Boson-fermion mixtures inside an elongated cigar-shaped trap

We present mean-field calculations of the equilibrium state in a gaseous mixture of bosonic and spin-polarized fermionic atoms with repulsive or attractive interspecies interactions, confined inside a cigar-shaped trap under conditions such that the radial thickness of the two atomic clouds is approaching the magnitude of the s-wave scattering lengths. In this regime the kinetic pressure of the fermionic component is dominant. Full demixing under repulsive boson-fermion interactions can occur only when the number of fermions in the trap is below a threshold, and collapse under attractive interactions is suppressed within the range of validity of the mean-field model. Specific numerical illustrations are given for values of system parameters obtaining in 7Li-6Li clouds.Comment: 12 pages, 6 figure

Renormalization Group Analysis of a Gursey Model Inspired Field Theory II

Recently a model, which is equivalent to the scalar form of Gursey model, is shown to be a nontrivial field theoretical model when it is gauged with a SU(N) field. In this paper we study another model that is equivalent to the vector form of the Gursey model. We get a trivial theory when it is coupled with a scalar field. This result changes drastically when it is coupled with an additional SU(N) field. We find a nontrivial field theoretical model under certain conditions.Comment: 10 pages, 10 figures, revtex4, typos corrected, published versio

On the performance of West's bubble test: A simulation approach

Cataloged from PDF version of article.In this research we examine the ability of West’s bubble test [1] in detecting speculative bubbles using Brock’s (1982) [2] intertemporal general equilibrium model of asset pricing as the basis for a simulation study. In this setting, (1) the economy, by construction is effi- cient and produces the maximally possible amount of welfare for society, and (2) asset prices reflect the utility-maximizing behavior of consumers and the profit-maximizing behavior of firms. We find that the West’s bubble test flag as ‘‘bubbles” in the simulated data yet the data is produced from an economy in which markets are efficient in welfare production

Phase separation in a boson-fermion mixture of Lithium atoms

We use a semiclassical three-fluid model to analyze the conditions for spatial phase separation in a mixture of fermionic Li-6 and a (stable) Bose-Einstein condensate of Li-7 atoms under cylindrical harmonic confinement, both at zero and finite temperature. We show that with the parameters of the Paris experiment [F. Schrek et al., Phys. Rev. Lett. 87 080403 (2001)] an increase of the boson-fermion scattering length by a factor five would be sufficient to enter the phase-separated regime. We give examples of configurations for the density profiles in phase separation and estimate that the transition should persist at temperatures typical of current experiments. For higher values of the boson-fermion coupling we also find a new phase separation between the fermions and the bosonic thermal cloud at finite temperature.Comment: 8 pages, 4 figures, new version of Fig. 4 and typos correcte

Immunohistochemical evaluation of iron accumulation in term placenta of preeclamptic patients

Preeclampsia is a disease which involves hypertension and multisystem, it effects approximately 2 to 8% of all pregnancies and is a significant cause of maternal and newborn mortality and morbidity. It develops in the placenta and its pathogenesis is associated with placental abnormalities. Classical immunohistochemical studies on placenta have shown that there is a linear increase in iron storage in the placenta in the first half of a normal pregnancy, however, these stocks are decreased in normal 3rd trimester placenta. Iron accumulation in term placentas of preeclamptic and normal pregnancies were evaluated in this study. Ferritin immunostaining was observed to be more intense in preeclamptic group than in the control group, especially in Hofbauer cells, subtrophoblastic areas of stem villous, perivasculer stroma and villous stroma. Statistical analysis of the data was performed using SPSS software. Mann Whitney U test was used in the analysis and P values below 0.05 were statistically significant. In this study, iron accumulations in normotensif and preeclamptic placentas werecompared.Key words: Preeclampsia, placenta, immunohistochemistry, iron accumulation

Diffusiophoretic Behavior of Polyelectrolyte-Coated Particles

Diffusiophoresis, the movement of particles under a solute concentration gradient, has practical implications in a number of applications, such as particle sorting, focusing, and sensing. For diffusiophoresis in an electrolyte solution, the particle velocity is described by the electrolyte relative concentration gradient and the diffusiophoretic mobility of the particle. The electrolyte concentration, which typically varies throughout the system in space and time, can also influence the zeta potential of particles in space and time. This variation affects the diffusiophoretic behavior, especially when the zeta potential is highly dependent on the electrolyte concentration. In this work, we show that adsorbing a single bilayer (or 4 bilayers) of a polyelectrolyte pair (PDADMAC/PSS) on the surface of microparticles resulted in effectively constant zeta potential values with respect to salt concentration throughout the experimental range of salt concentrations. This allowed a constant potential model for diffusiophoretic transport to describe the experimental observations, which was not the case for uncoated particles in the same electrolyte system. This work highlights the use of simple polyelectrolyte pairs to tune the zeta potential and maintain constant values for precise control of diffusiophoretic transport

Collective excitations of a trapped boson-fermion mixture across demixing

We calculate the spectrum of low-lying collective excitations in a mesoscopic cloud formed by a Bose-Einstein condensate and a spin-polarized Fermi gas as a function of the boson-fermion repulsions. The cloud is under isotropic harmonic confinement and its dynamics is treated in the collisional regime by using the equations of generalized hydrodynamics with inclusion of surface effects. For large numbers of bosons we find that, as the cloud moves towards spatial separation (demixing) with increasing boson-fermion coupling, the frequencies of a set of collective modes show a softening followed by a sharp upturn. This behavior permits a clear identification of the quantum phase transition. We propose a physical interpretation for the dynamical transition point in a confined mixture, leading to a simple analytical expression for its location.Comment: revtex4, 9 pages, 8 postscript file