Self-consistent Keldysh approach to quenches in weakly interacting Bose-Hubbard model

We present a non-equilibrium Green's functional approach to study the dynamics following a quench in weakly interacting Bose Hubbard model (BHM). The technique is based on the self-consistent solution of a set of equations which represents a particular case of the most general set of Hedin's equations for the interacting single-particle Green's function. We use the ladder approximation as a skeleton diagram for the two-particle scattering amplitude useful, through the self-energy in the Dyson equation, for finding the interacting single-particle Green's function. This scheme is then implemented numerically by a parallelized code. We exploit this approach to study the correlation propagation after a quench in the interaction parameter, for one (1D) and two (2D) dimensions. In particular, we show how our approach is able to recover the crossover from ballistic to diffusive regime by increasing the boson-boson interaction. Finally we also discuss the role of a thermal initial state on the dynamics both for 1D and 2D Bose Hubbard models, finding that surprisingly at high temperature a ballistic evolution is restored.Comment: 13 figure

Non-Blocking Signature of very large SOAP Messages

Data transfer and staging services are common components in Grid-based, or more generally, in service-oriented applications. Security mechanisms play a central role in such services, especially when they are deployed in sensitive application fields like e-health. The adoption of WS-Security and related standards to SOAP-based transfer services is, however, problematic as a straightforward adoption of SOAP with MTOM introduces considerable inefficiencies in the signature generation process when large data sets are involved. This paper proposes a non-blocking, signature generation approach enabling a stream-like processing with considerable performance enhancements.Comment: 13 pages, 5 figure

Non-Blocking Signature of very large SOAP Messages

Data transfer and staging services are common components in Grid-based, or more generally, in service-oriented applications. Security mechanisms play a central role in such services, especially when they are deployed in sensitive application fields like e-health. The adoption of WS-Security and related standards to SOAP-based transfer services is, however, problematic as a straightforward adoption of SOAP with MTOM introduces considerable inefficiencies in the signature generation process when large data sets are involved. This paper proposes a non-blocking, signature generation approach enabling a stream-like processing with considerable performance enhancements.Comment: 13 pages, 5 figure

Attenuation studies at 35 GHz

Instrumentation and preliminary results of studies of attenuation of 35 GHz radio signals transmitted through the atmosphere are reported. The purpose of this work is to provide information to supplement the ATS-5 downlink tests. Data on atmospheric losses at 35 GHz are being obtained by sun tracker techniques, sky temperature observations, and point-to-point transmissions

Two-measured variable method for wall interference assessment/correction

An iterative method for wall interference assessment and/or correction is presented for transonic flow conditions in wind tunnels equipped with two component velocity measurements on a single interface. The iterative method does not require modeling of the test article and tunnel wall boundary conditions. Analytical proof for the convergence and stability of the iterative method is shown in the subsonic flow regime. The numerical solutions are given for both 2-D and axisymmetrical cases at transonic speeds with the application of global Mach number correction

Australia's Carbon Tax: A Sheep in Wolf's Clothing?

The Australian Government has produced a CO2-equivalent tax proposal with a difference, it is a short prelude to an emission trading scheme that will allow the increasing rate of emissions to continue, while being a net cost to the Treasury. That cost extends to allowing major emitters to make guaranteed windfall profits from pollution permits. The emission trading scheme suffers numerous problems, but the issues raised show taxes can also be watered down and made ineffectual through concessions. Taxpayers will get no assets from the billions of dollars to be spent buying-off the coal generators or other polluters. The scheme hopes to stimulate private investors to create an additional 12 percent in renewable electricity generation by 2020. A serious emissions reducing alternative would be to create a nationalised electricity sector with 100 percent renewable energy within a decade. We explore the difficulties of implementing meaningful greenhouse gas taxes in Australia.greenhouse gases; taxation; emission trading; climate change; regulation; renewable energy; Australia

Articulation of Plural Values in Deliberative Monetary Valuation: Beyond Preference Economisation and Moralisation

The use of deliberative methods to assess environmental values in monetary terms has been motivated by the potential for small group discussion to help with preference formation and the inclusion of non-economic values. In this review, two broad approaches are identified: preference economisation and preference moralisation. The former is analytical, concentrates upon issues of poor respondent cognition and produces a narrow conception of value linked to utilitarianism. The latter emphasises political legitimacy, appeals to community values and tends to privilege arguments made in the public interest. Both approaches are shown to embrace forms of value convergence which undermine the prospects for value pluralism. As a result exclusion and predefinition of values dominates current practice. In order to maintain democratic credentials, the importance attributed to monetary value needs to be left as an open question to be addressed as part of a process determining an ‘agreement to pay’. To this end we identify a discourse-based approach as a third way consistent with the democratic and value plural potential of deliberative monetary valuation.environmental valuation; deliberation; stated preferences; democracy; willingness to pay; value pluralism