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The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
The class of radio transients called Fast Radio Bursts (FRBs) encompasses enigmatic single pulses, each unique in its own way, hindering a consensus for their origin. The key to demystifying FRBs lies in discovering many of them in order to identity commonalities – and in real time, in order to find potential counterparts at other wavelengths. The recently upgraded UTMOST in Australia, is undergoing a backend transformation to rise as a fast transient detection machine. The first interferometric detections of FRBs with UTMOST, place their origin beyond the near-field region of the telescope thus ruling out local sources of interference as a possible origin. We have localised these bursts to much better than the ones discovered at the Parkes radio telescope and have plans to upgrade UTMOST to be capable of much better localisation still.
We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array’s performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.
Almost half of all known microsporidian taxa infect aquatic animals. Of these, many cause disease in arthropods. Hepatospora, a recently erected genus, infects epithelial cells of the hepatopancreas of wild and farmed decapod crustaceans. We isolated Hepatospora spp. from three different crustacean hosts, inhabiting different habitats and niches; marine edible crab (Cancer pagurus), estuarine and freshwater Chinese mitten crab (Eriocheir sinensis) and the marine mussel symbiont pea crab (Pinnotheres pisum). Isolates were initially compared using histology and electron microscopy revealing variation in size, polar filament arrangement and nuclear development. However, sequence analysis of the partial SSU rDNA gene could not distinguish between the isolates (~99% similarity). In an attempt to resolve the relationship between Hepatospora isolated from E. sinensis and C. pagurus, six additional gene sequences were mined from on-going unpublished genome projects (RNA polymerase, arginyl tRNA synthetase, prolyl tRNA synthetase, chitin synthase, beta tubulin and heat shock protein 70). Primers were designed based on the above gene sequences to analyse Hepatospora isolated from pea crab. Despite application of gene sequences to concatenated phylogenies, we were unable to discriminate Hepatospora isolates obtained from these hosts and concluded that they likely represent a single species or, at least subspecies thereof. In this instance, concatenated phylogenetic analysis supported the SSU-based phylogeny, and further, demonstrated that microsporidian taxonomies based upon morphology alone are unreliable, even at the level of the species. Our data, together with description of H. eriocheir in Asian crab farms, reveal a preponderance for microvariants of this parasite to infect the gut of a wide array of decapods crustacean hosts and the potential for Hepatospora to exist as a cline across wide geographies and habitats.
In late 2011 the New Zealand Ministry for Primary Industries reported an increase in confirmed laboratory diagnoses of salmonellosis in dairy herds. To identify risk factors for herd-level outbreaks of salmonellosis we conducted a case-control study of New Zealand dairy herds in 2011–2012. In a multivariable analysis, use of continuous feed troughs [adjusted odds ratio (aOR) 6·2, 95% confidence interval (CI) 2·0–20], use of pelletized magnesium supplements (aOR 10, 95% CI 3·3–33) and use of palm kernel meal as a supplementary feed (aOR 8·7, 95% CI 2·5–30) were positively associated with a herd-level outbreak of salmonellosis between 1 July 2011 and 31 January 2012. We conclude that supplementary feeds used on dairy farms (regardless of type) need to be stored and handled appropriately to reduce the likelihood of bacterial contamination, particularly from birds and rodents. Magnesium supplementation in the pelletized form played a role in triggering outbreaks of acute salmonellosis in New Zealand dairy herds in 2011–2012.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
The significance of the potential impacts of microbial activity on the transport properties of host rocks for geological repositories is an area of active research. Most recent work has focused on granitic environments. This paper describes pilot studies investigating changes in transport properties that are produced by microbial activity in sedimentary rock environments in northern Japan. For the first time, these short experiments (39 days maximum) have shown that the denitrifying bacteria, Pseudomonas denitrificans, can survive and thrive when injected into flow-through column experiments containing fractured diatomaceous mudstone and synthetic groundwater under pressurized conditions. Although there were few significant changes in the fluid chemistry, changes in the permeability of the biotic column, which can be explained by the observed biofilm formation, were quantitatively monitored. These same methodologies could also be adapted to obtain information from cores originating from a variety of geological environments including oil reservoirs, aquifers and toxic waste disposal sites to provide an understanding of the impact of microbial activity on the transport of a range of solutes, such as groundwater contaminants and gases (e.g. injected carbon dioxide).
