On the Expressive Power of Klaim-based Calculi
We study the expressive power of variants of KLAIM, an experimental language with programming primitives for network-aware programming that combines the process algebra approach with the coordination-oriented one. KLAIM has proved to be suitable for programming a wide range of distributed applications with agents and code mobility, and has been implemented on the top of a runtime system written in Java. In this paper, the expressivity of its constructs is tested by distilling from it a few, more and more foundational, languages and by studying the encoding of each of them into a simpler one. The expressive power of the considered calculi is finally tested by comparing one of them with asynchronous π-calculus.
We consider the vacuum energy of the electromagnetic field in the background of spherically symmetric dielectrics, subject to a cut-off frequency in the dispersion relations. The effect of this frequency dependent boundary condition between media is described in terms of the {\it incomplete} $\zeta$-functions of the problem. The use of the Debye asymptotic expansion for Bessel functions allows to determine the dominant (volume, area, ...) terms in the Casimir energy. The application of these expressions to the case of a gas bubble immersed in water is discussed, and results consistent with Schwinger's proposal about the role the Casimir energy plays in sonoluminescence are found. ::: PACS: 03.70.+k,12.20.Ds,78.60.Mq