A 300 GHz "Always-in-Focus" Focusing System for Target Detection

A focusing system for a 300 GHz radar with 5 m target distance and 10 mm diameter spot size resolution is proposed. The focusing system is based on a Gaussian telescope scheme and its main parameters have been de¬signed using Gaussian beam quasi-optical propagation theory with an in-house developed MATLAB® based analysis tool. Then, this approach has been applied to a real focusing system based on two elliptical mirrors in order to reduce the distortion and cross-polar level and a plane mirror to provide scanning capabilities. The over¬all system has been simulated with a full-wave electromag¬netic simulator and its behavior is presented. With this approach, the focusing system always works "in-focus" since the only mirror that is rotated when scanning is the output plane mirror, so the beam is almost not distorted. The design process, although based in the well-known Gaussian beam quasi-optical propagation theory, provides a fast and accurate method and minimizes the overall size of the mirrors. As a consequence, the size of the focusing system is also reduced

On the Estimation of the Surface Elevation of Regular and Irregular Waves Using the Velocity Field of Bubbles

This paper describes a new set of experiments focused on estimating time series of the free surface elevation of water (FSEW) from velocities recorded by submerged air bubbles under regular and irregular waves using a low-cost non-intrusive technique. The main purpose is to compute wave heights and periods using time series of velocities recorded at any depth. The velocities were taken from the tracking of a bubble curtain with only one high-speed digital video camera and a bubble generator. These experiments eliminate the need of intrusive instruments while the methodology can also be applied if the free surface is not visible or even if only part of the depth can be recorded. The estimation of the FSEW was successful for regular waves and reasonably accurate for irregular waves. Moreover, the algorithm to reconstruct the FSEW showed better results for larger wave amplitudes

Scaling relations for magnetic nanoparticles

A detailed investigation of the scaling relations recently proposed by [J. d'Albuquerque e Castro, D. Altbir, J. C. Retamal, and P. Vargas, Phys. Rev. Lett. 88, 237202 (2002)] to study the magnetic properties of nanoparticles is presented. Analytical expressions for the total energy of three characteristic internal configurations of the particles are obtained, in terms of which the behavior of the magnetic phase diagram for those particles upon scaling of the exchange interaction is discussed. The exponent $\eta$ in scaling relations is shown to be dependent on the geometry of the vortex core, and results for specific cases are presented.Comment: 6 pages, 4 figure

Inter-band B(E2) transition strengths in odd-mass heavy deformed nuclei

Inter-band B(E2) transition strengths between different normal parity bands in 163Dy and 165Er are described using the pseudo-SU(3) model. The Hamiltonian includes Nilsson single-particle energies, quadrupole-quadrupole and pairing interactions with fixed, parametrized strengths, and three extra rotor terms used to fine tune the energy spectra. In addition to inter-band transitions, the energy spectra and the ground state intra-band B(E2) strengths are reported. The results show the pseudo-SU(3) shell model to be a powerful microscopic theory for a description of the normal parity sector in heavy deformed odd-A nuclei.Comment: 4 figures, 2 table

Collaborative semantic web browsing with Magpie

Web browsing is often a collaborative activity. Users involved in a joint information gathering exercise will wish to share knowledge about the web pages visited and the contents found. Magpie is a suite of tools supporting the interpretation of web pages and semantically enriched web browsing. By automatically associating an ontology-based semantic layer to web resources, Magpie allows relevant services to be invoked as well as remotely triggered within a standard web browser. In this paper we describe how Magpie trigger services can provide semantic support to collaborative browsing activities

Plantas daninhas presentes na cultura do milho no estado do Rio Grande do Sul.

bitstream/item/81329/1/doc-147.pd

Evaluación briológica de los efectos de la contaminación atmosférica en la Ciudad de México

The Index of Atmospheric Purity (IAP) was used to make a preliminary evaluation of epiphytic moss response to atmospheric pollution in the urban area of Mexico City. Areal analysis indicates that there is a significant negative correlation (p < 0.5) between IAP values and SO2, NO2, NOx, Pb and temperature values of -0.45, -0.90, -0.80, -0.80, -0.90. Significant positive correlation (p < 0.05) between IAP values and O3, rainfall and relative atmospheric humidity with values of 0.70, 0.80, 0.90. Increase in atmospheric pollutants in Mexico City have promoted a gradual decrease in frequency and cover of epiphytic mosses even though some ecological factors may show the oposite effect.Se hace una evaluación preliminar de la respuesta de los musgos epífitos a la contaminación atmosférica usando el Indice de Pureza Atmosférica (IPA) en el área urbana de la Ciudad de México. El análisis por zonas indica que hay una relación inversa y significativa (p < 0.5) entre el IPA y SO2, NO2, NOx, Pb y la temperatura con valores de -0.45, -0.90, -0.80, -0.80, -0.90. También se encontró una relación directa y significativa (p < 0.05) entre el IPA y el O3, la precipitación pluvial y la humedad relativa con valores de 0.70, 0.80, 0.90. Los incrementos en los niveles de algunos contaminantes atmosféricos en la Ciudad de México han promovido la disminución gradual en la frecuencia de aparición y cobertura de musgos epífitos, aunque algunas variables ambientales pueden tener el efecto opuesto

Diverse routes to oscillation death in a coupled-oscillator system.

We study oscillation death (OD) in a well-known coupled-oscillator system that has been used to model cardiovascular phenomena. We derive exact analytic conditions that allow the prediction of OD through the two known bifurcation routes, in the same model, and for different numbers of coupled oscillators. Our exact analytic results enable us to generalize OD as a multiparameter-sensitive phenomenon. It can be induced, not only by changes in couplings, but also by changes in the oscillator frequencies or amplitudes. We observe synchronization transitions as a function of coupling and confirm the robustness of the phenomena in the presence of noise. Numerical and analogue simulations are in good agreement with the theory

Marrying research evidence and policies in Latin America and the Caribbean: The Case of Violence

Violence is probably the most important public health problem in Latin America and the Caribbean. Despite the efforts to attach that problem, research and policies do not feedback each other in an apropiate way. There is need for develop implementation research in the region in order to reduce that gap.Fil: Ardila Gómez, Sara Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Lanus. Departamento de Salud Comunitaria; Argentina. Universidad de Buenos Aires. Facultad de Psicología. Área de Salud Pública y Salud Mental; ArgentinaFil: Lugo Palacios, D.. London School Of Hygiene And Tropical Medicine; Reino UnidoFil: Vargas Palacios, E.. No especifíca