9,845 research outputs found

    An Ecological Study of Timberline and Alpine Areas, Mount Lincoln, Park County, Colorado

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    During the short alpine growing season of 1945 the authors had the opportunity of studying conditions and biota on Mount Lincoln, Park County, Colorado, in an attempt to evaluate the ecological conditions and animal communities of the area. Of the large amount of taxonomic and ecological zoology published on the state, most has been in the field of autecology, and, except in the province of aquatic studies, little has appeared bearing on synecological relations, especially among invertebrates. The marked differences between the physiography, climatology, and biology of timberline, alpine, and other stations seemed to offer a field well worthy of investigation. Since the work was done, other factors have been introduced which have greatly altered the nearly primitive conditions encountered at the time of the investigation. One of the areas has been entirely destroyed by the formation of a water storage lake, and others have been affected through heavy summer grazing by bands of sheep. The material published on the Mount Lincoln area is very limited. Cary (1911) was concerned with similar areas in other parts of the state, but apparently he did not work around the mountains at the head of the South Platte. The most detailed paper on the region is that of Patton and his collaborators (1912) which covers the physiography very completely. There are scattered references to the animal life of the vicinity in Coues (1874), Sclater (1912), Warren (1942), and elsewhere. The most complete published reports on the animal life of the region are those of Brewer (1871) and Allen (1872, 1876a, 1876b); the first of Allen\u27s papers is the source of most of Coues\u27 references to the Mount Lincoln avifauna. None of these papers deals with the invertebrates, save for comments by Brewer on the relative abundance of certain orders of insects

    The Condominium and Median-Income Housing

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    Proposed shunt rounding technique for large-scale security constrained loss minimization

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    The official published version can be obtained from the link below - Copyright @ 2010 IEEE.Optimal reactive power flow applications often model large numbers of discrete shunt devices as continuous variables, which are rounded to their nearest discrete value at the final iteration. This can degrade optimality. This paper presents novel methods based on probabilistic and adaptive threshold approaches that can extend existing security constrained optimal reactive power flow methods to effectively solve large-scale network problems involving discrete shunt devices. Loss reduction solutions from the proposed techniques were compared to solutions from the mixed integer nonlinear mathematical programming algorithm (MINLP) using modified IEEE standard networks up to 118 buses. The proposed techniques were also applied to practical large-scale network models of Great Britain. The results show that the proposed techniques can achieve improved loss minimization solutions when compared to the standard rounding method.This work was supported in part by the National Grid and in part by the EPSRC. Paper no. TPWRS-00653-2009

    Matching the High Momentum Modes in a Truncated Determinant Algorithm

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    Within a truncated determinant algorithm, two alternatives are discussed for including systematically the remaining ultraviolet modes. Evidence is presented that these modes are accurately described by an effective action involving only small Wilson loops.Comment: LATTICE98(algorithms) ; typos correcte

    The birth of a politician: Harold Wilson and the bonfires of controls, 1948-9

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    This article uses a detailed examination on the 1948 and 1949 Bonfires of Controls to reassess Harold Wilson's development as a politician and examine the broader relationship between popular politics and economic policy. Whilst acknowledging the continued importance of the latter within Wilson's self-identification as a modernizing 'specialist', it contends that these events are best viewed as representing the birth of a professional politician. It will show that, although economically motivated, there was a marked disparity between each Bonfire's illusion and reality. Far from being entirely rational, each announcement straddled the gap between politics and economics. Within a post-war political landscape that had seen debates about controls become increasingly emotive, Wilson used the Bonfires to seize advantage. As a result, they can be seen to signify the point of his development from a self-identified professional economist to an astute political actor. © The Author [2013]. Published by Oxford University Press. All rights reserved

    Tin Abundances Require that Chassignites Originated from Multiple Magmatic Bodies Distinct from Nakhlites

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    Meteorites from Mars lack field context but chemical and chronologic studies have revealed remarkable links between nakhlites and chassignites. A widely held consensus is that nakhlites and chassignites originated from a large, single differentiated flow or shallow intrusive [1-5]. An Ar-Ar study assumed multiple flows based on resolvable age differences between meteorites [6], but did not address the possibility of differential cooling in a large, shallowly emplaced intrusion [1]. REE abundances in pyroxenes from nakhlites and Chassigny led [7] to argue for derivation of these rocks from distinct magmas. Volatile abundances (F, Cl, OH) in chlorapatites indicated that the entire suite of nakhlites and chassignites experienced hydrothermal interaction with a single fluid supporting a single body origin [4]. The discovery of a new chassignite, NWA 8694, extended the Mg# range from 80-54, providing a closer link to nakhlites but revealed the petrological difficulty of fractionating a single body of liquid to yield a series of olivine cumulates with such a large Mg# range [8]. When mafic magmas are emplaced into the crust, crustal assimilation can impart distinct elemental signatures if the country rock has experienced sedimentary or hydrothermal processing [9]. In this work, we used Sn abundances of nakhlites and chassignites to show that these rocks were crystallized from distinct magma batches, providing vital contextual clues to their origin

    Chalcophile Element Constraints on the Sulfur Content of the Martian Mantle

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    The sulfur content of the Martian mantle is critical to understanding volcanic volatiles supplied to the surface of Mars and possibly climate. In the absence of Martian mantle rocks, sulfur content of the mantle has been inferred from S contents of Martian meteorites or from sedimentary sulfate abundances. Estimates of the sulfur content of the Martian mantle vary from 390-2,000 ppm, all of which are higher than that of the terrestrial mantle (~250 ppm;). Residual sulfide in the Martian mantle controls the distribution of chalcophile elements during partial melting. In this study, we report new analyses of Martian meteorites, and use the incompatible behavior of As, Tl and Pb to infer the sulfide mode of the Martian mantle using a different set of assumptions than those of prior studies

    Direct calculation of interfacial tensions from computer simulation: Results for freely jointed tangent hard sphere chains

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    We develop a methodology for the calculation of surface free energies based on the probability distribution of a wandering interface. Using a simple extension of the NpT sampling, we allow the interface area to randomly probe the available space and evaluate the surface free energy from histogram analysis and the corresponding average. The method is suitable for studying systems with either continuous or discontinuous potentials, as it does not require explicit evaluation of the virial. The proposed algorithm is compared with known results for the surface tension of Lennard--Jones and Square Well fluid, as well as for the interface tension of a bead--spring polymer model and good agreement is found. We also calculate interfacial tensions of freely jointed tangent hard sphere chains on athermal walls for a wide range of chain lengths and densities. The results are compared with three different theoretical approaches, Scaled Particle Theory, the Yu and Wu density functional theory and an analytical approximation based on the latter approach. Whereas SPT only yields qualitative results, the last two approaches are found to yield very good agreement with simulations.Comment: 20 pages, 6 figures, Phys. Rev. E in press
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