Photoemission from non-polar aromatic molecules in the gas and liquid phase.

The photoelectron spectra of both liquid and gas phase aromatic molecules are reported. The spectra were obtained using a 34.1 eV source produced by high harmonic generation and analysed with the help of high-level ab initio simulations using the reflection principle combined with path integral molecular dynamics simulations accounting for nuclear quantum effects for the gas phase. We demonstrate the suitability of three trimethylbenzenes (1,3,5-trimethylbenzene, 1,2,3-trimethylbenzene and 1,2,4-trimethylbenzene) as a solvent for liquid photoelectron spectroscopy of solute species. We also discuss the electrokinetic charging of a non-polar liquid jet.

Laser-Assisted Photoelectric Effect from Liquids.

The laser-assisted photoelectric effect from liquid surfaces is reported for the first time. Photoelectrons generated by 35.6 eV radiation from a liquid microjet of water under vacuum are dressed with a ℏω=1.55 eV laser field. The subsequent redistribution of the photoelectron energies consists in the appearance of sidebands shifted by energies equivalent to ℏω, 2ℏω, and 3ℏω. The response has been modeled to the third order and combined with energy-resolved measurements. This result opens the possibility to investigate the dynamics at surfaces of liquid solutions and provide information about the electron emission process from a liquid.

Harmonium: A pulse preserving source of monochromatic extreme ultraviolet (30-110 eV) radiation for ultrafast photoelectron spectroscopy of liquids.

A tuneable repetition rate extreme ultraviolet source (Harmonium) for time resolved photoelectron spectroscopy of liquids is presented. High harmonic generation produces 30-110 eV photons, with fluxes ranging from ∼2 × 10(11) photons/s at 36 eV to ∼2 × 10(8) photons/s at 100 eV. Four different gratings in a time-preserving grating monochromator provide either high energy resolution (0.2 eV) or high temporal resolution (40 fs) between 30 and 110 eV. Laser assisted photoemission was used to measure the temporal response of the system. Vibrational progressions in gas phase water were measured demonstrating the ∼0.2 eV energy resolution.

Retrospective serological survey on selected viral pathogens in wild boar populations in Germany.

The objective of this study was to retrospectively evaluate the occurrence of porcine parvovirus (PPV), Aujeszky's disease virus (ADV), transmissible gastroenteritis virus (TGEV), porcine respiratory coronavirus (PRCV), porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV) in selected wild boar populations in Germany (n = 1,221). Commercial enzyme linked immunosorbent assay and hemagglutination inhibition tests were used for serological monitoring. The serosurvey revealed seroprevalence rates of 64.28%, 11.26%, 7.87%, 7.84%, 3.82% and 1.59% for PPV, ADV, PRCV, SIV, PRRSV and TGEV, respectively. The seroprevalence rates differed between populations and age classes with the highest number of antibody-positive wild boars in older animals (>1 year old). No antibodies to TGEV were found in Baden-Wuerttemberg and in Mecklenburg-Western Pomerania (investigation period 1997/1998). In addition, sera collected in Mecklenburg-Western Pomerania in 1997/1998 were negative for SIV. Even though the seroprevalence rates established for these viruses, except for PPV, were relatively low, wild boars may act as a reservoir for pathogens and a source of infection for domestic pigs and humans. Based on the epidemiological situation, no risk of a spread of these viruses should emanate from wild boars, neither for wildlife nor for livestock. However, effective and science-based disease monitoring programmes should continuously be carried out in wild boar populations.

Diagnostic procedures after completion of oral immunisation against classical swine fever in wild boar.

The purpose of this paper is to define diagnostic procedures for wild boar after the completion of oral immunisation against classical swine fever (CSF). Epidemiological analysis of CSF in wild boar in Germany demonstrated that it is vital to carry out virological investigations on all animals found dead, sick or involved in traffic accidents. In principle, this should ensure an effective and prompt diagnosis of CSF. In addition, a defined number of wild boar, especially young animals < or = 6 months old, should also be tested for CSF virus to guarantee a high confidence level in the virological monitoring. Which animals should be examined serologically depends on the age class investigated, the season in which vaccination was stopped and the period of time since completion of vaccination. Therefore, different serological procedures have been defined for different situations during the first three years after completion of oral immunisation.

Characterisation of pseudorabies virus isolated from wild boar (Sus scrofa).

Seroepidemiological evidence had suggested that pseudorabies (Aujeszky's disease) virus (PrV) infections occur in the European wild boar population in eastern Germany, although attempts to isolate the causative agent had failed. In 1995 and 1996, five virus isolates were recovered from latently infected wild boar originating from two regions where the disease was endemic. The isolates were identified as PrV by immunofluorescence and neutralisation with specific sera and grouped as PrV type I. Compared with reference strains and PrV isolates obtained from domestic animals in the same region, considerable differences in the DNA patterns were detected. In particular, two additional larger BamHI-DNA fragments migrating in agarose gel electrophoresis between fragments 3 and 4 were observed, accompanied by the loss of fragments 5, 10 and 12. Southern blot hybridisation with fragment-specific DNA probes identified the larger fragments as fusions of BamHI-fragments 5 and 10, and 5 and 12, respectively, due to a loss of a BamHI-site in the inverted repeat regions. This distinctive fragment pattern has so far not been observed in PrV isolates from domestic pigs in Germany.

[Production of maedi-visna virus antigen for the immunodiffusion test and its use for field studies]. / Herstellung von Maedi-Visna-Virusantigen für den Immundiffusionstest und sein Einsatz für Felduntersuchungen.

Using the Maedi-Visna virus strain WLC1 (Weybridge) and different cell lines of sheep plexus chorioideus we were able to establish and improve a production procedure of MV-antigen for use in immunodiffusion assay. Our attention was focused mainly on the efficient virus multiplication in cell cultures and on standardisation of the procedure to find a method keeping the antigen loss as low as possible. Investigations with our antigen in 39 farms of 5 of the former districts in East Germany revealed a seropositive reagent rate between 0 and more than 60%, underlining the need for a complex diagnostic and eradication programme.