ALBERT

Notes: The Z-pinch-driven hohlraum (ZPDH) [J. H. Hammer et al., Phys. Plasmas 6, 2129 (1999)] is a promising approach to high yield inertial confinement fusion currently being characterized in experiments on the Sandia Z accelerator [M. E. Cuneo et al., Phys. Plasmas 8, 2257 (2001)]. Simulations show that capsule radiation symmetry, a critical issue in ZPDH design, is governed primarily by hohlraum geometry, dual-pinch power balance, and pinch timing. In initial symmetry studies on Z without the benefit of a laser backlighter, highly-asymmetric pole-hot and equator-hot single Z-pinch hohlraum geometries were diagnosed using solid low density foam burnthrough spheres. These experiments demonstrated effective geometric control and prediction of polar flux symmetry at the level where details of the Z-pinch implosion and other higher order effects are not critical. Radiation flux symmetry achieved in Z double-pinch hohlraum configurations exceeds the measurement sensitivity of this self-backlit foam ball symmetry diagnostic. To diagnose radiation symmetry at the 2%–5% level attainable with present ZPDH designs, high-energy x rays produced by the recently-completed Z-Beamlet laser backlighter are being used for point-projection imaging of thin-wall implosion and symmetry capsules. © 2002 American Institute of Physics.

Notes: The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L.), particularly in the southern Great Plains of the USA. Winter barley targeted for production in this region should incorporate resistance to greenbug in the form of the resistance gene Rsg1a (in ‘Post 90′) or Rsg2b (in PI 426756). This study was conducted to fully characterize the resistance profile of these two genes against important greenbug biotypes, and to determine which of the two resistance genes is most effective in protecting barley from the greenbug. Eight barley and four wheat cultivars and germplasms were challenged with six greenbug biotypes and damage ratings were recorded for each combination. In five of the six tests, ‘Post 90’ was significantly more resistant than PI 426756 to greenbug feeding damage. Based on the results presented here, we conclude that the resistance gene, Rsg1a, in ‘Post 90’ is the better choice for use in breeding programmes and will provide better protection than Rsg2b against the greenbug.

Notes: There is increasing public, governmental and commercial interest in the welfare of intensively farmed fish and stocking density has been highlighted as an area of particular concern. Here we draw scientific attention and debate to this emerging research field by reviewing the evidence for effects of density on rainbow trout. Although no explicit reference to ‘welfare’ has been made, there are 43 studies which have examined the effects of density on production and physiological parameters of rainbow trout. Increasing stocking density does not appear to cause prolonged crowding stress in rainbow trout. However, commonly reported effects of increasing density are reductions in food conversion efficiency, nutritional condition and growth, and an increase in fin erosion. Such changes are indicative of a reduced welfare status—although the magnitude of the effects has tended to be dependent upon study-specific conditions. Systematic observations on large scale commercial farms are therefore required, rather than extrapolation of these mainly small-scale experimental findings. There is dispute as to the cause of the observed effects of increasing density, with water quality deterioration and/or an increase in aggressive behaviour being variously proposed. Both causes can theoretically generate the observed effects of increasing density, and the relative contribution of the two causes may depend upon the specific conditions. However, documentation of the relationship between density and the effects of aggressive behaviour at relevant commercial densities is lacking. Consequently only inferential evidence exists that aggressive behaviour generates the observed effects of increasing density, whereas there is direct experimental evidence that water quality degradation is responsible. Nevertheless, there are contradictory recommendations in the literature for key water quality parameters to ensure adequate welfare status. The potential for welfare to be detrimentally affected by non-aggressive behavioural interactions (abrasion, collision, obstruction) and low densities (due to excessive aggressive behaviour and a poor feeding response) have been largely overlooked. Legislation directly limiting stocking density is likely to be unworkable, and a more practical option might be to prescribe acceptable levels of water quality, health, nutritional condition and behavioural indicators.

