24,671 research outputs found
Scattering matrices and affine Hecke algebras
We construct the scattering matrices for an arbitrary Weyl group in terms of
elementary operators which obey the generalised Yang-Baxter equation. We use
this construction to obtain the affine Hecke algebras. The center of the affine
Hecke algebras coincides with commuting Hamiltonians. These Hamiltonians have
q-deformed affine Lie algebras as symmetry algebra.Comment: 22 pages, harvmac, no figures, Lecture at Schladming, March 4,11 199
A method for estimating the rate of shedding of tags from yellowfin tuna
ENGLISH: The present paper describes a new method for estimating the shedding rate of tags. The method utilizes not only data on tagging and recovery of fish marked with two tags but also data from those marked with one. One important advantage of the new technique is that the estimates of the shedding rates are free from distortion caused by variations in fishing intensity during the total recovery period. The idea of this method appears to be implicit in a short note by Gulland (1963). This technique has been applied to the data obtained by the Inter-American Tropical Tuna Commission in a tagging cruise off the west coast of southern Baja California, during June 1963, at which time both single and double-tagged yellowfin tuna were released. Details of the tagging procedure and equipment have been described by Fink (1965b). The results presented in the present paper are for yellowfin tuna tagged with dart tags. Estimates of shedding should be made separately for each species investigated and also for each type of tag used, since these rates may be variable and often unexpectedly high (Springer and McErlean 1961, Chadwick 1963).
SPANISH: El presente estudio describe un nuevo método para estimar las tasas del desprendimiento de marcas. El método emplea no solamente los datos sobre la marcación y recobro de peces marcados con dos marcas, pero también datos de los peces marcados con una marca. Una ventaja importante de la nueva técnica, es que las estimaciones de las tasas de desprendimiento son libres de alteración, causada por las variaciones en la intensidad de pesca durante el perÃodo total de recobro. La idea de este método parece ser implÃcita en un breve apunte por Gulland (1963). Esta técnica se ha aplicado a los datos obtenidos por la Comisión Interamericana del Atún Tropical, en un crucero de marcación efectuado frente a la costa occidental al sur de Baja California, en junio de 1963, tiempo en el cual fueron liberados atunes aleta amarilla marcados tanto con una como con dos marcas. Los detalles del procedimiento de la marcación y del equipo usado han sido descritos por Fink (1965b). Los resultados presentados en este estudio, pertenecen al atún aleta amarilla marcado con marcas de dardo. Las estimaciones del desprendimiento deben efectuarse separadamente para cada especie que ha sido investigada y también para cada tipo de marca usado, ya que estas tasas pueden ser vaiables, y a menudo inesperadamente altas (Springer y McErlean 1961, Chadwick 1963).
(PDF contains 20 pages.
A method for estimating the rate of shedding of tags from yellowfin tuna
ENGLISH: The present paper describes a new method for estimating the shedding rate of tags. The method utilizes not only data on tagging and recovery of fish marked with two tags but also data from those marked with one. One important advantage of the new technique is that the estimates of the shedding rates are free from distortion caused by variations in fishing intensity during the total recovery period. The idea of this method appears to be implicit in a short note by Gulland (1963). This technique has been applied to the data obtained by the Inter-American Tropical Tuna Commission in a tagging cruise off the west coast of southern Baja California, during June 1963, at which time both single and double-tagged yellowfin tuna were released. Details of the tagging procedure and equipment have been described by Fink (1965b). The results presented in the present paper are for yellowfin tuna tagged with dart tags. Estimates of shedding should be made separately for each species investigated and also for each type of tag used, since these rates may be variable and often unexpectedly high (Springer and McErlean 1961, Chadwick 1963).
SPANISH: El presente estudio describe un nuevo método para estimar las tasas del desprendimiento de marcas. El método emplea no solamente los datos sobre la marcación y recobro de peces marcados con dos marcas, pero también datos de los peces marcados con una marca. Una ventaja importante de la nueva técnica, es que las estimaciones de las tasas de desprendimiento son libres de alteración, causada por las variaciones en la intensidad de pesca durante el perÃodo total de recobro. La idea de este método parece ser implÃcita en un breve apunte por Gulland (1963). Esta técnica se ha aplicado a los datos obtenidos por la Comisión Interamericana del Atún Tropical, en un crucero de marcación efectuado frente a la costa occidental al sur de Baja California, en junio de 1963, tiempo en el cual fueron liberados atunes aleta amarilla marcados tanto con una como con dos marcas. Los detalles del procedimiento de la marcación y del equipo usado han sido descritos por Fink (1965b). Los resultados presentados en este estudio, pertenecen al atún aleta amarilla marcado con marcas de dardo. Las estimaciones del desprendimiento deben efectuarse separadamente para cada especie que ha sido investigada y también para cada tipo de marca usado, ya que estas tasas pueden ser vaiables, y a menudo inesperadamente altas (Springer y McErlean 1961, Chadwick 1963).
