427 research outputs found
O design educacional para a modalidade a distância em uma perspectiva inclusiva: contribuições para/na formação docente.
Este estudo, de cunho qualitativo, analisou o Design Educacional para a modalidade a distância no Centro de Educação a Distância do Instituto Federal do EspÃrito Santo recorrendo a uma pesquisa-ação com três grupos focais: Grupo 1 - equipe de produção de recursos educacionais; Grupo 2 - professores-formadores em Educação a Distância e Grupo 3 - alunosprofessores do curso de Capacitação em Práticas para Educação a Distância para Professores na modalidade a distância. O Design Educacional envolve diferentes áreas de conhecimento e aportes teóricos, sendo que este estudo optou pelas contribuições de Piaget e de Vigotski no que se refere ao processo de aprendizagem e interação social; Moore e Kearsley, nas questões que envolvem a Educação a Distância; Filatro e Torezzan para o Design Instrucional. Nas discussões suscitadas no Grupo 1, da equipe de produção de recursos educacionais, foram identificadas dentre várias questões, as principais dificuldades e desafios do Design Educacional na sociedade contemporânea. A coleta de dados e a análise dos resultados dessas discussões culminaram na criação de uma Taxonomia para o uso das MÃdias, além de contribuições relevantes para a criação de alguns recursos educacionais. O Grupo 2, dos professores-formadores, apoiado nos resultados do Grupo 1, tendo em vista a inclusão de alguns alunos-professores convidados, graduados e deficientes - três com surdez e dois deficientes visuais -, contribuiu para evidenciar as ações-reflexões do Design Educacional no curso escolhido, adotando uma perspectiva inclusiva, inspirada no Universal Design for Learning. O Grupo 3, de alunos-professores, avaliou as ações resultantes da pesquisa. Recorreu-se a cinco categorias de análise dos dados: o Design Educacional na instituição pesquisada; a relação entre os professores-formadores e o Design Educacional; representações sobre o processo de ensino e de aprendizagem dos profissionais envolvidos no Design Educacional; alunos-professores em formação para a Educação a Distância; as perspectivas do Design Educacional na sociedade contemporânea. Os resultados obtidos trouxeram contribuições teóricas e práticas para a formação docente, acarretando, ainda: mudanças de conduta dos Grupos 1 e 2 no planejamento e na produção de recursos educacionais; além da proposta de inclusão de uma equipe de Design Educacional junto à equipe de produção, com uma consequente melhora do trabalho colaborativo. Foi destacada, também, a necessidade de uma melhor definição das concepções e do modelo de educação a distância adotado pelo Instituto Federal do EspÃrito Santo, o que, por sua vez, impactariam no Design Educacional em uma perspectiva inclusiva
Unusual light spectra from a two-level atom in squeezed vacuum
We investigate the interaction of an atom with a multi-channel squeezed
vacuum. It turns out that the light coming out in a particular channel can have
anomalous spectral properties, among them asymmetry of the spectrum, absence of
the central peak as well as central hole burning for particular parameters. As
an example plane-wave squeezing is considered. In this case the above phenomena
can occur for the light spectra in certain directions. In the total spectrum
these phenomena are washed out.Comment: 16 pages, LaTeX, 3 figures (included via epsf
Influence of biological activity on 65Zn and 109Cd removal from tidal water by chronically-polluted mangrove sediments
The biological activity influence on the mangrove sediment capacity to remove 65Zn and 109Cd from tidal water was evaluated in a site chronically polluted. Benthic Activity Indexes (BAI), corresponding to relative estimates of biological impact on radiotracer accumulation, were higher for 109Cd (~ 38%) than for 65Zn (~ 10%) in the top centimetre of sediment. However, BAI exceeded 96% for deeper sediment layers. This apparent decrease in radiotracer diffusion into deep sediments through biological activity inhibition is stronger than reported for much less polluted mangrove nearby, suggesting that benthic organisms tolerant of chronic metal pollution may affect metal sorption mechanisms.info:eu-repo/semantics/publishedVersio
Heralded single photon absorption by a single atom
The emission and absorption of single photons by single atomic particles is a
fundamental limit of matter-light interaction, manifesting its quantum
mechanical nature. At the same time, as a controlled process it is a key
enabling tool for quantum technologies, such as quantum optical information
technology [1, 2] and quantum metrology [3, 4, 5, 6]. Controlling both emission
and absorption will allow implementing quantum networking scenarios [1, 7, 8,
9], where photonic communication of quantum information is interfaced with its
local processing in atoms. In studies of single-photon emission, recent
progress includes control of the shape, bandwidth, frequency, and polarization
of single-photon sources [10, 11, 12, 13, 14, 15, 16, 17], and the
demonstration of atom-photon entanglement [18, 19, 20]. Controlled absorption
of a single photon by a single atom is much less investigated; proposals exist
but only very preliminary steps have been taken experimentally such as
detecting the attenuation and phase shift of a weak laser beam by a single atom
[21, 22], and designing an optical system that covers a large fraction of the
full solid angle [23, 24, 25]. Here we report the interaction of single
heralded photons with a single trapped atom. We find strong correlations of the
detection of a heralding photon with a change in the quantum state of the atom
marking absorption of the quantum-correlated heralded photon. In coupling a
single absorber with a quantum light source, our experiment demonstrates
previously unexplored matter-light interaction, while opening up new avenues
towards photon-atom entanglement conversion in quantum technology.Comment: 10 pages, 4 figure
Stochastic wave function approach to the calculation of multitime correlation functions of open quantum systems
Within the framework of probability distributions on projective Hilbert space
a scheme for the calculation of multitime correlation functions is developed.
