Vertical migration during tidal transport of megalopae of Necora puber in coastal shallow waters during daytime

For meroplanktonic larvae that must settle in coastal areas, their successful return to the shore is determined largely by physical transport processes; however, many organisms perform vertical movements to aid successful recruitment. In this study, daytime tidal vertical migration of megalopae of the velvet swimming crab Necora puber was investigated across two different exposures in the shallow waters of Plymouth Sound. Crabs were collected using a plankton net at the surface and near the bottom during flood and ebb tides. Distribution of the pelagic postlarvae was patchy and the abundance varied spatially in tens and thousands of metres. In temporal scales, the annual pattern was dominated by low occurrence of megalopae, punctuated by episodic peaks of high abundance. Most megalopae were collected at the surface irrespective of the tidal phase. The effect of wave exposure on the vertical migration of megalopae was not clear, although there was a general higher abundance of megalopae on exposed shores. Daytime abundance in the water column appears to be regulated by the tidal cycle, as megalopae were more abundant during flood than ebb tides. Although the megalopae do not appear to make large vertical migrations, this behaviour should produce a net shoreward transport. © 2005 Elsevier Ltd. All rights reserved.

Invariant conserved currents in gravity theories with local Lorentz and diffeomorphism symmetry

We discuss conservation laws for gravity theories invariant under general coordinate and local Lorentz transformations. We demonstrate the possibility to formulate these conservation laws in many covariant and noncovariant(ly looking) ways. An interesting mathematical fact underlies such a diversity: there is a certain ambiguity in a definition of the (Lorentz-) covariant generalization of the usual Lie derivative. Using this freedom, we develop a general approach to the construction of invariant conserved currents generated by an arbitrary vector field on the spacetime. This is done in any dimension, for any Lagrangian of the gravitational field and of a (minimally or nonminimally) coupled matter field. A development of the regularization via relocalization scheme is used to obtain finite conserved quantities for asymptotically nonflat solutions. We illustrate how our formalism works by some explicit examples. © 2006 The American Physical Society.

Circulação recente de sedimentos costeiros nas praias de santos durante eventos de tempestades: Dados para a gestão de impactos físicos costeiros

The beachs of Santos are situated in Santos Bay, central portion of paulista coast, in São Paulo state. This beachs are frequently affected by cold fronts with winds and currents from the South. These fronts are responsible for the removal and transport of sediments (sand) in Santos beaches. In order to quantify this sedimentation the channels of Santos were analysed, due to their function as box colectors of sediments during storm events. The channels are filled by sands, which volume in channels 1 to 6 was estimated, by using the length, width and height of sand sedimented in the channels, in the event of 22-27 april 2005. The chanels 2, 3 and 1 presented the larger volumes of sands, confirming that the central and SW portion of the beaches of Santos present higher levels of sedimentation or re-sedimentation. That is due to the transport by ocean waves and currents and currents from the Channel of the Port of Santos. This central portion suffer invasion of marine water over street and buildings, caracterizated of geological rise area.

Propagation of ship waves on a sloping bottom

The numerical model FUNWAVE was adapted in order to simulate the generation and propagation of ship waves to shore, including phenomena such as refraction, diffraction, currents and breaking of waves. Results are shown for Froude numbers equal to 0.8, 1.0 and 1.1, in order to verify the refraction of the wave pattern, identify breaking conditions and to investigate the wave generation scheme as a moving pressure at the free surface. © 2009 World Scientific Publishing Co. Pte. Ltd.

Select bibliography on coastal area development and environmental, physical and regional planning in the Caribbean region

Bibliografía sobre desarrollo de las áreas costeras, planificación del medio ambiente, recursos marinos, planificación regional y física, y puertos del Caribe.

Generalization of Wye and Delta auto-connections: Analysis of voltages and currents

Multipulse rectifier topologies based on autoconnections, or differential connections, are more and more applied as interface stages between the mains and power converters. These topologies mitigate many low-order current harmonics in the utility, reducing the THD (total harmonic distortion) and increasing the power factor. This paper presents a mathematical model based on phasor diagrams, that results in a single expression able to unify all differential topologies connections (Delta and Wye), for both step-up or step-down autotransformers, for 12 and 18-pulse AC-DC converters. The proposed family of converters can be designed for any relationship between the input voltage and the load voltage. An immediate application would be the retrofit, i.e. to replace a conventional rectifier with poor quality of the processed energy by the 12 or 18 pulses rectifier with Wye or Delta-differential connection. The design procedure, simple and fast, is developed and tested for a prototype rating 6 kW and 250 V on the DC load © 2010 IEEE.

Waves generated by two or more ships in a channel

The numerical model FUNWAVE+Ship simulates the generation and propagation of ship waves to shore, including phenomena such as refraction, diffraction, currents and breaking of waves. The interaction of two wave trains, generated by ships moving either in the same direction at different speeds or in opposite directions, is studied. Focus is given to the wave orbital velocities and to the free surface pattern.

