46,672 research outputs found
Study of Permanent Magnet Focusing for Astronomical Camera Tubes
A design is developed of a permanent magnet assembly (PMA) useful as the magnetic focusing unit for the 35 and 70 mm (diagonal) format SEC tubes. Detailed PMA designs for both tubes are given, and all data on their magnetic configuration, size, weight, and structure of magnetic shields adequate to screen the camera tube from the earth's magnetic field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the magnetic field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application
Antidote application: an educational system for treatment of common toxin overdose
Poisonings account for almost 1% of emergency room visits each year. Time is a critical factor in dealing with a toxicologic emergency. Delay in dispensing the first antidote dose can lead to life-threatening sequelae. Current toxicological resources that support treatment decisions are broad in scope, time-consuming to read, or at times unavailable. Our review of current toxicological resources revealed a gap in their ability to provide expedient calculations and recommendations about appropriate course of treatment. To bridge the gap, we developed the Antidote Application (AA), a computational system that automatically provides patient-specific antidote treatment recommendations and individualized dose calculations. We implemented 27 algorithms that describe FDA (the US Food and Drug Administration) approved use and evidence-based practices found in primary literature for the treatment of common toxin exposure. The AA covers 29 antidotes recommended by Poison Control and toxicology experts, 19 poison classes and 31 poisons, which represent over 200 toxic entities. To the best of our knowledge, the AA is the first educational decision support system in toxicology that provides patient-specific treatment recommendations and drug dose calculations. The AA is publicly available at http://projects.met- hilab.org/antidote/
Is U3Ni3Sn4 best described as near a quantum critical point?
Although most known non-Fermi liquid (NFL) materials are structurally or
chemically disordered, the role of this disorder remains unclear. In
particular, very few systems have been discovered that may be stoichiometric
and well ordered. To test whether U3Ni3Sn4 belongs in this latter class, we
present measurements of the x-ray absorption fine structure (XAFS) of
polycrystalline and single-crystal U3Ni3Sn4 samples that are consistent with no
measurable local structural disorder. We also present temperature-dependent
specific heat data in applied magnetic fields as high as 8 T that show features
that are inconsistent with the antiferromagnetic Griffiths' phase model, but do
support the conclusion that a Fermi liquid/NFL crossover temperature increases
with applied field. These results are inconsistent with theoretical
explanations that require strong disorder effects, but do support the view that
U3Ni3Sn4 is a stoichiometric, ordered material that exhibits NFL behavior, and
is best described as being near an antiferromagnetic quantum critical point.Comment: 9 pages, 8 figures, in press with PR
Research program to develop a technology improvement program for closed die forging Final report
Upset forging tests on aluminum and titanium alloys and maraging steel using high temperature die
Numerical solution of the Navier-Stokes equations for arbitrary two-dimensional multi-element airfoils
The development of a numerical simulation of time dependent, turbulent, compressible flow about two dimensional multi-element airfoils of arbitrary shape is described. The basis of this simulation is a technique of automatic numerical generation of coordinate systems fitted to the multiple bodies regardless of their number or shape. Procedures developed whereby the coordinate lines are automatically concentrated in the boundary layer at any Reynolds number are discussed. The compressible turbulent solution involves an algebraic eddy viscosity turbulence model. The laminar version was run for transonic flow at free stream Mach numbers up to 0.9
SU(3)_LxU(1)_N Model for Right-Handed Neutrino Neutral Currents
A model based on the \mbox{SU(3)}_L\otimes \mbox{U(1)}_N gauge group, in
which neutrinos have right-handed neutral currents is considered. We argue that
in order to have a result consistent with low-energy one, the right-handed
neutrino component must be treated as correction instead of an equivalent spin
state.Comment: 6 pages, Latex, no figures, Accepted for publication in Phys. Rev.
Dynamic magnetic response of infinite arrays of ferromagnetic particles
Recently developed techniques to find the eigenmodes of a ferromagnetic
particle of arbitrary shape, as well as the absorption in the presence of an
inhomogeneous radio-frequency field, are extended to treat infinite lattices of
such particles. The method is applied to analyze the results of recent FMR
experiments, and yields substantially good agreement between theory and
experiment
Evolution of Nuclear Shell Structure due to the Pion Exchange Potential
The evolution of nuclear shell structure is investigated for the first time
within density-dependent relativistic Hartree-Fock theory and the role of
-exchange potential is studied in detail. The energy differences between
the neutron orbits \Lrb{\nu1h_{9/2},\nu 1i_{13/2}} in the N=82 isotones and
between the proton ones \Lrb{\pi1g_{7/2},\pi1h_{11/2}} in the Z=50 isotopes
are extracted as a function of neutron excess . A kink around for
the N=82 isotones is found as an effect resulting from pion correlations. It is
shown that the inclusion of -coupling plays a central role to provide
realistic isospin dependence of the energy differences. In particular, the
tensor part of the -coupling has an important effect on the characteristic
isospin dependence observed in recent experiments.Comment: 4 pages and 4 figure
Efficacy of alternative seating on attention, in-seat behavior, and occupational performance in children with Attention Deficit Hyperactivity Disorder
Currently, there is one systematic review conducted by Gochenour and Poskey7 that synthesize current research evidence regarding alternative seating for students with attention difficulties. A limitation of this review, as noted by the authors, is a lack of a consistent definition of attention difficulty in the studies they included. A systematic review focused on a specific, well-defined diagnosis will better contribute to practice recommendations since these recommendations will be tailored to a clear and comprehensive understanding of the child’s attentional and occupational challenges. The review also included studies of children with autism spectrum disorder (ASD).7 While those with ASD may also have difficulties with attention, in-seat behavior and occupational performance, the underlying mechanism yielding these symptoms may be different than in children with ADHD. Thus, alternative seating may not work in the same way for children with ASD as it would for children with ADHD.7 Thus, a systematic review is needed to examine the evidence from all current studies regarding alternative seating on improving attention, in-seat behavior and occupational performance in students with ADHD to increase evidence-based practice in the field of occupational therapy
AN INTRASEASONAL BIOECONOMIC MODEL OF PLRV NET NECROSIS
A bioeconomic model is developed as an IPM planning tool to combat PLRV net necrosis in the PNW potato industry. Environmental/biological and production processes are linked to marketing activities using discrete time control. We find that pesticides can be optimally timed to reduce applications and still protect against net necrosis.Crop Production/Industries, Environmental Economics and Policy,
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