(PDF contains 20 pages.
Inverse turbulent cascades and conformally invariant curves
We offer a new example of conformal invariance far from equilibrium -- the
inverse cascade of Surface Quasi-Geostrophic (SQG) turbulence. We show that
temperature isolines are statistically equivalent to curves that can be mapped
into a one-dimensional Brownian walk (called Schramm-Loewner Evolution or
SLE). The diffusivity is close to , that is iso-temperature
curves belong to the same universality class as domain walls in the O(2) spin
model. Several statistics of temperature clusters and isolines are measured and
shown to be consistent with the theoretical expectations for such a spin system
at criticality. We also show that the direct cascade in two-dimensional
Navier-Stokes turbulence is not conformal invariant. The emerging picture is
that conformal invariance may be expected for inverse turbulent cascades of
strongly interacting systems.Comment: 4 pages, 6 figure
Physical Optics of Invertebrate Eyes
Contains research objectives.Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 36-039-AMC-03200(E
The reaction pi N -> pi pi N in chiral effective field theory with explicit Delta(1232) degrees of freedom
The reaction pi N -> pi pi N is studied at tree level up to next-to-leading
order in the framework of manifestly covariant baryon chiral perturbation
theory with explicit Delta(1232) degrees of freedom. Using total cross section
data to determine the relevant low-energy constants, predictions are made for
various differential as well as total cross sections at higher energies. A
detailed comparison of results based on the heavy-baryon and relativistic
formulations of chiral perturbation theory with and without explicit Delta
degrees of freedom is given.Comment: 30 pages, 13 figure
Chiral Prediction for the Scattering Length to Order
We evaluate the S-wave pion--nucleon scattering length in the framework
of heavy baryon chiral perturbation theory up--to--and--including terms of
order . We show that the order piece of the isovector
amplitude at threshold, , vanishes exactly. We predict for the
isovector scattering length, .Comment: 5 pp, LaTeX file, 2 figures (appended as separate compressed tar
file, amin.uu
Advanced optimal extraction for the Spitzer/IRS
We present new advances in the spectral extraction of point-like sources
adapted to the Infrared Spectrograph onboard the Spitzer Space Telescope. For
the first time, we created a super-sampled point spread function of the
low-resolution modules. We describe how to use the point spread function to
perform optimal extraction of a single source and of multiple sources within
the slit. We also examine the case of the optimal extraction of one or several
sources with a complex background. The new algorithms are gathered in a plugin
called Adopt which is part of the SMART data analysis software.Comment: Accepted for publication in PAS
A review of the population structure of yellowfin tuna, Thunnus albacares, in the Eastern Pacific Ocean
ENGLISH: Since its inception in 1950 by agreement between the Republic of Costa Rica and the United States of America, the Inter-American Tropical Tuna Commission has been engaged in studies of the biology, ecology and population dynamics of yellowfin tuna in the eastern Pacific Ocean. Prime consideration has been given to the evaluation of the effects of fishing pressure on the yellowfin tuna in this area in order to estimate the maximum sustainable yield. A portion of the eastern Pacific has been defined by the Inter-American Tropical Tuna Commission (1963) as a regulatory area for yellowfin tuna (Figure 1). SPANISH: Desde su incepción en 1950, por un acuerdo entre la República de Costa Rica y los Estados Unidos de América, la Comisión Interamericana del Atún Tropical ha estado ocupada en los estudios de la biologÃa, ecologÃa y dinámica de las poblaciones del atún aleta amarilla en el Océano PacÃfico Oriental. Se consideró primariamente la evaluación de los efectos de la
presión de la pesquerÃa sobre el atún aleta amarilla en esta área, para poder estimar el rendimiento máximo sostenible. Una parte del PacÃfico Oriental ha sido definida por la Comisión Interamericana del Atún Tropical (1963), como área de reglamentación del atún aleta amarilla (Figura 1).
(PDF contains 60 pages.
Computing the Loewner driving process of random curves in the half plane
We simulate several models of random curves in the half plane and numerically
compute their stochastic driving process (as given by the Loewner equation).
Our models include models whose scaling limit is the Schramm-Loewner evolution
(SLE) and models for which it is not. We study several tests of whether the
driving process is Brownian motion. We find that just testing the normality of
the process at a fixed time is not effective at determining if the process is
Brownian motion. Tests that involve the independence of the increments of
Brownian motion are much more effective. We also study the zipper algorithm for
numerically computing the driving function of a simple curve. We give an
implementation of this algorithm which runs in a time O(N^1.35) rather than the
usual O(N^2), where N is the number of points on the curve.Comment: 20 pages, 4 figures. Changes to second version: added new paragraph
to conclusion section; improved figures cosmeticall
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