6,412 research outputs found
Characterizing neuromorphologic alterations with additive shape functionals
The complexity of a neuronal cell shape is known to be related to its
function. Specifically, among other indicators, a decreased complexity in the
dendritic trees of cortical pyramidal neurons has been associated with mental
retardation. In this paper we develop a procedure to address the
characterization of morphological changes induced in cultured neurons by
over-expressing a gene involved in mental retardation. Measures associated with
the multiscale connectivity, an additive image functional, are found to give a
reasonable separation criterion between two categories of cells. One category
consists of a control group and two transfected groups of neurons, and the
other, a class of cat ganglionary cells. The reported framework also identified
a trend towards lower complexity in one of the transfected groups. Such results
establish the suggested measures as an effective descriptors of cell shape
Opinion and community formation in coevolving networks
In human societies opinion formation is mediated by social interactions,
consequently taking place on a network of relationships and at the same time
influencing the structure of the network and its evolution. To investigate this
coevolution of opinions and social interaction structure we develop a dynamic
agent-based network model, by taking into account short range interactions like
discussions between individuals, long range interactions like a sense for
overall mood modulated by the attitudes of individuals, and external field
corresponding to outside influence. Moreover, individual biases can be
naturally taken into account. In addition the model includes the opinion
dependent link-rewiring scheme to describe network topology coevolution with a
slower time scale than that of the opinion formation. With this model
comprehensive numerical simulations and mean field calculations have been
carried out and they show the importance of the separation between fast and
slow time scales resulting in the network to organize as well-connected small
communities of agents with the same opinion.Comment: 10 pages, 5 figures. New inset for Fig. 1 and references added.
Submitted to Physical Review
Status of the HIE-ISOLDE project at CERN
The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear
facility with a mandate to significantly improve the quality and increase the
intensity and energy of radioactive nuclear beams produced at CERN. The project
will expand the experimental nuclear physics programme at ISOLDE by focusing on
an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a
40 MV superconducting linac comprising thirty-two niobium-on-copper
sputter-coated quarter-wave resonators housed in six cryomodules. The new linac
will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u.
The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using
two high- cryomodules placed downstream of REX, before the energy
variable section of the existing linac is replaced with two low-
cryomodules and two additional high- cryomodules are installed to attain
over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the
project including a status summary of the different R&D activities and the
schedule will outlined.Comment: 7 pages, 12 figures, submitted to the Heavy Ion Accelerator
Technology conference (HIAT) 2012, in Chicag
Hyperfine magnetic field in ferromagnetic graphite
Information on atomic-scale features is required for a better understanding
of the mechanisms leading to magnetism in non-metallic, carbon-based materials.
This work reports a direct evaluation of the hyperfine magnetic field produced
at 13C nuclei in ferromagnetic graphite by nuclear magnetic resonance (NMR).
The experimental investigation was made possible by the results of
first-principles calculations carried out in model systems, including graphene
sheets with atomic vacancies and graphite nanoribbons with edge sites partially
passivated by oxygen. A similar range of maximum hyperfine magnetic field
values (18-21T) was found for all systems, setting the frequency span to be
investigated in the NMR experiments; accordingly, a significant 13C NMR signal
was detected close to this range without any external applied magnetic field in
ferromagnetic graphite
Avaliação de classificadores automáticos no mapeamento de áreas cafeeiras da Região de Guaxupé, Minas Gerais.
O mapeamento da ocupação da terra constitui uma das mais importantes atividades de geração de dados para gerenciamento e monitoramento de ambientes agrícolas. Pretendeu-se neste trabalho avaliar a exatidão da interpretação visual de uma imagem SPOT 5 no mapeamento do café na região de Guaxupé, tendo como referência dados obtidos em campo, bem como comparar o desempenho de técnicas de mapeamento automático da mesma área em comparação com a interpretação visual,visando a avaliação da viabilidade de aplicação destas técnicas para agilizar o mapeamento do parque cafeeiro na região.Foram trabalhadas imagens SPOT 5 com resolução espacial de 10 metros e de 2,5 metros. A cena foi submetida ao processamento por diferentes métodos de classificação automática para a imagem com resolução de 10 metros e por interpretação visual para a imagem com resolução de 2,5 metros. Dados obtidos em campo foram tomados como referência para obtenção de índices de exatidão do mapeamento. Foram estratificadas as classes café, mata e outros usos, sendo esta última oriunda do agrupamento dos demais tipos de vegetação como culturas anuais, pastagens, solo exposto, áreas urbanas, etc. Os índices utilizados foram calculados de maneira a permitir a avaliação da exatidão global da classificação e também individualmente para a classe café
Volatilização de amônia de fontes nitrogenadas em feijoeiro irrigado no sistema plantio direto.
O objetivo deste estudo foi avaliar as perdas de N por volatilização de NH3, em diferentes fontes de nitrogênio aplicadas no feijoeiro comum irrigado, cultivado em Latossolo de Cerrado sobre palhada de braquiária em sistema plantio direto.Conpeex 2010
Volatilização de amônia de adubos nitrogenados aplicados no feijoeiro irrigado cultivado no sistema plantio direto.
Este trabalho teve como objetivo avaliar as perdas de N por volatilização de NH3, com a aplicação de diferentes fontes nitrogenadas no feijoeiro cultivado em sistema plantio direto no inverno
Variáveis e modelos para estimativa da produtividade do cafeeiro a partir de índices de vegetação derivados de imagens Landsat.
Abstract. Coffee fields present a specific pattern of productivity resulting in high and low production in alternated years. Branches grown the first phenological year will produce coffee beans the second phenological year. In high-production years a plant works mostly to grain-filling to the detriment of new branches which will be responsible for production the following year. In low-production years the plant works rather to grow new branches which will produce beans the subsequent year. This feature can be related to the foliar biomass, which can be estimated through remote sensing derived vegetation indices. Several studies report this feature must be incorporated in modeling coffee yield coupled with agrometeorogical models. In this paper we derived Landsat vegetation indices related to coffee plots in order to obtain relationships to yield of the same coffee plots. Biophisical variables and yield data were colected in interviews with farmers from four locations in the whole largest Brazilian coffee-exporting province. Vegetation indices and biophysical variables were selected through stepwise regression in order to obtain the best regression models to estimate coffee yield. Outcomes showed that general models and specific models obtained for Mundo Novo variety presented Pearson's correlation coeficients (r) from 0,64 to 0,71 while models for Catuaí variety showed better results (r = 0,85). Although coffee yield cannot be estimated exclusively from these models, they can be usefull coupled with agrometeorogical models for estimating coffee yield
Avaliação preliminar da interação bactéria/filmes derivados de quitosana por microscopia de força atômica.
Development of zein-based edible coating containing essential oil aiming extending papaya (Carica papaya L.) shelf life.
Zeins are hydrophobic proteins that can be extracted from maize grains or from corn gluten meal (CGM), which is a by-product of ethanol and starch production
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