Collapse and revival oscillations as a probe for the tunneling amplitude in an ultra-cold Bose gas

We present a theoretical study of the quantum corrections to the revival time due to finite tunneling in the collapse and revival of matter wave interference after a quantum quench. We study hard-core bosons in a superlattice potential and the Bose-Hubbard model by means of exact numerical approaches and mean-field theory. We consider systems without and with a trapping potential present. We show that the quantum corrections to the revival time can be used to accurately determine the value of the hopping parameter in experiments with ultracold bosons in optical lattices.Comment: 10 pages, 12 figures, typos in section 3A correcte

Analysis of the optical field on the human retina from wavefront aberration data

Wave aberrations in the human eye are usually known with respect to the ideal spherical wavefront in the exit pupil. Using Kirchhoff's diffraction theory, we have derived a diffraction integral to compute the optical field on the retina from the wave aberration data. We have proposed a numerical algorithm based on the Stamnes-Spjelkavik-Pedersen (SSP) method to solve that integral. We have shown which approximations are admissible to reduce the complexity of the diffraction integral. In addition, we have compared our results with those of the conventional procedure used to compute intensities on the retina. We have found significant differences between our results and the conventional ones

Expansion of Bose-Hubbard Mott insulators in optical lattices

We study the expansion of bosonic Mott insulators in the presence of an optical lattice after switching off a confining potential. We use the Gutzwiller mean-field approximation and consider two different setups. In the first one, the expansion is restricted to one direction. We show that this leads to the emergence of two condensates with well defined momenta, and argue that such a construct can be used to create atom lasers in optical lattices. In the second setup, we study Mott insulators that are allowed to expand in all directions in the lattice. In this case, a simple condensate is seen to develop within the mean-field approximation. However, its constituent bosons are found to populate many nonzero momentum modes. An analytic understanding of both phenomena in terms of the exact dispersion relation in the hard-core limit is presented.Comment: 11 pages, 9 figures. Figures 2,3,4 correcte

Pontine calcification in late stage cerebellar multiple system atrophy: a marker of synucleinopathy neurodegeneration?

Univ Fed Sao Paulo, Dept Neurol, Unidade Ataxia, Sao Paulo, SP, BrazilHosp Israelita Albert Einstein, Sao Paulo, SP, BrazilFac Ciencias Med Santa Casa Sao Paulo, Div Radiol, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Neurol, Unidade Ataxia, Sao Paulo, SP, BrazilWeb of Scienc

Investigação geológica na porção central da estrutura de impacto meteorítico Santa Marta, Estado do Piauí, Brasil

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSanta Marta is a 10 km wide, reasonably well preserved, complex impact structure located in southwestern Piaui state, northeastern Brazil, with a central uplift of 3.2 km diameter. The Santa Marta structure was recently recognized as the sixth confirmed i474673692FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2012/50368-1, 2012/04191-2, 2012/04191-2,166948/2013-6, 305911/2013-

Non-Markovian Transmission through Two Quantum Dots Connected by a Continuum

We consider a transport setup containing a double-dot connected by a continuum. Via an exact solution of the time-dependent Schr\"odinger equation, we demonstrate a highly non-Markovian quantum-coherence-mediated transport through this dot-continuum-dot (DCD) system, which is in contrast with the common premise since in typical case a quantum particle does not reenter the system of interest once it irreversibly decayed into a continuum (such as the spontaneous emission of a photon). We also find that this DCD system supports an unusual steady state with unequal source and drain currents, owing to electrons irreversibly entering the continuum and floating there

Predictive factors for beneficial application of high-frequency electromagnetics for tumour vaporization and coagulation in neurosurgery

