Biofilm composition and function in stormwater constructed wetland systems on the Swan Coastal Plain, Western Australia

The ability of natural wetlands to act as effective nutrient sinks and to absorb new nutrient loadings is well documented. Constructed wetland systems (CWSs) aimed at optimising these nutrient removal mechanisms have been used for the removal of nutrients and pollutants from a variety of waters and wastewaters over the past thirty years. Over the past decade, the use of CWSs has extended to the removal of nutrients from urban stormwater, as a more ecologically sensible management option to the traditional method of discharging stormwater into natural wetlands. Stormwater CWSs on the Swan Coastal Plain are designed to remove phosphorus. Phosphorus is a commonly limiting nutrient affecting plant growth and the soils of the Coastal Plain have traditionally been heavily supplemented with phosphorus for urban and agricultural purposes. Despite the aims of these systems, stormwater CWSs on the Swan Coastal Plain have indicated poor phosphorus removal, typically 60-70% lower than their designed target. In contrast, natural wetlands on the Swan Coastal Plain have indicated significantly higher phosphorus removal. Conceptual models of phosphorus removal for CWSs suggest that phosphorus is predominantly removed by the biofilm component, suggested to account for more than half the cumulative phosphorus removal in the long-term. One hypothesis proposed to account for poor phosphorus removal in CWSs on the Swan Coastal Plain has been a lack of an active biofilm component. Biofilms cover every surface of aquatic systems in a thin film, and consist of an organic matrix of algae, fungi and bacteria embedded in polysaccharides. This study compared the biofilms of two CWSs with four physico-chemically distinct natural wetlands on the Swan Coastal Plain in order to justify or reject the proposed hypothesis. The study consisted of two distinctly separate experimental components. The first of these components aimed at quantifying the composition and biomass of biofilms, by investigating biofilm biomass in terms of organic, inorganic and percentage organic biomass, as well as biofilm composition in terms of the algal, fungal and bacterial component percentage cover. The second component aimed at determining the rate at which biofilm can remove phosphorus from the water column by a series of controlled nutrient depletion \u27batch-culture\u27 experiments. The results indicated that biofilms in natural wetlands on the Swan Coastal Plain were highly variable in terms of both biomass and composition. The two CWSs sampled indicated comparable biofilm biomass and composition, with the measured parameters generally falling within the ranges observed between the natural wetlands. The composition of biofilms appeared to be a reflection of the Photosynthetically active radiation (PAR) intensity at the sediment, with the biofilms in wetlands observed having high colour (low PAR intensity) being fungal/bacterial dominated, and biofilms in wetlands observed having low colour (high PAR intensity) being algal dominated. The biofilm composition of both CWSs was fungal/bacterial dominated because of high colour. The phosphorus removal rate by biofilm appeared to be concentration dependant, with negligible phosphorus removal at low concentrations. However, at high concentrations, the phosphorus removal rates established were significantly higher than those previously published, confirming that biofilms have the potential for significant phosphorus removal from CWSs. This research demonstrated that biofilms have the ability to remove significant quantities of phosphorus at reasonably high rates. Poor phosphorus removal of stormwater CWSs on the Swan Coastal Plain likely result from biofilm compositions poor at phosphorus removal, resulting from CWS design that fails to optimise both biofilm biomass and biofilm composition. The research results indicated that the engineering of algal-dominated biofilm composition by manipulating CWS design, as well as increasing the surface area for biofilm growth, may significantly increase phosphorus removal

Knowledge and the artefact

This paper discusses ways that knowledge may be found in or through artefacts. One purpose is to suggest situations where artefacts might be central to a narrative, rather than secondary to a text. A second purpose is to suggest ways that design and production of artefacts might be instrumental in eliciting knowledge. Four general situations are proposed: (1) Simple Forms - an artefact demonstrates or describes a principle or technique. (2) Communication of Process - artefacts arising from a process make the process explicit. (3) Artefacts Within the Research - artefacts are instrumental in advancing the research by communicating ideas or information. (4) Knowledge Elicited by Artefacts - artefacts provide a stimulus or context which enables information to be uncovered. .</p

