4,832 research outputs found

    Measurements of fast alpha decays in the 100Sn region

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    Exploring the effects of vineyard canopy management practices on soil microbial activity

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    The purpose of the study was to investigate soil fertility and microbial decomposition associated with vineyard canopy management practices which introduce plant litter into the soil. The study specifically focused on the mineralization and immobilization of carbon and nitrogen. In addition, the study also addressed how vineyard fungal disease management influences soil microbial activity. The use of fungicide to limit the presence of fungal disease in the canopy may suppress the vineyard soil’s microbial activity and thus may alter the release of nutrients from the plant litter back into the soil. In addition, soil microbial activity may be increased through residue management.For the study, five plant residue types obtained from a Vitis vinifera hybrid 'Chambourcin' from the Cimarron Valley Research Station in Perkins, Oklahoma, were added to vineyard soil. The plant litter treatments consisted of grapevine pruning (i.e., woody plant material from the dormant period of the grapevine), grapevine leaves and shoots, fruit, and aboveground tissues from two cover crops, wheat, and clover. Additionally, half of the incubation treatments received Mancozeb, a commonly used fungicide in vineyards, to examine the potential effect of viticultural disease management practices on soil microbial populations. Wheat, the highest quality litter in terms of carbon to nitrogen ratio, had the highest amounts of ammonium and nitrate, microbial biomass carbon and cumulative CO2 respiration. Fungicide additions suppressed microbial activity and initially prevented the conversion of nitrate to ammonium. Targeted canopy management in vineyard systems may thus improve soil fertility and provide pathways to more sustainable fertilizer use

    High-dimensional simplexes for supermetric search

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    In a metric space, triangle inequality implies that, for any three objects, a triangle with edge lengths corresponding to their pairwise distances can be formed. The n-point property is a generalisation of this where, for any (n+1) objects in the space, there exists an n-dimensional simplex whose edge lengths correspond to the distances among the objects. In general, metric spaces do not have this property; however in 1953, Blumenthal showed that any semi-metric space which is isometrically embeddable in a Hilbert space also has the n-point property. We have previously called such spaces supermetric spaces, and have shown that many metric spaces are also supermetric, including Euclidean, Cosine, Jensen-Shannon and Triangular spaces of any dimension. Here we show how such simplexes can be constructed from only their edge lengths, and we show how the geometry of the simplexes can be used to determine lower and upper bounds on unknown distances within the original space. By increasing the number of dimensions, these bounds converge to the true distance. Finally we show that for any Hilbert-embeddable space, it is possible to construct Euclidean spaces of arbitrary dimensions, from which these lower and upper bounds of the original space can be determined. These spaces may be much cheaper to query than the original. For similarity search, the engineering tradeoffs are good: we show significant reductions in data size and metric cost with little loss of accuracy, leading to a significant overall improvement in exact search performance

    Aging and the visual perception of exocentric distance

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    AbstractThe ability of 18 younger and older adults to visually perceive exocentric distances was evaluated. The observers judged the extent of fronto-parallel and in-depth spatial intervals at a variety of viewing distances from 50cm to 164.3cm. Most of the observers perceived in-depth intervals to be significantly smaller than fronto-parallel intervals, a finding that is consistent with previous studies. While none of the individual observers’ judgments of exocentric distance were accurate, the judgments of the older observers were significantly more accurate than those of the younger observers. The precision of the observers’ judgments across repeated trials, however, was not affected by age. The results demonstrate that increases in age can produce significant improvements in the visual ability to perceive the magnitude of exocentric distances

    A photographic essay on landslides across southeastern New South Wales triggered by the rainfall events of 2022

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    Eastern Australia has experienced a significant magnitude rainfall event of extended duration in the first 7 months of 2022. Across the east coast of New South Wales (NSW) a series of troughs and East Coast Lows occurred during a La Nina weather cycle bringing above average rainfall to the region. As this first half of 2022 La Nina event was drawing to a close the Indian Ocean Dipole entered a negative phase which coincided with another intense East Coast Low in early July 2022 impacting the Illawarra region of NSW. These events caused widespread flooding and significant landslide damage to road and rail infrastructure across the state networks and local government infrastructure across NSW. During this extended wet period in the first 7 months of 2022 more than 200 landslides have been recorded across the Illawarra, Southern Highlands and Blue Mountains regions of NSW whilst many more have occurred across the north coast region. This paper presents a brief and albeit preliminary summary of the rainfall and provides a series of photographs with very brief descriptions of some of these landslide events within southeastern NSW. The intent of the paper is to provide early guidance to AGS members of the nature and form of landslides that have occurred across the Illawarra region. This paper does not discuss the dual fatality resulting from the Wentworth Falls area rockfall of the 5th April

    Theory and numerical evaluation of oddoids and evenoids: Oscillatory cuspoid integrals with odd and even polynomial phase functions

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    The properties of oscillating cuspoid integrals whose phase functions are odd and even polynomials are investigated. These integrals are called oddoids and evenoids, respectively (and collectively, oddenoids). We have studied in detail oddenoids whose phase functions contain up to three real parameters. For each oddenoid, we have obtained its Maclaurin series representation and investigated its relation to Airy-Hardy integrals and Bessel functions of fractional orders. We have used techniques from singularity theory to characterise the caustic (or bifurcation set) associated with each oddenoid, including the occurrence of complex whiskers. Plots and short tables of numerical values for the oddenoids are presented. The numerical calculations used the software package CUSPINT [N.P. Kirk, J.N.L. Connor, C.A. Hobbs, An adaptive contour code for the numerical evaluation of the oscillatory cuspoid canonical integrals and their derivatives, Comput. Phys. Commun. 132 (2000) 142-165]. © 2006 Elsevier B.V. All rights reserved

