scholarly journals Self-consistent microscopic description of neutron scattering by16O based on the continuum particle-vibration coupling method

2012 ◽  
Vol 86 (4) ◽  
Author(s):  
Kazuhito Mizuyama ◽  
Kazuyuki Ogata
Keyword(s):  
Neutron Scattering ◽  
Coupling Method ◽  
Microscopic Description ◽  
Self Consistent ◽  
Vibration Coupling ◽  
The Continuum

scholarly journals Josephson oscillations in split one-dimensional Bose gases

2021 ◽  
Vol 10 (4) ◽  
Author(s):  
Yuri Daniel van Nieuwkerk ◽  
Jörg Schmiedmayer ◽  
Fabian Essler
Keyword(s):  
Three Dimensional ◽  
Time Dependent ◽  
Dimensional Theory ◽  
Bose Gases ◽  
Microscopic Description ◽  
One Dimensional ◽  
Hartree Fock ◽  
Equilibrium Dynamics ◽  
Self Consistent ◽  
Double Well Potential

We consider the non-equilibrium dynamics of a weakly interacting Bose gas tightly confined to a highly elongated double well potential. We use a self-consistent time-dependent Hartree--Fock approximation in combination with a projection of the full three-dimensional theory to several coupled one-dimensional channels. This allows us to model the time-dependent splitting and phase imprinting of a gas initially confined to a single quasi one-dimensional potential well and obtain a microscopic description of the ensuing damped Josephson oscillations.

scholarly journals Evolution and State of the Local ISM

1996 ◽  
Vol 171 ◽  
pp. 442-442
Author(s):  
T. Schmutzler ◽  
D. Breitschwerdt
Keyword(s):  
Basic Feature ◽  
Emission Lines ◽  
Continuum Emission ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Self Consistent ◽  
X Ray Background ◽  
Collisional Ionization ◽  
Consistent Approach ◽  
The Continuum

The most puzzling observations concerning the LISM (distance < 100 pc) can be explained by a fast adiabatically cooled gas in the cavity of an old superbubble. The ultrasoft X-ray background and contributions to the C- and M-bands are due to the continuum emission of delayed recombination [1]. In contrast to collisional ionization equilibrium (CIE) models, but consistent with recent observations [2], our model predicts a lack of emission lines and a low emissivity in the EUV range. In the figure below we compare the emissivities resulting from CIE at T = 106 K and those from our model at T = 4.2 × 104 K. The basic feature of our model is a thermally self-consistent approach of the time-dependent evolution.

scholarly journals Implementation of a self-consistent slab model of bilayer structure in the SasView suite

2021 ◽  
Vol 54 (1) ◽  
pp. 363-370
Author(s):  
Luoxi Tan ◽  
James G. Elkins ◽  
Brian H. Davison ◽  
Elizabeth G. Kelley ◽  
Jonathan Nickels
Keyword(s):  
Neutron Scattering ◽  
Lipid Bilayers ◽  
Scattering Length ◽  
Solvent Molecule ◽  
Scattering Data ◽  
Bilayer Structure ◽  
Slab Model ◽  
Scattering Length Density ◽  
Self Consistent ◽  
Solvent Molecules

Slab models are simple and useful structural descriptions which have long been used to describe lyotropic lamellar phases, such as lipid bilayers. Typically, slab models assume a midline symmetry and break a bilayer structure into three pieces, a central solvent-free core and two symmetric outer layers composed of the soluble portion of the amphiphile and associated solvent. This breakdown matches reasonably well to the distribution of neutron scattering length density and therefore is a convenient and common approach for the treatment of small-angle scattering data. Here, an implementation of this model within the SasView software suite is reported. The implementation is intended to provide physical consistency through the area per amphiphile molecule and number of solvent molecules included within the solvent-exposed outer layer. The proper use of this model requires knowledge of (or good estimates for) the amphiphile and solvent molecule volume and atomic composition, ultimately providing a self-consistent data treatment with only two free parameters: the lateral area per amphiphile molecule and the number of solvent molecules included in the outer region per amphiphile molecule. The use of this code is demonstrated in the fitting of standard lipid bilayer data sets, obtaining structural parameters consistent with prior literature and illustrating the typical and ideal cases of fitting for neutron scattering data obtained using single or multiple contrast conditions. While demonstrated here for lipid bilayers, this model is intended for general application to block copolymers, surfactants, and other lyotropic lamellar phase structures for which a slab model is able to reasonably estimate the neutron scattering length density/electron-density profile of inner and outer layers of the lamellae.

Falling plumes in bacterial bioconvection

2001 ◽  
Vol 445 ◽  
pp. 121-149 ◽  
Author(s):  
AISLING M. METCALFE ◽  
T. J. PEDLEY
Keyword(s):  
Boundary Layer ◽  
Bacillus Subtilis ◽  
Theoretical Model ◽  
Two Dimensional ◽  
Volume Flux ◽  
Self Consistent ◽  
Consistent Solution ◽  
Continuum Description ◽  
Upper Boundary ◽  
The Continuum

Experiments by Kessler on bioconvection in laboratory suspensions of bacteria (Bacillus subtilis), contained in a deep chamber, reveal the development of a thin upper boundary layer of cell-rich fluid which becomes unstable, leading to the formation of falling plumes. We use the continuum description of such a suspension developed by Hillesdon et al. (1995) as the basis for a theoretical model of the boundary layer and an axisymmetric plume. If the boundary layer has dimensionless thickness λ [Lt ] 1, the plume has width λ1/2. A similarity solution is found for the plume in which the cell flux and volume flux can be matched to those in the boundary layer and in the bulk of the suspension outside both regions. The corresponding model for a two-dimensional plume fails to give a self-consistent solution.

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