339 research outputs found
Allometric growth patterns in hatchery-reared larvae of the catfish Lophiosilurus alexandri (Pisces: Pseudopimelodidae)
The aim of the present study was to characterize the relationships that occur between morphometric variables of larvae of Lophiosilurus alexandri Steindachner, 1876 through their allometric growth analysis. Total length, head length and body height were correlated with standard length, head height and body height, as well as eye diameter and head height with head length. The results revealed allometric positive relation during the initial development, where the b coefficient varied between 1.10 and 2.81. The variable pre-anal distance in relation to the standard length and the snout length in relation to the head length revealed an allometric negative relation, where the b coefficient was 0.85 and 0.94, respectively
Coulomb and nuclear breakup effects in the single neutron removal reaction 197Au(17C,16C gamma)X
We analyze the recently obtained new data on the partial cross sections and
parallel momentum distributions for transitions to ground as well as excited
states of the 16C core, in the one-neutron removal reaction 197Au(17C,16C
gamma)X at the beam energy of 61 MeV/nucleon. The Coulomb and nuclear breakup
components of the one-neutron removal cross sections have been calculated
within a finite range distorted wave Born approximation theory and an eikonal
model, respectively. The nuclear contributions dominate the partial cross
sections for the core excited states. By adding the nuclear and Coulomb cross
sections together, a reasonable agreement is obtained with the data for these
states. The shapes of the experimental parallel momentum distributions of the
core states are described well by the theory.Comment: Revtex format, two figures included, to appear in Phys. Rev. C.
(Rapid communications
Uso de hipoclorito de sódio para acelerar a emergência das plântulas e o desenvolvimento das mudas de cafeeiro
Breakup reaction models for two- and three-cluster projectiles
Breakup reactions are one of the main tools for the study of exotic nuclei,
and in particular of their continuum. In order to get valuable information from
measurements, a precise reaction model coupled to a fair description of the
projectile is needed. We assume that the projectile initially possesses a
cluster structure, which is revealed by the dissociation process. This
structure is described by a few-body Hamiltonian involving effective forces
between the clusters. Within this assumption, we review various reaction
models. In semiclassical models, the projectile-target relative motion is
described by a classical trajectory and the reaction properties are deduced by
solving a time-dependent Schroedinger equation. We then describe the principle
and variants of the eikonal approximation: the dynamical eikonal approximation,
the standard eikonal approximation, and a corrected version avoiding Coulomb
divergence. Finally, we present the continuum-discretized coupled-channel
method (CDCC), in which the Schroedinger equation is solved with the projectile
continuum approximated by square-integrable states. These models are first
illustrated by applications to two-cluster projectiles for studies of nuclei
far from stability and of reactions useful in astrophysics. Recent extensions
to three-cluster projectiles, like two-neutron halo nuclei, are then presented
and discussed. We end this review with some views of the future in
breakup-reaction theory.Comment: Will constitute a chapter of "Clusters in Nuclei - Vol.2." to be
published as a volume of "Lecture Notes in Physics" (Springer
Recipientes e substratos na produção de mudas e no desenvolvimento inicial de cafeeiros após o plantio
Fauna of mosquitoes (Diptera: Culicidae) in Goytacazes National Forest and surrounding area, State of Espírito Santo, Southeastern Brazil
Molecular epidemiology and extended-spectrum β-lactamases production of Klebsiella pneumoniae isolated from three dairy herds
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