency-dependent. While frequency "doesn't matter" to RMS, it does matter in AC circuits for other measurements or calculations. The fact that RMS remains the same regardless of frequency does not mean that frequency doesn't change power delivery or dissipation.
Another "gotcha" is that depending upon the implementation of a meter, it may be affected by waveform shape and frequency, so you've got to understand how your equipment works and if it's applicable to the signal you're measuring.


Is there an omnibus for the entire Blackest Night and Brightest Day story arcs?

Question: I really wanted to read all the comics that dealt with this story arc (and I hear ALL of them did) and I was wondering if there was an omnibus available for me to buy, or if there isnt, which specifically are the issues that were included in this story?
Answer: It looks like there isn't one omnibus available, and the larger Blackest Night event covered a nearly unwieldy amount of issues. Brightest Day is a similar story.
That being said, both stories have been collected in a ton of collections. The titular collections contain the issues of the main eponymous series, while the rest cover spin-offs.
Blackest Night

Blackest Night
Blackest Night: Tales of the Corps
Blackest Night: Black Lantern Corps vol 1
Blackest Night: Black Lantern Corps vol 2
Blackest Night: Rise of the Black Lanterns
Green Lantern vol 7: Blackest Night
Green Lantern Corps vol 6: Blackest Night

Brightest Day

Brightest Day vol 1
Brightest Day vol 2
Brightest Day vol 3
Green Lantern Corps vol 8: Brightest Day - The Weaponer
Justice League: Generation Lost vol 1
Justice League: Generation Lost vol 2
Titans vol 4: Villains For Hire
Answer: They are releasing a brightest day omnibus in September. 2014
Comment: Can you back this up with a quote or link?
Answer: It looks like this is the Brightest Day Omnibus.
https://www.amazon.com/Brightest-Day-Omnibus-Geoff-Johns/dp/1401245978/
Comment: Could you show how/why you think this is the answer? We don't like link answers, it is better to quote the relevant information from the link, then use the actual link as a source.
Comment: I was trying to add the link to the comment from Brett White and Zod/Valorum, but I couldn't add the link as a reply to those comments. That's why I commented just the link.


Securing the cable chain on a CNC gantry

Question: I have laser cut the ends of a bicycle brake cable cable chain platform on a CNC I am building. I have looped the bicycle brake cables around one end and tucked the end of the cable through the loop. There is enough friction that the cables stay reasonably taught, though I suspect during normal use, this would sag. Does anyone have a suggestion about how to secure the ends to prevent slipping? I thought I might solder the cable together, but thought a mechanical option would be better, preferably one that would allow me to easily detach the cables should one of the wood brackets break.
Answer: One option you have is to use a product known as a split bolt. It's commonly used to join ground wire to an existing ground lead without having to break or cut the existing lead:

I've used them to secure 1/8" diameter steel cable for various purposes. Inexpensive and common in big-box hardware stores. So many links returned from my search making it impractical to suggest any specific source.
Comment: This is the type of thing I was looking for, though the particular configuration of this linked image looks like a hassle to deal with multiple split bolts next to each other. The answer I posted below looks like it will be easier to clamp down on the wire in a tight space while maintaining contact between the wood bracket and the stop.
Answer: Seems like you could use a cable tensioner like they use in cabled railings.
The ones on amazon seem pricey but I'm sure there's a plastic version you could get in the hardware store.
This Old House shows their usage in the railing system. https://www.youtube.com/watch?v=kNFalmwg3nY
Answer: I think I have found the ticket. A cable stop that is 6mm in diameter should just barely fit the clearance between holes. If I alternate the orientation of the bolt on top/bottom, I should be able to tighten with a socket too. Blind dumb luck on the engineering tolerances there. $15.50 with shipping for 5.


What stops Chinese companies from printing "Made in US" on their products?

Question: I was wondering if manufacturers of any country are legally bound to print the true origin of the product while exporting to other country? If yes, who makes sure they are printing the real origin of the product?
Comment: It's just the market. People won't buy Chinese stuff labelled "Made in US".
Comment: @Greendrake how would people know that the mislabeled goods were in fact made in China?
Comment: @phoog A customer who really wants to verify the origin can outrule "Made in US" simply by calling the manufacturer and talking to them about how their US factory goes. No contact details on the packaging? Well, in that case no further evidence needed.
Comment: @Greendrake surely if they were sufficiently interested in misleading people about the origin of their goods they could make up a story about their US factory.
Comment: Slightly relevant: the old story about products from Usa, Japan being exported with "MADE IN USA" labels (sadly an urban legend): https://www.snopes.com/business/genius/usa.asp
Answer: The same things that stop people robbing banks ... it's illegal
Start with consumer protection law that are common in almost any country.
For example, the Australian Competition and Consumer Commission is the "police" at a national level for the Competition and Consumer Act 2010. Each state has "mirror" legislation that cover areas where Federal power doesn't reach due to constitutional limitations and they have their own "police".
With respect to Misleading and Deceptive Conduct they say:

It is illegal for a business to engage in conduct that misleads or deceives or is likely to mislead or deceive consumers or other businesses. This law applies even if you did not intend to mislead or deceive anyone or no one has suffered any loss or damage as a result of your conduct.

And with respect to False and Misleading statements:

It is illegal for a business to make statements that are incorrect or likely to create a false impression. This includes advertisements or statements in any media (print, radio, television, social media and online) or on product packaging, and any statement made by a person representing your business.

And, specifically about Country of Origin claims:

If you choose to make a country of origin claim, or are legally required to do so, it must be clear, accurate and truthful.
How to safely make a country of origin claim
It's up to individual businesses to work out what type of origin claim they can make about their products. To provide certainty to businesses, the ACL sets out four situations where you can safely make a country of origin claim without it raising concerns under the law. These are referred to as 'safe harbour defences'.
The safe harbours cover claims that goods:

were grown in a particular country
are the produce of a particular country
were made or manufactured in, or otherwise originated in, a particular country
carry a mark specified in an information standard relating to country of origin.

If a business satisfies the criteria for a safe harbour defence they will have an automatic defence against an allegation that they have breached the relevant section of the ACL insofar as the claim concerns a country of origin.
Failure to satisfy the requirements of a safe harbour doesn't mean that a business is unable to make that particular country of origin claim. A business may still make the claim provided they are confident an ordinary and reasonable consumer wouldn't consider it to be false, misleading or deceptive.

Sanctions for breach:

Consumers—or other businesses—that believe they have been misled by a business and suffered damages as a result can pursue
  the party who has breached the law for damages.
Just as you must adhere to the ACL, so must your competitors. As a business, you also have a right to take action against a
  competitor if you feel you have suffered loss or damage as a result of them breaching the ACL.
The ACCC, the state and territory consumer protection agencies and any other individual or group can take legal action against
  businesses for contraventions of the ACL.
The ACCC's enforcement powers are extensive—for some contraventions it can seek remedies such as criminal or civil pecuniary
  penalties up to $1.1 million for companies and $220 000 for individuals, infringement notice penalties of up to $108 000 for
  publicly listed companies, $10 800 for corporations and up to $2160 for individuals, disqualification orders, injunctions to prevent
  ongoing conduct and corrective advertising orders.
In determining whether to take action, the ACCC gives enforcement priority to matters that demonstrate one or more of a range
  of factors such as whether the conduct is of significant public interest or concern, is conduct resulting in a substantial consumer
  (including small business) detriment, is unconscionable conduct, particularly involving large national companies or traders, or is
  conduct demonstrating a blatant disregard for the law.
While the ACCC may not take action on all matters, many state or territory agencies are well placed to address issues relating
  to local advertising and selling practices. For small businesses, the Australian Small Business Commissioner or the state-based
  Small Business Commissioners (in some states) may be able to assist with a dispute or problem.

What stops Chinese companies from printing “Made in US” on their products?


Does LRCK have to oscillate in an I2S system?

