6,116 research outputs found
Consistent deformations of [p,p]-type gauge field theories
Using BRST-cohomological techniques, we analyze the consistent deformations
of theories describing free tensor gauge fields whose symmetries are
represented by Young tableaux made of two columns of equal length p, p>1. Under
the assumptions of locality and Poincare invariance, we find that there is no
consistent deformation of these theories that non-trivially modifies the gauge
algebra and/or the gauge transformations. Adding the requirement that the
deformation contains no more than two derivatives, the only possible
deformation is a cosmological-constant-like term.Comment: 17 pages, details of a proof added, accepted for publication in JHE
Siscero - Sistema de clipping da Embrapa Rondônia.
O Siscero, ou Sistema de clipping da Embrapa Rondônia, é uma aplicação desenvolvida em plataforma web para o registro de matérias jornalísticas ou outras inserções na mídia que envolvam a Embrapa Rondônia. As informações são armazenadas em banco de dados relacional e o sistema permite o registro de arquivos digitais, como imagem, PDF, áudio ou vídeo. Uma interface de pesquisa oferece uma série de filtros para busca de registros e gráficos interativos permitem avaliar, comparar e monitorar o desempenho da Empresa na mídia. Este documento contextualiza o clipping no universo corporativo, faz uma retrospectiva das iniciativas passadas e da situação atual do clipping realizado pela Embrapa e apresenta o Siscero como uma ferramenta estratégica. Um manual para utilização do sistema e um guia de instalação também fazem parte do conteúdo.bitstream/item/35944/1/doc137-siscero.pd
Risk Assessment for Glaucoma
Glaucoma is undergoing a paradigm shift and transitioning from merely disease staging to evidence-based risk assessment of in the individual patient
Polarization-selective excitation of N-V centers in diamond
The nitrogen-vacancy (N-V) center in diamond is promising as an electron spin
qubit due to its long-lived coherence and optical addressability. The ground
state is a spin triplet with two levels () degenerate at zero
magnetic field. Polarization-selective microwave excitation is an attractive
method to address the spin transitions independently, since this allows
operation down to zero magnetic field. Using a resonator designed to produce
circularly polarized microwaves, we have investigated the polarization
selection rules of the N-V center. We first apply this technique to N-V
ensembles in [100] and [111]-oriented samples. Next, we demonstrate an imaging
technique, based on optical polarization dependence, that allows rapid
identification of the orientations of many single N-V centers. Finally, we test
the microwave polarization selection rules of individual N-V centers of known
orientation
Comportamento produtivo de caprinos anglo-nubiano no estado do Piaui.
bitstream/item/97227/1/PAND320001.pd
Estimating the Risk of Developing Glaucoma
The issue of risk assessment in glaucoma has received increasing attention in the past few years since the publication of results from the Ocular Hypertension Treatment Study. Predictive models have been developed in order to estimate the risk that patients with ocular hypertension will develop glaucoma if left untreated. The purpose of this article is to review issues on the development and validation of predictive models to estimate risk of glaucoma development. Current models are reviewed and details about their development and validation are provided
An Unusual Antagonistic Pleiotropy in the Penna Model for Biological Ageing
We combine the Penna Model for biological aging, which is based on the
mutation-accumulation theory, with a sort of antagonistic pleiotropy. We show
that depending on how the pleiotropy is introduced, it is possible to reproduce
both the humans mortality, which increases exponentially with age, and fruitfly
mortality, which decelerates at old ages, allowing the appearance of
arbitrarily old Methuselah's.Comment: 8 pages, 3 figures, to appear in Physica
Structural Change Can Be Detected in Advanced-Glaucoma Eyes.
PurposeTo compare spectral-domain optical coherence tomography (SD-OCT) standard structural measures and a new three-dimensional (3D) volume optic nerve head (ONH) change detection method for detecting change over time in severely advanced-glaucoma (open-angle glaucoma [OAG]) patients.MethodsThirty-five eyes of 35 patients with very advanced glaucoma (defined as a visual field mean deviation < -21 dB) and 46 eyes of 30 healthy subjects to estimate aging changes were included. Circumpapillary retinal fiber layer thickness (cpRNFL), minimum rim width (MRW), and macular retinal ganglion cell-inner plexiform layer (GCIPL) thicknesses were measured using the San Diego Automated Layer Segmentation Algorithm (SALSA). Progression was defined as structural loss faster than 95th percentile of healthy eyes. Three-dimensional volume ONH change was estimated using the Bayesian-kernel detection scheme (BKDS), which does not require extensive retinal layer segmentation.ResultsThe number of progressing glaucoma eyes identified was highest for 3D volume BKDS (13, 37%), followed by GCPIL (11, 31%), cpRNFL (4, 11%), and MRW (2, 6%). In advanced-OAG eyes, only the mean rate of GCIPL change reached statistical significance, -0.18 μm/y (P = 0.02); the mean rates of cpRNFL and MRW change were not statistically different from zero. In healthy eyes, the mean rates of cpRNFL, MRW, and GCIPL change were significantly different from zero. (all P < 0.001).ConclusionsGanglion cell-inner plexiform layer and 3D volume BKDS show promise for identifying change in severely advanced glaucoma. These results suggest that structural change can be detected in very advanced disease. Longer follow-up is needed to determine whether changes identified are false positives or true progression
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