84,882 research outputs found
Evaluation of enzyme immunoassays in the diagnosis of camel (Camelus dromedarius) trypanosomiasis:a preliminary investigation
Three enzyme immunoassays were used for the serodiagnosis of Trypanosoma evansi in camels in the Sudan in order to evaluate their ability to discriminate between infected and non-infected animals. Two assays were used for the detection of trypanosomal antibodies, one using specific anti-camel IgG conjugate and another using a non-specific Protein A conjugate. The third assay detected the presence of trypanosomal antigens using anti-T. evansi antibodies in a double antibody sandwich assay. Inspection of the frequency distribution of assay results suggested that the ELISA for circulating trypanosomal antibodies using specific antisera and the ELISA for circulating antigens can distinguish between non-infected camels and infected camels exhibiting patent infections or not. The ELISA using Protein A conjugate to bind non-specifically to camel immunoglobulin did not appear to discriminate between infected and non-infected animals
Bose-Einstein condensates with attractive 1/r interaction: The case of self-trapping
Amplifying on a proposal by O'Dell et al. for the realization of
Bose-Einstein condensates of neutral atoms with attractive interaction,
we point out that the instance of self-trapping of the condensate, without
external trap potential, is physically best understood by introducing
appropriate "atomic" units. This reveals a remarkable scaling property: the
physics of the condensate depends only on the two parameters and
, where is the particle number, the scattering length,
the "Bohr" radius and the trap frequency in atomic units. We
calculate accurate numerical results for self-trapping wave functions and
potentials, for energies, sizes and peak densities, and compare with previous
variational results. As a novel feature we point out the existence of a second
solution of the extended Gross-Pitaevskii equation for negative scattering
lengths, with and without trapping potential, which is born together with the
ground state in a tangent bifurcation. This indicates the existence of an
unstable collectively excited state of the condensate for negative scattering
lengths.Comment: 7 pages, 7 figures, to appear in Phys. Rev.
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Refinement and preliminary evaluation of two tablet-based tests of real-world visual function
PURPOSE: To describe, refine, evaluate, and provide normative control data for two freely available tablet-based tests of real-world visual function, using a cohort of young, normally-sighted adults.
METHODS: Fifty young (18-40Â years), normally-sighted adults completed tablet-based assessments of (1) face discrimination and (2) visual search. Each test was performed twice, to assess test-retest repeatability. Post-hoc analyses were performed to determine the number of trials required to obtain stable estimates of performance. Distributions were fitted to the normative data to determine the 99% population-boundary for normally sighted observers. Participants were also asked to rate their comprehension of each test.
RESULTS: Both tests provided stable estimates in around 20 trials (~1-4Â min), with only a further reduction of 14%-17% in the 95% Coefficient of Repeatability (CoR95 ) when an additional 40 trials were included. When using only ~20 trials: median durations for the first run of each test were 191Â s (Faces) and 51Â s (Search); test-retest CoR95 were 0.27Â d (Faces) and 0.84Â s (Search); and normative 99% population-limits were 3.50Â d (Faces) and 3.1Â s (Search). No participants exhibited any difficulties completing either test (100% completion rate), and ratings of task-understanding were high (Faces: 9.6 out of 10; Search: 9.7 out of 10).
CONCLUSIONS: This preliminary assessment indicated that both tablet-based tests are able to provide simple, quick, and easy-to-administer measures of real-world visual function in normally-sighted young adults. Further work is required to assess their accuracy and utility in older people and individuals with visual impairment. Potential applications are discussed, including their use in clinic waiting rooms, and as an objective complement to Patient Reported Outcome Measures (PROMs)
Effects of nano-void density, size, and spatial population on thermal conductivity: a case study of GaN crystal
The thermal conductivity of a crystal is sensitive to the presence of
surfaces and nanoscale defects. While this opens tremendous opportunities to
tailor thermal conductivity, a true "phonon engineering" of nanocrystals for a
specific electronic or thermoelectric application can only be achieved when the
dependence of thermal conductivity on the defect density, size, and spatial
population is understood and quantified. Unfortunately, experimental studies of
effects of nanoscale defects are quite challenging. While molecular dynamics
simulations are effective in calculating thermal conductivity, the defect
density range that can be explored with feasible computing resources is
unrealistically high. As a result, previous work has not generated a fully
detailed understanding of the dependence of thermal conductivity on nanoscale
defects. Using GaN as an example, we have combined physically-motivated
analytical model and highly-converged large scale molecular dynamics
simulations to study effects of defects on thermal conductivity. An analytical
expression for thermal conductivity as a function of void density, size, and
population has been derived and corroborated with the model, simulations, and
experiments
Radiative Leptonic Decays
We analyze the radiative leptonic decay mode:
() using a QCD-inspired constituent quark model. The prediction:
makes this channel
experimentally promising in view of the large number of mesons which are
expected to be produced at the future hadron facilities.Comment: LaTex, 12 pages, 2 figures. A discussion on gauge invariance added.
Numerical results update
Achieving diffraction-limited performance on the Berkeley MET5
The Berkeley MET5, funded by EUREKA, is a 0.5-NA EUV projection lithography tool located at the Advanced Light Source at Berkeley National Lab. Wavefront measurements of the MET5 optic have been performed using a custom in-situ lateral shearing interferometer suitable for high-NA interferometry. In this paper, we report on the most recent characterization of the MET5 optic demonstrating an RMS wavefront 0.31 nm, and discuss the specialized mask patterns, gratings, and illumination geometries that were employed to accommodate the many challenges associated with high-NA EUV interferometry
Nonlinear ac response of anisotropic composites
When a suspension consisting of dielectric particles having nonlinear
characteristics is subjected to a sinusoidal (ac) field, the electrical
response will in general consist of ac fields at frequencies of the
higher-order harmonics. These ac responses will also be anisotropic. In this
work, a self-consistent formalism has been employed to compute the induced
dipole moment for suspensions in which the suspended particles have nonlinear
characteristics, in an attempt to investigate the anisotropy in the ac
response. The results showed that the harmonics of the induced dipole moment
and the local electric field are both increased as the anisotropy increases for
the longitudinal field case, while the harmonics are decreased as the
anisotropy increases for the transverse field case. These results are
qualitatively understood with the spectral representation. Thus, by measuring
the ac responses both parallel and perpendicular to the uniaxial anisotropic
axis of the field-induced structures, it is possible to perform a real-time
monitoring of the field-induced aggregation process.Comment: 14 pages and 4 eps figure
Computer generated animation and movie production at LARC: A case study
The process of producing computer generated 16mm movies using the MOVIE.BYU software package developed by Brigham Young University and the currently available hardware technology at the Langley Research Center is described. A general overview relates the procedures to a specific application. Details are provided which describe the data used, preparation of a storyboard, key frame generation, the actual animation, title generation, filming, and processing/developing the final product. Problems encountered in each of these areas are identified. Both hardware and software problems are discussed along with proposed solutions and recommendations
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