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Green, Michael

Publications and source records attributed to Green, Michael.

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Close to Home: Employment Outcomes for Recent Radiation Oncology Graduates

Purpose: To characterize the practice type and location of radiation oncology (RO) residents graduating in 2013. Methods and Materials: Graduates completing RO residency in 2013 were identified, and for each, postgraduate practice setting (academic vs private practice) and location were identified. Characteristics of the graduates, including details regarding their institutions of medical school and residency education, were collected and analyzed. Results: Data were obtained from 146 of the 154 RO graduates from the class of 2013. Employment data were available for 142 graduates. Approximately one-third of graduates were employed in the same state as residency (36.6%), approximately two-thirds (62.0%) in the same region as residency, and nearly three-fourths (73.9%) in the same region as medical school or residency completion. Of the 66 graduates (46.5%) working in academics, 40.9% were at the same institution where they completed residency. Most trainees (82.4%) attended medical schools with RO residency programs. Conclusions: Although personal factors may attract students to train in a particular area, the location of medical school and residency experiences may influence RO graduate practice location choice. Trends in the geographic distribution of graduating radiation oncologists can help identify and better understand disparities in access to RO care. Steps to improve access to RO care may include interventions at the medical student or resident level, such as targeting students at medical schools without associated residency programs and greater resident exposure to underserved areas.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Caution Is Required in Interpretation of Mutations in the Voltage Sensing Domain of Voltage Gated Channels as Evidence for Gating Mechanisms

The gating mechanism of voltage sensitive ion channels is generally considered to be the motion of the S4 transmembrane segment of the voltage sensing domains (VSD). The primary supporting evidence came from R→C mutations on the S4 transmembrane segment of the VSD, followed by reaction with a methanethiosulfonate (MTS) reagent. The cys side chain is –SH (reactive form –S−); the arginine side chain is much larger, leaving space big enough to accommodate the MTS sulfonate head group. The cavity created by the mutation has space for up to seven more water molecules than were present in wild type, which could be displaced irreversibly by the MTS reagent. Our quantum calculations show there is major reorientation of three aromatic residues that face into the cavity in response to proton displacement within the VSD. Two phenylalanines reorient sufficiently to shield/unshield the cysteine from the intracellular and extracellular ends, depending on the proton positions, and a tyrosine forms a hydrogen bond to the cysteine sulfur with its side chain –OH. These could produce the results of the experiments that have been interpreted as evidence for physical motion of the S4 segment, without physical motion of the S4 backbone. The computations strongly suggest that the interpretation of cysteine substitution reaction experiments be re-examined in the light of these considerations.

Biochemistry & Molecular Biology↗
NASA NTRS1989

Theoretical and experimental investigation of the aeroelastic stability of an advanced bearingless rotor in hover and forward flight

The aeroelastic stability of a shaft-fixed, 1/8th Froude scaled bearingless rotor was investigated in a series of wind tunnel experiments simulating a wide range of operating conditions. A finite element formulation was used to perform a parallel theoretical analysis, with the goal of determining whether a bearingless rotor system could be made aeroelastically stable without the incorporation of auxilliary dampers. A quick estimate of lag mode damping was provided by a refined moving-block analysis implemented in real time which predicted similar damping values. Model rotor and blade properties were also determined, and these properties were used as inputs for a newly refined bearingless rotor analysis. Predicted results were compared with experimental results in hover and forward flight. Results indicated that soft pitch link stiffness increases pitch-lag coupling and stabilizes lag mode stability in hover and at low advance ratios, but destabilizes at higher advance ratios.

Wang, James M.↗