<p>Abstract</p> <p>Objective</p> <p>To identify preoperative and intraoperative factors and conditions that predicts the beneficial application of a high-frequency electromagnetic field (EMF) system for tumor vaporization and coagulation.</p> <p>Methods</p> <p>One hundred three subsequent patients with brain tumors were microsurgically treated using the EMF system in addition to the standard neurosurgical instrumentarium. A multivariate analysis was performed regarding the usefulness (ineffective/useful/very helpful/essential) of the new technology for tumor vaporization and coagulation, with respect to tumor histology and location, tissue consistency and texture, patients' age and sex.</p> <p>Results</p> <p>The EMF system could be used effectively during tumor surgery in 83 cases with an essential contribution to the overall success in 14 cases. In the advanced category of effectiveness (very helpful/essential), there was a significant difference between hard and soft tissue consistency (50 of 66 cases vs. 3 of 37 cases). The coagulation function worked well (very helpful/essential) for surface (73 of 103 cases) and spot (46 of 103 cases) coagulation when vessels with a diameter of less than one millimeter were involved. The light-weight bayonet hand piece and long malleable electrodes made the system especially suited for the resection of deep-seated lesions (34 of 52 cases) compared to superficial tumors (19 of 50 cases).</p> <p>The EMF system was less effective than traditional electrosurgical devices in reducing soft glial tumors. Standard methods where also required for coagulation of larger vessels.</p> <p>Conclusion</p> <p>It is possible to identify factors and conditions that predict a beneficial application of high-frequency electromagnetics for tumor vaporization and coagulation. This allows focusing the use of this technology on selective indications.</p

Host specificity versus plasticity: testing the morphology-based taxonomy of the endoparasitic copepod family Splanchnotrophidae with COI barcoding

The Splanchnotrophidae is a family of highly modified endoparasitic copepods known to infest nudibranch or sacoglossan sea slug hosts. Most splanchnotrophid species appear to be specific to a single host, but some were reported from up to nine different host species. However, splanchnotrophid taxonomy thus far is based on external morphology, and taxonomic descriptions are, mostly, old and lack detail. They are usually based on few specimens, with intraspecific variability rarely reported. The present study used molecular data for the first time to test (1) the current taxonomic hypotheses, (2) the apparently strict host specificity of the genus Ismaila and (3) the low host specificity of the genus Splanchnotrophus with regard to the potential presence of cryptic species. Phylogenetic analyses herein used sequences of the barcoding region of the cytochrome oxidase I (COI) gene from 40 specimens representing 13 species of five genera. Species delimitation approaches include distance and barcoding gap analyses, haplotype networks and diagnostic nucleotides. Molecular results are largely compatible with the commonly accepted, morphology-based taxonomy of the Splanchnotrophidae. Strict host specificity could be confirmed for two Ismaila species. COI analyses also supported the idea that Splanchnotrophus angulatus is host-promiscuous. In Ismaila, morphology seems more suitable than barcoding to display speciation events via host switches in a recent Chilean radiation. In Splanchnotrophus, some genetic structure suggests ongoing diversification, which should be investigated further given the inadequate morphology-based taxonomy. The present study thus supports the presence of two different life history strategies in splanchnotrophids, which should be explored integratively

Measuring large-scale structure with quasars in narrow-band filter surveys

We show that a large-area imaging survey using narrow-band filters could detect quasars in sufficiently high number densities, and with more than sufficient accuracy in their photometric redshifts, to turn them into suitable tracers of large-scale structure. If a narrow-band optical survey can detect objects as faint as i=23, it could reach volumetric number densities as high as 10^{-4} h^3 Mpc^{-3} (comoving) at z~1.5 . Such a catalog would lead to precision measurements of the power spectrum up to z~3-4. We also show that it is possible to employ quasars to measure baryon acoustic oscillations at high redshifts, where the uncertainties from redshift distortions and nonlinearities are much smaller than at z<1. As a concrete example we study the future impact of J-PAS, which is a narrow-band imaging survey in the optical over 1/5 of the unobscured sky with 42 filters of ~100 A full-width at half-maximum. We show that J-PAS will be able to take advantage of the broad emission lines of quasars to deliver excellent photometric redshifts, \sigma_{z}~0.002(1+z), for millions of objects.Comment: Matches version published in MNRAS (2012