12,952 research outputs found
Feasibility study of a procedure to detect and warn of low level wind shear
A Doppler radar system which provides an aircraft with advanced warning of longitudinal wind shear is described. This system uses a Doppler radar beamed along the glide slope linked with an on line microprocessor containing a two dimensional, three degree of freedom model of the motion of an aircraft including pilot/autopilot control. The Doppler measured longitudinal glide slope winds are entered into the aircraft motion model, and a simulated controlled aircraft trajectory is calculated. Several flight path deterioration parameters are calculated from the computed aircraft trajectory information. The aircraft trajectory program, pilot control models, and the flight path deterioration parameters are discussed. The performance of the computer model and a test pilot in a flight simulator through longitudinal and vertical wind fields characteristic of a thunderstorm wind field are compared
Periodicity of high-order functions in the CNS Final progress report, year ending 30 Jun. 1971
Analysis of cerebral slow potentials underlying human attentive processes in central nervous syste
Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering
We report measurements of the magnetic excitation spectrum of the layered
antiferromagnet La2CoO4 by time-of-flight neutron inelastic scattering. In the
energy range probed in our experiments (0-250 meV) the magnetic spectrum
consists of spin-wave modes with strong in-plane dispersion extending up to 60
meV, and a nearly dispersionless peak at 190 meV. The spin-wave modes exhibit a
small (~1 meV) dispersion along the magnetic zone boundary. We show that the
magnetic spectrum can be described very well by a model of a Heisenberg
antiferromagnet that includes the full spin and orbital degrees of freedom of
Co2+ in an axially-distorted crystal field. The collective magnetic dynamics
are found to be controlled by dominant nearest-neighbour exchange interactions,
strong XY-like single-ion anisotropy and a substantial unquenched orbital
angular momentum.Comment: 8 pages, 7 figure
Boosting Higgs pair production in the final state with multivariate techniques
The measurement of Higgs pair production will be a cornerstone of the LHC
program in the coming years. Double Higgs production provides a crucial window
upon the mechanism of electroweak symmetry breaking and has a unique
sensitivity to the Higgs trilinear coupling. We study the feasibility of a
measurement of Higgs pair production in the final state at
the LHC. Our analysis is based on a combination of traditional cut-based
methods with state-of-the-art multivariate techniques. We account for all
relevant backgrounds, including the contributions from light and charm jet
mis-identification, which are ultimately comparable in size to the irreducible
QCD background. We demonstrate the robustness of our analysis strategy in
a high pileup environment. For an integrated luminosity of
ab, a signal significance of is obtained,
indicating that the final state alone could allow for the
observation of double Higgs production at the High-Luminosity LHC.Comment: 47 pages, 22 figures. v2: updated references, added comparison of
post-MVA kinematic distributions. v3: matches published version in EPJ
The central role of taxonomy in the study of neotropical biodiversity1
© 2020 Missouri Botanical Garden. All rights reserved. The Neotropics are the most species-rich area of the planet. Understanding the origin and maintenance of this diversity is an important goal of ecology and evolutionary biology. Success in this endeavor relies heavily on the past work of taxonomists who have collected specimens and produced the floras and monographs that constitute the foundation for the study of plant diversity. To illustrate this, we visualize collecting efforts through time and identify the importance of past taxonomic and collection efforts in generating the bulk of specimen data that broad-scale analyses rely on today. To demonstrate the importance of taxonomy for the study of Neotropical biodiversity, we showcase selected plant groups in which in-depth taxonomic understanding has facilitated exciting evolutionary and ecological research and highlight the teams of scientists who have built on the legacy of Alwyn Gentry, one of the most prolific taxonomists of the late 20th century. We also discuss challenges faced by taxonomists, including perceived subjectivity, difficulty in measuring impact, and the need to become more interdisciplinary. We end with potential solutions going forward, including integration of taxonomists in interdisciplinary research, advocacy for continued collection efforts, increased funding for alpha taxonomic research that is performed with increasingly replicable methodology, and explicit decolonization efforts to increase inclusivity and equity in the field of taxonomy. Acknowledging the central role of taxonomy and taxonomists is essential to accurately and completely describe Neotropical biodiversity patterns in an age of unprecedented extinction risk and conservation need
Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source
The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 107. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays
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