567 research outputs found
Studies of the effects of industrial pollution in the lower Patapsco river area: 1. Curtis Bay Region 1941
Industrial effluents in the lower Patapsco area, which constitutes the navigable portion of the river and includes Baltimore Harbor, are many and include waste acid, distillery waters, tannery wastes and copper as (ferrous sulphate) from pigment and steel industries. (PDF contains 22 pages (2 on 1
A review of IATTC research on the early life history and reproductive biology of scombrids conducted at the Achotines Laboratory from 1985 to 2005
English:
For nearly a century, fisheries scientists have studied marine fish stocks in an effort to understand how the
abundances of fish populations are determined. During the early lives of marine fishes, survival is
variable, and the numbers of individuals surviving to transitional stages or recruitment are difficult to
predict.
The egg, larval, and juvenile stages of marine fishes are characterized by high rates of mortality and
growth. Most marine fishes, particularly pelagic species, are highly fecund, produce small eggs and
larvae, and feed and grow in complex aquatic ecosystems. The identification of environmental or
biological factors that are most important in controlling survival during the early life stages of marine
fishes is a potentially powerful tool in stock assessment.
Because vital rates (mortality and growth) during the early life stages of marine fishes are high and
variable, small changes in those rates can have profound effects on the properties of survivors and
recruitment potential (Houde 1989). Understanding and predicting the factors that most strongly
influence pre-recruit survival are key goals of fisheries research programs.
Spanish:
Desde hace casi un siglo, los científicos pesqueros han estudiado las poblaciones de peces marinos en un
intento por entender cómo se determina la abundancia de las mismas. Durante la vida temprana de los
peces marinos, la supervivencia es variable, y el número de individuos que sobrevive hasta las etapas
transicionales o el reclutamiento es difícil de predecir.
Las etapas de huevo, larval, y juvenil de los peces marinos son caracterizadas por tasas altas de
mortalidad y crecimiento. La mayoría de los peces marinos, particularmente las especies pelágicas, son
muy fecundos, producen huevos y larvas pequeños, y se alimentan y crecen en ecosistemas acuáticos complejos. La identificación los factores ambientales o biológicos más importantes en el control de la
supervivencia durante las etapas tempranas de vida de los peces marinos es una herramienta
potencialmente potente en la evaluación de las poblaciones.
Ya que las tasas vitales (mortalidad y crecimiento) durante las etapas tempranas de vida de los peces
marinos son altas y variables, cambios pequeños en esas tasas pueden ejercer efectos importantes sobre
las propiedades de los supervivientes y el potencial de reclutamiento (Houde 1989). Comprender y
predecir los factores que más afectan la supervivencia antes del reclutamiento son objetivos clave de los
programas de investigación pesquera
Gaussian Tunneling Model of c-Axis Twist Josephson Junctions
We calculate the critical current density for c-axis Josephson
tunneling between identical high temperature superconductors twisted an angle
about the c-axis. We model the tunneling matrix element squared as a
Gaussian in the change of wavevector q parallel to the junction, . The
obtained for the s- and extended-s-wave order parameters (OP's) are consistent
with the BiSrCaCuO data of Li {\it et al.}, but only
for strongly incoherent tunneling, . A -wave OP
is always inconsistent with the data. In addition, we show that the apparent
conventional sum rule violation observed by Basov et al. might be
understandable in terms of incoherent c-axis tunneling, provided that the OP is
not -wave.Comment: 6 pages, 6 figure
Numerical studies of the two- and three-dimensional gauge glass at low temperature
We present results from Monte Carlo simulations of the two- and
three-dimensional gauge glass at low temperature using the parallel tempering
Monte Carlo method. Our results in two dimensions strongly support the
transition being at T_c=0. A finite-size scaling analysis, which works well
only for the larger sizes and lower temperatures, gives the stiffness exponent
theta = -0.39 +/- 0.03. In three dimensions we find theta = 0.27 +/- 0.01,
compatible with recent results from domain wall renormalization group studies.Comment: 7 pages, 10 figures, submitted to PR
Zero Temperature Glass Transition in the Two-Dimensional Gauge Glass Model
We investigate dynamic scaling properties of the two-dimensional gauge glass
model for the vortex glass phase in superconductors with quenched disorder.
From extensive Monte Carlo simulations we obtain static and dynamic finite
size scaling behavior, where the static simulations use a temperature exchange
method to ensure convergence at low temperatures. Both static and dynamic
scaling of Monte Carlo data is consistent with a glass transition at zero
temperature. We study a dynamic correlation function for the superconducting
order parameter, as well as the phase slip resistance. From the scaling of
these two functions, we find evidence for two distinct diverging correlation
times at the zero temperature glass transition. The longer of these time scales
is associated with phase slip fluctuations across the system that lead to
finite resistance at any finite temperature, while the shorter time scale is
associated with local phase fluctuations.Comment: 8 pages, 10 figures; v2: some minor correction
Coherent electron-phonon coupling and polaron-like transport in molecular wires
We present a technique to calculate the transport properties through
one-dimensional models of molecular wires. The calculations include inelastic
electron scattering due to electron-lattice interaction. The coupling between
the electron and the lattice is crucial to determine the transport properties
in one-dimensional systems subject to Peierls transition since it drives the
transition itself. The electron-phonon coupling is treated as a quantum
coherent process, in the sense that no random dephasing due to electron-phonon
interactions is introduced in the scattering wave functions. We show that
charge carrier injection, even in the tunneling regime, induces lattice
distortions localized around the tunneling electron. The transport in the
molecular wire is due to polaron-like propagation. We show typical examples of
the lattice distortions induced by charge injection into the wire. In the
tunneling regime, the electron transmission is strongly enhanced in comparison
with the case of elastic scattering through the undistorted molecular wire. We
also show that although lattice fluctuations modify the electron transmission
through the wire, the modifications are qualitatively different from those
obtained by the quantum electron-phonon inelastic scattering technique. Our
results should hold in principle for other one-dimensional atomic-scale wires
subject to Peierls transitions.Comment: 21 pages, 8 figures, accepted for publication in Phys. Rev. B (to
appear march 2001
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