Generation of Noise Time Series with arbitrary Power Spectrum

Noise simulation is a very powerful tool in signal analysis helping to foresee the system performance in real experimental situations. Time series generation is however a hard challenge when a robust model of the noise sources is missing. We present here a simple computational technique which allows the generation of noise samples of fixed length, given a desired power spectrum. A few applications of the method are also discussed.Comment: 4 pages, 7 figure

Intracluster stars tracing motions in nearby clusters

Cosmological simulations of structure formation predict that galaxies are dramatically modified by galaxy harassment during the assembly of galaxy clusters, losing a substantial fraction of their stellar mass which today must be in the form of intracluster stars. Simulations predict non-uniform spatial and radial velocity distributions for these stars. Intracluster planetary nebulae are the only abundant component of the intracluster light whose kinematics can be measured at this time. Comparing these velocity distributions with simulations will provide a unique opportunity to investigate the hierarchical cluster formation process as it takes place in the nearby universe.Comment: 4 pages, 3 figures, to appear in the XXIst IAP Colloquium "Mass Profiles and Shapes of Cosmological Structures", Paris 4-9 July 2005, France, (Eds.) G. Mamon, F. Combes, C. Deffayet, B. Fort, EAS Publications Serie

The Planetary Nebulae Populations in the Local Group

Planetary nebulae have been used as tracers of light and kinematics for the stellar populations in early-type galaxies since more than twenty years. Several empirical properties have surfaced: for example the invariant bright cut-off of the planetary nebulae luminosity function and correlations of the luminosity specific PN number with the integrated properties of the parent stellar populations. These observed properties are poorly understood in terms of a simple model of a ionized nebula expanding around a non-evolving central star. In order to make further steps, we need to study self-contained systems at know distances whose PN populations are sufficiently nearby to permit investigation into their physical properties. The galaxies in the Local Group represent a valid proxies to study these late phases of evolved stellar populations with a spread of metallicities, $\alpha$-element enhancements, and star forming histories.Comment: 10 pages, 5 figures. To appear in "Lessons from the Local Group - A Conference in Honour of David Block and Bruce Elmegreen" (eds. Freeman, K.C., Elmegreen, B.G., Block, D.L. \& Woolway, M., SPRINGER: NEW YORK

Characterization of ZnSe scintillating bolometers for Double Beta Decay

ZnSe scintillating bolometers are good candidates for future Double Beta Decay searches, because of the 82Se high Q-value and thanks to the possibility of alpha background rejection on the basis of the scintillation signal. In this paper we report the characteristics and the anomalies observed in an extensive study of these devices. Among them, an unexpected high emission from alpha particles, accompanied with an unusual pattern of the light vs. heat scatter plot. The perspectives for the application of this kind of detectors to search for the Neutrinoless Double Beta Decay of 82Se are presented.Comment: 12 pages, 10 figure

CdWO4 scintillating bolometer for Double Beta Decay: Light and Heat anticorrelation, light yield and quenching factors

We report the performances of a 0.51 kg CdWO4 scintillating bolometer to be used for future Double Beta Decay Experiments. The simultaneous read-out of the heat and the scintillation light allows to discriminate between different interacting particles aiming at the disentanglement and the reduction of background contribution, key issue for next generation experiments. We will describe the observed anticorrelation between the heat and the light signal and we will show how this feature can be used in order to increase the energy resolution of the bolometer over the entire energy spectrum, improving up to a factor 2.6 on the 2615 keV line of 208Tl. The detector was tested in a 433 h background measurement that permitted to estimate extremely low internal trace contaminations of 232Th and 238U. The light yield of gamma/beta, alpha and neutrons is presented. Furthermore we developed a method in order to correctly evaluate the absolute thermal quenching factor of alpha particles in scintillating bolometers.Comment: 8 pages 7 figure

Internet Banking in Europe: a comparative analysis.

A key strategic issue for banks is the implementation of internet banking. The ‘click and mortar’ model that complements classical branch banking with online facilities is competing with pure internet banks. The objective of this paper is to compare the performance of these two models across countries, so as to examine the role of differences in the banking system and technological progress. A fuzzy cluster analysis on the performance of banks in Finland, Spain, Italy and the UK shows that internet banks are hard to distinguish from banks that follow a click and mortar strategy; country borders are more important. We therefore explain bank performance by a group of selected bank features, country-specific economic and IT indicators over the period 1995-2004. We find that the strategy of banking groups to incorporate internet banks reflects some competitive edge that these banks have in their business models. Extensive technological innovation boosts internet banking.Banks, Internet, Innovation.

Extragalactic planetary nebulae as mass tracers: biases in the estimate of dynamical quantities

Planetary Nebulae (PNe) are very important kinematical tracers of the outer regions of early-type galaxies, where the integrated light techniques fail. Under ad hoc assumptions, they allow measurements of rotation velocity and velocity dispersion profile from descrete radial velocity fields. We present the results on the precision allowed by different set of radial velocity samples, discuss the hypotheses in the analysis of descrete velocity fields and their impact on the inferred kinematics of the stellar population.Comment: 4 pages, 2 figures. To appear on ``Galaxy Dynamics: from Early Universe to the Present'', ASP Conf. Ser., F. Combes, G.A. Mamon and V. Charmandaris (eds.

Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centres. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies . We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 sqdeg region centred on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two PN populations are identified out to 150 kpc distance from the centre of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60-90 kpc from the centre of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.Comment: 8 pages, 3 figures, To appear in the proceedings of the IAU Symposium 317 "The General Assembly of Galaxy Halos: Structure, Origin and Evolution'', A. Bragaglia, M. Arnaboldi, M. Rejkuba & D. Romano, ed