819 research outputs found
Refractive effects in the scattering of loosely bound nuclei
A study of the interaction of loosely bound nuclei 6,7Li at 9 and 19 AMeV
with light targets has been undertaken. With the determination of unambiguous
optical potentials in mind, elastic data for four projectile-target
combinations and one neutron transfer reaction 13C(7Li,8Li)12C have been
measured on a large angular range. The kinematical regime encompasses a region
where the mean field (optical potential) has a marked variation with mass and
energy, but turns out to be sufficiently surface transparent to allow strong
refractive effects to be manifested in elastic scattering data at intermediate
angles. The identified exotic feature, a "plateau" in the angular distributions
at intermediate angles, is fully confirmed in four reaction channels and
interpreted as a pre-rainbow oscillation resulting from the interference of the
barrier and internal barrier farside scattering subamplitudes.Comment: 19 pages, 14 figures, 3 tables to submit to Phys. Rev.
Towards first-principles based kinetic modeling of biomass fast pyrolysis
Biomass conversion to chemicals and fuels through fast pyrolysis shows great potential but requires a more fundamental approach for its deployment. To this end, molecular-based kinetic modeling is starting to play a central role in the prediction of the molecular composition of bio-oil. A molecular-level representation of biomass provides the start point for the generation of detailed pyrolysis reaction networks for both the condensed and the gas phases. Significant progress has been made for cellulose, glucose-based carbohydrates, and lignin, together with the incorporation of the catalytic effects of minerals. Ab initio techniques are widely used to discriminate between reaction mechanisms and to calculate kinetic parameters. Automatic kinetic model generation is expected to play an even more important role in fast pyrolysis as it does already today. Experimental techniques enabled to obtain intrinsic kinetics and to decouple the timescales between reaction kinetics and analytic techniques. This greatly benefits the improvement of detailed kinetic models. The prospects for achieving a first-principles based kinetic model of biomass fast pyrolysis are promising. However, significant work is still needed to couple condensed- and gas-phase reaction networks
Coherent states for the q-deformed quantum mechanics on a circle
The q-deformed coherent states for a quantum particle on a circle are
introduced and their properties investigated.Comment: 11 pages, 2 PostScript figure
Comment on "On the uncertainty relations and squeezed states for the quantum mechanics on a circle"
It is shown by examples that the position uncertainty on a circle, proposed
recently by Kowalski and Rembieli\'nski [J. Phys. A 35 (2002) 1405] is not
consistent with the state localization. We argue that the relevant
uncertainties and uncertainty relations (UR's) on a circle are that based on
the Gram-Robertson matrix. Several of these generalized UR's are displayed and
related criterions for squeezed states are discussed.Comment: 5 pages, LaTex2e, 3 figures.ep
The Influence of Age, Live Weight and Gender on the Morphometrical Aspects of the Goat Brain During the Early Postnatal Development
Coherent states of a charged particle in a uniform magnetic field
The coherent states are constructed for a charged particle in a uniform
magnetic field based on coherent states for the circular motion which have
recently been introduced by the authors.Comment: 2 eps figure
Human immunodeficiency virus type 1 recombinant B/G subtypes circulating in Coimbra, Portugal.
An increasing prevalence of HIV-1 non-B variants is being noticed in several European regions, particularly in countries such as Portugal, which have closer contacts with African endemic areas, where multiple HIV subtypes cocirculate. HIV-1 subtyping by phylogenetic analyses of reverse transcriptase, protease and env (C2-V3) genomic regions was carried out in plasma collected from 18 HIV-1-infected subjects living in Coimbra, Portugal, and suspected to be infected with non-B variants. Three (16.7%) subjects carried recombinant B/G viruses (BV3/BRT/Gpro; GV3/URT/Bpro; AV3/GRT/Bpro), whereas all the remaining individuals were infected with HIV-1 subtype B. This is the first report of recombinant B/G subtypes in Portugal
Coherent states for a particle on a sphere
The coherent states for a particle on a sphere are introduced. These states
are labelled by points of the classical phase space, that is the position on
the sphere and the angular momentum of a particle. As with the coherent states
for a particle on a circle discussed in Kowalski K {\em et al} 1996 {\em J.
Phys. A} {\bf 29} 4149, we deal with a deformation of the classical phase space
related with quantum fluctuations. The expectation values of the position and
the angular momentum in the coherent states are regarded as the best possible
approximation of the classical phase space. The correctness of the introduced
coherent states is illustrated by an example of the rotator.Comment: LaTeX, 16 pages, 2 figure
Produccion de semillas en yacon (Smallanthus sonchifolius (Poepp. & Endl.)) mediante tecnicas de polinizacion controladas.
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