Simulations of Bose fields at finite temperature

We introduce a time-dependent projected Gross-Pitaevskii equation to describe a partially condensed homogeneous Bose gas, and find that this equation will evolve randomized initial wave functions to equilibrium. We compare our numerical data to the predictions of a gapless, second order theory of Bose-Einstein condensation [S. A. Morgan, J. Phys. B 33, 3847 (2000)], and find that we can determine a temperature when the theory is valid. As the Gross-Pitaevskii equation is nonperturbative, we expect that it can describe the correct thermal behavior of a Bose gas as long as all relevant modes are highly occupied. Our method could be applied to other boson fields.

Pair correlations in a finite-temperature 1D Bose gas

We calculate the two-particle local correlation for an interacting 1D Bose gas at finite temperature and classify various physical regimes. We present the exact numerical solution by using the Yang-Yang equations and Hellmann-Feynman theorem and develop analytical approaches. Our results draw prospects for identifying the regimes of coherent output of an atom laser, and of finite-temperature “fermionization” through the measurement of the rates of two-body inelastic processes, such as photoassociation.

Quantum symmetries and the Weyl–Wigner product of group representations

In the usual formulation of quantum mechanics, groups of automorphisms of quantum states have ray representations by unitary and antiunitary operators on complex Hilbert space, in accordance with Wigner's theorem. In the phase-space formulation, they have real, true unitary representations in the space of square-integrable functions on phase space. Each such phase-space representation is a Weyl–Wigner product of the corresponding Hilbert space representation with its contragredient, and these can be recovered by 'factorizing' the Weyl–Wigner product. However, not every real, unitary representation on phase space corresponds to a group of automorphisms, so not every such representation is in the form of a Weyl–Wigner product and can be factorized. The conditions under which this is possible are examined. Examples are presented.

A unified and complete construction of all finite dimensional irreducible representations of gl(2|2)

Representations of the non-semisimple superalgebra gl(2/2) in the standard basis are investigated by means of the vector coherent state method and boson-fermion realization. All finite-dimensional irreducible typical and atypical representations and lowest weight (indecomposable) Kac modules of gl(2/2) are constructed explicity through the explicit construction of all gl(2) circle plus gl(2) particle states (multiplets) in terms of boson and fermion creation operators in the super-Fock space. This gives a unified and complete treatment of finite-dimensional representations of gl(2/2) in explicit form, essential for the construction of primary fields of the corresponding current superalgebra at arbitrary level.

Undergraduate student experiences and perceptions of group projects

This paper reports the experiences and perceptions of student group projects of three cohorts of undergraduates: a 3rd year capstone course in professional communication (N = 54), a 3rd year elective in chemical engineering (N = 29), and a core 2nd-year course in chemical engineering (N = 74).

Megan Henderson and Gay Walkington in Wattle Dance Group, Christmas 1968

Megan Henderson and Gay Walkington in Wattle Dance Group, Christmas 1968. The Wattle Dance Group met every Saturday in the Trades Hall, Brisbane, Australia. They held an concert at the end of each year. Janet Henderson was the mainstay and taught along with a few others. Jean Leary was the pianist. She took over from Eva Bacon.

June Hill in Wattle Dance Group, Christmas 1968

June Hill in Wattle Dance Group, Christmas 1968. The Wattle Dance Group met every Saturday in the Trades Hall, Brisbane, Australia. They held an concert at the end of each year. Janet Henderson was the mainstay and taught along with a few others. Jean Leary was the pianist. She took over from Eva Bacon.

Julie Walkington and Karlin Bracegirdle in Wattle Dance Group, Christmas 1968

Julie Walkington and Karlin Bracegirdle in Wattle Dance Group, Christmas 1968. The Wattle Dance Group met every Saturday in the Trades Hall, Brisbane, Australia. They held an concert at the end of each year. Janet Henderson was the mainstay and taught along with a few others. Jean Leary was the pianist. She took over from Eva Bacon.

A finite integral transform technique for solving the diffusion-reaction equation with Michaelis-Menten kinetics

An approximate analytical technique employing a finite integral transform is developed to solve the reaction diffusion problem with Michaelis-Menten kinetics in a solid of general shape. A simple infinite series solution for the substrate concentration is obtained as a function of the Thiele modulus, modified Sherwood number, and Michaelis constant. An iteration scheme is developed to bring the approximate solution closer to the exact solution. Comparison with the known exact solutions for slab geometry (quadrature) and numerically exact solutions for spherical geometry (orthogonal collocation) shows excellent agreement for all values of the Thiele modulus and Michaelis constant.

The Indotriradites dolianitii Morphon, a distinctive group of miospore species from the Lower Carboniferous of Gondwana

An emended diagnosis and generic reallocation are proposed for the trilete miospore Indotriradites dolianitii (Daemon, 1974) Loboziak et al., comb. nov. A new species, I. daemonii Loboziak et al., sp. nov., from Viséan strata of Western Gondwana, is erected. These two species, together with I. zosteriformis (Playford et Satterthwait) Playford, 1991 from the Viséan of Australia, belong to a cohesive morphological miospore category, here termed the Indotriradites dolianitii Morphon, which is evidently restricted to the Lower Carboniferous of Gondwana.

Prevention of child behavior problems through universal implementation of a group behavioral family intervention.

The aim of this mental health promotion initiative was to evaluate the effectiveness of a universally delivered group behavioral family intervention (BFI) in preventing behavior problems in children. This study investigates the transferability of an efficacious clinical program to a universal prevention intervention delivered through child and community health services targeting parents of preschoolers within a metropolitan health region. A quasiexperimental two-group (BFI, n=804 vs. Comparison group, n=806) longitudinal design followed preschool aged children and their parents over a 2-year period. BFI was associated with significant reductions in parent-reported levels of dysfunctional parenting and parent-reported levels of child behavior problems. Effect sizes on child behavior problems ranged from large (.83) to moderate (.47). Positive and significant effects were also observed in parent mental health, marital adjustment, and levels of child rearing conflict. Findings are discussed with respect to their implication for significant population reductions in child behavior problems as well as the pragmatic challenges for prevention science in encouraging both the evaluation and uptake of preventive initiatives in real world settings.

A demonstration of artificial dissipation effects in some finite volume solution methods for the Navier-Stokes equations

The artificial dissipation effects in some solutions obtained with a Navier-Stokes flow solver are demonstrated. The solvers were used to calculate the flow of an artificially dissipative fluid, which is a fluid having dissipative properties which arise entirely from the solution method itself. This was done by setting the viscosity and heat conduction coefficients in the Navier-Stokes solvers to zero everywhere inside the flow, while at the same time applying the usual no-slip and thermal conducting boundary conditions at solid boundaries. An artificially dissipative flow solution is found where the dissipation depends entirely on the solver itself. If the difference between the solutions obtained with the viscosity and thermal conductivity set to zero and their correct values is small, it is clear that the artificial dissipation is dominating and the solutions are unreliable.

Australian Newspaper History Group Newsletter

Current findings, news and announcements related to the history of Australian newspapers.

Australian Newspaper History Group Newsletter

Current findings, news and announcements related to the history of Australian newspapers.