10,158 research outputs found

    Some physical and economic aspects of water use in the wear basin

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    The thesis analyses the changing pattern of water utilication within the wear catchment over the historic period. First the evolution and present characteristics of the surface water system are examined. River discharge over the period May 1965 – September 1967 was measured by the erection of a gauging station at the Abbey weir. Durham, and rainfall records, kept over the same period were applied to the computed results. Secondly the use of these ater resources is considered, before 1830 water power was widespread and used as a prine mover in many aspects of a productive economy. Water supply was organised on a local and family basis, and although the drainage functions of atercoures were ubiquitous, the low density of population had little effect on the quality of river water. After 1830 water power declined and water supply began to be organised on a community basis, with abstraction from one plant on a local stream an the distribution extended until the unit of supply became a statutory aea and contained many communities. The drainage function of watercourses became more important with the development of urban communities, and the extension of shaft mining for coal and lead. Since 1945 water power has almost disappeared. Water supply is being though of in regional terms, and the role of the wear has been reduced. The drainage function of atercourses remains important, although effluents must now maintain a high degree of purity consequent on the increasing use of watercourses as an arenity. This has always been of some importance’s, with angling remembered since the days of the “Lambton Worn” and pleasure boasting since the late seventeenth century

    Linking dwarf galaxies to halo building blocks with the most metal-poor star in Sculptor

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    Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. Based on the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum cast some doubt on this conclusion. However, verification of the iron-deficiency and measurements of additional elements, such as the alpha-element Mg, are mandatory for demonstrating that the same type of stars produced the metals found in dwarf galaxies and the Galactic halo. Only then can dwarf galaxy stars be conclusively linked to early stellar halo assembly. Here we report high-resolution spectroscopic abundances for 11 elements in S1020549, confirming the iron abundance of less than 1/4000th that of the Sun, and showing that the overall abundance pattern mirrors that seen in low-metallicity halo stars, including the alpha-elements. Such chemical similarity indicates that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs, and suggests that the early chemical enrichment of all galaxies may be nearly identical.Comment: 16 pages, including 2 figures. Accepted for publication in Nature. It is embargoed for discussion in the press until formal publication in Natur

    Brood Season Habitat Selection by Montezuma Quail in Southeastern Arizona

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    Habitat conditions during brood season can affect Montezuma quail (Cyrtonyx montezumae) population levels in Arizona, and land use practices can affect these habitat conditions. General habitat affinities of Montezuma quail are known, however, information on specific habitat selection patterns is limited. We investigated seasonal habitat selection by Montezuma quail in the foothills of the Huachuca and Santa Rita mountains in southeastern Arizona. We used pointing dogs to locate quail during brood seasons (Aug–Oct) of 1998 and 1999. We measured habitat components at 60 flush sites and 60 associated (100 m) random plots. Compared to random plots, quail used areas with higher grass and forb species richness, and more trees (P \u3c 0.10). Low level (\u3c= 50 cm) visual obstruction, usually associated with bunchgrass cover, was greater (P \u3c 0.10) at flush sites than at random plots. Optimum brood season habitat for Montezuma quail should contain \u3e= 6 species of forbs/0.01 ha, tree canopy cover between 10 and 50%, and grass canopy cover between 50 and 85% with a minimum average height of 25cm. Maintaining these habitat characteristics could minimize negative impacts of land-use practices on Montezuma quail

    Numerical modeling of quasiplanar giant water waves

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    In this work we present a further analytical development and a numerical implementation of the recently suggested theoretical model for highly nonlinear potential long-crested water waves, where weak three-dimensional effects are included as small corrections to exact two-dimensional equations written in the conformal variables [V.P. Ruban, Phys. Rev. E 71, 055303(R) (2005)]. Numerical experiments based on this theory describe the spontaneous formation of a single weakly three-dimensional large-amplitude wave (alternatively called freak, killer, rogue or giant wave) on the deep water.Comment: revtex4, 8 pages, 7 figure

