Prototype Platforms for Distributed Agreements

We present a prototype application for coordinating distributed agreements in multi-parties negotiations, where participants can dynamically join ongoing negotiations and where participants know only those parties they have interacted with. Our prototype is tailored to Ad-Hoc network scenarios involving the assignment of tasks for a rescue team operating over disaster areas. Our application is based on asynchronous communication and it exploits the d2pc protocol for committing or aborting a negotiation. Parties have been developed both in Jocaml+Perl and Polyphonic C. The implementation of the commit protocol allows components of both types to participate within the same negotiation.     

Effect of polymerization conditions on the microstructure of a liquid crystalline copolyester

The melt polycondensation of mixtures of sebacic acid (S), 4,4′‐diacetoxybiphenyl (B), and 4‐acetoxybenzoic acid (H), carried out for the synthesis of semiflexible liquid–crystalline copolyesters referred to as SBH 1 : 1 : x, has been studied with the aim of clarifying the effect of the reaction conditions on the microstructure and the thermal properties of the products. It has been shown that the segregation of a liquid–crystalline phase within the polymerizing mixture, coupled with the thermodynamic tendency of the two phases to undergo compositional differentiation as polymerization proceeds, is responsible for the formation of blocky, rather than ideally random, copolyesters with poor processibility, when the mole ratio of H to the other two monomers is higher than x ≈ 1.90. The results of this study have shown that this unwanted effect can be considerably limited by carrying out the polycondensation at a relatively high temperature from the very beginning, rather than by the standard technique involving progressive heating of the reaction mixture, thus allowing the production of SBH copolyesters with a higher degree of aromaticity. The results are discussed in terms of the relative rates of the condensation reactions, which are responsible for chain growth, and of the concurrent acidolysis and esterolysis reactions leading to copolyester sequence reorganization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 141–150, 2000     

Reactive systems, (semi-)saturated semantics and coalgebras on presheaves

The semantics of process calculi has traditionally been specified by labelled transition systems (ltss), but, with the development of name calculi, it turned out that reaction rules (i.e., unlabelled transition rules) are often more natural. This leads to the question of how behavioral equivalences (bisimilarity, trace equivalence, etc.) defined for lts can be transferred to unlabelled transition systems. Recently, in order to answer this question, several proposals have been made with the aim of automatically deriving an lts from reaction rules in such a way that the resulting equivalences are congruences. Furthermore, these equivalences should agree with the standard semantics, whenever one exists.In this paper, we propose saturated semantics, based on a weaker notion of observation and orthogonal to all the previous proposals, and we demonstrate the appropriateness of our semantics by means of two examples: logic programming and open Petri nets. We also show that saturated semantics can be efficiently characterized through the so called semi-saturated games. Finally, we provide coalgebraic models relying on presheaves.     

Cosmological Simulations and Data Exploration: a Testcase on the Usage of Grid Infrastructure

While new infrastructures for large computational challenges begin to be widely accessible to researchers, computational codes need to be re-designed to exploit new facilities. The Grid and the cloud computing concepts are changing the computational resource distribution and availability, and much effort start to be made to develop new codes for a better exploitation of new resources. This paper presents an example of the use of Grid resources, based on gLite middleware, to run cosmological simulations, that, up to now, are normally executed on Supercomputers. We have also used the Grid to explore and visualize the dataset. We discuss non particular the performance of FLY a parallel code implementing the octal-tree algorithm introduced by J. Barnes and P. Hut to compute the gravitational field efficiently. It simulates the evolution of the collisionless component of the material content of our Universe. FLY was originally developed to run on mainframe systems using the one-side communication paradigm, but we are now presenting a modified version of the computational algorithm to exploit the Grid environment. We also integrated the data exploration and visualization process on the Grid, to obtain preliminary results using the distributed facilities.     

Natural radionuclides in the rocks of the Valle del Cervo Pluton in Piedmont

Monitoring of the gamma radiation in Valle del Cervo Pluton was performed by determining U and Th contents in the main rock types cropping out over the entire area and pertaining to the granitic complex, syenitic complex and monzonitic complex. In particular, syenitic rocks were largely used as building and ornamental materials (e.g. Sienite della Balma). All the samples are fresh and do not present joints or fractures filled with U minerals. In the crushed samples the activity of uranium varies from 346 to 764 Bq/kg. Concentration of thorium varies from 202 to 478 Bq/kg. For all the analysed rocks uranium activity is higher than thorium one. The lowest value of radioactive concentration is referred to rocks of the granitic complex. The most active rocks are syenites. The data confirm the high activities of Valle del Cervo rock types, strongly connected with high K content of the source magma (geochemical signature); on the contrary, the activity seems to be not related to the location of the samples.     

Second order nonlinear optical networks with excellent poling stability from a new trifunctional thiophene based chromophore

Two new trifunctional thiophene based dyes suited for crosslinking were synthesised from the same structural core, i.e. 4-[[5-[(4-nitrophenyl)azo]-2-thienyl]azo]benzenamine. Crystal structure and second order nonlinear optical properties were determined on a related difunctional dye that can be considered as a representative and simplified model of the trifunctional compounds, determining on it the μβ value of 4950 × 10^?48 esu (6111 × 10^?80 C² m⁴ V^?2).The presence of three acrylic or hydroxyl functional groups in the dyes allowed to incorporate the chromophoric fragment into two different kinds of crosslinked materials possessing “frozen” long-lasting dipole order. The traditional guest-host approach used for one of them was exceeded by covalently anchoring the chromophore to a functionalised polymer in a three-dimensional unique network. In this way a promising NLO active material was obtained. The value of the d₃₃ coefficient (determined by SHG measurement using the Maker fringe technique) was 11 pm/V for the poled/crosslinked film. Very good thermal and temporal stability of the chromophore poling-induced dipole alignment was attained.     

Transmission Electron Microscopy and UV–vis–IR Spectroscopy Analysis of the Diameter Sorting of Carbon Nanotubes by Gradient Density Ultracentrifugation

Diameter separation of single‐walled carbon nanotubes is achieved via the density gradient ultracentrifugation process. Statistical analysis of the separated samples is performed using high‐resolution transmission electron microscopy (HRTEM). The evolution of the diameter distribution with respect to the gradient density is extracted by analyzing hundreds of HRTEM images, and the results are found to be consistent with those estimated by UV–vis–IR spectroscopy. The efficiency of the separation process can be quantitatively characterized by the standard deviation of the diameter distribution, which is determined from the TEM analyses. This particular study indicated that for electric arc nanotubes dispersed in sodium cholate, diameter sorting is more efficient in the upper part of the gradient.