6,298 research outputs found

    Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch

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    A method combining photogrammetry with ballistic analysis is demonstrated to identify flying debris in a rocket launch environment. Debris traveling near the STS-124 Space Shuttle was captured on cameras viewing the launch pad within the first few seconds after launch. One particular piece of debris caught the attention of investigators studying the release of flame trench fire bricks because its high trajectory could indicate a flight risk to the Space Shuttle. Digitized images from two pad perimeter high-speed 16-mm film cameras were processed using photogrammetry software based on a multi-parameter optimization technique. Reference points in the image were found from 3D CAD models of the launch pad and from surveyed points on the pad. The three-dimensional reference points were matched to the equivalent two-dimensional camera projections by optimizing the camera model parameters using a gradient search optimization technique. Using this method of solving the triangulation problem, the xyz position of the object's path relative to the reference point coordinate system was found for every set of synchronized images. This trajectory was then compared to a predicted trajectory while performing regression analysis on the ballistic coefficient and other parameters. This identified, with a high degree of confidence, the object's material density and thus its probable origin within the launch pad environment. Future extensions of this methodology may make it possible to diagnose the underlying causes of debris-releasing events in near-real time, thus improving flight safety.Comment: 26 pages, 11 figures, 3 table

    Repair of juxtarenal para-anastomotic aortic aneurysms after previous open repair with fenestrated and branched endovascular stent grafts

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    Three patients with juxtarenal para-anastomotic aortic aneurysms after previous open abdominal aortic aneurysm repair were treated with custom-designed fenestrated and branched Zenith endovascular stent grafts. Six renal arteries and two superior mesenteric arteries were targeted for incorporation by graft fenestrations and branches. The fenestration/renal ostium interface was secured with balloon-expandable Genesis stents (n = 5) or Jostent stent grafts (n = 1). Completion angiography demonstrated no endoleaks and antegrade perfusion in all target vessels. During follow-up, one patient developed asymptomatic renal artery occlusion and underwent further endovascular intervention for type I distal endoleak. Computed tomography at 12 months demonstrated complete aneurysm exclusion in all patients with antegrade perfusion in the remaining target vessels. Fenestrated and branched endovascular stent grafts may be an acceptable alternative to conventional open repair in this group of patients

    Low fuel cost and rising fish price threaten coral reef wilderness

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    Wilderness areas offer unparalleled ecosystem conditions. However, growing human populations and consumption are among factors that drive encroachment on these areas. Here, we explore the threat of small‐scale fisheries to wilderness reefs by developing a framework and modeling fluctuations in fishery range with fuel costs and fish prices. We modeled biomass of four fishery groups across the New Caledonian archipelago, and used fish and fuel prices from 2005 to 2020 to estimate the extent of exploited reefs across three fishing scenarios. From 2012 to 2018, maximum profitable range increased from 15 to over 30 hr from the capital city, expanding to reefs previously uneconomic to fish, including a UNESCO heritage site. By 2020, over half of New Caledonian (∼17% global) wilderness reefs will become profitable to fish. Our results demonstrate that remoteness from humans should not be considered protection for wilderness coral reefs in the context of rising fish prices

    Belimumab : a technological advance for systemic lupus erythematosus patients? Report of a systematic review and meta-analysis

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    Objectives: To undertake a systematic review and meta-analysis to investigate clinical effectiveness of belimumab for patients with systemic lupus erythematosus (SLE) and antinuclear and/or anti-double-stranded DNA (dsDNA) autoantibodies. Methods: We searched eight electronic databases and reference lists for randomised controlled trials (RCTs) of belimumab against placebo or best supportive care. Quality assessment and random effects meta-analysis were undertaken. Design: A meta-analysis of RCTs. Participants: 2133 SLE patients. Primary and secondary outcome measures: SLE Responder Index (SRI) at week 52. Results: Three double-blind placebo-controlled RCTs (L02, BLISS-52 BLISS-76) investigated 2133 SLE patients. BLISS-52 and BLISS-76 trials recruited patients with antinuclear and/or anti-dsDNA autoantibodies and demonstrated belimumab effectiveness for the SRI at week 52. Ethnicity and geographical location of participants varied considerably between BLISS trials. Although tests for statistical heterogeneity were negative, BLISS-52 results were systematically more favourable for all measured outcomes. Meta-analysis of pooled 52-week SRI BLISS results showed benefit for belimumab (OR 1.63, 95% CI 1.27 to 2.09). By week 76, the primary SRI outcome in BLISS-76 was not statistically significant (OR 1.31, 95% CI 0.919 to 1.855)

