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Francoso R.D.,University of Brasilia | Haidar R.F.,Campus Universitario Darcy Ribeiro | Machado R.B.,University of Brasilia
Acta Botanica Brasilica

Biological knowledge is important for guidance of conservation polices. In the Cerrado, an extremely diverse biome, the last synthesis of floristic knowledge has more than ten years. To understand the progress on the information, our aim was quantify the tree species of the Cerrado, and assess their distribution. We compiled 167 inventories and rapid surveys of tree species, corresponding to 625 sites. We accessed the species distributions in the Brazilian biomes, and estimated the number of species in the savannas of Cerrado using four algorithms. We observed a greater local richness in more central regions of the biome, but due to high beta diversity, more peripheral regions presented a greater cumulative richness. The Atlantic Forest was the most important neighbouring biome, influencing the floristic composition of the Cerrado. The proportion of typical Cerrado species was 16%. The highest proportion of endemic species is possibly found in other life forms, and it is crucial that these species are included in inventories and floristic surveys. To guide new studies and help supplement the knowledge of the Cerrado’s flora, we identified the main sampling gaps, located mainly in ecotonal regions, which are responsible for the largest number of species recorded in studies of the Cerrado. © 2016, Sociedade Botanica do Brasil. All rights reserved. Source

Lunardi V.O.,University of Brasilia | Lunardi V.O.,Rural University | MacEdo R.H.,Campus Universitario Darcy Ribeiro
Wilson Journal of Ornithology

The Wilson's Plover (Charadrius wilsonia) is widely distributed along the coast of the Americas. We present the first reproductive record in Baa de Todos os Santos, Brazil, broadening the southernmost limit of its breeding area along the Atlantic Coast to 12° 44′ S, 38° 45′ W. We recorded a family with a subadult in 2007, and a family with chicks and a nest in 2008. The female invested more time in incubation than the male in 96 hrs of diurnal nest observations. There were 102 interruptions during incubation due to the approximation of domestic animals (cattle and horses). The nest was abandoned 9 days after egg laying. An experiment with artificial nests suggests that 30 of Wilson's Plover nests may be destroyed by free-ranging domestic animals in this Baa. © 2010 by the Wilson Ornithological Society. Source

Abade G.C.,University of Warsaw | Abade G.C.,Campus Universitario Darcy Ribeiro | Cichocki B.,University of Warsaw | Ekiel-Jeewska M.L.,Polish Academy of Sciences | And 2 more authors.
Journal of Chemical Physics

We determine the high-frequency limiting shear viscosity, η∞, in colloidal suspensions of rigid, uniformly porous spheres of radius a as a function of volume fraction φ and (inverse) porosity parameter x. Our study covers the complete fluid-state regime. The flow inside the spheres is modeled by the Debye-Bueche-Brinkman equation using the boundary condition that fluid velocity and stress change continuously across the sphere surfaces. The many-sphere hydrodynamic interactions in concentrated systems are fully accounted for by a precise hydrodynamic multipole method encoded in our HYDROMULTIPOLE program extended to porous particles. A truncated virial expansion is used to derive an accurate and easy-to-use generalized Saitô formula for η∞. The simulation data are used to test the performance of two simplifying effective particle models. The first model describes the effective particle as a nonporous sphere characterized by a single effective radius aeff (x) Source

Dutra J.D.L.,Federal University of Sergipe | Ferreira J.W.,Federal University of Sergipe | Rodrigues M.O.,Campus Universitario Darcy Ribeiro | Freire R.O.,Federal University of Sergipe
Journal of Physical Chemistry A

When Judd-Ofelt intensity parameters of polynuclear compounds with asymmetric centers are calculated using the current procedure, the results are inconsistent. The problem arises from the fact that the experimental intensity parameters cannot be determined for each asymmetric polyhedron, and this precludes the individual theoretical adjustment. In this study, we then propose three different methods for calculation of these parameters of polyeuropium systems. The first, named the centroid method, proposes the calculation considering the center of the dimeric system as the half distances between the two europium centers. The second method, called the overlapped polyhedra method, proposes the calculation considering the overlapping of both europium polyhedra, and the last one, the individual polyhedron method, proposes the use of theoretical mean values of charge factors and polarizabilities associated with each europium-ligand atom bond to calculate the intensity parameters. One symmetric polyeuropium system and one asymmetric system were assessed by using the three methods. Among the methods assessed, the one based on the overlapped polyhedra produced more consistent results for the study of both kinds of systems. © 2013 American Chemical Society. Source

Abade G.C.,University of Warsaw | Abade G.C.,Campus Universitario Darcy Ribeiro | Cichocki B.,University of Warsaw | Lekiel-Jezewska M.L.,Polish Academy of Sciences | And 2 more authors.
Journal of Physics Condensed Matter

We study the high-frequency limiting shear viscosity, η ∞ of colloidal suspensions of uncharged porous particles. An individual particle is modeled as a uniformly porous sphere with the internal solvent flow described by the Debye-Bueche-Brinkman equation. A precise hydrodynamic multipole method with a full account of many-particle hydrodynamic interactions encoded in the hydromultipole program extended to porous particles, is used to calculate η∞ as a function of porosity and concentration. The second-order virial expansion for η∞ is derived, and its range of applicability assessed. The simulation results are used to test the validity of generalized Stokes-Einstein relations between η∞ and various short-time diffusion coefficients, and to quantify the accuracy of a simplifying cell model calculation of η∞ .An easy-to-use generalized Saito formula for η∞ is presented which provides a good description of its porosity and concentration dependence. © 2010 IOP Publishing Ltd. Source

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