Hand-held self-maneuvering unit Patent

Hand-held maneuvering unit for propulsion and attitude control of astronauts in zero or reduced gravity environmen

Probing of valley polarization in graphene via optical second-harmonic generation

Valley polarization in graphene breaks inversion symmetry and therefore leads to second-harmonic generation. We present a complete theory of this effect within a single-particle approximation. It is shown that this may be a sensitive tool to measure the valley polarization created, e.g., by polarized light and, thus, can be used for a development of ultrafast valleytronics in graphene.Comment: 5 pages, 3 figure

On the determination of anti-neutrino spectra from nuclear reactors

In this paper we study the effect of, well-known, higher order corrections to the allowed beta decay spectrum on the determination of anti-neutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even largely increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the anti-neutrino spectrum using synthetic beta spectra. It turns out, that a fit using only virtual beta branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for U235, Pu239 and Pu241 and confirm, within errors, recent results, which indicate a net 3% upward shift in energy averaged anti-neutrino fluxes. However, we also find significant shape differences which can in principle be tested by high statistics anti-neutrino data samples.Comment: 20 pages, 5 figures, 9 tables, added references, version accepted for publication in Phys. Rev. C. Corrected errors in tab. 1 and eqs. 18 and 19. Results and conclusion unchange

A HIERARCHICAL BAYES APPROACH TO MODELING CHOICE DATA: A STUDY OF WETLAND RESTORATION PROGRAMS

This study examines the factors the influence the values and importance that landowners place on the attributes of voluntary wetland restoration programs. Choice-based conjoint analysis, a stated preference method, was used to estimate the marginal utilities and values for restoration program attributes for North Carolina landowners. Landowner preferences were estimated at individual and aggregate levels to examine the importance of modeling heterogeneous preferences. Choice modeling performed at both aggregate and individual levels demonstrated the information gains from a disaggregated approach.Research Methods/ Statistical Methods,