Search results for "SIM"

A microscopic approach to Casimir forces between metal bodies

2014

We consider the Casimir interaction between macroscopic metallic objects in terms of the dispersion interactions (Casimir-Polder and van der Waals) between their constituents. Expressions for two- and three-body dispersion interactions between the microscopic parts of a metal are obtained, both in the retarded and non-retarded limits. They are then used to evaluate two- and three-body contributions of the Casimir force between two flat ideal metallic slabs. Our results show the non-applicability of the Hamaker approximation in this geometry. It is further seen that the three-body contributions give an overall repulsive contribution to the force, which is of the same order of magnitude as th…

Il vuoto: da Galileo al XXI secolo

2009

Electromagnetic field fluctuations near a point-like and an extended field source

2014

We investigate the field fluctuations near a point-like and an extended field source, such as an atom or a polarisable body, and discuss the problem of their singular behaviour at the position of the source. We consider a point-like source interacting with the electromagnetic field, in its dressed ground-state and investigate the local and global properties of the electric and magnetic energy densities in the space around the point-like source, after that the zero-point energy has been subtracted. We show that the assumption of a point-like source leads to a divergence of the renormalized electric and magnetic energy densities at the position of the source. We investigate in detail the math…

Casimir Energies in a One-Dimensional Cavity with a Fluctuating Boundary

2013

We consider a massless scalar field in a one-dimensional cavity with one fixed and one mobile wall. We assume that the mobile wall is also subjected to a harmonic potential, and its mechanical degrees of freedom are treated quantum-mechanically. The wall's position has thus quantum fluctuations around the equilibrium position. The possible motion of the wall makes the cavity length variable, and this gives rise to a wall-field interaction and an effective interaction between the modes of the cavity. We use an effective Hamiltonian, originally introduced by C. K. Law, to describe our system in terms of field modes relative to the equilibrium position of the mobile wall. We obtain by perturba…

Dynamical Casimir-Polder forces between an atom and a conducting wall

2008

Electromagnetic field fluctuations near a dielectric half-space and appearance of surface divergences in the ideal conductor limit

2012

The electromagnetic field fluctuations in the vacuum state are considered in the region external to a half-space filled with a homogeneous non-dissipative dielectric. We discuss the appropriate limits to a real and an ideal metal, focusing on the renormalized field fluctuations (equivalent to energy densities) in the proximity of the dielectric-vacuum interface. We show that, whereas in presence of a real conductor the renormalized field fluctuations are finite in any point of space, surface divergences appear at the interface in the ideal conductor limit. The main features of such divergences are discussed in detail. We point out that the behavior of field fluctuations close to the interfa…

Characterization of fusion from without induced by herpes simplex virus

1991

The process of fusion from without (FFWO) induced by herpes simplex virus (HSV) was analyzed by using various inhibitors and compared to fusion from within (FFWI). The fate of certain elements of the cytoskeleton after FFWO was also investigated. Our experiments demonstrate FFWO as a very suitable system for study of early virus-cell interactions. Zn++ ions proved inhibitory for penetration whilst pretreatment of cells with Ca++ ions before infection enhanced FFWO activity. Dissociation of penetration from the fusion process itself was possible by use of Zn++ ions, low pH-treatment and antiserum on the one hand and N-ethylmaleimide and cytochalasin D on the other. Penetration itself needs o…

Religione e politica in Niccolò Tommaseo

2008

Recensione a: C. Giurintano, Riformismo e liberalismo in Augustin Cochin (1823-1872), Firenze, Centro Editoriale Toscano, 2007

2009

Il lavoro di Claudia Giurintano analizza il pensiero e l’opera di Augustin Cochin, che può considerarsi come uno dei più qualificati rappresentanti del cattolicesimo sociale francese. Attraverso molteplici e documentate comparazioni teoriche, che attestano quanto sia stata capillare la circolazione delle idee nell’Europa ottocentesca, da questo volume su Cochin riceviamo un interessante approfondimento delle trame intellettuali e politiche su cui è stato chiamato a muoversi e a maturare l’incontro dei cattolici con le nuove caratterizzazioni storiche assunte dalla libertà e dalla democrazia.

On Approximation of Entropy Solutions for One System of Nonlinear Hyperbolic Conservation Laws with Impulse Source Terms

2010

We study one class of nonlinear fluid dynamic models with impulse source terms. The model consists of a system of two hyperbolic conservation laws: a nonlinear conservation law for the goods density and a linear evolution equation for the processing rate. We consider the case when influx-rates in the second equation take the form of impulse functions. Using the vanishing viscosity method and the so-called principle of fictitious controls, we show that entropy solutions to the original Cauchy problem can be approximated by optimal solutions of special optimization problems.