Theory of imaging a photonic crystal with transmission near-field optical microscopy

While near-field scanning optical microscopy (NSOM) can provide optical images with resolution much better than the diffraction limit, analysis and interpretation of these images is often difficult. We present a theory of imaging with transmission NSOM that includes the effects of tip field, tip/sample coupling, light propagation through the sample and light collection. We apply this theory to analyze experimental NSOM images of a nanochannel glass (NCG) array obtained in transmission mode. The NCG is a triangular array of dielectric rods in a dielectric glass matrix with a two-dimensional photonic band structure. We determine the modes for the NCG photonic crystal and simulate the observed data. The calculations show large contrast at low numerical aperture (NA) of the collection optics and detailed structure at high NA consistent with the observed images. We present calculations as a function of NA to identify how the NCG photonic modes contribute to and determine the spatial structure in these images. Calculations are presented as a function of tip/sample position, sample index contrast and geometry, and aperture size to identify the factors that determine image formation with transmission NSOM in this experiment.Comment: 28 pages of ReVTex, 14 ps figures, submitted to Phys. Rev.

Temperature dependence of binary and ternary recombination of H3+ ions with electron

We study binary and the recently discovered process of ternary He-assisted recombination of H3+ ions with electrons in a low temperature afterglow plasma. The experiments are carried out over a broad range of pressures and temperatures of an afterglow plasma in a helium buffer gas. Binary and He-assisted ternary recombination are observed and the corresponding recombination rate coefficients are extracted for temperatures from 77 K to 330 K. We describe the observed ternary recombination as a two-step mechanism: First, a rotationally-excited long-lived neutral molecule H3* is formed in electron-H3+ collisions. Second, the H3* molecule collides with a helium atom that leads to the formation of a very long-lived Rydberg state with high orbital momentum. We present calculations of the lifetimes of H3* and of the ternary recombination rate coefficients for para and ortho-H3+. The calculations show a large difference between the ternary recombination rate coefficients of ortho- and para-H3+ at temperatures below 300 K. The measured binary and ternary rate coefficients are in reasonable agreement with the calculated values.Comment: 15 page

Effects of Carbon Dioxide on Glucose Incorporation in Flatworms

Paper by James S. McDaniel, Austin J. MacInnis, and Clark P. Rea

Formation of plasma around a small meteoroid: 1. Kinetic theory

This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF

Weight Management Program for Fire Fighters: Feasibility Pilot

Please view abstract in the attached PDF fil

Secure Distributed Virtual Conferencing: Multicast or Bust

We describe a secure distributed virtual conferencing application (SDVC) that provides high quality streaming video and audio using IP multicast for efficient distribution, using strong authentication via cryptographic means and optionally providing fully encrypted communication without sacrificing quality of the medium or the user experience. We summarize our experiences with SDVC in a recent live demonstration and conclude with a discussion of future plans.http://deepblue.lib.umich.edu/bitstream/2027.42/107912/1/citi-tr-99-1.pd

ENGINEERING AN OLEOGINOUS YEAST FOR THE PRODUCTION OF BIODIESEL

poster abstractThere are economic and social interests in replacing the current energy dependence we have on petroleum-based oleochemicals. Yarrowia lipolytica, an oleaginous yeast, has the ability to metabolize unique carbon sources, particularly hydrocarbons and to accumulate large amounts of lipids which could be developed into a source of biodiesel. The ability of Y. lipolytica to accumulate triacylglycerols in lipid droplets and the complete sequencing of its genome make Y. lipolytica a viable organism to genetically engineer for the production of large quantities of biodiesel precursors. The purpose of this project is to genetically modify Y. lipolytica to further increase its production of triacylglycerols by knocking out genes that encode enzymes involved in the β-oxidation of fatty acids. This genetic modification will be accomplished by using homologous recombination to disrupt the genes POX3-5 and POT1. The 5’ and 3’ untranslated regions of POX3-5 and POT1 were amplified by polymerase chain reaction and cloned to allow a drug resistance gene to be introduced between them. Following cloning, these genes will be knocked out from the Y. lipolytica genome using drug resistance as a marker. The disruption of these genes is expected to increase the accumulation of triacylglycerols in Y. lipolytica lipid droplets versus the wild-type. Progress towards the goals of this project will be reported

Free-field propagation of high intensity noise

Research on high intensity (finite amplitude) acoustic waves shows that nonlinear distortion effects generally result in a shift of energy to higher frequencies. The higher intensities associated with supersonic jets would therefore indicate that high frequency enhancement of the spectrum should occur, resulting in the differences observed between subsonic and supersonic jets. A 10,000 acoustic watt source installed in an anechoic chamber generates sound levels such that acoustic shocks are readily observable. Dual frequency excitation of the source produces a strong parametric effect with a difference frequency comparable in level to the primary frequency. The test set up and recording equipment being used to determine the finite amplitude noise representative of an actual supersonic jet are described as well as the development of a computer program based on Burger's equation. The spectra of 1/2 octave band, 1 kHz sine wave, and dual frequency input and output are presented in graphs along with waveforms at Z = .025, 0.1, and 1.0

Shear modulus of the hadron-quark mixed phase

Robust arguments predict that a hadron-quark mixed phase may exist in the cores of some "neutron" stars. Such a phase forms a crystalline lattice with a shear modulus higher than that of the crust due to the high density and charge separation, even allowing for the effects of charge screening. This may lead to strong continuous gravitational-wave emission from rapidly rotating neutron stars and gravitational-wave bursts associated with magnetar flares and pulsar glitches. We present the first detailed calculation of the shear modulus of the mixed phase. We describe the quark phase using the bag model plus first-order quantum chromodynamics corrections and the hadronic phase using relativistic mean-field models with parameters allowed by the most massive pulsar. Most of the calculation involves treating the "pasta phases" of the lattice via dimensional continuation, and we give a general method for computing dimensionally continued lattice sums including the Debye model of charge screening. We compute all the shear components of the elastic modulus tensor and angle average them to obtain the effective (scalar) shear modulus for the case where the mixed phase is a polycrystal. We include the contributions from changing the cell size, which are necessary for the stability of the lower-dimensional portions of the lattice. Stability also requires a minimum surface tension, generally tens of MeV/fm^2 depending on the equation of state. We find that the shear modulus can be a few times 10^33 erg/cm^3, two orders of magnitude higher than the first estimate, over a significant fraction of the maximum mass stable star for certain parameter choices.Comment: 22 pages, 12 figures, version accepted by Phys. Rev. D, with the corrections to the shear modulus computation and Table I given in the erratu