    Characterisation of Campylobacter jejuni genes potentially involved in phosphonate degradation

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    Potential biological roles of the Campylobacter jejuni genes cj0641, cj0774c and cj1663 were investigated. The proteins encoded by these genes showed sequence similarities to the phosphonate utilisation PhnH, K and L gene products of Escherichia coli. The genes cj0641, cj0774c and cj1663 were amplified from the pathogenic C. jejuni strain 81116, sequenced, and cloned into pGEM-T Easy vectors. Recombinant plasmids were used to disrupt each one of the genes by inserting a kanamycin resistance (KmR) cassette employing site-directed mutagenesis or inverse PCR. Campylobacter jejuni 81116 isogenic mutants were generated by integration of the mutated genes into the genome of the wild-type strain. The C. jejuni mutants grew on primary isolation plates, but they could not be purified by subsequent passages owing to cell death. The mutant C. jejuni strains survived and proliferated in co-cultures with wild-type bacteria or in media in which wild-type C. jejuni had been previously grown. PCR analyses of mixed wild-type/mutant cultures served to verify the presence of the mutated gene in the genome of a fraction of the total bacterial population. The data suggested that each mutation inactivated a gene essential for survival. Rates of phosphonate catabolism in lysates of E. coli strain DH5α were determined using proton nuclear magnetic resonance spectroscopy. Whole-cell lysates of the wild-type degraded phosphonoacetate, phenylphosphonate and aminomethylphosphonate. Significant differences in the rates of phosphonate degradation were observed between lysates of wild-type E. coli, and of bacteria transformed with each one of the vectors carrying one of the C. jejuni genes, suggesting that these genes were involved in phosphonate catabolism

    Autocalibration with the Minimum Number of Cameras with Known Pixel Shape

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    In 3D reconstruction, the recovery of the calibration parameters of the cameras is paramount since it provides metric information about the observed scene, e.g., measures of angles and ratios of distances. Autocalibration enables the estimation of the camera parameters without using a calibration device, but by enforcing simple constraints on the camera parameters. In the absence of information about the internal camera parameters such as the focal length and the principal point, the knowledge of the camera pixel shape is usually the only available constraint. Given a projective reconstruction of a rigid scene, we address the problem of the autocalibration of a minimal set of cameras with known pixel shape and otherwise arbitrarily varying intrinsic and extrinsic parameters. We propose an algorithm that only requires 5 cameras (the theoretical minimum), thus halving the number of cameras required by previous algorithms based on the same constraint. To this purpose, we introduce as our basic geometric tool the six-line conic variety (SLCV), consisting in the set of planes intersecting six given lines of 3D space in points of a conic. We show that the set of solutions of the Euclidean upgrading problem for three cameras with known pixel shape can be parameterized in a computationally efficient way. This parameterization is then used to solve autocalibration from five or more cameras, reducing the three-dimensional search space to a two-dimensional one. We provide experiments with real images showing the good performance of the technique.Comment: 19 pages, 14 figures, 7 tables, J. Math. Imaging Vi

    Researching the Ends of Identity: Birth and Death on Social Media

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    This paper argues that expanding the scope of social media studies to examine birth and early life at one end, and death and memorialisation at the other, demonstrates that social media is never just about an individual, but also the way individuals are always already joined together as families, groups, communities and more. Mapping these ends of identity also reveals more of the nuances of everyday social media use and its impact

    Stories tell us? Political narrative, demes, and the transmission of knowledge through culture

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    This paper compares two institutions of storytelling, mainstream national narratives and self-represented digital storytelling. It considers the centenary of World War 1, especially the Gallipoli campaign (1915) and its role in forming Australian ‘national character’. Using the new approach of cultural science, it investigates storytelling as a means by which cultures make and bind groups or ‘demes’. It finds that that demic (group-made) knowledge trumps individual experience, and that self-representation (digital storytelling) tends to copy the national narrative, even when the latter is known not to be true. The paper discusses the importance of culture in the creation of knowledge, arguing that if the radical potential of digital storytelling is to be understood – and realised – then a systems (as opposed to behavioural) approach to communication is necessary. Without a new model of knowledge, it seems we are stuck with repetition of the same old story
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