Interaction between wave and coastal structure: Validation of two lagrangian numerical models with experimental results marine 2011

Numerical modeling of the interaction among waves and coastal structures is a challenge due to the many nonlinear phenomena involved, such as, wave propagation, wave transformation with water depth, interaction among incident and reflected waves, run-up / run-down and wave overtopping. Numerical models based on Lagrangian formulation, like SPH (Smoothed Particle Hydrodynamics), allow simulating complex free surface flows. The validation of these numerical models is essential, but comparing numerical results with experimental data is not an easy task. In the present paper, two SPH numerical models, SPHysics LNEC and SPH UNESP, are validated comparing the numerical results of waves interacting with a vertical breakwater, with data obtained in physical model tests made in one of the LNEC's flume. To achieve this validation, the experimental set-up is determined to be compatible with the Characteristics of the numerical models. Therefore, the flume dimensions are exactly the same for numerical and physical model and incident wave characteristics are identical, which allows determining the accuracy of the numerical models, particularly regarding two complex phenomena: wave-breaking and impact loads on the breakwater. It is shown that partial renormalization, i.e. renormalization applied only for particles near the structure, seems to be a promising compromise and an original method that allows simultaneously propagating waves, without diffusion, and modeling accurately the pressure field near the structure.

Identification of transmission line parameters from temporal measurements of currents and voltages in their terminals: Influence oh the length line

The objective of this paper is to show a methodology to estimate transmission line parameters. The method is applied in a single-phase transmission line using the method of least squares. In this method the longitudinal and transversal parameters of the line are obtained as a function of a set of measurements of currents and voltages (as well as their derivatives with respect to time) at the terminals of the line during the occurrence of a short-circuit phase-ground near the load. The method is based on the assumption that a transmission line can be represented by a single circuit π. The results show that the precision of the method depends on the length of the line, where it has a better performance for short lines and medium length. © 2012 IEEE.

Search for flavor changing neutral currents in top quark decays in pp collisions at 7 TeV

The results of a search for flavor changing neutral currents in top quark decays t→Zq in events with a topology compatible with the decay chain tt̄→Wb+Zq→ℓνb+ℓℓq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb-1 of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing neutral currents in top quark decays is found. A t→Zq branching fraction greater than 0.21% is excluded at the 95% confidence level. © 2012 CERN.

Checklist of freshwater ichthyofauna from coastal streams of Juréia-Itatins Reserve, Southeastern Brazil

The Juréia-Itatins Ecological Station (JIES) is one of the few protected areas in the state of São Paulo, which harbor a significant portion of the Atlantic forest. Although there is high diversity and endemism of fish species in this region, knowledge of the ichthyofauna in JIES is incipient. A total of 4,809 specimens belonging to six orders, 15 families and 31 species were captured during April 2009 to February 2010, using electrofishing, gillnets and traps. The family Characidae was predominant, mainly due to the abundance of freshwater species such as Astyanax ribeirae, Mimagoniates microlepis, and Hollandichthys multifasciatus. Although the estuarine regions were rarely sampled in this study, six brackish water species were captured. In this study, nine species previously unknown from JIES were discovered. Five endangered fish species, endemic to the Atlantic forest, occur at JIES, thus the presence of protected areas, as a conservation measure, is particularly relevant. © 2013 Check List and Authors.

The effects of pinning on critical currents of superconducting films

Using molecular dynamics simulations, we analyze the effects of artificial periodic arrays of pinning sites on the critical current of superconducting thin films as a function of vortex density. We analyze two types of periodic pinning array: hexagonal and Kagomé. For the Kagome pinning network we make calculations using two directions of transport current: along and perpendicular to the main axis of the lattice. Our results show that the hexagonal pinning array presents higher critical currents than the Kagomé and random pinning configuration for all vortex densities. In addition, the Kagomé networks show anisotropy in their transport properties. © 2012 Springer Science+Business Media, LLC.

Critical currents and melting temperature of a two-dimensional vortex lattice with periodic pinning

The critical current and melting temperature of a vortex system are analyzed. Calculations are made for a two-dimensional film at finite temperature with two kinds of periodic pinning: hexagonal and Kagomé. A transport current parallel and perpendicular to the main axis of the pinning arrays is applied and molecular dynamics simulations are used to calculate the vortex velocities to obtain the critical currents. The structure factor and displacements of vortices at zero transport current are used to obtain the melting temperature for both pinning arrays. The critical currents are higher for the hexagonal pinning lattice and anisotropic for both pinning arrays. This anisotropy is stronger with temperature for the hexagonal array. For the Kagomé pinning lattice, our analysis shows a multi stage phase melting; that is, as we increase the temperature, each different dynamic phase melts before reaching the melting temperature. Both the melting temperature and critical currents are larger for the hexagonal lattice, indicating the role for the interstitial vortices in decreasing the pinning strength. © 2012 Springer Science+Business Media New York.

Desarrollo de la zona costera: desarrollo y medio ambiente del Caribe en los aspectos costero y marítimo: programas y actividades posibles = Coastal area development: development and environment in the Caribbean coastal and marine aspects: possible programmes and activities

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