74,562 research outputs found
Low-temperature acoustic characteristics of the amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5
The temperature dependences of the sound velocity v and attenuation alpha of high-frequency (50–160 MHz) sound in the bulk amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 are studied at helium temperatures in the normal and superconducting states. The alloy is characterized by a relatively small constant C determining the intensity of interaction between an elastic wave and two-level systems. The density of states of the latter systems is estimated. The peculiarities in the variation of v during the superconducting transition point to the possibility of a gapless superconductivity in a narrow temperature interval near Tc
Increasing Autism Awareness in Inner-City Churches: A Brief Report
Autism diagnosis rates trail significantly in the African American community. This pre-test post-test pilot study evaluated an African American inner-city church health ambassadors (HAs) autism spectrum disorder (ASD) awareness training session. The participants included 12 HAs who attended the 1 hour training session organized by the National Baptist Convention, USA, Inc. Results of surveys showed higher mean scores post training for (1) HA attitudes about the potential for children to improve with applied behavior analysis therapy; (2) HA self-efficacy for having information about ASD screening materials; (3) strategies HAs could use to help parents/caregivers of children with developmental delays and challenging behaviors; (4) HA confidence in referrals for children with signs of ASD; (5) HA knowledge of measures to take to maximize a child\u27s chance of receiving an ASD evaluation; and (6) HA comfort for talking to parents about children with challenging behaviors. Several of these effects were maintained 3 months later. Findings underscore the usefulness of the intervention for increasing the dissemination of knowledge about ASD and the opportunity to positively affect ASD screening, early intervention, and policy standards applicable to this vulnerable population
Computer code to interchange CDS and wave-drag geometry formats
A computer program has been developed on the PRIME minicomputer to provide an interface for the passage of aircraft configuration geometry data between the Rockwell Configuration Development System (CDS) and a wireframe geometry format used by aerodynamic design and analysis codes. The interface program allows aircraft geometry which has been developed in CDS to be directly converted to the wireframe geometry format for analysis. Geometry which has been modified in the analysis codes can be transformed back to a CDS geometry file and examined for physical viability. Previously created wireframe geometry files may also be converted into CDS geometry files. The program provides a useful link between a geometry creation and manipulation code and analysis codes by providing rapid and accurate geometry conversion
Gas phase hydrogen permeation in alpha titanium and carbon steels
Commercially pure titanium and heats of Armco ingot iron and steels containing from 0.008-1.23 w/oC were annealed or normalized and machined into hollow cylinders. Coefficients of diffusion for alpha-Ti and alpha-Fe were determined by the lag-time technique. Steady state permeation experiments yield first power pressure dependence for alpha-Ti and Sievert's law square root dependence for Armco iron and carbon steels. As in the case of diffusion, permeation data confirm that alpha-titanium is subject to at least partial phase boundary reaction control while the steels are purely diffusion controlled. The permeation rate in steels also decreases as the carbon content increases. As a consequence of Sievert's law, the computed hydrogen solubility decreases as the carbon content increases. This decreases in explained in terms of hydrogen trapping at carbide interfaces. Oxidizing and nitriding the surfaces of alpha-titanium membranes result in a decrease in the permeation rate for such treatment on the gas inlet surfaces but resulted in a slight increase in the rate for such treatment on the gas outlet surfaces. This is explained in terms of a discontinuous TiH2 layer
Evaluation of remote sensing in control of pink bollworm in cotton
The author has identified the following significant results. This project is to identify and map cotton fields in the southern deserts of California. Cotton in the Imperial, Coachella, and Palo Verde Valleys is heavily infested by the pink bollworm which affects both the quantity and quality of cotton produced. In California the growing season of cotton is regulated by establishing planting and plowdown dates. These procedures ensure that the larvae, whose diapause or resting period occurs during the winter months, will have no plant material on which to feed, thus inhibiting spring moth emergence. the underflight data from the U-2 aircraft has shound that it is possible to detect the differences between a growing, a defoliated, and plowed down field providing the locations of the fields are known. The ERTS-1 MSS data are being analyzed using an I2S optical color combiner to determine which combinations of dates and colors will identify cotton fields and thus provide the data needed to produce maps of the fields for the forthcoming season
Evaluation of remote sensing in control of pink bollworm in cotton
The author has identified the following significant results. This investigation is to evaluate the use of a satellite in monitoring the cotton production regulation program of the State of California as an aid in controlling pink bollworm infestation in the southern deserts of California. Color combined images of ERTS-1 multispectral images simulating color infrared are being used for crop identification. The status of each field (crop, bare, harvested, wet, plowed) is mapped from the imagery and is then compared to ground survey information taken at the time of ERTS-1 overflights. A computer analysis has been performed to compare field and satellite data to a crop calendar. Correlation to date has been 97% for field condition. Actual crop identification varies; cotton identification is only 63% due to lack of full season coverage
Model for Dissipative Highly Nonlinear Waves in Dry Granular Systems
A model is presented for the characterization of dissipative effects on
highly nonlinear waves in one-dimensional dry granular media. The model
includes three terms: Hertzian, viscoelastic, and a term proportional to the
square of the relative velocity of particles. The model outcomes are confronted
with different experiments where the granular system is subject to several
constraints for different materials. Excellent qualitative and quantitative
agreement between theory and experiments is found.Comment: Link to the Journal: http://prl.aps.org/abstract/PRL/v104/i11/e11800
Effects of confinement on the permanent electric-dipole moment of Xe atoms in liquid Xe
Searches for permanent electric-dipole moments (EDM) of atoms provide
important constraints on competing extensions to the standard model of
elementary particles. Recently proposed experiment with liquid Xe [M.V.
Romalis and M.P. Ledbetter, Phys. Rev. Lett. \textbf{87}, 067601 (2001)] may
significantly improve present limits on the EDMs. To interpret experimental
data in terms of CP-violating sources, one must relate measured atomic EDM to
various model interactions via electronic-structure calculations. Here we study
density dependence of atomic EDMs. The analysis is carried out in the framework
of the cell model of the liquid coupled with relativistic atomic-structure
calculations. We find that compared to an isolated atom, the EDM of an atom of
liquid Xe is suppressed by about 40%
Sound attenuation in the superconducting amorphous alloy ZrTiCuNiBe
The superconducting energy gap and the parameter of the intensity of electron
scattering at two-level systems in amorphous ZrTiCuNiBe are determined from the
results of measurements of sound attenuation. The mechanism of adiabatic
renormalization of the amplitude of coherent tunneling is used for a
quantitative description of the peculiarities of sound absorption in the
vicinity of critical temperature.Comment: 4 pages, LaTeX, 2 Postscript figures corrected, submitted to Low
Temp. Phy
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