Laser-driven Hohlraums filled with gas at lower densities (0.6 mg/cc) have higher efficiency compared to original ≥ 0.96 mg/cc fill because of reduced backscatter losses [Hall et al., Phys. Plasma…
Sparse regression for plasma physics
Posted in physics
Many scientific problems can be formulated as sparse regression, i.e., regression onto a set of parameters when there is a desire or expectation that some of the parameters are exactly zero or do not substantially contribute. This includes many problems in signal and image processing, system identification, optimization, and parameter estimation methods such as Gaussian process regression. Sparsity facilitates exploring high-dimensional spaces while finding parsimonious and interpretable solutions. In the present work, we illustrate some of the important ways in which sparse regression appears in plasma physics and point out recent contributions and remaining challenges to solving these problems in this field. A brief review is provided for the optimization problem and the state-of-the-art solvers, especially for constrained and high-dimensional sparse regression.
Magneto-inertial fusion concepts, such as the magnetized liner inertial fusion (MagLIF) platform[M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)], constitute an alternative path for achiev…
Scientists have precisely measured the masses of 19 neutron-rich nuclei, discovering a new isotope of uranium in the process.
Spinning Heat in Reverse
Posted in futurism
Researchers have attained a 100-fold increase in the accuracy of a molecular clock that could serve as a terahertz-frequency standard and as a platform for investigating new physics.
Having more tools helps; having the right tools is better. Utilizing multiple dimensions may simplify difficult problems—not only in science fiction but also in physics—and tie together conflicting theories.
For example, Einstein’s theory of general relativity —which resides in the fabric of space-time warped by planetary or other massive objects—explains how gravity works in most cases. However, the theory breaks down under extreme conditions such as those existing in black holes and cosmic primordial soups.
An approach known as superstring theory could use another dimension to help bridge Einstein’s theory with quantum mechanics, solving many of these problems. But the necessary evidence to support this proposal has been lacking.
Researchers at University of Tokyo, JTS PRESTO, Ludwig Maximilians Universität and Kindai University recently demonstrated the modulation of an electron source by applying laser light to a single fullerene molecule. Their study, featured in Physical Review Letters, could pave the way for the development of better performing computers and microscopic imaging devices.
“By irradiating a sharp metallic needle with femtosecond pulses, we had previously demonstrated optical control of electron emission sites on a scale of approximately 10 nm,” Hirofumi Yanagisawa, one of the researchers who carried out the study, told Phys.org. “The optical control was achieved using plasmonic effects, but it was technically difficult to miniaturize such an electron source using the same principle. We were seeking a way to miniaturize the electron source and we hit upon the idea of using a single molecule and its molecular orbitals.”
Yanagisawa and his colleagues set out to realize their idea experimentally using electrons emitted from molecules on a sharp metallic needle. However, they were well-aware of the difficulties they would encounter, due to unresolved difficulties associated with the use of electron emissions from molecule-covered needles.
Anti AI / AI ethics clowns now pushing.gov for some criminalization, on cue.
A nonprofit AI research group wants the Federal Trade Commission to investigate OpenAI, Inc. and halt releases of GPT-4.
OpenAI “has released a product GPT-4 for the consumer market that is biased, deceptive, and a risk to privacy and public safety. The outputs cannot be proven or replicated. No independent assessment was undertaken prior to deployment,” said a complaint to the FTC submitted today by the Center for Artificial Intelligence and Digital Policy (CAIDP).
Calling for “independent oversight and evaluation of commercial AI products offered in the United States,” CAIDP asked the FTC to “open an investigation into OpenAI, enjoin further commercial releases of GPT-4, and ensure the establishment of necessary guardrails to protect consumers, businesses, and the commercial marketplace.”
In Sparks of Artificial General Intelligence: Early experiments with GPT-4.
In chatbots we trust.