3,916 research outputs found

    Improved methods for detecting gravitational waves associated with short gamma-ray bursts

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    In the era of second generation ground-based gravitational wave detectors, short gamma-ray bursts (GRBs) will be among the most promising astrophysical events for joint electromagnetic and gravitational wave observation. A targeted search for gravitational wave compact binary merger signals in coincidence with short GRBs was developed and used to analyze data from the first generation LIGO and Virgo instruments. In this paper, we present improvements to this search that enhance our ability to detect gravitational wave counterparts to short GRBs. Specifically, we introduce an improved method for estimating the gravitational wave background to obtain the event significance required to make detections; implement a method of tiling extended sky regions, as required when searching for signals associated to poorly localized GRBs from Fermi Gamma-ray Burst Monitor or the InterPlanetary Network; and incorporate astrophysical knowledge about the beaming of GRB emission to restrict the search parameter space. We describe the implementation of these enhancements and demonstrate how they improve the ability to observe binary merger gravitational wave signals associated with short GRBs.Comment: 13 pages, 6 figure

    The chaotic solar cycle II. Analysis of cosmogenic 10Be data

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    Context. The variations of solar activity over long time intervals using a solar activity reconstruction based on the cosmogenic radionuclide 10Be measured in polar ice cores are studied. Methods. By applying methods of nonlinear dynamics, the solar activity cycle is studied using solar activity proxies that have been reaching into the past for over 9300 years. The complexity of the system is expressed by several parameters of nonlinear dynamics, such as embedding dimension or false nearest neighbors, and the method of delay coordinates is applied to the time series. We also fit a damped random walk model, which accurately describes the variability of quasars, to the solar 10Be data and investigate the corresponding power spectral distribution. The periods in the data series were searched by the Fourier and wavelet analyses. The solar activity on the long-term scale is found to be on the edge of chaotic behavior. This can explain the observed intermittent period of longer lasting solar activity minima. Filtering the data by eliminating variations below a certain period (the periods of 380 yr and 57 yr were used) yields a far more regular behavior of solar activity. A comparison between the results for the 10Be data with the 14C data shows many similarities. Both cosmogenic isotopes are strongly correlated mutually and with solar activity. Finally, we find that a series of damped random walk models provides a good fit to the 10Be data with a fixed characteristic time scale of 1000 years, which is roughly consistent with the quasi-periods found by the Fourier and wavelet analyses.Comment: 8 pages, 11 figure

    European Non-native Species in Aquaculture Risk Analysis Scheme - a summary of assessment protocols and decision support tools for use of alien species in aquaculture

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    The European Non-native Species in Aquaculture Risk Analysis Scheme (ENSARS) was developed in response to European 'Council Regulation No. 708/2007 of 11 June 2007 concerning use of alien and locally absent species in aquaculture' to provide protocols for identifying and evaluating the potential risks of using non-native species in aquaculture. ENSARS is modular in structure and adapted from non-native species risk assessment schemes developed by the European and Mediterranean Plant Protection Organisation and for the UK. Seven of the eight ENSARS modules contain protocols for evaluating the risks of escape, introduction to and establishment in open waters, of any non-native aquatic organism being used (or associated with those used) in aquaculture, that is, transport pathways, rearing facilities, infectious agents, and the potential organism, ecosystem and socio-economic impacts. A concluding module is designed to summarise the risks and consider management options. During the assessments, each question requires the assessor to provide a response and confidence ranking for that response based on expert opinion. Each module can also be used individually, and each requires a specific form of expertise. Therefore, a multidisciplinary assessment team is recommended for its completion

    Stressed Skin Design of Steel Sheeting Panels – Part 1: Shear Resistance and Flexibility of Screw Lapped Joists

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    The shear resistance and flexibility of a steel roof diaphragm depend largely on shear resistance and slip flexibility of the single screw lap joint. In this paper, screw connections relevant to modern roof construction are investigated. The tests provided experimental values of shear/tearing resistance and joint flexibility of seam connections, cladding/purlin connections and purlin/rafter connections. The novel aspects of the experimental research include investigation of the behaviour of shear connections in 0.5mm thick sheeting and thick-to-thin connections in S550 high tensile steel. Overall, six series of tests were conducted and each test was repeated five times in order to demonstrate a scatter of test results. Test results were examined against existing semi-empirical formulas for predicting the shear resistance of screw joints. It was demonstrated that the design equation presented by Toma et al. (1993), without the additional condition included in Eurocode 3, offers the closest prediction in terms of joint shear resistance. In terms of joint flexibility, it was demonstrated that existing formulas developed for bolted connection (Zadanfarrokh and Bryan (1992) and Dubina and Zaharia (2006)) can be successfully used for screw connections. The flexibility reduction factor npf=0.4 was also proposed to take account of perfect fit screw connections