Microbial activity can have a significant impact on geochemical processes as it can influence mineral dissolution and precipitation, pH, alkalinity and redox. Experiments were conducted to study the rock-water and microbial interactions, specifically to examine the influence of microbes on the groundwater environment in fractured crystalline rock. These used combinations of crushed Äspö Diorite, Äspö groundwater with iron and sulphate reducing bacteria in columns and continuously stirred tank reactors under both anaerobic and aerobic conditions. Results showed loss (dissolution and/or mobilization) of fine grained crushed material (<50 μm) which had originally adhered to grain surfaces in the starting material. The mobilized fines were subsequently trapped on biofilms developed between grains. There was also evidence for the formation of smectite (not present in the starting materials) which, together with the trapping of translocated fines in intergranular pore throats by biofilms, resulted in blockage of the column experiments. The degree of mineralogical alteration and/or pore blocking was greater in the experiments when bacteria were present and occurred under anaerobic conditions. Little evidence for rock-water interactions was seen in the chemical analysis data for all the experiments. Modelling of the fluids showed them to be saturated with respect to clay minerals. The observed mineralogical changes seem to reflect alteration occurring in microbially mediated microenvironments close to mineral surfaces. Consequently, these changes may be too small to be detected by the chemical analysis of the bulk fluid. These experiments have shown that microbial activity can impact on fluid flow through porous media even in nutrient poor conditions. In addition, the formation of new clay minerals on pore-surfaces is potentially important for ion exchange and sorption reactions.
In order to be able to describe the migration of an alkaline plume, coupled chemistry and flow computer models may be employed. A series of laboratory column experiments were conducted to test the capabilities of currently available coupled models to predict product solids and output fluid compositions as a function of time. The predictions did not replicate all the variations of Ca:Si observed during mineralogical analysis, probably due the unavailability of sufficient kinetic and thermodynamic data for the range of calcium silicate hydrates (CSH) phases of interest. However, the predictions do reproduce the variation of Ca:Si ratios with time and distance along the columns. A better understanding of the above processes will lead to greater confidence in predictive modelling of the migration of alkaline plumes away from the cementitious barriers of radioactive waste disposal facilities.
Argonne National Laboratory has developed a composite ceramic waste form for the disposition of high level radioactive waste produced during electrometallurgical conditioning of spent nuclear fuel. The electrorefiner LiCl/KCl eutectic salt, containing fission products and transuranics in the chloride form, is contacted with a zeolite material which removes the fission products from the salt. After salt contact, the zeolite is mixed with a glass binder. The zeolite/glass mixture is then hot isostatic pressed (HIPed) to produce the composite ceramic waste form. The ceramic waste form provides a durable medium that is well suited to incorporate fission products and transuranics in the chloride form. Presented are preliminary results of the process qualification and characterization studies, which include chemical and physical measurements and product durability testing, of the ceramic waste form.
The laboratory experiments described here, were aimed at examining the interaction of microbes with mineralogical surfaces involved with groundwater flow. These experiments were designed to study simple systems and were aimed at identifying relevant reactions both chemical and biological. They contained groundwater with either sulphate reducing bacteria (SRB), iron reducing bacteria (IRB) or a mixture of both, together with control experiments without bacteria. The results of the chemical analyses of fluid phases showed evidence for dissolution of primary minerals. Microbial analysis showed both SRB and IRB appeared to be active albeit for a limited period due to exhaustion of nutrient and energy supplies. SRB seem to have a greater effect on groundwater chemistry than IRB with sulphide being produced. However, when the two types of bacteria are mixed together, the IRB appear to dominate the system. Further work is underway to give detailed mineralogical analysis of the solids in order to better understand the influence of microbial interaction on the redox reactions.
