922 research outputs found
Tuning nonradiative lifetimes via molecular aggregation
We show that molecular aggregation can strongly influence the nonradiative
decay (NRD) lifetime of an electronic excitation. As a demonstrative example,
we consider a transition-dipole-dipole-interacting dimer whose monomers have
harmonic potential energy surfaces (PESs). Depending on the position of the NRD
channel (), we find that the NRD lifetime () can exhibit a completely different dependence on the
intermolecular-interaction strength. We observe that (i) for near
the Franck-Condon region, increases with the
interaction strength; (ii) for near the minimum of the monomer
excited PES, the intermolecular interaction has little influence on ; (iii) for near the classical turning point of the
monomer nuclear dynamics, on the other side of the minimum, decreases with the interaction strength. Our findings suggest design
principles for molecular systems where a specific fluorescence quantum yield is
desired
Quantum-classical transition and quantum activation of ratchet currents in the parameter space
The quantum ratchet current is studied in the parameter space of the
dissipative kicked rotor model coupled to a zero temperature quantum
environment. We show that vacuum fluctuations blur the generic isoperiodic
stable structures found in the classical case. Such structures tend to survive
when a measure of statistical dependence between the quantum and classical
currents are displayed in the parameter space. In addition, we show that
quantum fluctuations can be used to overcome transport barriers in the phase
space. Related quantum ratchet current activation regions are spotted in the
parameter space. Results are discussed {based on quantum, semiclassical and
classical calculations. While the semiclassical dynamics involves vacuum
fluctuations, the classical map is driven by thermal noise.Comment: 6 pages, 3 figure
Microcavity polariton-like dispersion doublet in resonant Bragg gratings
Periodic structures resonantly coupled to excitonic media allow the existence
of extra intragap modes ('Braggoritons'), due to the coupling between Bragg
photon modes and 3D bulk excitons. This induces unique and unexplored
dispersive features, which can be tailored by properly designing the photonic
bandgap around the exciton resonance. We report that one-dimensional
Braggoritons realized with semiconductor gratings have the ability to mimic the
dispersion of quantum-well microcavity polaritons. This will allow the
observation of new nonlinear phenomena, such as slow-light-enhanced nonlinear
propagation and an efficient parametric scattering at two 'magic frequencies'
Diagnóstico preliminar da agricultura familiar na Transamazônica: indicações para pesquisa e desenvolvimento.
bitstream/item/61073/1/CPATU-Doc105.pd
A Embrapa Amazônia Oriental e o agronegócio do dendê no Pará.
bitstream/item/27557/1/Doc257.pdfDisponível também on-line
Contribuições da Embrapa Amazônia Oriental para o agronegócio do dendê.
Setor produtivo; Pesquisa e desenvolvimento; Estado da arte; Proposta de pesquisa da Embrapa Amazônia Oriental com o amarelecimento fatal do dendezeiro
Glutathione increase by the n-butanoyl glutathione derivative (GSH-C4) inhibits viral replication and induces a predominant Th1 immune profile in old mice infected with influenza virus
During aging, glutathione (GSH) content declines and the immune system undergoes a
deficiency in the induction of Th1 response. Reduced secretion of Th1 cytokines, which is
associated with GSH depletion, could weaken the host defenses against viral infections.
We first evaluated the concentration of GSH and cysteine in organs of old mice; then, the
effect of the administration of the N-butanoyl GSH derivative (GSH-C4) on the response of
aged mice infected with influenza A PR8/H1N1 virus was studied through the determination
of GSH concentration in organs, lung viral titer, IgA and IgG1/IgG2a production and
Th1/Th2 cytokine profile.
Old mice had lower GSH than young mice in organs. Also the gene expression of
endoplasmic reticulum (ER) stress markers involved in GSH metabolism and folding of
proteins, i.e. Nrf2 and PDI, was reduced. Following infection, GSH content remained low
and neither infection nor GSH-C4 treatment affected Nrf2 expression. In contrast, PDI
expression was upregulated during infection and appeared counterbalanced by GSH-C4.
Moreover, the treatment with GSH-C4 increased GSH content in organs, reduced viral
replication and induced a predominant Th1 response.
In conclusion, GSH-C4 treatment could be used in the elderly to contrast influenza virus
infection by inducing immune response, in particular the Th1 profile
On the applications of a compact autonomous acoustic recorder
A number of acoustic A compact acoustic recorder, primarily designed for underwater noise monitoring, is presented in this paper. The Self-Register Hydrophone has been used in several occasions during the past three years, in underwater noise monitoring activities. However, this kind of device also find application in other areas such as array processing and passive acoustic monitoring of marine mammals. An overview on the application of the Self-Register Hydrophone is given herein
BRSMG Curinga: cultivar de arroz lançada para as condições de terra firme no Estado do Pará.
bitstream/item/27801/1/Com.Tec.216.pdfVersão eletrônica. 1ª impressão: 2010
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