2,511 research outputs found
Collaboration networks from a large CV database: dynamics, topology and bonus impact
Understanding the dynamics of research production and collaboration may
reveal better strategies for scientific careers, academic institutions and
funding agencies. Here we propose the use of a large and multidisciplinar
database of scientific curricula in Brazil, namely, the Lattes Platform, to
study patterns of scientific production and collaboration. In this database,
detailed information about publications and researchers are made available by
themselves so that coauthorship is unambiguous and individuals can be evaluated
by scientific productivity, geographical location and field of expertise. Our
results show that the collaboration network is growing exponentially for the
last three decades, with a distribution of number of collaborators per
researcher that approaches a power-law as the network gets older. Moreover,
both the distributions of number of collaborators and production per researcher
obey power-law behaviors, regardless of the geographical location or field,
suggesting that the same universal mechanism might be responsible for network
growth and productivity.We also show that the collaboration network under
investigation displays a typical assortative mixing behavior, where teeming
researchers (i.e., with high degree) tend to collaborate with others alike.
Finally, our analysis reveals that the distinctive collaboration profile of
researchers awarded with governmental scholarships suggests a strong bonus
impact on their productivity.Comment: 8 pages, 8 figure
A universal approach for drainage basins
Drainage basins are essential to Geohydrology and Biodiversity. Defining
those regions in a simple, robust and efficient way is a constant challenge in
Earth Science. Here, we introduce a model to delineate multiple drainage basins
through an extension of the Invasion Percolation-Based Algorithm (IPBA). In
order to prove the potential of our approach, we apply it to real and
artificial datasets. We observe that the perimeter and area distributions of
basins and anti-basins display long tails extending over several orders of
magnitude and following approximately power-law behaviors. Moreover, the
exponents of these power laws depend on spatial correlations and are invariant
under the landscape orientation, not only for terrestrial, but lunar and
martian landscapes. The terrestrial and martian results are statistically
identical, which suggests that a hypothetical martian river would present
similarity to the terrestrial rivers. Finally, we propose a theoretical value
for the Hack's exponent based on the fractal dimension of watersheds,
. We measure for Earth, which is close to
our estimation of . Our study suggests that Hack's law can
have its origin purely in the maximum and minimum lines of the landscapes.Comment: 20 pages, 6 Figures, and 1 Tabl
Efeito do processamento térmico nas propriedades físico-químicas e microbiológicas do suco de tangerina var. Murcott.
Transparência de tecnologia contextualizada: estudo de caso no Semiárido paraibano.
O artigo apresenta uma análise multidimensional sobre a estratégia de intervenção do Cooperar/PB-BIRD com o objetivo de reduzir a extrema pobreza no Estado da Paraíba. A partir da difusão de tecnologias adaptadas as reais necessidades e interesses das famílias rurais e as peculiaridades do semiárido, isto é, Transferência de Tecnologia Contextualizada (TTC), fundamentada na construção de um Índice de Sustentabilidade de Investimentos de Politicas Públicas (IPP), com a finalidade de monitorar e avaliar sua consecução. O IPP possibilitou que, associar-se a cada base municipal, o Acervo Tecnológico, hoje existente, voltado para a sustentabilidade dos Arranjos Produtivos Locais (APLs). O processo de TTC em marcha na Paraíba disciplina as atividades na esfera estadual, municipal e local, em base sustentável. Enquanto, o IPP pautado em valores adicionados brutos a preço corrente da agropecuária, torna possível mensurar para cada um dos 222 municípios, seus graus de sustentabilidade de aplicação de investimentos de políticas pública por habitante Rural, antes e posterior sua consecução
Thermal analysis of photon-like particles in rainbow gravity
This work is devoted to study the thermodynamic behavior of photon--like
particles within the \textit{rainbow} gravity formalism. To to do this, we
chose two particular ansatzs to accomplish our calculations. First, we consider
a dispersion relation which avoids UV divergences, getting a positive effective
cosmological constant. We provide \textit{numerical} analysis for the
thermodynamic functions of the system and bounds are estimated. Furthermore, a
phase transition is also expected for this model. Second, we consider a
dispersion relation employed in the context of \textit{Gamma Ray Bursts}.
Remarkably, for this latter case, the thermodynamic properties are calculated
in an \textit{analytical} manner and they turn out to depend on the harmonic
series , gamma , polygamma and zeta Riemann
functions .Comment: 22 pages, 7 figure
Efeito do tratamento térmico na concentração de carotenóides, compostos fenólicos, ácido ascórbico e capacidade antioxidante do suco de tangerina murcote.
Thermodynamical properties of an ideal gas in a traversable wormhole
In this work, we analyze the thermodynamic properties of non--interacting
particles under influence of the gravitational field of a traversable wormhole.
In particular, we investigate how the thermodynamic quantities are affected by
the Ellis wormhole geometry, considering three different regions to our study:
asymptotically far, close to the throat, and at the throat. The thermodynamic
quantities turn out to depend strongly on parameter that controls the wormhole
throat radius. By varying it, there exist an expressive modification in the
thermodynamic state quantities, exhibiting both usual matter and dark
energy--like behaviors. Finally, the interactions are regarded to the energy
density and it seems to indicate that it "cures" the dark energy--like
features.Comment: 29 pages and 18 figure
The Noncommutative Anandan's Quantum Phase
In this work we study the noncommutative nonrelativistic quantum dynamics of
a neutral particle, that possesses permanent magnetic and electric dipole
momenta, in the presence of an electric and magnetic fields. We use the
Foldy-Wouthuysen transformation of the Dirac spinor with a non-minimal coupling
to obtain the nonrelativistic limit. In this limit, we will study the
noncommutative quantum dynamics and obtain the noncommutative Anandan's
geometric phase. We analyze the situation where magnetic dipole moment of the
particle is zero and we obtain the noncommutative version of the
He-McKellar-Wilkens effect. We demonstrate that this phase in the
noncommutative case is a geometric dispersive phase. We also investigate this
geometric phase considering the noncommutativity in the phase space and the
Anandan's phase is obtained.Comment: 15 pages, revtex4, version to appear in Physical Review
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