1,097 research outputs found

    Geology of the seabed and shallow subsurface: the Irish Sea

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    The British Geological Survey was commissioned by the Crown Estate to assess geological conditions in the Irish Sea in relation to the possible constraints they may place on development of offshore infrastructure. The report describes the geology between 0 m and 50 m below seabed, which is the depth most relevant to current pile foundation technology. The report reviews the best available data from a variety of sources including, BGS legacy data, map sheets, and regional reports, as well as site investigations carried out for hydrocarbon and offshore renewable industries. Additional data collected for the proposed Round 3 offshore wind farm in the Irish Sea (Celtic Array) was also included. Prof. Richard Chiverrell and Dr. Katrien Van Landeghem (of Liverpool and Bangor universities), who together have extensive experience working in the Irish Sea, provided valuable advice and guidance. The report is split into four principle sections as summarised below. Section 3 summarises seabed topography, sediments and processes. The topography of the report area is split into shallow platforms and deeper troughs. Seabed sediments are subdivided into regions of soft mud- (clay and silt) rich sediment in the eastern and western Irish Sea and a central gravel belt comprising coarse sand and gravel. Small areas of bedrock outcrop at seabed are also recognised. Currents in the Irish Sea mobilise sediment to form a collection of marine bedforms ranging from ripples to very large (up to 36 m in height) solitary sediment waves and banner banks. Predicting bedform migration speeds and pathways is difficult and requires repeat surveys. Bedform migration rates of 0 m/yr to 66 m/yr, with average values around 6 m/yr have been observed. Shallow gas is expected in some areas of the Irish Sea. Where this gas is present, pockmarks or methane derived authigenic carbonate may occur. Section 4 summarises the Quaternary history of the Irish Sea and its impact on the distribution, thickness and properties of sediment. Growth and collapse of ice sheets and associated sea level fluctuations principally determine geological properties of Quaternary sediments. The stratigraphy in the report area reflects three major glacial periods with the last one having the most pronounced influence. Very stiff diamicts (glacial ‘boulder clays’ or tills) are present across most of the report area of variable thickness. In enclosed deeps, locally sediment thickness can be >100 m. Glacial landforms are preserved at the seabed and can be used to predict sediment properties. Extensive studies onshore can provide analogues to assess potential geological properties offshore. Section 5 provides a review of bedrock distribution and properties. Where Quaternary sediment cover is <50 m, bedrock will be encountered in the shallow subsurface. The predominant bedrock lithologies in the report area are Triassic and Carboniferous sandstone and mudstone. Geotechnical properties of Triassic rocks are comparable and potentially predictable. Carboniferous rock show high lateral and vertical variability. There are a number of igneous intrusions in the report area and rock properties near to the location of these igneous bodies may differ due to alteration of the host rock during intrusion. Section 6 summarises the geological constraints identified in preceding sections with reference to engineering activities and infrastructure. The report outlines the current state of knowledge of geological conditions in the Irish Sea. It is recommended for use as a guide and should not replace a detailed site investigation

    Using relative sea-level data to constrain the deglacial and Holocene history of southern Greenland

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    This paper presents new Holocene relative sea-level (RSL) data collected from isolation basins close to the town of Paamiut in south west Greenland. The data shows a rapid fall from a marine limit of c. 52 m asl at c. 10.9 cal. ka BP to close to present by c. 9.5 cal. ka BP, at rates of up to c. 32 mm/yr, falling below present for the majority of the Holocene before rising to present in the last 2000 years. The elevation of the RSL lowstand is not well constrained, but was at least below −3 m. This pattern of rapid RSL fall during the early Holocene matches the pattern seen at other southern Greenland locations suggesting rapid, largely simultaneous ice retreat from the area surrounding the Qassimiut Lobe at the start of the Holocene, occurring c. 2000 years after the initial deglaciation of the extreme southern tip of Greenland. The RSL histories from this and other southern Greenland locations are distinct to those recorded further north along the west coast, and are in broad agreement with a pattern of vertical land motion and RSL predicted by the Huy2 model (Simpson et al., 2009), which predicts an 80 m drop in the contribution of vertical land motion to RSL at 10 cal. ka BP between Sisimiut and Paamiut on the west coast. Despite this broad-scale spatial agreement between the RSL data and the Huy2 model, it fails to satisfactorily predict the Holocene RSL histories at Paamiut and other southern Greenland locations. Sensitivity tests indicate that the data-model misfits are most likely due to an over-estimate of the forcing during the Holocene Thermal Maximum (or the response to this forcing) in southern Greenland and error in the North American ice sheets component of the background deglaciation model. Our new data suggests that much of the southern part of the ice sheet acted differently to the area further north. However RSL changes at Paamiut are also largely impacted by regional and larger-scale processes including a bulls-eye of uplift centred on the west, the impact of the Holocene Thermal Maximum and the influence of the collapse of the North American ice sheets

    Crystal structure, magnetic properties, and the magnetocaloric effect of Gd5Rh4 and GdRh

