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

Well-posedness for a modified bidomain model describing bioelectric activity in damaged heart tissues

We prove the existence and the uniqueness of a solution for a modified bidomain model, describing the electrical behaviour of the cardiac tissue in pathological situations. The main idea is to reduce the problem to an abstract parabolic setting, which requires to introduce several auxiliary differential systems and a non-standard bilinear form. The main difficulties are due to the degeneracy of the bidomain system and to its non-standard coupling with the diffusion equation

Asymptotic analysis for non-local problems in composites with different imperfect contact conditions

We consider a composite material made up of a hosting medium containing an \eps-periodic array of perfect thermal conductors. Comparing with the previous contributions in the literature, in the present paper, the inclusions are completely disconnected and form two families with dissimilar physical behaviour. More specifically, the imperfect contact between the hosting medium and the inclusions obeys two different laws, according to the two different types of inclusions. The contact conditions involve the small parameter \eps and two positive constants \contuno,\contdue. We investigate the homogenization limit \eps\to 0 and the limits for \contuno,\contdue going to $0$ or $+\infty$, taken in any order, with the aim to find out the cases in which the two limits commute

Large Time Behavior of Solutions to the Neumann Problem for a Quasilinear Second Order Degenerate Parabolic Equation in Domains with Noncompact Boundary

AbstractWe investigate the optimal rate of stabilization at large time of a solution to the Neumann problemut=∑i=1N∂∂xi(ai(x, t, ∇u))−b(x, t, u),inΩ×(0, T),T>0∑i=1Nai(x, t, ∇u)ni=0,on∂Ω×(0, T)u(x, 0)=u0(x)x∈Ω,u0(x)⩾0inΩ,where Ω⊂RN, N⩾2, is an unbounded domain with sufficiently smooth noncompact boundary ∂Ω satisfying certain isoperimetrical inequality and n=(ni) is the outward normal to ∂Ω

A degenerate pseudo-parabolic equation with memory

We prove the existence and uniqueness for a degenerate pseudo-parabolic problem with memory. This kind of problem arises in the study of the homogenization of some differential systems involving the Laplace-Beltrami operator and describes the effective behaviour of the electrical conduction in some composite materials

Compact and explicit physical model for lateral metal-oxide-semiconductor field-effect transistor with nanoelectromechanical system based resonant gate

We propose a simple analytical model of a metal-oxide-semiconductor field-effect transistor with a lateral resonant gate based on the coupled electromechanical equations, which are self-consistently solved in time. All charge densities according to the mechanical oscillations are evaluated. The only input parameters are the physical characteristics of the device. No extra mathematical parameters are used to fit the experimental results. Theoretical results are in good agreement with the experimental data in static and dynamic operation. Our model is comprehensive and may be suitable for any electromechanical device based on the field-effect transduction

Resisting austerity in the era of COVID-19.:Between nationwide mobilisation and decentralised organising in Ecuador

Since 2017, the return of a neoliberal government in Ecuador has been characterized by austerity measures designed to lower state debt, particularly through cuts to social and environmental programs and the privatisation of state institutions. These policies have worsened ongoing economic and environmental crises suffered by the country’s poor, leading to massive protests in October 2019, which temporarily blocked further austerity measures. Yet, in subsequent months, the COVID-19 emergency enabled the government to move forward with neoliberal reforms and with policies promoting the expansion of extractive frontiers and the corporate food system. In this chapter, we examine decentralised organising among anti-neoliberal movements during the pandemic, particularly anti-extractivist and peasant agro-ecological collectives. We confirm prior findings regarding austerity that qualify it as a strategy not only to reduce state expenditure, but also to privately appropriate the commons, actively redirecting wealth to capital. Our research highlights that, in a context where mass protests are hindered by the pandemic, anti-neoliberal resistance in Ecuador operates in flexible articulations or assemblages that respond to shifting contexts. In 2019, marginalized sectors converged on urban political centres, concentrating a popular mass to pressure the central government and later, during COVID-19, local organisations advanced forms of decentralised resistance across the country, constructing or expanding solidarity networks, using legal and digital systems, and mobilizing alliances with local governments. Thus, subaltern anti-neoliberal movements continued to advance a politics of solidarity across changing contexts by flexibly articulating organisationally and tactically