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Mar. 31, 2012
Volume: III
Number: 13
 
National Society of Black Physicists    African Physical Society    South African Institute of Physics   African Astronomical Society   
 
 
Ultrafast laser pulses shed light on elusive superconducting mechanism
PhysOrg    Share    Share on FacebookTwitterShare on LinkedinE-mail article
In experiments reported in Science, an international team used ultrafast laser pulses to excite electrons in a prototypical copper-oxide superconductor. As the material's electrons relaxed back to an equilibrium state, they released their excess energy via deformation of the superconductor's atomic lattice (phonons) or perturbation of its magnetic correlations (spin fluctuations). The researchers were able to capture very fine-grained data on the speed of the relaxation process and its influence on the properties of the superconducting system, showing that the high-critical temperature of these compounds can be accounted for by purely electronic (magnetic) processes. "This breakthrough in the understanding of the puzzling properties of copper-oxides paves the way to finally solving the mystery of high-temperature superconductivity," says the paper's lead author Claudio Giannetti, a researcher with Italy's Università Cattolica del Sacro Cuore and visiting professor at UBC's Quantum Matter Institute. More



Lightning strikes produce free neutrons, and we're not sure how
Ars Technica    Share    Share on FacebookTwitterShare on LinkedinE-mail article
In 1985, scientists in the Soviet Union observed that whenever a thunder storm passed over their neutron detector, they would see increased neutron fluxes. Since then, scientists have put forward a couple of potential explanations for the observed flux. One was that the high fields generated during lightning strikes was modifying the trajectories of muons from cosmic ray showers. The second was that the gamma rays emitted during the lightning strike generated neutrons. Neither of these explanations have satisfactorily explained the data. In a paper in Physical Review Letters a team of Russian physicists report the first measurement of an extraordinarily high flux of low-energy neutrons generated during thunderstorms. The surprising result is that the new data show that up to 5,000 neutrons per cubic meter are produced every second by lightning strikes. Previous results had assumed that each detection event corresponded to a single neutron. The problem, for the second explanation at least, is that to generate this observed neutron flux it would take about 10 million gamma ray photons m-3s-1. Unfortunately, lightning strikes only generate a tiny fraction of that. More



Clocking an accelerating universe: 1st results from BOSS
Lawrence Berkeley Laboratory    Share    Share on FacebookTwitterShare on LinkedinE-mail article
In two papers available on arXiv (1, 2), the Baryon Oscillation Spectroscopic Survey, the largest component of the third Sloan Digital Sky Survey (SDSS-III), has announced the most accurate measurement yet of the distance scale of the universe during the era when dark energy turned on. Baryon acoustic oscillation measures the angle across the sky of structures of known size, the peaks where galaxies cluster most densely in the network of filaments and voids that fill the universe. BOSS' first major cosmological results establish the accurate three-dimensional positions of 327,349 massive galaxies across 3,275 square degrees of the sky, reaching as far back as redshift 0.7 — the largest sample of the universe ever surveyed at this high density. BOSS' data on galaxy clustering and redshifts can be applied not only to BAO but also to a separate technique called "redshift space distortions" — a direct test of gravity that measures how fast neighboring galaxies are moving together to form galaxy clusters. General Relativity predicts how fast galaxies should be moving toward one another in galaxy clusters, and, in the aggregate, how fast the structure of the universe should be growing. Any departure from its predictions would mean the theory is flawed. More

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New density waves in fermion liquids discovered by neutron scattering
R & D Magazine    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Scientists working at the Institut Laue-Langevin have reported in Nature the results of neutron scattering investigations of 2-D fermionic liquid 3He, and discovered a new type of very short wavelength density wave also known as zero-sound oscillations. The zero sound modes turned out to be far longer lived in this two-dimensional fluid than those seen during previous experiments in bulk liquids, where they were strongly damped. The researchers believe that if this type of high-frequency density oscillation is seen in another fermion liquid, composed of electrons, this could be a mechanism for high-temperature superconductivity. More

2012 Quadrennial Physics Congress
The 2012 Quadrennial Physics Congress, hosted by Sigma Pi Sigma, the physics honor society. This meeting will take place Nov. 8-12 in Orlando, Fla., and will center on the theme Connecting Worlds Through Science & Service. Undergraduates, practicing physicists and physics alumni from a broad spectrum of career paths will gather together to address the interconnectivity of the modern world and what it means to science.

The Congress will feature talks by distinguished scientists such as Dr. John Mather, Physics Nobel Laureate; Freeman Dyson, acclaimed scientist and author; Dr. John Grunsfeld, astronaut and former chief scientist of NASA; Dr. Jocelyn Bell Burnell, world-class astrophysicist known for discovering pulsars, and many more.


