50,111 research outputs found
A New Technique for System-to-system Transfer of Surface Data
The purpose is to describe a recently developed technique aimed at providing a universal interface between surface types. In brief, a software package was developed which functions a common denominator of CAD/CAM surface types. This software enable one to convert from any given surface representation to any other target representation. The tiles maintain the same slope continuity as the target surface gram, bicubic patches are used since they allow one to match point, slope, and twist vectors to the target surface. Thus, slopes can be continuous or discontinuous as they are on the target surface. The patches can be of lower order if desired. For example, if only point information is available, the patches produced will be bilinear; however, the number of patches required is likely to increase correspondingly. The patches can be of higher order although many systems will not accept patches of more than order four. The final result of the program is a rectangular grid of bicubic patches. The patches fit the target surface exactly at their corners. Also, the patch corners have the same tangent and twist vectors. Adjacent patches will have slope continuity, unless a discontinuity was indicated by the target surface
Ionosphere/microwave beam interaction study
A solar power satellite microwave power density of 20mw sq cm was confirmed as the level where nonlinear interactions may occur in the ionosphere, particularly at 100 km altitude. Radio wave heating at this altitude, produced at the Arecibo Observatory, yielded negative results for radio wave heating of an underdense ionosphere. Overdense heating produced striations in the ionosphere which may cause severe radio frequency interference problems under certain conditions. The effects of thermal self-focusing are shown to be limited severely geographically. The aspect sensitivity of field-aligned striations makes interference-free regions above magnetic latitude about 60 deg. A test program is proposed to simulate the interaction of the SPS beam with the ionosphere, to measure the effects of the interaction on the ionosphere and on communication and navigation systems, and to interpret the results
Mollusca of the Illinois River, Arkansas
The Illinois River is in the Ozark region of northwestern Arkansas and eastern Oklahoma. A survey of the Illinois River in Arkansas produced nine species and one morphological subspecies of gastropods, three species of sphaeriid clams, and 23 species of unionid mussels. Museum records resulted in another two species and an ecophenotype of the Unionidae. This represents the first published survey of molluscan species from the Illinois River in Arkansas
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Buddhist-Derived Loving-Kindness and Compassion Meditation for the Treatment of Psychopathology: a Systematic Review
Although clinical interest has predominantly focused on mindfulness meditation, interest into the clinical utility of Buddhist-derived loving-kindness meditation (LKM) and compassion meditation (CM) is also growing. This paper follows the PRISMA (preferred reporting items for systematic reviews and meta-analysis) guidelines and provides an evaluative systematic review of LKM and CM intervention studies. Five electronic academic databases were systematically searched to identify all intervention studies assessing changes in the symptom severity of Diagnostic and Statistical Manual of Mental Disorders (text revision fourth edition) Axis I disorders in clinical samples and/or known concomitants thereof in sub-clinical/healthy samples. The comprehensive database search yielded 342 papers and 20 studies (comprising a total of 1,312 participants) were eligible for inclusion. The Quality Assessment Tool for Quantitative Studies was then used to assess study quality. Participants demonstrated significant improvements across five psychopathology-relevant outcome domains: (i) positive and negative affect, (ii) psychological distress, (iii) positive thinking, (iv) interpersonal relations, and (v) empathic accuracy. It is concluded that LKM and CM interventions may have utility for treating a variety of psychopathologies. However, to overcome obstacles to clinical integration, a lessons-learned approach is recommended whereby issues encountered during the (ongoing) operationalization of mindfulness interventions are duly considered. In particular, there is a need to establish accurate working definitions for LKM and CM
Prompt Photon Plus Jet Photoproduction at HERA at Next-to-Leading Order in QCD
The cross section for photoproduction of an isolated prompt photon in
association with a jet is studied in Next-to-Leading Order. The kinematics are
those appropriate for the DESY collider HERA. The effects on the cross
section of various experimental cuts including isolation cuts on the photon is
examined. Comparisons with the ZEUS preliminary data using two parametrizations
of the photon structure function is made, and good agreement is found. The data
is not yet precise enough to make a distinction between various models for the
photon structure function.Comment: Uses eps
Appropriate surveying methods in the Philippines: Can modern GPS units help?
An investigation was undertaken to test the effectiveness of two procedures for recording boundaries and plot positions for scientific studies on farms on Leyte Island, the Philippines. The accuracy of a Garmin 76 Global Positioning System (GPS) unit and a compass and chain was checked under the same conditions. Tree canopies interfered with the ability of the satellite signal to reach the GPS and therefore the GPS survey was less accurate than the compass and chain survey. Where a high degree of accuracy is required, a compass and chain survey remains the most effective method of surveying land underneath tree canopies, providing operator error is minimised. For a large number of surveys and thus large amounts of data, a GPS is more appropriate than a compass and chain survey because data are easily up-loaded into a Geographic Information System (GIS). However, under dense canopies where satellite signals cannot reach the GPS, it may be necessary to revert to a compass survey or a combination of both methods
Critical Behavior of Light
Light is shown to exhibit critical and tricritical behavior in passive
mode-locked lasers with externally injected pulses. It is a first and unique
example of critical phenomena in a one-dimensional many body light-mode system.
The phase diagrams consist of regimes with continuous wave, driven para-pulses,
spontaneous pulses via mode condensation, and heterogeneous pulses, separated
by phase transition lines which terminate with critical or tricritical points.
Enhanced nongaussian fluctuations and collective dynamics are observed at the
critical and tricritical points, showing a mode system analog of the critical
opalescence phenomenon. The critical exponents are calculated and shown to
comply with the mean field theory, which is rigorous in the light system.Comment: RevTex, 5 pages, 3 figure
Acceleration Of Protons To Above 6 MeV Using H2O >Snow> Nanowire Targets
A scheme is presented for using H2O >snow> nanowire targets for the generation of fast protons. This novel method may relax the requirements for very high laser intensities, thus reducing the size and cost of laser based ion acceleration system.Physic
Production of a Prompt Photon in Association with Charm at Next-to-Leading Order in QCD
A second order, , calculation in perturbative quantum
chromodynamics of the two particle inclusive cross section is presented for the
reaction for large values of the
transverse momentum of the prompt photon and charm quark. The combination of
analytic and Monte Carlo integration methods used here to perform phase-space
integrations facilitates imposition of photon isolation restrictions and other
selections of relevance in experiments. Differential distributions are provided
for various observables. Positive correlations in rapidity are predicted.Comment: 27 pages in RevTex plus 14 figures in one compressed PS fil
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