Let M be a von Neumann algebra, f a faithful normal state and denote by M^f the fixed point algebra of the modular group of f. Let U_M and U_{M^f} be the unitary groups of M and M^f. In this paper we study the quotient U_M/U_{M^f} endowed with two natural topologies: the one induced by the usual norm of M (called here usual topology), and the one

The High-Velocity Clouds (HVCs) observed in the Galactic neighbourhood, have been proposed to be remnants of the formation of the galaxies in the Local Group, having distances, and thus masses, predominantly of dark matter, considerably larger than hitherto hypothesized. This hypothesis is plausibly supported by observational evidence that their

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Based on a new large, homogeneous photometric database of 34 Galactic globular clusters (GGCs plus Palomar 12), a set of distance- and reddening- independent relative age indicators has been measured. The observed δ(V-I)2.5 and ΔVHBTO versus metallicity relations have been compared with the relations predicted by two recently updated libraries of

We report the discovery of two L dwarfs (the new spectral class defined for dwarfs cooler than the M type) in a two-epoch CCD proper motion survey of 413 square degrees, complemented by infrared photometry from DENIS. One of them has a strong lithium line, which for very cool dwarfs is a proof of brown dwarf status. The other is a common proper

The neutrino production rate strongly depends on the temperature, and a small variation of chemical composition in the central regions can imply a large variation of neutrino flux. For some values of their frequencies and wavenumbers, the internal waves e xcited at the bottom of the solar convective zone are able to propagate until the central