2,249 research outputs found
Contribuição de poleiros naturais e artificiais para a recuperação de ecossistemas florestais.
Resumo
Características das espécies vegetais dispersas por aves e morcegos e suas implicações na recuperação ou manutenção de ambientes florestais.
Editores técnicos: Marcílio José Thomazini, Elenice Fritzsons, Patrícia Raquel Silva, Guilherme Schnell e Schuhli, Denise Jeton Cardoso, Luziane Franciscon. EVINCI. Resumos
Mutirões de trabalho em agroflorestas agroecológicas: variações e padrões nas atividades e práticas.
Towards a European master programme on global software engineering
This paper presents a European Master programme on global software engineering (SE), being put forward by four leading institutions from Sweden, UK, Netherlands and Italy. The Global SE European Master (GSEEM) programme aims to provide students with an excellence in SE based on sound theoretical foundations and practical experience, as well as prepare them to participate in global development of complex and large software systems. GSEEM has been designed with three noteworthy aspects: 1) Three specialization profiles in which the consortium excels: Software Architecting, Real-time Embedded Systems Engineering, and Web Systems and Services Engineering. 2) Two market-driven routes: "professional" to work as professionals, and "scientific" to continue the education towards research degrees. 3) An innovative concept of "shared modules", delivered together by multiple institutions. Four types of shared modules are foreseen: "parallel" twin modules which run remotely between universities, "shifted" modules which teach SE concepts incrementally with shifts in study locations and timeline ,"complementary" modules in which complementary SE concepts are taught in parallel through shared projects, and "common" modules which share the presentations and the project. The profiles realize "integrated knowledge" by complementing partial knowledge available at partner institutions. The paper explains how GSEEM achieves the objectives of educating global software engineers
Accurate free and forced rotational motions of rigid Venus
% context :The precise and accurate modelling of a terrestrial planet like
Venus is an exciting and challenging topic, all the more interesting since it
can be compared with that of the Earth for which such a modelling has already
been achieved at the milliarcsecond level % aims: We want to complete a
previous study (Cottereau and Souchay, 2009), by determining at the
milliarcsecond level the polhody, i.e. the torque-free motion of the axis of
angular momentum of a rigid Venus in a body-fixed frame, as well as the
nutation of its third axis of figure in space, which is fundamental from an
observational point of view. results :In a first part we have computed the
polhody, i.e. the respective free rotational motion of the axis of angular
momentum of Venus with respect to a body-fixed frame. We have shown that this
motion is highly elliptical, with a very long period of 525 cy to be compared
with 430 d for the Earth. This is due to the very small dynamical flattening of
Venus in comparison with our planet. In a second part we have computed
precisely the Oppolzer terms which allow to represent the motion in space of
the third Venus figure axis with respect to Venus angular momentum axis, under
the influence of the solar gravitational torque. We have determined the
corresponding tables of coefficients of nutation of the third figure axis both
in longitude and in obliquity due to the Sun, which are of the same order of
amplitude as for the Earth. We have shown that the coefficients of nutation for
the third figure axis are significantly different from those of the angular
momentum axis on the contrary of the Earth. Our analytical results have been
validated by a numerical integration which revealed the indirect planetary
effects.Comment: 14 pages, 11 figures, accepted for publication in section 11.
Celestial mechanics and astrometry of Astronomy and Astrophysics (27/02/2010
The structure of an endogenous Drosophila centromere reveals the prevalence of tandemly repeated sequences able to form i-motifs
Centromeres are the chromosomal loci at which spindle microtubules attach to mediate chromosome segregation during mitosis and meiosis. In most eukaryotes, centromeres are made up of highly repetitive DNA sequences (satellite DNA) interspersed with middle repetitive DNA sequences (transposable elements). Despite the efforts to establish complete genomic sequences of eukaryotic organisms, the so-called 'finished' genomes are not actually complete because the centromeres have not been assembled due to the intrinsic difficulties in constructing both physical maps and complete sequence assemblies of long stretches of tandemly repetitive DNA. Here we show the first molecular structure of an endogenous Drosophila centromere and the ability of the C-rich dodeca satellite strand to form dimeric i-motifs. The finding of i-motif structures in simple and complex centromeric satellite DNAs leads us to suggest that these centromeric sequences may have been selected not by their primary sequence but by their ability to form noncanonical secondary structures.Peer Reviewe
Atividades e práticas em coletivos de trabalho - mutirões - em agroflorestas agroecológicas do litoral do Paraná, Brasil.
