2,018 research outputs found

    Radio continuum observations of Class I protostellar disks in Taurus: constraining the greybody tail at centimetre wavelengths

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    We present deep 1.8 cm (16 GHz) radio continuum imaging of seven young stellar objects in the Taurus molecular cloud. These objects have previously been extensively studied in the sub-mm to NIR range and their SEDs modelled to provide reliable physical and geometrical parametres.We use this new data to constrain the properties of the long-wavelength tail of the greybody spectrum, which is expected to be dominated by emission from large dust grains in the protostellar disk. We find spectra consistent with the opacity indices expected for such a population, with an average opacity index of beta = 0.26+/-0.22 indicating grain growth within the disks. We use spectra fitted jointly to radio and sub-mm data to separate the contributions from thermal dust and radio emission at 1.8 cm and derive disk masses directly from the cm-wave dust contribution. We find that disk masses derived from these flux densities under assumptions consistent with the literature are systematically higher than those calculated from sub-mm data, and meet the criteria for giant planet formation in a number of cases.Comment: submitted MNRA

    Using natural means to reduce surface transport noise during propagation outdoors

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    This paper reviews ways of reducing surface transport noise by natural means. The noise abatement solutions of interest can be easily (visually) incorporated in the landscape or help with greening the (sub)urban environment. They include vegetated surfaces (applied to faces or tops of noise walls and on building façades and roofs ), caged piles of stones (gabions), vegetation belts (tree belts, shrub zones and hedges), earth berms and various ways of exploiting ground-surface-related effects. The ideas presented in this overview have been tested in the laboratory and/or numerically evaluated in order to assess or enhance the noise abatement they could provide. Some in-situ experiments are discussed as well. When well-designed, such natural devices have the potential to abate surface transport noise, possibly by complementing and sometimes improving common (non-green) noise reducing devices or measures. Their applicability strongly depends on the available space reserved for the noise abatement and the receiver position

    Effect of natalizumab on disease progression in secondary progressive multiple sclerosis (ASCEND). a phase 3, randomised, double-blind, placebo-controlled trial with an open-label extension

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    Background: Although several disease-modifying treatments are available for relapsing multiple sclerosis, treatment effects have been more modest in progressive multiple sclerosis and have been observed particularly in actively relapsing subgroups or those with lesion activity on imaging. We sought to assess whether natalizumab slows disease progression in secondary progressive multiple sclerosis, independent of relapses. Methods: ASCEND was a phase 3, randomised, double-blind, placebo-controlled trial (part 1) with an optional 2 year open-label extension (part 2). Enrolled patients aged 18–58 years were natalizumab-naive and had secondary progressive multiple sclerosis for 2 years or more, disability progression unrelated to relapses in the previous year, and Expanded Disability Status Scale (EDSS) scores of 3·0–6·5. In part 1, patients from 163 sites in 17 countries were randomly assigned (1:1) to receive 300 mg intravenous natalizumab or placebo every 4 weeks for 2 years. Patients were stratified by site and by EDSS score (3·0–5·5 vs 6·0–6·5). Patients completing part 1 could enrol in part 2, in which all patients received natalizumab every 4 weeks until the end of the study. Throughout both parts, patients and staff were masked to the treatment received in part 1. The primary outcome in part 1 was the proportion of patients with sustained disability progression, assessed by one or more of three measures: the EDSS, Timed 25-Foot Walk (T25FW), and 9-Hole Peg Test (9HPT). The primary outcome in part 2 was the incidence of adverse events and serious adverse events. Efficacy and safety analyses were done in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT01416181. Findings: Between Sept 13, 2011, and July 16, 2015, 889 patients were randomly assigned (n=440 to the natalizumab group, n=449 to the placebo group). In part 1, 195 (44%) of 439 natalizumab-treated patients and 214 (48%) of 448 placebo-treated patients had confirmed disability progression (odds ratio [OR] 0·86; 95% CI 0·66–1·13; p=0·287). No treatment effect was observed on the EDSS (OR 1·06, 95% CI 0·74–1·53; nominal p=0·753) or the T25FW (0·98, 0·74–1·30; nominal p=0·914) components of the primary outcome. However, natalizumab treatment reduced 9HPT progression (OR 0·56, 95% CI 0·40–0·80; nominal p=0·001). In part 1, 100 (22%) placebo-treated and 90 (20%) natalizumab-treated patients had serious adverse events. In part 2, 291 natalizumab-continuing patients and 274 natalizumab-naive patients received natalizumab (median follow-up 160 weeks [range 108–221]). Serious adverse events occurred in 39 (13%) patients continuing natalizumab and in 24 (9%) patients initiating natalizumab. Two deaths occurred in part 1, neither of which was considered related to study treatment. No progressive multifocal leukoencephalopathy occurred. Interpretation: Natalizumab treatment for secondary progressive multiple sclerosis did not reduce progression on the primary multicomponent disability endpoint in part 1, but it did reduce progression on its upper-limb component. Longer-term trials are needed to assess whether treatment of secondary progressive multiple sclerosis might produce benefits on additional disability components. Funding: Biogen

