Um algoritmo para contorno automático de dados geológicos

It is presented an algorithm for automatic contouring of geological data and geographical reference data. This algorithm was derived from on already published in Basic language, rewritten in TURBO PASCAL language, and adapted to perform continuous plotting of contour curves. This paper presents a revision of current methods for automatic contouring of regular grids and describes the algorithms for storing, sorting, and tracking the intersection segments which allow the continuous plotting. These algorithms, with some modifications, could be used to perform automatic pattern recognition in maps (for example, geological boundaries and drainage networks).Este trabalho apresenta um algoritmo para contorno automático de dados geológicos, bem como de quaisquer outros referenciados geograficamente. Esse algoritmo foi baseado num outro escrito em linguagem Basic, reescrito em linguagem Turbo Pascal e adaptado para permitir a plotagem contínua das curvas de isovalores. É também apresentada uma revisão dos métodos correntes para contorno automático de malhas regulares e uma descrição dos algoritmos para armazenamento, classificação e rastreamento das intersecções das curvas, os quais permitem a plotagem contínua das mesmas. Esses algoritmos, com algumas modificações, poderiam ser utilizados para se fazer o reconhecimento automático de padrões em mapas, tais como contatos geológicos e redes de drenagens

GEOPLOT: um sistema gráfico para representações de modelos digitais de terrenos

This paper presents a graphics system, designated GEOPLOT, developed to display digital terrain models graphically. GEOPLOT is a set of TURBO PASCAL programs for IBM-PC compatible microcomputers. These programs allow one to obtain a map of a data points, the convex hull of a set of data points, and the interpolation of a the digital model and its graphical displays (i.e. contour map and perspective plot). This system also contains a computer program that retrieves the plotting files from display programs and puts out high quality drawings directly on standart dot printers. Finally GEPLOT graphics system provides graphlcal dlsplays of digital terrain models rapidly, with accuracy and versatility.Este trabalho apresenta um sistema gráfico, denominado GEOPLOT, desenvolvido para obter representações gráficas espaciais de modelos digitais de terrenos. GEOPLOT é um conjunto de programas escritos em linguagenm TURBO-PASCAL, para microcomputadores nacionais compatíveis ao IBM-PC. Estes programas permitem obter o mapa de localização de pontos, a fronteira convexa de um conjunto de pontos de dados, a interpolação do modelo digital do terreno e suas representações gráficas (i.e., mapa de contorno e o bloco-diagrama). Foi desenvolvido também um programa que permite gerar as saídas gráficas dos programas do GEOPLOT diretamente na impressora matricial de pontos. Finalmente, o sistema gráfico GEOPLOT proporciona representações gráficas de modelos digitais de terrenos com rapidez, precisão e versatilidade

Modelling of Optical Detection of Spin-Polarized Carrier Injection into Light-Emitting Devices

We investigate the emission of multimodal polarized light from Light Emitting Devices due to spin-aligned carriers injection. The results are derived through operator Langevin equations, which include thermal and carrier-injection fluctuations, as well as non-radiative recombination and electronic g-factor temperature dependence. We study the dynamics of the optoelectronic processes and show how the temperature-dependent g-factor and magnetic field affect the polarization degree of the emitted light. In addition, at high temperatures, thermal fluctuation reduces the efficiency of the optoelectronic detection method for measuring spin-polarization degree of carrier injection into non-magnetic semicondutors.Comment: 15 pages, 7 figures, replaced by revised version. To appear in Phys. Rev.

Light Lambda-Lambda Hypernuclei and the Onset of Stability for Lambda-Xi Hypernuclei

New Faddeev-Yakubovsky calculations for light Lambda-Lambda hypernuclei are presented in order to assess the self consistency of the Lambda-Lambda hypernuclear binding-energy world data and the implied strength of the Lambda-Lambda interaction, in the wake of recent experimental reports on Lambda-Lambda-4H and Lambda-Lambda-6He. Using Gaussian soft-core simulations of Nijmegen one-boson-exchange model interactions, the Nijmegen soft-core model NSC97 simulations are found close to reproducing the recently reported binding energy of Lambda-Lambda-6He, but not those of other species. For stranger systems, Faddeev calculations of light Lambda-Xi hypernuclei, using a simulation of the strongly attractive Lambda-Xi interactions due to the same model, suggest that Lambda-Xi-6He marks the onset of nuclear stability for Xi hyperons.Comment: 5 pages, 3 postscript figures; fig.2 replaced, minor changes, accepted as Rapid Communication in PR

