Development of the neotropical catfish Rhamdia quelen (Siluriformes, Heptapteridae) incubated in different temperature regimes.

The developmental stages for the embryonic and larval periods of the silver catfish (Rhamdia quelen) kept at different temperatures (21, 24, 27 and 30 degrees C) are described. Fish were analysed under light and scanning electron microscopy. For embryonic development, we described 25 stages, which were grouped into seven periods named zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatching periods.

Fast ternary and quaternary breakup of the 197Au + 197Au system in collisions at 15 MeV/nucleon.

A new reaction mechanism of violent reseparation of a heavy nucleus-nucleus system, 197Au + 197Au, into three or four massive fragments in collisions at 15 MeV/nucleon has been observed. After reseparation, the fragments are almost exactly aligned, thus showing a very short time scale of the reseparation process, of about 70-80 fm/c.

Isospin dependence of incomplete fusion reactions at 25 MeV/nucleon.

40Ca+;{40,48}Ca,46Ti reactions at 25 MeV/nucleon have been studied using the 4pi CHIMERA detector. An isospin effect on the competition between fusionlike and binarylike reaction mechanisms has been observed. The probability of producing a heavy residue is lower in the case of N approximately Z colliding systems as compared to the case of reactions induced on the neutron rich 48Ca target.

Dielectron production in 12C+12C collisions at 2A GeV with the HADES spectrometer.

The invariant-mass spectrum of e+e- pairs produced in 12C+12C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the pi(0)-Dalitz to the rho/omega invariant-mass region. Dalitz decays of pi(0) and eta account for all the yield up to 0.

Nuclear detecting systems at LNL and LNS: foreseen experiments to provide basic data for heavy-ion risk assessment.

The use of existing detecting systems developed for nuclear physics studies allows collecting data on particle and ion production cross-sections in reactions induced by Oxygen and Carbon beams, of interest for hadrontherapy and heavy-ion risk assessment. The MULTICS and GARFIELD apparatus, together with the foreseen experiments, are reviewed.

Strong enhancement of extremely energetic proton production in central heavy ion collisions at intermediate energy.

The energetic proton emission has been investigated as a function of the reaction centrality for the system (58)Ni + (58)Ni at 30A MeV. Extremely energetic protons (E(NN)(p) > or = 130 MeV) were measured and their multiplicity is found to increase almost quadratically with the number of participant nucleons, thus indicating the onset of a mechanism beyond one- and two-body dynamics.