13,031 research outputs found
A Neural Network model with Bidirectional Whitening
We present here a new model and algorithm which performs an efficient Natural
gradient descent for Multilayer Perceptrons. Natural gradient descent was
originally proposed from a point of view of information geometry, and it
performs the steepest descent updates on manifolds in a Riemannian space. In
particular, we extend an approach taken by the "Whitened neural networks"
model. We make the whitening process not only in feed-forward direction as in
the original model, but also in the back-propagation phase. Its efficacy is
shown by an application of this "Bidirectional whitened neural networks" model
to a handwritten character recognition data (MNIST data).Comment: 16page
Ocorrência da antracnose em Stylosanthes spp. no Acre e comportamento de material genético introduzido em relação ao agente causal (colletotrichum gloeosporioides).
Em 1980, uma epifitotia da antracnose do Stylosanthes, causada pelo fungo Collettottrichum gloeosporioides (penz.) Saac., foi observada em pastagens e áreas experimentais do Estado do Acre. Os sintomas caracterÃsticos da doença são descritos. Inoculação de plântulas de Stylosanthes spp. a partir de culturas puras do fungo proporcionou o aparecimento do mesmos sintomas após 15 dias. Oito gemoplasmas de duas espécies de Stylosanthes spp., S. guayanensis e S. capitata, foram avaliados no campo em duas épocas distintas. S. guayanensis mostrou-se mais suscetÃvel que S. capitata. O isolado do fungo foi também capaz de produzir sintomas em S. humilis. As condições de pastejo prevalentes parecem ter contribuÃdo para aumentar a vulnerabilidade de S. guayanensis cv. Cook à doença
Localization properties of a tight-binding electronic model on the Apollonian network
An investigation on the properties of electronic states of a tight-binding
Hamiltonian on the Apollonian network is presented. This structure, which is
defined based on the Apollonian packing problem, has been explored both as a
complex network, and as a substrate, on the top of which physical models can
defined. The Schrodinger equation of the model, which includes only nearest
neighbor interactions, is written in a matrix formulation. In the uniform case,
the resulting Hamiltonian is proportional to the adjacency matrix of the
Apollonian network. The characterization of the electronic eigenstates is based
on the properties of the spectrum, which is characterized by a very large
degeneracy. The rotation symmetry of the network and large number of
equivalent sites are reflected in all eigenstates, which are classified
according to their parity. Extended and localized states are identified by
evaluating the participation rate. Results for other two non-uniform models on
the Apollonian network are also presented. In one case, interaction is
considered to be dependent of the node degree, while in the other one, random
on-site energies are considered.Comment: 7pages, 7 figure
Independent Component analysis of the Cosmic Microwave Background
This paper presents an application of ICA to astronomical imaging. A first section describes the astrophysical context and motivates the use of source separation ideas. A second section describes our approach to the problem: the use of a noisy Gaussian stationary model. This technique uses spectral diversity and take explicitly into account contamination by additive noise. Preliminary and extremely encouraging results on realistic synthetic signals and on real data will be presented at the conferenc
Modelos de predição para peso e rendimento de cortes cárneos através de medidas no animal vivo.
Os objetivos deste trabalho foram desenvolver equações de predição com a finalidade de estimar o peso e o rendimento de cortes do traseiro de novilhos Braford através de medidas por ultrassom ?in vivo? e avaliar a inclusão das medidas de espessura de gordura na garupa e de profundidade do músculo gluteus medius e as suas relações com a acurácia dos modelos de regressão. Foram utilizados 100 novilhos com peso vivo médio de 472 Kg e 24 meses de idade. Nas 48 horas pré abate foram coletadas medidas de ultrassom da área do músculo longissimus (AOLUS); espessura de gordura subcutânea (EGSUS) no sÃtio anatômico entre a 12ª e 13ª costelas; espessura de gordura na garupa (EGP8US) e a profundidade do músculo Gluteus medius (PP8US). As equações para peso de cortes do traseiro (PCT) e para rendimento de cortes do traseiro (RCT) foram desenvolvidas através do procedimento estatÃstico de seleção de variáveis Stepwise. As caracterÃsticas AOLUS, EGSUS, EGP8US e PP8US apresentaram médias de 67,13 cm2; 3,43 mm; 6,14 mm e 86,91 mm respectivamente. Os coeficientes de correlação de Pearson entre as medidas obtidas por ultrassom e na carcaça para AUOLUS e AOLC foram de 0,89, para EGSU e EGSC de 0,92. O R2 para PCT foi de 0,71 e para RCT de 0,31 respectivamente. As variáveis EGP8US e PP8US explicam 11% da variação do rendimento dos cortes do traseiro e devem ser incorporadas no modelo
Superkicks in ultrarelativistic encounters of spinning black holes
We study ultrarelativistic encounters of two spinning, equal-mass black holes
through simulations in full numerical relativity. Two initial data sequences
are studied in detail: one that leads to scattering and one that leads to a
grazing collision and merger. In all cases, the initial black hole spins lie in
the orbital plane, a configuration that leads to the so-called "superkicks". In
astrophysical, quasicircular inspirals, such kicks can be as large as ~3,000
km/s; here, we find configurations that exceed ~15,000 km/s. We find that the
maximum recoil is to a good approximation proportional to the total amount of
energy radiated in gravitational waves, but largely independent of whether a
merger occurs or not. This shows that the mechanism predominantly responsible
for the superkick is not related to merger dynamics. Rather, a consistent
explanation is that the "bobbing" motion of the orbit causes an asymmetric
beaming of the radiation produced by the in-plane orbital motion of the binary,
and the net asymmetry is balanced by a recoil. We use our results to formulate
some conjectures on the ultimate kick achievable in any black hole encounter.Comment: 10 pages, 6 figures, 2 table
On computing real logarithms for matrices in the Lie group of special Euclidean motions in Rn
We show that the diagonal Pade approximants methods, both for computing
the principal logarithm of matrices belonging to the Lie groupSE (n, IR) of special
Euclidean motions in IRn and to compute the matrix exponential of elements in
the corresponding Lie algebra se(n, IR), are structure preserving. Also, for the
particular cases when n == 2,3 we present an alternative closed form to compute
the principal logarithm. These low dimensional Lie groups play an important
role in the kinematic motion of many mechanical systems and, for that reason,
the results presented here have immediate applications in robotic
Avaliação de dois acessos de mandioca (Manihot esculenta CRANTZ) em um sistema agroflorestal (SAFS).
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