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    The Forest Observation System, building a global reference dataset for remote sensing of forest biomass

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    International audienceForest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (aGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. aGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world's forests. all plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities

    Plastics in the environment in the context of UV radiation, climate change and the Montreal Protocol: UNEP Environmental Effects Assessment Panel, Update 2023

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    This Assessment Update by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) considers the interactive effects of solar UV radiation, global warming, and other weathering factors on plastics. The Assessment illustrates the significance of solar UV radiation in decreasing the durability of plastic materials, degradation of plastic debris, formation of micro- and nanoplastic particles and accompanying leaching of potential toxic compounds. Micro- and nanoplastics have been found in all ecosystems, the atmosphere, and in humans. While the potential biological risks are not yet well-established, the widespread and increasing occurrence of plastic pollution is reason for continuing research and monitoring. Plastic debris persists after its intended life in soils, water bodies and the atmosphere as well as in living organisms. To counteract accumulation of plastics in the environment, the lifetime of novel plastics or plastic alternatives should better match the functional life of products, with eventual breakdown releasing harmless substances to the environment

    United Nations Environment Programme (UNEP), Plastics in the environment in the context of UV radiation, climate change and the Montreal Protocol. 2023 Assessment Update of the UNEP Environmental Effects Assessment Panel

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    Solar ultraviolet radiation is a contributing factor in the environmental fate of toxic chemicals and other contaminants, with consequences that may be either beneficial or detrimental for the health of humans and the environment. This Assessment Update (2023) by the Environmental Effects Assessment Panel (EEAP) focusses on the role and significance of UV radiation and associated drivers on the breakdown of plastic waste in the environment. Plastic is a ubiquitous pollutant. UV radiation and mechanical stress drive the degradation and fragmentation of larger plastic waste into smaller micro- and nanoplastics. The Assessment Update considers the interactive effects of UV radiation and climate change on plastic durability, weathering, longevity, and ultimately the fate of plastic debris

    Proceedings of the Fourth Caldwell Conference, St. Catherines Island, Georgia, March 27-29, 2009.

