This paper is concerned with the study of one-body dissipation effects in idealized models resembling a nucleus. In particular, we study the quantum mechanics of a free particle that collides elastically with the slowly moving walls of a Bunimovich stadium billiard. Our results are twofold. First, we develop a method to solve in a simple way the quantum mechanical evolution of planar billiards with moving walls. The formalism is based on the scaling method [1] which enables the resolution of the problem in terms of quantities defined over the boundary of the billiard.The second result is related to the quantum aspects of dissipation in systems

We investigate the spin accumulation effect in eccentric semiconductor multichannel rings with Rashba spin-orbit interaction and threaded by a magnetic flux. Due to the finite eccentricity, the spin polarization induced at the borders of the sample is anisotropic and exhibits different patterns and intensities at specific angular directions. This effect, reminiscent of the spin polarization drift induced by the application of an in plane electric field, could be used to manipulate and functionalize the spin polarization in electronic nanorings. PACS numbers: 71.70.Di,71.70.Ej, The spin manipulation and detection in all electrical devices have been the subjects of an impressive amount of research in the last years 1 . In particular semiconductors in which the spin orbit (SO) interaction plays a significant role, are the main candidates to accomplish such challenges.Among them, ring shaped geometries are particularly attractive to analize different interference phenomena in the presence of SO effects. As an example, Aharonov Bohm (AB) rings with uniform SO interaction have been proposed as spin interference devices 2 to explore the non trivial spin dependent Aharonov-Casher (AC) phase 3,4,5 . Indeed, in recent years the AC effect has been measured in a series of transport experiments on AB conductance oscillations performed in semiconductor rings, for different intensities of the SO interaction 6,7,8,9 . So far most of the theoretical analysis of SO effects in quantum rings have been restricted to 1D geometries 10,11,12,13,14,15 . However realistic rings have a multichannel nature and many interesting phenomena rely on this fact. As an example, in Ref. 16 it was shown that in a AB multichannel ring with Rashba SO coupling 17 , a spin accumulation effect develops at the borders of the sample.Eventhough for an even number of electrons, a finite spin polarization in the direction perpendicular to the plane of the ring is generated and can be controlled with the magnetic flux. This phenomena, although sharing some analogies with the intrinsic Spin Hall Effect (SHE) studied in bar or strip geometries designed on 2DEG 18,19,20 , does not require neither external currents nor electric fields or voltage drops applied 21,22 .Actually in real semiconductor quantum rings (QRs) imperfections of the structure often occurs. Micrograph views of GaAs QRs suggests that real rings may present some degree of eccentricity 23 . In addition, recent advances in oxidation lithography enables the fabrication of semiconductor QRs 24 in which non perfect symmetric structures can be constructed.The effect of a finite eccentricity has been considered in previous studies of energy spectrum and electric polarization in QRs 25,26 . However these works have not taken into account the SO interaction, which is particularly strong in most of the QRs heterostructures.The goal of the present work is to show that by a combined effect of the Rashba SO interaction and the finite eccentricity, the spin accumulation develops anisotropic patterns along th...