1,578 research outputs found
Non-Equilibrium Modeling of the Fe XVII 3C/3D ratio for an Intense X-ray Free Electron Laser
We present a review of two methods used to model recent LCLS experimental
results for the 3C/3D line intensity ratio of Fe XVII (Bernitt et al. 2012),
the time-dependent collisional-radiative method and the density-matrix
approach. These are described and applied to a two-level atomic system excited
by an X-ray free electron laser. A range of pulse parameters is explored and
the effects on the predicted Fe XVII 3C and 3D line intensity ratio are
calculated. In order to investigate the behavior of the predicted line
intensity ratio, a particular pair of A-values for the 3C and 3D transitions
was chosen (2.22 10 s and 6.02 10
s for the 3C and 3D, respectively), but our conclusions are independent
of the precise values. We also reaffirm the conclusions from Oreshkina et
al.(2014, 2015): the non-linear effects in the density matrix are important and
the reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to the
laser pulse parameters, namely pulse duration, pulse intensity, and laser
bandwidth. It is also shown that for both models the lowering of the 3C/3D line
intensity ratio below the expected time-independent oscillator strength ratio
has a significant contribution due to the emission from the plasma after the
laser pulse has left the plasma volume. Laser intensities above W/cm are required for a reduction in the 3C/3D line intensity
ratio below the expected time independent oscillator strength ratio
Scaling Limit and Critical Exponents for Two-Dimensional Bootstrap Percolation
Consider a cellular automaton with state space
where the initial configuration is chosen according to a Bernoulli
product measure, 1's are stable, and 0's become 1's if they are surrounded by
at least three neighboring 1's. In this paper we show that the configuration
at time n converges exponentially fast to a final configuration
, and that the limiting measure corresponding to is in
the universality class of Bernoulli (independent) percolation.
More precisely, assuming the existence of the critical exponents ,
, and , and of the continuum scaling limit of crossing
probabilities for independent site percolation on the close-packed version of
(i.e., for independent -percolation on ), we
prove that the bootstrapped percolation model has the same scaling limit and
critical exponents.
This type of bootstrap percolation can be seen as a paradigm for a class of
cellular automata whose evolution is given, at each time step, by a monotonic
and nonessential enhancement.Comment: 15 page
Resinose do coqueiro: como identificar essa doença.
bitstream/CPATC-2009-09/20372/1/f_15_2008.pd
Acima dos confrontos sobre os transgênicos: uma experiência piloto de consulta pública.
RESUMO: A tecnologia do DNA recombinante abriu, juntamente com um horizonte ilimitado de possibilidades de inovações, polêmicas que não podem ser ignoradas ou resolvidas por meio de uma difusão linear de informações. Ações multidisciplinares e multi-institucionais têm sido implementadas, com sucesso, em diversos países, para estabelecer novas formas de comunicação entre peritos e leigos. Isso permite identificar possíveis restrições e benefícios nas trajetórias tecnológicas, e assim entender e negociar eventuais conflitos. No Brasil, esse tipo de abordagem não tem recebido atenção significativa. A metodologia Problem Formulation and Options Assessment (PFOA), articulada no contexto do projeto internacional Genetically Modified Organisms - Environmental Risk Assessment (GMO-ERA), e sintonizada com as novas tendências de envolvimento dos diversos setores de interesse (stakeholders) ligados a uma tecnologia, propõe integrar na análise de risco as perspectivas ambiental, social, econômica e ética. A equipe de implementação de uma experiência piloto do PFOA foi formada pelo grupo do GMOERA - ligado ao Projeto Rede de Biossegurança (BioSeg), da Empresa Brasileira de Pesquisa Agropecuária (Embrapa), pelo Instituto de Pesquisa em Riscos e Sustentabilidade, da Universidade Federal de Santa Catarina (Iris-UFSC), e pelo Centro de Gestão de Estudos Estratégicos do Ministério da Ciência e Tecnologia (CGEE/MCT). O caso utilizado como modelo foi o feijão geneticamente modificado resistente ao mosaico-dourado, que vem sendo desenvolvido pela Embrapa. O piloto, financiado pelo CGEE/MCT, contou com a participação