    Stressed Skin Design of Steel Sheeting Panels – Part 2: Shear Panels with Sheeting Fixed on all 4 Sides

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    In this paper, the strength and stiffness of different roof panels were investigated, in order to establish their ability to act as in-plane diaphragms for stressed skin design of cold-formed steel portal frames. A total of 6 roof panels, approximately 3 x 3m, were examined by testing with sheeting profiles fixed on 4 sides. A variety of sheeting profiles in two industry standard thicknesses of 0.5 and 0.7mm were tested, all using top-hat shaped purlins fixed with self-drilling, self-tapping screws. The experimental strength and stiffness of each panel were then compared against existing design methods. The Finite Element Analysis (FEA) modelling techniques were also presented and validated against series of full-scale tests. The FEA results have shown that the ‘true’ level of loading transferred via shear connector screws was on average 13% lower than that assumed by standard design methods. On the contrary, seam connections failure, according to FEA results, have governed a design in all of the analysed cases and the analytical method overestimated shear resistances of the panels by 45% and 35% in case of 0.5mm and 0.7mm thick sheeting profiles respectively. It was demonstrated that FEA results have represented the upper bound of experimental shear stiffness, with a very close prediction for 0.5mm thick sheeting profiles. Overall all, the tested panels demonstrated an average 41% greater flexibility then this predicted using FEA models

    Systematic review and meta-analysis of temozolomide in animal models of glioma:was clinical efficacy predicted?

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    Background:Malignant glioma is an aggressive tumour commonly associated with a dismal outcome despite optimal surgical and radio-chemotherapy. Since 2005 temozolomide has been established as first-line chemotherapy. We investigate the role of in vivo glioma models in predicting clinical efficacy.Methods:We searched three online databases to systematically identify publications testing temozolomide in animal models of glioma. Median survival and number of animals treated were extracted and quality was assessed using a 12-point scale; random effects meta-analysis was used to estimate efficacy. We analysed the impact of study design and quality and looked for evidence of publication bias.Results:We identified 60 publications using temozolomide in models of glioma, comprising 2443 animals. Temozolomide prolonged survival by a factor of 1.88 (95% CI 1.74-2.03) and reduced tumour volume by 50.4% (41.8-58.9) compared with untreated controls. Study design characteristics accounted for a significant proportion of between-study heterogeneity, and there was evidence of a significant publication bias.Conclusion:These data reflect those from clinical trials in that temozolomide improves survival and reduces tumour volume, even after accounting for publication bias. Experimental in vivo glioma studies of temozolomide differ from those of other glioma therapies in their consistent efficacy and successful translation into clinical medicine

    Time is not enough : promoting strategic engagement with writing for publication

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    Research, scholarship and publication are central to the work of higher education. However, even academics with the necessary research and writing skills can struggle to publish as often as they would like. Research suggests that a writing retreat is one solution; there is a process going on there that addresses the problem, but how it does so has not been fully explained. We used a novel approach, containment theory, to explain why the functions of a structured retreat work. We argue that a retreat does more than simply provide time to write; it is a model for academics to meet the demands of research assessment. Finally, we conceptualise this as strategic engagement - a model for producing regular writing for publication while continuing to meet other professional demands

    Hadronic interactions, precocious unification, and cosmic ray showers at Auger energies

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    At Auger energies only model predictions enable us to extract primary cosmic ray features. The simulation of the shower evolution depends sensitively on the first few interactions, necessarily related to the quality of our understanding of high energy hadronic collisions. Distortions of the standard ``soft semi-hard'' scenario include novel large compact dimensions and a string or quantum gravity scale not far above the electroweak scale. Na\"{\i}vely, the additional degrees of freedom yield unification of all forces in the TeV range. In this article we study the influence of such precocious unification during atmospheric cascade developments by analyzing the most relevant observables in proton induced showers.Comment: 16 pages latex. 4 eps figure

    Research opportunities for sustainable productivity improvement in the northern beef industry: A scoping study

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    The production and economic context of beef production in northern Australia has been seriously challenged over the last decade. Costs of production have escalated rapidly and beef prices have not increased in real terms since 2004 while productivity improvement, necessary to offset these cost-price pressures, has been slowing. Reversing these trends is imperative for a viable industry over the longer term. This report describes an approach taken to explore options for sustainable development of the industry as a basis for guiding research and development for the next two decades. A range of development scenarios that offer potential to significantly improve industry profitability through productivity gains were developed in consultation with industry and technical experts. The potential effect of these scenarios on productivity and economic and environmental outcomes of northern enterprises was evaluated using a new simulation model of northern beef enterprises. The evaluation was conducted for ten regions spanning Queensland, the Northern Territory and north-western Western Australia. The results suggest that significant gains in productivity and profitability can be achieved by integrating individual technologies that target specific components of the livestock system e.g. genetics, reproduction, nutrition
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