601 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.
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
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Gradients in compositions in the starchy endosperm of wheat have implications for milling and processing
Background: Wheat is the major food grain consumed in temperate countries. Most wheat is consumed after
milling to produce white flour, which corresponds to the endosperm storage tissue of the grain. Because the
starchy endosperm accounts for about 80% of the grain dry weight, the miller aims to achieve flour yields
approaching this value.
Scope and approach: Bioimaging can be combined with biochemical analysis of fractions produced by sequential
pearling of whole grains to determine the distributions of components within the endosperm tissue.
Key findings and conclusions: This reveals that endosperm is not homogeneous, but exhibits gradients in composition
from the outer to the inner part. These include gradients in both amount and composition. For example,
the content of gluten proteins decreases but the proportion of glutenin polymers increases from the outside to the
centre of the tissue. However, the content of starch increases with changes in the granule size distribution, the
proportions of amylose and amylopectin, and their thermal properties. Hence these parts of the endosperm differ
in the functional properties for food processing. Gradients also exist in minor components which may affect
health and processing, such as dietary fibre and lipids. The gradients in grain composition are reflected in
differences in the compositions of the mill streams which are combined to give white flour (which may number
over 20). These differences could therefore be exploited by millers and food processors to develop flours with
compositions and properties for specific end uses
Dark Energy in an Axion Model with Explicit Z(N) Symmetry Breaking
We point out that a well known axion model with an explicit Z(N) symmetry
breaking term predicts both dark energy and cold dark matter. We estimate the
parameters of this model which fit the observed densities of the dark
components of the universe. We find that the parameters do not conflict with
any observations.Comment: 5 pages, minor change
Nuevas citas de Eleutherodactylus Duméril y Bibron, 1841 (Anura, Leptodactylidae) para Bolivia
Five species of the genus Eleutherodactylus (Anura, Leptodactylidae) are reported from Bolivia for the first time: E. altamazonicus from Departments Pando and La Paz; E. carvalhoi from Cochabamba; and E. ockendeni, E. skydmainos and E. zimmermanae from Pando. New departmental records are provided for other species: E. cruralis for Department Pando, E. danae for Beni and La Paz, E. platydactylus for Beni, E. toftae for Pando and La Paz and E. ventrimarmoratus for La Paz. Currently, 25 species of Eleutherodactylus are known in Bolivia. The taxonomic status of some species remains uncertain, new species are being described and others are still to be discovered. Therefore, the actual number of Bolivian Eleutherodactylus species is still unknown.En este trabajo se publican los primeros registros de cinco especies del género Eleutherodactylus (Anura, Leptodactylidae) para Bolivia: E. altamazonicus en los Departamentos de Pando y La Paz; E. carvalhoi en Cochabamba; y E. ockendeni, E. skydmainos y E. zimmermanae en Pando. Además, se aportan las primeras citas de E. cruralis para el Departamento de Pando, de E. danae para Beni y La Paz, de E. platydactylus para Beni, de E. toftae para Pando y La Paz y de E. ventrimarmoratus para La Paz. La diversidad conocida de Eleutherodactylus en Bolivia es de 25 especies, aunque los problemas taxonómicos sin resolver, las especies en descripción y el alto número de especies aún no citadas que se considera probable encontrar, hacen que aún desconozcamos la verdadera diversidad de este género en Bolivia
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