Links for August-September 2017

On nuclear decommissioning:

For nuclear power plants governed by the United States Nuclear Regulatory Commission, SAFSTOR (SAFe STORage) is one of the options for nuclear decommissioning of a shut down plant. During SAFSTOR the de-fuelled plant is monitored for up to sixty years before complete decontamination and dismantling of the site, to a condition where nuclear licensing is no longer required. During the storage interval, some of the radioactive contaminants of the reactor and power plant will decay, which will reduce the quantity of radioactive material to be removed during the final decontamination phase.

The other options set by the NRC are nuclear decommissioning which is immediate dismantling of the plant and remediation of the site, and nuclear entombment which is the enclosure of contaminated parts of the plant in a permanent layer of concrete.Mixtures of options may be used, for example, immediate removal of steam turbine components and condensors, and SAFSTOR for the more heavily radioactive containment vessel. Since NRC requires decommissioning to be completed within 60 years, ENTOMB is not usually chosen since not all activity will have decayed to an unregulated background level in that time.

Researchers think that this ‘turbulence cascade’ explains how even fluids with low viscosity — such as gases in the atmosphere, where there is little resistance between moving layers — still quickly convert their kinetic energy into heat and slow down when turbulence kicks in. Turbulence spreads energy into increasingly tiny eddies, which, at their smaller scale, increase local viscosity. Like friction between solid objects, this viscosity acts to increase resistance to movement between layers of fluid, and thereby dissipates kinetic energy as heat.

Mathematicians are pushing exploration of low-viscosity fluids to their ultimate limit. The physicist, chemist and mathematician Lars Onsager suggested in 1949 that, in theory, a fluid could still dissipate energy even if its viscosity were to become vanishingly small, or zero (a situation that is never seen in the real world). In this hypothetical scenario, the fluid’s motion will just keep dispersing into infinitesimally small eddies, where it still will die out eventually. “That was kind of a shocking idea,” says Philip Isett, a mathematician at the University of Texas at Austin.

My purpose is to explain the ‘essential content’ of ‘the’ Threshold Theorem. By ‘essential content’, I mean those aspects of the theorem which justify a belief that quantum computing is indeed possible in practice. I divide this essential content into two categories: promises about the noise affecting a device and the guarantee that a given quantum circuit can be altered so as to be robust against the promised noise model.

In new research they plan to present at the USENIX Security conference on Thursday, a group of researchers from the University of Washington has shown for the first time that it’s possible to encode malicious software into physical strands of DNA, so that when a gene sequencer analyzes it the resulting data becomes a program that corrupts gene-sequencing software and takes control of the underlying computer….

the natural stability of DNA depends on a regular proportion of A-T and G-C pairs. And while a buffer overflow often involves using the same strings of data repeatedly, doing so in this case caused the DNA strand to fold in on itself.

The oldest carbon-14-dated seed that has grown into a viable plant was Silene stenophylla (narrow-leafed campion), an Arctic flower native to Siberia. Radiocarbon dating has confirmed an age of 31,800 ±300 years for the seeds…Scientists extracted the embryos and successfully germinated plants in vitro which grew, flowered and created viable seeds of their own.

Here are more bets that Peter Woit listed three years ago.

…is a phenomenon observed in some tree species, in which the crowns of fully stocked trees do not touch each other, forming a canopy with channel-like gaps….There exist many hypotheses as to why crown shyness is an adaptive behavior, though research suggest that it might inhibit spread of leaf-eating insect larvae.

The N1…was a super heavy-lift launch vehicle intended to deliver payloads beyond low Earth orbit…. Its first stage is the most powerful rocket stage ever built.

The N1-L3 version was developed to compete with the United States Apollo-Saturn V to land a man on the Moon, using the same lunar orbit rendezvous method.

N1-L3 was underfunded and rushed, starting development in October 1965, almost four years after the Saturn V. The project was badly derailed by the death of its chief designer Sergei Korolev in 1966. Each of the four attempts to launch an N1 failed; during the second launch attempt the N1 rocket crashed back onto its launch pad shortly after liftoff and exploded, resulting in one of the largest artificial non-nuclear explosions in human history. The N1 program was suspended in 1974, and in 1976 was officially canceled. Along with the rest of the Soviet manned lunar programs, the N1 was kept secret almost until the collapse of the Soviet Union in December 1991; information about the N1 was first published in 1989.

As to cost [this] suggests it’s 10-25% cheaper to operate, but when you factor in capital costs, it’s 40-90% more expensive, if I’m reading the abstract correctly.

Rubi dramatically out-performs Maple and Mathematica (the two major commercial computer algebra systems) on a grueling integration test suite. Consisting of over 55 thousand integrands and optimal antiderivatives, the entire test suite is also available for downloading.

The Rubi integration package for Mathematica has a verbose setting that lets you view the steps it took to perform integration.

The Grand Canal (also known as the Beijing-Hangzhou Grand Canal), a UNESCO World Heritage Site, is the longest canal or artificial river in the world and a famous tourist destination.[1] Starting at Beijing, it passes through Tianjin and the provinces of Hebei, Shandong, Jiangsu and Zhejiang to the city of Hangzhou, linking the Yellow River and Yangtze River. The oldest parts of the canal date back to the 5th century BC, but the various sections were first connected during the Sui dynasty (581–618 AD). The Yuan and Ming dynasties significantly rebuilt the canal and altered its route to supply their capital Beijing…

The total length of the Grand Canal is 1,776 km (1,104 mi)…

The southern portion remains in heavy use to the present day.