O objetivo desse trabalho é a caracterização, análise e discussão das ações praticadas nos mutirões do Grupo de Produtores Agroflorestais Gralha Azul, de Morretes-PR. Dezesseis mutirões do grupo foram acompanhados. As atividades realizadas foram: preparo de canteiro (12 mutirões) e plantio de frutíferas (4). Houve dois tipos de preparo de canteiro: mecanizado e não mecanizado. No mecanizado, com enxada rotativa, em média 7 agricultores em cerca de 6 horas fizeram 121,8 m² de canteiros com largura fixa de 1,20m. Já no não mecanizado, a média foi de 6 agricultores trabalhando cerca de 6 horas fazendo 65,3m² de canteiro com largura média de 0,56 m. Em média nos plantios de frutíferas 6 agricultores trabalharam cerca de 4 horas. A preferência por estas atividades é reflexo tanto do aproveitamento de mão de obra para trabalhos mais árduos quanto pelo fato que a agrofloresta é uma atividade recente. As práticas observadas são recomendações técnicas baseadas na troca de saberes que acontecem entre os técnicos e agricultores e seguem fundamentos agroecológicos.Edição dos resumos do 7º Congresso Brasileiro de Agroecologia, 2013, Porto Alegre
The Power of Non-Determinism in Higher-Order Implicit Complexity
We investigate the power of non-determinism in purely functional programming
languages with higher-order types. Specifically, we consider cons-free programs
of varying data orders, equipped with explicit non-deterministic choice.
Cons-freeness roughly means that data constructors cannot occur in function
bodies and all manipulation of storage space thus has to happen indirectly
using the call stack.
While cons-free programs have previously been used by several authors to
characterise complexity classes, the work on non-deterministic programs has
almost exclusively considered programs of data order 0. Previous work has shown
that adding explicit non-determinism to cons-free programs taking data of order
0 does not increase expressivity; we prove that this - dramatically - is not
the case for higher data orders: adding non-determinism to programs with data
order at least 1 allows for a characterisation of the entire class of
elementary-time decidable sets.
Finally we show how, even with non-deterministic choice, the original
hierarchy of characterisations is restored by imposing different restrictions.Comment: pre-edition version of a paper accepted for publication at ESOP'1
Magnetic Monopole Dynamics in Spin Ice
One of the most remarkable examples of emergent quasi-particles, is that of
the "fractionalization" of magnetic dipoles in the low energy configurations of
materials known as "spin ice", into free and unconfined magnetic monopoles
interacting via Coulomb's 1/r law [Castelnovo et. al., Nature, 451, 42-45
(2008)]. Recent experiments have shown that a Coulomb gas of magnetic charges
really does exist at low temperature in these materials and this discovery
provides a new perspective on otherwise largely inaccessible phenomenology. In
this paper, after a review of the different spin ice models, we present
detailed results describing the diffusive dynamics of monopole particles
starting both from the dipolar spin ice model and directly from a Coulomb gas
within the grand canonical ensemble. The diffusive quasi-particle dynamics of
real spin ice materials within "quantum tunneling" regime is modeled with
Metropolis dynamics, with the particles constrained to move along an underlying
network of oriented paths, which are classical analogues of the Dirac strings
connecting pairs of Dirac monopoles.Comment: 26 pages, 12 figure
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