864 research outputs found

    Re-establishing recreational prawning in the Swan-Canning Estuary

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    This project builds on the work of a previous Recreational Fishing Initiatives Fund Project to pilot the culture and of the Western School Prawn (Metapenaeus dalli) in to the Swan-Canning Estuary and increase interest in prawning via a citizen science/community engagement project. Having developed, for the first time, successful aquaculture techniques for this species in the former project, the current project utilised these techniques to release ~2 million hatchery-reared post-larval M. dalli in to the Swan-Canning Estuary. It also produced good-quality data to inform the management of this iconic species, re-engaged community with the prawns and stewardship of the estuary through a citizen science program (Prawn Watch) and developed a refined citizen science monitoring program for M. dalli that could be used in the future

    Red Optical Planet Survey : A radial velocity search for low mass M dwarf planets

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedWe present radial velocity results from our Red Optical Planet Survey (ROPS), aimed at detecting low-mass planets orbiting mid-late M dwarfs. The similar to 10 ms(-1) precision achieved over 2 consecutive nights with the MIKE spectrograph at Magellan Clay is also found on week long timescales with UVES at VLT. Since we find that UVES is expected to attain photon limited precision of order 2 ms-1 using our novel deconvolution technique, we are limited only by the

    The Inverse Amplitude Method and Heavy Baryon Chiral Perturbation Theory applied to pion-nucleon scattering

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    We report on our present work, where by means of the Inverse Amplitude Method we unitarize the elastic pion nucleon scattering amplitudes of Heavy Barion Chiral Perturbation Theory at O(q^3). We reproduce the scattering up to the inelastic thresholds including the Delta(1232) resonance. The fitted chiral constants are rather different from those obtained by fitting the extrapolated threshold parameters for the non-unitarized theory.Comment: Talk given at the 8th International Conference on Hadron Spectroscopy, HADRON99, August 24-28, 1999, Beijing, China. 4 pages LaTex, uses espcrc1.sty (included

    Intermittent structural weakening and acceleration of the Thwaites Glacier Tongue between 2000 and 2018

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    Evolving conditions at the terminus of Thwaites Glacier will be important in determining the rate of its future sea-level contribution over the coming decades. Here, we use remote-sensing observations to investigate recent changes (2000–2018) in the structure and velocity of Thwaites Glacier and its floating tongue. We show that the main trunk of Thwaites Glacier has accelerated by 38% over this period, while its previously intact floating tongue has transitioned to a weaker mélange of fractured icebergs bounded by sea ice. However, the rate of structural weakening and acceleration was not uniform across the observational period and we identify two periods of rapid acceleration and structural weakening (2006–2012; 2016–2018), separated by a period of deceleration and re-advance of the structurally-intact shear margin boundary (2012–2015). The timing of these accelerations/decelerations strongly suggests a link to variable ocean forcing. The weakened tongue now has some dependency on landfast sea ice for structural integrity and is vulnerable to changes in landfast ice persistency. Future reductions in landfast sea ice could manifest from changes in climate and/or the imminent removal of the B-22A iceberg from the Thwaites embayment. Such changes could have important implications for the integrity of the ice tongue and future glacier discharge

    The Predictive Validity of the Early Warning System Tool

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    The Early Warning System (EWS) is a tool developed by the National High School Center to collect data on indicators including attendance, GPA, course failures and credits earned. These indicators have been found to be highly predictive of a student’s likelihood of dropping out of high school in large, urban areas. The EWS tool was studied in two suburban schools. With the exception of attendance data, findings suggest that the indicators and suggested threshold for risk determination are predictive in suburban contexts

    SALT observations of the Chromospheric Activity of Transiting Planet Hosts: Mass Loss and Star Planet Interactions

