Valentina Lanza | Université du Havre (original) (raw)

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Papers by Valentina Lanza

The reconstitution of a proper and functional vascular network is a major issue in tissue enginee... more The reconstitution of a proper and functional vascular network is a major issue in tissue engineering and regeneration. The limited success of current technologies may be related to the difficulties to build a vascular tree with correct geometric ratios for nutrient delivery. The present paper develops a mathematical model suggesting how an anisotropic vascular network can be built in vitro by using exogenous chemoattractant and chemorepellent. The formation of the network is strongly related to the nonlinear characteristics of the model.

2009 IEEE International Symposium on Circuits and Systems, 2009

... Feedback Systems Valentina Lanza Department of Physics Politecnico di Torino Torino, Italy Em... more ... Feedback Systems Valentina Lanza Department of Physics Politecnico di Torino Torino, Italy Email: valentina.lanza@polito.it Fernando Corinto Department of Electronics Politecnico di Torino Torino, Italy Email: fernando.corinto@polito.it ...

Proceedings of 2010 IEEE International Symposium on Circuits and Systems, 2010

Abstract—In order to describe genetic regulatory networks several deterministic models based on s... more Abstract—In order to describe genetic regulatory networks several deterministic models based on systems of nonlinear ordinary differential equations (ODEs) have been proposed. The Elowitz repressilator, modeled as a system of three genes that repress each other in a ring, is one ...

2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011

Locally Connected Oscillatory Networks (LCONs) are a special class of Cellular Neural Networks (C... more Locally Connected Oscillatory Networks (LCONs) are a special class of Cellular Neural Networks (CNNs) where each cell (neuron) exhibits time periodic behavior. In this paper we investigate the dynamics of LCONs whose neurons exhibit the coexistence of a stable equilibrium point and as table limit cycle. We consider ac onstant external stimulus applied to each neuron, which influences the neuron's

Systems with the coexistence of different stable attractors are widely exploited in systems biolo... more Systems with the coexistence of different stable attractors are widely exploited in systems biology in order to suitably model the differentiating processes arising in living cells. In order to describe genetic regulatory networks several deterministic models based on systems of nonlinear ordinary differential equations have been proposed.

2014 IEEE International Symposium on Circuits and Systems (ISCAS), 2014

2008 IEEE International Symposium on Circuits and Systems, 2008

Page 1. Spiral Waves in Bio-inspired Oscillatory Media Fernando Corinto Department of Electronics... more Page 1. Spiral Waves in Bio-inspired Oscillatory Media Fernando Corinto Department of Electronics Politecnico di Torino Torino, Italy Email: fernando.corinto@polito.it Valentina Lanza Department of Mathematics Politecnico di Torino Torino, Italy Email: valentina.lanza@polito.it ...

2009 International Joint Conference on Neural Networks, 2009

I. INTRODUCTION Cyclic Negative Feedback systems (CNF systems) are one of the most applied paradi... more I. INTRODUCTION Cyclic Negative Feedback systems (CNF systems) are one of the most applied paradigms to model many phe-nomena arising in systems biology: from gene regulation systems [1], [2] to metabolic [3] and cellular signal pathways [4], [5]. CNF systems have the ...

2008 11th International Workshop on Cellular Neural Networks and Their Applications, 2008

... Networks Fernando Corinto Department of Electronics Politecnico di Torino Torino, ItalyValent... more ... Networks Fernando Corinto Department of Electronics Politecnico di Torino Torino, ItalyValentina Lanza Department of Mathematics Politecnico di Torino Torino, Italy Marco Gilli Department of Electronics Politecnico di Torino Torino, Italy ...