    Reka bentuk untuk kestabilan struktur

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    Buku ini mengandungi beberapa bab iaitu kandungan: kata penghantar, prakata, tatatanda, bab 1 tabii ketakstabilan, pengenalan, bab 2 ketakstabilan sesatah bagi tiang, pengenalan, lengkokan euler keseluruhan, tiang berhujung-cemat sempurna – pendekatan klasik, lengkungan awal dalam tiang berhujung-cemat tiang dikenakan beban sisi-tiang rasuk, tiang berbeban sipi, tegasan di dalam tiang bergeometri taksempurna, tegasan baki, tiang terpencil sebenar dan kod rekabentuk, keadaan hujung tiang, fungsi kestabilan, anggota prisma tanpa huyung, anggota prisma berhuyung, anggota tak-prisma, perembat, bibliografi, bab 3 lengkokan sisi bagi rasuk, pengenalan, piuhan keratan-i, lengkokan rasuk, runtuhan rasuk ‘nyata’, penggunaan teori lengkokan sisi terhadap rekabentuk rasuk, kesan dari momen tak-segaya, kegunaan faktor–m di dalam rekabentuk, kesan tahap pengenaan beban melintang, kesan dari keadaan sokong hujung, kelakuan rasuk selanjar, halangan sisi berkesan, rasuk jalur, kesan lengkokan tempatan, rasuk selain dari keratan-i seragam berbebibir-sama, bibliografi, bab 4 beban genting anjal bagi kerangka satah, pengenalan, kelakuan kerangka dan ketakstabilan kerangka, beban genting anjal bagi kerangka kerja tanpa huyung: teknik corak momen, beban genting anjal bagi kerangka kerja tanpa huyung: teknik santaian winter, beban genting anjal bagi kerangka kerja tanpa huyung: teknik kerangka gantian bolton, beban genting anjal bagi kerangka kerja tanpa huyung: portal terembat, pendekatan ‘agihan kekukuhan’ wood, beban genting anjal bagi kerangka kerja huyung: fungsi tiada-ricih n dan o, beban genting anjal bagi kerangka kerja huyung: teknik corak momen, beban genting anjal bagi kerangka kerja huyung: teknik santaian winter, beban genting anjal bagi kerangka kerja huyung: kaedah wood, beban genting anjal bagi kerangka kerja huyung: kaedah horne, beban genting anjal dan rekabentuk kerangka, bibliografi, lampiran serta indeks

    Staying out of range: increasing attacking distance in fencing

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    To avoid being hit, fencers typically adopt an out of range position, which was hypothesized to be governed by body- and action-scaled affordances. This theory was measured in elite and national level junior (u20) fencers. Associations between “reachability” of lunging and step-lunging attacks, was assessed against height, arm-span, leg-span, body mass and lower-body power, and then compared across level. Reachability was determined as the distance covered by fencers during these attacks and was reported as actual and estimated distances. Elite fencers are better at estimating their lunging and step-lunge distance compared to national ranked junior fencers (-0.9 vs. 7.3 % and 5.4 vs. 10.9 % respectively). Surprisingly, elite fencers’ actual and estimated distances for these was less than the junior fencers’ (222.6 vs. 251.5 cm and 299.3 vs. 360.2 cm respectively), and significantly so in the former. Finally only arm (r = .81) and leg span (r = .71) were significantly correlated to estimated lunging distance and this was only in elite fencers. Findings suggest that better fencers can accurately predict their attack range and that reachability appears to be positively influenced by arm and leg-span; these may feed in to talent identification. Given that distances were less in elite fencers, findings suggests that timing and distance estimation are key skills to master, and that the mastery of these in offensive actions can mitigate to a large extent, the physical benefits of an opponent’s greater height

    Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies

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    We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effective yields of the less luminous half of our galaxy sample do not exceed 0.02 Z_sun, indicating that gas outflow is important in the chemical evolution of the less luminous galaxies. We surmise that the ratio of the importance of gas infall to gas outflow increases with galaxy luminosity. Strong correlations of average [Fe/H] and metallicity spread with luminosity support this hypothesis.Comment: 17 pages, 5 figures; accepted for publication in ApJ; minor corrections in v3; corrected typographical errors in Tables 1 and 3 in v
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