(H/t Tyler Cowen.)

Of the 12 [journal] titles on Suber’s list that left to start up new titles, 10 have comparable impact factors between the old journal and the new journal….six have an impact factor [IF] greater than that of the title from which the editors split at the time of the split. Four of the new titles have impact factors that are less than the boycotted title’s IF at the time of the split. Compared to the current IFs of boycotted titles, the IFs look a bit better for the new journals; seven of the new titles were better rated than the title that was subject of the revolt. The average impact factor of the new title is more than 50% greater than the boycotted title, with one outlier that is more than five times better off than the boycotted title.

I’d be very interested in interviewing people who continued to submit to the old journal. Would they be more likely to endorse “I didn’t realized the editorial board changed” or “I think the publisher is more important to making a good journal than the editors” or “I think everyone else will continue to think this is the top tier journal” (a la a Keynesian beauty contest).

Other termination shocks can be seen in terrestrial systems; perhaps the easiest may be seen by simply running a water tap into a sink creating a hydraulic jump. Upon hitting the floor of the sink, the flowing water spreads out at a speed that is higher than the local wave speed, forming a disk of shallow, rapidly diverging flow (analogous to the tenuous, supersonic solar wind). Around the periphery of the disk, a shock front or wall of water forms; outside the shock front, the water moves slower than the local wave speed (analogous to the subsonic interstellar medium).

Female users can also opt for a chaperoning feature whereby all of their in-app chats are emailed to a wali/guardian, should they wish to observe this type of Islamic etiquette.

And:

They tell a funny story about how they were emailed by a man from Uganda thanking them for helping him meet his wife via the app — and when they went to check exactly how many users they had in Uganda it was, well, just those two. “When it’s meant to be, it is meant to be!” says Younas.

The fact that they claim it should be near the most distant part of its hypothetical orbit makes me a bit suspicious. This sounds like the natural astronomical way to square a misunderstood signal in the data (the orbits of the visible planets) with the apparent invisibility for Planet Nine (put it far away).

More caveats to Planet Nine’s theorized existence come from the Cassini probe, which has orbited Saturn since 2004. From minute changes in the spacecraft’s speed and other telemetry, the Cassini team calculates the distance from Earth to Saturn to within 3 meters. Those range measurements could reveal even small deviations in Saturn’s orbit due to the pull from Planet Nine, but only if it is close or large enough. William Folkner, a principal engineer at JPL, says he and coworkers examined the data and saw no perceptible distortion of Saturn’s orbit. So, if Planet Nine exists and is 10 times Earth’s mass, it must be within 25 degrees of the farthest point in its hypothetical orbit, he says.

Still, the apparent axial alignment of the orbits of 12 trans-Neptunian objects is striking.

Interestingly, when discussing the symplectic integration numerical technique, the article links to a paper by Jack Wisdom, whose textbook I’ve praised before.

Sperm counts in men from America, Europe, Australia and New Zealand have dropped by more than 50 percent in less than 40 years, researchers said on Tuesday.

They also said the rate of decline is not slowing…

Levine screened and brought together the findings of 185 sperm count studies from 1973 to 2011 and then conducted a so-called meta-regression analysis.

The results, published in the journal Human Reproduction Update, showed a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm count among North American, European, Australian and New Zealand men…

In contrast, no significant decline was seen in South America, Asia and Africa. The researches noted, however, that far fewer studies have been conducted in these regions.

Experts asked to comment on the work said it was a comprehensive and well-conducted analysis and did a good job of adjusting for confounders that could have skewed its findings.

Incidentally, there’s now a PsyArXiv which looks reasonably reputable, currently hosting more than 600 papers, including this one (H/t Carl Shulman) advocating for a more stringent cut-off before something is declared “statistically significant”. I’ll link again to this very good post by Holden Karnofsky arguing that, because of various real-world inefficiencies, we should fund a smaller number of high-quality studies, for fixed resources, insofar as we actually want those studies to be useful to outsiders.

There’s a theory [0] [1] that it’s mostly down to aesthetics. It looks visually more pleasing that way when split into three groups of four numbers:
I, II, III, IIII (consisting of I only)
V, VI, VII, VIII (consisting of I and V)
IX, X, XI, XII (consisting of I and X)

Here we report a reconstructed ancient genome of Yersinia pestis at 30-fold average coverage from Black Death victims securely dated to episodes of pestilence-associated mortality in London, England, 1348–1350. Genetic architecture and phylogenetic analysis indicate that the ancient organism is ancestral to most extant strains and sits very close to the ancestral node of all Y. pestis commonly associated with human infection….Comparisons against modern genomes reveal no unique derived positions in the medieval organism, indicating that the perceived increased virulence of the disease during the Black Death may not have been due to bacterial phenotype. These findings support the notion that factors other than microbial genetics, such as environment, vector dynamics and host susceptibility, should be at the forefront of epidemiological discussions regarding emerging Y. pestisinfections.