Notes: Antibody phage display libraries (Griffin and Tomlinson I) displaying antibody genes and maintained and amplified in Escherichia coli were used to isolate antibodies to the hapten target microcystin LR (1000 Da) conjugated to either bovine serum albumin or keyhole limpet haemocyanin. In competition enzyme-linked immunosorbent assay, bacterially expressed antibodies selected via the Griffin library showed at least 300 times greater sensitivity than those isolated from the Tomlinson library, for free microcystin. Bacterially expressed phage antibody libraries provide a rapid and relatively easy route for the selection of monoclonal antibodies specific for even the most difficult of antigenic targets such as free haptens.

Notes: : Water quality issues in agriculture are growing in importance. A common theme is the provision of better information to decision makers. This study reports the trial of a prototype decision support system by the U.S. Department of Agriculture Natural Resources Conservation Service and the Agricultural Research Service in the NRCS Harrison County Field Office in 1998. Observed data collected at the Deep Loess Research Station (DLRS) near Treynor, Iowa, were extrapolated using a modified GLEAMS field scale simulation model that included a nitrogen leaching component and a crop growth component. An accounting tool was used to convert crop yield estimates into crop budgets. A model interface was built to specify the climate, soil, and topography of the field, as well as the management scenarios for the alternative management systems. For the Deep Loess Hills area of Harrison County, a total of six soil and slope groups, with 66 total combinations of management practices forming management systems, were defined and simulated based on previously calibrated data from DLRS. A multi-objective decision support system, the Water Quality Decision Support System, or WQDSS, was used to examine the tradeoffs in a comprehensive set of variables affected by alternative management systems with farmers in Harrison County. The study concluded that a multiobjective decision support system should be developed to support conservation planning by the NRCS. Currently, a larger scale effort to improve water quality decision making is underway.

Notes: Filamentous microbial mats from three aphotic sulfidic springs in Lower Kane Cave, Wyoming, were assessed with regard to bacterial diversity, community structure, and ecosystem function using a 16S rDNA-based phylogenetic approach combined with elemental content and stable carbon isotope ratio analyses. The most prevalent mat morphotype consisted of white filament bundles, with low C:N ratios (3.5–5.4) and high sulfur content (16.1–51.2%). White filament bundles and two other mat morphotypes had organic carbon isotope values (mean δ13C =−34.7‰, 1σ= 3.6) consistent with chemolithoautotrophic carbon fixation from a dissolved inorganic carbon reservoir (cave water, mean δ13C =−7.4‰ for two springs, n= 8). Bacterial diversity was low overall in the clone libraries, and the most abundant taxonomic group was affiliated with the “Epsilonproteobacteria” (68%), with other bacterial sequences affiliated with Gammaproteobacteria (12.2%), Betaproteobacteria (11.7%), Deltaproteobacteria (0.8%), and the Acidobacterium (5.6%) and Bacteriodetes/Chlorobi (1.7%) divisions. Six distinct epsilonproteobacterial taxonomic groups were identified from the microbial mats. Epsilonproteobacterial and bacterial group abundances and community structure shifted from the spring orifices downstream, corresponding to changes in dissolved sulfide and oxygen concentrations and metabolic requirements of certain bacterial groups. Most of the clone sequences for epsilonproteobacterial groups were retrieved from areas with high sulfide and low oxygen concentrations, whereas Thiothrix spp. and Thiobacillus spp. had higher retrieved clone abundances where conditions of low sulfide and high oxygen concentrations were measured. Genetic and metabolic diversity among the “Epsilonproteobacteria” maximizes overall cave ecosystem function, and these organisms play a significant role in providing chemolithoautotrophic energy to the otherwise nutrient-poor cave habitat. Our results demonstrate that sulfur cycling supports subsurface ecosystems through chemolithoautotrophy and expand the evolutionary and ecological views of “Epsilonproteobacteria” in terrestrial habitats.