Frequency Dependent Viscosity Near the Critical Point: The Scale to Two Loop Order

The recent accurate measurements of Berg, Moldover and Zimmerli of the viscoelastic effect near the critical point of xenon has shown that the scale factor involved in the frequency scaling is about twice the scale factor obtained theoretically. We show that this discrepancy is a consequence of using first order perturbation theory. Including two loop contribution goes a long way towards removing the discrepancy.Comment: No of pages:7,Submitted to PR-E(Rapid Communication),No of EPS files:

Fast magnetic reconnection in laser-produced plasma bubbles

Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pile-up at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with two-fluid effects, we find that the ultimate reconnection time is insensitive to the nominal system Alfven time.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let

Activity diagrams: a formal framework to model business processes and code generation

Activity Diagram is an important component of the set of diagrams used in UML. The OMG document on UML 2.0 proposes a Petri net based semantics for Activity Diagrams. While Petri net based approach is useful and interesting, it does not exploit the underlying inherent reactive behaviour of activity diagrams. In the first part of the paper, we shall capture activity diagrams in synchronous language framework to arrive at executional models which will be useful in model based design of software. This also enables validated code generation using code generation mechanism of synchronous language environments such as Esterel and its programming environments. Further, the framework leads to scalable verification methods. The traditional semantics proposed in OMG standard need enrichment when the activities are prone to failure and need compensating actions. Such extensions are expected to have applications in modelling complex business processes. In the second part of the paper, we propose an enrichment of the UML Activity Diagrams that include compensable actions. We shall use some of the foundations on Compensable Transactions and Communicating Sequential Processes due to Tony Hoare. This enriched formalism allows UML Activity Diagrams to model business processes that can fail and require compensating actions