IEEE International Symposium on Circuits and Systems, 2007

The aim of this work is to study periodic oscillations and bifurcations in oscillatory networks w... more The aim of this work is to study periodic oscillations and bifurcations in oscillatory networks with arbitrary couplings. In order to characterize each oscillator by using amplitude and phase variables, a method based on a generalized version of the describing function technique is proposed. It allows us to derive a set of ordinary differential equations governing the amplitude and phase

International Journal of Circuit Theory and Applications, 2007

The goal of this manuscript is to propose a method for investigating the global dynamics of nonli... more The goal of this manuscript is to propose a method for investigating the global dynamics of nonlinear oscillatory networks, with arbitrary couplings. The procedure is mainly based on the assumption that the dynamics of each oscillator is accurately described by a couple of variables, that is, the oscillator periodic orbits are represented through time-varying amplitude and phase variables. The proposed method allows one to derive a set of coupled nonlinear ordinary differential equations governing the time-varying amplitude and phase variables. By exploiting these nonlinear ordinary differential equations, the prediction of the total number of periodic oscillations and their bifurcations is more accurate and simpler with respect to the one given by the latest available methodologies. Furthermore, it is proved that this technique also works for weakly connected oscillatory networks. Finally, the method is applied to a chain of third-order oscillators (Chua's circuits) and the results are compared with those obtained via a numerical technique, based on the harmonic balance approach.

IEEE Transactions on Circuits and Systems II: Express Briefs, 2000

Spectral techniques, like harmonic balance, are classical numerical tools for designing nonlinear... more Spectral techniques, like harmonic balance, are classical numerical tools for designing nonlinear oscillators and microwave circuits. Recently these techniques have been exploited for investigating complex dynamics in nonlinear systems. In this manuscript we firstly show that limit cycle Floquet's multipliers and the related bifurcation phenomena can be estimated through a spectral approach, entirely based on the describing function technique. Then we consider some significant case studies, and we show that our method yields more accurate results than the other describing function-based approaches proposed in the literature.

Journal of Mathematical Biology, 2011

In this work we consider the regulation system present on the SPI1 pathogenicity island of Salmon... more In this work we consider the regulation system present on the SPI1 pathogenicity island of Salmonella enterica serovar Typhimurium. It is well-known that HilA is the central regulator in the overall scheme of SPI1 regulation and directly binds to virulence operons and activates their expression. The regulation of the expression of HilA is via a complex feed-forward loop involving three transcriptional activators: HilC, HilD and RtsA, and the negative regulator HilE. Our aim is to model VL developed the model and made all theoretical and numerical computations. MBB analyzed experimental data. All authors designed the project and wrote the paper.

The reconstitution of a proper and functional vascular network is a major issue in tissue enginee... more The reconstitution of a proper and functional vascular network is a major issue in tissue engineering and regeneration. The limited success of current technologies may be related to the difficulties to build a vascular tree with correct geometric ratios for nutrient delivery. The present paper develops a mathematical model suggesting how an anisotropic vascular network can be built in vitro by using exogenous chemoattractant and chemorepellent. The formation of the network is strongly related to the nonlinear characteristics of the model.

2009 IEEE International Symposium on Circuits and Systems, 2009

... Feedback Systems Valentina Lanza Department of Physics Politecnico di Torino Torino, Italy Em... more ... Feedback Systems Valentina Lanza Department of Physics Politecnico di Torino Torino, Italy Email: valentina.lanza@polito.it Fernando Corinto Department of Electronics Politecnico di Torino Torino, Italy Email: fernando.corinto@polito.it ...

Proceedings of 2010 IEEE International Symposium on Circuits and Systems, 2010

Abstract—In order to describe genetic regulatory networks several deterministic models based on s... more Abstract—In order to describe genetic regulatory networks several deterministic models based on systems of nonlinear ordinary differential equations (ODEs) have been proposed. The Elowitz repressilator, modeled as a system of three genes that repress each other in a ring, is one ...

2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011

Locally Connected Oscillatory Networks (LCONs) are a special class of Cellular Neural Networks (C... more Locally Connected Oscillatory Networks (LCONs) are a special class of Cellular Neural Networks (CNNs) where each cell (neuron) exhibits time periodic behavior. In this paper we investigate the dynamics of LCONs whose neurons exhibit the coexistence of a stable equilibrium point and as table limit cycle. We consider ac onstant external stimulus applied to each neuron, which influences the neuron's

Systems with the coexistence of different stable attractors are widely exploited in systems biolo... more Systems with the coexistence of different stable attractors are widely exploited in systems biology in order to suitably model the differentiating processes arising in living cells. In order to describe genetic regulatory networks several deterministic models based on systems of nonlinear ordinary differential equations have been proposed.