    In-Vivo Evaluation of Microultrasound and Thermometric Capsule Endoscopes

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    Clinical endoscopy and colonoscopy are commonly used to investigate and diagnose disorders in the upper gastrointestinal tract and colon respectively. However, examination of the anatomically remote small bowel with conventional endoscopy is challenging. This and advances in miniaturization led to the development of video capsule endoscopy (VCE) to allow small bowel examination in a non-invasive manner. Available since 2001, current capsule endoscopes are limited to viewing the mucosal surface only due to their reliance on optical imaging. To overcome this limitation with submucosal imaging, work is under way to implement microultrasound (μUS) imaging in the same form as VCE devices. This paper describes two prototype capsules, termed Sonocap and Thermocap, which were developed respectively to assess the quality of μUS imaging and the maximum power consumption that can be tolerated for such a system. The capsules were tested in vivo in the oesophagus and small bowel of porcine models. Results are presented in the form of μUS B-scans and safe temperature readings observed up to 100 mW in both biological regions. These results demonstrate that acoustic coupling and μUS imaging can be achieved in vivo in the lumen of the bowel and the maximum power consumption that is possible for miniature μUS systems

    Translational trial outcomes for capsule endoscopy test devices

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    Current clinical standards in the endoscopic diagnosis of gastrointestinal diseases are primarily based on the use of optical systems. Ultrasound has established diagnostic credibility in the form of endoscopic ultrasound (EUS), however it is limited to examination of the upper gastrointestinal tract (oesophagus, stomach and upper (proximal) small bowel). Access to the remainder of the small bowel is currently limited to optical capsule endoscopes and a limited number of other modalities as these capsules are restricted to visual examination of the surface or mucosa of the gut wall. Ultrasound capsule endoscopy has been proposed to integrate microultrasound imaging capabilities into the existing capsule format and extend examination capabilities beyond the mucosa. To establish the ability of high frequency ultrasound to resolve the histological structure of the gastrointestinal tract, ex vivo scans of pig and human tissue were performed. This was done using 25 and 34 MHz single element, physically focused composite transducers mechanically scanned along the tissue. Tethered prototype devices were then developed with 30 MHz physically focused polyvinylidene fluoride (PVDF) single element transducers embedded for use in initial translational trials in the small bowel of porcine subjects. B-scan images from the ex vivo model validation and the in vivo trials are presented

    Estimating the frequency of volcanic ash clouds over northern Europe

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    Fine ash produced during explosive volcanic eruptions can be dispersed over a vast area, where it poses a threat to aviation, human health and infrastructure. Here, we focus on northern Europe, which lies in the principal transport direction for volcanic ash from Iceland, one of the most active volcanic regions in the world. We interrogate existing and newly produced geological and written records of past ash fallout over northern Europe in the last 1000 years and estimate the mean return (repose) interval of a volcanic ash cloud over the region to be 44 ± 7 years. We compare tephra records from mainland northern Europe, Great Britain, Ireland and the Faroe Islands, with records of proximal Icelandic volcanism and suggest that an Icelandic eruption with a Volcanic Explosivity Index rating (VEI) ≥ 4 and a silicic magma composition presents the greatest risk of producing volcanic ash that can reach northern Europe. None of the ash clouds in the European record which have a known source eruption are linked to a source eruption with VEI < 4. Our results suggest that ash clouds are more common over northern Europe than previously proposed and indicate the continued threat of ash deposition across northern Europe from eruptions of both Icelandic and North American volcanoes

    LPS Responsiveness and Neutrophil Chemotaxis In Vivo Require PMN MMP-8 Activity

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    We identify matrix metalloproteinase (MMP)-8, the polymorphonuclear (PMN) leukocyte collagenase, as a critical mediator initiating lipopolysaccharide (LPS)-responsiveness in vivo. PMN infiltration towards LPS is abrogated in Mmp8-null mice. MMP-8 cleaves LPS-induced CXC chemokine (LIX) at Ser(4)∼Val(5) and Lys(79)∼Arg(80). LIX bioactivity is increased upon N-terminal cleavage, enhancing intracellular calcium mobilization and chemotaxis upon binding its cognate receptor, CXCR2. As there is no difference in PMN chemotaxis in Mmp8-null mice compared with wild-type mice towards synthetic analogues of MMP-8-cleaved LIX, MMP-8 is not essential for extravasation or cell migration in collagenous matrices in vivo. However, with biochemical redundancy between MMPs 1, 2, 9, and 13, which also cleave LIX at position 4∼5, it was surprising to observe such a markedly reduced PMN infiltration towards LPS and LIX in Mmp8-/- mice. This lack of physiological redundancy in vivo identifies MMP-8 as a key mediator in the regulation of innate immunity. Comparable results were found with CXCL8/IL-8 and CXCL5/ENA-78, the human orthologues of LIX. MMP-8 cleaves CXCL8 at Arg(5)-Ser(6) and at Val(7)-Leu(8) in CXCL5 to activate respective chemokines. Hence, rather than collagen, these PMN chemoattractants are important MMP-8 substrates in vivo; PMN-derived MMP-8 cleaves and activates LIX to execute an in cis PMN-controlled feed-forward mechanism to orchestrate the initial inflammatory response and promote LPS responsiveness in tissue
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