21,703 research outputs found
Altruism, Fertility, and the Value of Children: Health Policy Evaluation and Intergenerational Welfare
This paper accounts for the value of children and future generations in the evaluation of health policies. This is achieved through the incorporation of altruism and fertility in "value of life" type of framework. We are able to express adults' willingness to pay for changes in child mortality and also to incorporate the welfare of future generations in the evaluation of current policies. Our model clarifies a series of puzzles from the literature on the "value of life" and on intergenerational welfare comparisons. We show that, by incorporating altruism and fertility into the analysis, the estimated welfare gain from recent reductions in mortality in the U.S. easily doubles.
Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|
The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the
rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little
theoretical uncertainty, provided the hadronic form factor for the B -> pi
transition can be measured from some other B decay. In here, we suggest using
the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be
properly described within the usual factorization approximation; we use instead
a simple and very general phenomenological model for the b d J\psi vertex. In
order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l
+ antineutrino_l decays, we use form factor relations that hold for
heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure
Avaliação de ferramentas para detecção de interações epistáticas para fenótipos quantitativos em estudos de associação genômica ampla.
Variações genéticas presentes em uma população podem estar associadas a muitas características como susceptibilidade a doenças em humanos (ex: diabetes, câncer, e doenças psiquiátricas). Atualmente, tecnologias de genotipagem de baixo custo, baseadas em marcadores moleculares do tipo polimorfismo de base única Single Nucleotide Polymorphism (SNP) são utilizados para identificar variações desse tipo associadas com doenças. Tais estudos, são denominados, estudos de associação genômica ampla, Genome Wide Association Studies (GWAS). No caso de espécies de interesse agropecuário, essas variações genéticas estão relacionadas a características que podem impactar ganhos de qualidade e produção. Portanto, é de extrema importância a utilização de novos métodos computacionais para identificação desses marcadores, já que isto pode contribuir para a seleção de indivíduos superiores, considerando os traços fenotípicos de interesse em espécies animais utilizadas em programas de melhoramento coordenados pela Empresa Brasileira de Pesquisa Agropecuária (Embrapa)
An extended formalism for preferential attachment in heterogeneous complex networks
In this paper we present a framework for the extension of the preferential
attachment (PA) model to heterogeneous complex networks. We define a class of
heterogeneous PA models, where node properties are described by fixed states in
an arbitrary metric space, and introduce an affinity function that biases the
attachment probabilities of links. We perform an analytical study of the
stationary degree distributions in heterogeneous PA networks. We show that
their degree densities exhibit a richer scaling behavior than their homogeneous
counterparts, and that the power law scaling in the degree distribution is
robust in presence of heterogeneity
On the quantumness of correlations in nuclear magnetic resonance
Nuclear Magnetic Resonance (NMR) was successfully employed to test several
protocols and ideas in Quantum Information Science. In most of these
implementations the existence of entanglement was ruled out. This fact
introduced concerns and questions about the quantum nature of such bench tests.
In this article we address some issues related to the non-classical aspects of
NMR systems. We discuss some experiments where the quantum aspects of this
system are supported by quantum correlations of separable states. Such
quantumness, beyond the entanglement-separability paradigm, is revealed via a
departure between the quantum and the classical versions of information theory.
In this scenario, the concept of quantum discord seems to play an important
role. We also present an experimental implementation of an analogous of the
single-photon Mach-Zehnder interferometer employing two nuclear spins to encode
the interferometric paths. This experiment illustrate how non-classical
correlations of separable states may be used to simulate quantum dynamics. The
results obtained are completely equivalent to the optical scenario, where
entanglement (between two field modes) may be present
Group theory for structural analysis and lattice vibrations in phosphorene systems
Group theory analysis for two-dimensional elemental systems related to
phosphorene is presented, including (i) graphene, silicene, germanene and
stanene, (ii) dependence on the number of layers and (iii) two stacking
arrangements. Departing from the most symmetric graphene space
group, the structures are found to have a group-subgroup relation, and analysis
of the irreducible representations of their lattice vibrations makes it
possible to distinguish between the different allotropes. The analysis can be
used to study the effect of strain, to understand structural phase transitions,
to characterize the number of layers, crystallographic orientation and
nonlinear phenomena.Comment: 24 pages, 3 figure
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