123 research outputs found
Avaliação de impactos econômicos pela adoção de processo automatizado de gestão de bibliotecas utilizando o software Ainfo.
Nesse estudo foi avaliado o ganho econômico que a Embrapa obteve na utilização de um sistema informatizado para gestão de bibliotecas, desenvolvido pela própria instituição e adotado desde 1991. Para tanto, foram subtraídos os gastos (incorridos no desenvolvimento, manutenção e utilização do sistema) das receitas, entendidas como as economias geradas a partir das mudanças nos processos com a adoção do software Ainfo.Sober 2014
Relatório de avaliação dos impactos do sistema para automação de bibliotecas e recuperação da informação (Ainfo).
Em 1991, com a popularização de ferramentas digitais, a Empresa Brasileira de Pesquisa Agropecuária (Embrapa) lança a primeira versão de um sistema que visava integrar todas as suas bibliotecas, aumentando a sua capacidade de organização, armazenamento e disponibilização do conhecimento gerado. Denominado de Sistema para Automação de Bibliotecas e Recuperação da Informação (Ainfo), essa tecnologia constitui-se atualmente num importante elo entre a produção científica da Embrapa e os seus mais variados usuários, por meio do acesso gratuito a milhares de obras disponíveis tanto em suas bibliotecas, quanto em sites criados a partir dessa grande base de dados. Esse estudo foi conduzido com o propósito de se estimar os ganhos econômicos, sociais, ambientais e de desenvolvimento institucional do Ainfo, utilizando-se de metodologia preconizada pela Embrapa e parte integrante do Balanço Social da Empresa
Ultrafast Laser-Induced Melting of Long-Range Magnetic Order in Multiferroic TbMnO3
We performed ultrafast time-resolved near-infrared pump, resonant soft X-ray
diffraction probe measurements to investigate the coupling between the
photoexcited electronic system and the spin cycloid magnetic order in
multiferroic TbMnO3 at low temperatures. We observe melting of the long range
antiferromagnetic order at low excitation fluences with a decay time constant
of 22.3 +- 1.1 ps, which is much slower than the ~1 ps melting times previously
observed in other systems. To explain the data we propose a simple model of the
melting process where the pump laser pulse directly excites the electronic
system, which then leads to an increase in the effective temperature of the
spin system via a slower relaxation mechanism. Despite this apparent increase
in the effective spin temperature, we do not observe changes in the wavevector
q of the antiferromagnetic spin order that would typically correlate with an
increase in temperature under equilibrium conditions. We suggest that this
behavior results from the extremely low magnon group velocity that hinders a
change in the spin-spiral wavevector on these time scales.Comment: 9 pages, 4 figure
Alien Registration- Breton, Honore (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/30621/thumbnail.jp
Strong Influence of Coadsorbate Interaction on CO Desorption Dynamics on Ru(0001) Probed by Ultrafast X-Ray Spectroscopy and \u3cem\u3eAb Initio\u3c/em\u3e Simulations
We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5σ and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process
Spatially resolved ultrafast magnetic dynamics launched at a complex-oxide hetero-interface
Static strain in complex oxide heterostructures has been extensively used to
engineer electronic and magnetic properties at equilibrium. In the same spirit,
deformations of the crystal lattice with light may be used to achieve
functional control across hetero-interfaces dynamically. Here, by exciting
large amplitude infrared-active vibrations in a LaAlO3 substrate we induce
magnetic order melting in a NdNiO3 film across a hetero-interface. Femtosecond
Resonant Soft X-ray Diffraction is used to determine the spatial and temporal
evolution of the magnetic disordering. We observe a magnetic melt front that
grows from the substrate interface into the film, at a speed that suggests
electronically driven propagation. Light control and ultrafast phase front
propagation at hetero-interfaces may lead to new opportunities in
optomagnetism, for example by driving domain wall motion to transport
information across suitably designed devices.Comment: 35 pages, 8 Figures (both incl. Supplement
Light-enhanced Charge Density Wave Coherence in a High-Temperature Superconductor
In high-T cuprates, superconductivity and charge density waves (CDW)
are competitive, yet coexisting orders. To understand their microscopic
interdependence a probe capable of discerning their interaction on its natural
length and time scales is necessary. Here we use ultrafast resonant soft x-ray
scattering to track the transient evolution of CDW correlations in
YBaCuO following the quench of superconductivity by an
infrared laser pulse. We observe a picosecond non-thermal response of the CDW
order, characterized by a large enhancement of spatial coherence, nearly
doubling the CDW correlation length, while only marginally affecting its
amplitude. This ultrafast snapshot of the interaction between order parameters
demonstrates that their competition manifests inhomogeneously through
disruption of spatial coherence, and indicates the role of superconductivity in
stabilizing topological defects within CDW domains.Comment: 29 pages, 9 figures, Main text and Supplementary Material
The Present Habitability Potential of Gale Crater: What We Have Learned So Far From Mars Science Laboratory
The Mars Science Laboratory mission has comprehensively interrogated the surface environment of Mars as it explores Gale Crater. Both chemical and physical attributes of the present environment have been measured over the course of the mission, enabling us to compare the present state of the martian surface with the environmental requirements of prokaryotic microbes. While this approach does not exclude the possibility of martian life that may have evolved to adapt to the present conditions, it is advantageous in that it allows us to evaluate environmental requirements of known life and also provide insight into the likelihood of forward contamination by Earth organisms with the comparison of their environmental requirements with the measured attributes of the environment at Gale Crater. We have already modeled a paleoenvironment with high habitability potential (HP) based upon chemistry, mineralogy and other geological evidence such as sedimentary structures and larger scale geomorphology [1]. In this report, we turn our attention to the present HP of the Yellowknife Bay area, including the importance of the physical environmental metrics such as atmospheric pressure, air and ground temperature, ionizing radiation, wind speed and direction, slope, etc
Enhanced charge density wave coherence in a light-quenched, high-temperature superconductor
Superconductivity and charge density waves (CDWs) are competitive, yet coexisting, orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning their interaction on its natural length and time scale is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution of CDW correlations in YBa2Cu3O6+x after the quench of superconductivity by an infrared laser pulse. We observe a nonthermal response of the CDW order characterized by a near doubling of the correlation length within ≈1 picosecond of the superconducting quench. Our results are consistent with a model in which the interaction between superconductivity and CDWs manifests inhomogeneously through disruption of spatial coherence, with superconductivity playing the dominant role in stabilizing CDW topological defects, such as discommensurations
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