Question: I'm working on a audio function generator using the PCM 1795 DAC. I only need a single output channel for my design. Can I just pull LRCK low or high permanently for the sake of maintaining design simplicity? Much thanks.
Answer: LRCK cycling is required to indicate the framing of the data even with only one channel.
Effectively the LRCK indicates the position of the MSB of a word (in some styles offset by one bit position).
Answer: No, you must use LRCK. It is used to identify the beginning of the frame, as well as separate the left and right audio samples. See page 19 of the data sheet1


Which video codec would be most suitable to displaying text?

Question: I am making a video of a CMS in action. Any ideas which codec might be a good idea?
Ben
Answer: Check the MS codec offerings - there is one actually optimized for screen playback. As it is a DirectShow codec, adobe should work with it. Flash is another matter, but then tehre you are limtied anyway.
http://www.microsoft.com/windows/windowsmedia/forpros/codecs/video.aspx
has all the normal codecs. Scroll a little down for the Windows Media Video 9 Screen.
I used that for a couple of demonstrations and that worked very nicely - especially as it goes to a lossless thing when not a lot changes, which is VERY typical for demos that do not include games (as most of the screen is actually static).
Playback works on every windows machine.
If you need something platform independant, you basically are out of luck. Nothing there that is screen optimized.
Comment: It's going to get Flashified and put on a website, like all the pretty CS5 videos on the Adobe site. So I'm really looking for a wey to get Premiere to spit out a decent enough file so that Flash can do its worst and it won't look too tragic.
Answer: There are lots of screen recording software such as CamStudio which generate Flash videos and take care of the exact formats they are using.


Changing Pivot Point in Java3D

Question: I've imported some 3d models in java3D and I want to change the pivot point of my model from the origin to a specific point!
Please don't say to translate to origin, rotate and then translate back
I want to know the exact way .
Answer: This helped me. The idea of translation is good, actually, do it like follows:
Create a TransformGroup "tg" for example containing the node you would like to rotate and/or translate.
Be sure that you translate it to the point you want to be your pivot point.
Then, create a new TransformGroup containing tg, and rotate it.
Translate back then (translate with the same vector*(-1)).
Rotation around a specific point (eg, rotate around 0,0,0)
This helped me
Answer: If I understand what you mean, you should traverse the scene graph produced by the model loader, find any GeometryArrays in it, and translate all the coordinates in the GeometryArrays (this is no simple task -- coordinates can be stored in a number of ways).  That way a simple rotation transform would rotate around a different pivot point than before.

Changing Pivot Point in Java3D


How does positive feedback generates ac waveforms in an opamp?

Question: How can an ac oscillation be obtained by using an opamp and some components and what is the working principle behind?
Comment: When on stage, if you hold the microphone to close to a speaker. (feedback) That's the principle.
Comment: sounds good example but could u expound on it a bit more why mic causes this?
Comment: A multitude of frequency's go in the mic and are amplified. One of those frequencies re-enters the mic in phase, and goes around and around getting more amplification with each round trip. Eventually being heard out the speaker. Moving the mic closer will select a different frequency that is in phase, so the pitch changes. The pitch jumps to the next in phase strong node.
Comment: One oscillator design, furnishes positive feedback of some of all output frequencies, and negative feedback of all output frequencies except for filtering out the desired frequency. So unwanted frequencies and distortion cancel out, only the differences are enforced (desired frequency). This greatly reduces distortion in the final output. "Twin-T" is an low frequency example. It's a different way of viewing an oscillator.
Answer: An op-amp oscillator can be two types usually: -

A squarewave relaxation oscillator when the op-amp is used as a schmitt trigger
A sinewave oscillator where the op-amp is used as a linear amplifier

I'm assuming that the question relates to the 2nd type of oscillator.
To generate a sinewave you need positive feedback to the input. Positive feedback means feeding back a signal that is exactly in phase i.e. op-amp output and op-amp input are in phase exactly. If they are not in phase exactly a sustained oscillation frequency is not achieved.
There are then two more criteria to be met for a sustained sinewave oscillation: -

The feedback has to produce a non-zero degrees phase change for all frequencies except one.
The feedback has to control the sinewave amplitude to prevent the op-amp from clipping i.e. it has to produce the coherent sinwave at just the right amplitude.

It's easy with a squarewave oscillator - you don't mind the op-amp saturating because it won't affect the shape of the squarewave but for a sinewave it can be a little tricky. The circuitry that produces only one coherent frequency is usually a phase shifting network made from resistors and capacitors i.e. it is a filter. Another type of phase shifting network has a specific name - a wein bridge oscillator. This also uses resistors and capacitors.
What ever method is chosen, the result is the same - the signal that gets fed back exactly (and coherently) reinforces the signal at the input to the op-amp amplifier.
Amplitude control is usually based around a circuit element that behaves like a voltage dependent resistor (VDR); the output signal is converted to a dc level representing the amplitude and this is used to reduce the op-amp amplifier's gain via the VDR - if the signal gets too big the gain is reduced thus, the amplitude is kept reasonably constant and free from distortion.
Comment: is there a reason for the down vote? I mean it's not a big deal because I'll just delete the answer should there be no further voting so a down vote without an explanation is pretty futile really.
Answer: The principle is that it takes SO LONG for the signal to go through the circuit, that by the time it comes out and is looped around to the start again, it is exactly in-phase, exactly one-cycle-behind, exactly the input signal required to make an identical output signal.
Of course if the output is any bigger than the input was last time around, the signal will grow.  If the output is any smaller than the input was last time around, the signal will drop.
So either the circuit has to be EXACTLY balanced just right so that the signal doesn't grow or shrink (almost impossible), or the circuit has to be more-or-less non-linear: if flattens out signals which are too big, it amplifies signals which are too small.
If the circuit is MORE linear, you get an almost-sine-wave going through the circuit. (Sinasoids are the eigenfunctions of linear systems). If the circuit is LESS linear, you get a square wave going through the system.
Since periodic signals are repetitive, the same delay can match any harmonic frequency. So oscillator circuits are also designed to block/diminish signals at other frequencies. Sometimes this happens more-or-less automatically, because the frequency response of the amplifier rolls-off at higher frequencies. Often the reason the frequency reponse of the amplifer rolls-off at higher frequencies is to prevent unwanted oscillation.
Either way, you can then feed the signal into another filter or another non-linear system, to get a sine wave from a square wave, or a square wave from a sine wave.
To get different frequencies, you adjust the delay, the time it takes a signal to go through and around the circuit. Any random noise at the input will start oscillation, and the oscillation will be at the delay frequency (because that's how long it takes to go around and through the circuit).
It's common to think of electronics as being immediate - you turn the switch on, the light comes on - but that's simply not true, as shown by circuits like this.


Does a comma indicate the conjunction "and"?

Question: Does a comma mean "and"  when used to separate items in a list?
Comment: or, in other words........ no
Comment: But if you say "Do you want eggs, chips, sausage and beans?", then the comma does imply "and".  In such lists, the comma is equivalent to either the "and" or "or" that separates the last two things in the list.
Comment: If I ask you "Do you want tea, coffee, juice or hot chocolate?" do you assume your choices are (tea and coffee and juice) or (hot chocolate)? If not, why do you assume the comma means _and_?
Comment: No-one mention an Oxford Comma, whatever you do!
Comment: I second Simon B's answer, and will add this: commas between adjectives do imply the word "and" unless "or" is stated explicitly, e.g. "the fat, jolly, red-cheeked elf" (the elf is fat and jolly and red-cheeked).
Comment: @WilliamBloom that's not a list.
Answer: When used in a list, it means that you are about to state a further element of the list.
The conjunction and, or or nor also separate elements of the list whether following a comma or not.
It's reasonable enough to say that the comma is a bit like another instance of whatever that conjunction is (and, or, nor).
However, saying "a comma indicates the conjunction 'and'" implies that it would be entirely equivalent if we repeated the conjunction, and even after correcting for the fact that it could be or or nor, this isn't quite correct.
Generally we don't include such extra conjunctions, but we sometimes do for effect, which is called polysyndeton. (A list that deliberately has no conjunction at all is in contrast, asyndeton). Polysyndeton can give a more poetic rhythm, or convey a variety of impressions from solemn to exuberant, or a sense of being overwhelmed by the number of items in the list. Consider:

… So we'll live,
And pray, and sing, and tell old tales, and laugh
At gilded butterflies, and hear poor rogues
Talk of court news; — Shakespare, "King Lear" Act V scene iii.

