Boojums in Rotating Two-Component Bose-Einstein Condensates

A boojum is a topological defect that can form only on the surface of an ordered medium such as superfluid $^3$He and liquid crystals. We study theoretically boojums appearing between two phases with different vortex structures in two-component BECs where the intracomponent interaction is repulsive in one phase and attractive in the other. The detailed structure of the boojums is revealed by investigating its density distribution, effective superflow vorticity and pseudospin texture.Comment: 4 pages, 4 figure

Vortex Lattice Structures of a Bose-Einstein Condensate in a Rotating Lattice Potential

We study vortex lattice structures of a trapped Bose-Einstein condensate in a rotating lattice potential by numerically solving the time-dependent Gross-Pitaevskii equation. By rotating the lattice potential, we observe the transition from the Abrikosov vortex lattice to the pinned lattice. We investigate the transition of the vortex lattice structure by changing conditions such as angular velocity, intensity, and lattice constant of the rotating lattice potential.Comment: 6 pages, 8 figures, submitted to Quantum Fluids and Solids Conference (QFS 2006

Anti-thyroid antibodies: methodological aspects and diagnostic significance

Since the first publication, more than 40 years ago, laboratory tests for the presence of antibodies (Ab) to thyroid antigens (Ag) have played a pivotal position in the diagnosis of thyroid diseases. Thyroid is a common target for autoimmune diseases, hence the interest in the definition of the thyroid Ag that could be involved in the process. The first Ag to be recognized was thyroglobulin, followed by the microsomal Ag, later identified with thyroid peroxidase, the TSH receptor and, more recently, other Ag like the sodium/iodide symporter (NIS). The methodologies employed evolved from the initial hemaglutination assays, to the present use of recombinant Ag, alternative labels and transfected cells. Today the clinical uses of a test to detect the presence of Ab against thyroid Ag are very well defined. The most useful test is the detection of anti-peroxidase Ab, the test with greatest sensitivity and specificity for the presence of autoimmune thyroid diseases. The anti-thyroglobulin test is mandatory as a complement for the measurement of thyroglobulin in the follow-up of patients with differentiated thyroid cancers. The anti-TSH receptor test has its main use in the definition of the presence of Graves disease. Tests for the presence of Ab against other thyroid Ag have no clear indication at the moment. The continuous methodological developments will certainly increase the utility of tests for anti-thyroid Ab.Desde sua descrição, há mais de 40 anos, a pesquisa de anticorpos (Ac) contra antígenos (Ag) tiroideanos tem tido papel importante no diagnóstico da patologia tiroideana. A tiróide é freqüentemente acometida por doenças autoimunes, daí o interesse pela definição dos Ag tiroideanos que podem estar envolvidos no processo. O primeiro Ag reconhecido foi a tireoglobulina, seguido do fator microssomal, mais tarde identificado como a peroxidase tiroideana, o receptor de TSH e mais recentemente outros Ag como o cotransportador de sódio e iodo (sodium/iodide symporter, NIS). As metodologias evoluíram dos ensaios iniciais por hemaglutinação até o emprego atual de Ag recombinantes, marcadores alternativos e células transfectadas. Atualmente as indicações clínicas da pesquisa de Ac anti-tiroideanos são bem definidas, sendo o de maior aplicação a pesquisa de Ac anti-peroxidase, que é o que apresenta maior especificidade e sensibilidade para a definição da presença de doença autoimune tiroideana. A pesquisa de Ac anti-tireoglobulina é fundamental como complemento da dosagem de tireoglobulina no acompanhamento de pacientes com carcinoma diferenciado de tiróide. Já a pesquisa de Ac anti-receptor de TSH tem indicação precisa na definição da presença de doença de Graves. As indicações de pesquisa de Ac contra outros Ag tiroideanos não têm, atualmente, indicações comprovadas. A contínua evolução metodológica deverá aumentar ainda mais as indicações e utilidades da pesquisa de Ac contra Ag tiroideanos.Universidade Federal de São Paulo (UNIFESP) EPM Departamento de MedicinaUNIFESP, EPM, Depto. de MedicinaSciEL