Standard-M mobile satellite terminal employing electronic beam squint tracking

In recent years, extensive experience has been built up at the University of Bristol in the use of the Electronic Beam Squint (EBS) tracking technique, applied to large earth station facilities. The current interest in land mobile satellite terminals, using small tracking antennas, has prompted the investigation of the applicability of the EBS technique to this environment. The development of an L-band mechanically steered vehicle antenna is presented. A description of the antenna is followed by a detailed investigation of the tracking environment and its implications on the error detection capability of the system. Finally, the overall hardware configuration is described along with plans for future work

Discovery of distant high luminosity infrared galaxies

We have developed a method for selecting the most luminous galaxies detected by IRAS based on their extreme values of R, the ratio of 60 micron and B-band luminosity. These objects have optical counterparts that are close to or below the limits of Schmidt surveys. We have tested our method on a 1079 deg^2 region of sky, where we have selected a sample of IRAS sources with 60 micron flux densities greater than 0.2 Jy, corresponding to a redshift limit z~1 for objects with far-IR luminosities of 10^{13} L_sun. Optical identifications for these were obtained from the UK Schmidt Telescope plates, using the likelihood ratio method. Optical spectroscopy has been carried out to reliably identify and measure the redshifts of six objects with very faint optical counterparts, which are the only objects with R>100 in the sample. One object is a hyperluminous infrared galaxy (HyLIG) at z=0.834. Of the remaining, fainter objects, five are ultraluminous infrared galaxies (ULIGs) with a mean redshift of 0.45, higher than the highest known redshift of any non-hyperluminous ULIG prior to this study. High excitation lines reveal the presence of an active nucleus in the HyLIG, just as in the other known infrared-selected HyLIGs. In contrast, no high excitation lines are found in the non-hyperluminous ULIGs. We discuss the implications of our results for the number density of HyLIGs at z<1 and for the evolution of the infrared galaxy population out to this redshift, and show that substantial evolution is indicated. Our selection method is robust against the presence of gravitational lensing if the optical and infrared magnification factors are similar, and we suggest a way of using it to select candidate gravitationally lensed infrared galaxies.Comment: 6 pages, accepted for publication in A&

An Obstruction to Quantization of the Sphere

In the standard example of strict deformation quantization of the symplectic sphere $S^2$, the set of allowed values of the quantization parameter $\hbar$ is not connected; indeed, it is almost discrete. Li recently constructed a class of examples (including $S^2$) in which $\hbar$ can take any value in an interval, but these examples are badly behaved. Here, I identify a natural additional axiom for strict deformation quantization and prove that it implies that the parameter set for quantizing $S^2$ is never connected.Comment: 23 page. v2: changed sign conventio

Hypofractionation in Hepatocellular Carcinoma – The Effect of Fractionation Size

The use of stereotactic body radiotherapy (SBRT) in hepatocellular carcinoma (HCC) has increased over the years. Several prospective studies have demonstrated its safety and efficacy, and randomised trials are underway. The advancement in technology has enabled the transition from three-dimensional conformal radiotherapy to highly focused SBRT. Liver damage is the primary limiting toxicity with radiation, with the incidence of grade 3 varying from 0 to 30%. The reported radiotherapy fractionation schedule for HCC, and in practice use, ranges from one to 10 fractions, based on clinician preference and technology available, tumour location and tumour size. This review summarises the safety and efficacy of various SBRT fractionation schedules for HCC

Preliminary Canopy Removal Experiments in Algal Dominated Communities Low on the Shore and in the Shallow Subtidal on the Isle of Man

The algal dominated communities immediately above and below the low-water spring level on a moderately exposed Manx shore were investigated by canopy removal experiments. Fucus serratus, Laminaria digitata and L. hyperborea were removed. Competition was shown to be important in determining the zonation of L. digitata and the distribution along the wave exposure gradient of other species such as Alaria esculenta, Desmarestia aculeata and D. viridis, and L. saccharina. Many species of algal epiphytes were early colonizers of canopy removal areas suggesting that competition from canopy algae usually restricts them to an epiphytic habit. The results indicate that interactions between macrophytes are much more important than grazing in structuring these communities