Non-parametric comparison of histogrammed two-dimensional data distributions using the Energy Test

When monitoring complex experiments, comparison is often made between regularly acquired histograms of data and reference histograms which represent the ideal state of the equipment. With the larger HEP experiments now ramping up, there is a need for automation of this task since the volume of comparisons could overwhelm human operators. However, the two-dimensional histogram comparison tools available in ROOT have been noted in the past to exhibit shortcomings. We discuss a newer comparison test for two-dimensional histograms, based on the Energy Test of Aslan and Zech, which provides more conclusive discrimination between histograms of data coming from different distributions than methods provided in a recent ROOT release.The Science and Technology Facilities Council, U

Phenomenological study of the electronic transport coefficients of graphene

Using a semi-classical approach and input from experiments on the conductivity of graphene, we determine the electronic density dependence of the electronic transport coefficients -- conductivity, thermal conductivity and thermopower -- of doped graphene. Also the electronic density dependence of the optical conductivity is obtained. Finally we show that the classical Hall effect (low field) in graphene has the same form as for the independent electron case, characterized by a parabolic dispersion, as long as the relaxation time is proportional to the momentum.Comment: 4 pages, 1 figur

Tests of Bayesian Model Selection Techniques for Gravitational Wave Astronomy

The analysis of gravitational wave data involves many model selection problems. The most important example is the detection problem of selecting between the data being consistent with instrument noise alone, or instrument noise and a gravitational wave signal. The analysis of data from ground based gravitational wave detectors is mostly conducted using classical statistics, and methods such as the Neyman-Pearson criteria are used for model selection. Future space based detectors, such as the \emph{Laser Interferometer Space Antenna} (LISA), are expected to produced rich data streams containing the signals from many millions of sources. Determining the number of sources that are resolvable, and the most appropriate description of each source poses a challenging model selection problem that may best be addressed in a Bayesian framework. An important class of LISA sources are the millions of low-mass binary systems within our own galaxy, tens of thousands of which will be detectable. Not only are the number of sources unknown, but so are the number of parameters required to model the waveforms. For example, a significant subset of the resolvable galactic binaries will exhibit orbital frequency evolution, while a smaller number will have measurable eccentricity. In the Bayesian approach to model selection one needs to compute the Bayes factor between competing models. Here we explore various methods for computing Bayes factors in the context of determining which galactic binaries have measurable frequency evolution. The methods explored include a Reverse Jump Markov Chain Monte Carlo (RJMCMC) algorithm, Savage-Dickie density ratios, the Schwarz-Bayes Information Criterion (BIC), and the Laplace approximation to the model evidence. We find good agreement between all of the approaches.Comment: 11 pages, 6 figure

Rendimento de derruba e extração mecanizada em florestas de terra firme da Amazônia.

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Disorder Induced Localized States in Graphene

We consider the electronic structure near vacancies in the half-filled honeycomb lattice. It is shown that vacancies induce the formation of localized states. When particle-hole symmetry is broken, localized states become resonances close to the Fermi level. We also study the problem of a finite density of vacancies, obtaining the electronic density of states, and discussing the issue of electronic localization in these systems. Our results also have relevance for the problem of disorder in d-wave superconductors.Comment: Replaced with published version. 4 pages, 4 figures. Fig. 1 was revise

Localized states at zigzag edges of bilayer graphene

We report the existence of zero energy surface states localized at zigzag edges of bilayer graphene. Working within the tight-binding approximation we derive the analytic solution for the wavefunctions of these peculiar surface states. It is shown that zero energy edge states in bilayer graphene can be divided into two families: (i) states living only on a single plane, equivalent to surface states in monolayer graphene; (ii) states with finite amplitude over the two layers, with an enhanced penetration into the bulk. The bulk and surface (edge) electronic structure of bilayer graphene nanoribbons is also studied, both in the absence and in the presence of a bias voltage between planes.Comment: 4 pages, 5 figure

Capim-Tanzânia: irrigação e adubação nitrogenada.

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Irrigação e adubação nitrogenada em gramíneas forrageiras.

O objetivo deste trabalho foi avaliar o efeito de diferentes níveis de irrigação e de adubação nitrogenada sobre a produtividade média de matéria seca (MS) e o teor de proteína bruta (PB) de três gramíneas forrageiras. O trabalho foi conduzido na área experimental da Embrapa Meio-Norte em Parnaíba-PI, em Neossolo Quartzarênico Órtico Típico. As gramíneas utilizadas foram Pennisetum purpureum, cv. Pioneiro; Panicum maximum, cv. Tanzânia e Cynodon spp., cv. Tifton-85. Os níveis de irrigação aplicados foram calculados em função do fracionamento da evaporação do tanque Classe A (ECA) entre duas irrigações consecutivas: 0,2; 0,6 e 1,0. Os tratamentos de adubação foram 100, 200 e 300 kg/ha de N aplicados na forma de uréia e em cobertura. Para efeito de análise foram processados cinco cortes das gramíneas no período de avaliação. A produtividade de matéria seca (MS) da cultivar Tanzânia (24.984 kg/ha) é significativamente superior às MS das cultivares Tifton-85 (18.231 kg/ha) e Pioneiro (16.239 kg/ha). A combinação do nível de água correspondente a 0,2 ECA com o nível de adubação de 200 kg/ha de N apresenta os melhores resultados. O efeito de N sobre PB é linear e significativo (P<0,05) e o teor médio de PB da cultivar Pioneiro (15,58 %) é superior aos das cultivares Tanzânia (12,82 %) e Tifton-85 (12,85).bitstream/item/126432/1/boletim-42-Irrigacao-e-adubacao-nitrogenada-em-gramineas-forrageiras.pd