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    391 p. : ill. (chiefly col.), maps (chiefly col.) ; 26 cm. "Issued March 23, 2011."This edited volume addresses the geoarchaeology of St. Catherines Island (Georgia). The field of geoarchaeology has typically been defined as either geology pursued within an archaeological framework or (sometimes the reverse) as archaeology framed with the help of geological methodology. Either way, the formalized objectives of geoarchaeology define a broad range of pursuits, from placing archaeological sites into relative and absolute temporal context through the application of stratigraphic principles and absolute dating techniques, to understanding the natural processes of site formation, to reconstructing the landscapes that existed around a site or group of sites at the time of occupation. The editors of this volume have generally followed the lead of G.R. Rapp and C.L. Hill (2006, Geoarchaeology : the earth-science approach to archaeological interpretation) by stressing the importance of multiple viewpoints and methodologies in applying geoscience techniques to evaluate the archaeological record. In the broadest sense, then, Geoarchaeology of St. Catherines Island applies multiple earth science concepts, techniques, or knowledge bases to the known archaeological record and the processes that created that record. This volume consists of 16 papers presenting the newest research on the stratigraphic and geomorphological evolution of the St. Catherines Island landscape. Of particular interest are presentations addressing the relative timing and nature of sedimentation, paleobiology, sea level change, stream capture, hydrology, and erosional patterning evident on St. Catherines Island (and to some degree the rest of the Georgia Bight). These papers were initially presented at the Fourth Caldwell Conference, cosponsored by the American Museum of Natural History and the St. Catherines Island Foundation, held on St. Catherines Island (Georgia), March 27-29, 2009. Table of contents: Why this archaeologist cares about geoarchaeology : some pasts and futures of St. Catherines Island / David Hurst Thomas -- Evolution of late Pleistocene-Holocene climates and environments of St. Catherines Island and the Georgia Bight / Fredrick J. Rich, Anthony Vega, and Frank J. Vento -- Geoarchaeological research at St. Catherines Island : defining the geological foundation / Gale A. Bishop, Brian K. Meyer, R. Kelly Vance, and Fredrick J. Rich -- Development of a late Pleistocene-Holocene genetic stratigraphic framework for St. Catherines Island : archaeological implications / Frank J. Vento and Patty A. Stahlman -- Ichnological diagnosis of ancient storm-washover fans, Yellow Banks Bluff, St. Catherines Island / Anthony J. Martin and Andrew K. Rindsberg -- Quaternary vegetation and depositional history of St. Catherines Island / Fredrick J. Rich and Robert K. Booth -- Recent shoreline erosion and vertical accretion patterns, St. Catherines Island / Donald B. Potter Jr. -- Role of storm events in beach ridge formation, St. Catherines Island / Harold B. Rollins, Kathi Beratan, and James E. Pottinger -- Drainage changes at Ossabaw, St. Catherines, and Sapelo sounds and their influence on island morphology and spit building on St. Catherines Island / Timothy M. Chowns -- Vibracores and vibracore transects : constraining the geological and cultural history of St. Catherines Island / Gale A. Bishop, David Hurst Thomas, Matthew C. Sanger, Brian K. Meyer, R. Kelly Vance, Robert K. Booth, Fredrick J. Rich, Donald B. Potter, and Timothy Keith-Lucas -- Application of ground penetrating radar to investigations of the stratigraphy, structure, and hydrology of St. Catherines Island / R. Kelly Vance, Gale A. Bishop, Fredrick J. Rich, Brian K. Meyer, and Eleanor J. Camann -- Postsettlement dispersal and dynamic repopulation of estuarine habitats by adult Mercenaria mercenaria, St. Catherines Island / Robert S. Prezant, Harold B. Rollins, and Ronald B. Toll -- The foundation for sea turtle geoarchaeology and zooarchaeology : morphology of recent and ancient sea turtle nests, St. Catherines Island, Georgia, and Cretaceous Fox Hills Sandstone, Elbert County, Colorado / Gale A. Bishop, Fredric L. Pirkle, Brian K. Meyer, and William A. Pirkle -- Sea turtle habitat deterioration on St. Catherines Island : defining the modern transgression / Gale A. Bishop and Brian K. Meyer -- Modeling indigenous hunting and harvesting of sea turtles and their eggs on the Georgia Coast / Gale A. Bishop, David Hurst Thomas, and Brian K. Meyer -- Geomorphology, sea level, and marine resources : St. Catherines Island / Harold B. Rollins and David Hurst Thomas -- Appendix 1. Noncultural radiocarbon record from St. Catherines Island : a compendium -- Appendix 2. Vibracore record from St. Catherines Island : a compendium.Conference sponsored by the American Museum of Natural History and the St. Catherines Island Foundation

    CropPol: a dynamic, open and global database on crop pollination

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    Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA). This article is protected by copyright. All rights reserved
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