Ionic liquid extraction unveils previously occluded humic-bound iron in peat soil pore water

Globally, peatland ecosystems store tremendous amounts of C relative to their extent on the landscape, largely owing to saturated soils which limit decomposition. While there is still considerable uncertainty regarding CO2 production potential below the water table in peatland ecosystems, extracellular Fe reduction has been suggested as a dominant pathway for anaerobic metabolism. However, colorimetric methods commonly used to quantitate Fe and partition between redox species are known to be unreliable in the presence of complex humic substances, which are common in peatland pore water. We evaluated both the standard o-phenanthroline (o-P) Method and an ionic liquid extraction (ILE) Method followed by quantitation with inductively coupled plasma optical emission spectrometry (ICP–OES) to compare total Fe recovery and Fe2+/Fe3+ ratios in four distinct peatland ecosystems, ranging from rich fen to bog. While total Fe concentrations measured with ILE and o-P were correlated, the ILE method proved to be superior in both total Fe quantitation and in separately quantifying ferric (Fe3+) and ferrous (Fe2+) iron. In peat pore water, the o-P Method underestimated Fe3+ by as much as 100%. A multivariate approach utilizing fluorescence- and ultraviolet (UV)–visable (Vis) spectroscopy identified indices of dissolved organic matter (DOM) humification and redox status that correlated with poor performance of the o-P Method in peat pore water. Where these interferences are present, we suggest that site-specific empirical correction factors for quantitation of total Fe by o-P can be created from ILE of Fe, but recommend ILE for accurate appraisals of iron speciation and redox processes

Measurement of the Xi-p Scattering Cross Sections at Low Energy

In this paper we report cross-section measurements for $\Xi^-p$ elastic and inelastic scatterings at low energy using a scintillating fiber active target. Upper limit on the total cross-section for the elastic scattering was found to be 24 mb at 90% confidence level, and the total cross section for the $\Xi^-p\to\Lambda\Lambda$ reaction was found to be $4.3^{+6.3}_{-2.7}$ mb. We compare the results with currently competing theoretical estimates.Comment: 9 page

A Unified Algebraic Approach to Few and Many-Body Correlated Systems

The present article is an extended version of the paper {\it Phys. Rev.} {\bf B 59}, R2490 (1999), where, we have established the equivalence of the Calogero-Sutherland model to decoupled oscillators. Here, we first employ the same approach for finding the eigenstates of a large class of Hamiltonians, dealing with correlated systems. A number of few and many-body interacting models are studied and the relationship between their respective Hilbert spaces, with that of oscillators, is found. This connection is then used to obtain the spectrum generating algebras for these systems and make an algebraic statement about correlated systems. The procedure to generate new solvable interacting models is outlined. We then point out the inadequacies of the present technique and make use of a novel method for solving linear differential equations to diagonalize the Sutherland model and establish a precise connection between this correlated system's wave functions, with those of the free particles on a circle. In the process, we obtain a new expression for the Jack polynomials. In two dimensions, we analyze the Hamiltonian having Laughlin wave function as the ground-state and point out the natural emergence of the underlying linear $W_{1+\infty}$ symmetry in this approach.Comment: 18 pages, Revtex format, To appear in Physical Review

Quantum theory of the far-off-resonance continuous-wave Raman laser: Heisenberg-Langevin approach

We present the quantum theory of the far-off-resonance continuous-wave Raman laser using the Heisenberg-Langevin approach. We show that the simplified quantum Langevin equations for this system are mathematically identical to those of the nondegenerate optical parametric oscillator in the time domain with the following associations: pump pump, Stokes signal, and Raman coherence idler. We derive analytical results for both the steady-state behavior and the time-dependent noise spectra, using standard linearization procedures. In the semiclassical limit, these results match with previous purely semiclassical treatments, which yield excellent agreement with experimental observations. The analytical time-dependent results predict perfect photon statistics conversion from the pump to the Stokes and nonclassical behavior under certain operational conditions