Here the inclusion of the repeated ands helps maintain the sense of a list despite the elements being so heterogeneous. In comparison "…we'll live, pray, sing, tell old tales, laugh at gilded butterflies, hear poor rogues talk of court news" loses the sense of it being a list at all, because of the difference between the elements.

But there is neither East nor West, Border, nor Breed, nor Birth,
When two strong men stand face to face, though they come from the ends of the earth! — Kipling, "The Ballad of East and West".

Here the inclusion of the additional nor serves three functions.

It stamps out the rhythm of the poem.

It helps marks the list as being of two parts; that {East, West} are one list and {Border, Breed, Birth} another list, though those two lists are then combined into another list.

It helps convey the sense of there being many factors considered (and in this case then dismissed).

Again, even if we ignore the matter of rhythm as not being about meaning, "there is neither East, West, Border, Breed, nor Birth" does not convey the same thing. In particular there's more of a sense of the list being small and exhaustive rather than large and inclusive of other elements not yet included.

In looking at these two cases where the more unusual decision of repeating the conjunction was used, and seeing how the have a different effect than the usual use of several commas and a single conjunction, we can see that it's not quite correct to say that the comma "means and" here. It's meaning is close, but not quite the same.
Comment: so.. yes or no?
Comment: @caub If you want a yes or no answer, flip a coin.
Comment: Heh,someone just down-voted me because I refused to give @caub an inadequate answer.


Is 5 years of professional experience bad for a future career in academia?

Question: I am a current master student (my field is earth sciences). Some time ago, I was sure that I should apply for a PhD right after I graduate with a master's degree. However, now I am thinking about taking a gap and working for about 5 years prior to my PhD. Will this professional experience look good or rather bad in my CV if I plan to apply for research-based PhD programs and pursue my future career in academia? Thank you.
Answer: If the job you take is research based then it could help rather than hurt. But one issue, in some places, is that letters of recommendation from academics (primarily) are very important. The US is like that. So, explore the requirements for application and keep in touch with former professors if that is an issue.
Letters in general need to confidently predict your likelihood of success in a doctoral program. Those with doctorates (academics or other researchers) who know you and your work well are in a position to do that. Others not so much.
Something else to think about is whether living for a few years on a much reduced income will be feasible for you at that time. Other things may happen in your life that make you depend on that income.

Note that "research based" can be subtle. Much (most?) of the "research" at companies (as opposed to research labs) is product based. That isn't the same thing and has much less value in many cases, though I don't know what product based earth science would look like. By "research" I intend extending what is known rather than extending what is useful.
Answer: If the job will benefit your application will depend on the type of job. If the job is say, as a lab technician and you are thinking of a PhD in Mol Bio, or if the job is an as an engineer if you are thinking of a PhD in engineering, etc. Otherwise, as others have pointed out, the main issue might be that your letters of reference from professors will be dated.
But regardless, I am of the opinion that taking a break between degrees is a great idea. I took a 6-year break between my BS and PhD and I think it helped me a lot, especially in terms of managing relationships with coworkers and supervisor, project management, etc. It is also my observation that older grad students do better than those fresh out of college, all other things being equal.
Your experience outside of academia will also give you perspective. Academics complain a lot (myself, I log about 5 complaints per hour, 10 per hour on Mondays), but after spending 5 years outside of academia, you will also appreciate how good academics have it.


Indexing PDF files without java

Question: Is there a way to index PDF files so that they can be searched (the text inside the PDF) without using java? Our host refuses any software that requires java, and every module I've found has required it. Since the host refuses anything that uses java, I haven't been able to find a solution that works.
Comment: Are you using [Search API attachments](https://www.drupal.org/project/search_api_attachments) for the integration? If so then no, there's no built-in support for a PHP extractor (if such a thing even exists out in the wild). It does support alternatives to Java, though (pdftotext, python, golang, etc). If your backend is Solr, there's also a built-in extractor which can be used, if it's enabled
Comment: We haven't chosen the back-end for it since we were still choosing which modules to use. Every time I think I have one, I find that something that is required uses java and I'm right back to the beginning. So, I'm fairly open with regards to what to use.
Answer: In theory, you should be able to use a combination of the following modules to index PDF content, without any external dependencies:

Search API (and its database backend sub-module)
Search API Attachments
Search API Attachments PHP

The third module needs a patch to make it compatible with Drupal 10. If you don't already have it in your composer.json, you'll need to install and allow the Drupal Lenient composer plugin to require the module without errors.
There are some simple instructions on setting up the attachments module here, you would choose the "PHP" extractor instead of "Solr".
It's worth bearing in mind that more advanced search solutions aren't usually based on PHP/SQL, for performance reasons. If you're indexing a lot of documents, you might see some degradation. If that happens you'll probably need to consider implementing/purchasing a more purpose-built solution (like a Solr instance).

Indexing PDF files without java


How to convert a string to fragment file name

Question: I am trying to take the contents of a string that I get from another part of the program, and convert it into the name of one of my java fragment files.
That name will be used to pull up that specific fragment.
For instance, my file name is colors, and the string has the value colors.
I know that it is getting the correct file names, but I just don't know how to convert it to the right type needed for a fragmetn class name. I tried using Class.forName() method but it is errored out with "Cannot Resolve Symbol (forName)" and it fails to compile.
Fragment fragment = null;
String selectedLocation = mMenu.get(position).getLocation();
fragment = new Class.forName(selectedLocation);

Comment: https://stackoverflow.com/a/39770302/5791681
Answer: Retrieve like below
 Fragment fragment = null;
 String selectedLocation =
 mMenu.get(position).getLocation();
 //fragment = new Class.forName(selectedLocation);
 fragment = (Fragment) Class.forName(selectedLocation).getConstructor().newInstance();


Replacing save button with submit for approval in the edit page

Question: I want to replace the save button with submit for approval in an edit page of record. So that every time a user tries to edit the record then it won't be saved right away rather it will be submitted for approval. Btw i am using standard salesforce page.
Comment: If you want to *save* their edits in a deferred way, and only *commit* them to the record once they are approved, then this is actually a fairly complicated request. I think you would need a separate approval object and a trigger. Perhaps someone will have a simpler recommendation, though.
Answer: You can't replace the "Save" button like that. If you absolutely need something that automatically sends a record for approval, I recommend you write a trigger that manually does that on any save.
If you follow the sample in this link you will be able to see how it's done.
This snippet will prove particularly useful
<code>    // Create an approval request for the object
    Approval.ProcessSubmitRequest req1 = new Approval.ProcessSubmitRequest();
    req1.setComments('Submitting request for approval.');
    req1.setObjectId(*<Object ID>*);

    // Submit on behalf of a specific submitter
    req1.setSubmitterId(*<User Id>*);

    // Submit the record to specific process and skip the criteria evaluation
    req1.setProcessDefinitionNameOrId('*<ProcessName>*');
    req1.setSkipEntryCriteria(true);

    // Submit the approval request for the object
    Approval.ProcessResult result = Approval.process(req1);
</code>
Comment: Yeah, the point is just that links can break, so that content could be lost entirely. Especially with SF documentation it seems.
Comment: Hey Sebastian, I know you know better than to post a Link Only Answer. :) Can you include some content?
Comment: It's pure code.... didn't think it was completely relevant.... but I can eat my own dog poo and do that. :D
Comment: I know, I know... I should've known better and got lazy. :)


If type of the value cannot be analyzed by looking into the bits, how does the machine know how the value should be manipulated?

