High-Order Harmonic Generation and Molecular Orbital Tomography: Characteristics of Molecular Recollision Electronic Wave Packets

We investigate the orientation dependence of molecular high-order harmonic generation (HHG) both numerically and analytically. We show that the molecular recollision electronic wave packets (REWPs) in the HHG are closely related to the ionization potential as well as the particular orbital from which it ionized. As a result, the spectral amplitude of the molecular REWP can be significantly different from its reference atom (i.e., with the same ionization potential as the molecule under study) in some energy regions due to the interference between the atomic cores of the molecules. This finding is important for molecular orbital tomography using HHG[Nature \textbf{432}, 867(2004)].Comment: 4 pages, 4 figure

The human kindness curriculum: An innovative preclinical initiative to highlight kindness and empathy in medicine.

BackgroundPrior studies have shown a marked drop in empathy among students during their third (clinical) year of medical school. Curricula developed to address this problem have varied greatly in content and have not always been subjected to validated measures of impact.MethodsIn 2015, we initiated a Human Kindness (HK) curriculum for the initial 2 years of medical school. This mandatory 12-h curriculum (6 h/year) included an innovative series of lectures and patient interactions with regard to compassion and empathy in the clinical setting. Both quantitative (Jefferson Scale of Empathy [JSE]) and qualitative data were collected prospectively to evaluate the impact of the HK curriculum.ResultsIn the initial Pilot Year, neither 1st (Group 1) nor 2nd (Group 2) year medical students showed pre-post changes in JSE scores. Substantial changes were made to the curriculum based on faculty and student evaluations. In the following Implementation Year, both the new 1st (Group 3) and the now 2nd year (Group 4) students, who previously experienced the Pilot Year, showed significant improvements in post-course JSE scores; this improvement remained valid across subanalyses of gender, age, and student career focus (e.g., internal medicine, surgery, etc.). Despite the disappointingly flat initial Pilot Year JSE scores, the 3rd year students (Group 2) who experienced only the Pilot Year of the curriculum (i.e., 2nd year students at the time of the Pilot Year) had subsequent JSE scores that did not show the typical decline associated with the clinical years. Students generally evaluated the HK curriculum positively and rated it as being important to their medical education and development as a physician.DiscussionA required preclinical curriculum focused on HK resulted in significant improvements in medical student empathy; this improvement was maintained during the 1st clinical year of training

An Ultra Low Mass and Small Radius Compact Object in 4U 1746-37?

Photospheric radius expansion (PRE) bursts have already been used to constrain the masses and radii of neutron stars. RXTE observed three PRE bursts in 4U 1746-37, all with low touchdown fluxes. We discuss here the possibility of low mass neutron star in 4U 1746-37 because the Eddington luminosity depends on stellar mass. With typical values of hydrogen mass fraction and color correction factor, a Monte-Carlo simulation was applied to constrain the mass and radius of neutron star in 4U 1746-37. 4U 1746-37 has a high inclination angle. Two geometric effects, the reflection of the far side accretion disc and the obscuration of the near side accretion disc have also been included in the mass and radius constraints of 4U 1746-37. If the reflection of the far side accretion disc is accounted, a low mass compact object (mass of $0.41\pm0.14~M_{\odot}$ and radius of $8.73\pm1.54~\rm km$ at 68% confidence) exists in 4U 1746-37. If another effect operated, 4U 1746-37 may contain an ultra low mass and small radius object ($M=0.21\pm0.06~M_{\odot},~R=6.26\pm0.99~\rm km$ at 68% confidence). Combined all possibilities, the mass of 4U 1746-37 is $0.41^{+0.70}_{-0.30}~M_\odot$ at 99.7% confidence. For such low mass NS, it could be reproduced by a self-bound compact star, i.e., quark star or quark-cluster star.Comment: accepted by Ap

A Genetic and Simulated Annealing Combined Algorithm for Optimization of Wideband Antenna Matching Networks

A genetic and simulated annealing combined algorithm is presented and applied to optimize broadband matching networks for antennas. As a result, advantages of both the genetic algorithm (GA) and simulated annealing (SA) are taken. Effectiveness and efficiency of the presented combined algorithm are demonstrated by optimization of a wideband matching network for a VHF/UHF discone-based antenna. The optimized parameters provide significant improvements of VSWR and transducer power gain for the antenna

Reading molecular messages from the intersections of high-order harmonic spectra at different orientations

We investigate the orientation dependence of high-order harmonic generation (HHG) from H$_2^+$ with different internuclear distances irradiated by intense laser fields both numerically and analytically. The calculated molecular HHG spectra are found to be sensitive to molecular axis orientation relative to incident laser field polarization and internuclear separation. In particular, the spectra calculated for different orientation angles demonstrate a kind of intersection, which is identified as arising due to intramolecular two-center interference in the HHG. The striking "intersection" phenomenon can be used to probe the molecular instantaneous structure.Comment: 5 pages,5 figure