I’m an associate professor in the Department of Computer Science, Applied Mathematics and Statistics at the University of Girona, where I’m a member of the research project entitled Mathematical Modeling in Biology and Complex Networks.I received my Ph.D. degree in mathematical sciences from the University of Barcelona in 2005. My research interests broadly focus on structured population dynamics, biological evolution, and epidemic spreading over complex networks. I’ve made several postdoctoral research stays, I’m co-author of many papers in international journals and I’ve attended to many conferences around the world. I’m involved in teaching activities including, mainly, algebra Phone: +34 630367529 Address: Campus Montilivi s/n E-17003 Girona, Spain
Design of Reliable Communication Networks, Mar 4, 2013
ABSTRACT Epidemics theory has been used in different contexts in order to describe the propagatio... more ABSTRACT Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur, such as in other multiple failure scenarios, identifying the level of vulnerability offered by a network is one of the main challenges. In this paper, we present epidemic survivability, a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Moreover, this metric is able to identify the set of nodes which are more vulnerable under an epidemic attack. In addition, two applications of epidemic survivability are provided. First, we introduce epidemic criticality, a novel robustness metric for epidemic failure scenarios. A case study shows the utility of this new metric comparing several network topologies and epidemic intensities. Then, two immunization strategies are proposed: high epidemic survivability (HES) and high epidemic survivability adaptive (HESA). The presented results show that network vulnerability can be significantly reduced by using our proposals, compared to other well-known existing methods.
Systems with many components (individuals or local populations as cities, or metropolitan areas, ... more Systems with many components (individuals or local populations as cities, or metropolitan areas, or regions, …) connected by non-trivial associations or relationships can be statistically described by means of the formalism of complex networks which is based on descriptors like degree distributions, degree-degree correlations, etc. In the last years, many researchers from different fields have been using different approaches to model processes taking place on complex networks.
Gruppo di lavoro EPICO: Marta Luisa Ciofi degli Atti, Caterina Rizzo, Antonino Bella, Marco Massa... more Gruppo di lavoro EPICO: Marta Luisa Ciofi degli Atti, Caterina Rizzo, Antonino Bella, Marco Massari, Mimmo Iannelli, Antonella Lunelli, Andrea Pugliese, Jordi Ripoll, Piero Manfredi, Gianpaolo Scalia Tomba, Stefano Merler, Giuseppe Jurman, Cesare Furlanello
International Symposium on Computers in Education, Oct 1, 2012
ABSTRACT In online engineering studies, the monitoring of the learning process as well as the ass... more ABSTRACT In online engineering studies, the monitoring of the learning process as well as the assessment system are key aspects of teaching strategy. This paper examines an interactive continuous assessment system. It is based on three Wiris Quizzes taken over the semester in a Mathematical Analysis class at the Open University of Catalonia. These tests, with parameterized statements, are completed in the Moodle environment with the symbolic calculator program Wiris (www.wiris.com). The results of the teaching experience in a virtual classroom with 65 students and the comparison with earlier semesters are clearly positive: (a) the number of students who follow continuous assessment remains stable; (b) The distribution of continuous assessment marks increases considerably; (c) the number of students who fail has been reduced significantly, and (d) the satisfaction level of students regarding the subject, its contents and resources has improved notably.
Mathematical Methods in The Applied Sciences, Nov 17, 2017
In this paper we study the asymptotic behaviour of the solutions in linear models of population d... more In this paper we study the asymptotic behaviour of the solutions in linear models of population dynamics by means of the basic reproduction number R0. Our aim is to give a practical approach to the computation of the basic reproduction number in continuous‐time population models structured by age and/or space. The procedure is different depending on whether the density of newborns per time unit and the density of population belong to the same functional space or not. Three infinite‐dimensional examples are illustrated: a transport model for a cell population, a model of spatial diffusion of individuals in a habitat, and a model of migration of individuals between age‐structured local populations. For each model, we have highlighted the possible advantages of computing R0 instead of the Malthusian parameter.