Question: If type of the value cannot be analyzed or found out by looking into the bits(As written in books I have referred), how does the machine know how the value should be manipulated?
Comment: Everything needs to have some type in C++. That's how.
Comment: @Mgetz That's not what undefined behavior means. What you are talking about is called "implementation-defined", and it's still irrelevant to the question.
Comment: @Mgetz This has nothing to do with undefined behavior.
Comment: Eventually, deep enough, everything is just bit manipulation. *How* the bits are manipulated is controlled by the *type* of the value.
Comment: +1: This is actually not an unfair question, if you're not familiar with the way compilers work.
Answer: C and C++ are statically typed, meaning that types are a compile-time concept. The compiler generates code to manipulate the bits in a manner appropriate to the type; the machine executes that code, and doesn't need to know anything about the type.
Comment: As a side note, I would like to add that it is possible to manipulate a set of bits with meaning in both cases, such as the Fast Inverse square root calculation used in Quake 3: http://en.wikipedia.org/wiki/Fast_inverse_square_root .  To summarize, a 32-bit float is manipulated as an integer for a few instructions because it was a faster method to get an approximate result.
Answer: The compiler knows the type of every variable because you must declare each type. So the compiler generates the appropriate instructions for dealing with a variable of any particular type.
Answer: The machine does not know: it's the compiler who knows. The same code for different types won't generate the same machine code.
Answer: The C or C++ compiler knows.  So it knows to generate a MULTIPLY REAL vs a MULTIPLY UNSIGNED INTEGER vs. a MULTIPLY SIGNED INTEGER assembly instruction.  Sure, at our level, it's all just a <code>*</code>, but that's the primary objective of a compiler - to generate the assembly code necessary to yield our desired result.
Answer: It is known to the compiler at compile time. When the program runs then this area of memory is manipulated according to the compiled code. This is why C++ and C# force defining types in source code.


Protecting Test Equipment During an ESD Test

Question: I am planning to run an ESD test on a product running traffic to some test equipment over gigabit ethernet and some other signaling interfaces (RS-232, USB, etc.) How do I decouple the ESD spikes from my test equipment so that I don't accidentally induce a failure in the test equipment instead of the device under test?
Answer: The conventional wisdom is to not connect the interfaces to expensive test equipment during the ESD tests!
Best strategy is to have your product equipped with loop back capability and establish product functionality based upon the success of that loopback working throughout the test. (My experience is that some classes of tests proscribed by agency requirements is that the equipment remain operational through the tests). Obviously the loop back has to happen at the end of the cables since typical application cables are must be installed on all ports during such tests.
If certain test fixtures are required make them with a robust design so that they have adequate protections. And bring a spare test set along to the testing lab so that if the fixture fails in the ESD test that you do not waste the test day and are able to continue to the other classes of tests on your product.
Comment: Yeah -- zapping box A can break the stuff in box B.  Quite a nuisance.
Comment: Argh, yeah, that was what I figured.  :-) I'm going to write the test plan showing the cable assemblies disconnected from the test equipment and see if the customer accepts it.
Comment: @JasonASoares - It is more then what the customer will accept. You have to deal with what the test engineers at the agency testing lab indicate what is required in order to pass the ESD tests. My past experience is that the equipment has to be shown to remain functional throughout the ESD events. There is obviously some leeway in defining "remaining functional" but substantial operational behavior needed to be demonstrated. One product I had to test was a video conferencing system I designed. The testing lab found it acceptable to define remaining functional as being a test (continued)
Comment: (continued from above) mode video call between two of out units wired up back to back via a local ISDN call loop back. If the "call" dropped it was considered a failure. If the user interface screen on the video monitor stopped working it was considered a failure.


Advance Microeconomics

Question: Show that u=a+bM-yM^2 represents a risk averter's utility function who is interested only in the mean and the variance of the state distribution of Income M.  Can anybody send me the full solution. thanx
Comment: can anybody send me the full solution? thanx
Answer: I assume that the agent is an expected utility maximizer with Bernoulli index $u$, where $b$ and $y$ are fixed constants. Then, just take expectations of $u$ and try to write the right-hand side as function of the mean and variance of $M$.
For the risk aversion part, recall that an expected-utility maximizer is risk averse if his Bernoulli index $u$ is concave.

Advance Microeconomics


Reconciling the action of the women in Matt 28:8, John 20:2, and Luke 24:9 with their inaction in Mark 16:8

Question: Matthew, Luke and John say the women left the tomb and shared their news; Mark seems to be saying that they left and told no one because they were afraid. How can these accounts be reconciled?
Answer: Augustine posed almost your identical question in his Harmony of the Gospels:

It may also be asked how it is that Mark says: And they went out
  quickly, and fled from the sepulchre; for they trembled and were
  amazed: neither said they anything to any man; for they were afraid;
  whereas Matthew's statement is in these terms: And they departed
  quickly from the sepulchre with fear and great joy, and did run to
  bring His disciples word.1

He offers two possible explanations:

That Mark is referring specifically to the women speaking  of the angel's words, not of speaking of the fact that the tomb was empty
That Mark is referring to the women not speaking to those men who were there at the tomb:  i.e. the soldiers who were supposed to have been on guard

He explains:

The explanation, however, may be that the women did not venture to
  tell either of the angels themselves,—that is, they had not courage
  enough to say anything in reply to what they had heard from the
  angels. Or, indeed, it may be that they were not bold enough to speak
  to the guards whom they saw lying there; for the joy which Matthew
  mentions is not inconsistent with the fear of which Mark takes
  notice.2

Augustine notes that Matthew records that the women experienced both (initial) fear and (then) great joy, whereas Mark only takes note of their initial fear.
As a further observation, it is perhaps worth noting that the Greek underlying neither said [they any thing] to any [man] (Mark 16:8) has "said" in the aorist aspect (οὐδενὶ οὐδὲν εἶπον), which does not qualify the duration or completion of the action.  We might translate Mark 16:8b as "Neither did they say anything to anyone (at that moment)".

1. Harmony of the Gospels, Book III, Chapter XXIV, No. 64
1. Ibid.
Answer: The reconciliation of the four accounts can be understood by knowing the histories of the New Testament gospels. John Dominic Crossan says in The Birth of Christianity, page 109, the theory that the Gospels of Matthew and Luke were actually based on Mark's Gospel is held today by a fairly massive consensus of contemporary critical scholarship. However, Mark's Gospel originally ended at verse 16:8, with the young man telling the women that Jesus was risen and they fled in terror, telling no one. Mark's Gospel simply left its audience up in the air, wondering what happens next.  In fact, a student of Mark's Gospel may see that the emphasis is not meant to be on the resurrection, but on Jesus' second coming, which will occur within the lifetimes of those to whom Jesus had spoken.
The authors of Matthew and Luke wanted to demonstrate that Jesus really had risen, but had no guidance from Mark (Mark's 'Long Ending' - verses 16:9-20 -  was written long after these gospels were completed). The two evangelists, working independently of each other, therefore wrote what they felt could have happened.

The author of Matthew wrote that an angel came down and told the women that Jesus was risen, and that they were to tell the disciples to go to Galilee, where they would meet Jesus (Matthew 28:2-7). On the way back Jesus met the women and repeated the message. The disciples went to Galilee and met Jesus in a mountain and received the Great Commission to disperse and preach to all nations (Matthew 28:16-20).
The author of Luke wrote that the women found inside the tomb two men who said that Jesus was risen (Luke 24:4-7). When they told the disciples of this, they were not believed, and Peter ran to the sepulchre and looked for himself.
Many scholars believe that John's Gospel was inspired by Luke, but that the author of John made changes for theological reasons. Only Mary Magdalene went to the tomb, but returned to the disciples when she saw the stone had been moved, without seeing anyone or receiving a message for the disciples (John 20:1-2). She told Peter  of her discovery, and Peter and the 'beloved disciple' ran to see what had happened, finding the tomb empty. Mary had come back and when she looked inside, she saw two angels. Turning around, she saw Jesus, whom she thought to be the gardener (John 20:11-16).

