Variational collocation for systems of coupled anharmonic oscillators

We have applied a collocation approach to obtain the numerical solution to the stationary Schr\"odinger equation for systems of coupled oscillators. The dependence of the discretized Hamiltonian on scale and angle parameters is exploited to obtain optimal convergence to the exact results. A careful comparison with results taken from the literature is performed, showing the advantages of the present approach.Comment: 14 pages, 10 table

Design and development of a low-cost, electricity-generating cooking Score-Stove™

SCORE (www.score.uk.com) a US$4M, 5 year international collaboration research project aims to improve the life quality of the 1.5 billion people worldwide who cook on an open fire and do not have access to electricity. SCORE market evaluations1 indicate that at the upper-cost target of$120 with 20 Watts of electricity 60 million people would afford the stove. At the lower-cost target of $40 and 100 Watts it would be affordable to over 1 billion people. In November 2010, a wood burning Score-Stove™ prototype successfully developed 23 watts of electricity based on a planar Thermo-Acoustic Engine (TAE) [2],[3],[4],[5],[6] design, indicating that the new Score-Stove™ is now ready to be engaged with manufacturers to gear up for volume production, and therefore to meet the social and cooking requirements of the rural poor people. The development to a large-volume, easy to manufacture, low-cost TAE cooking stove using elements of the formal design methodologies of BS 7000 and TRIZ are discussed. By breaking down the system requirements into cost targets for each module, performing rig testing, and design refinements it is believed that the upper-cost target is achievable with the right level of investment

Experimental ionization of atomic hydrogen with few-cycle pulses

We present the first experimental data on strong-field ionization of atomic hydrogen by few-cycle laser pulses. We obtain quantitative agreement at the 10% level between the data and an {\it ab initio} simulation over a wide range of laser intensities and electron energies

Is Quantum Chaos Weaker Than Classical Chaos?

We investigate chaotic behavior in a 2-D Hamiltonian system - oscillators with anharmonic coupling. We compare the classical system with quantum system. Via the quantum action, we construct Poincar\'{e} sections and compute Lyapunov exponents for the quantum system. We find that the quantum system is globally less chaotic than the classical system. We also observe with increasing energy the distribution of Lyapunov exponts approaching a Gaussian with a strong correlation between its mean value and energy.Comment: text (LaTeX) + 7 figs.(ps

Precise and accurate measurements of strong-field photoionisation and a transferrable laser intensity calibration standard

Ionization of atoms and molecules in strong laser fields is a fundamental process in many fields of research, especially in the emerging field of attosecond science. So far, demonstrably accurate data have only been acquired for atomic hydrogen (H), a species that is accessible to few investigators. Here we present measurements of the ionization yield for argon, krypton, and xenon with percentlevel accuracy, calibrated using H, in a laser regime widely used in attosecond science. We derive a transferrable calibration standard for laser peak intensity, accurate to 1.3%, that is based on a simple reference curve. In addition, our measurements provide a much-needed benchmark for testing models of ionisation in noble-gas atoms, such as the widely employed single-active electron approximation.Comment: Article: 5 pages, 2 figures, submitted to PRL (manuscript number LZ14457). Supplementary information: 7 pages, 6 figures, appended to end of main Articl

Adaptation of Australian houses and households to future heat waves

Climate change predictions indicate more extremes in weather conditions in the coming decades with more frequent and severe heat waves in certain locations including Australia. It is likely that the more vulnerable members of the community will be at risk during heat waves in the future from both health and financial perspectives. The trend towards fully air conditioned larger homes has already seen very large peaks in electricity demand during past heat waves with associated system failures. The impact of increased periods of hot weather, electricity price rises and system failure can be addressed in part through household behaviour; however it is concurrently exacerbated by housing designs which limit occupant choice. This paper employs outputs from the thermal analysis of typical Australian housing types to discuss this relationship between behaviour and design in future heat wave scenarios. Particular attention is given to populated regions forecast to experience a significant increase in heat waves in the future. Alterations to existing buildings and modifications of typical new house designs are utilised to demonstrate methods of reducing risks associated with extended periods of hot weather. In conclusion, a summary of the positive environmental and comfort implications of the modified designs is presented.Jasmine Palmer, Helen Bennetts, Stephen Pullen, Jian Zuo, Tony Ma, Nicholas Chilesh

Gibbs attractor: a chaotic nearly Hamiltonian system, driven by external harmonic force

A chaotic autonomous Hamiltonian systems, perturbed by small damping and small external force, harmonically dependent on time, can acquire a strange attractor with properties similar to that of the canonical distribution - the Gibbs attractor. The evolution of the energy in such systems can be described as the energy diffusion. For the nonlinear Pullen - Edmonds oscillator with two degrees of freedom the properties of the Gibbs attractor and their dependence on parameters of the perturbation are studied both analytically and numerically.Comment: 8 pages RevTeX, 3 figure

The Partition Function and Level Density for Yang-Mills-Higgs Quantum Mechanics

We calculate the partition function $Z(t)$ and the asymptotic integrated level density $N(E)$ for Yang-Mills-Higgs Quantum Mechanics for two and three dimensions ($n = 2, 3$). Due to the infinite volume of the phase space $\Gamma$ on energy shell for $n= 2$, it is not possible to disentangle completely the coupled oscillators ($x^2 y^2$-model) from the Higgs sector. The situation is different for $n = 3$ for which $\Gamma$ is finite. The transition from order to chaos in these systems is expressed by the corresponding transitions in $Z(t)$ and $N(E)$, analogous to the transitions in adjacent level spacing distribution from Poisson distribution to Wigner-Dyson distribution. We also discuss a related system with quartic coupled oscillators and two dimensional quartic free oscillators for which, contrary to YMHQM, both coupling constants are dimensionless.Comment: 10 pages, LaTeX; minor changes; version accepted for publication as a Letter in J. Phys.

Non-Abelian Excitations of the Quark-Gluon Plasma

We present new, non-abelian, solutions to the equations of motion which describe the collective excitations of a quark-gluon plasma at high temperature. These solutions correspond to spatially uniform color oscillations.Comment: 8 pages LaTex, 1 figure (not included; available upon request), Saclay preprint T94/0

Incorporating prior knowledge improves detection of differences in bacterial growth rate

BACKGROUND: Robust statistical detection of differences in the bacterial growth rate can be challenging, particularly when dealing with small differences or noisy data. The Bayesian approach provides a consistent framework for inferring model parameters and comparing hypotheses. The method captures the full uncertainty of parameter values, whilst making effective use of prior knowledge about a given system to improve estimation. RESULTS: We demonstrated the application of Bayesian analysis to bacterial growth curve comparison. Following extensive testing of the method, the analysis was applied to the large dataset of bacterial responses which are freely available at the web-resource, ComBase. Detection was found to be improved by using prior knowledge from clusters of previously analysed experimental results at similar environmental conditions. A comparison was also made to a more traditional statistical testing method, the F-test, and Bayesian analysis was found to perform more conclusively and to be capable of attributing significance to more subtle differences in growth rate. CONCLUSIONS: We have demonstrated that by making use of existing experimental knowledge, it is possible to significantly improve detection of differences in bacterial growth rate