5,395 research outputs found
Equality of opportunity and educational achievement in Portugal
Portugal has one of the highest levels of income inequality in Europe, and low wages and unemployment are concentrated among low skill individuals. Education is an important determinant of inequality. However, there are large differences in the educational attainment of different individuals in the population, and the sources of these differences emerge early in the life-cycle when families play a central role in individual development. We estimate that most of the variance of school achievement at age 15 is explained by family characteristics. Observed school inputs explain very little of adolescent performance. Children from highly educated parents benefit of rich cultural environments in the home and become highly educated adults. Education policy needs to be innovative: (1) it needs to explicitly recognize the fundamental long run role of families on child development; (2) it needs to acknowledge the failure of traditional input based policies
Non-singular inflation with vacuum decay
On the basis of a semi-classical analysis of vacuum energy in an expanding
spacetime, we describe a non-singular cosmological model in which the vacuum
density decays with time, with a concomitant production of matter. During an
infinitely long period we have an empty, inflationary universe, with H \approx
1. This primordial era ends in a fast phase transition, during which H and
\Lambda decrease to nearly zero in a few Planck times, with release of a huge
amount of radiation. The late-time scenario is similar to the standard model,
with the radiation phase followed by a long dust era, which tends
asymptotically to a de Sitter universe, with vacuum dominating again. An
analysis of the redshift-distance relation for supernovas Ia leads to
cosmological parameters in agreement with other current estimations.Comment: Work presented at IRGAC 2006, Barcelona, July 11-15 2006. To appear
in a special issue of Journal of Physics
Deep Multi-instance Networks with Sparse Label Assignment for Whole Mammogram Classification
Mammogram classification is directly related to computer-aided diagnosis of
breast cancer. Traditional methods rely on regions of interest (ROIs) which
require great efforts to annotate. Inspired by the success of using deep
convolutional features for natural image analysis and multi-instance learning
(MIL) for labeling a set of instances/patches, we propose end-to-end trained
deep multi-instance networks for mass classification based on whole mammogram
without the aforementioned ROIs. We explore three different schemes to
construct deep multi-instance networks for whole mammogram classification.
Experimental results on the INbreast dataset demonstrate the robustness of
proposed networks compared to previous work using segmentation and detection
annotations.Comment: MICCAI 2017 Camera Read
Evolution of density perturbations in decaying vacuum cosmology: The case of non-zero perturbations in the cosmological term
We extend the results of a previous paper where a model of interacting dark
energy, with a cosmological term decaying linearly with the Hubble parameter,
is tested against the observed mass power spectrum. In spite of the agreement
with observations of type Ia supernovas, baryonic acoustic oscillations and the
cosmic microwave background, we had shown previously that no good concordance
is achieved if we include the mass power spectrum. However, our analysis was
based on the ad hoc assumption that the interacting cosmological term is
strictly homogeneous. Now we perform a more complete analysis, by perturbing
such a term. Although our conclusions are still based on a particular, scale
invariant choice of the primordial spectrum of dark energy perturbations, we
show that a cosmological term decaying linearly with the Hubble parameter is
indeed disfavored as compared to the standard model.Comment: Version accepted for publication in Physical Review
Vortex-line liquid phases: Longitudinal superconductivity in the lattice London model
We study the vortex-line lattice and liquid phases of a clean type-II
superconductor by means of Monte Carlo simulations of the lattice London model.
Motivated by a recent controversy regarding the presence, within this model, of
a vortex-liquid regime with longitudinal superconducting coherence over long
length scales, we directly compare two different ways to calculate the
longitudinal coherence. For an isotropic superconductor, we interpret our
results in terms of a temperature regime within the liquid phase in which
longitudinal superconducting coherence extends over length scales larger than
the system thickness studied. We note that this regime disappears in the
moderately anisotropic case due to a proliferation, close to the flux-line
lattice melting temperature, of vortex loops between the layers.Comment: 8 pages, Revtex, with eps figures. To appear in Phys. Rev.
Evidence of Two Distinct Dynamic Critical Exponents in Connection with Vortex Physics
The dynamic critical exponent is determined from numerical simulations
for the three-dimensional (3D) lattice Coulomb gas (LCG) and the 3D XY models
with relaxational dynamics. It is suggested that the dynamics is characterized
by two distinct dynamic critical indices and related to the
divergence of the relaxation time by and
, where is the correlation length and the
wavevector. The values determined are and for the
3D LCG and and for the 3D XY model. It is argued
that the nonlinear exponent relates to , whereas the usual
Hohenberg-Halperin classification relates to . Possible implications for the
interpretation of experiments are pointed out. Comparisons with other existing
results are discussed.Comment: to appear in PR
Desenvolvimento do agroturismo em Cachoeiras de Macacu, RJ: subsĂdios ao planejamento da atividade agroturĂstica associada Ă produção agropecuĂĄria de base familiar.
O MunicĂpio de Cachoeiras de Macacu estĂĄ situado numa regiĂŁo que exibe grande riqueza de atributos naturais, apresentando vocação para a exploração de atividades turĂsticas de cunho rural e ecolĂłgico, e ainda, por desenvolver agropecuĂĄria expressiva, apresenta potencial para explorar o segmento do turismo associado Ă s atividades produtivas do meio rural (agricultura, pecuĂĄria e silvicultura), o agroturismo. Entretanto, para que a atividade seja sustentĂĄvel, requer planejamento, sendo necessĂĄrio um estudo prĂ©vio de viabilidade, que considere aspectos fĂsicos, sociais, culturais, econĂŽmicos e ambientais. Face a isso, este estudo teve por objetivo fazer um levantamento diagnĂłstico sobre as potencialidades e limitaçÔes do MunicĂpio de Cachoeiras de Macacu em relação ao agroturismo; e com base nisso, elaborar um plano preliminar para subsidiar o desenvolvimento da atividade. Para tanto, foram compilados dados secundĂĄrios e primĂĄrios. Os dados secundĂĄrios consultados referem-se a resultados de pesquisas e estudos realizados nos Ășltimos 10 anos na regiĂŁo pela Embrapa Solos e outras instituiçÔes de pesquisa e/ou ensino, e de projetos que complementam e integram temas de interesse comum. Os dados primĂĄrios foram coletados junto aos atores locais (produtores rurais familiares e seus representantes, funcionĂĄrios de instituiçÔes pĂșblicas, empreendedores rurais, proprietĂĄrios de meios de hospedagem, entre outros), por meio de campanhas de campo realizadas entre 2012 e 2014, nas comunidades rurais produtivas com base na agricultura familiar. O conjunto de dados inventariados e a sĂntese do diagnĂłstico obtido serviram de base para a elaboração do plano preliminar. A presente versĂŁo intitulada: "Plano Preliminar para o Desenvolvimento do Agroturismo em Cachoeiras de Macacu, RJ" representa um primeiro passo para orientar o planejamento do agroturismo integrado Ă produção agropecuĂĄria de base familiar no municĂpio. Sua efetivação envolve os poderes pĂșblicos estaduais e municipais e deve ser impulsionado pela comunidade, para garantir que a atividade se desenvolva em harmonia com suas expectativas e anseios.bitstream/item/142637/1/BPD-244-Desenv-Agroturismo-Cach-Macacu.pd
Seed abortion in the sexual counterpart of Brachiaria brizantha apomicts (Poaceae).
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