Tecnologie per l\u27esecuzione di codice distribuito attraverso World Wide Web

This work describes the technology for the execution of a distributed code through the World Wide Web.Il modello di sicurezza proposto da Java ?e sicuramente molto complesso e ricco di caratteristiche che, per essere comprese ed utilizzate in modo realmente sicuro, richiedono competenze ben specifiche. Al tempo stesso, l\u27architettura per codice mobile proposta dall\u27ambiente Java, ?e senza ombra di dubbio la pi?u completa e affidabile presente sul mercato. Questo non significa che Java garantisce la sicurezza assoluta, cosa che ?e praticamente impossibile da raggiungere ma che ?e in grado di limitare i rischi che si accettano quando si collega una macchina alla rete

False beliefs and naive beliefs: They can be good for you

Naive physics beliefs can be systematically mistaken. They provide a useful test-bed because they are common, and also because their existence must rely on some adaptive advantage, within a given context. In the second part of the commentary we ask questions about when a whole family of misbeliefs should be considered together as a single phenomenon

Bihamiltonian Reductions and W_n Algebras

We discuss the geometry of the Marsden-Ratiu reduction theorem for a bihamiltonian manifold. We consider the case of the manifolds associated with the Gel'fand-Dickey theory, i.e., loop algebras over sl(n+1). We provide an explicit identification, tailored on the MR reduction, of the Adler-Gel'fand-Dickey brackets with the Poisson brackets on the MR-reduced bihamiltonian manifold N. Such an identification relies on a suitable immersion of the space of sections of the cotangent bundle of N into the algebra of pseudo differential operators connected to geometrical features of the theory of (classical) W_n algebras.Comment: LaTeX2e, 23 pages, to be published in J. Geom. Phy

A Note on Fractional KdV Hierarchies

We introduce a hierarchy of mutually commuting dynamical systems on a finite number of Laurent series. This hierarchy can be seen as a prolongation of the KP hierarchy, or a ``reduction'' in which the space coordinate is identified with an arbitrarily chosen time of a bigger dynamical system. Fractional KdV hierarchies are gotten by means of further reductions, obtained by constraining the Laurent series. The case of sl(3)^2 and its bihamiltonian structure are discussed in detail.Comment: Final version to appear in J. Math. Phys. Some changes in the order of presentation, with more emphasis on the geometrical picture. One figure added (using epsf.sty). 30 pages, Late

Quantum Kicked Dynamics and Classical Diffusion

We consider the quantum counterpart of the kicked harmonic oscillator showing that it undergoes the effect of delocalization in momentum when the classical diffusional threshold is obeyed. For this case the ratio between the oscillator frequency and the frequency of the kick is a rational number, strictly in analogy with the classical case that does not obey the Kolmogorov-Arnold-Moser theorem as the unperturbed motion is degenerate. A tight-binding formulation is derived showing that there is not delocalization in momentum for irrational ratio of the above frequencies. In this way, it is straightforwardly seen that the behavior of the quantum kicked rotator is strictly similar to the one of the quantum kicked harmonic oscillator, although the former, in the classical limit, obeys the Kolmogorov-Arnold-Moser theorem.Comment: 9 pages, LaTeX. Comments are welcom

A 3-component extension of the Camassa-Holm hierarchy

We introduce a bi-Hamiltonian hierarchy on the loop-algebra of sl(2) endowed with a suitable Poisson pair. It gives rise to the usual CH hierarchy by means of a bi-Hamiltonian reduction, and its first nontrivial flow provides a 3-component extension of the CH equation.Comment: 15 pages; minor changes; to appear in Letters in Mathematical Physic

Diversity within Borrelia burgdorferi sensu lato genospecies in Switzerland by recA gene sequence

A total of 874 Ixodes ricinus ticks were collected in Switzerland to investigate the genetic diversity of the Borrelia population. We integrated to the RT-PCR method the DNA sequence analysis of a 162-bp fragment of the recA gene. Five genospecies were detected: Borrelia afzelii, Borrelia burgdorferi s.s., Borrelia garinii, Borrelia valaisiana, and Borrelia lusitaniae. A heterogeneous distribution was observed within the B. burgdorferi s.l. genospecies. The most prevalent and diverse genospecies found in Switzerland was Borrelia afzelii, which might suggest a rapid evolution of this genospecie

NEW REMAINS OF CASATIA THERMOPHILA (CETACEA, MONODONTIDAE) FROM THE LOWER PLIOCENE MARINE VERTEBRATE-BEARING LOCALITY OF ARCILLE (TUSCANY, ITALY)

An incomplete cranium, three cervicals (including the axis) and two likely lumbars of a monodontid cetacean are here described from lower Pliocene (ca. 5.1–4.5 Ma) marine sandstones cropping out at Arcille (Grosseto Province, Tuscany, Italy). This fossil find comes from the same locality as the holotype of Casatia thermophila, which it resembles in terms of overall size and cranial morphology, and especially, by displaying a similarly depressed portion of the dorsal surface of the premaxillae anterior to the premaxillary sac fossae and medial to the anteromedial sulci. Our new find is thus assigned to C. thermophila, and significant anatomical parts that are missing in the holotype are described in order to improve the diagnosis of this monodontid species. Some dentigerous fragments of the maxillae hint at a homodont and polydont dentition, which in turn suggests a ram prey capture method that differs from the highly derived suction method that is proper of extant monodontids. This second find of C. thermophila from the warm-water Arcille palaeoenvironment lends further support to the hypothesis that monodontids once thrived in tropical and subtropical habitats