Unconventional Hall effect near charge neutrality point in a two-dimensional electron-hole system

The transport properties of the two-dimensional system in HgTe-based quantum wells containing simultaneously electrons and holes of low densities are examined. The Hall resistance, as a function of perpendicular magnetic field, reveals an unconventional behavior, different from the classical N-shaped dependence typical for bipolar systems with electron-hole asymmetry. The quantum features of magnetotransport are explained by means of numerical calculation of the Landau level spectrum based on the Kane Hamiltonian. The origin of the quantum Hall plateau sigma(xy) = 0 near the charge neutrality point is attributed to special features of Landau quantization in our system.

Portal de Busca Integrada

O SIBiUSP lançou em março de 2012 uma nova ferramenta de busca de conteúdos acadêmicos/científicos, o nome dado foi Portal de Busca Integrada. Esta ferramenta pertence à uma categoria de softwares intitulada de “Web Scale Discovery”, que permitem a integração de diversas e dispersas fontes de dados em uma única interface de busca e entrega de resultados. Dessa forma, apresentam-se aqui os processos de seleção e implantação desta solução.

Whole-body MRI: comprehensive evaluation on a 48-channel 3T MRI system in less than 40 minutes. Preliminary results

OBJECTIVE: To evaluate a comprehensive MRI protocol that investigates for cancer, vascular disease, and degenerative/inflammatory disease from the head to the pelvis in less than 40 minutes on a new generation 48-channel 3T system. MATERIALS AND METHODS: All MR studies were performed on a 48-channel 3T MR scanner. A 20-channel head/neck coil, two 18-channel body arrays, and a 32-channel spine array were employed. A total of 4 healthy individuals were studied. The designed protocol included a combination of single-shot T2-weighted sequences, T1-weighted 3D gradient-echo pre- and post-gadolinium. All images were retrospectively evaluated by two radiologists independently for overall image quality. RESULTS: The image quality for cancer was rated as excellent in the liver, pancreas, kidneys, lungs, pelvic organs, and brain, and rated as fair in the colon and breast. For vascular diseases ratings were excellent in the aorta, major branch vessel origins, inferior vena cava, portal and hepatic veins, rated as good in pulmonary arteries, and as poor in the coronary arteries. For degenerative/inflammatory diseases ratings were excellent in the brain, liver and pancreas. The inter-observer agreement was excellent. CONCLUSION: A comprehensive and time efficient screening for important categories of disease processes may be achieved with high quality imaging in a new generation 48-channel 3T system.

Portal de Busca Integrada do SIBiUSP: metodologia de implantação

Relata o estudo, a instalação e implantação de ferramenta de descoberta e entrega do Portal de Busca Integrada, para o Sistema Integrado de Bibliotecas da Universidade de São Paulo (SIBiUSP). Esta nova interface denominada Portal de Busca Integrada possibilita uma nova experiência de pesquisa científica ao usuário final pela recuperação de literatura em diferentes fontes de informação.