527 research outputs found
Kinetic simulations of X-B and O-X-B mode conversion
We have performed fully-kinetic simulations of X-B and O-X-B mode conversion
in one and two dimensional setups using the PIC code EPOCH. We have recovered
the linear dispersion relation for electron Bernstein waves by employing
relatively low amplitude incoming waves. The setups presented here can be used
to study non-linear regimes of X-B and O-X-B mode conversion.Comment: 4 pages, 3 figure
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The use of an intermediate wavelength laser for alignment to inertial confinement fusion targets
The conceptual design of the National Ignition Facility (NIF) 192 beam laser incorporates a low-power alignment beam injected in the pinhole plane of the final spatial filter with a wave length intermediate between the 1053 mn laser output and the 351 mn frequency-converted beam that illuminates the target Choosing the specific wavelength for which the spatial filter plane is reimaged in the same target chamber plane as the frequency-converted main laser pulse, achieves optimum accuracy without the need for additional means to insure precise overlap between the two beams. Insertion of the alignment beam after the last laser amplifier also allows alignment to the target while the amplifiers are still cooling from a previous shot
NeuroSpeech
NeuroSpeech is a software for modeling pathological speech signals considering different speech dimensions: phonation, articulation, prosody, and intelligibility. Although it was developed to model dysarthric speech signals from Parkinson's patients, its structure allows other computer scientists or developers to include other pathologies and/or measures. Different tasks can be performed: (1) modeling of the signals considering the aforementioned speech dimensions, (2) automatic discrimination of Parkinson's vs. non-Parkinson's, and (3) prediction of the neurological state according to the Unified Parkinson's Disease Rating Scale (UPDRS) score. The prediction of the dysarthria level according to the Frenchay Dysarthria Assessment scale is also provided
Aerodynamic investigations of ventilated brake discs.
The heat dissipation and performance of a ventilated brake disc strongly depends
on the aerodynamic characteristics of the flow through the rotor passages. The
aim of this investigation was to provide an improved understanding of ventilated
brake rotor flow phenomena, with a view to improving heat dissipation, as well
as providing a measurement data set for validation of computational fluid
dynamics methods. The flow fields at the exit of four different brake rotor
geometries, rotated in free air, were measured using a five-hole pressure probe
and a hot-wire anemometry system. The principal measurements were taken using
two-component hot-wire techniques and were used to determine mean and unsteady
flow characteristics at the exit of the brake rotors. Using phase-locked data
processing, it was possible to reveal the spatial and temporal flow variation
within individual rotor passages. The effects of disc geometry and rotational
speed on the mean flow, passage turbulence intensity, and mass flow were
determined. The rotor exit jet and wake flow were clearly observed as
characterized by the passage geometry as well as definite regions of high and
low turbulence. The aerodynamic flow characteristics were found to be reasonably
independent of rotational speed but highly dependent upon rotor geometry
Behavioral metabolomics analysis identifies novel neurochemical signatures in methamphetamine sensitization: Methamphetamine sensitization metabolomics
Behavioral sensitization has been widely studied in animal models and is theorized to reflect neural modifications associated with human psychostimulant addiction. While the mesolimbic dopaminergic pathway is known to play a role, the neurochemical mechanisms underlying behavioral sensitization remain incompletely understood. In the present study, we conducted the first metabolomics analysis to globally characterize neurochemical differences associated with behavioral sensitization. Methamphetamine-induced sensitization measures were generated by statistically modeling longitudinal activity data for eight inbred strains of mice. Subsequent to behavioral testing, nontargeted liquid and gas chromatography-mass spectrometry profiling was performed on 48 brain samples, yielding 301 metabolite levels per sample after quality control. Association testing between metabolite levels and three primary dimensions of behavioral sensitization (total distance, stereotypy and margin time) showed four robust, significant associations at a stringent metabolome-wide significance threshold (false discovery rate < 0.05). Results implicated homocarnosine, a dipeptide of GABA and histidine, in total distance sensitization, GABA metabolite 4-guanidinobutanoate and pantothenate in stereotypy sensitization, and myo-inositol in margin time sensitization. Secondary analyses indicated that these associations were independent of concurrent methamphetamine levels and, with the exception of the myo-inositol association, suggest a mechanism whereby strain-based genetic variation produces specific baseline neurochemical differences that substantially influence the magnitude of MA-induced sensitization. These findings demonstrate the utility of mouse metabolomics for identifying novel biomarkers, and developing more comprehensive neurochemical models, of psychostimulant sensitization
Influence of plasma turbulence on microwave propagation
It is not fully understood how electromagnetic waves propagate through plasma
density fluctuations when the size of the fluctuations is comparable with the
wavelength of the incident radiation. In this paper, the perturbing effect of a
turbulent plasma density layer on a traversing microwave beam is simulated with
full-wave simulations. The deterioration of the microwave beam is calculated as
a function of the characteristic turbulence structure size, the turbulence
amplitude, the depth of the interaction zone and the size of the waist of the
incident beam. The maximum scattering is observed for a structure size on the
order of half the vacuum wavelength. The scattering and beam broadening was
found to increase linearly with the depth of the turbulence layer and
quadratically with the fluctuation strength. Consequences for experiments and
3D effects are considered.Comment: 16 pages, 13 figures. This is an author-created, un-copyedited
version of an article submitted for publication in Plasma Physics and
Controlled Fusion. IoP Publishing Ltd is not responsible for any errors or
omissions in this version of the manuscript or any version derived from i
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