Effects of FSI, CR and BEC at Small Relative Momenta of Particles and W-mass Systematics at LEP

The effects of Final State Interactions(FSI), Colour Reconnection(CR) and Bose--Einstein Correlations(BEC) at small relative momenta of particles are discussed. The short review of the LEP results on BEC at Z-peak, on BEC between particles from different Ws in $e^+e^-\to W^+W^-$ events, and the W-mass systematics due to BEC is givenComment: 4 pages, LaTeX, with 1 fig. Presented at 32st International Symposium on Multiparticle Dynamics (ISMD 2002), Alushta, Ukraine, 7-13 Sep 200

Habitat suitability models and carrying capacity estimations for rock ptarmigans in a protected area of the Italian Alps

Rock ptarmigan populations in the Alps are suffering an overall decline, and management actions are needed to ensure their conservation. Yet wildlife management and conservation actions are often the consequences of political decisions taken by subjects that lack the scientific knowledge about the relationships between the environment and species ecology. Habitat suitability models are tools that translate these complex relationships into mathematical models and spatially explicit maps of potential presence and abundance of species that are easier to understand by people not experienced with the study of biological processes. In this study, I modelled the species-habitat relationships at two levels, by estimating the potential distribution and potential density of the species in a protected area of the Western Italian Alps. In particular, I took the results of a previous study carried out in the same area to estimate the probability of male occurrence by comparing the habitat structure in presence plots and random plots, respectively, by logistic regression analyses. Then, I applied the logistic regression equation to the same variables measured in hexagonal cells of a grid superimposed over the entire study area, and I obtained the map of the potential distribution of the species. Finally, I developed multiple regression analyses of male density estimated by distance sampling vs habitat variables, and I applied the results to the areas of potential distribution to forecast the potential density and therefore the carrying capacity of the study area. I obtained a potential distribution of 38.2 km2, with a potential average density of 5.1 males/km2. The latter was positively affected by the percentage cover of grassland and rocky grassland in the plots. The integrated approach that I used by combining models of occurrence and density allowed me to confirm and improve the results of previous works on rock ptarmigan predicted occurrence, to identify areas of conservation importance within the protected area and to give useful tools for spatially explicit management to the Natural Park administrators

Competition and access price regulation in the broadband market

We construct a model for differentiated Cournot competition between service-based and infrastructure-based firms, out of which one infrastructure-based firm (the incumbent) supplies to the service-based firms. We seek for and compare the socially optimal and the incumbent’s profit maximizing access price in two scenarios: (i) service-based firms and incumbent supply homogeneous services (partial differentiation), and (ii) all services are horizontally differentiated (uniform differentiation). We show that in both cases the incumbent never forecloses service-based firms if infrastructure-based competition is present or if services are somewhat differentiated. Under uniform differentiation the welfare optimizing access price is below marginal cost, hence the incumbent subsidizes the production of service-based firms and makes zero profit. In the case of partial differentiation, the same result obtains when both markets are concentrated. However, if markets are not concentrated, the socially optimal access fee exceeds the marginal cost.

Fluctuations in instantaneous frequency predict alpha amplitude during visual perception.

Rhythmic neural activity in the alpha band (8-13 Hz) is thought to have an important role in the selective processing of visual information. Typically, modulations in alpha amplitude and instantaneous frequency are thought to reflect independent mechanisms impacting dissociable aspects of visual information processing. However, in complex systems with interacting oscillators such as the brain, amplitude and frequency are mathematically dependent. Here, we record electroencephalography in human subjects and show that both alpha amplitude and instantaneous frequency predict behavioral performance in the same visual discrimination task. Consistent with a model of coupled oscillators, we show that fluctuations in instantaneous frequency predict alpha amplitude on a single trial basis, empirically demonstrating that these metrics are not independent. This interdependence suggests that changes in amplitude and instantaneous frequency reflect a common change in the excitatory and inhibitory neural activity that regulates alpha oscillations and visual information processing

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