Hydrology of the Barbados Ridge complex, Lesser Antillies [sic] accretionary complex

The Barbados Ridge Complex is the easternmost portion of the Lesser Antillies Subduction Complex. At the deformation front forming its eastern boundary sediment is scraped off of the Atlantic Plate and accreted to the Caribbean Plate. Seismic profiles show that the sediments comprising the Barbados Ridge Complex are divided into an upper, deformed sequence and a lower, layered sequence seperated by a decollement. In attempts to penetrate the decollement DSDP Leg 78A and ODP Leg 110 encountered high pore fluid pressures, temperatures and methane concentrations. Pressures of up to 350 psi and 20.4°C were encountered at Sites 542 and 541, respectively. As the sediments are accreted to the overriding plate tectonic compression forces dewatering of the earliest accreted sediments. Due to the low permeability of the oceanic muds and clays, water is expelled along the decollement and thrust faults splaying from it. This water transmits heat from within the prism to the sediment-water interface. This expelled pore fluid concentrates thermogenic methane along these conduits, where oxidation of the methane within the sulfate reducing zone causes the precipitation of carbonates. As a byproduct hydrogen sulfide is produce, implying the possible existence of vent communities similar to those reported .off the Oregon coast.No embarg

An Extraordinary Scattered Broad Emission Line in a Type 2 QSO

An infrared-selected, narrow-line QSO has been found to exhibit an extraordinarily broad Halpha emission line in polarized light. Both the extreme width (35,000 km/sec full-width at zero intensity) and 3,000 km/sec redshift of the line centroid with respect to the systemic velocity suggest emission in a deep gravitational potential. An extremely red polarized continuum and partial scattering of the narrow lines at a position angle common to the broad-line emission imply extensive obscuration, with few unimpeded lines of sight to the nucleus.Comment: 4 pages, 1 figure, to appear in the Astrophysical Journal Letter

Placing the university: thinking in and beyond globalization

In some respects, the impact of globalization on universities is well rehearsed (competition for international students; the drive for status in global rankings; the opening of overseas campuses; the dream of massive open online courses and other forms of digital education), but the relationship between universities as place-based institutions and globalization is less well understood. It is on that this chapter focuses. Drawing on work undertaken as part of an Economic and Social Research Council project (“Higher Education and Regional Social Transformation”) the author sets the arguments in a wider context. He explores the extent to which and ways in which universities have become key players in the reimagination of their city regions in a (neoliberal) global context. As well as reflecting on the wider public (and local) role of universities, he also considers how universities use the tools available to them to position themselves effectively as successful businesses within the new world in which they find themselves

Influence of coral and algal exudates on microbially mediated reef metabolism.

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs

Palladium-catalysed alkene difunctionalisation in the synthesis of heterocycles

The opening chapter of this thesis is split in two with part one providing a summary of the existing methods for palladium-catalysed oxypalladation reactions resulting in the synthesis of oxygen containing heterocycles. Part two focuses on a niche area of palladium catalysis. Here, palladium-catalysed isohypsic reactions, in which the oxidation state of the palladium does not change throughout the entire catalytic cycle, are described and summarised. Chapter 2 describes the extension of the heteroallylation reaction to incorporate the synthesis of lactones and the pursuit of an enantioselective oxyallylation reaction. The oxyallylation reaction in the synthesis of lactones was successfully applied to include five- and six- membered lactone rings in good yields, with the first enantioselective oxyallylation reaction being developed. Building upon this work, a copper-mediated oxyallylation reaction was developed. Additionally, a palladium-catalysed arylallylation reaction and C-H−cyclisation reaction were pursued. Ensuing work, detailed in chapter 3, focused on the development of a novel isohypsic−redox sequence, combining both the palladium-catalysed isohypsic heteroallylation reaction with more traditional redox chemistry. The transformations developed give rise to the synthesis of heterocycles with complex functionality both quickly and efficiently using the one palladium source. Experimental procedures and data are summarised in Chapter 4

The ferroelectric transition in YMnO3_3 from first principles

We have studied the structural phase transition of multiferroic YMnO$_3$ from first principles. Using group-theoretical analysis and first-principles density functional calculations of the total energy and phonons, we perform a systematic study of the energy surface around the prototypic phase. We find a single instability at the zone-boundary which couples strongly to the polarization. This coupling is the mechanism that allows multiferroicity in this class of materials. Our results imply that YMnO$_3$ is an improper ferroelectric. We suggest further experiments to clarify this point.Comment: published version, PRB (rapid comm), slight change in presentatio

Report of the direct infrared sensors panel

The direct infrared sensors panel considered a wide range of options for technologies relevant to the science goals of the Astrotech 21 mission set. Among the technologies assessed are: large format arrays; photon counting detectors; higher temperature 1 to 10 micro-m arrays; impurity band conduction (IBC) or blocked impurity band (BIB) detectors; readout electronics; and adapting the Space Infrared Telescope Facility and Hubble Space Telescope. Detailed development plans were presented for each of these technology areas