99 research outputs found

    Vertical Changes of Recent Ostracode Assemblages and Environment in the Inner Part of Jakarta Bay, Indonesia

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    A short sediment core from the inner part of Jakarta Bay, Indonesia, was quantitatively analysed for ostracods (minute Crustacea), total organic carbon (TOC) and total nitrogen (TN) contents, and the vertical distributions were recorded. A total of 53 ostracod species were obtained from 80 continuous core samples. The dominant species were Keijella carriei and Loxoconcha wrighti, which are common in areas with high TOC and TN contents. Based on an analysis of ostracod assemblages and carbon/nitrogen ratio, the study site began to be influenced by organic contamination from around 1950. Although the population of Jakarta City has increased rapidly since then, TOC and TN contents which were low, have gradually increased (0.7%–0.9% and 0.10%–0.12%, respectively), probably due to addition of nutrients from river sedimentation. The increased sedimentation rate after 1950 resulted in an increasing TOC ratio. The observed correlation between TOC and dominant species shows that Phlyctenophora orientalis may be a good indicator for monitoring increases in the narrow TOC content range of 0.7%–1.1%

    Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings

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    A. Forest et al. -- 78 pages, 18 figures, 6 tablesA better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here, we combine mooring times-series, ship-based measurements and remote-sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their biophysical determinants in summer. Flux data were obtained with sediment traps and via a regional empirical algorithm applied to particle size-distributions (17 classes from 0.08–4.2 mm) measured by an Underwater Vision Profiler 5. Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e. principal coordinates of neighbor matrices, PCNM), were conducted to partition the variation of POC flux size-classes. Flux variability was explained at 69.5 % by the addition of a linear temporal trend, 7 significant PCNM and 9 biophysical variables. The interaction of all these factors explained 27.8 % of the variability. The first PCNM canonical axis (44.4 % of spatial variance) reflected a shelf-basin gradient controlled by bottom depth and ice concentration (p < 0.01), but a complex assemblage of fine-to-broad scale patterns was also identified. Among biophysical parameters, bacterial production and northeasterly wind (upwelling-favorable) were the two strongest explanatory variables (r2 cum. = 0.37), suggesting that bacteria were associated with sinking material, which was itself partly linked to upwelling-induced productivity. The second most important spatial structure corresponded actually to the two areas where shelf break upwelling is known to occur under easterlies. Copepod biomass was negatively correlated (p < 0.05) with vertical POC fluxes, implying that metazoans played a significant role in the regulation of export fluxes. The low fractal dimension of settling particles (1.26) and the high contribution (~94 %) of fast-sinking small aggregates (<1 mm; 20–30 m d−1) to the mass fluxes suggested that settling material across the region was overall fluffy, porous, and likely resulting from the aggregation of marine detritus, gel-like substances and ballast minerals. Our study demonstrates that vertical POC fluxes in Arctic shelf systems are spatially complex, sensitive to environmental forcings, and determined by both physicochemical mechanisms and food web functioning. In conclusion, we hypothesize that the incorporation of terrestrial matter into the Beaufort Sea food web could be catalyzed by bacteria via the incorporation of dissolved terrestrial carbon liberated through the photo-cleavage and/or hydrolysis of land-derived POC interweaved with marine aggregatesThis work would not have been possible without the professional and enthusiastic assistance of the officers and crew members of the CCGS Amundsen. We express gratitude to L. Prieur and C. Marec for their help in the deployment of the CTD-rosette and for the onboard processing of UVP5 data. We thank J. Martin, J. Gagnon, A. Mignot and M. Gosselin for sharing the chlorophyll data in order to post-calibrate the fluorometer. 5 We thank P. Guillot for the validation of physical data. We thank M. Fortier, K. L´evesque and J. Ehn for the organization of the fieldwork, workshops and for support at sea. This study was conducted as part of the Malina Scientific Program funded by ANR (Agence nationale de la recherche), INSU-CNRS (Institut national des sciences de l’univers – Centre national de la recherche scientifique), CNES (Centre national d’e´tudes spatiales) and ESA (European Space Agency). Additional support from ArcticNet (a Network of Centres of Excellence of Canada) and from the ArcticNet-Imperial Oil Research Collaboration was welcomed and appreciated. The IAEA is grateful to the Government of the Principality of Monaco for the support provided to its Environment Laboratories. This work is a joint contribution to the Malina Project and to the research 15 programs of Que´bec-Oce´an, ArcticNet, the Takuvik Joint U. Laval/CNRS Laboratory, the Arctic in Rapid Transition (ART) Initiative, to the Canada Research Chair on the Response of Marine Arctic Ecosystems to ClimateWarming, and to the Canada Excellence Research Chair (CERC) in Remote Sensing of Canada’s New Arctic FrontierPeer reviewe

