Finite difference time domain implementation of surface impedance boundary conditions

Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media throughout the solution volume. The standard approach is to approximate the surface impedance over a very small bandwidth by its value at the center frequency, and then use that result in the boundary condition. Two implementations of the surface impedance boundary condition are presented. One implementation is a constant surface impedance boundary condition and the other is a dispersive surface impedance boundary condition that is applicable over a very large frequency bandwidth and over a large range of conductivities. Frequency domain results are presented in one dimension for two conductivity values and are compared with exact results. Scattering width results from an infinite square cylinder are presented as a 2-D demonstration. Extensions to 3-D should be straightforward

Wideband finite difference time domain implementation of surface impedance boundary conditions for good conductors

Surface impedance boundary conditions are used to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be used to avoid using small cells, made necessary by shorter wavelengths in conducting media, throughout the solution volume. A one dimensional implementation is presented for a surface impedance boundary condition for good conductors in the Finite Difference Time Domain (FDTD) technique. In order to illustrate the FDTD surface impedance boundary condition, a planar air-lossy dielectric interface is considered

The LeFE Algorithm: Embracing the Complexity of Gene Expression in the Interpretation of Microarray Data

The LeFE algorithm has been developed to address the complex, non-linear regulation of gene expression. Interpretation of microarray data remains a challenge, and most methods fail to consider the complex, nonlinear regulation of gene expression. To address that limitation, we introduce Learner of Functional Enrichment (LeFE), a statistical/machine learning algorithm based on Random Forest, and demonstrate it on several diverse datasets: smoker/never smoker, breast cancer classification, and cancer drug sensitivity. We also compare it with previously published algorithms, including Gene Set Enrichment Analysis. LeFE regularly identifies statistically significant functional themes consistent with known biology.National Cancer Institute's Center for Cancer Researc

Recent Decisions

Comments on recent decisions by Lawrence A. Kane, Jr., Vernon O. Teofan, Thomas S. Calder, John Rogers, James Carroll Booth, Paul M. Kraus, Jack Economou, and Robert P. Gorman

Wideband finite difference time domain implementation of surface impedance boundary conditions for good conductors

Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media, throughout the solution volume. A 1-D implementation for a surface impedance boundary condition for good conductors in the Finite Difference Time Domain (FDTD) technique

Cosmic ray antimatter from supersymmetric dark matter

In this paper we study the antiproton, positron and gamma-ray fluxes resulting from the annihilation of supersymmetric dark matter in our galactic halo. We show that the requirement of closure imposed by inflationary cosmologies constrains the supersymmetric dark matter to be either a relatively pure photino eigenstate or a relatively pure higgsino eigenstate, or possibly a scalar neutrino with a mass less than 4 GeV. The photino choice can lead to observable fluxes when sfermion masses are [lsim] 50-60 GeV. Such a scenario is testable via the radiative production of photinos at PEP and PETRA. The higgsino scenario leads to observable fluxes independent of sfermion masses, provided H01|0>/H02|0> = v1/v2 [gsim] 2. In constrast, sneutrino dark matter annihilates almost entirely into neutrinos, resulting in a monochromatic neutrino flux that is probably unobservable.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26293/1/0000378.pd

Identifying Effective Classroom Practices Using Student Achievement Data

Recent research has confirmed both the importance of teachers in producing student achievement growth and in the variability across teachers in the ability to do that. Such findings raise the stakes on our ability to identify effective teachers and teaching practices. This paper combines information from classroom-based observations and measures of teachers’ ability to improve student achievement as a step toward addressing these challenges. We find that classroom based measures of teaching effectiveness are related in substantial ways to student achievement growth. Our results point to the promise of teacher evaluation systems that would use information from both classroom observations and student test scores to identify effective teachers. Our results also offer information on the types of practices that are most effective at raising achievement.

Youth Single-Sport Specialization in Professional Baseball Players.

Background: An increasing number of youth baseball athletes are specializing in playing baseball at younger ages. Purpose: The purpose of our study was to describe the age and prevalence of single-sport specialization in a cohort of current professional baseball athletes. In addition, we sought to understand the trends surrounding single-sport specialization in professional baseball players raised within and outside the United States (US). Study Design: Cross-sectional study; Level of evidence, 3. Methods: A survey was distributed to male professional baseball athletes via individual team athletic trainers. Athletes were asked if and at what age they had chosen to specialize in playing baseball at the exclusion of other sports, and data were then collected pertaining to this decision. We analyzed the rate and age of specialization, the reasons for specialization, and the athlete\u27s perception of injuries related to specialization. Results: A total of 1673 professional baseball athletes completed the survey, representing 26 of the 30 Major League Baseball (MLB) organizations. Less than half (44.5%) of professional athletes specialized in playing a single sport during their childhood/adolescence. Those who reported specializing in their youth did so at a mean age of 14.09 ± 2.79 years. MLB players who grew up outside the US specialized at a significantly earlier age than MLB players native to the US (12.30 ± 3.07 vs 14.89 ± 2.24 years, respectively; Conclusion: This study challenges the current trends toward early youth sport specialization, finding that the majority of professional baseball athletes studied did not specialize as youth and that those who did specialize did so at a mean age of 14 years. With the potential cumulative effects of pitching and overhead throwing on an athlete\u27s arm, the trend identified in this study toward earlier specialization within baseball is concerning