Electron shell ionization of atoms with classical, relativistic scattering.

We investigate forward scattering of ionization from neon, argon, and xenon in ultrahigh intensities of 2 × 10(19) W/cm(2). Comparisons between the gases reveal the energy of the outgoing photoelectron determines its momentum, which can be scattered as far forward as 45° from the laser wave vector k(laser) for energies greater than 1 MeV. The shell structure in the atom manifests itself as modulations in the photoelectron yield and the width of the angular distributions. We arrive at an agreement with theory by using an independent electron model for the atom, a dipole approximation for the bound state interaction, and a relativistic, three-dimensional, classical radiation field including the laser magnetic field. The studies provide the atomic physics within plasmas, radiation, and particle acceleration in ultrastrong fields.

Cosmic ray electrons and positrons from supernova explosions of massive stars.

We attribute the recently discovered cosmic ray electron and cosmic ray positron excess components and their cutoffs to the acceleration in the supernova shock in the polar cap of exploding Wolf-Rayet and red supergiant stars. Considering a spherical surface at some radius around such a star, the magnetic field is radial in the polar cap as opposed to most of 4pi (the full solid angle), where the magnetic field is nearly tangential. This difference yields a flatter spectrum, and also an enhanced positron injection for the cosmic rays accelerated in the polar cap. This reasoning naturally explains the observations. Precise spectral measurements will be the test, as this predicts a simple E;{-2} spectrum for the new components in the source, steepened to E;{-3} in observations with an E;{-4} cutoff.

Immunohistological and serological investigations of morbillivirus infection in Black Sea harbour porpoises (Phocoena phocoena).

In the present study the occurrence of morbillivirus infection in harbour porpoises (Phocoena phocoena) from the Black Sea was investigated. Blood and tissue specimens of lung, brain and spleen from 73 stranded or by-caught harbour porpoises derived from the three Black Sea subregions such as Bulgaria, Georgia and Ukraine were collected between 1997 and 1999 and processed for histology, immunohistochemistry and serology. Age determination was performed according to dental growth layers and body length. The age of the investigated population ranged from neonates to a 12-year-old animal. Morbillivirus-specific neutralizing antibodies were detected in 53% of harbour porpoises. Generally, titres were very low and ranged from 20 to 270. There was no correlation between age, geographical origin and titre levels. The most common histological finding (97%) consisted of a mild to severe granulomatous bronchopneumonia due to lung worm infection. There were no changes indicative of a morbillivirus infection. Using immunohistology none of the animals were positive for morbillivirus antigen. However, the serological data are suggestive of a continuously circulating morbillivirus among harbour porpoises from the Black Sea indicating that harbour porpoises may serve as carriers for fatal diseases in susceptible cetacean species.

Total and organic mercury in the Black Sea harbour porpoise Phocoena phocoena relicta.

This paper reports on mercury (Hg) concentrations in different tissues (liver, muscle, kidney, blubber and brain) of harbour porpoises Phocoena phocoena found dead in the Black Sea between 1997 and 1999, mainly bycaught in fishing nets (n = 79). Total Hg and organic Hg (MeHg) were determined. The main factor affecting Hg accumulation was, as expected, age, with MeHg concentration increasing with age. Accumulation of high concentrations of inorganic Hg in the liver was probably due to a slow demethylation process implying the formation of tiemannite (HgSe). In older adults, liver concentrations reached 35 microg g(-1) dry weight ('ppm') total Hg and 3 microg g(-1) dw MeHg. A geographical comparison with existing data from other regions showed a generally low Hg contamination of Black Sea porpoises, one order of magnitude lower than, e.g. in the North Sea.