The starting point is the Markovian stochastic wave function description of an
open quantum system coupled to an environment consisting of an ensemble of
harmonic oscillators in arbitrary pure or mixed states. It is shown that matrix
elements of reduced Heisenberg picture operators and general time-ordered
correlation functions can be expressed by time-symmetric expectation values of
extended operators in a doubled Hilbert space. This representation allows the
construction of a stochastic process in the doubled Hilbert space which enables
the determination of arbitrary matrix elements and correlation functions. The
numerical efficiency of the resulting stochastic simulation algorithm is
investigated and compared with an alternative Monte Carlo wave function method
proposed first by Dalibard et al. [Phys. Rev. Lett. {\bf 68}, 580 (1992)]. By
means of a standard example the suggested algorithm is shown to be more
efficient numerically and to converge faster. Finally, some specific examples
from quantum optics are presented in order to illustrate the proposed method,
such as the coupling of a system to a vacuum, a squeezed vacuum within a finite
solid angle, and a thermal mixture of coherent states.Comment: RevTex, 19 pages, 3 figures, uses multico
Novel cyclic di-GMP effectors of the YajQ protein family control bacterial virulence
Bis-(3 ',5 ') cyclic di-guanylate (cyclic di-GMP) is a key bacterial second messenger that is implicated in the regulation of many critical processes that include motility, biofilm formation and virulence. Cyclic di-GMP influences diverse functions through interaction with a range of effectors. Our knowledge of these effectors and their different regulatory actions is far from complete, however. Here we have used an affinity pull-down assay using cyclic di-GMP-coupled magnetic beads to identify cyclic di-GMP binding proteins in the plant pathogen Xanthomonas campestris pv. campestris (Xcc). This analysis identified XC_3703, a protein of the YajQ family, as a potential cyclic di-GMP receptor. Isothermal titration calorimetry showed that the purified XC_3703 protein bound cyclic di-GMP with a high affinity (K-d similar to 2 mu M). Mutation of XC_3703 led to reduced virulence of Xcc to plants and alteration in biofilm formation. Yeast two-hybrid and far-western analyses showed that XC_3703 was able to interact with XC_2801, a transcription factor of the LysR family. Mutation of XC_2801 and XC_3703 had partially overlapping effects on the transcriptome of Xcc, and both affected virulence. Electromobility shift assays showed that XC_3703 positively affected the binding of XC_2801 to the promoters of target virulence genes, an effect that was reversed by cyclic di-GMP. Genetic and functional analysis of YajQ family members from the human pathogens Pseudomonas aeruginosa and Stenotrophomonas maltophilia showed that they also specifically bound cyclic di-GMP and contributed to virulence in model systems. The findings thus identify a new class of cyclic di-GMP effector that regulates bacterial virulence
Differential influence of vemurafenib and dabrafenib on patients' lymphocytes despite similar clinical efficacy in melanoma
In this study, we demonstrate that vemurafenib but not dabrafenib reduces peripheral lymphocyte counts in melanoma patients while both agents show similar clinical efficacy. Within the lymphocyte compartment, vemurafenib selectively decreases circulating CD4+ T cells and changes their phenotype and function. This indicates that selective BRAFi need to be assessed individually for immunomodulatory effects, especially, when planning combinations with immunotherapie
Deterministic polarization chaos from a laser diode
Fifty years after the invention of the laser diode and fourty years after the
report of the butterfly effect - i.e. the unpredictability of deterministic
chaos, it is said that a laser diode behaves like a damped nonlinear
oscillator. Hence no chaos can be generated unless with additional forcing or
parameter modulation. Here we report the first counter-example of a
free-running laser diode generating chaos. The underlying physics is a
nonlinear coupling between two elliptically polarized modes in a
vertical-cavity surface-emitting laser. We identify chaos in experimental
time-series and show theoretically the bifurcations leading to single- and
double-scroll attractors with characteristics similar to Lorenz chaos. The
reported polarization chaos resembles at first sight a noise-driven mode
hopping but shows opposite statistical properties. Our findings open up new
research areas that combine the high speed performances of microcavity lasers
with controllable and integrated sources of optical chaos.Comment: 13 pages, 5 figure
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