We quantize the recent hydrodynamic analysis of Stringari for the low-energy collective modes of a trapped Bose gas at T = 0. This is based on the timedependent Gross-Pitaevskii equation, but omits the kinetic energy of the density fluctuations. We diagonalize the hydrodynamic Hamiltonian in terms of the normal modes associated with the amplitude and phase of the inhomogeneous Bose order parame...

Primordial fluctuations in the cosmic density are usually assumed to take the form of a Gaussian random field that evolves under the action of gravitational instability. In the early stages, while they have low amplitude, the fluctuations grow linearly. During this phase the Gaussian character of the fluctuations is preserved. Later on, when the fluctuations have amplitude of order the mean den...

a frequency-wavenumber-domain formulation is presented in this paper for calculation of the green's functions and wave propagation modes in a stratified fluid body underlain by a layered viscoelastic soil medium. the green's functions define the solid and fluid displacements and fluid pressures due to uniform disk loads acting in either the soil or fluid media. the solution is in the frequency ...

This paper deals with the representation of the trace of iterative Schwarz solutions at the interfaces of domain decomposition to approximate adaptively the interface error operator. This allows to build a cost-effectively accelerating of the convergence of the iterative method by extending to the vectorial case the Aitken’s accelerating convergence technique. The first representation is based ...

We study the dynamics of thermally excited capillary waves (CW) at molecular scales, using molecular dynamics simulations of simple liquid slabs. The analysis is based on the Fourier modes of the liquid surface, constructed via the intrinsic sampling method (Chacón and Tarazona 2003 Phys. Rev. Lett. 91 166103). We obtain the time autocorrelation of the Fourier modes to get the frequency and dam...

The depth of field of real/virtual and focused mode in three-dimensional integral imaging is taken into account by using the Fourier optics approach and considering the effects of diffraction and defocus aberration. The concepts of point spread function and optical transfer function are applied to three-dimensional integral imaging system and used to investigate the depth of field for both modes.

The vibrational spectra (Raman, photoacoustic and Fourier transform infrared and inelastic neutron scattering) of the calcium, strontium and europium salts of hexahydrido- and hexadeuteridoruthenate(II) have been analyzed. All observed fundamental modes and overtone and combination bands are assigned. Density functional theory calculations of the vibrational frequencies assist in the analysis.

A Bruker model IFS 125HR Fourier transform interferometer has been installed and its performance tested using high-brightness, far-infrared synchrotron radiation. Results of absorption measurements for the rotational modes of water vapor demonstrate a nearly 10-fold improvement in signal-to-noise when compared with the instrument’s internal high-pressure Hg arc lamp source. 2008 Published by El...

In this paper we present improved upper bounds on the number of determining Fourier modes, determining nodes and volume elements for the Navier-Stokes equations. The bounds presented here seem to agree with some of the heuristic physical estimates conjectured by Manley and Treve.

In this paper, Langevin model equation is proposed for Fourier modes of velocity field of isotropic turbulence whose statistical properties are identical to those governed by equations of Self-Consistent-Field (SCF) theory of turbulence [J. R. Herring, Physics of Fluids 9, 2106 (1966)].