Vortices and turbulence in trapped atomic condensates

After over a decade of experiments generating and studying the physics of quantized vortices in atomic gas Bose-Einstein condensates, research is beginning to focus on the roles of vortices in quantum turbulence, as well as other measures of quantum turbulence in atomic condensates. Such research directions have the potential to uncover new insights into quantum turbulence, vortices and superfluidity, and also explore the similarities and differences between quantum and classical turbulence in entirely new settings. Here we present a critical assessment of theoretical and experimental studies in this emerging field of quantum turbulence in atomic condensates

Simple analysis of off-axis solenoid fields using the scalar magnetostatic potential: application to a Zeeman-slower for cold atoms

In a region free of currents, magnetostatics can be described by the Laplace equation of a scalar magnetic potential, and one can apply the same methods commonly used in electrostatics. Here we show how to calculate the general vector field inside a real (finite) solenoid, using only the magnitude of the field along the symmetry axis. Our method does not require integration or knowledge of the current distribution, and is presented through practical examples, including a non-uniform finite solenoid used to produce cold atomic beams via laser cooling. These examples allow educators to discuss the non-trivial calculation of fields off-axis using concepts familiar to most students, while offering the opportunity to introduce important advancements of current modern research.Comment: 6 pages. Accepted in the American Journal of Physic

Bose-Einstein Condensation on Curved Manifolds

Here we describe a weakly interacting Bose gas on a curved manifold, which is embedded in the three-dimensional Euclidean space.~To this end we start by considering a harmonic trap in the normal direction of the manifold, which confines the three-dimensional Bose gas in the vicinity of its surface.~Following the notion of dimensional reduction as outlined in [L.~Salasnich et al., Phys.~Rev.~A {\bf 65}, 043614 (2002)], we assume a large enough trap frequency so that the normal degree of freedom of the condensate wave function can be approximately integrated out. In this way we obtain an effective condensate wave function on the quasi-two-dimensional surface of the curved manifold, where the thickness of the cloud is determined self-consistently. For the particular case when the manifold is a sphere, our equilibrium results show how the chemical potential and the thickness of the cloud increase with the interaction strength.~Furthermore, we determine within a linear stability analysis the low-lying collective excitations together with their eigenfrequencies, which turn out to reveal an instability for attractive interactions.Comment: 33 pages, 6 figure

Uma abordagem pontual acerca da Cultura e do Direito no Rio de Janeiro contemporâneo

O trabalho tem como cenário a cidade do Rio de Janeiro no período compreendido entre os anos de 1945/1964. A abordagem em si discute, de maneira geral, a convivência sócio institucional urbana pós segunda guerra mundial, envolvendo, de maneira particular, a cultura urbana prevalente nos aspectos político, jurídico e social. Discute de maneira bem pontual, as novas idealizações civilizatórias projetadas para o Brasil tendo como referência a nova ordem ocidental pós-moderna, principalmente naquilo que envolve os contextos político, econômico e social. No aspecto político, aborda o mosaico político-partidário daépoca e, principalmente, a Constituição Federal de 1946. No aspecto econômico, aborda a inserção do Brasil à nova ordem imposta pelo neo-capitalismo mundial, basicamente aquele oriundo do capital expansionista americano. No aspecto social, o texto observa o comportamento social, os costumes impactados pela nova mentalidade emergente. Dentro da perspectiva jurídica, o trabalho observa também a promulgação dos direitos sociais, dos direitos políticos e a idealização pela afirmação da cidadania como pressuposto obrigatório na reforma política empreendida no período

Análogo mecânico para a condutividade elétrica dos metais : efeitos da temperatura

Electrical conductivity is one of the most important concepts within aspects of modern physics with a great extension to materials science. It is responsible for most applications of metallic and semiconductor materials. The understanding of microscopic models that reproduce certain characteristics is an important step towards the understanding of materials. In this work we continue to use a system that constitutes a mechanical analogue to understand how the limitations of electrical conductivity of metals occur. Using this model we investigated the effect of temperature on conductivity. The model presented here is quite instructive and lends itself very well to demonstrations in the classroom or even for carrying out laboratory practices in undergraduate courses or teaching practices in Physics in High School

Single nucleotide polymorphisms from Theobroma cacao expressed sequence tags associated with witches' broom disease in cacao

In order to increase the efficiency of cacao tree resistance to witches¿ broom disease, which is caused by Moniliophthora perniciosa (Tricholomataceae), we looked for molecular markers that could help in the selection of resistant cacao genotypes. Among the different markers useful for developing marker-assisted selection, single nucleotide polymorphisms (SNPs) constitute the most common type of sequence difference between alleles and can be easily detected by in silico analysis from expressed sequence tag libraries. We report the first detection and analysis of SNPs from cacao-M. perniciosa interaction expressed sequence tags, using bioinformatics. Selection based on analysis of these SNPs should be useful for developing cacao varieties resistant to this devastating disease. (Résumé d'auteur