2014 IEEE International Symposium on Circuits and Systems (ISCAS), 2014

2008 IEEE International Symposium on Circuits and Systems, 2008

Page 1. Spiral Waves in Bio-inspired Oscillatory Media Fernando Corinto Department of Electronics... more Page 1. Spiral Waves in Bio-inspired Oscillatory Media Fernando Corinto Department of Electronics Politecnico di Torino Torino, Italy Email: fernando.corinto@polito.it Valentina Lanza Department of Mathematics Politecnico di Torino Torino, Italy Email: valentina.lanza@polito.it ...

2009 International Joint Conference on Neural Networks, 2009

I. INTRODUCTION Cyclic Negative Feedback systems (CNF systems) are one of the most applied paradi... more I. INTRODUCTION Cyclic Negative Feedback systems (CNF systems) are one of the most applied paradigms to model many phe-nomena arising in systems biology: from gene regulation systems [1], [2] to metabolic [3] and cellular signal pathways [4], [5]. CNF systems have the ...

2008 11th International Workshop on Cellular Neural Networks and Their Applications, 2008

... Networks Fernando Corinto Department of Electronics Politecnico di Torino Torino, ItalyValent... more ... Networks Fernando Corinto Department of Electronics Politecnico di Torino Torino, ItalyValentina Lanza Department of Mathematics Politecnico di Torino Torino, Italy Marco Gilli Department of Electronics Politecnico di Torino Torino, Italy ...

IEEE International Symposium on Circuits and Systems, 2007

The aim of this work is to study periodic oscillations and bifurcations in oscillatory networks w... more The aim of this work is to study periodic oscillations and bifurcations in oscillatory networks with arbitrary couplings. In order to characterize each oscillator by using amplitude and phase variables, a method based on a generalized version of the describing function technique is proposed. It allows us to derive a set of ordinary differential equations governing the amplitude and phase

International Journal of Circuit Theory and Applications, 2007

The goal of this manuscript is to propose a method for investigating the global dynamics of nonli... more The goal of this manuscript is to propose a method for investigating the global dynamics of nonlinear oscillatory networks, with arbitrary couplings. The procedure is mainly based on the assumption that the dynamics of each oscillator is accurately described by a couple of variables, that is, the oscillator periodic orbits are represented through time-varying amplitude and phase variables. The proposed method allows one to derive a set of coupled nonlinear ordinary differential equations governing the time-varying amplitude and phase variables. By exploiting these nonlinear ordinary differential equations, the prediction of the total number of periodic oscillations and their bifurcations is more accurate and simpler with respect to the one given by the latest available methodologies. Furthermore, it is proved that this technique also works for weakly connected oscillatory networks. Finally, the method is applied to a chain of third-order oscillators (Chua's circuits) and the results are compared with those obtained via a numerical technique, based on the harmonic balance approach.

IEEE Transactions on Circuits and Systems II: Express Briefs, 2000

Spectral techniques, like harmonic balance, are classical numerical tools for designing nonlinear... more Spectral techniques, like harmonic balance, are classical numerical tools for designing nonlinear oscillators and microwave circuits. Recently these techniques have been exploited for investigating complex dynamics in nonlinear systems. In this manuscript we firstly show that limit cycle Floquet's multipliers and the related bifurcation phenomena can be estimated through a spectral approach, entirely based on the describing function technique. Then we consider some significant case studies, and we show that our method yields more accurate results than the other describing function-based approaches proposed in the literature.

Journal of Mathematical Biology, 2011

In this work we consider the regulation system present on the SPI1 pathogenicity island of Salmon... more In this work we consider the regulation system present on the SPI1 pathogenicity island of Salmonella enterica serovar Typhimurium. It is well-known that HilA is the central regulator in the overall scheme of SPI1 regulation and directly binds to virulence operons and activates their expression. The regulation of the expression of HilA is via a complex feed-forward loop involving three transcriptional activators: HilC, HilD and RtsA, and the negative regulator HilE. Our aim is to model VL developed the model and made all theoretical and numerical computations. MBB analyzed experimental data. All authors designed the project and wrote the paper.