Double strength, maximum gain: optimising student learning via collaborative partnerships @ QUT

Queensland University of Technology (QUT) demonstrates a commitment to lifelong learning and strives to foster graduates who can function as competent professionals. In response, the University identifies a number of generic capabilities which all students should gain during the course of their study, the development of which has been undertaken as a shared responsibility by teaching staff and centralised academic-related support staff. It is within this context that QUT's teaching and learning support services (TALSS) and the library assumes responsibility for facilitating the development of information literacy and technology literacy. TALSS and the library have collaboratively developed and implemented a range of teaching and learning strategies and initiatives. This paper highlights a number of these initiatives. These initiatives are also supported by a network of specialists such as liaison librarians, student computing advisors, a transition officer and an information literacy coordinator

Continuum variational and diffusion quantum Monte Carlo calculations

This topical review describes the methodology of continuum variational and diffusion quantum Monte Carlo calculations. These stochastic methods are based on many-body wave functions and are capable of achieving very high accuracy. The algorithms are intrinsically parallel and well-suited to petascale computers, and the computational cost scales as a polynomial of the number of particles. A guide to the systems and topics which have been investigated using these methods is given. The bulk of the article is devoted to an overview of the basic quantum Monte Carlo methods, the forms and optimisation of wave functions, performing calculations within periodic boundary conditions, using pseudopotentials, excited-state calculations, sources of calculational inaccuracy, and calculating energy differences and forces

The chiral critical point of Nf=3 QCD at finite density to the order (mu/T)^4

QCD with three degenerate quark flavours at zero baryon density exhibits a first order thermal phase transition for small quark masses, which changes to a smooth crossover for some critical quark mass m^c_0, i.e. the chiral critical point. It is generally believed that as an (even) function of quark chemical potential, m_c(mu), the critical point moves to larger quark masses, constituting the critical endpoint of a first order phase transition in theories with m\geq m^c_0. To test this, we consider a Taylor expansion of m_c(mu) around mu=0 and determine the first two coefficients from lattice simulations with staggered fermions on N_t=4 lattices. We employ two different techniques: a) calculating the coefficients directly from a mu=0 ensemble using a novel finite difference method, and b) fitting them to simulation data obtained for imaginary chemical potentials. The mu^2 and mu^4 coefficients are found to be negative by both methods, with consistent absolute values. Combining both methods gives evidence that also the mu^6 coefficient is negative. Hence, on coarse N_t=4 lattices a three-flavour theory with m > m^c_0 does not possess a chiral critical endpoint for quark chemical potentials mu\lsim T. Simulations on finer lattices are required for reliable continuum physics. Possible implications for the QCD phase diagram are discussed.Comment: 15 pages, 8 figures. Published version, with additional cautionary statements, corrected typos, and updated last figur

Testing an Optimised Expansion on Z_2 Lattice Models

We test an optimised hopping parameter expansion on various Z_2 lattice scalar field models: the Ising model, a spin-one model and lambda (phi)^4. We do this by studying the critical indices for a variety of optimisation criteria, in a range of dimensions and with various trial actions. We work up to seventh order, thus going well beyond previous studies. We demonstrate how to use numerical methods to generate the high order diagrams and their corresponding expressions. These are then used to calculate results numerically and, in the case of the Ising model, we obtain some analytic results. We highlight problems with several optimisation schemes and show for the best scheme that the critical exponents are consistent with mean field results to at least 8 significant figures. We conclude that in its present form, such optimised lattice expansions do not seem to be capturing the non-perturbative infra-red physics near the critical points of scalar models.Comment: 47 pages, some figures in colour but will display fine in B

Mixture of Kernels and Iterated Semidirect Product of Diffeomorphisms Groups

In the framework of large deformation diffeomorphic metric mapping (LDDMM), we develop a multi-scale theory for the diffeomorphism group based on previous works. The purpose of the paper is (1) to develop in details a variational approach for multi-scale analysis of diffeomorphisms, (2) to generalise to several scales the semidirect product representation and (3) to illustrate the resulting diffeomorphic decomposition on synthetic and real images. We also show that the approaches presented in other papers and the mixture of kernels are equivalent.Comment: 21 pages, revised version without section on evaluatio

Meson Masses in the Unquenched Quark Model

A novel approach to calculating coupled-channel effects for bottomonium in the 3P0 framework using realistic wavefunctions is introduced in which the physical state is expanded in a basis set of harmonic oscillators. Other techniques of solving the unquenched system are also presented including perturbative, simple harmonic oscillator and unique valence approximations. The resulting (spin-averaged) mass shifts are calculated for an nS → 1S +1S transition and compared across the separate methods. It is determined that the largest effect on the mass shift across the various approaches is the accu-rate treatment of the wavefunction, which causes significant deviations from the simple harmonic oscillator approximation near threshold. It is also found that the inclusion of mixing between valence states due to meson loops has no effect at ground state energies but induces small differences at higher lying states. While conclusions are drawn about the relative effect each of the methods presented have on determining the mass shift due to unquench-ing, further research is suggested for other transitions to be assured in such conclusions

GPU-accelerated simulation of colloidal suspensions with direct hydrodynamic interactions

Solvent-mediated hydrodynamic interactions between colloidal particles can significantly alter their dynamics. We discuss the implementation of Stokesian dynamics in leading approximation for streaming processors as provided by the compute unified device architecture (CUDA) of recent graphics processors (GPUs). Thereby, the simulation of explicit solvent particles is avoided and hydrodynamic interactions can easily be accounted for in already available, highly accelerated molecular dynamics simulations. Special emphasis is put on efficient memory access and numerical stability. The algorithm is applied to the periodic sedimentation of a cluster of four suspended particles. Finally, we investigate the runtime performance of generic memory access patterns of complexity $O(N^2)$ for various GPU algorithms relying on either hardware cache or shared memory.Comment: to appear in a special issue of Eur. Phys. J. Special Topics on "Computer Simulations on GPUs

Towards a Cognitive Compute Continuum: An Architecture for Ad-Hoc Self-Managed Swarms

In this paper we introduce our vision of a Cognitive Computing Continuum to address the changing IT service provisioning towards a distributed, opportunistic, self-managed collaboration between heterogeneous devices outside the traditional data center boundaries. The focal point of this continuum are cognitive devices, which have to make decisions autonomously using their on-board computation and storage capacity based on information sensed from their environment. Such devices are moving and cannot rely on fixed infrastructure elements, but instead realise on-the-fly networking and thus frequently join and leave temporal swarms. All this creates novel demands for the underlying architecture and resource management, which must bridge the gap from edge to cloud environments, while keeping the QoS parameters within required boundaries. The paper presents an initial architecture and a resource management framework for the implementation of this type of IT service provisioning.Comment: 8 pages, CCGrid 2021 Cloud2Things Worksho