1,152 research outputs found
Mean-Field Approximation to the Master Equation for Sympathetic Cooling of Trapped Bosons
We use the mean-field approximation to simplify the master equation for
sympathetic cooling of Bosons. For the mean single-particle occupation numbers,
this approach yields the same equations as the factorization assumption
introduced in an erlier paper. The stationary or equilibrium solution of the
resulting master equation for the one-body density matrix shows that the
mean-field approximation breaks down whenever the fraction of condensate Bosons
exceeds ten percent or so of the total. Using group-theoretical methods, we
also solve the time-dependent master equation for the one-body density matrix.
Given the time dependence of the mean single-particle occupation numbers, this
solution is obtained by quadratures. It tends asymptotically towards the
equilibrium solution.Comment: submitted to PR
Dimer states in atomic mixtures
A mixture of heavy atoms in a Mott state and light spin-1/2 fermionic atoms
is studied in an optical lattice. Inelastic scattering processes between both
atomic species excite the heavy atoms and renormalize the tunneling rate as
well as the interaction of the light atoms. An effective Hamiltonian for the
latter is derived that describes tunneling of single fermions, tunneling of
fermionic pairs and an exchange of fermionic spins. Low energy states of this
Hamiltonian are a N\'eel state for strong effective repulsion, dimer states for
moderate interaction, and a density wave of paired fermions for strong
effective attraction.Comment: 10 pages, 3 figure, extended versio
Main characteristics and genesis of the Vale de Pães skarn (Cuba-Vidigueira, Ossa Morena Zone, Portugal)
The Vale de Pães (Cuba-Vidigueira) mineralisation is composed of magnetite ± sulphides and hosted
in a Pre-Variscan metamorphic sequence intruded by igneous rocks belonging to the Beja Igneous Complex.
Its mineral and chemical features are compatible with a zoned Fe-skarn: Mg-rich (Fo + Di90, oxidised)
and Ca-rich (Grs + Di81-39, oxidised or relatively reduced). In the Fe-Mg skarn, magnetite deposition
occurred along with the anhydrous mineral assemblage at ≈ 600 °C; sulphides precipitated from the
retrograde stage onset (≤ 550 °C) and during the hydrated and carbonate phases formation period
(< 420 °C). In the Fe-Ca skarn, magnetite precipitated during the retrograde stage (< 550 °C) together
with the hydrated mineral association, and was followed by sulphides at ≈ 400°C. The mineralising
process involved moderate-high salinity fluids and was controlled by variations in redox potential and pH.info:eu-repo/semantics/publishedVersio
Principales características y génesis del skarn de Vale de Pães (Cuba-Vidigueira, Ossa Morena Zone, Portugal)
The Vale de Pães (Cuba-Vidigueira) mineralisation is composed of magnetite ± sulphides and hosted in a Pre-Variscan metamorphic sequence intruded by igneous rocks belonging to the Beja Igneous Complex. Its mineral and chemical features are compatible with a zoned Fe-skarn: Mg-rich (Fo + Di90, oxidised) and Ca-rich (Grs + Di81-39, oxidised or relatively reduced). In the Fe-Mg skarn, magnetite deposition occurred along with the anhydrous mineral assemblage at ≈ 600 °C; sulphides precipitated from the retrograde stage onset (≤ 550 °C) and during the hydrated and carbonate phases formation period (< 420 °C). In the Fe-Ca skarn, magnetite precipitated during the retrograde stage (< 550 °C) together with the hydrated mineral association, and was followed by sulphides at ≈ 400°C. The mineralising process involved moderate-high salinity fluids and was controlled by variations in redox potential and pH.La mineralización del Vale de Pães (Cuba-Vidigueira), compuesta de magnetita ± sulfuros, se produce dentro de una secuencia metamórfica ante-Varisca intruida por el Complejo Ígneo de Beja (Beja Igneous Complex). Sus características químicas y mineralógicas son consistentes con un skarn de Fe zonificado: rico en Mg (Fo + Di≈90, oxidado) y rico en Ca (Grs + Di81-39, oxidado o relativamente reducido). En el skarn de Fe-Mg, la deposición de magnetita acompaña a la paragénesis mineral anhidra (≈ 600 °C); la precipitación de sulfuros se produce desde el comienzo de la etapa retrógrada (≤ 550 °C) y continuó durante la formación de fases hidratadas y carbonatadas (< 420 °C). En el skarn de Fe-Ca, la magnetita se genera en la fase de retroceso (< 550 °C), en relación con la asociación de minerales hidratados, seguido de sulfuro (≈ 400 °C). El proceso de mineralización de los fluidos de salinidad moderada-alta era controlado por los cambios en el potencial redox y el pH
Spatial optical solitons supported by mutual focusing
We study composite spatial optical solitons supported by two-wave mutual
focusing induced by cross-phase modulation in Kerr-like nonlinear media. We
find the families of both single- and two-hump solitons and discuss their
properties and stability. We also reveal remarkable similarities between
recently predicted holographic solitons in photorefractive media and parametric
solitons in quadratic nonlinear crystals.Comment: 3 pages, 3 figure
Remembering Parotitis in SARS-CoV-2 era
New 2019-Coronavirus (SARS-CoV-2) pandemic is presenting daily diagnostic challenges to emergency departments (ED) doctors, especially as an
increasing number of atypical clinical presentations have been reported, including acute sialadenitis (most of parotid).
We present a case of a 46-year-old obese caucasian woman, with no relevant medical history, that presented in ED with complaints suggesting parotitis,
with normal laboratory tests, at first with no virus isolation, confirmed by computed tomography. One week later, anosmia and dysgeusia were notice, and
SARS-CoV-2 was tested and confirmed.
Authors want to alert that SARS-CoV-2 should be excluded as parotitis etiology, highly important, especially in this pandemic phase, as a way of transmission controinfo:eu-repo/semantics/publishedVersio
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