Experiments were conducted to identify the rock-water and microbial interactions influencing accelerated smectite-clay formation. Packed columns and stirred batch reactors contained Äspö granodiorite, artificial groundwater mimicking that from Äspö and combinations of three types of subsurface chemolithotrophic bacteria, two of which were indigenous to the Äspö rocks. Results showed evidence that, within 5 days under anaerobic reducing conditions, all three of the bacterial types produced copious biofilamentous ‘meshes’ across porespaces, apparently using the larger grains as anchor points. The biofilaments quickly became encrusted with fine grained material and surrounded with neoformed clay-like deposits. In contrast, the abiotic controls showed little or no evidence of clay formation suggesting that this process is biologically induced or controlled. A second series of abiotic experiments to determine the effects of increased acidity showed evidence of mineral pitting and dissolution along with an increase in concentration of soluble species thought to be important in smectite formation (i.e. Si, Al, Mg, Fe, Ca, Na). However, there was no evidence of clay formation, and the biotic experiments showed no signs of bulk scale pH change, suggesting that either the bacteria are actively concentrating relevant chemical species at a local level or they are acting as templates or nucleation points for clay formation.
This study examined patterns in the species richness and abundance of small non-volant mammals along a tropical altitudinal gradient in north-eastern Australia. We investigated whether a mid-altitudinal peak in diversity was apparent, and if it occurred, whether it was determined by particular environmental conditions. We sampled a small-mammal assemblage at 17 sites distributed along an altitude-environmental gradient from savanna (350 m) to rain-forest vegetation (1000 m). Over four separate occasions (5100 trap-nights) we recorded 17 species of mammal with 416 captures. A positive non-linear relationship between altitude and mammal species richness and abundance was observed, peaking at the 800–900 m range. Many species were distributed across a range of altitudes, while others were strongly associated with particular habitat conditions. There was a distinct reduction in abundance and species richness at low altitudes associated with the less complex vegetation, lower productivity and possible anthropogenic effects. Key findings were: that small-mammal richness peaked towards the summit of the gradient and not at one-half the maximum altitude predicted by the mid-domain effect; contrasting conditions and greatest vegetation juxtaposition had the greatest influence on the patterns recorded; and that local idiosyncratic influences such as habitat factors, land management and historical biogeography are significant.
Information and communication technologies, especially in the forms of mobile telecommunications, satellite imaging, and geographical information systems, promise to significantly improve the practice of humanitarian relief. A working group convened at the Humanitarian Action Summit 2009, has begun investigating the challenges to implementing these technologies in field operations, keeping in mind the ethical considerations of linking people to place, and pledging to build a community of practice among academics, practitioners, and developers.
Landfill and radioactive waste disposal risk assessments focus on contaminant transport and are principally concerned with understanding the movement of gas, water and solutes through engineered barriers and naturalgroundwater systems. However, microbiologicalactivity can impact on transport processes changing the chemicaland physicalcharacteristics of the subsurface environment. Such effects are generally caused by biofilms attached to rock surfaces. This paper will present some mineralogical and petrographical observations of materials extracted at the completion of an experimental column study which examined the influences of biofilm growth on groundwater flow through crushed diorite from the Äspö Hard Rock Underground Research Laboratory, Sweden.
Abnormalities of the first branchial cleft are rare. They may present with a cutaneous defect in the neck, parotid region, external auditory meatus or peri-auricular area, or with inflammatory or infective lesions at these sites.
A retrospective case note review of the patients treated by the senior author is presented. This group consisted of 18 patients and represents the largest published UK series to date. Eleven patients (65 per cent) had undergone incomplete surgery prior to referral.
Over half the patients had a clinically apparent lesion in relation to the external auditory meatus. There was a variable relationship between the tract and the facial nerve, which was identified at surgery in 15 cases.
These findings are consistent with those of previously published series. Clinicians should keep this diagnosis in mind when assessing patients with infected lesions in the neck and parotid area. Surgeons should be familiar with parotid surgery, in children where appropriate, and be prepared to expose the facial nerve before embarking on the surgical management of these lesions.