We study the impact of an age-dependent interaction in a structured predator-prey model. We prese... more We study the impact of an age-dependent interaction in a structured predator-prey model. We present two approaches, the PDE (partial differential equation) and the renewal equation, highlighting the advantages of each one. We develop efficient numerical methods to compute the (un)stability of steady-states and the time-evolution of the interacting populations, in the form of oscillating orbits in the plane of prey birth-rate and predator population size. The asymptotic behavior when species interaction does not depend on age is completely determined through the age-profile and a predator-prey limit system of ODEs (ordinary differential equations). The appearance of a Hopf bifurcation is shown for a biologically meaningful age-dependent interaction, where the system transitions from a stable coexistence equilibrium to a collection of periodic orbits around it, and eventually to a stable limit cycle (isolated periodic orbit). Several explicit analytical solutions are used to test the ...
We consider a between-host model for a single epidemic outbreak of an infectious disease. Accordi... more We consider a between-host model for a single epidemic outbreak of an infectious disease. According to the progression of the disease, hosts are classified in regard to the pathogen load. Specifically, we are assuming four phases: non-infectious asymptomatic phase, infectious asymptomatic phase (key-feature of the model where individuals show up mild or no symptoms), infectious symptomatic phase and finally an immune phase. The system takes the form of a non-linear Markov chain in discrete time where linear transitions are based on geometric (main model) or negative-binomial (enhanced model) probability distributions. The whole system is reduced to a single non-linear renewal equation. Moreover, after linearization, at least two meaningful definitions of the basic reproduction number arise: firstly as the expected secondary asymptomatic cases produced by an asymptomatic primary case, and secondly as the expected number of symptomatic individuals that a symptomatic individual will pr...
In this work we study the asymptotic behaviour in linear models of population dynamics by means o... more In this work we study the asymptotic behaviour in linear models of population dynamics by means of the basic reproduction number R_0. Our aim is to give a practical approach to the computation of the reproduction number in continuous-time population models structured by age and/or space. The traditional approach to the study of linear continuous-time population dynamics is the computation of the Malthusian parameter , i.e. the exponential growth rate of the population. Yet, another equivalent approach is possible which takes the generational viewpoint, [2], [3], [5]. For each system, firstly one has to distinguish between birth terms and the other ones like mortality and transition terms. Then, the basic reproduction number is computed as the spectral radius of the next-generation operator. However, different interpretations of what is a birth event give rise to different expressions and results, [2] and [1]. For infinite-dimensional systems (e.g. PDE), the second approach is alway...
Design of Reliable Communication Networks, Mar 4, 2013
ABSTRACT Epidemics theory has been used in different contexts in order to describe the propagatio... more ABSTRACT Epidemics theory has been used in different contexts in order to describe the propagation of diseases, human interactions or natural phenomena. In computer science, virus spreading has been also characterized using epidemic models. Although in the past the use of epidemic models in telecommunication networks has not been extensively considered, nowadays, with the increasing computation capacity and complexity of operating systems of modern network devices (routers, switches, etc.), the study of possible epidemic-like failure scenarios must be taken into account. When epidemics occur, such as in other multiple failure scenarios, identifying the level of vulnerability offered by a network is one of the main challenges. In this paper, we present epidemic survivability, a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Moreover, this metric is able to identify the set of nodes which are more vulnerable under an epidemic attack. In addition, two applications of epidemic survivability are provided. First, we introduce epidemic criticality, a novel robustness metric for epidemic failure scenarios. A case study shows the utility of this new metric comparing several network topologies and epidemic intensities. Then, two immunization strategies are proposed: high epidemic survivability (HES) and high epidemic survivability adaptive (HESA). The presented results show that network vulnerability can be significantly reduced by using our proposals, compared to other well-known existing methods.
Systems with many components (individuals or local populations as cities, or metropolitan areas, ... more Systems with many components (individuals or local populations as cities, or metropolitan areas, or regions, …) connected by non-trivial associations or relationships can be statistically described by means of the formalism of complex networks which is based on descriptors like degree distributions, degree-degree correlations, etc. In the last years, many researchers from different fields have been using different approaches to model processes taking place on complex networks.
