691 research outputs found

    Active, Small-Scale, Periglacial Features on the South Coast of Newfoundland

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    Small-scale, patterned ground is currently forming on the south coast of Newfoundland. Small, sorted circles and stripes form in the vicinity of the coast under the influence of marine climate with numerous, short duration, freeze-thaw cycles, high humidity, abundant rainfall and a thin snow cover throughout the winter, inland, no more than 15 to 25 km from the coast, the marine influence has decreased sufficiently that the patterned ground is no longer forming.On trouve prĂ©sentement des sols structurĂ©s Ă  petite Ă©chelle en formation sur la cĂŽte sud de Terre-Neuve. De petits cercles et des traĂźnĂ©es minĂ©rales se dĂ©veloppent prĂšs de la cĂŽte sous l'influence du climat maritime, caractĂ©risĂ© par plusieurs cycles de gel-dĂ©gel, une humiditĂ© relative Ă©levĂ©e, des pluies abondantes et une mince couverture de neige, pendant l'hiver. À l'intĂ©rieur des terres, Ă  15-25 km de la cĂŽte tout au plus, l'influence maritime est suffisamment amoindrie pour qu'il n'y ait plus formation de sols structurĂ©s

    First Assessment of Mountains on Northwestern Ellesmere Island, Nunavut, as Potential Astronomical Observing Sites

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    Ellesmere Island, at the most northerly tip of Canada, possesses the highest mountain peaks within 10 degrees of the pole. The highest is 2616 m, with many summits over 1000 m, high enough to place them above a stable low-elevation thermal inversion that persists through winter darkness. Our group has studied four mountains along the northwestern coast which have the additional benefit of smooth onshore airflow from the ice-locked Arctic Ocean. We deployed small robotic site testing stations at three sites, the highest of which is over 1600 m and within 8 degrees of the pole. Basic weather and sky clarity data for over three years beginning in 2006 are presented here, and compared with available nearby sea-level data and one manned mid-elevation site. Our results point to coastal mountain sites experiencing good weather: low median wind speed, high clear-sky fraction and the expectation of excellent seeing. Some practical aspects of access to these remote locations and operation and maintenance of equipment there are also discussed.Comment: 21 pages, 2 tables, 15 figures; accepted for publication in PAS

    A comparison of value-added models for school accountability

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    School accountability systems increasingly hold schools to account for their performances using value-added models purporting to measure the effects of schools on student learning. The most common approach is to fit a linear regression of student current achievement on student prior achievement, where the school effects are the school means of the predicted residuals. In the literature, further adjustments are usually made for student sociodemographics and sometimes school composition and 'non-malleable' characteristics. However, accountability systems typically make fewer adjustments: for transparency to end users, because data is unavailable or of insufficient quality, or for ideological reasons. There is therefore considerable interest in understanding the extent to which simpler models give similar school effects to more theoretically justified but complex models. We explore these issues via a case study and empirical analysis of England's 'Progress 8' secondary school accountability system

    Raised Shoreline Phenomena and Postglacial Emergence in South-Central Newfoundland