Archbishop Peter Carnley, former Anglican primate of Australia writes in The Structure of Resurrection Belief:

The presence of discrepancies might be a sign of historicity if we had four clearly independent but slightly different versions of the story, if only for the reason that four witnesses are better than one.  But, of course, it is now impossible to argue that what we have in the four gospel accounts of the empty tomb are four contemporaneous but independent accounts of the one event.  Modern redactional studies of the traditions account for the discrepancies as literary developments at the hand of later redactors of what was originally one report of the empty tomb...
There is no suggestion that the tomb was discovered by different witnesses on four different occasions, so it is in fact impossible to argue that the discrepancies were introduced by different witnesses of the one event; rather, they can be explained as four different redactions for apologetic and kerygmatic reasons of a single story originating from one source
Comment: This answer appears to be based upon certain assumptions, no evidence is being presented in support of those assumptions.  Crossan's out right denial of the resurrection demands he finds reasons to discredit the resurrection account and therefore casts doubt on the value of his opinion.
Comment: @JonathanChell Regardless of his views on the resurrection, Crossan is correct in asserting that nearly all scholars say that *Mark* was the source used by the writers of the other gospels. This was a statement of fact, not an opinion.  By chance, I could just as easily have cited someone else.
Comment: is he? If that is so you won't have any problem demonstrating it rather then asserting it. The truth is there are 4 main opinions that scholars have discussed, and even if you own the Position of Markian priority is is hard (if not impossible) to argue that the passion accounts are anything other then entirely independent of each other
Comment: In regards to the assertion that Mark's gospel originally ended at 16:8 the reality is that that there are 4 different endings in the ancient textual witnesses. The longer ending was supported by early Christian writers, eg Justin, Irenaeus and Tertullian.
Comment: @JonathanChell I am not sure why you mentioned passion accounts, unless you are confusing the terms passion and resurrection. Although this is not the right forum for a debate, I will make a final comment to end this thread, assuming you actually meant "resurrection accounts": I did indeed say that Matthew and Luke were independent of each other: see  "The two evangelists, working independently of each other..."   Archbishop Carnley takes a more conservative, theological position by saying they are **not** independent but that is not necessarily my position.
Comment: @JonathanChell keep in mind that comments are not meant to debate answers. Voting is the tool for that, and posting alternative answers.
Answer: The answer is straight-forward: Mark is making the point the women did not speak inside the tomb.

And entering the tomb, they saw a young man sitting on the right side, dressed in a white robe, and they were alarmed. And he said to them, "Do not be alarmed. You seek Jesus of Nazareth, who was crucified. He has risen; he is not here. See the place where they laid him. But go, tell his disciples and Peter that he is going before you to Galilee. There you will see him, just as he told you." And they went out and fled from the tomb, for trembling and astonishment had seized them, and they said nothing to anyone... (Mark 16:5-8 ESV)

While it might not be reflected in the translation, Mark's "the women said nothing to anyone" (literally "to none nothing they spoke") uses the singular as to who and what they (did not) say:

καὶ οὐδενὶ οὐδὲν εἶπαν

Luke also describes something which took place inside the tomb:

And as they were frightened and bowed their faces to the ground, the men said to them, "Why do you seek the living among the dead? He is not here, but has risen. Remember how he told you, while he was still in Galilee, that the Son of Man must be delivered into the hands of sinful men and be crucified and on the third day rise." And they remembered his words, and returning from the tomb they told all these things to the eleven and to all the rest. (Luke 24:5-9 ESV)

As in Mark, there is no record of the women speaking inside the tomb and like Mark, Luke states the women were afraid.
The conclusion is that the women did not speak inside the tomb because they were afraid (a natural response to the situation). In addition to Mark, Matthew, Luke, and John agree the women did not speak inside the tomb.
When they leave they told the disciples (and very likely everyone they knew) as Matthew, Luke, and the latter ending of Mark state.


jQuery IE 11 clicks buttons on Enter from keyboard

Question: I have something like an order-page, working with demandware.
I can search for productnames, and I get a list of those.
I click on a product and add it to my cart.
It appears in the cart (on the same page)
There's a jQuery function listening like this:
<code>jQuery("button.removeLineItem").click(function() {
    removeLineItem(getButtonVal(jQuery(this)));
});
</code>
If I press that button, that item is removed from the list again.
My problem is, that this item is being deleted even if I do not actually click the button but click somewhere inside my HTML page and hit ENTER.
Even when the input for the search is focused, it deletes the items.
In Firefox, everything works fine.
I tried to determine keycodes and so on, but without any success.
I tried to use stuff like "blur()" or focus other elements.
I even gave every row an on "onclick()" function but still it's getting executed when I hit enter.
I mean, click() does something like executing everything that is connected to the event.
I also read, that the last element of a form is automatically focused.
But I am not using a form.
ALso, when I deleted all those cart-items by hitting enter; the website tries to execute other buttons.
All problems only in IE 11.
Is there a known bug or anything ?
Anything I could do to prevent this from occuring ?!
Answer: Acutally I just found the solution on stackoverflow:
Button Click event fires when pressing Enter key in different input (no forms)
Just type
type="button" and IE is happy


Brute force without DOS'ing the server

Question: How to conduct brute force tests for directory traversal or other operations that require trial and error without accidentally turning it into DOS attack?
It comes to how much bandwidth a site is capable of (and other things like memory) and it's different as to every site.
How to measure this bandwidth?
How to determine, or calculate and set the right speed of test?
Comment: The bottle neck will probably be the server's max requests/second handling, not the bandwidth as path traversal are simple GET requests with no significant data payload. There are many tools to conduct stress tests which will give you a number. Something like [Siege](https://www.joedog.org/siege-home/) might be useful.
Answer: If you write your own tool, than you can do it with with growing mechanism of requesting.
For example:

Start with 100 threads -> All is ok
Add 50 threads -> 50* errors in 10%
Add 50 threads -> 50* errors in 40%
Remove 70 threads and set 130 for current server. Periodically you can retest this phase.

Manually you can do it with wfuzz, patator or ffuf empirically brute number of threads.
Answer: If you run an enumeration attack and the server is overloaded, then that is a problem the server administrator needs to fix.
What makes a Resource Exhaustion attack work?
Denial-of-Service is a broad term, so let's focus down on resource exhaustion attacks. In most simple terms, resource exhaustion attacks work by you using up most of the available resources, so that the application becomes de facto unusable by normal users.
Generally, a server is expected to serve a lot of people, and even small servers for small companies should have the capabilities to serve a handful of people at the same time.
Most primitively, a resource exhaustion attack is just a measuring contest of who has more resources available. If you have a 10 Gb/s connection and the server has a 100 Gb/s connection, then you won't be able to fully exhaust the server's bandwidth - at least, for primitive attacks.
More advanced would be "amplification attacks", in which you do only very little work, and you get the server to do a lot of work in return. To make an analogy, saying "I want to buy one burger" is about as difficult for you as saying "I want two hundred burgers", but it causes the restaurant a lot more work.
What about brute forcing?
There are many instances in which you may want to run a brute-force attack. Directory enumeration, user enumeration through username oracles, etc...
In general, these attacks do not aim at using up the server's resources, but instead to get a specific answer from the server. Using resources is merely a side effect - one that may be undesirable.
In the best possible case, the server won't limit your requests, and you can just send requests as fast as you can, and get answers as fast as you can. This is usually the case if no server-side rate limiting is implemented and if the server has proper bandwidth compared to you.
However, should you notice that responses are sluggish and delayed, it is time to reduce the load you put on the server. Every brute force tool worth it's salt - no pun intended - will include some kind of delay or rate limiting switch. Start by introducing a small delay, then ever greater delay, until you feel that the packets come in steadily.
Since most tools also run several threads in parallel, it may be worth trying to reduce the amount of parallelism and decrease the delay, or increase the parallelism and increase the delay. It is a trial-and-error process.

