Projective moduli space of semistable principal sheaves for a reductive group

Let X be a smooth projective complex variety, and let G be an algebraic reductive complex group. We define the notion of principal G-sheaf, that generalises the notion of principal G-bundle. Then we define a notion of semistability, and construct the projective moduli space of semistable principal G-sheaves on X. This is a natural compactification of the moduli space of principal G-bundles. This is the announcement note presented by the second author in the conference held at Catania (11-13 April 2001), dedicated to the 60th birthday of Silvio Greco. Detailed proofs will appear elsewhere.Comment: 10 pages, LaTeX2e. Submitted to the conference proceedings of "Commutative Algebra and Algebraic Geometry", Catania, April 200

Fluids confined in wedges and by edges: From cluster integrals to thermodynamic properties referred to different regions

Recently, new insights in the relation between the geometry of the vessel that confines a fluid and its thermodynamic properties were traced through the study of cluster integrals for inhomogeneous fluids. In this work I analyze the thermodynamic properties of fluids confined in wedges or by edges, emphasizing on the question of the region to which these properties refer. In this context, the relations between the line-thermodynamic properties referred to different regions are derived as analytic functions of the dihedral angle $\alpha$ , for $0<\alpha<2\pi$ , which enables a unified approach to both edges and wedges. As a simple application of these results, I analyze the properties of the confined gas in the low-density regime. Finally, using recent analytic results for the second cluster integral of the confined hard sphere fluid, the low density behavior of the line thermodynamic properties is analytically studied up to order two in the density for $0<\alpha<2\pi$ and by adopting different reference regions.Comment: 8 pages, 7 figure

Circular dichroism simulated spectra of chiral gold nanoclusters: A dipole approximation

Circular dichroism (CD) spectra of chiral bare and thiol-passivated gold nanoclusters have been calculated within the dipole approximation. The calculated CD spectra show features that allow us to distinguish between clusters with different indexes of chirality. The main factor responsible of the differences in the CD lineshapes is the distribution of interatomic distances that characterize the chiral cluster geometry. These results provide theoretical support for the quantification of chirality and its measurement, using the CD lineshapes of chiral metal nanoclusters.Comment: 3 pages + 4 figure

Mechanisms for AAA and QoS Interaction

Proceedings of Third IEEE Workshop on Applications and Services in Wireless Networks, ASWN 2003. Bern, Switzerland, July 2-4, 2003.The interaction between Authentication, Authorization and Accounting (AAA) systems and the Quality of Service (QoS) infrastructure is to become a must in the near future. This interaction will allow rich control and management of both users and networks. DIAMETER and DiffServ are likely to turn into the future standards in AAA and QoS systems, but they are not designed to interact with each other. To face this, we propose a new Diameter-Diffserv interaction model and describe the Application Specific Module (ASM) implemented to allow this interaction. The ASM has been implemented and tested in a complete AAA-QoS IPv6 scenario

Surface term for the capillary condensation transitions in a slit geometry

It is shown that a bare simple fluid model (SFM) proposed some years ago for studying adsorption between two semi-infinite solid walls can be improved by modifying the surface term in the grand potential for the film phase. Such a correction substantially improves the agreement between the predictions for phase transitions provided by that SFM and results obtained from calculations carried out for $^4$He with the density-functional method at zero temperature. The corrective term depends on the strength of the adsorption potential and observables of bulk helium.Comment: 4 pages, 1 table and 5 figure