Spin and pseudospin symmetries in the antinucleon spectrum of nuclei

Spin and pseudospin symmetries in the spectra of nucleons and antinucleons are studied in a relativistic mean-field theory with scalar and vector Woods-Saxon potentials, in which the strength of the latter is allowed to change. We observe that, for nucleons and antinucleons, the spin symmetry is of perturbative nature and it is almost an exact symmetry in the physical region for antinucleons. The opposite situation is found in the pseudospin symmetry case, which is better realized for nucleons than for antinucleons, but is of dynamical nature and cannot be viewed in a perturbative way both for nucleons and antinucleons. This is shown by computing the spin-orbit and pseudospin-orbit couplings for selected spin and pseudospin partners in both spectra.Comment: 8 figures, uses revtex 4.1 macro

Associação da seringueira com a cultura do cacaueiro no Estado de Rondônia.

Tema Central: Sistemas Agroflorestais no Desenvolvimento Sustentável. v.2 Trabalhos voluntarios. Editores Luciano J. Montoya e Moacir J.S. Medrado

Pattern Recognition Analysis of MR Spectra

The need for multivariate analysis of magnetic resonance spectroscopy (MRS) data was recognized about 20 years ago, when it became evident that spectral patterns were characteristic of some diseases. Despite this, there is no generally accepted methodology for performing pattern recognition (PR) analysis of MRS data sets. Here, the data acquisition and processing requirements for performing successful PR as applied to human MRS studies are introduced, and the main techniques for feature selection, extraction, and classification are described. These include methods of dimensionality reduction such as principal component analysis (PCA), independent component analysis (ICA), non-negative matrix factorization (NMF), and feature selection. Supervised methods such as linear discriminant analysis (LDA), logistic regression (LogR), and nonlinear classification are discussed separately from unsupervised and semisupervised classification techniques, including k –means clustering. Methods for testing and metrics for gauging the performance of PR models (sensitivity and specificity, the ‘Confusion Matrix’, ‘k –fold cross-validation’, ‘Leave One Out’, ‘Bootstrapping’, the ‘Receiver Operating Characteristic curve’, and balanced error and accuracy rates) are briefly described. This article ends with a summary of the main lessons learned from PR applied to MRS to date

Associação da seringueira com a cultura do cafeeiro no Estado de Rondonia.

Tema Central: Sistemas Agroflorestais no Desenvolvimento Sustentavel. v.2 Trabalhos voluntarios. Editores Luciano J. Montoya e Moacir J.S. Medrado

Avaliação do comportamento de clones de seringueira (Hevea spp.) no município de Ouro Preto D'Oeste, Rondônia.

Procurou-se avaliar clones de seringueira que tenham melhor comportamento e nível de exploração comercial no município de Ouro Preto D'Oeste, Rondônia. Concluiu-se que IAN 717 foi o clone que melhor se comportou nas condições experimentais; Medições de espessura de casca e de circunferência do caule podem ser realizadas bienalmente e nao anualmente.bitstream/item/55884/1/COT2816-0001.pd

Automatic relevance source determination in human brain tumors using Bayesian NMF.

The clinical management of brain tumors is very sensitive; thus, their non-invasive characterization is often preferred. Non-negative Matrix Factorization techniques have been successfully applied in the context of neuro-oncology to extract the underlying source signals that explain different tissue tumor types, for which knowing the number of sources to calculate was always required. In the current study we estimate the number of relevant sources for a set of discrimination problems involving brain tumors and normal brain. For this, we propose to start by calculating a high number of sources using Bayesian NMF and automatically discarding the irrelevant ones during the iterative process of matrices decomposition, hence obtaining a reduced range of interpretable solutions. The real data used in this study come from a widely tested human brain tumor database. Simulated data that resembled the real data was also generated to validate the hypothesis against ground truth. The results obtained suggest that the proposed approach is able to provide a small range of meaningful solutions to the problem of source extraction in human brain tumors

Estimativa do potencial erosivo das chuvas em municípios no entorno a Flona Tapajós, Amazônia.

O objetivo deste trabalho foi estimar o potencial erosivo das chuvas em municípios no entorno da Floresta Nacional do Tapajós, no estado do Pará para avaliar anos com maior ameaça a erosão dos solos. Foram utilizados dados de precipitação pluvial disponibilizados por órgãos de monitoramento meteorológico na região. Para garantir as avaliações de uma série longa de dados fez-se o cálculo do fator (R) considerando-se o maior período (1972 a 2012) em Belterra, período intermediário (1979 a 2009) em Santarém e na série homogênea, entre 1983 a 2002. Os dados evidenciaram que nos três municípios a distribuição anual do potencial erosivo das chuvas tem comportamentos semelhantes, sendo em Rurópolis as maiores flutuações. O ano de 1995 foi o que apresentou maior erosividade das chuvas anuais, no período de maior pluviosidade com 14.328,3 MJ mm ha-1 ano -1 em Santarém, 14.620,2 MJ mm ha-1 ano -1 em Belterra e 15.251,3 MJ mm ha-1 ano -1 em Ruropolis. Chuvas anuais com menores valores foram estimados em 1992, com 5.543,4 MJ mm ha-1ano-1 (Santarém), 5.830,9 MJ mm ha-1 ano-1 (Belterra) e 7.710,5 MJ mm ha-1ano-1 (Ruroplois). Esses dados evidenciam que as áreas cultivadas com grãos ou pastagens mal manejadas mais próximas ao município de Rurópolis são mais vulneráveis à erosão hídrica em relação a Belterra e Santarém. Práticas conservacionais devem ser adotadas para manter a capacidade produtiva dos solos nessa região

Relating pseudospin and spin symmetries through charge conjugation and chiral transformations: the case of the relativistic harmonic oscillator

We solve the generalized relativistic harmonic oscillator in 1+1 dimensions, i.e., including a linear pseudoscalar potential and quadratic scalar and vector potentials which have equal or opposite signs. We consider positive and negative quadratic potentials and discuss in detail their bound-state solutions for fermions and antifermions. The main features of these bound states are the same as the ones of the generalized three-dimensional relativistic harmonic oscillator bound states. The solutions found for zero pseudoscalar potential are related to the spin and pseudospin symmetry of the Dirac equation in 3+1 dimensions. We show how the charge conjugation and $\gamma^5$ chiral transformations relate the several spectra obtained and find that for massless particles the spin and pseudospin symmetry related problems have the same spectrum, but different spinor solutions. Finally, we establish a relation of the solutions found with single-particle states of nuclei described by relativistic mean-field theories with scalar, vector and isoscalar tensor interactions and discuss the conditions in which one may have both nucleon and antinucleon bound states.Comment: 33 pages, 10 figures, uses revtex macro

Energetic potential of Sclerobium paniculatum vogel (taxi-branco) and its preferential top climatic condition in Eastern Amazonia, Brasil.

Tropentag 2009