Brute force without DOS'ing the server


How to join pieces automatically using interlocking or similar?

Question: I have a piece, which I need to cut into two different pieces, see image 1.
Image 1

Then I need to make interlocking joints or similar, see image 2.
Image 2

How can I do that automatically, using Solidworks or another program?
It's an <code>*.STL</code> file so I can easily manipulate all parts without any errors.
Answer: I'm not qualified to advise regarding Solidworks, but can suggest a process and concept from which you may be able to adapt to your software.
As you have the two pieces currently in STL form, it makes things only slightly more difficult. Consider to align them parametrically so the faces contact and the edges are coincidental. The block STL will appear as a single cube, in the example you've provided.
Create and place a mating cylinder piece in the desired position as you've shown in the second image. It is a common feature of many 3D modeling programs to be able to perform a subtraction of one part from another. It is equally common to be able to merge two parts into a single manifold part.
Save the file containing the three parts.
Select either block and the cylinder. You can delete or otherwise hide or deselect the unused block. Perform a subtraction on the remaining pair. Save this file under a different name.
Reload the three parts file.
Select the other block and cylinder, perform a union of the pair. Save this file under a different name.
Rather than saving the three parts in a file, one can frequently save the joined or subtracted part and perform an undo until the three parts return. This is a faster more convenient method.
I have performed the above steps in Meshmixer and know that it can be done in Blender, if one is skilled in these programs.
I've performed an internet search for "perform boolean subtraction solidworks" and found multiple results for this process. One link references the "cavity" feature for subtraction. I did not search for boolean union and leave this as an exercise for the reader.
Consider also to plan for this activity in the future by leaving the block intact, unsliced, place the cylinder, perform the boolean action, then slice it as desired. The sequence of saves and/or undo actions will be different from above, but may be easier than re-aligning a previously sliced "block" or item.


Hibernate: loading a class by its field without a table

Question: I have an Ink class with a fixed set of constants. They never change and I don't want to store this class as a table.
public final class Ink {
    public static final Ink Y = new Ink(91001, 'y', 90.70,  -5.23,  94.37), "Yellow");
    public static final Ink M = new Ink(92001, 'm', 48.19,  72.01,  -1.78), "Magenta");
    public static final Ink C = new Ink(93001, 'c', 56.46, -41.00, -43.50), "Cyan");
    public static final Ink K = new Ink(94001, 'k', 18.64,   1.80,   5.21), "Black");

    public int code;

    public static Ink forCode(int code) {
        //...
    }

    //...
}

Other classes can have Ink ink or Collection<Ink> inks fields, but every ink instance must be mapped as a simple integer column with its code value only. Code is not a foreign key or something – it is a simple integer value from which I can always obtain Ink instance.
@Entity
public class Order {
     //...
     @OneToMany
     public Set<Ink> inks;
     //...
}

I can use converter to restore Ink class by its code and back
@Converter(autoApply = true)
public class InkConverter implements AttributeConverter<Ink, Integer> {

     @Overrcodee
     public Integer convertToDatabaseColumn(Ink ink) {
         return ink.code;
     }

     @Overrcodee
     public Ink convertToEntityAttribute(Integer code) {
         return Ink.forCode(code);
     }
}

but the question is:
how to prevent Hibernate from mapping the class as a table and still have a class field loaded from its code column?
Comment: Why would Hibernate map __Ink__ as a table when it doesn't have an @Entity annotation? No compliant JPA implementation would do that.
Answer: As you store the ink in your Java code. So you should implement the load action all by your self. First, you can prevent Hibernate from mapping the class as a table by annotation @Transient. And then you can handle the load action after order loaded:
public interface Inked {
    getCode();
    setInk(Ink ink);
}

public abstract class AbstractEntity {

    @PostLoad
    public void loadInk() {
        if(this instanceof Inked){
            Inked inked = (Inked) this;
            inked.setInk(Ink.forCode(getCode()));
        }
    }
}

@Entity
public class Order extends AbstractEntity implement Inked {
    //...
    public Integer code;

    @Transient
    public Ink ink;
    //...

}

Comment: Good, but in this case I need to attach`loadInk()` and `code` to every entity with `Ink` field.
Comment: If you have many entity to have the ink. May be you do it use the interface. Code updated.
Answer: Firstly, you can create an Enum to represent Ink instances. If you can change the column to store a char reference (Y,M,C,K) rather than code this would the easiest solution. If not then you can use a converter as you have suggested to convert from the code to the Enum instance.
public Enum Ink {
    Y = new Ink(91001, 'y', 90.70,  -5.23,  94.37), "Yellow");
    M = new Ink(92001, 'm', 48.19,  72.01,  -1.78), "Magenta");
    C = new Ink(93001, 'c', 56.46, -41.00, -43.50), "Cyan");
    K = new Ink(94001, 'k', 18.64,   1.80,   5.21), "Black");

    .....

    private static Ink (...) {
        ...
    }
}

Mappings would be like the below if you save Y,M,C,K. If you must save the code then add the necessary converters (http://www.nurkiewicz.com/2013/06/mapping-enums-done-right-with-convert.html)
@Entity
public class Order {

     @ElementCollection
     @CollectionTable(...)
     @Enumerated(EnumType.STRING)
     public Set<Ink> inks;

     @Enumerated(EnumType.STRING)
     private Ink ink;
}


If sigmoid activation function is prone to vanishing and exploding gradients can we not use it in final layer of binary classfication?

Question: Many paper and books say that sigmoid activation function with random intialization is prone to vanishing/exploding gradients therefore it is better to use LeakyRelu, Elu, or Relu. Does this mean that we should use them in final layer of binary classificiation as well?
Answer: Vanishing & Exploding Gradient problem happens in case of deep neural network. In NN when we have to update weights & biases for each layer we calculate the partial derivate with respect to y_hat at each layer (Back Propogation Algorithm). Because in this case weights are multiplied in chain with each other.
As Sigmoid is used in last layer it will only be just gradient and does not have impact of other layer while initial layer will be multiplies by weights of earlier layer leading to Vanishing Gradient problem.
So Sigmoid in last layer does not lead to Vanishing Gradient problem and you can use it safely.
Answer: There's no problem using the sigmoid function in the final layer. Vanishing/exploding gradients only become a issue when the sigmoid function is used across multiple layers.
Sigmoid is used "behind the scenes" when you use the softmax function for multi-class classification. A sigmoid function is used for each class label, these are then normalised so the class probabilities across all labels sum to 1.


How to control a System that tends to Zero

Question: For a design project in a Control course, my classmates and I must create a Controller that steers an unknown system to a given trajectory within certain constraints. The system is given to us in Matlab, and we use Simulink to observe the output of the system when given an input of our choice. As we can only observe the input-output behaviour of our nonlinear, time-variant system, we have come up with a Transfer Function that heuristically models our system behaviour (by creating a Bode plot). A snapshot of our Simulink model can be seen here.
Currently, we are investigating a closed-loop feedback approach, and we have found that our system is tending towards zero whenever given a constant input. The function we wish to mirror is a simple step function, with a step size of 1. However, we find that our system error always tends toward one instead of zero, and it does not follow the input trajectory at all.
We have considered pole-cancelling and PID controllers, and have been unsuccessful so far. Does anyone have an idea of an approach to use that would stop our system from tending towards zero?
Answer: With this controller
$$ C=\frac{0.001(s+100)}{s(s+1)(s+0.001)} $$
you get very close to the bandwidth limit imposed by the right-hand-planes zeros of your plant.


