Low-frequency vibration environment for five Shuttle missions

The Microgravity Science and Applications Division's (MSAD) program to record and analyze the Shuttle's vibration environment is reviewed. This program provides microgravity science investigators with time and frequency analyses of the acceleration environment during their experiments' operation. Information is also provided for future investigators on the expected Shuttle vibration environment. As background, the two major elements of the program are discussed, the Space Acceleration Measurement System (SAMS) and the Acceleration Characterization and Analysis Project (ACAP). A comparison of the acceleration measurements from five Shuttle missions is discussed

Convergence of many-body wavefunction expansions using a plane wave basis: from the homogeneous electron gas to the solid state

Using the finite simulation-cell homogeneous electron gas (HEG) as a model, we investigate the convergence of the correlation energy to the complete basis set (CBS) limit in methods utilising plane-wave wavefunction expansions. Simple analytic and numerical results from second-order M{\o}ller-Plesset theory (MP2) suggest a 1/M decay of the basis-set incompleteness error where M is the number of plane waves used in the calculation, allowing for straightforward extrapolation to the CBS limit. As we shall show, the choice of basis set truncation when constructing many-electron wavefunctions is far from obvious, and here we propose several alternatives based on the momentum transfer vector, which greatly improve the rate of convergence. This is demonstrated for a variety of wavefunction methods, from MP2 to coupled-cluster doubles theory (CCD) and the random-phase approximation plus second-order screened exchange (RPA+SOSEX). Finite basis-set energies are presented for these methods and compared with exact benchmarks. A transformation can map the orbitals of a general solid state system onto the HEG plane wave basis and thereby allow application of these methods to more realistic physical problems.Comment: 15 pages, 9 figure

Design and qualification of the SEU/TD Radiation Monitor chip

This report describes the design, fabrication, and testing of the Single-Event Upset/Total Dose (SEU/TD) Radiation Monitor chip. The Radiation Monitor is scheduled to fly on the Mid-Course Space Experiment Satellite (MSX). The Radiation Monitor chip consists of a custom-designed 4-bit SRAM for heavy ion detection and three MOSFET's for monitoring total dose. In addition the Radiation Monitor chip was tested along with three diagnostic chips: the processor monitor and the reliability and fault chips. These chips revealed the quality of the CMOS fabrication process. The SEU/TD Radiation Monitor chip had an initial functional yield of 94.6 percent. Forty-three (43) SEU SRAM's and 14 Total Dose MOSFET's passed the hermeticity and final electrical tests and were delivered to LL

Quantum theory of electric polarization nonlinearity in metal nanofilms

We develop a quantum theory of electron confinement in metal nanofilms. The theory is used to compute the nonlinear response of the film to a static or low-frequency external electric field and to investigate the role of boundary conditions imposed on the metal surface. We find that the sign and magnitude of the nonlinear polarizability depends dramatically on the type of boundary condition used.Comment: Accepted to PRB in this for

Accuracy of 3-Dimensional Transoesophageal Echocardiography in Assessment of Prosthetic Mitral Valve Dehiscence with Comparison to Anatomical Specimens

The evolution of echocardiography from 2-Dimensional Transthoracic Echo through to real time 3-Dimensional Transoesophageal Echo has enabled more accurate visualisation and quantification of valvular disorders especially prosthetic mitral valve paravalvular regurgitation. However, validation of accuracy is rarely confirmed by surgical or post-mortem specimens. We present a case directly comparing different echocardiographic modality images to post mortem specimens in a patient with prosthetic mitral valve paravalvular regurgitation

Ariel - Volume 8 Number 5

Executive Editor James W. Lockard. Jr. Business Manager Neeraj K. Kanwal University News Martin Trichtinger World News Doug Hiller Opinions Elizabeth A. McGuire Features Patrick P. Sokas Sports Desk Shahab S. Minassian Managing Editor Edward H. Jasper Managing Associate Brenda Peterson Photography Editor Robert D. Lehman, Jr. Graphics Christine M. Kuhnl

A study of concept options for the evolution of Space Station Freedom

Two conceptual evolution configurations for Space Station Freedom, a research and development configuration, and a transportation node configuration are described and analyzed. Results of pertinent analyses of mass properties, attitude control, microgravity, orbit lifetime, and reboost requirements are provided along with a description of these analyses. Also provided are brief descriptions of the elements and systems that comprise these conceptual configurations

WMAP data and the curvature of space

Inter alia, the high precision WMAP data on Cosmic Microwave Background Radiation marginally indicate that the universe has positively curved (and hence spherical) spatial sections. In this paper, we take this data seriously and consider some of the consequences for the background dynamics. In particular, we show that this implies a limit to the number of e-foldings that could have taken place in the inflationary epoch; however this limit is consistent with some inflationary models that solve all the usual cosmological problems and are consistent with standard structure formation theory.Comment: 4 pages, 2 figure

Evaluating High-Dose Rivastigmine Patch in Severe Alzheimer’s Disease: Analyses with Concomitant Memantine Usage as a Factor

Background: ACTION, a 24-week, prospective, randomized, parallel-group, double-blind study in patients with severe Alzheimer’s disease (AD), demonstrated significant efficacy of 13.3 mg/24 h versus 4.6 mg/24 h rivastigmine patch on the Severe Impairment Battery (SIB) and Alzheimer’s Disease Cooperative Study–Activities of Daily Living scale–Severe Impairment Version (ADCS-ADL-SIV). Overall, 61% of the study population received at least 1 dose of concomitant memantine, regardless of dose or duration. This retrospective analysis investigated the effects of concomitant memantine on the efficacy, safety and tolerability of 13.3 mg/24 h versus 4.6 mg/24 h rivastigmine patch. Methods: Patients were stratified according to whether or not they received at least one dose of concomitant memantine during the double-blind phase. Changes from baseline on the SIB and ADCS-ADL-SIV were compared using analysis of covariance (ANCOVA) with treatment, pooled center, memantine usage and treatment-by-memantine as factors, and baseline as a covariate. Safety and tolerability were assessed. Results: Memantine-treated patients were younger than those not receiving memantine (mean 75.9 and 78.8 years, respectively), with a lower screening Mini-Mental State Examination (8.6 and 9.2, respectively). ANCOVA confirmed there was no significant interaction (p>0.1) between study treatment and memantine use on the SIB or ADCS-ADL-SIV. The incidence of adverse events was: 71.4%, 13.3 mg/24 h patch with memantine; 79.7%, 13.3 mg/24 h patch alone; 74.7%, 4.6 mg/24 h patch with memantine; and 71.1%, 4.6 mg/24 h patch alone. Conclusion: These data suggest benefit of 13.3 mg/24 h versus 4.6 mg/24 h rivastigmine patch, regardless of concomitant memantine use. The incidence of adverse events with highdose patch was similar in memantine-treated patients and those not receiving memantine

Method for characterizing the upset response of CMOS circuits using alpha-particle sensitive test circuits

A method for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. A technique utilizing test structures to quickly and inexpensively characterize the SEU sensitivity of standard cell latches intended for use in a space environment. This bench-level approach utilizes alpha particles to induce upsets in a low LET sensitive 4-k bit test SRAM. This SRAM consists of cells that employ an offset voltage to adjust their upset sensitivity and an enlarged sensitive drain junction to enhance the cell's upset rate