Biomedical subjects

A Scardicchio

Publications and source records attributed to A Scardicchio.

6 recordsLinked to original sources

PubMed2006

Casimir Interaction between a plate and a cylinder.

We find the exact Casimir force between a plate and a cylinder, a geometry intermediate between parallel plates, where the force is known exactly, and the plate sphere, where it is known at large separations. The force has an unexpectedly weak decay approximately L/[H3 ln(H/R)] at large plate-cylinder separations H (L and R are the cylinder length and radius), due to transverse magnetic modes. Path integral quantization with a partial wave expansion additionally gives a qualitative difference for the density of states of electric and magnetic modes, and corrections at finite temperatures.

Journal Article↗

PubMed2005

Attractive Casimir forces in a closed geometry.

We study the Casimir force acting on a conducting piston with arbitrary cross section. We find the exact solution for a rectangular cross section and the first three terms in the asymptotic expansion for small height to width ratio when the cross section is arbitrary. Though weakened by the presence of the walls, the Casimir force turns out to be always attractive. Claims of repulsive Casimir forces for related configurations, like the cube, are invalidated by cutoff dependence.

Journal Article↗

PubMed2004

Casimir effect and geometric optics.

We propose a new approach to the Casimir effect based on classical ray optics. We define and compute the contribution of classical optical paths to the Casimir force between rigid bodies. We reproduce the standard result for parallel plates and agree over a wide range of parameters with a recent numerical treatment of the sphere and plate with Dirichlet boundary conditions. Our approach improves upon the proximity force approximation. It can be generalized easily to other geometries, other boundary conditions, to the computation of Casimir energy densities, and to many other situations.

Journal Article↗

PubMed2003

Fractal entropy of a chain of nonlinear oscillators.

We study the time evolution of a chain of nonlinear oscillators. We focus on the fractal features of the spectral entropy and analyze its characteristic intermediate time scales as a function of the nonlinear coupling. A Brownian motion is recognized with an analytic power-law dependence of its diffusion coefficient on the coupling.

Journal Article↗

PubMed2002

Slow relaxation, confinement, and solitons.

Millisecond crystal relaxation has been used to explain anomalous decay in doped alkali halides. We attribute this slowness to Fermi-Pasta-Ulam solitons. Our model exhibits confinement of mechanical energy released by excitation. Extending the model to long times is justified by its relation to solitons, excitations previously proposed to occur in alkali halides. Soliton damping and observation are also discussed.

Journal Article↗

PubMedDate not supplied

[Diaphragmatic trauma: retrospective analysis of 25 patients].

Traumatic diaphragmatic injuries are increasing and they must be considered in every thoraco-abdominal trauma. The Authors carried out a retrospective analysis of 25 cases, whose diagnosis was often difficult due to the predominant clinical effects of associated injuries. All patients underwent surgical operation with laparotomy to achieve reduction of herniated viscera and repair of the diaphragmatic lesion.

Adolescent↗