User created chat rooms in Tigase

Question: In Tigase, how a connected user can "creates chat rooms" which are visible to all the contacts in roster so that any of them can "join" the room (with creator's permission)
Thanks!
Answer: As far as I know there is no such thing in the XMPP protocol specification, hence it is not available in the Tigase server. The simplest way to achieve something like this would be to create a chat room and put a link to the room in the presence status message. This message would be automatically visible to all contacts in the roster.
They could click on the link and join the room.
However, the main issue is whether the XMPP client you use understands XMPP links and can join room after the link is clicked.

User created chat rooms in Tigase


Error code P1061 on a Dodge Dart?

Question: I have an error code P1061 in a 2015 Dodge Dart, 2.4L engine. How do I resolve this? Thanks!
Answer: P1061 is a "Cylinder 1 oil supply solenoid valve stuck shut" code.

If you've recently had your oil changed check to see that the correct weight oil was used and check to see if a OEM oil filter was used (the oil filter may not be as big an issue as having the correct weight oil, certain Jeep engines, the 3.7? need a filter with some valve or something inside of them for correct oil pressure.)
Check your engine oil level.

The MultiAir block known as the Variable Valve Actuator Assembly currently isn't serviceable and needs to be replaced as a whole unit. If the car has no obvious performance issues you may want to document the code and clear it. If it comes back there's an obvious issue and should be taken back to the dealer for warranty work.
Answer: This fault indicates a low-voltage on the fuel rail pressure sensor. Check your fuel hoses at the fuel rail for leaks and disconnects.
If everything is on tight with no leaks, measure your fuel pressure with the engine on, make sure you actually have fuel pressure for the sensor to read.
If you have fuel pressure, do an electrical test on the pressure sensor. This involves a multi-meter and reading the voltages output by the sensor. You should get 5V from the power pin with the engine on. Then check the data pin with the engine on and off: you should get 0V with the engine off (no fuel pressure) and something closer to 5V with the engine on (normal fuel pressure). The 2nd link I gave you has a generic chart for voltages and fuel pressures, matchup your voltage and your pressure. If they don't match, your sensor is reading incorrectly and needs to be replaced.
Comment: This may be incorrect, I believe the code is for the MultiAir system found on newer Chrysler and Fiat cars.
Comment: Verified through service information that the newer 2.4 engine doesn't use a fuel rail pressure sensor.
Comment: Yeah, the P1xxx codes are manufacturer specific. The website I looked up only says that way down at the bottom and doesn't even say which manufacturer this fuel rail pressure code is for.

Error code P1061 on a Dodge Dart?


Linux. Technologies that allow to work with scanner from WEB page?

Question: I have to deal with scanner from WEB-page. I can use Active-X (TWAIN / WIA) and Silverlight (WIA) on Windows (may be Flash also?). What technologies may I use on Linux to access scanner from web-page?
Thank you in advance!
Answer: You can also develop NPAPI plugin that interact with scanner (TWAIN/WIA). That also support scripting and you can access to JavaScript methods, objects and DOM model in scope of your HTML page. For IE you can develop IE plugin like toolbar.
For example, there's an open source project called FireBreath which allows you to write a plugin for IE (ActiveX) and NPAPI (Firefox, Opera, Chrome etc.) from a single codebase.
Answer: You can use Java Applet. Have you seen JTwain: http://asprise.com/product/jtwain/faq.php. It's a commercial tool but might be of help to point you in the right direction
Answer: you can try SANE for scanning in Linux. It's open source: http://www.sane-project.org/ .


Orientation of points in cell complexes

Question: On page 268 - 269, Hatcher defines the notion of an orientation of a cell in his book on algebraic topology. He writes that for a cell complex $X$ with skeleton filtration $\varnothing =: X^{-1} \subseteq X^0 \subseteq X^1 \subseteq \dots \subseteq X$, we have that $$H_n(X^n,X^{n - 1})$$ is free abelian with basis in 1:1 correspondence with the $n$-cells of $X$. But there is a sign ambiguity for the cells, i.e. we could choose $e^n$ or $-e^n$ since both are generators for the $\mathbb{Z}$-summand. What I do not understand is, he moreover writes, that for $n = 0$, this choice is canonical. I mean, we have that $$H_0(X^0,X^{-1}) = H_0(X^0) \cong \bigoplus_{0 \text{ cells } e^0} \mathbb{Z}e^0$$ and by the dimension axiom we moreover know that $0$-cells $e^0$ are generators of the $\mathbb{Z}$-summands. But why should this choice be canonical? I mean, I could simply choose $-e^0$. Is this due to the fact that $e^0$ are points, i.e. $e^0 = x \in X$, and $-x$ does not make "sense" in the topological space (but in homology of course)?
Comment: I would write $-(x)$ rather than $x$...just to make the point one is dealing with a $0$-chain. You could of course choose some or all  of  the $-(x)$ rather than the $(x)$ to form a basis of the $0$-chain group, but why on earth would you bother?
Comment: @LordSharktheUnknown Because Hatcher writes this choice is canonical. I would rather say it is a convention, not a canonical choice.
Answer: You could choose $-e_0$, but the canonical choice is $e_0$. It's like choosing an orientation for $\mathbb{R}$, sure, you can choose -1, but the canonical choice is 1.
The thing is that for a vertex, you only have one way of mapping a singleton to your space with value your vertex. But for example, for an edge, you have two ways of mapping an interval to your space with value your edge: in one direction or the other. And if I just give you the space, you have no way of knowing which one I chose when I built the space if I don't tell you. The cell decomposition for the 0-skeleton is unique, but not for the higher skeletons.
Comment: Exactly what I thought...but then it is more of a convention rather than a canonical choice, isn't it? Or do you have some insights, why it is actually canonical?
Comment: I expanded my answer a bit.
Comment: Very nice! Thank you.

Orientation of points in cell complexes


DeepLearning4J - ParagraphVectors: Why is similarity negative?

Question: I'm using the ParagraphVector tool in DeepLearning4j framework. What I'm doing is training a model on a set of text documents and then calculating the similarity between those documents.
Now, as the reference page (http://deeplearning4j.org/word2vec) says, the metric used by the tool to calculate similarity is cosine similarity, which should be included between 0 and 1. However, for some pair of documents, I get negative scores.
Can anybody tell why is that?
Thank you in advance.
Answer: By definition cosine similarity can be within [-1, 1]. https://en.wikipedia.org/wiki/Cosine_similarity
So technically it's still possible to get negative values for w2v/d2v.
However, usually you won't see -1 or even something close to that.


How did Schrödinger do quantum mechanics with wave functions?

Question: On my way to learn about the very beginning of quantum mechanics and its different formulations, starting with Heisenberg infinite matrices and Schrödinger's wave functions, I can really not find till now a single reference in which it is explained how Heisenberg and Schrödinger were doing quantum mechanics i.e. determining probabilities about measurements for positions and general observables within their own formulation framework of, respectively, infinite matrices and wave functions (i.e. without talking about Heisenberg and Schrödinger's pictures inside a Hilbert space 2(ℝ) for example). I mean for example for Schrödinger, given a wave function () of a fixed system, say an electron, what was exactly his interpretation of ()? (Before Born's interpretation came I mean) and how he did to do computations with it in order to predict the probabilities for the position, the momentum the energy and so on?
Comment: Others will surely provide several references to look at, but I thought I'd mention a book I've had for a long time (since 1977 I think) and keep wishing I'd take the time to go through it -- [**The Quantum Physicists and an Introduction to Their Physics**](https://www.amazon.com/dp/0195008618) by William H. Cropper (1970). Every time I look over this book I'm amazed at how well it appears to cover the type of concerns you bring up. Moreover, at least to me, the book seems **(continued)**
Comment: pitched at that rare level between a gobbledygook profusion of technical words without really conveying any understanding beyond how the words are used by physicists (what I find a lot of popularizations of physics do, especially recent decades stuff involving Hawking, Penrose, Witten, etc.) and highly technical math jargon that to me can often appear designed to conceal whether an argument is mathematically rigorous or only mathematically suggestive. *(moments later)* See also [A technical and historical introduction to quantum mechanics](https://hsm.stackexchange.com/q/13094/264).
Comment: Thank you so much for the reference @Dave L Renfro
Answer: I don't think Heisenberg and Schrödinger calculated probabilities at the beginning, as the role of probabilities in quantum mechanics was not known then. Schrödinger initially interpreted the squared magnitude of the wave function as the charge density.


