Anion emission from water molecules colliding with positive ions: Identification of binary and many-body processes

It is shown that negative ions are ejected from gas-phase water molecules when bombarded with positive ions at keV energies typical of solar-wind velocities. This finding is relevant for studies of planetary and cometary atmospheres, as well as for radiolysis and radiobiology. Emission of both H- and heavier (O- and OH-) anions, with a larger yield for H-, was observed in 6.6-keV 16O+ + H2O collisions. The ex-perimental setup allowed separate identification of anions formed in collisions with many-body dynamics from those created in hard, binary collisions. Most of the ani-ons are emitted with low kinetic energy due to many-body processes. Model calcu-lations show that both nucleus-nucleus interactions and electronic excitations con-tribute to the observed large anion emission yield.Comment: 5 pages, 4 figure

Ionization of small molecules induced byH+, He+, andN+projectiles: Comparison of experiment with quantum and classical calculations

We report the energy and angular distribution of ejected electrons from CH$_4$ and H$_{2}$O molecules impacted by 1 MeV H$^+$, He$^+$ and 650 keV N$^+$ ions. Spectra were measured at different observation angles, from 2 eV to 2000 eV. The obtained absolute double-differential-electron-emission cross sections (DDCS) were compared with the results of CTMC and CDW-EIS calculations. For the bare H+ projectile both theories show remarkable agreement with the experiment at all observed angles and energies. The CTMC results are in similarly good agreement with the DDCS spectra obtained for impact by dressed He$^+$ and N$^+$ ions, where screening effects and electron loss from the projectile gain importance. The CDW-EIS calculations slightly overestimate the electron loss for 1 MeV He$^+$ impact, and overestimate both the target and projectile ionization at low emitted electron energies for 650 keV N$^+$ impact. The contribution of multiple electron scattering by the projectile and target centers (Fermi-shuttle) dominates the N$^+$-impact spectra at higher electron energies, and it is well reproduced by the non-perturbative CTMC calculations. The contributions of different processes in medium velocity collisions of dressed ions with molecules are determined

Performance of the DNA-citoliq liquid-based cytology system compared with conventional smears

To evaluate the performance of a new, manual, simplified liquid-based system, DNA-Citoliq (Digene Brasil), employed under routine conditions as compared to conventional smears collected from six collaborating private laboratories. Methods: A panel of cytopathologists, who served as the gold standard diagnosis, adjudicated discordant opinions. Results: Of 3206 pairs of slides considered valid for comparison, there were 3008 in full agreement (93.8%), 112 (3.5%) with one diagnostic category discrepancies, and 86 (2.7%) discordant cases. Among the 288 borderline+ by either method, DNA-Citoliq detected abnormalities in 243 (84.4%), and conventional smears (CS) detected abnormalities in 178 (61.8%) (McNemar test, P < 0.000), a 36.5% increased detection of borderline+ cases. Conclusions: For mild dyskaryosis, DNA-Citoliq detected 176 cases and CS 125 cases (McNemar test, P < 0.000); and for moderate+severe dyskaryosis 66 versus 32 cases respectively (McNemar test, P < 0.000)