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    We measured the chromospheric activity of the four hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 to search for anomalous values caused by the close-in companions. The Mount Wilson Ca II H&K S-index was calculated for each star using observations taken with the Robert Stobie Spectrograph at the Southern African Large Telescope. The activity level of WASP-43 is anomalously high relative to its age and falls among the highest values of all known main sequence stars. We found marginal evidence that the activity of WASP-103 is also higher than expected from the system age. We suggest that for WASP-43 and WASP-103 star-planet interactions (SPI) may enhance the Ca II H&K core emission. The activity levels of WASP-51/HAT-P-30 and WASP-72 are anomalously low, with the latter falling below the basal envelope for both main sequence and evolved stars. This can be attributed to circumstellar absorption due to planetary mass loss, though absorption in the ISM may contribute. A quarter of known short period planet hosts exhibit anomalously low activity levels, including systems with hot Jupiters and low mass companions. Since SPI can elevate and absorption can suppress the observed chromospheric activity of stars with close-in planets, their Ca II H&K activity levels are an unreliable age indicator. Systems where the activity is depressed by absorption from planetary mass loss are key targets for examining planet compositions through transmission spectroscopy

    VIP enhances TRH-stimulated prolactin secretion of pituitary tumours Studies with 31P NMR

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    AbstractIntravenous thyrotrophin releasing hormone (TRH) caused a 6.5-fold increase in plasma prolactin (PRL) in rats carrying implanted pituitary tumours. Vasoactive intestinal polypeptide (VIP) had no effect, but TRH given after VIP raised TRH stimulated secretion 13-fold above basal. 31P NMR spectroscopy showed that VIP caused a decrease in high energy metabolites (depleted phosphocreatine, elevated inorganic phosphate and lowered intracellular pH). TRH alone caused a similar but smaller effect; given after VIP, it caused no detectable depletion. We suggest that the changes in high energy metabolite cencentrations reflect increased cellular energy consumption consistent with a priming process (stage 1) in PRL secretion, followed by hormone release (stage 2). VIP induces stage 1 whereas RTH induced both stages

    Restocking of the Western School Prawn (Metapenaeus dalli) in the Swan Canning Riverpark

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    This report provides the first comprehensive investigation into the biology and ecology of the Western School Prawn (Metapenaeus dalli) in the Swan-Canning Estuary in south-western Australia. It provides knowledge to help manage the fishery and evaluate release strategies for the aquaculture-based enhancement of this species. The study involved Murdoch University, the Department of Biodiversity, Conservation and Attractions (DBCA) (formerly Department of Parks and Wildlife and the Swan River Trust) and the Australian Centre for Applied Aquaculture Research (ACAAR). It was designed to complement a concurrent project to develop aquaculture techniques to produce and release M. dalli and re-engage the local community with prawning and the estuary (led by ACAAR, DBCA’s Parks and Wildlife Service and the West Australian Fish Foundation), funded by the Recreational Fishing Initiatives Fund. The Fisheries Research and Development Corporation provided matching funds for the current study. Biological data on M. dalli were collected from 20 sites in nearshore and 16 in the offshore waters of the Swan-Canning Estuary, ranging from the mouth of the system to ~40 and 30 km upstream in the Swan and Canning rivers, respectively, in every lunar month between October 2013 and March 2016. Laboratory studies were also completed to investigate the survival and growth of larval prawns in different salinity, water temperature and algal food conditions. Results were presented as part of the Prawn Watch program to engage the community in the research and encourage stewardship of the fishery and the estuary

    Contributions from SUSY-FCNC couplings to the interpretation of the HyperCP events for the decay \Sigma^+ \to p \mu^+ \mu^-

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    The observation of three events for the decay Σ+→pμ+μ−\Sigma^+ \to p \mu^+ \mu^- with a dimuon invariant mass of 214.3±0.5214.3\pm0.5MeV by the HyperCP collaboration imply that a new particle X may be needed to explain the observed dimuon invariant mass distribution. We show that there are regions in the SUSY-FCNC parameter space where the A10A^0_1 in the NMSSM can be used to explain the HyperCP events without contradicting all the existing constraints from the measurements of the kaon decays, and the constraints from the K0−Kˉ0K^0-\bar{K}^0 mixing are automatically satisfied once the constraints from kaon decays are satisfied.Comment: 18 pages, 7 figure
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