9,852 research outputs found
Subsídios técnicos para a produção e comercialização de sementes certificadas do coqueiro.
Discute produção de sementes de coqueiro, auxiliando o Ministério da Agricultura e Abastecimento no processo de certificação, auxiliar os produtores de coco na aquisição de sementes de coco, auxilia no controle do comércio clandestino de sementes de coqueiro além de outras assuntos.bitstream/item/46722/1/CPATC-DOCUMENTOS-10-SUBSIDIOS-TECNICOS-PARA-A-PRODUCAO-E-COMERCIALIZACAO-DE-SEMENTES-CERTIFICADAS.pd
Comportamento de variedades de aipim no estado de Sergipe.
Dez variedades de aipim foram avaliadas quanto à produção de parte aérea, de raízes e teores de matéria seca e de amido, em diferentes épocas de colheita, em três microrregiões do estado de Sergipe, no período de 2004 a 2006, visando à recomendação daquelas mais promissoras para cultivo nessas regiões.bitstream/CPATC/19760/1/bp-20.pd
Saddles in the energy landscape probed by supercooled liquids
We numerically investigate the supercooled dynamics of two simple model
liquids exploiting the partition of the multi-dimension configuration space in
basins of attraction of the stationary points (inherent saddles) of the
potential energy surface. We find that the inherent saddles order and potential
energy are well defined functions of the temperature T. Moreover, decreasing T,
the saddle order vanishes at the same temperature (T_MCT) where the inverse
diffusivity appears to diverge as a power law. This allows a topological
interpretation of T_MCT: it marks the transition from a dynamics between basins
of saddles (T>T_MCT) to a dynamics between basins of minima (T<T_MCT).Comment: 4 pages, 3 figures, to be published on PR
The Apparent Fractal Conjecture: Scaling Features in Standard Cosmologies
This paper presents an analysis of the smoothness problem in cosmology by
focussing on the ambiguities originated in the simplifying hypotheses aimed at
observationally verifying if the large-scale distribution of galaxies is
homogeneous, and conjecturing that this distribution should follow a fractal
pattern in perturbed standard cosmologies. This is due to a geometrical effect,
appearing when certain types of average densities are calculated along the past
light cone. The paper starts reviewing the argument concerning the possibility
that the galaxy distribution follows such a scaling pattern, and the premises
behind the assumption that the spatial homogeneity of standard cosmology can be
observable. Next, it is argued that to discuss observable homogeneity one needs
to make a clear distinction between local and average relativistic densities,
and showing how the different distance definitions strongly affect them,
leading the various average densities to display asymptotically opposite
behaviours. Then the paper revisits Ribeiro's (1995: astro-ph/9910145) results,
showing that in a fully relativistic treatment some observational average
densities of the flat Friedmann model are not well defined at z ~ 0.1, implying
that at this range average densities behave in a fundamentally different manner
as compared to the linearity of the Hubble law, well valid for z < 1. This
conclusion brings into question the widespread assumption that relativistic
corrections can always be neglected at low z. It is also shown how some key
features of fractal cosmologies can be found in the Friedmann models. In view
of those findings, it is suggested that the so-called contradiction between the
cosmological principle, and the galaxy distribution forming an unlimited
fractal structure, may not exist.Comment: 30 pages, 2 figures, LaTeX. This paper is a follow-up to
gr-qc/9909093. Accepted for publication in "General Relativity and
Gravitation
Supersymmetric and Shape-Invariant Generalization for Nonresonant and Intensity-Dependent Jaynes-Cummings Systems
A class of shape-invariant bound-state problems which represent transition in
a two-level system introduced earlier are generalized to include arbitrary
energy splittings between the two levels as well as intensity-dependent
interactions. We show that the couple-channel Hamiltonians obtained correspond
to the generalizations of the nonresonant and intensity-dependent nonresonant
Jaynes-Cummings Hamiltonians, widely used in quantized theories of laser. In
this general context, we determine the eigenstates, eigenvalues, the time
evolution matrix and the population inversion matrix factor.Comment: A combined version of quant-ph/0005045 and quant-ph/0005046. 24
pages, LATE
Enraizamento ex vitro da cultivar de mamona BRS nordestina a partir de brotos micropropagados in vitro.
bitstream/CNPA/19672/1/COMTEC250.pd
Efeito do tiadiazuron na micropropagação in vitro de dois genótipos de mamona via organogênese.
Made available in DSpace on 2011-07-08T01:02:43Z (GMT). No. of bitstreams: 1
v14n04a04.pdf: 165472 bytes, checksum: 0047e6041416c36dce88495e7b726d38 (MD5)
Previous issue date: 2010-04-13201
Entangled-Photon Imaging of a Pure Phase Object
We demonstrate experimentally and theoretically that a coherent image of a
pure phase object may be obtained by use of a spatially incoherent illumination
beam. This is accomplished by employing a two-beam source of entangled photons
generated by spontaneous parametric down-conversion. Though each of the beams
is, in and of itself, spatially incoherent, the pair of beams exhibits
higher-order inter-beam coherence. One of the beams probes the phase object
while the other is scanned. The image is recorded by measuring the photon
coincidence rate using a photon-counting detector in each beam. Using a
reflection configuration, we successfully imaged a phase object implemented by
a MEMS micro-mirror array. The experimental results are in accord with
theoretical predictions.Comment: 11 pages, 3 figures, submittedto Phys. Rev. Let
Green's Function for Nonlocal Potentials
The single-particle nuclear potential is intrinsically nonlocal. In this
paper, we consider nonlocalities which arise from the many-body and fermionic
nature of the nucleus. We investigate the effects of nonlocality in the nuclear
potential by developing the Green's function for nonlocal potentials. The
formal Green's function integral is solved analytically in two different limits
of the wavelength as compared to the scale of nonlocality. Both results are
studied in a quasi-free limit. The results illuminate some of the basic effects
of nonlocality in the nuclear medium.Comment: Accepted for publication in J. Phys.
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