835 research outputs found

    Properties of the Milky Way stellar disks in the direction of the Draco dSph galaxy

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    We present the first results of a study where we determine the metallicity distribution function in the Galactic disks as a function of height above the Galactic plane. Observations in the Stromgren photometric system enables us to identify the dwarf stars and derive metallicities for them. The resulting metallicity distribution functions at 0.5 and 2.0 kpc above the Galactic plane are significantly broader and more metal-rich than is anticipated from standard models such as the Besancon model. Our results can be explained by invoking a smaller scale height and larger local normalisation for the thick disk than is commonly used in the models. These results are compatible with recent determinations of the thick disk scale height based e.g. on SDSS data. The age of the stellar populations as a function of height above the Galactic plane is also investigated by studying the turn-off colour and metallicity. We tentatively find that at 2.0 kpc above the Galactic plane there exist an intermediate age population.Comment: 6 pages, 4 figures, IAU symposium 25

    Effects of present-day deglaciation in Iceland on mantle melt production rates

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    Ongoing deglaciation in Iceland not only causes uplift at the surface but also increases magma production at depth due to decompression of the mantle. Here we study glacially induced decompression melting using 3‐D models of glacial isostatic adjustment in Iceland since 1890. We find that the mean glacially induced pressure rate of change in the mantle increases melt production rates by 100–135%, or an additional 0.21–0.23 km3 of magma per year beneath Iceland. Approximately 50% of this melt is produced underneath central Iceland. The greatest volumetric increase is found directly beneath Iceland's largest ice cap, Vatnajökull, colocated with the most productive volcanoes. Our models of the effect of deglaciation on mantle melting predict a significantly larger volumetric response than previous models which only considered the effect of deglaciation of Vatnajökull, and only mantle melting directly below Vatnajökull. Although the ongoing deglaciation significantly increases the melt production rate, the increase in melt supply rate at the base of the lithosphere is delayed and depends on the melt ascent velocity through the mantle. Assuming that 25% of the melt reaches the surface, the upper limit on our deglaciation‐induced melt estimates for central Iceland would be equivalent to an eruption the size of the 2010 Eyjafjallajökull summit eruption every seventh year

    Adrenocorticotrophic hormone lowers serum Lp(a) and LDL cholesterol concentrations in hemodialysis patients

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    Adrenocorticotrophic hormone lowers serum Lp(a) and LDL cholesterol concentrations in hemodialysis patients. Previously, we have shown that short-term administration of adrenocorticotrophic hormone (ACTH) results in reduced concentrations of apolipoprotein B-containing lipoproteins, including lipoprotein(a), and reduced activities of hepatic lipase. These effects were observed in steroid-treated patients suffering from iatrogenic ACTH deficiency and in healthy individuals. The direct nature of the influence of ACTH on hepatic lipoprotein metabolism was confirmed by in vitro experiments. The aim of the present investigation was to study the effects of ACTH treatment on uremic patients, who exhibit disturbed lipoprotein pattern due to the slow removal of triglyceride-rich lipoproteins and who probably are ACTH resistant. Eight patients on chronic hemodialysis were studied. After one intramuscular injection of Synacthen Depot (a synthetic ACTH1–24 preparation from Ciba Geigy AG, Basel, Switzerland) 1 mg, the only change noted was a significant reduction of 26% in median lipoprotein(a) concentration. After five injections, a further decrease (65%) was found in the lipoprotein(a) concentration. Also, reductions in median concentrations of total cholesterol, low density lipoprotein cholesterol and apolipoprotein B were observed. The magnitude of these changes was 15 to 30%. In contrast to previously studied groups, no changes were observed regarding triglyceride metabolism. Significantly increased median concentration of apolipoprotein CIII was found. However, the excess apolipoprotein CIII was confined to the fraction that was not associated with apolipoprotein B. Thus, administration of ACTH to uremic patients improved their atherogenic lipoprotein profile, a fact that may have future therapeutic implications. In comparison to previously studied groups, the uremic patients responded rather slowly and not at all regarding triglyceride metabolism

    An evaluation of key working for families of children and young people with special educational needs and disabilities

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    Key working is a way of supporting children and young people with special educational needs and disabilities (SEND) and their families, and is highly regarded by families and practitioners. However, there is a lack of up-to-date research exploring key working in the current context of policy reforms in England. This article reports an evaluation of key working in four sites in England, with a particular focus on the SEND policy reforms. Key working resulted in a number of positive outcomes for children and young people, families and services, including helping services to meet the requirements of the SEND reforms. Challenging aspects included managing transitions and the relationship between key working practitioner and family, but successful strategies were identified. Key working supports the implementation of specific aspects of the English SEND reforms along with more general cultural change in services to align with families’ needs and well-established aspects of good practice

    Glacio-isostatic deformation around the Vatnajokull ice cap, Iceland, induced by recent climate warming: GPS observations and finite element modeling

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    Glaciers in Iceland began retreating around 1890, and since then the Vatnajökull ice cap has lost over 400 km3 of ice. The associated unloading of the crust induces a glacio‐isostatic response. From 1996 to 2004 a GPS network was measured around the southern edge of Vatnajökull. These measurements, together with more extended time series at several other GPS sites, indicate vertical velocities around the ice cap ranging from 9 to 25 mm/yr, and horizontal velocities in the range 3 to 4 mm/yr. The vertical velocities have been modeled using the finite element method (FEM) in order to constrain the viscosity structure beneath Vatnajökull. We use an axisymmetric Earth model with an elastic plate over a uniform viscoelastic half‐space. The observations are consistent with predictions based on an Earth model made up of an elastic plate with a thickness of 10–20 km and an underlying viscosity in the range 4–10 × 1018 Pa s. Knowledge of the Earth structure allows us to predict uplift around Vatnajökull in the next decades. According to our estimates of the rheological parameters, and assuming that ice thinning will continue at a similar rate during this century (about 4 km3/year), a minimum uplift of 2.5 meters between 2000 to 2100 is expected near the current ice cap edge. If the thinning rates were to double in response to global warming (about 8 km3/year), then the minimum uplift between 2000 to 2100 near the current ice cap edge is expected to be 3.7 meters
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