106,821 research outputs found
Radar studies of bird migration
Observations of bird migration with NASA radars were made at Wallops Island, Va. Simultaneous observations were made at a number of radar sites in the North Atlantic Ocean in an effort to discover what happened to those birds that were observed leaving the coast of North America headed toward Bermuda, the Caribbean and South America. Transatlantic migration, utilizing observations from a large number of radars is discussed. Detailed studies of bird movements at Wallops Island are presented
SU3 isoscalar factors
A summary of the properties of the Wigner Clebsch-Gordan coefficients and
isoscalar factors for the group SU3 in the SU2U1 decomposition is
presented. The outer degeneracy problem is discussed in detail with a proof of
a conjecture (Braunschweig's) which has been the basis of previous work on the
SU3 coupling coefficients. Recursion relations obeyed by the SU3 isoscalar
factors are produced, along with an algorithm which allows numerical
determination of the factors from the recursion relations. The algorithm
produces isoscalar factors which share all the symmetry properties under
permutation of states and conjugation which are familiar from the SU2 case. The
full set of symmetry properties for the SU3 Wigner-Clebsch-Gordan coefficients
and isoscalar factors are displayed.Comment: 20 pages, LaTeX (earlier version incomplete
Neotropical Bird Migration During The Ice Ages: Orientation And Ecology
Reconstruction of breeding habitat of North American Neotropical migrants 18,000 years ago and 9,000 years ago indicated major shifts in both location and composition of plant communities relative to present conditions. Increased vegetation in xeric areas may have compensated, at least in part, for the reduction in breeding habitat due to glaciation. Autumnal flights of Neotropical passerine migrants flying on constant headings from North America to Central and South America were simulated under present wind conditions and for winds during periods of glaciation at 18,000 and 9,000 years ago. The 155 degrees average headings currently observed for Atlantic migrants were found to function well during periods of glaciation and may have been more generally useful during those times than at present
Population imbalanced fermions in harmonically trapped optical lattices
The attractive Fermi-Hubbard Hamiltonian is solved via the Bogoliubov-de
Gennes formalism to analyze the ground state phases of population imbalanced
fermion mixtures in harmonically trapped two-dimensional optical lattices. In
the low density limit the superfluid order parameter modulates in the radial
direction towards the trap edges to accommodate the unpaired fermions that are
pushed away from the trap center with a single peak in their density. However
in the high density limit while the order parameter modulates in the radial
direction towards the trap center for low imbalance, it also modulates towards
the trap edges with increasing imbalance until the superfluid to normal phase
transition occurs beyond a critical imbalance. This leads to a single peak in
the density of unpaired fermions for low and high imbalance but leads to double
peaks for intermediate imbalance.Comment: 4 pages with 4 figures, accepted to appear in PR
The control of nonlinear stochastic control systems under discounted performance criteria
Control algorithm for optimization of nonlinear stochastic processes with discounted performance criteri
Older people, regeneration and health and well-being. Case study of Salford Partnership Board for Older People
This study sat within a national project aimed at demonstrating that expert knowledge housed within universities can make a positive impact in urban communities around four themes: Community Cohesion, Crime, Enterprise and Health & Wellbeing. It involved the Universities of Salford, Northumbria, Central Lancashire, Manchester Metropolitan University and Bradford. The project aimed to address key urban regeneration challenges in the North of England through inter-disciplinary collaboration between partner universities and practitioner organisations. It also sought to build a long term strategic alliance between core university partners.
Within each of the four project areas there were a number of smaller projects each focusing on the relationship between the theme and urban regeneration.
This study sought to establish how partnership boards for older people address the health and well being needs of people over 50 years of age including how health and wellbeing are defined; strategies older people adopt to change service providers' actions; learning by service providers about the involvement of older people on Boards; and how this influences practice. The main activity within this study was to interview Salford Partnership Board members. The findings informed further development of the Board
Monetary Policy Under Uncertainty in Micro-Founded Macroeconometric Models
We use a micro-founded macroeconometric modeling framework to investigate the design of monetary policy when the central bank faces uncertainty about the true structure of the economy. We apply Bayesian methods to estimate the parameters of the baseline specification using postwar U.S. data, and then determine the policy under commitment that maximizes household welfare. We find that the performance of the optimal policy is closely matched by a simple operational rule that focuses solely on stabilizing nominal wage inflation. Furthermore, this simple wage stabilization rule is remarkably robust to uncertainty about the model parameters and to various assumptions regarding the nature and incidence of the innovations. However, the characteristics of optimal policy are very sensitive to the specification of the wage contracting mechanism, thereby highlighting the importance of additional research regarding the structure of labor markets and wage determination.
Neutrino Electromagnetic Form Factor and Oscillation Effects on Neutrino Interaction With Dense Matter
The mean free path of neutrino - free electron gas interaction has been
calculated by taking into account the neutrino electromagnetic form factors and
the possibility of neutrino oscillation. It is shown that the form factor
effect becomes significant for a neutrino magnetic moment \mu_\nu > 10^{-10}
mu_B and for a neutrino radius R > 10^{-6} MeV^{-1}. The mean free path is
found to be sensitive to the nu_e-nu_mu and nu_e-nu_e^R transition
probabilities.Comment: 4 pages, 3 eps figures, accepted for publication in Phys. Rev.
Neutron Fraction and Neutrino Mean Free Path Predictions in Relativistic Mean Field Models
The equation of state (EOS) of dense matter and neutrino mean free path
(NMFP) in a neutron star have been studied by using relativistic mean field
models motivated by effective field theory (ERMF). It is found that the models
predict too large proton fractions, although one of the models (G2) predicts an
acceptable EOS. This is caused by the isovector terms. Except G2, the other two
models predict anomalous NMFP. In order to minimize the anomaly, besides an
acceptable EOS, a large M* is favorable. A model with large M* retains the
regularity in the NMFP even for a small neutron fraction.Comment: 4 pages, 5 figures, accepted for publication in Phys. Rev.
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