de diversos stakeholders. Dentre as conclusões, recomenda-se o uso de sistemas de informação não unidirecionados, mais transparentes e abertos, baseados em uma ciência rigorosa, para subsidiar as instâncias científicas e políticas nas tomadas de decisão. abstract: Recombinant DNA technology, together with an unlimited horizon of possibilities of innovation, triggered a discussion, among stakeholders, that cannot be ignored or solved through a linear difusion of information. Multidisciplinary and multi-institutional actions are being successfully adopted in several countries to establish new communication strategies between specialists and stakeholders. These strategies allow the identification of possible constraints and benefits of a technology during its development and, consequently, understanding and negotiation of conflicts. In Brazil this approach is not being used yet. The Problem Formulation and Options Assessment (PFOA) methodology was proposed by the Genetically Modified Organisms - Environmental Risk Assessment (GMO-ERA) project, aligned with the new trend of involving stakeholders in the risk assessment of a new technology. PFOA integrates the environmental, social, economic and ethical perspectives into the risk assessment of a technology. PFOA's pilot experience was conducted by a group formed by the GMO-ERA team associated with the Biosafety Network (BioSeg) project of the Brazilian Agricultural Research Corporation (Embrapa), by the Institute of Research in Risk and Sustainability from the Federal University of Santa Catarina (Iris-UFSC) and by the Center for Strategic Management and Studies in Science, Technology and Innovation of the Ministry of Science and Technology (CGEE/ MCT). The case study was a genetically modified bean resistant to the golden mosaic disease, which is being developed by Embrapa. This pilot was funded by CGEE/MCT and gathered representatives of several stakeholders. It could be concluded that the use of non-directed, transparent, open and science-based communication approaches is of great value for scientific and political decision making instances
Side Effects of Human Drug Use: An Overview of the Consequences of Eels’ Exposure to Cocaine
The widespread use of drugs is a global problem which affects not only humans but also
the environment around them, as research is showing the presence of these substances in different
environmental matrices, like air, water, and soil. Above all, due to the remarkable pharmacological
properties of drugs, it is discovered that organisms accidentally exposed to them, as aquatic organisms,
undergo behavioral and physiological changes that can compromise their health, survival, and
reproduction ability. In addition to this, we must consider the ability of some drugs to accumulate
within these organisms, thus entering the food chain, and the possible interactions that drugs in water
can establish with each other and with other possible pollutants, making the final effects on exposed
organisms unpredictable. This article is an overview of the effects of one of these drugs, cocaine, one
of the drugs commonly found in the aquatic environment, on European eel, an endangered species
and known biomonitor of aquatic contaminatio
Thermal phase diagrams of columnar liquid crystals
In order to understand the possible sequence of transitions from the
disordered columnar phase to the helical phase in hexa(hexylthio)triphenylene
(HHTT), we study a three-dimensional planar model with octupolar interactions
inscribed on a triangular lattice of columns. We obtain thermal phase diagrams
using a mean-field approximation and Monte Carlo simulations. These two
approaches give similar results, namely, in the quasi one-dimensional regime,
as the temperature is lowered, the columns order with a linear polarization,
whereas helical phases develop at lower temperatures. The helicity patterns of
the helical phases are determined by the exact nature of the frustration in the
system, itself related to the octupolar nature of the molecules.Comment: 12 pages, 9 figures, ReVTe
Padrão de emergência de adultos do bicudo do algodoeiro, Anthonomus grandis, ao longo da safra e entressafra na região Centro-Oeste.
bitstream/item/111269/1/bpd332-2011.pd
Efeito de diferentes doses de inseticidas no controle do bicudo do algodoeiro Anthonomus grnadis BOHEMAN, 1843.
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