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    The crystal structures of Gd5Rh4 and GdRh have been studied by powder and single crystal x-ray diffraction. The results show that Gd5Rh4 is isotypic with Pu5Rh4 and the bond length of the short Rh-Rh dimer is 2.943(4) Å. According to heat capacity measurements in zero magnetic field, the magnetic ordering temperature of Gd5Rh4 is 13 K, in agreement with magnetization measurements. Both the heat capacity peak shape and the positive slope of the Arrott plots at Curie temperature (TC) indicate the second-order nature of the magnetic transition. The temperature dependence of magnetization of Gd5Rh4 measured in 1 kOe applied field indicates noncollinear magnetic ordering that may change into nearly collinear ferromagnetic ordering by increasing the magnetic field. GdRh is ferromagnetic below T C  = 22 K. Moderate magnetocaloric effects and relatively high refrigerant capacities are observed in Gd5Rh4 and GdRh

    Static quantities of the W boson in the SU_L(3) X U_X(1) model with right-handed neutrinos

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    The static electromagnetic properties of the WW boson, Δκ\Delta \kappa and ΔQ\Delta Q, are calculated in the SU_L(3)} \times U_X(1) model with right-handed neutrinos. The new contributions from this model arise from the gauge and scalar sectors. In the gauge sector there is a new contribution from a complex neutral gauge boson Y0Y^0 and a singly-charged gauge boson Y±Y^\pm. The mass of these gauge bosons, called bileptons, is expected to be in the range of a few hundreds of GeV according to the current bounds from experimental data. If the bilepton masses are of the order of 200 GeV, the size of their contribution is similar to that obtained in other weakly coupled theories. However the contributions to both ΔQ\Delta Q and Δκ\Delta \kappa are negligible for very heavy or degenerate bileptons. As for the scalar sector, an scenario is examined in which the contribution to the WW form factors is identical to that of a two-Higgs-doublet model. It is found that this sector would not give large corrections to Δκ\Delta \kappa and ΔQ\Delta Q.Comment: New material included. Final version to apppear in Physical Review

    On the magnetic stability at the surface in strongly correlated electron systems

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    The stability of ferromagnetism at the surface at finite temperatures is investigated within the strongly correlated Hubbard model on a semi-infinite lattice. Due to the reduced surface coordination number the effective Coulomb correlation is enhanced at the surface compared to the bulk. Therefore, within the well-known Stoner-picture of band ferromagnetism one would expect the magnetic stability at the surface to be enhanced as well. However, by taking electron correlations into account well beyond the Hartree-Fock (Stoner) level we find the opposite behavior: As a function of temperature the magnetization of the surface layer decreases faster than in the bulk. By varying the hopping integral within the surface layer this behavior becomes even more pronounced. A reduced hopping integral at the surface tends to destabilize surface ferromagnetism whereas the magnetic stability gets enhanced by an increased hopping integral. This behavior represents a pure correlation effect and can be understood in terms of general arguments which are based on exact results in the limit of strong Coulomb interaction.Comment: 6 pages, RevTeX, 4 eps figures, accepted (Phys. Rev. B), for related work and info see http://orion.physik.hu-berlin.d

    Slogging and Stumbling Toward Social Justice in a Private Elementary School: The Complicated Case of St. Malachy

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    This case study examines St. Malachy, an urban Catholic elementary school primarily serving children traditionally marginalized by race, class, linguistic heritage, and disability. As a private school, St. Malachy serves the public good by recruiting and retaining such traditionally marginalized students. As empirical studies involving Catholic schools frequently juxtapose them with public schools, the author presents this examination from a different tack. Neither vilifying nor glorifying Catholic schooling, this study critically examines the pursuit of social justice in this school context. Data gathered through a 1-year study show that formal and informal leaders in St. Malachy adapted their governance, aggressively sought community resources, and focused their professional development to build the capacity to serve their increasingly pluralistic student population. The analysis confirms the deepening realization that striving toward social justice is a messy, contradictory, and complicated pursuit, and that schools in both public and private sectors are allies in this pursuit

    The troublesome ticks research protocol: Developing a comprehensive, multidiscipline research plan for investigating human tick-associated disease in Australia

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    In Australia, there is a paucity of data about the extent and impact of zoonotic tick-related illnesses. Even less is understood about a multifaceted illness referred to as Debilitating Symptom Complexes Attributed to Ticks (DSCATT). Here, we describe a research plan for investigating the aetiology, pathophysiology, and clinical outcomes of human tick-associated disease in Australia. Our approach focuses on the transmission of potential pathogens and the immunological responses of the patient after a tick bite. The protocol is strengthened by prospective data collection, the recruitment of two external matched control groups, and sophisticated integrative data analysis which, collectively, will allow the robust demonstration of associations between a tick bite and the development of clinical and pathological abnormalities. Various laboratory analyses are performed including metagenomics to investigate the potential transmission of bacteria, protozoa and/or viruses during tick bite. In addition, multi-omics technology is applied to investigate links between host immune responses and potential infectious and non-infectious disease causations. Psychometric profiling is also used to investigate whether psychological attributes influence symptom development. This research will fill important knowledge gaps about tick-borne diseases. Ultimately, we hope the results will promote improved diagnostic outcomes, and inform the safe management and treatment of patients bitten by ticks in Australia
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