Probing the energy bands of a Bose-Einstein condensate in an optical lattice

We simulate several methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained by the different methods agree within the accuracy of the simulation. The meaning of the results in terms of density and phase deformations is tested by studying the relaxation of a phase-modulated condensate toward the ground state

Ground state of trapped interacting Bose-Einstein condensates by an explicit imaginary-time algorithm

We show that an explicit time-marching method previously developed for the numerical study of the dynamics of Bose-Einstein condensates can be profitably adapted to the numerical determination of their ground state. After reduction to a one-dimensional model, we first reproduce and test known results on condensates in harmonic traps and then determine the ground state of a condensate in a harmonically bound optical lattice in the range of parameters which are relevant to existing experiments

Hydrodynamic excitations in a spin-polarized Fermi gas under harmonic confinement in one dimension

We consider a time-dependent nonlinear Schrodinger equation in one dimension (1D) with a fifth-order interaction term and external harmonic confinement, as a model for both (i) a Bose gas with hard-core contact interactions in the local-density approximation, and (ii) a spin-polarized Fermi gas in the collisional regime. We evaluate analytically in the Thomas-Fermi limit the density fluctuation profiles and the collective excitation frequencies, and compare the results for the low-lying modes with those obtained from numerical solution of the Schrodinger equation. We find that the excitation frequencies are multiples of the harmonic-trap frequency even in the strong-coupling Thomas-Fermi regime. This result shows that the hydrodynamic and the collisionless collective spectra coincide in the harmonically confined 1D Fermi gas, as they do for sound waves in its homogeneous analog. It also shows that in this case the local-density theory reproduces the exact collective spectrum of the hard-core Bose gas under harmonic confinement

Numerical solution of the Gross-Pitaevskii equation using an explicit finite-difference scheme: An application to trapped Bose-Einstein condensates

A fast, explicit time-marching scheme is used for the solution of the Gross-Pitaevskii equation in cylindrical geometry. Scheme validity is analyzed using simple analytical tests and is demonstrated for two situations of physical interest on the Bose-Einstein condensation (BEC) of trapped alkali-metal vapors. This is tested using reproduced results on the free expansion of a BEC after removing a cylindrical trap

HR-MAS NMR spectroscopy in the characterization of human tissues: Application to healthy gastric mucosa

The HR-MAS is an ideal technique for the investigation of intact tissue specimens (10-50 mg) and permits the obtainment of spectra with a resolution comparable to that observed in solution in a time that does not exceed a half of an hour for a routine analysis. The potentialities of HR-MAS NMR spectroscopy in the identification of the metabolites characterizing the healthy gastric mucosa are here presented. The direct 1D H-1 NMR spectra enables only few metabolites to be confidently assigned, and the use of selected 2D experiments strongly amplify the analytical effectiveness of the technique

In vitro antimicrobial activity of essential oils against salmonella enterica serotypes enteritidis and typhimurium strains isolated from poultry

Salmonella enterica serotype Enteritidis and S. enterica serotype Typhimurium are frequently present among poultry and are associated with outbreaks of human salmonellosis. The study investigated the in vitro antimicrobial activity of essential oils (EOs) obtained from Aloysia triphylla, Cinnamomum zeylanicum, Cymbopogon citratus, Litsea cubeba, Mentha piperita, Syzygium aromaticum against S. Enteritidis and S. Thyphimurium strains previously isolated from poultry. A 1:1 mixture of C. zeylanicum and S. aromaticum was also tested. The activity of all compounds was evaluated against the yeast Saccharomyces cerevisiae, commonly used as probiotic. The highest antibacterial activity was observed for C. zeylanicum (minimum inhibitory concentrations (MICs) ranging from 1.26 mg/mL to 0.63 mg/mL), S. aromaticum (MICs from 2.637 mg/mL to 0.164 mg/mL) and the mixture (MICs from 1.289 mg/mL to 0.322 mg/mL). No activity was recorded against S. cerevisiae. The results suggest a possible use of C. zeylanicum and S. aromaticum, alone or in combination, in the farm environment for disinfection and in poultry diet, combined with S. cerevisiae administration, for an integrated approach to avoid Salmonella intestinal colonization

Molecular characterization of human gastric mucosa by HR-MAS Magnetic Resonance Spectroscopy

The present study was aimed at identifying themolecular profile characteristic of the healthy humangastric mucosa.Ex vivo HR-MAS magnetic resonance spectroscopy performed at 9.4 Tesla (400.13 MHz for 1H) on gastric specimens collected during endoscopy, permits the identification of more than forty species giving a detailed picture of the biochemical pattern of the gastric tissues. These preliminary data will be used for a comparison with gastric preneoplastic and neoplastic situations. Moreover, the full knowledge of the biochemical pattern of the healthy gastrictissues is the necessary presupposition for the application of magnetic resonance spectroscopy directly in vivo

Superfluid and dissipative dynamics of a Bose-Einstein condensate in a periodic optical potential

We create Bose-Einstein condensates of Rb-87 in a static magnetic trap with a superimposed blue-detuned 1D optical lattice. By displacing the magnetic trap center we are able to control the condensate evolution. We observe a change in the frequency of the center-of-mass oscillation in the harmonic trapping potential, in analogy with an increase in effective mass. For fluid velocities greater than a local speed of sound, we observe the onset of dissipative processes up to full removal of the superfluid component. A parallel simulation study visualizes the dynamics of the Bose-Einstein condensate and accounts for the main features of the observed behavior