2,695 research outputs found
Relative phase fluctuations of two coupled one-dimensional condensates
We study the relative phase fluctuations of two one-dimensional condensates coupled along their whole extension with a local single-atom interaction. The thermal equilibrium is defined by the competition between independent longitudinal thermally excited phase fluctuations and the coupling between the condensates which locally favors identical phase. We compute the relative phase fluctuations and their correlation length as a function of the temperature and the strength of the coupling
Development of a Mobile Teaching and Learning Module for VM893 (Field Services) with
The goal of this project is to develop a teaching and learning module with interactive comprehension assessments that can be used in a mobile (truck) or stationary (classroom) environment. A considerable portion of the Field Services clinical rotation is spent with students driving from the UT Veterinary Medical Center and from farm to farm in a large four-door truck. During these trips a consistent set of relevant topics will be delivered to students by discussing clinical cases. The format will be interactive and students will be equipped with technology allowing an assessment of their comprehension. Students will have day-to-day access to data collected during their assessments. Easy access to evaluations during the course could improve comprehension of the material. Moreover, the quality of teaching may improve as faculty can more easily determine if the materials they are delivering are understood, allowing adjustments to be made when necessary
Downwelled longwave surface irradiance data from five sites for the FIRE/SRB Wisconsin Experiment from October 12 through November 2, 1986
Tables are presented which show data from five sites in the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE)/Surface Radiation Budget (SRB) Wisconsin experiment regional from October 12 through November 2, 1986. A discussion of intercomparison results is also included. The field experiment was conducted for the purposes of both intensive cirrus-cloud measurements and SRB algorithm validation activities
Directional genetic differentiation and asymmetric migration
Understanding the population structure and patterns of gene flow within
species is of fundamental importance to the study of evolution. In the fields
of population and evolutionary genetics, measures of genetic differentiation
are commonly used to gather this information. One potential caveat is that
these measures assume gene flow to be symmetric. However, asymmetric gene flow
is common in nature, especially in systems driven by physical processes such as
wind or water currents. Since information about levels of asymmetric gene flow
among populations is essential for the correct interpretation of the
distribution of contemporary genetic diversity within species, this should not
be overlooked. To obtain information on asymmetric migration patterns from
genetic data, complex models based on maximum likelihood or Bayesian approaches
generally need to be employed, often at great computational cost. Here, a new
simpler and more efficient approach for understanding gene flow patterns is
presented. This approach allows the estimation of directional components of
genetic divergence between pairs of populations at low computational effort,
using any of the classical or modern measures of genetic differentiation. These
directional measures of genetic differentiation can further be used to
calculate directional relative migration and to detect asymmetries in gene flow
patterns. This can be done in a user-friendly web application called
divMigrate-online introduced in this paper. Using simulated data sets with
known gene flow regimes, we demonstrate that the method is capable of resolving
complex migration patterns under a range of study designs.Comment: 25 pages, 8 (+3) figures, 1 tabl
Creation of collective many-body states and single photons from two-dimensional Rydberg lattice gases
The creation of collective many-body quantum states from a two-dimensional
lattice gas of atoms is studied. Our approach relies on the van-der-Waals
interaction that is present between alkali metal atoms when laser excited to
high-lying Rydberg s-states. We focus on a regime in which the laser driving is
strong compared to the interaction between Rydberg atoms. Here energetically
low-lying many-particle states can be calculated approximately from a quadratic
Hamiltonian. The potential usefulness of these states as a resource for the
creation of deterministic single-photon sources is illustrated. The properties
of these photon states are determined from the interplay between the particular
geometry of the lattice and the interatomic spacing.Comment: 12 pages, 8 figure
Spectral properties of finite laser-driven lattices of ultracold Rydberg atoms
We investigate the spectral properties of a finite laser-driven lattice of
ultracold Rydberg atoms exploiting the dipole blockade effect in the frozen
Rydberg gas regime. Uniform one-dimensional lattices as well as lattices with
variable spacings are considered. In the case of a weak laser coupling, we find
a multitude of many-body Rydberg states with well-defined excitation properties
which are adiabatically accessible starting from the ground state. A
comprehensive analysis of the degeneracies of the spectrum as well as of the
single and pair excitations numbers of the eigenstates is performed. In the
strong laser regime, analytical solutions for the pseudo-fermionic eigenmodes
are derived. Perturbative energy corrections for this approximative approach
are provided.Comment: 17 pages, 12 figure
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