71 research outputs found

    Manganese–calcium clusters supported by calixarenes

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    The structure of the oxygen-evolving complex of photosystem II, which contains a cubane-like metal-oxo cluster incorporating four manganese (III,IV) cations, along with a calcium cation, has focussed attention on synthetic analogues of this cluster. Despite this activity, there are relatively few structurally characterised coordination clusters with this combination of metal cations. The calixarenes are synthetically versatile and well established cluster-supporting ligands, which to date have not been reported to support a calcium/manganese cluster. Here we report that p-t-butylthiacalix[4]arene supports CaMn2 and Ca2Mn2 clusters, whereas reactions of p-t-butylcalix[4]arene, p-t-butylsulfinylcalix[4]arene, and p-t-butylsulfonylcalix[4]arene, under the same conditions, produced only homometallic manganese complexes

    Investigation of the structure and magnetism in lanthanide ß-triketonate tetranuclear assemblies

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    The preparation of discrete tetranuclear lanthanide/alkali metal (Ae) assemblies bearing a tribenzoylmethane ligand (LH) is discussed. These assemblies have the general formula [Ln(Ae·HOEt)(L)4]2, where Ln3+ = Gd3+, Tb3+, Dy3+, Ho3+ and Ae+ = Na+, K+, Rb+. The coordination geometries of the lanthanide species were analyzed and compared, revealing a trend between an eight-coordinate square antiprism and triangular dodecahedron dependent on the nature of lanthanide, alkali metal, and lattice solvent. The potassium-containing analogs were also analyzed for their magnetic susceptibility

    Thymoglobulin Induction Dosing Strategies in a Low-Risk Kidney Transplant Population: Three or Four Days?

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    The optimal dose and duration of rabbit antithymocyte globulin (rATG) induction has not been defined. Methods. We compared the safety and efficacy of 2 dosing strategies, rATG 1.5 mg/kg for 4 days (n = 59) versus 2 mg/kg for 3 days (n = 59), in a retrospective, cohort study. Results. Two-year rejection-free survival was 95% in each group (P = .983). Renal function and infection rates were similar. The incidence of leucopenia was similar, although the 2 mg/kg group was more likely to be thrombocytopenic on day 2 (4% versus 28%, P = .04). Length of stay tended to be longer for the 1.5 mg/kg group (6.0 ± 3.7 versus 5.1 ± 1.9 days P = .104). A cost savings of $920 per patient for rATG were seen in the 2 mg/kg group (P = .122). Conclusions. Shorter, more intense dosing of rATG is safe and effective. The 3-day dose strategy resulted in a clinically shorter length of stay and may result in cost savings

    West End Walkers 65+: a randomised controlled trial of a primary care-based walking intervention for older adults:study rationale and design

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    <p>Background: In Scotland, older adults are a key target group for physical activity intervention due to the large proportion who are inactive. The health benefits of an active lifestyle are well established but more research is required on the most effective interventions to increase activity in older adults. The 'West End Walkers 65+' randomised controlled trial aims to examine the feasibility of delivering a pedometer-based walking intervention to adults aged ≥65 years through a primary care setting and to determine the efficacy of this pilot. The study rationale, protocol and recruitment process are discussed in this paper.</p> <p>Methods/Design: The intervention consisted of a 12-week pedometer-based graduated walking programme and physical activity consultations. Participants were randomised into an immediate intervention group (immediate group) or a 12-week waiting list control group (delayed group) who then received the intervention. For the pilot element of this study, the primary outcome measure was pedometer step counts. Secondary outcome measures of sedentary time and physical activity (time spent lying/sitting, standing or walking; activPAL™ monitor), mood (Positive and Negative Affect Schedule), functional ability (Perceived Motor-Efficacy Scale for Older Adults), quality of life (Short-Form (36) Health Survey version 2) and loneliness (UCLA Loneliness Scale) were assessed. Focus groups with participants and semi-structured interviews with the research team captured their experiences of the intervention. The feasibility component of this trial examined recruitment via primary care and retention of participants, appropriateness of the intervention for older adults and the delivery of the intervention by a practice nurse.</p> <p>Discussion: West End Walkers 65+ will determine the feasibility and pilot the efficacy of delivering a pedometer-based walking intervention through primary care to Scottish adults aged ≥65 years. The study will also examine the effect of the intervention on the well-being of participants and gain an insight into both participant and research team member experiences of the intervention.</p&gt

