Asymptotic decay under nonlinear and noncoercive dissipative effects for electrical conduction in biological tissues

We consider a nonlinear model for electrical conduction in biological tissues. The nonlinearity appears in the interface condition prescribed on the cell membrane. The purpose of this paper is proving asymptotic convergence for large times to a periodic solution when time-periodic boundary data are assigned. The novelty here is that we allow the nonlinearity to be noncoercive. We consider both the homogenized and the non-homogenized version of the problem

Variable Support Control for the Wave Equation: A Multiplier Approach

We study the controllability of the multidimensional wave equation in a bounded domain with Dirichlet boundary condition, in which the support of the control is allowed to change over time. The exact controllability is reduced to the proof of the observability inequality, which is proven by a multiplier method. Besides our main results, we present some applications

Alternating and variable controls for the wave equation

The present article discusses the exact observability of the wave equation when the observation subset of the boundary is variable in time. In the one-dimensional case, we prove an equivalent condition for the exact observability, which takes into account only the location in time of the observation. To this end we use Fourier series. Then we investigate the two specific cases of single exchange of the control position, and of exchange at a constant rate. In the multi-dimensional case, we analyse sufficient conditions for the exact observability relying on the multiplier method. In the last section, the multi-dimensional results are applied to specific settings and some connections between the one and multi-dimensional case are discussed; furthermore some open problems are presented.Comment: The original publication is available at www.esaim-cocv.org. The copyright of this article belongs to ESAIM-COC

A model for enhanced and selective transport through biological membranes with alternating pores

We investigate the outflux of ions through the channels in a cell membrane. The channels undergo an open/close cycle according to a periodic schedule. Our study is based both on theoretical considerations relying on homogenization theory, and on Monte Carlo numerical simulations. We examine the onset of a limiting boundary behavior characterized by a constant ratio between the outflux and the local density, in the thermodynamics limit. The focus here is on the issue of selectivity, that is on the different behavior of the ion currents through the channel in the cases of the selected and non-selected species.Comment: arXiv admin note: text overlap with arXiv:1307.418

Labradores y vecinos en la campaña bonaerense a mediados del siglo XIX

Avanzado el siglo XIX y consolidado el modelo agroexportador en la Pampa argentina, la gran estancia, la ganadería extensiva y una distribución inequitativa de la tierra opacaron otras alternativas de desarrollo que se tuvieron en cuenta en los momentos de génesis de la modernización. Este artículo trata de recuperar el rol protagónico que los vecinos tuvieron en los pueblos bonaerenses a mediados del siglo xix, mostrando cómo los gobiernos de la época necesitaron de las redes existentes en la frontera para propiciar la gobernabilidad. A partir de la movilización de labradores de un partido eminentemente triguero, exigiendo el loteo y venta de las tierras públicas a los productores directos, se tratará de poner en evidencia que estadistas de la talla de Mitre y Sarmiento —los primeros presidentes de la Argentina unificada— no solo utilizaron las redes de poder ya existentes sino que evaluaron la posibilidad de considerar que la agricultura, la sociedad campesina y por ende una distribución equitativa de la tierra podían ser alternativas posibles para el desarrollo de la región pampeanaWell into the 19th century, and once the agro-export model had been consolidated in the Argentine pampas, the big estancia (ranch), extensive livestock farming and unequal distribution of land overshadowed other alternatives for development which had been taken into account at the moment of the genesis of modernization. This article aims to describe the leading role that the residents of the province of Buenos Aires played towards the middle of the 19th century, showing how the government needed the existing networks on the borders to build government. Taking as our starting point the mobilization of farmers from a prominent wheatproducing county demanding the subdivision and sale of public lands to the direct producers, we will attempt to demonstrate that important statesmen such as Mitre and Sarmiento —the first presidents of a unified Argentina— not only used these existing networks of power, but also evaluated the possibility of considering that agriculture, rural society and therefore a fair distribution of the land could be a possible alternative to the development of the pampas regio

Social cleavages and the political system in late 19th century Italy

Ausgehend von der Feststellung, daß es nur sehr wenige Studien im Bereich der quantitativen historischen Politikforschung über die Wandlungen des politischen Systems in Italien gibt, untersucht der Autor Wähler, Wahlverhalten, Wahlen, Politiker und das politische System in Italien zwischen 1861 und 1913. Es wird festgestellt, daß die regionalen Unterschiede in Italien einen prägenden Einfluß auf die extrem unterschiedlichen Befunde zu praktisch allen Variablen haben. So reicht die Wahlteilnahme 1861 von über 90 % auf Sizilien bis hinunter zu 20 % in den Städten des Nordens wie Bologna, Florenz, Genua und Mailand. Erklärend ist hier das Phänomen des Patronagesystems, die unterschiedlichen Einflußnahmen sozialer Kontrolle in Stadt und Land. Als weitere Besonderheit des italienischen politischen Systems muß der außergewöhnlich hohe Anteil an Berufspolitikern angesehen werden. Im Zusammenhang damit ist die im Vergleich zu anderen Ländern sehr hohe Verweildauer im Parlament der italienischen Abgeordneten zu sehen. Als wichtiges intervenierendes Phänomen wird die Korruption beschrieben, insbesondere der Stimmenkauf durch Bestechung. Dieses Verhalten war insbesondere in ländlich geprägten Regionen üblich, wo die Stimmen durch kleine Geldzahlungen, warme Mahlzeiten oder einen halben Liter Wein gekauft wurden. Im Italien des ausgehenden 19. Jahrhunderts wird die Bürokratie auf breiter Front von Korruption durchdrungen, ein Prozeß der als "Versüdlichung der Bürokratie" allseits bekannt wurde. Damit erhielten die Angehörigen der oberen Schichten aus dem Mezzogiorno Italiens die Chance, Führungspositionen in der bürgerlichen Gesellschaft des Staates einzunehmen. (ICF

Flux through a time-periodic gate: Monte Carlo test of a homogenization result

We investigate via Monte Carlo numerical simulations and theoretical considerations the outflux of random walkers moving in an interval bounded by an interface exhibiting channels (pores, doors) which undergo an open/close cycle according to a periodic schedule. We examine the onset of a limiting boundary behavior characterized by a constant ratio between the outflux and the local density, in the thermodynamic limit. We compare such a limit with the predictions of a theoretical model already obtained in the literature as the homogenization limit of a suitable diffusion problem