Waves & Packets
Mar. 2, 2013

Astronomers capture image of planet formation for the first time
European Southern Observatory
Research on planet formation has mostly involved theoretical models and computer simulations. According to the most accepted theory of planet formation, giant planets grow by capturing some of the gas and dust that remains after the formation of a star. Astronomers using ESO's Very Large Telescope in Chile have obtained what is likely the first direct observation of a forming planet still embedded in a thick disc of gas and dust. This newly observed body, as yet still a planet candidate, is orbiting the young star HD 100546. This discovery, reported in Astrophysical Journal Letters, will allow astronomers to test the current theories against an observable target. Follow-up observations will discern whether or not this is a new planet forming, or an old planet in a new orbit; or if the observations are real at all. If confirmed to be an actual planet, observations of a planet in the act of forming will greatly improve our understanding planet formation, disc hydrodynamics and more.More

Carbon-nanotube transistors detect disease biomarkers
New experiments have demonstrated that CNTs can detect minute quantities of biomarkers of diseases in less time than conventional methods. From immunology we know that it is possible to raise an antibody that binds specifically to foreign molecules (antigens). This is the basis of molecular immunity, and is exploited in biomarker assay methods. If the antibodies are engineered in some way, e.g., attached to some fluorescent molecule, and then exposed to some sample containing an unknown concentration of antigens, the fluorescent antibody-antigen complexes give not only a qualitative but also a quantitative measure of antigens in the sample. Now suppose one attaches the antibodies to CNT on a silicon chip, and that upon antibody-antigen binding the electrical properties of the chip change. This has been done by a group of physicists, and they have built systems to detect biomarkers of lyme disease, salmonella and prostate cancer. These CNT-based sensors have the virtues of being more sensitive, faster and cheaper than current molecular-tagging immunoassay techniques.More

Cherenkov emitters show promise for cancer therapy
Physics World
Gold-198 undergoes beta decay and emits a fast-moving electron, which in turn creates Cherenkov radiation in the form of visible and NIR light. Radiation at these wavelengths (700–900 nm) can penetrate deeply into soft biological tissue and so is perfect for optical imaging based on photoacoustic and optical-coherence tomography. Hollow gold nanocages are biologically inert but can absorb and scatter radiation in the near-infrared region of the electromagnetic spectrum. The heavier isotope of gold does not alter the physiochemical properties of these nanostructures. Combining these points, a team of researchers has demonstrated that Au-138 nanocages are stable, they accumulate in tumors, and that the beta-decay emission can be used to image tumors in live mice. This imaging method has the benefit of not requiring an external excitation source. This work is reported in Nano Letters. More

Spin rate of black hole definitely measured by NuStar and XMM-Newton
Astronomers using two X-ray space observatories, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's XMM-Newton, have teamed up to measure definitively, for the first time, the spin rate of a black hole. They determined that the supermassive black hole at the center of the galaxy NGC 1365 is spinning almost as fast as Einstein's theory of gravity will allow. The spin rate of a black hole tells a lot about how it formed. Fast spinning black holes formed quickly, while slower ones formed more slowly. These recent observations, reported in Nature, lean on the fact that as a black hole consumes mass, the process emits X-radiation from the inner edge of the accretion disc. Fast spinning black holes will have X-ray emissions that are more gravity-effected, i.e., red-shifted, than those from slow spinning ones. But the X-rays are scattered and obscured by the disc itself, so astronomers have to discern red-shift due to the effects of spinning rate, from those due to matter in the disc. The 19-month old NuStar enabled this step due to its unique sensitivity in the 3–80 keV energy range where the disc scattering and absorption effects are less pronounced.More

Noise-induced quantum coherence increases photosynthetic yield
The presence of quantum coherence in photosynthesis in plants, bacteria and marine algae at ambient temperatures is well-established. Two such effects that appeared to be unrelated — enhanced solar cell efficiency and population oscillations in photosynthetic antennae — have been detected in natural and artificial light-harvesting systems. Recently, however, in a paper appearing in the Proceedings of the National Academy of Sciences of the United States of America, scientists have shown that these effects are, in fact, deeply connected, i.e., they both arise from the same population–coherence coupling term that is noise-induced and does not require coherent light — meaning that these effects will take place under the incoherent conditions of natural solar excitation. Researchers were able to demonstrate that both effects operate as quantum heat engines that convert solar photon energy into useful work. They predict that when coexisting they can potentially increase charge separation yield by 27 percent. Their findings suggest the viability of artificial solar energy devices based on biomimetic quantum heat engine architecturesMore

Spectroscopy of gaseous water dimers: A key step towards understanding solar absorption and atmospheric chemistry
American Physical Society
Models of atmospheric absorption that only take into account rotational and vibration-rotational transitions of single-molecules do not match up with actual measurements of the atmosphere's absorption spectrum. One possibility is that water dimers and larger water clusters act as sources of excess absorption. The idea has been intensely debated for over four decades, with recent work reported in Physical Review Letters suggesting that water dimers are involved in both the radiation balance and chemistry of the atmosphere. To perform spectroscopy specifically on water dimers, researchers in Russia developed millimeter wave spectrometer with a variable resonator that optimally selects for a particular frequency of radiation depending on the separation between the mirrors. Prior predictions indicated that water dimers' rotational transitions would lie between 100–150 GHz, and the researchers were able to tune their resonator to detect these transitions. Based on their measurement, the authors estimate that the relative abundance of the dimers in the equilibrium vapor is roughly 1×10−3. If this measurement is confirmed by other experiments, it will constitute the first detection of water dimers under ambient temperature equilibrium conditions. These results are of fundamental interest in molecular physics, and also of applied interest in Earth sciences. More