NSBP member, Hakeem Oluseyi, selected to be a 2012 TED Global Fellow
NSBP    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Florida Institute of Technology professor, Hakeem Oluseyi, has been selected to be 2012 TED Global Fellow. He will participate in the TED conference in Edinburgh, Scotland, June 25-29. Dr. Oluseyi is an astrophysicist, inventor and science educator whose research focuses on measuring the structure and evolution of the Milky Way galaxy and characterizing new planetary systems. Oluseyi has lectured widely in the U.S. and Africa. He was one of the founding members of the African Astronomical Society and is currently an officer of the National Society of Black Physicists. TED is a nonprofit devoted to Ideas Worth Spreading. It started out (in 1984) as a conference bringing together people from three worlds: technology, entertainment, design. Past TED Fellows include CERN's Bilge Demirkoz, Harvard's Michelle Borkin and NASA's Lucianne Walkowicz. More



Particle-wave duality demonstrated with largest molecules yet
Ars Technica    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Researchers have successfully performed a quantum interference experiment with phthalocyanine (C32H18N8) and its derivative molecules (C48H26F24N8O8). These are the largest molecules in which quantum interference has been observed. In an experiment that approached the regime where macroscopic and quantum physics overlap, the team fired molecules composed of over 100 atoms at a barrier with slits designed to minimize molecular interactions, and observed the build-up of an interference pattern. After passing through the slits, the molecules' positions were recorded using fluorescence microscopy, which has both sufficient spatial resolution and fast response to detect when and where the molecules arrive. The researchers observed the particle nature of the molecules in the form of individual light spots that appeared singly in the fluorescent detector as they arrived. But, over time, these spots formed an interference pattern due to the molecules' wavelike character. The researchers assert that no other explanation but quantum interference can account for the pattern that appears in the fluorescent detector. The work is published in Nature Nanotechnology. More

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US physicists fight to save neutrino experiment
Nature    Share    Share on FacebookTwitterShare on LinkedinE-mail article
The future of the Long-Baseline Neutrino Experiment was thrown into jeopardy when officials at the U.S. Department of Energy announced that they were reluctant to fund it in its current form, and asked for the development of a more affordable and phased approach. The LBNE would measure the rates at which neutrinos and antineutrinos oscillate between their three different types, or flavors, and so test a hypothesized asymmetry between matter and antimatter. At a cost of between $1.2 billion and $1.5 billion, the LBNE was expected to come online in 2022–2024, and to have a construction budget peaking at roughly $200 million per year. But that is now considered too great a slice of the DOE's annual high-energy physics budget, which was cut by $6 million to $757 million in President Barack Obama's 2013 budget request for the DOE Office of Science. More



Star explodes and turns inside out
Science Daily    Share    Share on FacebookTwitterShare on LinkedinE-mail article
A new X-ray study of the remains of an exploded star, reported in the Astrophysical Journal, indicates that the supernova that disrupted the massive star may have turned it inside out in the process. Using very long observations of Cassiopeia A (or Cas A), a team of scientists has mapped the distribution of chemical elements in the supernova remnant in unprecedented detail. This information shows where the different layers of the pre-supernova star are located 300 years after the explosion, and provides insight into the nature of the event. Interpretations of the X-ray observations in the context of hydrodynamical models for the evolution of post-supernova material flow suggest that the ejected materials from the star were subjected to multiple secondary shocks following reverse shock interaction with hydrodynamic instabilities. More

International Conference of Physics Students
The International Conference of Physics Students is an annual conference of the International Association of Physics Students. Usually, up to 400 students from all over the world attend the event. The 2012 ICPS will be held in the Netherlands in Aug. 4-10. During this week, approximately 400 students from around the world can enjoy lectures from top-class physicists, trips to scientific institutions and cultural excursions. Registration opens in February at www.icps2012.com.


Still no signs of antihelium in cosmic rays
American Physical Society    Share    Share on FacebookTwitterShare on LinkedinE-mail article
It is a fundamental question in cosmology whether or not the universe is globally baryon symmetric. Most of our universe appears to be made of matter rather than antimatter. But isolated pockets of antimatter could exist in the cosmos. However, new data from a balloon-borne experiment make this possibility seem less and less likely. The Balloon-borne Experiment with Superconducting Spectrometer, a joint Japan-U.S. project, has been looking for the antimatter equivalent of helium nuclei in cosmic rays. But as the collaboration reports in Physical Review Letters, such nuclei have not been detected, putting the most stringent limits yet on the antihelium abundance in Earth’s cosmological neighborhood. More

Gravitational Wave Astronomy Workshop
The South African Institute of Physics in collaboration with U.S.-based Laser Interferometer Gravitational Wave Observatory will be hosting a workshop from May 31-June 1 to promote gravitational wave astronomy in Africa. The workshop will cover an overview of the field, including laser interferometry, data analysis, numerical relativity, approximate analytic methods, source modeling and astrophysical implications, pulsar timing and current African activity in gravitational wave astronomy.


