Neutrinoless double-beta decay search with CUORE and CUORE-0 experiments

The Cryogenic Underground Observatory for Rare Events (CUORE) is an upcoming experiment designed to search for the neutrinoless double-beta decays. Observation of the process would unambiguously establish that neutrinos are Majorana particles and provide information on their absolute mass scale hierarchy. CUORE is now under construction and will consist of an array of 988 TeO2 crystal bolometers operated at 10 mK, but the first tower (CUORE-0) is already taking data. The experimental techniques used will be presented as well as the preliminary CUORE-0 results. The current status of the full-mass experiment and its expected sensitivity will then be discussed

A short elementary proof of the Gearhart–Prüss theorem for bounded semigroups

We present a short elementary proof of the Gearhart–Prüss theorem for bounded C0-semigroups on Hilbert spaces

Benjamin–Bona–Mahony Equations with Memory and Rayleigh Friction

International audienceThis paper is concerned with the integrodifferential Benjamin-Bona-Mahony equation : u(t) - u(txx) + alpha u - integral(infinity)(0)g(s)u(xx)(t - s)ds + (f(u))(x) = hcomplemented with Dirichlet boundary conditions, in the presence of a possibly large external force h. The nonlinearity f is allowed to exhibit a superquadratic growth, and the dissipation is due to the simultaneous interaction between the nonlocal memory term and the Rayleigh friction. The existence of regular global and exponential attractors of finite fractal dimension is show

A note on the Moore–Gibson–Thompson equation with memory of type II

We consider the Moore–Gibson–Thompson equation with memory of type II ∂tttu(t)+α∂ttu(t)+βA∂tu(t)+γAu(t)-∫0tg(t-s)A∂tu(s)ds=0where A is a strictly positive selfadjoint linear operator (bounded or unbounded) and α, β, γ\u3e 0 satisfy the relation γ≤ αβ. First, we prove well-posedness of finite energy solutions, without requiring any restriction on the total mass ϱ of g. This extends previous results in the literature, where such a restriction was imposed. Second, we address an open question within the context of longtime behavior of solutions. We show that an “overdamping” in the memory term can destabilize the originally stable dynamics. In fact, it is always possible to find memory kernels g, complying with the usual mass restriction ϱ\u3c β, such that the equation admits solutions with energy growing exponentially fast, even in the regime γ\u3c αβ where the corresponding model without memory is exponentially stable. In particular, this provides an answer to a question recently raised in the literature

Spectral analysis and stability of the Moore-Gibson-Thompson-Fourier model

We consider the linear evolution system \begin{cases} u_{ttt}+\alpha u_{tt} + \beta \Delta^2 u_t + \gamma \Delta^2 u =- \eta \Delta \theta \\ \noalign{\vskip1mm} \theta_t - \kappa \Delta \theta = \eta \Delta u_{tt} + \alpha\eta \Delta u_t \end{cases} describing the dynamics of a thermoviscoelastic plate of MGT type with Fourier heat conduction. The focus is the analysis of the energy transfer between the two equations, particularly when the first one stands in the supercritical regime, and exhibits an antidissipative character. The principal actor becomes then the coupling constant $\eta$, ruling the competition between the Fourier damping and the MGT antidamping. Indeed, we will show that a sufficiently large $\eta$ is always able to stabilize the system exponentially fast. One of the features of this model is the presence of the bilaplacian in the first equation. With respect to the analogous model with the Laplacian, this introduces some differences in the mathematical approach. From the one side, the energy estimate method does not seem to apply in a direct way, from the other side, there is a gain of regularity allowing to rely on analytic semigroup techniques

Optical Limiting of Carbon Nanohorn-Based Aqueous Nanofluids: A Systematic Study

Nowadays, the use of lasers has become commonplace in everyday life, and laser protection has become an important field of scientific investigation, as well as a security issue. In this context, optical limiters are receiving increasing attention. This work focuses on the identification of the significant parameters affecting optical limiting properties of aqueous suspensions of pristine single-wall carbon nanohorns. The study is carried out on the spectral range, spanning from ultraviolet to near-infrared (355, 532 and 1064 nm). Optical nonlinear properties are systematically investigated as a function of nanohorn morphology, concentration, dimensions of aggregates, sample preparation procedure, nanostructure oxidation and the presence and concentration of surfactants to identify the role of each parameter in the nonlinear optical behavior of colloids. The size and morphology of individual nanoparticles were identified to primarily determine optical limiting. A cluster size effect was also demonstrated, showing more effective optical limiting in larger aggregates. Most importantly, we describe an original approach to identify the dominant nonlinear mechanism. This method requires simple transmittance measurements and a fitting procedure. In our suspensions, nonlinearity was identified to be of electronic origin at a 532 nm wavelength, while at 355 nm, it was found in the generation of bubbles