4,262 research outputs found
Superexpressão do gene AltSB, aluminum tolerance Sorghum bicolor, em plantas transgências de milho.
Non-singular inflation with vacuum decay
On the basis of a semi-classical analysis of vacuum energy in an expanding
spacetime, we describe a non-singular cosmological model in which the vacuum
density decays with time, with a concomitant production of matter. During an
infinitely long period we have an empty, inflationary universe, with H \approx
1. This primordial era ends in a fast phase transition, during which H and
\Lambda decrease to nearly zero in a few Planck times, with release of a huge
amount of radiation. The late-time scenario is similar to the standard model,
with the radiation phase followed by a long dust era, which tends
asymptotically to a de Sitter universe, with vacuum dominating again. An
analysis of the redshift-distance relation for supernovas Ia leads to
cosmological parameters in agreement with other current estimations.Comment: Work presented at IRGAC 2006, Barcelona, July 11-15 2006. To appear
in a special issue of Journal of Physics
Milho Bt: teoria e prática da produção de plantas transgênicas resistentes a insetos-praga.
A biotecnologia moderna está gerando um grande número de genes passíveis de serem utilizados para a melhoria genética do milho, e as técnicas de transformação genética de plantas poderão ser empregadas para alterar a funcionalidade in vivo destes genes via complementação, superexpressão ou silenciamento. Progressos expressivos foram conseguidos no desenvolvimento da tecnologia de transformação genética de milho na última década. A transformação genética do milho, considerada por algum tempo problemática, tornou-se, atualmente, um procedimento de rotina para vários genótipos na maioria dos laboratórios públicos e privados trabalhando com esta cultura. Nesta Circular Técnica, serão abordados aspectos da produção e utilização em campo do milho Bt, englobando desde as pesquisas iniciais para o isolamento e caracterização dos genes cry, sua transferência para cultivares de milho via biobalística ou Agrobacterium, sua integração em programas de melhoramento clássico assistido por marcadores moleculares e utilização destas novas cultivares em campo.bitstream/CNPMS-2010/22708/1/Circ-135.pd
Monte-Carlo calculation of longitudinal and transverse resistivities in a model Type-II superconductor
We study the effect of a transport current on the vortex-line lattice in
isotropic type-II superconductors in the presence of strong thermal
fluctuations by means of 'driven-diffusion' Monte Carlo simulations of a
discretized London theory with finite magnetic penetration depth. We calculate
the current-voltage (I-V) characteristics for various temperatures, for
transverse as well as longitudinal currents I. From these characteristics, we
estimate the linear resistivities R_xx=R_yy and R_zz and compare these with
equilibrium results for the vortex-lattice structure factor and the helicity
moduli. From this comparison a consistent picture arises, in which the melting
of the flux-line lattice occurs in two stages for the system size considered.
In the first stage of the melting, at a temperature T_m, the structure factor
drops to zero and R_xx becomes finite. For a higher temperature T_z, the second
stage takes place, in which the longitudinal superconducting coherence is lost,
and R_zz becomes finite as well. We compare our results with related recent
numerical work and experiments on cuprate superconductors.Comment: 4 pages, with eps figure
Pseudo-dynamic method for structural analysis of automobile seats
This work describes the application of a pseudo-dynamic (PsD) method to the
dynamic analysis of passenger seats for the automotive industry. The project of such components
involves a structural test considering the action of dynamic forces arising from a
crash scenario. The laboratory certification of these automotive components consists essentially
on the inspection of the propagation and extension of plastic deformations zones in metallic
members of the seat structure as consequence of the mutual action between the seat and the
passenger fastened to the seat via seat belt anchorages. This work presents a relatively simple
experiment using PsD techniques as a novel method to performa test equivalent to the dynamic
model of a dummy-seat pair subjected to impulsive loads from a car crash.
Essentially, the PsD test method is a hybrid and hierarchic computer-driven testing procedure
where a numerical algorithm and experimental step are used and combined on-line in order to
solve a problem in the scope of structural dynamics. The implementation of the method is not
expensive and has the leading advantage of offering the operator a total control of any intermediate
structure state during the test still keeping the realism of a real dynamic testing.Project: NDT-AUTO Ref 13-02-2003-FDR-01281 (Agencia de Inovação
Continuous Time Monte Carlo and Spatial Ordering in Driven Lattice Gases: Application to Driven Vortices in Periodic Superconducting Networks
We consider the two dimensional (2D) classical lattice Coulomb gas as a model
for magnetic field induced vortices in 2D superconducting networks. Two
different dynamical rules are introduced to investigate driven diffusive steady
states far from equilibrium as a function of temperature and driving force. The
resulting steady states differ dramatically depending on which dynamical rule
is used. We show that the commonly used driven diffusive Metropolis Monte Carlo
dynamics contains unphysical intrinsic randomness that destroys the spatial
ordering present in equilibrium (the vortex lattice) over most of the driven
phase diagram. A continuous time Monte Carlo (CTMC) is then developed, which
results in spatially ordered driven states at low temperature in finite sized
systems. We show that CTMC is the natural discretization of continuum Langevin
dynamics, and argue that it gives the correct physical behavior when the
discrete grid represents the minima of a periodic potential. We use detailed
finite size scaling methods to analyze the spatial structure of the steady
states. We find that finite size effects can be subtle and that very long
simulation times can be needed to arrive at the correct steady state. For
particles moving on a triangular grid, we find that the ordered moving state is
a transversely pinned smectic that becomes unstable to an anisotropic liquid on
sufficiently large length scales. For particles moving on a square grid, the
moving state is a similar smectic at large drives, but we find evidence for a
possible moving solid at lower drives. We find that the driven liquid on the
square grid has long range hexatic order, and we explain this as a specifically
non-equilibrium effect. We show that, in the liquid, fluctuations are diffusive
in both the transverse and longitudinal directions.Comment: 29 pages, 35 figure
A framework for group decision-making: Including cognitive and affective aspects in a MCDA method for alternatives rejection
© Springer International Publishing AG, part of Springer Nature 2019. With the evolution of the organizations and technology, Group Decision Support Systems have changed to support decision-makers that cannot be together at the same place and time to make a decision. However, these systems must now be able to support the interaction between decision-makers and provide all the relevant information at the most adequate times. Failing to do so may compromise the success and the acceptance of the system. In this work it is proposed a framework for group decision using a Multiple Criteria Decision Analysis method capable of identify inconsistent assessments done by the decision-maker and identify alternatives that should be rejected by the group of decision-makers. The proposed framework allows to present more relevant information throughout the decision-making process and this way guide decision-makers in the achievement of more consensual and satisfactory decisions.INCT-EN - Instituto Nacional de Ciência e Tecnologia para Excitotoxicidade e Neuroproteção(ANI|P2020 21958
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