    Anthropometry and body composition in ethnic Japanese and Caucasian adolescent girls: Considerations on ethnicity and menarche

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    Objective: This study aimed to compare the various anthropometric and body composition parameters based on the ethnicity and the absence or presence of menarche.Design: A cross-sectional study with incomplete sampling, using the subject as the evaluation unit.Subjects: the final sample of 550 subjects was composed of 122 Japanese and 179 Caucasian premenarcheal adolescents, and 72 Japanese and 177 Caucasian postmenarcheal adolescents.Methods: the variables of body composition were measured through the following methods: bioelectrical impedance analysis, near-infrared interactance (NIR), Slaughter cutaneous skinfold equations and body mass index. Weight, height and sitting height were also evaluated.Results: the Japanese pre- and postmenarcheal girls presented lower weight and height values when compared with the Caucasian girls. in general, the Japanese premenarcheal girls presented less fat and fat-free mass than the premenarcheal Caucasian girls. This fact was demonstrated through NIR results. Conversely, the Japanese postmenarcheal adolescents accumulated more fat than their Caucasian counterparts. However, significant differences were solely encountered in the values of cutaneous skinfold percent body fat. With regard to menarche, it was verified that, regardless of ethnicity, all the anthropometric and body composition variables reached higher values among postmenarcheal adolescents when compared with premenarcheal adolescents.Conclusion: Different results of weight and height between the ethnic groups may bring back the discussion concerning separate growth curves for different ethnic groups. the results of the body composition analysis indicated high adiposity levels among postmenarcheal adolescents.Universidade Federal de São Paulo, Escola Paulista Med, Dept Postgrad Nutr, BR-04020060 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Prevent Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Postgrad Nutr, BR-04020060 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Prevent Med, São Paulo, BrazilWeb of Scienc

    A Large Hadron Electron Collider at CERN

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    This document provides a brief overview of the recently published report on the design of the Large Hadron Electron Collider (LHeC), which comprises its physics programme, accelerator physics, technology and main detector concepts. The LHeC exploits and develops challenging, though principally existing, accelerator and detector technologies. This summary is complemented by brief illustrations of some of the highlights of the physics programme, which relies on a vastly extended kinematic range, luminosity and unprecedented precision in deep inelastic scattering. Illustrations are provided regarding high precision QCD, new physics (Higgs, SUSY) and electron-ion physics. The LHeC is designed to run synchronously with the LHC in the twenties and to achieve an integrated luminosity of O(100) fb1^{-1}. It will become the cleanest high resolution microscope of mankind and will substantially extend as well as complement the investigation of the physics of the TeV energy scale, which has been enabled by the LHC

    A Large Hadron Electron Collider at CERN

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    The physics programme and the design are described of a new collider for particle and nuclear physics, the Large Hadron Electron Collider (LHeC), in which a newly built electron beam of 60 GeV, to possibly 140 GeV, energy collides with the intense hadron beams of the LHC. Compared to the first ep collider, HERA, the kinematic range covered is extended by a factor of twenty in the negative four-momentum squared, Q2, and in the inverse Bjorken x, while with the design luminosity of 1033 cm-2 s-1 the LHeC is projected to exceed the integrated HERA luminosity by two orders of magnitude. The physics programme is devoted to an exploration of the energy frontier, complementing the LHC and its discovery potential for physics beyond the Standard Model with high precision deep inelastic scattering measurements. These are designed to investigate a variety of fundamental questions in strong and electroweak interactions. The LHeC thus continues the path of deep inelastic scattering (DIS) into unknown areas of physics and kinematics. The physics programme also includes electron-deuteron and electron-ion scattering in a (Q21/x) range extended by four orders of magnitude as compared to previous lepton-nucleus DIS experiments for novel investigations of neutron's and nuclear structure, the initial conditions of Quark-Gluon Plasma formation and further quantum chromodynamic phenomena. The LHeC may be realised either as a ring-ring or as a linac-ring collider. Optics and beam dynamics studies are presented for both versions, along with technical design considerations on the interaction region, magnets including new dipole prototypes, cryogenics, RF, and further components. A design study is also presented of a detector suitable to perform high precision DIS measurements in a wide range of acceptance using state-of-the art detector technology, which is modular and of limited size enabling its fast installation. The detector includes tagging devices for electron, photon, proton and neutron detection near to the beam pipe. Civil engineering and installation studies are presented for the accelerator and the detector. The LHeC can be built within a decade and thus be operated while the LHC runs in its high-luminosity phase. It so represents a major opportunity for progress in particle physics exploiting the investment made in the LHC
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