Investigations on finite ideal quantum gases

Recursion formulae of the N-particle partition function, the occupation numbers and its fluctuations are given using the single-particle partition function. Exact results are presented for fermions and bosons in a common one-dimensional harmonic oscillator potential, for the three-dimensional harmonic oscillator approximations are tested. Applications to excited nuclei and Bose-Einstein condensation are discussed.Comment: 13 pages, 7 postscript figures, uses 'epsfig.sty'. Submitted to Physica A. More information available at http://obelix.physik.uni-osnabrueck.de/~schnack

Thermodynamic fermion-boson symmetry in harmonic oscillator potentials

A remarkable thermodynamic fermion-boson symmetry is found for the canonical ensemble of ideal quantum gases in harmonic oscillator potentials of odd dimensions. The bosonic partition function is related to the fermionic one extended to negative temperatures, and vice versa.Comment: 7 pages, no figures, submitted to PHYSICA A. More information available at http://www.physik.uni-osnabrueck.de/makrosysteme

The effect of various dietary factores on the serum- cholesterol level

No Abstract

Determining Shear Wave Velocities in Soft Marine Sediments

The inversion technique presented in this volume (Cheng, 1987) that simultaneously inverts full waveform acoustic logs for shear wave velocity (V[subscript 3]) and compressional wave attenuation (Q[subscript p]) was applied to selected full waveform acoustic logs taken in soft sediments from Deep Sea Drilling Project Site 613. Besides V[subscript 3] and Q[subscript p], the sensitivity of the inversion to perturbations in the fixed parameters, P-wave velocity (V[subscript p]), fluid velocity (V[[subscript f]), borehole diameter, bulk density (P[subscript b]), and borehole fluid attenuation (Q[subscript f]), were tested. Our study shows that the inversion technique is most sensitive to the estimate of V[subscript p] because the inversion is based on the P leaky mode energy portion of the spectrum. The Poisson's ratio, however, which primarily controls the amplitude of the waveforms, is rather stable with different estimates in V[subscript p]. The inversion technique is less sensitive to small perturbations in borehole diameter, P[subscript b], V[subscript f], and Q[subscript f] The shear wave velocities inferred from these inversions correlate well with the attendant velocity logs run at Site 613 and the diagenetic changes identified by shipboard stratigraphers. For example, there is an increase in both V[subscript p] and V[subscript 3] at the diagenetic boundary between siliceous nannofossil oozes and porcellanite. This boundary is responsible for a sharp seismic reflector in a USGS. seismic line run nearby. Over the depth interval that we analyzed, from 390.0 to 582.0 meters below sea floor, we determined shear wave velocities ranging from 0.74 to 1.06 km/sec corresponding to compressional wave velocities from 1.70 to 2.20 km/sec.Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumNational Science Foundation (U.S.) (Grant OCE84-08761)Chevron (Fellowship

Evaluation And Prediction Of Shear Wave Velocities In Soft Marine Sediments

Shear wave velocities from full waveform acoustic logs were determined at DSDP Site 613 using the spectral ratio inversion method. Discrete shear wave velocities for a 350 meter interval at 0.5-2 meter depth increments were calculated. Shear wave velocities were not evaluated for the upper 130m of the log because of data recording problems. The sediments of Site 613 represent a progression from carbonaceous-siliceous oozes through partial lithification and cementation. A method for predicting shear wave velocities using Wood's equation, the bulk moduli of water and carbonate grains, the P-wave velocity and porosity from well logs will be described. The predictions of this method provided a theoretical maximum value for the shear wave velocity to compare with the inversion results. In general, the method works well for shear wave velocities greater than 800 m/s. The inverted data fall just below the predicted theoretical maximum value from Wood's equation and agree quite well with the trends. Below this velocity threshold, trends with depth and Poisson's ratio and the divergence of the inversion itself seem to indicate incorrect behavior.Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumNational Science Foundation (U.S.) (Grant OCE84-08761)National Science Foundation (U.S.) (Grant OCE87-10226)National Science Foundation (U.S.) (Grant OCE87-20032

Quantized Roentgen Effect in Bose-Einstein Condensates

A classical dielectric moving in a charged capacitor can create a magnetic field (Roentgen effect). A quantum dielectric, however, will not produce a magnetization, except at vortices. The magnetic field outside the quantum dielectric appears as the field of quantized monopoles

Mesoscopic Fermi gas in a harmonic trap

We study the thermodynamical properties of a mesoscopic Fermi gas in view of recent possibilities to trap ultracold atoms in a harmonic potential. We focus on the effects of shell closure for finite small atom numbers. The dependence of the chemical potential, the specific heat and the density distribution on particle number and temperature is obtained. Isotropic and anisotropic traps are compared. Possibilities of experimental observations are discussed.Comment: 8 pages, 9 eps-figures included, Revtex, submitted to Phys. Rev. A, minor changes to figures and captions, corrected typo

Local/Non-Local Complementarity in Topological Effects

In certain topological effects the accumulation of a quantum phase shift is accompanied by a local observable effect. We show that such effects manifest a complementarity between non-local and local attributes of the topology, which is reminiscent but yet different from the usual wave-particle complementarity. This complementarity is not a consequence of non-commutativity, rather it is due to the non-canonical nature of the observables. We suggest that a local/non-local complementarity is a general feature of topological effects that are ``dual'' to the AB effect.Comment: 4 page

Post deposition annealing of epitaxial Ce1-xPrxO2-δ films grown on Si(111)

In this work the structural and morphological changes of Ce1−xPrxO2−δ (x = 0.20, 0.35 and 0.75) films grown on Si(111) due to post deposition annealing are investigated by low energy electron diffraction combined with a spot profile analysis. The surface of the oxide films exhibit mosaics with large terraces separated by monoatomic steps. It is shown that the Ce/Pr ratio and post deposition annealing temperature can be used to tune the mosaic spread, terrace size and step height of the grains. The morphological changes are accompanied by a phase transition from a fluorite type lattice to a bixbyite structure. Furthermore, at high PDA temperatures a silicate formation via a polycrystalline intermediate state is observed

Aharonov-Bohm scattering of charged particles and neutral atoms: the role of absorption

The Aharonov-Bohm scattering of charged particles by the magnetic field of an infinitely long and infinitely thin solenoid (magnetic string) in an absorbing medium is studied. We discuss the partial-wave approach to this problem and show that standard partial-wave method can be adjusted to this case. The effect of absorption leads to oscillations of the AB cross section. Based on this we investigate the scattering of neutral atoms with induced electric dipole moments by a charge wire of finite radius which is placed in an uniform magnetic field. The physical realistic and practically important case that all atoms which collide with the wire are totally absorbed at its surface, is studied in detail. The dominating terms of the scattering amplitude are evaluated analytically for different physical constellations. The rest terms are written in a form suitable for a numerical computation. We show that if the magnetic field is absent, the absorbing charged wire causes oscillations of the cross section. In the presence of the magnetic field the cross section increases and the dominating Aharonov--Bohm peak appears in the forward direction, suppressing the oscillations.Comment: 15 pages, LaTeXfile, 2 figure