They don't mention Researcher Allegiance Effect. Therefore I suspect they did nothing about it. Given the nature of the study, I feel comfortable ignoring the results on that alone, without bothering to find specific methodological flaws.
Rename doesn't always do what we want. The one serious investigation I've seen [1] unhelpfully states that "[W]hen a file is appended, and then renamed ... many file systems recognize it and allocate blocks immediately." Suggesting that some file systems don't, but failing to name them. In general, appends followed by directory operations are not order-preserved.
(Strictly speaking there is a problem in the rename because we can't be sure "tmpfile" still refers to the same inode. It would be nice to have a way to link fds, but I'm not aware of any).
According to the paper, existing file systems recognize the (open,) write, rename pattern and don't reorder write and rename. That would break too much existing code. But these are filesystem-specific design decisions.
Btw. it's just the same with CPUs writing to memory. Generally writes can be reordered if the behaviour is not visible to the executing thread. However if there are multiple threads you might need to insert (CPU-specific) memory barriers to prevent reorderings that are visible to other threads. x86 is like those file systems here in that most incorrect code still works, because x86 makes some ordering guarantees.
1934: This is predicted
1997: This is done http://www.nytimes.com/1997/09/16/science/scientists-use-light-to-create-particles.html
2014: We will "demonstrate the feat within the next 12 months"
2015: Didn't bother
"Photon–photon scattering and other effects of nonlinear optics in vacuum is an active area of experimental research, with current or planned technology beginning to approach the Schwinger limit.[5] It has already been observed through inelastic channels in SLAC Experiment 144.[6][7] However, the direct effects in elastic scattering have not been observed. As of 2012, the best constraint on the elastic photon–photon scattering cross section belongs to PVLAS, which reports an upper limit far above the level predicted by the Standard Model.[8] Proposals have been made to measure elastic light-by-light scattering using the strong electromagnetic fields of the hadrons collided at the LHC.[9] Observation of a cross section larger than that predicted by the Standard Model could signify new physics such as axions, the search of which is the primary goal of PVLAS and several similar experiments. Even the planned, funded ELI–Ultra High Field Facility, which will study light at the intensity frontier, is likely to remain well below the Schwinger limit[10] although it may still be possible to observe some nonlinear optical effects.[11] Such an experiment, in which ultra-intense light causes pair production, has been described in the popular media as creating a "hernia" in spacetime.[12]"
The usual pattern is that only one X chromosome gets transcribed in any given cell.[1] This keeps the dosage of all those proteins correct. Otherwise there would need to be a separate set of dosage controls for XX and XY people.
The inactivation occurs pretty early in life, and when cells replicate they keep the inactivation. This results in macroscopic regions of the body with consistent inactivation. Usually this isn't noticeable, but in cats coat pigment is on the X chromosome, and heterozygous cats often show "tortoiseshell" or "calico" coloring. The patches of contiguous color there are larger than a retina.
So it seems entirely likely that all the cells in a human woman's retina would use the same X chromosome.
On the other hand, that predicts half of het women would be colorblind, which isn't observed. So maybe not so simple...
I have a second thought about downstream neural hookups and the mechanisms for those, but it'll have to wait for later.
The article explains X-inactivation, and it doesn't play the role you think here: both copies are broadly equally expressed among retinal cells. Also even if all cells in a retina used the same X-chromosome copy it doesn't predict color-blindness, since we would still have a trichromatic system.
The answer to the question posed by the title is simply that all mutant fourth cone types are not created equal. Most have a spectral response curve similar enough to an existing type not to make a real difference; a few have peak responses more squarely in-between those of the usual trichromat photopigments, allowing more finely graded color perception. (The article takes its time getting round to explaining this, but it's all there.)
When those senior doctors are out of town, are risky-but-necessary procedures performed by less senior doctors or delayed until the senior ones return?
Actual descriptions of medical tests routinely give both rates. They often call them "sensitivity" and "specificity". Good luck remembering which is which.
But if only one rate is given, that indicates they're equal. If they're not, then it's reasonable to describe the documentation as incorrect.
If you get the password to one of my unimportant accounts, you get the password to most of them. They're unimportant, but still...