286 resultados para Leap year.


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This article reviews the judgments issued by the UK Supreme Court during the first year of its existence (October 2009 - September 2010) and assesses how the modus operandi of the new court differs from that of its predecessor, the Appellate Committee of the House of Lords.

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We dated a continuous, ~22-m long sediment sequence from Lake Challa (Mt. Kilimanjaro area, Kenya/Tanzania) to produce a solid chronological framework for multi-proxy reconstructions of climate and environmental change in equatorial East Africa over the past 25,000 years. The age model is based on a total of 168 AMS 14C dates on bulk-organic matter, combined with a 210Pb chronology for recent sediments and corrected for a variable old-carbon age offset. This offset was estimated by i) pairing bulk-organic 14C dates with either 210Pb-derived time markers or 14C dates on grass charcoal, and ii) wiggle-matching high-density series of bulk-organic 14C dates. Variation in the old-carbon age offset through time is relatively modest, ranging from ~450 yr during glacial and late glacial time to ~200 yr during the early and mid-Holocene, and increasing again to ~250 yr today. The screened and corrected 14C dates were calibrated sequentially, statistically constrained by their stratigraphical order. As a result their constrained calendar-age distributions are much narrower, and the calibrated dates more precise, than if each 14C date had been calibrated on its own. The smooth-spline age-depth model has 95% age uncertainty ranges of ~50–230 yr during the Holocene and ~250–550 yr in the glacial section of the record. The d13C values of paired bulk-organic and grass-charcoal samples, and additional 14C dating on selected turbidite horizons, indicates that the old-carbon age offset in Lake Challa is caused by a variable contribution of old terrestrial organic matter eroded from soils, and controlled mainly by changes in vegetation cover within the crater basin.

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This article presents the findings of a randomized controlled trial evaluation of the effects of a revised version of the volunteer mentoring programme, Time to Read. Participating children received two 30-minute mentoring sessions per week from volunteer mentors who carried out paired reading activities with the children. The current trial involved 512 children aged eight to nine years from 50 primary schools. The programme was found to be effective in improving decoding skills (d=+.15), reading rate (d=+.22) and reading fluency (d=+.14) and there was some evidence of a positive effect in relation to the children’s aspirations for the future (d=+.11). However, no evidence was found of the programme having an effect on reading comprehension or reading confidence and enjoyment of reading. The article concludes by suggesting that mentoring programmes using non-specialist volunteers can be effective in improving foundational reading skills but would appear to be less effective in terms of improving higher-order skills such as comprehension. The article also suggests that such programmes are likely to be most effective if concentrating on core reading activities rather than attempting to address reading outcomes indirectly through improving children’s confidence or wider enjoyment of reading.

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This paper uses data from the 2009 Kids’ Life and Times Survey, involving 3657 children aged 10 or 11 years old in Northern Ireland. The survey indicated high levels of use of Internet applications, including social-networking sites and online games. Using the KIDSCREEN-27 instrument, the data indicate that the use of social-networking sites and online games is related to poorer psychological well-being among girls, but not boys. Boys and girls who experience “cyberbullying” have poorer psychological well-being. This association between psychological well-being and some Internet applications merits more attention in future research and policy development.

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This paper uses data from the 2009 Kids’ Life and Times Survey, involving 3657 children aged 10 or 11 years old in Northern Ireland. The survey indicated high levels of use of Internet applications, including social-networking sites and online games. Using the KIDSCREEN-27 instrument, the data indicate that the use of social-networking sites and online games is related to poorer psychological well-being among girls, but not boys. Boys and girls who experience “cyberbullying” have poorer psychological well-being. This association between psychological well-being and some Internet applications merits more attention in future research and policy development.

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Testate amoebae have been used widely as a proxy of hydrological change in ombrotrophic peatlands, although their response to abiotic controls in other types of mire and fenland palaeo-environments is less well understood. This paper examines the response of testate amoebae to hydroseral and other environmental changes at Mer Bleue Bog, Ontario, Canada, a large ombrotrophic peatland, which evolved from a brackish-water embayment in the early Holocene. Sediments, plant macrofossils and diatoms examined from a 5.99 m core collected from the dome of the bog record six stages of development: i) a quiet, brackish-water riverine phase (prior to ca. 8500 cal BP); ii) a shallow lake (ca. 8500–8200 cal BP); iii) fen (8200–7600 cal BP); iv) transitional mire (7600–6900 cal BP); v) pioneer raised mire (6900–4450 cal BP); and vi) ombrotrophic bog (4450 cal BP-present).

Testate amoebae, notably small (<25 µm diameter) specimens of Centropyxis aculeata type, first appear in low abundances in sediments ascribed to the lacustrine phase. Diatoms from the same horizons record a shallowing in water depth, a decline in salinity and the development of emergent macrophytic vegetation, which may have provided favourable conditions for testate amoeba colonization. The testate amoeba communities of the inferred fen phase are more diverse and include centropyxids, cyclopyxids, Arcellidae and Hyalospheniidae, although the assemblages show some differences to those recently reported in modern European fen environments. The Fen–Bog Transition (FBT) is also dominated by C. aculeata type. The change in testate amoeba communities around this key transition is apparent in the results of Detrended Correspondence Analysis (DCA), and appears to reflect a latent nutrient gradient and a secondary moisture gradient. DCA analyses of plant macrofossil remains around the FBT show a similar trend, although the sensitivity of the two proxies to the inferred environmental changes differs. Comparisons with other regional mid-Holocene peatland records confirm the important influence of reduced effective precipitation on the testate amoeba communities during the initiation and development of Sphagnum-dominated, raised bog communities.

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Gender and body mass index are major factors affecting ability to perform effective cardiopulmonary resuscitation.