Spider silk conducts heat better than copper
Wired    Share    Share on FacebookTwitterShare on LinkedinE-mail article
As detailed in a paper in Advanced Materials, spider silk conducts heat better than silicon and copper, 1,000 times better than woven silkworm silk and 800 times better than other organic tissues. Spider silk's thermal conductivity is also increased by 20 percent when it was stretched to its 20 percent limit. Most materials lose thermal conductivity when stretched. These unusual properties are down to the defect-free molecular structure of spider silk, including proteins that contain nanocrystals and the spring-shaped structures connecting the proteins. This discovery could open a door to using spider silk to create flexible, heat-dissipating parts for electronics, better clothes for hot weather and bandages that don't trap heat. However, more research is needed to fully understand why spider silk is so good at conducting heat. More



Experts debate public access to scholarly research at House hearing
The Chronicle of Higher Education    Share    Share on FacebookTwitterShare on LinkedinE-mail article
A panel of five experts recently debated the merits of open-access publishing models in front of a U.S. House of Representatives subcommittee, weighing the implications of a proposed bill that would require the results of federally funded research to be made publicly available within six months of publication. The panel included Fred Dylla, the CEO of the American Institute of Physics, who testified that the current system of scholarly communications is working. He warned that proposals that "significantly distort" the established order by imposing one-size-fits-all mandates would diminish scientific research and do irreparable harm to small publishers who provide important services. Such proposal is the Federal Research Public Access Act, was introduced in February in the House and Senate. It surfaced for the third time since 2006, and stands as an open-access alternative to the failed Research Works Act. More



Engage to Excel: A call to action by the White House
Physics Today    Share    Share on FacebookTwitterShare on LinkedinE-mail article
In a Science commentary, physicist S. James Gates Jr. and chemist Chad Mirkin, members of the President's Council of Advisors on Science and Technology, argue for "approaches that engage students actively." In the United States, over 60 percent of students who enter college intending to major in a STEM field fail to graduate with a STEM degree. Reducing this dropout rate is the focus of a report PCAST released in February, called "Engage to Excel: Producing One Million Additional College Graduates with Degrees in Science, Technology, Engineering, and Mathematics." This report proposes five "overarching recommendations to transform undergraduate STEM education during the transition from high school to college" and during the first two undergraduate years. These issues as it relates to closures of small STEM programs were incidentally an agenda item at the recent AIP Assembly of Officers meeting. More





National Society of Black Physicists jobs board postings
NSBP    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Advanced Topics in Astrostatistics
Assistant In Materials Instrumentation and Facilities- National High Magnetic Field Laboratory
Duncan Instructor
Introductory Course Instructor and Manager
Summer Intern
IAU Office of Astronomy for Development: Internship Opportunity
Postdoctoral Associate
Entrepreneurship for Scientists and Engineers in East Africa
Director, South African Astronomical Observatory
Marshall REU in Scientific Computing
Research in Sustainable Energy for sub-Saharan Africa
Notre Dame Physics REU Program
Tenure Track (Open Rank) Faculty Position - Stony Brook Center for Science and Mathematics Education
HBCU STEM Fellowship Program
National Astrophysics and Space Science Programme
Postdoctoral Research Associate Positions




Latest research from Physica Scripta
IOP Journal    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Approximate spin and pseudospin solutions to the Dirac equation for the inversely quadratic Yukawa potential and tensor interaction

Decoherence without dissipation due to fermionic bath

Elastic positron scattering by radon and radium atoms

On the shape of a lightweight drop on a horizontal plane

Multisoliton solutions to the modified nonlinear Schrödinger equation with variable coefficients in inhomogeneous fibers
More

Latest research from Optics Express
Optics Express    Share    Share on FacebookTwitterShare on LinkedinE-mail article
Vanadium dioxide based plasmonic modulators

Electrically generated unidirectional surface plasmon source

Dark current reduction of Ge photodetector by GeO_2 surface passivation and gas-phase doping

Evaluation of breast tumor margins in vivo with intraoperative photoacoustic imaging

Microbubble generation using fiber optic tips coated with nanoparticles
More

 

 
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