[en] A model for the biological effects of the energy deposited by ion beams on irradiated tissues is presented. The relevant parameters are the fractions of undamaged cells (where of course the definition of damaged cell depends on the biological end point under consideration, e.g. surviving cells) after the sensitive target of the cells has been traversed by any given number of ionising particles. The experimental parameters of the dose response curves offer a way to determine those of the model. The model can be formulated both for the simpler case of cells traversed by only one radiation quality, i.e. by a monoenergetic beam of a given ion, and for the general case of irradiation by a mixed field. A possible application in experimental data analysis is presented. (author)

[en] It is suggested that a fast kinetic mode should be observable in a whole class of disparate mass fluid mixtures, such as gaseous He-Xe, by neutron scattering experiments, at not too high densities and Xe concentrations

[en] In this paper we briefly review some of the approaches that have recently been developed for hadron therapy applications in order to build a model for the evaluation of biological effects in mixed radiation fields. We consider in particular: i) the microdosimetric approach, ii) the approaches based on amorphous track models; iii) the semi-empirical approach; iv) the '3D track structure / complex lesions' model. We then argue about their possible use to predict biological effects in manned space missions, and about some specific aspects where further research is strongly needed. (author)

[en] Use of cellular systems capable of undergoing in vitro differentiation can give useful information on the basic mechanisms of cellular radiation sensitivity. During differentiation the cellular organisation, including the nuclear structure and the intracellular concentration of several compounds and enzymes change drastically. Accordingly, radiation response to ionising radiation is also expected to change. The human proerythroblastoid cell line K562 can be induced to pseudoerythroid differentiation. This process has been characterised and studies have been carried out on DNA single strand break and double strand break induction and repair before and after differentiation commitment. Rejoining studies have been performed for both types of damage and correct double strand break rejoining has been also measured in particular genomic locations. An overview is presented of these results together with preliminary data recently obtained on radiation induced DNA fragmentation as a function of radiation quality. (author)

[en] Kinetic sound is predicted in dilute disparate-mass binary gas mixtures, propagating exclusively in the light compound and much faster than ordinary sound. It should be detectable by light-scattering experiments, as an extended shoulder in the scattering cross section for large frequencies. As an example, H₂-Ar mixtures are discussed

[en] Outside the magnetic field of the Earth, high energy heavy ions constitute a relevant part of the biologically significant dose to astronauts during the very long travels through space. The typical pattern of energy deposition in the matter by heavy ions on the microscopic scale is believed to produce spatially correlated damage in the DNA which is critical for radiobiological effects. We have investigated the influence of a lucite shielding on the initial production of very small DNA fragments in human fibroblasts irradiated with 1 GeV/u iron (Fe) ions. We also used small gamma, Greek-rays as reference radiation. Our results show: (1) a lower effect per incident ion when the shielding is used; (2) an higher DNA Double Strand Breaks (DSB) induction by Fe ions than by small gamma, Greek-rays in the size range 123 kbp; (3) a non-random DNA DSB induction by Fe ions

[en] We suggest a mechanism allowing the introduction of a small violation of the Pauli exclusion principle. Within this framework, we compute the grand partition function for a free-electron gas in a metal. We discuss the physical implications of our results and infer an upper bound on the violation parameter

No abstract available

[en] We propose a new parametrization of the quark mixing matrix (the Kobayashi-Maskawa matrix) in terms of four independent moduli of its matrix elements: chemical bondV/sub us/chemical bond, chemical bondV/sub cb/chemical bond, chemical bondV/sub td/chemical bond, and chemical bondV/sub ub/chemical bond/chemical bondV/sub cb/chemical bond. Based on this convenient parametrization, we study the constraints on the top-quark mass and the quark mixing elements chemical bondV/sub ij/chemical bond from the recent measurement of ε'/ε, the ARGUS result on B/sub d/⁰-B-bar d⁰ mixing, the ratio chemical bondV/sub ub/chemical bond/chemical bondV/sub cb/chemical bond, and the mixing parameter ε in the K⁰-bar-K⁰ system taking into account all the uncertainties in the input

[en] The calculations and the results that predicted a fast-sound mode in low- as well as high-density binary fluid mixtures are presented in detail. Kinetic theory was used, which allowed a detailed discussion of the microscopic dynamics of the fluid in terms of eigenmodes. The Bhatnagar-Gross-Krook approximation method extended to binary mixtures was employed to solve the appropriate kinetic equation and to obtain approximate eigenmodes of the mixture. The fast-sound mode appears far beyond the hydrodynamic regime as either an extension to higher wave numbers of the hydrodynamic sound eigenmode or as a kinetic eigenmode. Some recent and possible future experiments are discussed