The matrix Kadomtsev--Petviashvili equation as a source of integrable nonlinear equations

A new integrable class of Davey--Stewartson type systems of nonlinear partial differential equations (NPDEs) in 2+1 dimensions is derived from the matrix Kadomtsev--Petviashvili equation by means of an asymptotically exact nonlinear reduction method based on Fourier expansion and spatio-temporal rescaling. The integrability by the inverse scattering method is explicitly demonstrated, by applying the reduction technique also to the Lax pair of the starting matrix equation and thereby obtaining the Lax pair for the new class of systems of equations. The characteristics of the reduction method suggest that the new systems are likely to be of applicative relevance. A reduction to a system of two interacting complex fields is briefly described.Comment: arxiv version is already officia

A numerical study of planar arrays of correlated spin islands

We present our analysis of a system of interacting islands of XY spins on a triangular lattice that has been introduced a few years ago by Eley et al. to account for the phenomenology in experiments on tunable arrays of proximity coupled long superconductor-normal metal-superconductor junctions. The main features of the model are the separation of a local and a global interaction energy scale and the mesoscopic character of the spin islands. Upon lowering the temperature the model undergoes two crossovers corresponding to an increasing phase coherence on a single island and to the onset of global coherence across the array; the latter is a thermodynamical phase transition in the Ising universality class. The dependence of the second transition on the island edge-to-edge spacing is related to the proximity-effect of the coupling constant.Comment: 6 pages, 5 figures, accepted for publication in EPJ

Quality control facilities for large optical reflectors at ENEA-Casaccia for physics application

The paper describes the quality control facilities for large optical reflectors available at ENEA-Casaccia. Commercial and custom spectrophotometers allow to measure the reflectance; specular and diffused for flat samples, and specular for the full-size reflector. In the case of spherical shape, the 2f and the pin-hole optical tests give a quick evaluation of the focusing effectiveness and the curvature uniformity, respectively. An optical profilometer allows to accurately measure the reflector profile and its deviations from the project specifications

Chemical Composition and Antioxidant Activity of Propolis Prepared in Different Forms and in Different Solvents Useful for Finished Products

Different products from a unique propolis extract obtained by using various solvents such as hydroalcoholic, glycolic (98% propylene glycol), and glyceric solutions, and oil, as well as in powder form, named ESIT12, were prepared. The molecular composition of the different preparations was evaluated and their antioxidant activity determined. All the preparations showed a quite similar polyphenol composition and comparable percentage even if ESIT12 was found to be richer in phenolic acids (caffeic, coumaric, ferulic, and isoferulic). Overall, flavones and flavonols ranged from ~20% up to ~36% in the glyceric extract, while flavanones and diidroflavonols were between ~28% and ~41%. Besides their quite similar composition, glycolic and hydroalcoholic extracts were found to be richer in the total polyphenols content. When the antioxidant properties were determined for the four preparations, the activity was similar among them, thus revealing that it is strictly related to the polyphenols content for propolis products whose composition is quite comparable. To date, very few data are available on propolis composition in glyceric and glycolic extracts and information has never been published on propolis in oil. This study could be of interest to the food and nutraceutical industries to choose suitable solvents and conditions to produce propolis preparations useful for active finished products

Functional rare males in diploid parthenogenetic Artemia

Functional males that are produced occasionally in some asexual taxa - called 'rare males' - raise considerable evolutionary interest, as they might be involved in the origin of new parthenogenetic lineages. Diploid parthenogenetic Artemia produce rare males, which may retain the ability to mate with females of related sexual lineages. Here, we (i) describe the frequency of male progeny in populations of diploid parthenogenetic Artemia, (ii) characterize rare males morphologically, (iii) assess their reproductive role, using cross-mating experiments with sexual females of related species from Central Asia and characterize the F1 hybrid offspring viability and (iv) confirm genetically both the identity and functionality of rare males using DNA barcoding and microsatellite loci. Our result suggests that these males may have an evolutionary role through genetic exchange with related sexual species and that diploid parthenogenetic Artemia is a good model system to investigate the evolutionary transitions between sexual species and parthenogenetic strains. © 2013 European Society For Evolutionary Biology

Exact Distributed Load Centrality Computation: Algorithms, Convergence, and Applications to Distance Vector Routing

Many optimization techniques for networking protocols take advantage of topological information to improve performance. Often, the topological information at the core of these techniques is a centrality metric such as the Betweenness Centrality (BC) index. BC is, in fact, a centrality metric with many well-known successful applications documented in the literature, from resource allocation to routing. To compute BC, however, each node must run a centralized algorithm and needs to have the global topological knowledge; such requirements limit the feasibility of optimization procedures based on BC. To overcome restrictions of this kind, we present a novel distributed algorithm that requires only local information to compute an alternative similar metric, called Load Centrality (LC). We present the new algorithm together with a proof of its convergence and the analysis of its time complexity. The proposed algorithm is general enough to be integrated with any distance vector (DV) routing protocol. In support of this claim, we provide an implementation on top of Babel, a real-world DV protocol. We use this implementation in an emulation framework to show how LC can be exploited to reduce Babel's convergence time upon node failure, without increasing control overhead. As a key step towards the adoption of centrality-based optimization for routing, we study how the algorithm can be incrementally introduced in a network running a DV routing protocol. We show that even when only a small fraction of nodes participate in the protocol, the algorithm accurately ranks nodes according to their centrality

PURIFICATION OF PROPOLIS FROM POLYCYCLIC AROMATIC HYDROCARBONS AND PRESERVATION OF ACTIVE POLYPHENOL COMPONENT.

Organic pollutants have become an increasing concern due to their potential of mutagenicity, carcinogenicity, teratogenicity and high bioaccumulation. The adverse effects on health and environment caused by specific organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) have been considered as critical problems. The European Food Safety Authority (EFSA) has defined 16 priority PAH that are both genotoxic and carcinogenic and identified eight (PAH8) or four (PAH4) priority PAH as good indicators of the toxicity and occurrence of PAH in food. Several available techniques (photocatalytic degradation, combined photo-fenton and ultrasound, advanced oxidation, aerobic degradation, filtration, ozonation, coagulation, flocculation, distillation, extraction, precipitation, and adsorption, etc.) have been developed for PAH removal. Food supplements containing propolis were also found to show relatively high PAHs. As a consequence, a main goal is to adopt purification procedures to remove PAH from propolis and preserve its polyphenol components before its use in finished products. Here we report an extractive procedure (M.E.D., Multi Dynamic Extraction) able to purify propolis from a great content of PAH by using a balanced mixture of organic and water solvents. Obtained propolis extracts are still rich in polyphenols and glycosylated derivatives showing PAH8 and specific benzo[a]pyrene content below limits recommended by EFSA