Astronomers find unexplained 'structure' in black hole accretion disk
Using the Swift Burst Alert Telescope astronomers have found optical evidence of a previously unknown structure in the accretion disk of binary system consisting of a star and a black hole that has a mass greater than three times that of the Sun. The structure is at the outer portion of the accretion disk and causes an optical dimming of the system — one that cannot be explained by the stars' orbit around the system's center of mass. Moreover the optical dimming does not have x-ray counterparts. Researchers do not know what the structure is, but it is best explained by the presence of an obscuring toroidal structure moving outward in a wave in the inner disk. Astronomers believe this particular system is being seen at very high inclination, and that this relative orientation towards Earth is actually why we cannot see many other black holes that should be evident in our galaxy. These observations are reported in Science. More

Van Allen probes reveal new third radiation belt around Earth
The so-called Van Allen belt, consisting of rings of high-energy relativistic electrons held around the Earth by the magnetosphere, was discovered 50 years ago. The rings were thought to be just two in number. But new observations using NASA's Relativistic Electron Proton Telescope (REPT) have discovered an extra, third ring. As detailed in a Science paper, researchers found that the third ring persisted over a four week period, changing only gradually until it abruptly disappeared. While the inner ring of the Van Allen belt and the new ring showed very little change over the four weeks, the more distant part of the outer Van Allen belt seemed to be changing significantly throughout the same period. When the new ring disappeared, almost the entire electron population in the outer-zone had disappeared too. Researchers do not know if what caused the third ring to appear and disappear, or if it has a regular periodic cycle. They speculate that the ring was destroyed by a coronal mass ejection. Previous studies have shown that the outer-zone electron populations are much more susceptible to space weather. More

Pulse-probe spectroscopy, transient charge-density waves and superconducting cuprates
Brookhaven National Lab
Static order in charge and spin exists in cuprate superconductors. But observations of transient waves of this type have heretofore not been accessible. But as detailed in a Nature Materials paper, a team of physicists from BNL and MIT has developed an ultra-fast pulse-probe technique to directly observe charge-density waves. Applying the technique to epitaxially-grown cuprates, the team found that in underdoped La1.9Sr0.1CuO4, transient (2 ps) charge-density waves were present at T=5K, well below the superconducting transition temperature of 26K. The transient time decreased to 0.5 ps at T=100K. But in the optimally doped case, La1.84Sr0.16CuO4, where the superconducting transition temperature is maximized for this material, there were no transient charge-density waves detected at any temperature. This suggests that charge-density wave formation is an independent of superconductivity and is likely a competing instability. Moreover, these experiments suggest that suppressing transient charge-density waves might work to increase the temperature limits of superconductivity.More

Physicists and astronomers encouraged to participate in Congressional Visits Day, March 12-13
Science-Engineering-Technology Working Group
The Congressional Visits Day is a two-day annual event that brings scientists, engineers, researchers, educators and technology executives to Washington, D.C., to raise visibility and support for science, engineering and technology. Uniquely multi-sector and multi-disciplinary, the CVD is coordinated by coalitions of companies, professional societies, including American Astronomical Society, the American Physical Society and the National Society of Black Physicists, as well as several educational institutions. During the event the Science-Engineering-Technology Working Group bestows the George E. Brown, Jr. Award for S-E-T Leadership upon Members of Congress who have been especially effective in S&T advocacy and leadership. CVD participants are encouraged visit their Representative in the House and their two Senators so that they can hear about the importance of S&T directly from one of their constituents. The event is open to all who believe that science and technology comprise the cornerstone of our Nation's future.More

Former NSBP president, Sekazi Mtingwa, publishes new e-book, 'Introductory Physics II: On the Duality of Electric and Magnetic Phenomena.'
This new electronic textbook is designed for calculus-based, freshman/sophomore E&M courses and is available for purchase at triseedconsultants.com. The lectures offer a new way of introducing E&M concepts by continually showing the parallel between the electric and magnetic sectors of the physics. The course starts with an introduction to special relativity and uses it to show how the existence of electric fields must be accompanied by magnetic fields. From there, practically all electric and magnetic phenomena are introduced together, as opposed to spending the first half of the course studying electric phenomena and devoting the second half to studying magnetic phenomena, as is usually done. For most students, this latter approach loses the beauty of the unification of electricity and magnetism. More

Increase your options for graduate or REU program admissions
The NSBP GradApps and REUApps services are open to all students and allows them to upload all the elements of an admissions application, including academic and work history, transcripts, letters of recommendation and a personal statement. Graduate and REU programs can subscribe to these databases to increase the programs' applicant pool, while at the same time allowing students can put their credentials in front of more programs than to which they would otherwise apply. More

National Society of Black Physicists jobs board postings
Postdoctoral Fellowship — Stanford Molecular Imaging Scholars Program
Physics Academic Coordinator I/Lecturer
Summer Undergraduate Researcher
REU summer program on complex materials
REU Student
National Radio Astronomy Observatory Research Experience for Undergraduates
Postdoctoral Research Associate Positions More

Latest research from Physics Education
IOP Publishing
Antihydrogen in a bottle

Seeing sound waves: a simple method to see sound waves travelling through the open air

Sticky physics of joy: on the dissolution of spherical candies

Supersonic freefall—a modern adventure as a topic for the physics class

An interdisciplinary school project using a Nintendo Wii controller for measuring car speed


Latest research from Brazilian Journal of Physics
The Myth of Academic Excellence and Scientific Curiosity

Time Periodicity and Dynamical Stability in Two-Boson Systems

The Influence of Hyperons and Strong Magnetic Field in Neutron Star Properties

Temperature-Dependent Current–Voltage (I–V) and Capacitance–Voltage (C–V) Characteristics of Ni/Cu/n-InP Schottky Barrier Diodes