Friday, January 11, 2019

Strained quantum dots have 'blink-free' light emission

Novel colloidal quantum dots (top) are formed of an emitting cadmium/selenium core, LANL graphic

Quantum-dot researchers at Los Alamos National Laboratory have found that intentionally squashing colloidal quantum dots (in other words, creating asymmetrical strain) during chemical synthesis creates dots capable of stable, blink-free light emission that is fully comparable with the light produced by dots made with more complex processes. The squashed quantum dots emit spectrally narrow light with a highly stable intensity and a nonfluctuating emission energy.

The strained colloidal quantum dots represent a viable alternative to presently employed nanoscale light sources, and deserve exploration as single-particle nanoscale light sources for optical quantum circuits, ultrasensitive sensors, and medical diagnostics. (Full Story)

Now we know how fast a black hole spins when it shreds a star

Artist's conception of a tidal disruption event, NASA image

The black hole in question is thought to be super massive — about 1 million times the mass of the sun. Accordingly, it has an immensely powerful gravitation pull. So when an unassuming star traversed near this black hole, it began to rip the star apart. This dramatic moment is called a tidal disruption event, or flare.

"It's just gravity — but gravity in an extreme situation," Chris Fryer, an astrophysicist at Los Alamos National Laboratory who had no involvement in the study, said in an interview.

These tidal disruption flares are critical to understanding the nature, and spin, of black holes that are actively consuming stars. (Full Story)

The meteor shower that brought Tunguska is due in June

Aftermath of the Tunguska impact.

Physicist Mark Bosloughof Los Alamos National Laboratory recently presented, at the American Geophysical Union fall meeting, a new analysis of the tree-fall pattern in the Tunguska area. It suggests that the rock may have arrived during the annual Beta Taurid meteor shower. The next one's in June 2019. (There's another Taurid shower each October.) A quote from the presentation: "If the Tunguska object was a member of a Beta Taurid stream … then the last week of June 2019 will be the next occasion with a high probability for Tunguska-like collisions or near misses."

Neither Bosloughof of anyone else predicts a Tunguska-style event in June, but if the new calculations are correct, it's just the meteor shower in which it probably arrived back in 1908. According to physicist Peter Brown, who presented the new analysis with Bosloughof, "This is not something that should be keeping you up at night." (Full Story)

Researchers solve mystery of Yemen cholera epidemic

Computer generated depiction of a cholera organism, CDC image.

Through the use of genomic sequencing, scientists at the Wellcome Sanger Institute and Institut Pasteur estimate the strain of cholera causing the current outbreak in Yemen—the worst cholera outbreak in recorded history—came from Eastern Africa and entered Yemen with the migration of people in and out of the region.

To understand the nature of the strain of bacteria behind these devastating cholera outbreaks, researchers from the Wellcome Sanger Institute, now based at Los Alamos National Laboratory, Institut Pasteur and their collaborators sequenced the genomes of Vibrio cholerae from cholera samples collected in Yemen and nearby regions.(Full Story)

Bizarre hum near Vancouver Island could predict the next deadly earthquake & tsunami

Coast of Vancouver Island, from Advocator.

Off the coast of Vancouver Island, the huge undersea Juan de Fuca tectonic plate is sliding under the large North American plate. In other words, the west coast of Canada is at high risk of a massive earthquake and a tsunami.

Since 1700, Cascadia has been quiet, but it seems that every year or so, there’s a slow slip when the North American plate lurches over the Juan de Fuca plate.

“This slip has been observed in advance of major earthquakes, which suggests it might be part of the process that causes them,” according to a new paper by Bertrand Rouet-Leduc and Claudia Hulbert of the Los Alamos National Laboratory in New Mexico. (Full Story)

'Realistic' new model points the way to more efficient and profitable fracking

Despite the industry's growth, much of the fracking process remains mysterious. Because fracking happens deep underground, researchers cannot observe the fracture mechanism of how the gas is released from the shale.

"This work offers improved predictive capability that enables better control of production while reducing the environmental footprint by using less fracturing fluid," said Hari Viswanathan, computational geoscientist at Los Alamos National Laboratory. "It should make it possible to optimize various parameters such as pumping rates and cycles and changes of fracturing fluid properties such as viscosity. This could lead to a greater percentage of gas extraction from the deep shale strata, which currently stands at about five percent and rarely exceeds 15 percent." (Full Story)

New LANL director: Community relations is a priority

Thomas Mason, LANL photo

The new director of Los Alamos National Laboratory says that, along with the lab’s nuclear weapons missions, its science and engineering efforts, and upgrading operational functions, community relations will be a key piece of LANL’s agenda under new operator Triad National Security, LLC.

“Because if you lose the trust and confidence of the communities in which you’re located, you’ll find pretty quickly that you can’t get anything done, because you lose the support that you need,” said Thomas Mason, a former director at Oak Ridge National Laboratory in Tennessee who took over at LANL on Nov. 1. (Full Story)

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