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Cultural, morphologic, and biochemical characteristics of previously unreported taxa isolated from poultry and tentatively assigned to genus Actinobacillus Brumpt 1910 were compared to those of Actinobacillus lignieresii, A equuli, A. seminis, A. suis, avian haemolytic Actinobacillus sp., A.salpingitidis, avian Pasteurella haemolytica-like strains, P haemolytica biovar T, P, ureae. P. multocida, P. pneumotropica, P. gallinarum and P. anatipestifer. Evidence as obtained to indicate that taxon 1--3 was closely related to genus Actinobacillus Brumpt 1910, but sufficiently different from established species within that genus to constitute new distinct species. Taxon 4 had the cultural and biochemical characters of strains previously described by Clark and Godfrey. Strains designated P haemolytica-like could not be separated from A. salpingitidis on the basis of phenotypical characters. The final taxonomical position of taxon 1-4 in addition to strains designated avian haemolytic Actinobacillus sp. and P. haemolytica-like, however, has to await further taxonomical investigations including determination of mol % G + C in DNA and DNA hybridization, for which reason species names have been omitted.

Salmonella enterica serovar berta was isolated for the first time in Denmark in October 1984. This serovar has subsequently become endemic in the broiler industry. Plasmid profile analysis of 610 strains of S. berta isolated from broilers and broiler parent stock in the period October 1984 to July 1989 showed that plasmids were present in 85.7% of strains investigated, with a mean of 1.8 plasmids per strain. A significant increase in the mean number of plasmids per strain was seen during the observation period. Seventeen different plasmid sizes and 90 different plasmid profiles were identified. Plasmid profiling of S. berta appears to represent a promising tool for analysing the epidemiology of S. berta infections in broilers.

A pure culture of potentially pathogenic bacteria was obtained from 90% of 233 joints examined, originating from 232 ducks condemned due to arthritis at slaughter. S. typhi-murium and Staph. aureus were isolated from 61% and 18% of the joints respectively. E. coli was obtained from 6% of the cases, serogroup 078 being most prevalent. E. rhusiopathiae, Y. pseudo-tuberculosis, P. vulgaris, Micrococcus sp., Streptococcus sp., Acinetobacter sp., Flavobacterium sp., Pseudomonas sp. and Ae. formicans made up 12 cases. Serotypes other than S. typhi-murium were prevalent among ducks from all farms investigated, but S. typhi-murium was the only serotype demonstrated in arthritis. A high incidence of S. typhi-murium in the intestinal tract of ducks maintained on free range or in open houses suggests that these sites are sources of infection and that the intestinal tract is the portal of entry for S. typhi-murium causing arthritis. Ducks with arthritis at slaughter should always be totally condemned because of the public health hazard from the organisms most often associated with this condition.

The tracheal flora of healthy chickens consisted mainly of Gram-positive microorganisms. A shift to a predominantly Gram-negative flora, mainly due to Escherichia, was observed in chickens with respiratory symptoms caused by infectious bronchitis. Most of the chickens in which E. coli formed a predominant part of the tracheal flora also showed a positive serological reaction to Mycoplasma gallisepticum. A raised incidence of Pasteurella haemolytica with increase in age was noted both with regard to flocks and number of chickens examined. No differences other than those due to age were related to the incidence of P. haemolytica in trachea of chickens with and without respiratory symptoms. None of the isolated strains corresponds to earlier described biotypes of P. haemolytica. Intraperitoneal injection of P. haemolytica did not affect 1-day-old chickens, nor did simultaneous intratracheal injection of 14-day-old chickens with P. haemolytica and infectious bronchitis virus exacerbate subsequent infectious bronchitis. It can be presumed that P. haemolytica in certain environments constitutes a part of the normal tracheal flora in chickens beyond a certain age, and that invasion apparently only takes place in cases of extreme general debilitation.

During the period 1959 to 1968 0.4% of ducks slaughtered in Denmark were condemned because they had arthritis. The condemnation rate due to arthritis decreased 2 years after compulsory measures to control salmonella infections were introduced and in the 10 years from 1969 to 1978 this condemnation rate was 0.12%. The condemnation rate due to arthritis was relatively high during the period 1961 to 1967. A positive correlation between the condemnation rate due to arthritis and the number of ducks slaughtered and the overall condemnation rate existed at this time. Seasonal variations in the condemnation rate due to arthritis were observed. Mallards were found to be less susceptible to arthritis than White Pekin and Muscovy ducks reared under the same conditions. The hock was most frequently affected (43%) with arthritis. In 37% of arthritic birds the knee was affected, hip and toe joints being affected in 18% and 1% of cases respectively. Wing joints were affected in less than 1% of cases. The national annual cost of arthritis from 1959-1968 was estimated at 207, 579 Danish crowns. In the subsequent 10 years the cost was only one third of this sum.

Hereditary nonpolyposis colorectal cancer (HNPCC) is attributable to a deficiency of mismatch repair. Inactivation of DNA mismatch repair underlies the genesis of microsatellite instability in colorectal cancer. Germline mutations in three DNA mismatch repair genes, hMSH2, hMLH1, and hMSH6, have been found to segregate in HNPCC and HNPCC-like families. The two DNA mismatch repair genes hPMS1 and hPMS2 have also been suggested to predispose to HNPCC. In this study, 84 HNPCC and HNPCC-like kindreds without known mutations in the other three known DNA mismatch repair genes were screened for germline mutations in the hPMS1 or hPMS2 gene. No clear-cut pathogenic mutations were identified. Conversion technology was used to detect a large hMSH2 deletion in two affected members of the kindred in which the hPMS1 mutation was originally reported, whereas the hPMS1 mutation was only present in one of these two individuals. Since the hPMS1 and hPMS2 genes were first reported, germline mutations in hPMS2 have been demonstrated primarily in patients with Turcot's syndrome. However, no mutation in any of the two genes has been found to segregate in HNPCC families. Until there is better evidence for an increased colorectal cancer risk associated with germline mutations in these genes, a conservative interpretation of the role of mutations in these genes is advised.

