Macroscopic Features of Light Heavy-Ion Fission Reactions

Global macroscopic features observed in the fully-damped binary processes in light di-nuclear systems, such as limiting angular momenta, mean total kinetic energies and energy thresholds for fusion-fission processes (''fission thresholds") are presented. Their deduced systematics are consistent with that obtained for heavier systems and follow a fusion-fission picture which can be described by a realistic rotating liquid drop model considering diffuse-surface and finite-nuclear-range effects.Comment: 8 pages(REVTeX), 3 figures available upon request, to appear in Phys. Rev.

On the coupling of vector fields to the Gauss-Bonnet invariant

Inflationary models including vector fields have attracted a great deal of attention over the past decade. Such an interest owes to the fact that they might contribute to, or even be fully responsible for, the curvature perturbation imprinted in the CMB. However, the necessary breaking of the vector field's conformal invariance during inflation is not without problems. In recent years it has been realized that a number of instabilities endangering the consistency of the theory arise when the conformal invariance is broken by means of a non-minimal coupling to gravity. In this paper we consider a massive vector field non-minimally coupled to gravity through the Gauss-Bonnet invariant, and investigate whether the vector can obtain a nearly scale-invariant perturbation spectrum while evading the emergence of perturbative instabilities. We find that the strength of the coupling must be extremely small if the vector field is to have a chance to contribute to the total curvature perturbation.Comment: 8 pages, 1 figur

Binary Decay of Light Nuclear Systems

A review of the characteristic features found in fully energy-damped, binarydecay yields from light heavy-ion reactions with $20\leq A_{target} + A_{projectile}\leq 80$ is presented. The different aspects of these yields that have been used to support models of compound-nucleus (CN) fission and deep-inelastic dinucleus orbiting are highlighted. Cross section calculations based on the statistical phase space at different stages of the reaction are presented and compared to the experimental results. Although the statistical models are found to reproduce most of the observed experimental behaviors, an additional reaction component corresponding to a heavy-ion resonance or orbiting mechanism is also evident in certain systems. The system dependence of this second component is discussed. The extent to which the binary yields in very light systems $(A_{CN} \leq 32)$ can be viewed as resulting from a fusion-fission mechanism is explored. A number of unresolved questions, such as whether the different observed behaviors reflect characteristically different reaction times, are discussed.Comment: 79 pages REVTeX file, 39 ps Figures included - to be publihed in Physics Report

Run-Time Selection of Coordination Mechanisms in Multi-Agent Systems

This paper presents a framework that enables autonomous agents to dynamically select the mechanism they employ in order to coordinate their inter-related activities. Adopting this framework means coordination mechanisms move from the realm of being imposed upon the system at design time, to something that the agents select at run-time in order to fit their prevailing circumstances and their current coordination needs. Empirical analysis is used to evaluate the effect of various design alternatives for the agent's decision making mechanisms and for the coordination mechanisms themselves