A semilinear problem with a W^{1,1}_0 solution

We study a degenerate elliptic equation, proving the existence of a W^{1,1}_0 distributional solution

The taxation of motor fuel : international comparison

This paper assesses whether the level of taxation of motor fuel is broadly appropriate in a group of countries (OECD, BRICs and South Africa) accounting for more than 80 percent of world greenhouse gas emissions. The analysis deals with emissions from oil combustion in transport, which account for about 40 percent of carbon dioxide emissions. In the benchmark specification, six countries (responsible, in turn, for more than 40 percent of worldwide motor-fuel greenhouse gas world emissions) would be undertaxing motor fuel. The authors evaluate the sensitivity of the results to the values of the elasticities and externalities that used in the analysis. They find that varying the values of these parameters (within the level of uncertainty reasonably associated with them) significantly affects the results. This implies that, while informative, the results must be taken as indicative. Further analysis for a particular country must rely on a well-informed choice for the values of the country-specific parameters.Transport Economics Policy&Planning,Energy Production and Transportation,Taxation&Subsidies,Climate Change Mitigation and Green House Gases,Climate Change Economics

Existence results for a Cauchy-Dirichlet parabolic problem with a repulsive gradient term

We study the existence of solutions of a nonlinear parabolic problem of Cauchy-Dirichlet type having a lower order term which depends on the gradient. The model we have in mind is the following: \begin{cases}\begin{split} & u_t-\text{div}(A(t,x)\nabla u|\nabla u|^{p-2})=\gamma |\nabla u|^q+f(t,x) &\qquad\text{in } Q_T,\\ & u=0 &\qquad\text{on }(0,T)\times \partial \Omega,\\ & u(0,x)=u_0(x) &\qquad\text{in } \Omega, \end{split}\end{cases} where $Q_T=(0,T)\times \Omega$, $\Omega$ is a bounded domain of $\mathrm{R}^N$, $N\ge 2$, $1<p<N$, the matrix $A(t,x)$ is coercive and with measurable bounded coefficients, the r.h.s. growth rate satisfies the superlinearity condition $$\max\left\{\frac{p}{2},\frac{p(N+1)-N}{N+2}\right\}<q<p$$ and the initial datum $u_0$ is an unbounded function belonging to a suitable Lebesgue space $L^\sigma(\Omega)$. We point out that, once we have fixed $q$, there exists a link between this growth rate and exponent $\sigma=\sigma(q,N,p)$ which allows one to have (or not) an existence result. Moreover, the value of $q$ deeply influences the notion of solution we can ask for. The sublinear growth case with $$0<q\le\frac{p}{2}$$ is dealt at the end of the paper for what concerns small value of $p$, namely $1<p<2$

The role of interplay between coefficients in the GG-convergence of some elliptic equations

We study the behavior of the solutions $u$ of the linear Dirichlet problems $- \mathrm{div} (M(x) \nabla u) + a(x) u = f(x)$ with respect to perturbations of the matrix $M(x)$ (with respect to the $G$-convergence) and with respect to perturbations of the nonnegative coefficient $a(x)$ and of the right hand side $f(x)$ satisfying the condition $|f (x)| \leq Q \, a (x)$

Existence and multiplicity for elliptic problems with quadratic growth in the gradient

We show that a class of divergence-form elliptic problems with quadratic growth in the gradient and non-coercive zero order terms are solvable, under essentially optimal hypotheses on the coefficients in the equation. In addition, we prove that the solutions are in general not unique. The case where the zero order term has the opposite sign was already intensively studied and the uniqueness is the rule.Comment: To appear in Comm. PD

Diffeomorphism-invariant properties for quasi-linear elliptic operators

For quasi-linear elliptic equations we detect relevant properties which remain invariant under the action of a suitable class of diffeomorphisms. This yields a connection between existence theories for equations with degenerate and non-degenerate coerciveness.Comment: 16 page

Computational Investigation of Nanoparticles at the Biointerface

Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions which are able to provide solutions to both theoretical and practical problems in areas such as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles (AuNPs) with core diameters in the rage 1 1210 nm have emerged as a powerful class of materials for a variety of biomedical applications. The utility of AuNPs is enhanced by our ability in tuning their surface properties by grafting multiple ligand species able to self-assemble in mixed-monolayers. Thus, identification of molecular designing rules is essential to achieve a precise control of specifically patterned monolayer protected nanoparticles for an intended biological outcome. In this thesis are described the evidences of our investigation of the self-organization of different mixtures of immiscible ligands on a spherical gold surface. The evaluation of the role of some critical parameter such as core dimension, different chemistry and relative ligand length and ratio as well as solvent was the starting point to develop a standard procedure to tune the self-assembled monolayer (SAM) morphology. Studies of the morphology of these mixed monolayers were carried out using an in-silico approach based on multiscale molecular simulations. Then, combining theory and experiments, we investigated the role of ligand arrangement and composition on the interaction with model lipid bilayer (either simple and complex) and with cells of these monolayer protected NPs. In-silico models were then employed to study the binding of patterned AuNps with human serum albumin (HSA), uncovering the impact of the monolayer morphologies on protein-NP interfaces. Laslty, a third kind of biointerface was taken into account and the supramolecular binding of small molecules, toward mixed/homoligand shells was disclosed

new perspectives in emergency mapping

AbstractIn recent years, growing attention is paid to remote sensing when used for disaster management applications. This is essentially due to the large variety of remotely acquired imagery availa..

Participación y Democratización: Demandas estudiantiles

Proyecto de nuevo Estatuto .- La Federación de Estudiantesfundamenta su petición para aumentar la representación estudiantil enel Consejo Universitario, con plenos derechos, al Presidente de la FECH y cuatro delegados. 57a. or. 13-12-67