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    Two types of raised marine shoreline features occur in the Burin-Hermitage area of southern Newfoundland marine benches cut in bedrock, and terraces and beaches developed in unconsolidated materials. Most of the benches are older than Late Wisconsinan, and a horizontal rock shoreline at 4.5 ± 1.5 m, which occurs throughout the region, was probably formed in the last interglacial period. Raised deltas and coastal outwash deposits graded to former sea level positions, which define the Late Wisconsinan marine limit across the northern part of the study area, are correlated with terraces and raised beaches further south on the Burin Peninsula. The elevations of these features are used to define the regional pattern of postglacial emergence. More than 30 m of emergence has occurred in the northwest, but the extreme southern part of the region is undergoing submergence.Dans la rĂ©gion de Burin-Hermitage, au sud de Terre-Neuve, on retrouve deux types de lignes de rivage marines soulevĂ©es: des plates-formes marines entaillĂ©es dans la roche en place ainsi que des terrasses et des plages dĂ©veloppĂ©es dans des matĂ©riaux meubles. La plupart des plates-formes datent d'avant le Wisconsinien infĂ©rieur. Une ligne de rivage rocheuse horizontale situĂ©e Ă  4,5 ± 1,5 m, qu'on retrouve Ă  travers la rĂ©gion, fut probablement formĂ©e au cours du dernier interglaciaire. Des deltas soulevĂ©s et des Ă©pandages fluvioglaciaires cĂŽtiers, associĂ©s Ă  des plans d'eau marins qui marquent la limite marine du Wisconsinien infĂ©rieur dans la partie nord de la zone d'Ă©tude, sont mis en relation avec des terrasses et des plages soulevĂ©es existant plus au sud dans la pĂ©ninsule de Burin. L'altitude de ces formes sert Ă  Ă©tablir le mode rĂ©gional d'Ă©mersion post-glaciaire. Il s'est produit une emersion de plus de 30 m dans le nord-ouest, alors que l'extrĂȘme-sud de la rĂ©gion est en phase de submersion

    A review and evaluation of secondary school accountability in England: Statistical strengths, weaknesses, and challenges for 'Progress 8' raised by Covid-19

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    School performance measures are published annually in England to hold schools to account and to support parental school choice. This article reviews and evaluates the ‘Progress 8’ secondary school accountability system for state-funded schools. We assess the statistical strengths and weaknesses of Progress 8 relating to: choice of pupil outcome attainment measure; potential adjustments for pupil input attainment and background characteristics; decisions around which schools and pupils are excluded from the measure; presentation of Progress 8 to users, choice of statistical model, and calculation of statistical uncertainty; and issues related to the volatility of school performance over time, including scope for reporting multi-year averages. We then discuss challenges for Progress 8 raised by the COVID-19 pandemic. Six simple recommendations follow to improve Progress 8 and school accountability in England. Context and implication Rationale for this study This study fulfils a need for a comprehensive statistical evaluation of the Progress 8 school accountability system in England, which has been in place since 2016. Why the new findings matter A review of Progress 8 is an important contribution as decisions on its calculation and presentation have important consequences for schools and pupils. Implications for educational researchers and policy makers Our findings on the statistical strengths and weaknesses of Progress 8 and the resulting recommendations made for improvements to the measure and school accountability have clear implications for informing policy makers in the educational system. This includes wider lessons extending beyond Progress 8 to other performance metrics and to other school systems internationally where similar issues apply. Additionally, the review highlights key concerns that the public and school practitioners may like to consider when drawing upon Progress 8 to make decisions around school choice and in assessing how well a school is performing

    Pathotypic diversity of Hyaloperonospora brassicae collected from Brassica oleracea

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    Downy mildew caused by Hyaloperonospora brassicae is an economically destructive disease of brassica crops in many growing regions throughout the world. Specialised pathogenicity of downy mildews from different Brassica species and closely related ornamental or wild relatives has been described from host range studies. Pathotypic variation amongst Hyaloperonospora brassicae isolates from Brassica oleracea has also been described; however, a standard set of B. oleracea lines that could enable reproducible classification of H. brassicae pathotypes was poorly developed. For this purpose, we examined the use of eight genetically refined host lines derived from our previous collaborative work on downy mildew resistance as a differential set to characterise pathotypes in the European population of H. brassicae. Interaction phenotypes for each combination of isolate and host line were assessed following drop inoculation of cotyledons and a spectrum of seven phenotypes was observed based on the level of sporulation on cotyledons and visible host responses. Two host lines were resistant or moderately resistant to the entire collection of isolates, and another was universally susceptible. Five lines showed differential responses to the H. brassicae isolates. A minimum of six pathotypes and five major effect resistance genes are proposed to explain all of the observed interaction phenotypes. The B. oleracea lines from this study can be useful for monitoring pathotype frequencies in H. brassicae populations in the same or other vegetable growing regions, and to assess the potential durability of disease control from different combinations of the predicted downy mildew resistance genes
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