1,627 research outputs found
Gaussian-type lower bounds for the density of solutions of SDEs driven by fractional Brownian motions
In this paper we obtain Gaussian-type lower bounds for the density of
solutions to stochastic differential equations (SDEs) driven by a fractional
Brownian motion with Hurst parameter . In the one-dimensional case with
additive noise, our study encompasses all parameters , while the
multidimensional case is restricted to the case . We rely on a mix of
pathwise methods for stochastic differential equations and stochastic analysis
tools.Comment: Published at http://dx.doi.org/10.1214/14-AOP977 in the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Dipole-dipole dispersion interactions between neutrons
We investigate the long-range interactions between two neutrons utilizing
recent data on the neutron static and dynamic electric and magnetic dipole
polarizabilities. The resulting long-range potentials are used to make
quantitative comparisons between the collisions of a neutron with a neutron and
a neutron with a proton. We also assess the importance of the first pion
production threshold and first excited state of the nucleon, the
-resonance ( = + 3/2, I = 3/2). We found both dynamical
effects to be quite relevant for distances r between ~ 50 fm up to ~ fm
in the nn system, the neutron-wall system and in the wall-neutron-wall system,
reaching the expected asymptotic limit beyond that. Relevance of our findings
to the confinement of ultra cold neutrons inside bottles is discussed.Comment: 11 pages, 12 figures, Version to be published in the European
Physical Journal A (2017
Dog Breed Classification Using Convolutional Neural Networks: Interpreted Through a Lockean Perspective
The problem of fine-grained classification is one in which traditionally humans have fared better than computers. Only recently, with the advent of complex Machine Learning techniques, we have seen systems that can compete with or beat humans at this problem. In this work, we trained two Convolutional Neural Networks (CNNs) on the Stanford Dogs dataset and made them recognize dog breeds. We also analyzed the response maps of the CNNs with the aim of determining which breed-specific features the networks had learned in order to classify the images. Upon obtaining these features, we attempted to gain an insight into them for comparison with the human understanding of breeds under a Lockean interpretation
Outras espécies florestais.
Acácia-negra; Evolução da cultura; Pesquisa com acácia-negra no Brasil; Seringueira; Evoluação da cultura; Pesquisa com seringueira no Brasil; Teca; Evolução da cultura; Pesquisa com teca no Brasil
NMR Determination of an Incommensurate Helical Antiferromagnetic Structure in EuCo2As2
We report Eu, As and Co nuclear magnetic resonance
(NMR) results on EuCoAs single crystal. Observations of Eu and
As NMR spectra in zero magnetic field at 4.3 K below an
antiferromagnetic (AFM) ordering temperature = 45 K and its
external magnetic field dependence clearly evidence an incommensurate helical
AFM structure in EuCoAs. Furthermore, based on Co NMR data in
both the paramagnetic and the incommensurate AFM states, we have determined the
model-independent value of the AFM propagation vector = (0, 0, 0.73
0.07)2/ where is the lattice parameter. Thus the
incommensurate helical AFM state was characterized by only NMR data with
model-independent analyses, showing NMR to be a unique tool for determination
of the spin structure in incommensurate helical AFMs.Comment: 6 pages, 4 figures, accepted for publication in Phys.Rev.
The structure of the space of affine Kaehler curvature tensors as a complex module
We use results of Matzeu and Nikcevic to decompose the space of affine
Kaehler curvature tensors as a direct sum of irreducible modules in the complex
settin
Scalar form factors and nuclear interactions
The scalar-isoscalar term in the two-pion exchange potential is
abnormally large and does not respect the hierarchy of effects predicted by
chiral perturbation theory. We argue that this anomaly is associated with
non-perturbative effects, which are also present in the scalar form
factor.Comment: Talk given at the 20EFB, Pisa, Italy, September 2007. 3 pages and 4
figure
Exploring universality in nuclear clusters with Halo EFT
I present results and highlight aspects of halo EFT to loosely bound systems
composed of nucleons and alpha particles, with emphasis on Coulomb
interactions.Comment: 3 pages, 2 figures, talk given at the 21th European Conference on
Few-Body Problems in Physics, Salamanca, Aug. 29th - Sep. 3rd, 201
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