3,133 research outputs found
An early Anglo-Saxon bridle-fitting from South Leckaway, Forfar, Angus, Scotland
[FIRST PARAGRAPH] In February 2003 the Kinnettles Heritage Group made a quite unexpected find during field-walking at South Leckaway farm near Forfar, Angus (NGR NO 4379 4810): the most northerly example in Britain — by about 150 miles — of an Anglo- Saxon object decorated in Salin’s Style I. It lay isolated and face down on the surface. A follow-up field-walk at the end of the month confirmed, partly with the aid of a metal detector, that there were no readily apparent additional pieces of metalwork, associated structures or burial evidence. The find was reported under the Scottish Treasure Trove legislation, duly claimed and allocated in June 2003 to the Meffan Institute, Forfar (part of Angus Cultural Services)
Numerical simulation of dark lanes in post-flare supra-arcade
We integrate the MHD ideal equations to simulate dark void sunwardly moving
structures in post--flare supra--arcades. We study the onset and evolution of
the internal plasma instability to compare with observations and to gain
insight into physical processes and characteristic parameters of these
phenomena. The numerical approach uses a finite-volume Harten-Yee TVD scheme to
integrate the 1D1/2 MHD equations specially designed to capture supersonic flow
discontinuities. The integration is performed in both directions, the sunward
radial one and the transverse to the magnetic field. For the first time, we
numerically reproduce observational dark voids described in Verwichte et al.
(2005). We show that the dark tracks are plasma vacuums generated by the
bouncing and interfering of shocks and expansion waves, upstream an initial
slow magnetoacoustic shock produced by a localized deposition of energy modeled
with a pressure perturbation. The same pressure perturbation produces a
transverse to the field or perpendicular magnetic shock giving rise to
nonlinear waves that compose the kink--like plasma void structures, with the
same functional sunward decreasing phase speed and constancy with height of the
period, as those determined by the observations.Comment: Accepted MNRAS, 6 pages, 7 figure
New hydrogen-like potentials
Using the modified factorization method introduced by Mielnik, we construct a
new class of radial potentials whose spectrum for l=0 coincides exactly with
that of the hydrogen atom. A limiting case of our family coincides with the
potentials previously derived by Abraham and MosesComment: 6 pages, latex, 2 Postscript figure
Heuristic-based firefly algorithm for bound constrained nonlinear binary optimization
Firefly algorithm (FA) is a metaheuristic for global optimization. In this paper,we address the practical testing of aheuristic-based FA (HBFA) for computing optimaof discrete nonlinear optimization problems,where the discrete variables are of binary type. An important issue in FA is the formulation of attractiveness of each firefly which in turn affects its movement in the search space. Dynamic updating schemes are proposed for two parameters, one from the attractiveness term and the other from the randomization term. Three simple heuristics capable of transforming real continuous variables into binary ones are analyzed. A new sigmoid ‘erf’ function is proposed. In the context of FA, three different implementations to incorporate the heuristics for binary variables into the algorithm are proposed. Based on a set of benchmark problems, a comparison is carried out with other binary dealing metaheuristics. The results demonstrate that the proposed HBFA is efficient and outperforms binary versions of differential evolution (DE) and particle swarm optimization (PSO). The HBFA also compares very favorably with angle modulated version of DE and PSO. It is shown that the variant of HBFA based on the sigmoid ‘erf’ function with ‘movements in continuous space’ is the best, both in terms of computational requirements and accuracy.Fundação para a Ciência e a Tecnologia (FCT
Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams ? qualitative analysis of QP echoes
International audienceThe wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr), with different zenith angle ? and azimuth angle ?, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period ?. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out
First record of the myrmicine ant genus Paedalgus Forel, 1911 (Hymenoptera: Formicidae) from the Western Hemisphere
Fern\ue1ndez F. 2002. First record of the myrmicine ant genus
Paedalgus Forel, 1911 (Hymenoptera: Formicidae) from the Western
Hemisphere. Entomotropica 17(2):181-182. The myrmicine ant genus
Paedalgus Forel, 1911 (Hymenoptera: Formicidae) is recorded for the
first time in the Western Hemisphere, based upon several undescribed
species collected in Colombia, Peru and Brazil. The genus was
previously known only from Africa and Sri Lanka.Fern\ue1ndez F. 2002. Primer registro de hormigas Myrmicinae del
g\ue9nero Paedalgus Forel, 1911 (Hymenoptera: Formicidae) del
Hemisferio Occidental. Entomotropica 17(2):181-182. El g\ue9nero de
hormigas Paedalgus Forel, 1911 (Hymenoptera: Formicidae: Myrmicinae) se
registra por primera vez para el Hemisferio Occidental con base en
varias especies no descritas de Colombia, Per\ufa y Brasil. Hasta el
momento el g\ue9nero s\uf3lo se conoc\ueda de Africa y Sri Lanka
Absence of Fragmentation in Two-Dimensional Bose-Einstein Condensation
We investigate the possibility that the BEC-like phenomena recently detected
on two-dimensional finite trapped systems consist of fragmented condensates. We
derive and diagonalize the one-body density matrix of a two-dimensional
isotropically trapped Bose gas at finite temperature. For the ideal gas, the
procedure reproduces the exact harmonic-oscillator eigenfunctions and the Bose
distribution. We use a new collocation-minimization method to study the
interacting gas in the Hartree-Fock approximation and obtain a ground-state
wavefunction and condensate fraction consistent with those obtained by other
methods. The populations of the next few eigenstates increase at the expense of
the ground state but continue to be negligible; this supports the conclusion
that two-dimensional BEC is into a single state.Comment: 6 pages, 1 figur
Nurses\u27 Alumnae Association Bulletin - Volume 2 Number 3
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Letter from the President
Delegates to Biennial Convention
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Blood Transfusion - Plasma Unit
Life in the Army Nurse Corps
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