Gruppo di lavoro EPICO: Marta Luisa Ciofi degli Atti, Caterina Rizzo, Antonino Bella, Marco Massa... more Gruppo di lavoro EPICO: Marta Luisa Ciofi degli Atti, Caterina Rizzo, Antonino Bella, Marco Massari, Mimmo Iannelli, Antonella Lunelli, Andrea Pugliese, Jordi Ripoll, Piero Manfredi, Gianpaolo Scalia Tomba, Stefano Merler, Giuseppe Jurman, Cesare Furlanello
International Symposium on Computers in Education, Oct 1, 2012
ABSTRACT In online engineering studies, the monitoring of the learning process as well as the ass... more ABSTRACT In online engineering studies, the monitoring of the learning process as well as the assessment system are key aspects of teaching strategy. This paper examines an interactive continuous assessment system. It is based on three Wiris Quizzes taken over the semester in a Mathematical Analysis class at the Open University of Catalonia. These tests, with parameterized statements, are completed in the Moodle environment with the symbolic calculator program Wiris (www.wiris.com). The results of the teaching experience in a virtual classroom with 65 students and the comparison with earlier semesters are clearly positive: (a) the number of students who follow continuous assessment remains stable; (b) The distribution of continuous assessment marks increases considerably; (c) the number of students who fail has been reduced significantly, and (d) the satisfaction level of students regarding the subject, its contents and resources has improved notably.
Mathematical Methods in The Applied Sciences, Nov 17, 2017
In this paper we study the asymptotic behaviour of the solutions in linear models of population d... more In this paper we study the asymptotic behaviour of the solutions in linear models of population dynamics by means of the basic reproduction number R0. Our aim is to give a practical approach to the computation of the basic reproduction number in continuous‐time population models structured by age and/or space. The procedure is different depending on whether the density of newborns per time unit and the density of population belong to the same functional space or not. Three infinite‐dimensional examples are illustrated: a transport model for a cell population, a model of spatial diffusion of individuals in a habitat, and a model of migration of individuals between age‐structured local populations. For each model, we have highlighted the possible advantages of computing R0 instead of the Malthusian parameter.
We study the impact of an age-dependent interaction in a structured predator-prey model. We prese... more We study the impact of an age-dependent interaction in a structured predator-prey model. We present two approaches, the PDE (partial differential equation) and the renewal equation, highlighting the advantages of each one. We develop efficient numerical methods to compute the (un)stability of steady-states and the time-evolution of the interacting populations, in the form of oscillating orbits in the plane of prey birth-rate and predator population size. The asymptotic behavior when species interaction does not depend on age is completely determined through the age-profile and a predator-prey limit system of ODEs (ordinary differential equations). The appearance of a Hopf bifurcation is shown for a biologically meaningful age-dependent interaction, where the system transitions from a stable coexistence equilibrium to a collection of periodic orbits around it, and eventually to a stable limit cycle (isolated periodic orbit). Several explicit analytical solutions are used to test the ...
We consider a between-host model for a single epidemic outbreak of an infectious disease. Accordi... more We consider a between-host model for a single epidemic outbreak of an infectious disease. According to the progression of the disease, hosts are classified in regard to the pathogen load. Specifically, we are assuming four phases: non-infectious asymptomatic phase, infectious asymptomatic phase (key-feature of the model where individuals show up mild or no symptoms), infectious symptomatic phase and finally an immune phase. The system takes the form of a non-linear Markov chain in discrete time where linear transitions are based on geometric (main model) or negative-binomial (enhanced model) probability distributions. The whole system is reduced to a single non-linear renewal equation. Moreover, after linearization, at least two meaningful definitions of the basic reproduction number arise: firstly as the expected secondary asymptomatic cases produced by an asymptomatic primary case, and secondly as the expected number of symptomatic individuals that a symptomatic individual will pr...
In this work we study the asymptotic behaviour in linear models of population dynamics by means o... more In this work we study the asymptotic behaviour in linear models of population dynamics by means of the basic reproduction number R_0. Our aim is to give a practical approach to the computation of the reproduction number in continuous-time population models structured by age and/or space. The traditional approach to the study of linear continuous-time population dynamics is the computation of the Malthusian parameter , i.e. the exponential growth rate of the population. Yet, another equivalent approach is possible which takes the generational viewpoint, [2], [3], [5]. For each system, firstly one has to distinguish between birth terms and the other ones like mortality and transition terms. Then, the basic reproduction number is computed as the spectral radius of the next-generation operator. However, different interpretations of what is a birth event give rise to different expressions and results, [2] and [1]. For infinite-dimensional systems (e.g. PDE), the second approach is alway...
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