11,922 research outputs found
Collision-Dependent Atom Tunnelling Rate in Bose-Einstein Condensates
We show that the interaction (cross-collision) between atoms trapped in
distinct sites of a double-well potential can significantly increase the atom
tunneling rate for special trap configurations leading to an effective linear
Rabi regime of population oscillation between the trap wells. The inclusion of
cross-collisional effects significantly extends the validity of the two-mode
model approach allowing it to be alternatively employed to explain the recently
observed increase of tunneling rates due to nonlinear interactions.Comment: 4 pages, 2 figures. Replaced with improved versio
On the nature of the spin-polarized hole states in a quasi-two-dimensional GaMnAs ferromagnetic layer
A self-consistent calculation of the density of states and the spectral
density function is performed in a two-dimensional spin-polarized hole system
based on a multiple-scattering approximation. Using parameters corresponding to
GaMnAs thin layers, a wide range of Mn concentrations and hole densities have
been explored to understand the nature, localized or extended, of the
spin-polarized holes at the Fermi level for several values of the average
magnetization of the Mn ystem. We show that, for a certain interval of Mn and
hole densities, an increase on the magnetic order of the Mn ions come together
with a change of the nature of the states at the Fermi level. This fact
provides a delocalization of spin-polarized extended states anti-aligned to the
average Mn magnetization, and a higher spin-polarization of the hole gas. These
results are consistent with the occurrence of ferromagnetism with relatively
high transition temperatures observed in some thin film samples and
multilayered structures of this material.Comment: 3 page
Optimal Conditions for Atomic Homodyne Detection on Bose-Einstein Condensates
The dynamics of a two-mode Bose-Einstein condensate trapped in a double-well
potential results approximately in an effective Rabi oscillation regime of
exchange of population between both wells for sufficiently strong overlap
between the modes functions. Facing this system as a temporal atomic beam
splitter we show that this regime is optimal for a nondestructive atom-number
measurement allowing an atomic homodyne detection, thus yielding indirect
relative phase information about one of the two-mode condensates.Comment: 9 pages, 5 figure
Magnetic ordering in GaAlAs:Mn double well structure
The magnetic order in the diluted magnetic semiconductor barrier of double
AlAs/GaAs: Mn quantum well structures is investigated by Monte Carlo
simulations. A confinement adapted RKKY mechanism is implemented for indirect
exchange between Mn ions mediated by holes. It is shown that, depending on the
barrier width and the hole concentration a ferromagnetic or a spin-glass order
can be established.Comment: 3 figure
Spin-polarized transport in ferromagnetic multilayered semiconductor nanostructures
The occurrence of inhomogeneous spin-density distribution in multilayered
ferromagnetic diluted magnetic semiconductor nanostructures leads to strong
dependence of the spin-polarized transport properties on these systems. The
spin-dependent mobility, conductivity and resistivity in
(Ga,Mn)As/GaAs,(Ga,Mn)N/GaN, and (Si,Mn)/Si multilayers are calculated as a
function of temperature, scaled by the average magnetization of the diluted
magnetic semiconductor layers. An increase of the resistivity near the
transition temperature is obtained. We observed that the spin-polarized
transport properties changes strongly among the three materials.Comment: 3 pages, 4 figure
Mapeamento de solos do municĂpio de Aceguá, utilizando os mĂ©todos convencionais e geotecnologias.
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Neonatal Infant Pain Scale: Cross-Cultural Adaptation and Validation in Brazil
Context: The Neonatal Infant Pain Scale (NIPS), initially developed in Canada, has been previously used but not adequately adapted and validated for use in Brazil.
Objectives: The goal of the present study was to perform a cross-cultural adaptation and clinical validation of the NIPS for use in the Brazilian population.
Methods: The instrument was adapted based on the method outlined by Beaton et al., including the production and combination of translated versions, back-translation, committee review, and pilot testing. The psychometric properties of the adapted instrument, including its validity, reliability, and internal consistency, were tested in a clinical validation study. The sample comprised 60 at-term newborns who were evaluated by six nurses as they experienced vaccination. Psychometric properties were evaluated using Student's t-tests, prevalence-adjusted and bias-adjusted kappa scores, the Bland-Altman method, and Cronbach's alpha coefficients.
Results: The Brazilian version of the NIPS (Escala de Dor no Recém-Nascido [NIPS-Brazil]) demonstrated excellent interobserver and intraobserver reliability. Total NIPS-Brazil scores yielded prevalence-adjusted and bias-adjusted kappa scores of 0.93, whereas the Bland-Altman method revealed interobserver and intraobserver reliability values of 95% and 90%, respectively. The NIPS-Brazil had adequate internal consistency, as evidenced by a Cronbach's alpha of 0.762.
Conclusion: The NIPS was successfully adapted for use in Brazil and is now available for use in the assessment of acute pain in at-term newborns in Brazil
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