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Oxygen in seawater is a key parameter for the development oflife; changes in dissolved O2 concentrations throughout thePhanerozoic have played a major role in the evolution of marineecosystem s through com plex interactions with dissolvednutrients. However, the precise timing and magnitude of@uctuations in global ocean oxygenation in the past remainpoorly constrained. U stable isotope compositions recorded in marine anoxicsedim ents m ay be used to reconstruct the global extent of m arineanoxia due to their sensitivity to the rem oval @ux of reducedU(IV) from seawater. Nonetheless, it is critical to understandlocal sedim entary processes and their im pact on U isotopefractionation before any global redox inform ation can be inferredfrom A238U variations in the sediments. In particular, previousstudies have suggested that U isotopes could be fractionated byorganic matter in the water column, and that this process mightaCect the isotope value recorded in the sedim ent [1,2]. In this w ork, w e explore the im pact of organic m atter onA238U values measured in Arctic Ocean sediments (IODPExpedition 302) deposited during the Early to Middle Eocene(~56–46 M a), a period characterised by strong hydrographicrestriction and high productivity in the A rctic basin.[1] Holmden, Amini & François (2015), Geochimica etCosmochimica Acta153, 202-215. [2] Hinojosa, Stirling, Reid,Moy & Wilson (2016), Geochimica et Cosmochimica Acta179,89-109

Large igneous provinces (LIPs) are proposed to have caused a number of episodes of abrupt environmental change by increasing atmospheric CO2 levels, which were subsequently alleviated by drawdown of CO2 via enhanced continental weathering and burial of organic matter. Here the sedimentary records of two such episodes of environmental change, the Toarcian oceanic anoxic event (T-OAE) and preceding Pliensbachian–Toarcian (Pl-To) event (both possibly linked to the Karoo-Ferrar LIP), are investigated using a new suite of geochemical proxies that have not been previously compared. Stratigraphic variations in osmium isotope (187Os/188Os) records are compared with those of mercury (Hg) and carbon isotopes (d13C) in samples from the Mochras core, Llanbedr Farm, Cardigan Bay Basin, Wales. These sedimentary rocks are confirmed as recording an open-marine setting by analysis of molybdenum/uranium enrichment trends, indicating that the Os isotope record in these samples reflects the isotopic composition of the global ocean. The Os isotope data include the first results across the Pl-To boundary, when seawater 187Os/188Os increased from ~0.40 to ~0.53, in addition to new data that show elevated 187Os/188Os (from ~0.42 to ~0.68) during the T-OAE. Both increases in 187Os/188Os correlate with negative carbon isotope excursions and increased mercury concentrations, supporting an interplay between terrestrial volcanism, weathering, and climate that was instrumental in driving these distinct episodes of global environmental change. These observations also indicate that the environmental impact of the Karoo-Ferrar LIP was not limited solely to the T-OAE.

Background Exercise has been shown to be beneficial for selected patients with heart failure, but questions remain over its effectiveness, cost-effectiveness and uptake in a real world setting. This paper describes the design, rationale and recruitment for a randomised controlled trial that will explore the effectiveness and uptake of a predominantly home-based exercise rehabilitation programme, as well as its cost-effectiveness and patient acceptability. Methods/design Randomised controlled trial comparing specialist heart failure nurse care plus a nurse-led predominantly home-based exercise intervention against specialist heart failure nurse care alone in a multiethnic city population, served by two NHS Trusts and one primary care setting, in the United Kingdom. 169 English speaking patients with stable heart failure, defined as systolic impairment (ejection fraction ≤ 40%). with one or more hospital admissions with clinical heart failure or New York Heart Association (NYHA) II/III within previous 24-months were recruited. Main outcome measures at 1 year: Minnesota Living with Heart Failure Questionnaire, incremental shuttle walk test, death or admission with heart failure or myocardial infarction, health care utilisation and costs. Interviews with purposive samples of patients to gain qualitative information about acceptability and adherence to exercise, views about their treatment, self-management of their heart failure and reasons why some patients declined to participate. The records of 1639 patients managed by specialist heart failure services were screened, of which 997 (61%) were ineligible, due to ejection fraction>40%, current NYHA IV, no admission or NYHA II or more within the previous 2 years, or serious co-morbidities preventing physical activity. 642 patients were contacted: 289 (45%) declined to participate, 183 (39%) had an exclusion criterion and 169 (26%) agreed to randomisation. Discussion Due to safety considerations for home-exercise less than half of patients treated by specialist heart failure services were eligible for the study. Many patients had co-morbidities preventing exercise and others had concerns about undertaking an exercise programme.