Search results for "Modelli"

A systematic comparison of kinetic modelling methods generating parametric maps for [11C]-(R)-PK11195

2006

[(11)C]-(R)-PK11195 is presently the most widely used radiotracer for the monitoring of microglia activity in the central nervous system (CNS). Microglia, the resident immune cells of the brain, play a critical role in acute and chronic diseases of the central nervous system and in host defence against neoplasia. The purpose of this investigation was to evaluate the reliability and sensitivity of five kinetic modelling methods for the formation of parametric maps from dynamic [(11)C]-(R)-PK11195 studies. The methods we tested were the simplified reference tissue model (SRTM), basis pursuit, a simple target-to-reference ratio, the Logan plot and a wavelet based Logan plot. For the reliabilit…

Fluctuation-dissipation relations for Markov processes.

2005

The fluctuation-dissipation relation is calculated for stochastic models obeying a master equation with continuous time. In the general case of a nonstationary process, there appears to be no simple relation between the response and the correlation. Also, if one considers stationary processes, the linear response cannot be expressed via time-derivatives of the correlation function alone. In this case, an additional function, which has rarely been discussed previously, is required. This so-called asymmetry depends on the two times also relevant for the response and the correlation and it vanishes under equilibrium conditions. The asymmetry can be expressed in terms of the propagators and the…

Waiting for a new leader: Eras and transitions in Cosa Nostra

2019

Partendo dal controverso dibattito che negli ultimi anni ha visto in Italia – soprattutto i mezzi di comunicazione di massa e le agenzie investigative – disputare sullo “stato di salute” delle organizzazioni criminali mafiose, quasi a volerne stilare una discutibile classifica di offensività e di pericolosità, il capitolo si interroga sull’attuale e delicata fase attraversata da Cosa Nostra, facendo ricorso a una prospettiva analitica multiproblematica e multidisciplinare (rielaborando il cosiddetto paradigma della complessità proposto da Umberto Santino alla luce dei più recenti studi e delle nuove prospettive analitiche emerse) e dando conto delle numerose ricerche (oggi spesso orientate …

Cost analysis of a vaccination strategy for respiratory syncytial virus (RSV) in a network model

2010

[EN] In this paper an age-structured mathematical model for respiratory syncytial virus (RSV) is proposed where children younger than one year old, who are the most affected by this illness, are specially considered. Real data of hospitalized children in the Spanish region of Valencia are used in order to determine some seasonal parameters of the model. Once the parameters are determined, we propose a complete stochastic network model to study the seasonal evolution of the respiratory syncytial virus (RSV) epidemics. In this model every susceptible individual can acquire the disease after a random encounter with any infected individual in the social network. The edges of a complete graph co…

Domanda e offerta di consuòltazione psicologica nei contesti universitari

2005

Pattern formation and spatial correlation induced by the noise in two competing species

2004

We analyze the spatio-temporal patterns of two competing species in the presence of two white noise sources: an additive noise acting on the interaction parameter and a multiplicative noise which affects directly the dynamics of the species densities. We use a coupled map lattice (CML) with uniform initial conditions. We find a nonmonotonic behavior both of the pattern formation and the density correlation as a function of the multiplicative noise intensity.

Nonmonotonic behavior of spatiotemporal pattern formation in a noisy Lotka-Volterra system

2004

The noise-induced pattern formation in a population dynamical model of three interacting species in the coexistence regime is investigated. A coupled map lattice of Lotka-Volterra equations in the presence of multiplicative noise is used to analyze the spatiotemporal evolution. The spatial correlation of the species concentration as a function of time and of the noise intensity is investigated. A nonmonotonic behavior of the area of the patterns as a function of both noise intensity and evolution time is found.

Simulations of networked critical infrastructures

2018

Master's thesis Information- and communication technology IKT590 - University of Agder 2018 Critical infrastructure (CI) refers to assets that are essential for the functioning of a society and economy, such as telecommunication/ICT; energy generation, transmission and distribution; financial sector; etc. CIs are tightly coupled, creating a complex system where failures propagate from a disrupted CI to other CIs, aggravating and prolonging the societal impact through cascading effects. This thesis extends a system dynamic model by Eliza Canzani describing how a failed critical infrastructure that cannot deliver products and services impacts other critical infrastructures, and how a critical…

Innovative techniques for survey and communication of cultural heritage

2008

This paper deals with the survey and communications of Cultural Heritage through the development of innovative methodologies. The case of study is the polychrome wooden ceiling in the “Magna” Hall of “Palazzo Steri”. The “Steri”, built in the XIVth century by the noble family Chiaromonte, is at the present the headquarter of the Rector’s Office of Palermo University. A 3D model of the wooden ceiling has initially been carried out with laser-scanning and digital photogrammetric techniques; successively a multimodal interactive guide has been realized. The guide is integrated to the 3D model, so that visitors can navigate the virtual representation of the ancient wood ceiling and achieve, int…

3D survey and modelling of the main portico of the Cathedral of Monreale

2018

3D survey and modelling of Cultural Heritage allow to store a great deal of 3D data that can be managed for different purposes. 3D models can be used for documentation, restoration and knowledge of historic architectures and monuments. In this work, a 3D survey of the main portico of the Cathedral of Monreale (Palermo, Italy) was carried out. The paper presents the data acquisition process and the 3D modelling phase. The work is aimed to reconstruct a 3D model that could be used also to set up an HBIM (Heritage or Historic Building Information Modelling) of the main portico. The result of this study could be considered as a first test to implement an HBIM platform for the whole monumental c…