20,913 research outputs found
Development of advanced digital techniques for data acquisition processing and communication Interim scientific report
Image correlation and computerized simulation applied to data acquisition and imaging technique
The steady state in noncollinear magnetic multilayers
There are at least two different putative steady state solutions for current
across noncollinear magnetic multilayers; one has a discontinuity in the spin
current at the interface the other is continuous. We compare the resistance of
the two and find the solution with the continuous spin currents is lower. By
using the entropic principle we can state that this solution is a better
estimate of the resistance for a noncollinear magneticComment: 14 pages, 4 figures,Submitted to Physical Review
Electromagnetic radiation screening of microcircuits for long life applications
The utility of X-rays as a stimulus for screening high reliability semiconductor microcircuits was studied. The theory of the interaction of X-rays with semiconductor materials and devices was considered. Experimental measurements of photovoltages, photocurrents, and effects on specified parameters were made on discrete devices and on microcircuits. The test specimens included discrete devices with certain types of identified flaws and symptoms of flaws, and microcircuits exhibiting deviant electrical behavior. With a necessarily limited sample of test specimens, no useful correlation could be found between the X-ray-induced electrical response and the known or suspected presence of flaws
Different steady states for spin currents in noncollinear multilayers
We find there are at least two different steady states for transport across
noncollinear magnetic multilayers. In the conventional one there is a
discontinuity in the spin current across the interfaces which has been
identified as the source of current induced magnetic reversal; in the one
advocated herein the spin torque arises from the spin accumulation transverse
to the magnetization of a magnetic layer. These two states have quite different
attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics:
Condensed Matte
Analytical modeling of circuit aerodynamics in the new NASA Lewis wind tunnel
Rehabilitation and extention of the capability of the altitude wind tunnel (AWT) was analyzed. The analytical modeling program involves the use of advanced axisymmetric and three dimensional viscous analyses to compute the flow through the various AWT components. Results for the analytical modeling of the high speed leg aerodynamics are presented; these include: an evaluation of the flow quality at the entrance to the test section, an investigation of the effects of test section bleed for different model blockages, and an examination of three dimensional effects in the diffuser due to reentry flow and due to the change in cross sectional shape of the exhaust scoop
Confinement Effects on the Kinetics and Thermodynamics of Protein Dimerization
In the cell, protein complexes form relying on specific interactions between
their monomers. Excluded volume effects due to molecular crowding would lead to
correlations between molecules even without specific interactions. What is the
interplay of these effects in the crowded cellular environment? We study
dimerization of a model homodimer both when the mondimers are free or tethered
to each other. We consider a structured environment: Two monomers first diffuse
into a cavity of size and then fold and bind within the cavity. The folding
and binding are simulated using molecular dynamics based on a simplified
topology based model. The {\it confinement} in the cell is described by an
effective molecular concentration . A two-state coupled folding
and binding behavior is found. We show the maximal rate of dimerization
occurred at an effective molecular concentration M which is a
relevant cellular concentration. In contrast, for tethered chains the rate
keeps at a plateau when .
For both the free and tethered cases, the simulated variation of the rate of
dimerization and thermodynamic stability with effective molecular concentration
agrees well with experimental observations. In addition, a theoretical argument
for the effects of confinement on dimerization is also made
Perceived Masculinity/Femininity of Managers and the Feedback Environment
Past research suggests that the masculinity/femininity of a supervisor plays a role in the effectiveness of his/her leadership in organizations. This study looked into the relationship between the perceived masculinity and femininity of supervisors by employees and the feedback environment. The data for the research were collected from 66 men and 78 women in the United States who were working 20 or more hours per week using Amazon’s Mechanical Turk website. The survey was the combination of the supervisor subscale of the Feedback Environment Scale (FES) and a slightly modified version of the Personal Attributes Questionnaire (PAQ). Each of the seven dimensions of the Feedback Environment Scale were correlated with the ratings on the Personal Attributes Questionnaire. The results identified a relationship between the perceived masculinity and femininity of supervisors and the feedback environment. It was also discovered that femininity significantly correlated more with the feedback environment than masculinity
Probabilistic Cross-Identification of Astronomical Sources
We present a general probabilistic formalism for cross-identifying
astronomical point sources in multiple observations. Our Bayesian approach,
symmetric in all observations, is the foundation of a unified framework for
object matching, where not only spatial information, but physical properties,
such as colors, redshift and luminosity, can also be considered in a natural
way. We provide a practical recipe to implement an efficient recursive
algorithm to evaluate the Bayes factor over a set of catalogs with known
circular errors in positions. This new methodology is crucial for studies
leveraging the synergy of today's multi-wavelength observations and to enter
the time-domain science of the upcoming survey telescopes.Comment: Accepted for publication in the Astrophysical Journal, 8 pages, 1
figure, emulateapj w/ apjfont
Flood fatalities in eastern Kentucky and the public health legacy of mountaintop removal coal mining
Heavy rains at night caused severe flooding in eastern Kentucky on 28 July 2022, resulting in 39 deaths. Using publicly available information, we assembled a database of these fatalities, including demographic characteristics and location of death. We perturbed fatality locations and plotted them on a topographical map highlighting mountaintop removal mining with valley fill sites, where mountaintops were excavated to mine thin seams of coal. This map reveals many flood fatalities occurred along rivers or streams near such sites. Previous research suggests that surface mining has contributed to the majority of land cover change in this region, and this has increased storm water runoff. The legacy of coal mining in Central Appalachia could thus present immediate challenges to public health and safety beyond more frequently studied health outcomes associated with occupational and environmental exposures. A review of prior surface mining legislation to assess its effectiveness is warranted
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