Reaction mechanisms involved in the production of neutron-rich isotopes

The reaction mechanisms best suited for the production of neutron-rich nuclei, fragmentation and fission, are discussed. Measurements of the production cross sections of reaction residues together with model calculations allow to conclude about the expected production rates of neutron-rich isotopes in future facilities.Comment: 9 pages, 8 figures Proceedings of the Third International Conference on Fission and Properties of Neutron-Rich Nuclei November 3-9, 2002, Sanibel Island, Florida, US

Experimental Indications for the Response of the Spectators to the Participant Blast

Precise momentum distributions of identified projectile fragments, formed in the reactions 238U + Pb and 238U + Ti at 1 A GeV, are measured with a high-resolution magnetic spectrometer. With increasing mass loss, the velocities first decrease as expected from previously established systematics, then level off, and finally increase again. Light fragments are on the average even faster than the projectiles. This finding is interpreted as the response of the spectators to the participant blast. The re-acceleration of projectile spectators is sensitive to the nuclear mean field and provides a new tool for investigating the equation of state of nuclear matter.Comment: 7 pages, 3 figures, background information on http://www-wnt.gsi.de/kschmidt

Dispersion of longitudinal momentum distributions induced in fragmentation reactions

On the basis of systematic measurements of fragmentation reactions, which provide a detailed overview on the velocity distributions of residual nuclei, an improved description of the kinematical properties of the fragmentation residues is established. This work is dedicated to the fluctuations of their momentum distributions. In contrast to previous investigations, limited to close-to-projectile fragments, we extended our study to the entire production range, down to the lightest observed fragments. In this context, beside the contribution of abrasion and evaporation processes, we considered the effect of the thermal break-up on the width of the momentum distributions. Using approximated theoretical descriptions of the different reaction stages, a new analytical formula for the variance of the momentum distribution is derived, which is well adapted to technical applications.Comment: 14 pages, 3 figures, background info. at http://www-wnt.gsi.de/charms

Biological aspects of mTOR in leukemia

The mammalian target of rapamycin (mTOR) is a central processor of intra-and extracellular signals, regulating many fundamental cellular processes such as metabolism, growth, proliferation, and survival. Strong evidences have indicated that mTOR dysregulation is deeply implicated in leukemogenesis. This has led to growing interest in the development of modulators of its activity for leukemia treatment. This review intends to provide an outline of the principal biological and molecular functions of mTOR. We summarize the current understanding of how mTOR interacts with microRNAs, with components of cell metabolism, and with controllers of apoptotic machinery. Lastly, from a clinical/translational perspective, we recapitulate the therapeutic results in leukemia, obtained by using mTOR inhibitors as single agents and in combination with other compounds

Origin of the even-odd effect in the yields from high-energy reactions

The analysis of experimental production cross-sections of the light products of several nuclear reactions at high energy, measured at the FRS, GSI Darmstadt, revealed a very strong and complex even-odd staggering. The origin of this effect is related to the condensation process of heated nuclear matter while cooling down in the last evaporation step. The characteristics of the staggering correlate strongly with the lowest particle separation energy of the final experimentally observed nuclei. The study confirms the important role of the deexcitation process in fragmentation reactions, and indicates that sequential decay strongly influences the yields of light fragments, which are often used to extract information on the nature of nuclear reactions at high energies

Intervento di sismica passiva all'Isola di Stromboli durante l'eruzione del Dicembre 1985

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Permeability characterization of stitched carbon fiber preforms by fiber optic sensors

The in-plane and through thickness permeability of unidirectional stitched carbon fiber preforms have been determined through vacuum infusion tests. The impregnation of various dry preforms with different stitching characteristics has been monitored by fiber optic sensors that have been stitched together with the dry tow to manufacture the dry preform. The experimental infusion times have been fitted by a numerical procedure based on Finite Element (FE) processing simulations. A good agreement between the numerical and experimental infusion times has been found demonstrating the potentiality of the fiber sensor system as suitable tool to evaluate impregnation times and permeability characteristics