Dynamic optical lattices: two-dimensional rotating and accordion lattices for ultracold atoms

We demonstrate a novel experimental arrangement which rotates a 2D optical lattice at frequencies up to several kilohertz. Ultracold atoms in such a rotating lattice can be used for the direct quantum simulation of strongly correlated systems under large effective magnetic fields, allowing investigation of phenomena such as the fractional quantum Hall effect. Our arrangement also allows the periodicity of a 2D optical lattice to be varied dynamically, producing a 2D accordion lattice.Comment: 7 pages, 5 figures, final versio

Route to turbulence in a trapped Bose-Einstein condensate

We have studied a Bose-Einstein condensate of $^{87}Rb$ atoms under an oscillatory excitation. For a fixed frequency of excitation, we have explored how the values of amplitude and time of excitation must be combined in order to produce quantum turbulence in the condensate. Depending on the combination of these parameters different behaviors are observed in the sample. For the lowest values of time and amplitude of excitation, we observe a bending of the main axis of the cloud. Increasing the amplitude of excitation we observe an increasing number of vortices. The vortex state can evolve into the turbulent regime if the parameters of excitation are driven up to a certain set of combinations. If the value of the parameters of these combinations is exceeded, all vorticity disappears and the condensate enters into a different regime which we have identified as the granular phase. Our results are summarized in a diagram of amplitude versus time of excitation in which the different structures can be identified. We also present numerical simulations of the Gross-Pitaevskii equation which support our observations.Comment: 6 pages, 3 figure

Development of a semi-automated method for measuring urinary iodine and its application in epidemiological studies in Brazilian schoolchildren

In this study we developed a semi-automated method for the measurement of urinary iodine using firstly ammonium persulfate for digestion of urine followed by estimation of iodine content in the Sandell-Kolthoff reaction, in which iodine acts as a catalyst for the reduction of cerium. This method was validated in the 3rd Brazilian National Survey of iodine deficiency in 1994. We studied 16,803 casual urine samples from schoolchildren of 401 cities and found 4 moderately-deficient towns (Almas, Arraias, and Parana, in the State of Tocantins, and Cocos, in the State of Bahia), and 116 mildly-deficient. This work suggests that despite the salt iodization program, there was some iodine-deficient areas in Brazil in 1994. Recent surveys, involving less cities, are indicating an excess of iodine ingestion. Therefore, in a country of continental dimensions and very heterogeneous in terms of public health, periodical evaluations are necessary to monitor the real situation of iodine nutrition in Brazil. the method developed in this paper is suitable for these surveys.Univ Estadual Maringa, Dept Med, Ctr Ciencias Saude, Maringa, Parana, BrazilUniversidade Federal de São Paulo, Mol Endocrinol Lab, Disciplina Endocrinol, Dept Med,Escola Paulista Med, BR-04032029 São Paulo, BrazilUniversidade Federal de São Paulo, Mol Endocrinol Lab, Disciplina Endocrinol, Dept Med,Escola Paulista Med, BR-04032029 São Paulo, BrazilWeb of Scienc

Experimental findings of soil particle movement in 2D seepage failure of soil using Particle Image Velocimetry

Seepage failure is one of the most important issues associated with the performance-based design of soil at high groundwater sites. We discuss the movement of soil particles with increase in the hydraulic head difference, H, in half 2D model tests on the seepage failure of soil in front of sheet piles using PIV analyses (Particle Image Velocimetry). The following conclusions were obtained: (1) At a certain value of Hpiv lower than Hy, the micro movement of soil particles is found around the bottom tip of a sheet pile wall, where Hpiv and Hy are the hydraulic head differences at the start of soil particle movement using PIV analysis, and at the onset of deformation of the soil surface, respectively. (2) The location of the micro movement of soil particles corresponds reasonably well with the net < 0 region, where net is the net body force exerted on a unit volume of soil. (3) Micro movement of soil particles occurs at a hydraulic head difference of 73 - 100% of Hy. (4) PIV analyses show the boundaries between regions where soil particles do or do not move as well as the movement of sand particles. (5) The region of soil particle movement proves the validity of the prism of failure for Terzaghi’s method and the prismatic failure concept