33,163 research outputs found
The complex channel networks of bone structure
Bone structure in mammals involves a complex network of channels (Havers and
Volkmann channels) required to nourish the bone marrow cells. This work
describes how three-dimensional reconstructions of such systems can be obtained
and represented in terms of complex networks. Three important findings are
reported: (i) the fact that the channel branching density resembles a power law
implies the existence of distribution hubs; (ii) the conditional node degree
density indicates a clear tendency of connection between nodes with degrees 2
and 4; and (iii) the application of the recently introduced concept of
hierarchical clustering coefficient allows the identification of typical scales
of channel redistribution. A series of important biological insights is drawn
and discussedComment: 3 pages, 1 figure, The following article has been submitted to
Applied Physics Letters. If it is published, it will be found online at
http://apl.aip.org
Gauge fields in a string-cigar braneworld
In this work we investigate the properties of an Abelian gauge vector field
in a thin and in a smoothed string-like braneworld, the so-called string-cigar
model. This thick brane scenario satisfies the regularity conditions and it can
be regarded as an interior and exterior string-like solution. The source
undergoes a geometric Ricci flow which is connected to a variation of the bulk
cosmological constant. The Ricci flow changes the width and amplitude of the
massless mode at the brane core and recover the usual thin string-like behavior
at large distances. By numerical means we obtain the Kaluza-Klein (KK) spectrum
for both the thin brane and the string-cigar. It turns out that both models
exhibit a mass gap between the massless and the massive modes and between the
high and the low mass regimes. The KK modes are smooth near the brane and their
amplitude are enhanced by the string-cigar core. The analogue Schr\"odinger
potential is also tuned by the geometric flow.Comment: The discussion about the Kaluza-Klein spectrum of the gauge field was
improved. Numerical analysis was adapted to the conventional notation on
Kaluza-Klein number. Some graphics were modified for considering other
notation. Results unchanged. References added. Corrected typos. 17 pages. 6
figures. To match version to appears in Physics Letters
Critical Behavior of a Three-State Potts Model on a Voronoi Lattice
We use the single-histogram technique to study the critical behavior of the
three-state Potts model on a (random) Voronoi-Delaunay lattice with size
ranging from 250 to 8000 sites. We consider the effect of an exponential decay
of the interactions with the distance,, with , and
observe that this system seems to have critical exponents and
which are different from the respective exponents of the three-state Potts
model on a regular square lattice. However, the ratio remains
essentially the same. We find numerical evidences (although not conclusive, due
to the small range of system size) that the specific heat on this random system
behaves as a power-law for and as a logarithmic divergence for
and Comment: 3 pages, 5 figure
Majority-Vote Model on a Random Lattice
The stationary critical properties of the isotropic majority vote model on
random lattices with quenched connectivity disorder are calculated by using
Monte Carlo simulations and finite size analysis. The critical exponents
and are found to be different from those of the Ising and
majority vote on the square lattice model and the critical noise parameter is
found to be .Comment: 4 pages, 6 figure
Análise de um projeto político pedagógico implementado em Belém do Pará
O presente estudo aborda o tema Projeto Político Pedagógico e tem como meta compreender a estrutura teórica de um projeto, fazendo um paralelo com o que de fato acontece na prática dentro de uma escola privada que já possui o seu PPP estruturado. Procuramos conhecer e analisar como ocorreu a elaboração do Projeto Político Pedagógico, assim como identificar as percepções dos educadores, as implicações e eventuais contradições entre o que é exigido por lei e o real das escolas e confrontar o PPP como instrumento norteador do fazer pedagógico e analisar se os objetivos postos são alcançados. Visamos a análise de um exemplo do que acontece nas instituições de ensino, servindo como guia para uma melhor prática educacional. A vertente empírica do estudo, para além da análise bibliográfica, contou com um importante corpus de dados qualitativos, recolhidos por meio de entrevistas individuais semiestruturadas, baseadas em um guião devidamente validado. A análise feita dos depoimentos das participantes do estudo sugere que o Projeto Político Pedagógico constitui para elas um núcleo de desenvolvimento das ações, assim como referência para eventuais dúvidas, para uma escola. Porém, demonstraram insatisfação de não terem mais detalhamento sobre o projeto por parte da gestão, mas acreditam que apesar de não se ter feito uma divulgação maior, conseguem manter os objetivos comuns. Contudo, consideram necessário reavaliar, assim como ouvir cada setor antes de reestruturar um novo documento; ABSTRACT: This research approaches the topic Political-Pedagogic Project (PPP) and it aims to comprehend the theoretical framework of a project, drawing a parallel with what actually happens in a private school which already has its own structured PPP. With this work, we seek to know and examine how the elaboration of the Political-Pedagogic Project occurred, as well as to identify the perceptions of educators, its implications and possible contradictions between what is required by law and the school reality and also view the PPP as a guiding tool for the school guidelines and examine whether the goals proposed are achieved. We aim mainly to explore an example of what happens in educational institutions and a guide to a better educational practice. The empirical aspects of the study, in addition to the bibliographic analysis, had an important corpus of qualitative data collected through semi-structured individual interviews, based on a script properly validated. The analysis of the testimonies of the study participants suggests that the Political-Pedagogic Project constituted for them the center of development actions, as well as a reference for possible doubts for a school. They demonstrated, however, disappointment since they have no access to the details of the project, but they believe that although there is no greater disclosure, they have managed to maintain the common goals. However, they need to review, as well as listen to each school sector before they restructure a new document
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