All Optical Timing Extraction with Frequency Division using a Twin Section Laser Diode

All-optical timing extraction from a coded line signal with division of the extracted clock frequency is demonstrated using a single twin-section self-pulsating laser diode. Either the bit-rate clock or a submultiple of the bit-rate clock can be extracted, depending only on the dc biases applied to the self-pulsating laser diode. Timing extraction is carried out for the first time without optical injection locking of the self-pulsating laser diode by the optical data source

Quantum oscillations and a non-trivial Berry phase in the noncentrosymmetric superconductor BiPd

We report the measurements of de Haas-van Alphen (dHvA) oscillations in the noncentrosymmetric superconductor BiPd. Several pieces of a complex multi-sheet Fermi surface are identified, including a small pocket (frequency 40 T) which is three dimensional and anisotropic. From the temperature dependence of the amplitude of the oscillations, the cyclotron effective mass is ($0.18$ $\pm$ 0.1) $m_e$. Further analysis showed a non-trivial $\pi$-Berry phase is associated with the 40 T pocket, which strongly supports the presence of topological states in bulk BiPd and may result in topological superconductivity due to the proximity coupling to other bands.Comment: 5 pages, 3 figure

Mutations in shaking-B prevent electrical synapse formation in the Drosophila giant fiber system

The giant fiber system (GFS) is a simple network of neurons that mediates visually elicited escape behavior in Drosophila. The giant fiber (GF), the major component of the system, is a large, descending interneuron that relays visual stimuli to the motoneurons that innervate the tergotrochanteral jump muscle (TTM) and dorsal longitudinal flight muscles (DLMs). Mutations in the neural transcript from the shaking-B locus abolish the behavioral response by disrupting transmission at some electrical synapses in the GFS. This study focuses on the role of the gene in the development of the synaptic connections. Using an enhancer-trap line that expresses lacZ in the GFs, we show that the neurons develop during the first 30 hr of metamorphosis. Within the next 15 hr, they begin to form electrical synapses, as indicated by the transfer of intracellularly injected Lucifer yellow. The GFs dye-couple to the TTM motoneuron between 30 and 45 hr of metamorphosis, to the peripherally synapsing interneuron that drives the DLM motoneurons at approximately 48 hr, and to giant commissural interneurons in the brain at approximately 55 hr. Immunocytochemistry with shaking-B peptide antisera demonstrates that the expression of shaking-B protein in the region of GFS synapses coincides temporally with the onset of synaptogenesis; expression persists thereafter. The mutation shak-B2, which eliminates protein expression, prevents the establishment of dye coupling shaking-B, therefore, is essential for the assembly and/or maintenance of functional gap junctions at electrical synapses in the GFS

Monopoly power of the medical school market and high incomes of U.S. physicians

We expect the incomes of physicians to remain high in the next decades. Using the latest published physician income data (2015) we calculated the weighted median income of U.S. physicians and the net present value (NPV) of an investment in physician education. We estimated the NPV assuming that the physicians training began in 2007 and their practice would commence in 2015. We estimated the NPV of the lifetime earnings of a physician based on the median income of all physicians in the sample to be between $7.1 and$7.3 million. This finding of high NPV’s is consistent with almost all earlier studies of this kind. Physicians continue to experience relatively high incomes and very slow increases in the number of new graduates. We expect an excess demand for positions in medical colleges to continue. Our findings with respect to the incomes of non-primary physicians (surgeons, radiologist and cardiologists), indicate will continue to be much higher than those of primary physicians. There are strong evidence suggesting this is because of blockages in physician residency openings in these non-primary fields of medicine.peer-reviewe

Self-Pulsating Semiconductor Lasers: Theory and Experiment

We report detailed measurements of the pump-current dependency of the self-pulsating frequency of semiconductor CD lasers. A distinct kink in this dependence is found and explained using rate-equation model. The kink denotes a transition between a region where the self-pulsations are weakly sustained relaxation oscillations and a region where Q-switching takes place. Simulations show that spontaneous emission noise plays a crucial role for the cross-over.Comment: Revtex, 16 pages, 7 figure

Vapor Generation in a Nanoparticle Liquid Suspension Using a Focused, Continuous Laser

This letter discusses experimentation with optically induced phase change in nanoparticle liquid suspensions-commonly termed nanofluids. Four different types of nanofluids at five concentrations were exposed to a similar to 120 mW, 532 nm laser beam to determine the minimum laser flux needed to create vapor. Laser irradiance was varied between 0-770 W cm(-2). While the experiments were simple, they involved many complex, interrelated physical phenomena, including: subcooled boiling, thermal driven particle/bubble motion, nanoparticle radiative absorption/scattering, and nanoparticle clumping. Such phenomena could enable novel solar collectors in which the working fluid directly absorbs energy and undergoes phase change in a single step. c 2009 American Institute of Physics. [doi: 10.1063/1.3250174