The aim of the investigation was to compare four published PCR methods for specific detection of Pasteurella multocida. 85 strains of P. multocida and 13 strains of other taxa were included in the comparison of four published PCR methods based on kmt1, 23S rRNA and transcriptional regulator genes pm0762 and pm1231 as targets, respectively. Sensitivities were calculated to 100 and 80% for the kmt1 and 23S rRNA based PCRs, respectively and specificities to 92 and 23%, respectively of the kmt1 and 23S rRNA based PCRs. The methods based on transcriptional regulator genes tested two Bisgaard taxon 45 strains positive in addition to one Bisgaard taxon 16 strain. Only the kmt1 method detected P. multocida with the expected sensitivity and specificity and this method is recommended for identification of the species.

Plasmid profiles of 674 Salmonella berta strains isolated in the period 1985-1989 from 674 cases of human infections were recorded. Five hundred and eighty-nine of the strains examined (87.4%) contained plasmids and the mean number of plasmids was 1.8 per strain. Sixteen different plasmid sizes were recognized, 13 of which had also been reported from S. berta of poultry origin. The plasmids formed 90 different profiles. Forty-five of these profiles, comprising 90.7% of isolates, had previously been recorded among poultry strains. Only 12 human isolates (1.8%) carried plasmids which were not demonstrated among isolates obtained from broilers. The prevalences of the 20 most commonly demonstrated profiles were not significantly different among isolates obtained from humans and broilers. The average difference between the prevalences of individual plasmid profiles was 2.1, with a standard deviation of 4.2. Based on the results, indications are that broilers represent the main reservoir for human S. berta infections in Denmark.

To extend missions lifetime at very low altitudes, an efficient propulsion system is required to compensate for aerodynamic drag. One solution is Atmosphere-Breathing Electric Propulsion (ABEP). It collects atmospheric particles to be used as propellant for an electric thruster. The system ideally nullifies the requirement of onboard propellant storage. An ABEP system can be applied to any celestial body with atmosphere (Mars, Venus, Titan, etc.), enabling new mission at low altitude ranges for longer times. Challenging is operation of the thruster on reactive chemical species, such as atomic oxygen (AO), that is highly present in low Earth orbit, as they cause erosion of (not only) propulsion system components, i.e. acceleration grids, electrodes, neutralizers, and discharge channels of conventional EP systems. For this reason, a contactless plasma thruster is developed: the RF helicon-based plasma thruster (IPT). The paper describes the thruster design, implementation, and first ignition tests. The thruster presents a novel antenna called the birdcage antenna that is implemented for decades in magnetic resonance imaging (MRI) machines. The design is supported by the simulation tool XFdtd®. The IPT is aided by an externally applied static magnetic field that provides the boundary condition for the helicon wave formation within the plasma discharge. The antenna working principle allows to minimize losses in the electric circuit and provides, together with the applied magnetic field, acceleration of a quasi-neutral plasma plume.

The DISCOVERER project is developing technologies to enable commercially-viable sustained-operation of satellites in very low Earth orbits for communications and remote sensing applications. Operating closer to the surface of the Earth significantly reduces latency for communications applications and improves link budgets, whilst remote sensing also benefits from improved link budgets, the ability to have higher resolution or smaller instruments, all of which provide cost benefits. In addition, all applications benefit from increased launch mass to lower altitudes, whilst end-of-life removal is ensured due to the increased atmospheric drag. However, this drag must also be minimised and compensated for. DISCOVERER is developing several critical technologies to enable commercially viable operations in at these lower altitudes including aerodynamic materials, aerodynamic attitude and orbit control methods, atmosphere breathing electric propulsion and an in-situ environment monitoring payload. The current status of these developments are summarised, along with the plans for the coming year.

In very low Earth orbits (VLEO), below 450 km altitude, the aerodynamic properties of satellites are primarily determined by the flow regime, free molecular flow, and the interaction of atomic oxygen with the surfaces of the spacecraft. The Rarefied Orbital Aerodynamics Research (ROAR) facility is a novel experimental facility designed to simulate these conditions in a controlled environment to characterise the aerodynamic properties of materials. It is built as part of DISCOVERER, a Horizon 2020 project developing the different technologies required to enable the sustainable operation of satellites in VLEO. Because ROAR isn’t intended to perform erosion studies, it differs quite significantly from other atomic oxygen exposure experiments and its characteristics are discussed in this work. ROAR consists of an ultrahigh vacuum system, responsible for generating the free molecular flow conditions, a source of hyperthermal oxygen atoms at orbital velocities, and mass spectrometers; the latter used to characterise the gas-surface interactions, and therefore the material’s aerodynamic performance. This paper includes a description of ROAR’s main components, together with the experimental methodology for materials testing and early results. Among the main parameters to be considered are atomic oxygen flux, beam shape and energy spread, mass resolution, and signal-tonoise ratio.