    Spatially resolved star formation and inside-out quenching in the TNG50 simulation and 3D-HST observations

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    We compare the star-forming main sequence (SFMS) of galaxies – both integrated and resolved on 1 kpc scales – between the high-resolution TNG50 simulation of IllustrisTNG and observations from the 3D-HST slitless spectroscopic survey at z ∼ 1. Contrasting integrated star formation rates (SFRs), we find that the slope and normalization of the star-forming main sequence in TNG50 are quantitatively consistent with values derived by fitting observations from 3D-HST with the Prospector Bayesian inference framework. The previous offsets of 0.2–1 dex between observed and simulated main-sequence normalizations are resolved when using the updated masses and SFRs from Prospector. The scatter is generically smaller in TNG50 than in 3D-HST for more massive galaxies with M*> 1010 M⊙, by ∼10–40 per cent, after accounting for observational uncertainties. When comparing resolved star formation, we also find good agreement between TNG50 and 3D-HST: average specific star formation rate (sSFR) radial profiles of galaxies at all masses and radii below, on, and above the SFMS are similar in both normalization and shape. Most noteworthy, massive galaxies with M*> 1010.5 M⊙, which have fallen below the SFMS due to ongoing quenching, exhibit a clear central SFR suppression, in both TNG50 and 3D-HST. In contrast, the original Illustris simulation and a variant TNG run without black hole kinetic wind feedback, do not reproduce the central SFR profile suppression seen in data. In TNG, inside-out quenching is due to the supermassive black hole (SMBH) feedback model operating at low accretion rates

    Understanding the multiframe caricature advantage for recognizing facial composites.

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    Eyewitnesses often construct a ‘composite’ face of a person they saw commit a crime, a picture that police use to identify suspects. We described a technique (Frowd et al., 2007, Visual Cognition, 15, 1-31) based on facial caricature to facilitate recognition of these images: correct naming substantially improves when composites are seen with progressive positive caricature, where distinctive information is enhanced, and then with progressive negative caricature, the opposite. Over the course of four experiments, the underpinnings of this mechanism are explored. Positive-caricature levels were found to be largely responsible for improving naming of composites, with some benefit from negative-caricature levels. Also, different frame-presentation orders (forward, reverse, random, repeated) facilitated equivalent naming benefit relative to static composites. Overall, the data indicate that composites are usually constructed as negative caricatures

    Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation

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    We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish species and incorporates major ecological and evolutionary patterns. Covering virtually all freshwater habitats on Earth, this ecoregion map, together with associated species data, is a useful tool for underpinning global and regional conservation planning efforts (particularly to identify outstanding and imperiled freshwater systems); for serving as a logical framework for large-scale conservation strategies; and for providing a global-scale knowledge base for increasing freshwater biogeographic literacy. Preliminary data for fish species compiled by ecoregion reveal some previously unrecognized areas of high biodiversity, highlighting the benefit of looking at the world's freshwaters through a new framework.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Naturales y Muse

    Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation

    Get PDF
    We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish species and incorporates major ecological and evolutionary patterns. Covering virtually all freshwater habitats on Earth, this ecoregion map, together with associated species data, is a useful tool for underpinning global and regional conservation planning efforts (particularly to identify outstanding and imperiled freshwater systems); for serving as a logical framework for large-scale conservation strategies; and for providing a global-scale knowledge base for increasing freshwater biogeographic literacy. Preliminary data for fish species compiled by ecoregion reveal some previously unrecognized areas of high biodiversity, highlighting the benefit of looking at the world's freshwaters through a new framework.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Naturales y Muse
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