How can I farm credits quickly?

Question: With the new Rising Tide update, I need 6 million credits to build my own railjack. What are the easiest/quickest ways to farm credits quickly?
Answer: Generally speaking, if you want to farm credits quickly, you will want to have a credit booster, but it is not required. You can get a credit booster from the market, Baro Ki'teer, Rare/Reinforced storage containers, or Daily Tributes.
Sell Duplicates
The first thing to do when looking for credits is to check how many duplicate blueprints and mods you have, as they can be sold for credits. There are a number of blueprints, such as Oberon parts, that drop very frequently, and each one can be sold for 3,500 credits, so sell your extras that you don't need. You can also sell mods for credits if you have extra duplicates and don't need endo.
Dark Sectors
The least difficult way to farm credits is to do Dark Sector missions, as they reward 10,000-20,000 credits per completion which is doubled with a booster. You will only face infested enemies ranging in levels 6-40 based on the planet, making it relatively easy to solo. Popular nodes for this are Akkad/Eris, and Seimeni/Ceres where you can get 18,000 and 20,000 credits for completing 5 waves. This bonus will be doubled if you have a Daily First Win Bonus and combined with a credit booster, it is quadrupled.
Sortie
Another method of farming credits is to do the daily sortie. You will receive 20,000 for the first mission, 30,000 for the second mission and 50,000 for the third. However, this can only be done once a day, and you will have to face enemies level 60-100 so it is not necessarily easy for newer players.
Neptune Disruption
You can also farm credits doing Laomedeia, Neptune, a Disruption mission which rewards 20,000, 30,000, and 50,000 credits for Rotation A, B, and C respectively, and enemies start at levels 25-30
Index
The most popular method of farming credits quickly is the Index. If you have a properly equipped team, you can farm credits very quickly, however the enemies are fairly high level, and have a lot of armor/shields depending on the difficulty you select. There are 3 difficulty levels for the Index

Low: Investment- 30,000 Return- 105,000 Required Points- 50
Medium: Investment- 40,000 Return- 175,000 Required Points- 75
High: Investment- 50,000 Return- 250,000 Required Points- 100

Where enemy starting level increases with difficulty and scales with rounds.
To do the Index effectively, you will want to have the following team composition. (While not required, it speeds the process up and lowers chance of failing and losing credits. Highly recommended for high risk Index.)

Goalie (Need at least 1): Limbo, Gara, Khora, Frost

Limbo is generally regarded as the best as he can be immune to damage in his void while having everything frozen that walks into his cataclysm. Also, offers a safe place for the DPS to hide.

DPS (Recommended at least 1): Mesa, Banshee (Sonar), Nova (100-130% power strength), Excalibur Umbra
Point Carrier (Need at least 1): Rhino, Revenant

Need to be tanky in ways other than Health/Shields as financial stress from picking up the points lowers your max health/shields and depletes your energy. Iron Skin and Mesmer Skin are the best ways to deal with this.

Support (Recommended 1): Trinity (EV)

Picking up points depletes your energy, so having an EV Trinity to refill energy makes life easier for everyone. Also, EV Trinity has good single target damage.

Best weapons for the index are usually high damage status shoguns, such as Kohm, Tigris Prime, Hek. High damage crit based pistols are also useful, such as Pyrana (Prime), or various kitguns. Any high damage melee can also work.
To find a group for Index runs (most Pick up squads are chaotic), look in recruiting chat for people who are hosting Index runs, or host one your self. If you are posting a message in chat to try to find a group, use something like the following format.

LF High Index. Can play Rhino/Limbo
  H High Index. 2/4 Need Point carrier and dps
Comment: Trinity isn't the only viable support. Wisp is surprisingly effective at countering Financial Stress as long as she places her Reservoirs in good positions. I find it helps to have only the Vitality and Haste reservoirs up so you can set up 3 sets instead of 2.
Comment: Profit taker is good too
Answer: General Tips

In general, you'll want a credit booster active while farming to maximize your credit gains. This won't apply to sold items, and only apply to mission rewards and credits dropped off of enemies. You can gain boosters without using platinum by:

Waiting for Baro Ki'Teer to offer a 3-day Credit Booster in his stock
Get lucky on a Daily Login Reward and receive a timed Credit Booster
Wait for a DE hosted 2x credit weekend for even more gains, as DE triggered events also stack with normal credit boosters.

Use Warframes that can boost your credit gains. Every single bonus credit you get adds up, and these applies to Warframes and gear items that can boost your gains without too much investment. Things like:

Nekros / Nekros Prime's Desecrate
Chroma / Chroma Prime's Effigy
Secura Lecta's 2x credits on kill modifier
Smeeta Kavat's Charm bonus can yield double credits for a set amount of time

The Index
Spamming low-risk investments is your best bet here. Avoid medium and high risk investments, as the seemingly high profit amounts are a trap -- the time spent to reach those levels is far longer than running the low risk investments over and over.  Advisable frame setups are a pure HP focused Inaros, Iron Skin focused Rhino, and weapons that have high one-shot kill capabilities and scale well up into high levels (ie Tigris/Prime, Catchmoon, etc).
There are a few more benefits to running low-risk investments over and over. In addition to having the highest credit to time ratios, due to the nature of enemy level scaling, you are also afflicted with no default financial stress modifier, and thus can survive longer without the need for hyper-specialized builds.
Arbitrations
Arbitrations always give Credits 50,000 per completion. If you complete an Arbitration mission after you first login per day, this will be doubled to Credits 100,000.
Because the Sortie timer and the daily login timer are independent of each other (about 7 hours apart), you can exploit this to complete the first two Sortie missions, then complete the third Sortie after the daily login timer resets for an easy doubled first win bonus reward of Credits 100,000.
Orb Vallis (Open World Venus)
Defeating the Profit-Taker Orb gives a base amount of Credits 125,000, but this may be less desirable for newcomers due to the requirements as well as difficulty of the fight to begin with.
Dark Sectors
Hieracon on Pluto is one of the fastest ways to farm credits. Since it's an excavation mission, extracting after the first excavator has finished will yield Credits 20,000 in under 5 minutes. However, bear in mind that defending the extractor and keeping the power up may be hard for a lone player, so it's advised to bring someone along.
Sechura on Pluto, and Seimeni and Gabii on Ceres will give Credits 20,000 after the first 5 minutes/waves, extracting in the 5th minute/wave under few runs (3 or 4) will give high amounts of credits, Bear in mind the more people you have in your squad, the more credits you get (increasing by approximately Credits 1,000 per additional player).
Source
Comment: Inaros isnt that great due to the max health reduction from financial stress
Comment: @Dragonrage If you are spamming low risk investments, which reward the most amount of credits earned per time ratio, then you will have a lot less Financial Stress at max points banked, compared to Medium and High risk investments
Comment: Given that it isnt efficient to only do 1 round of index, and 15 points held is the most efficient to turn in with, you will eventually have to deal with higher level enemies, and the financial stress debuff is still relevant
Comment: @Dragonrage Not sure what you're talking about. 3 turn ins at 15 yields 45, and at that point you only need 5 more kills to finish.Low Risk Index is far more efficient than Medium and high Risk, not only are you hitting a wall with level 100+ enemies as you attempt to finish up your points from 50-100, enemies are tougher and soak up more shots.
Comment: Just so we're clear, you do know that the profit from one round of Low Risk is 75,000 and the profit from one round of High Risk is 200,000?
Comment: @Powerlord Yes, and the time it takes to run Low Risk is signficantly lower than the time to run High Risk.   It has been debunked on Reddit countless times, it is far more efficient to run low index than to run High index.

How can I farm credits quickly?