26,261 research outputs found

    Reply to the comment by Jacobs and Thorpe

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    Reply to a comment on "Infinite-Cluster geometry in central-force networks", PRL 78 (1997), 1480. A discussion about the order of the rigidity percolation transition.Comment: 1 page revTe

    Effect of an alternate winglet on the pressure and spanwise load distributions of a first generation jet transport wing

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    Pressure and spanwise load distributions on a first-generation jet transport semispan model at subsonic speeds are presented. The wind tunnel data were measured for the wing with and without an alternate winglet. The results show that the winglet affected outboard wing pressure distributions and increased the spanwise loads near the tip

    Conodontes et Sédimentologie des couches de passage du Givetien au Frasnien dans le Nord du Tafilalt et dans le Ma’der (Maroc Présaharien)

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    Stratigraphically important conodonts relevant to the Givetian-Frasnian boundary are listed from one section in the Tafilalt area and from threein the Ma'der area. The conodont succession from the Middle Polygnathus varcus Subzone and extending into the Middle Polygnathus asymmetricus Zone is described. The corresponding goniatite sequence ranges from the last occurrence of Maenioceras terebratum into beds containing Manticoceras and Beloceras kayseri. The sedimentology of the beds sampled for conodonts at the Tafilalt section and at two of the Ma'der sections is discussed. The conodont Ancyrodella binodosa is fully described;other relevant taxa are briefly discussed

    Effect of winglets on a first-generation jet transport wing. 1: Longitudinal aerodynamic characteristics of a semispan model at subsonic speeds

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    The effects of winglets and a simple wing-tip extension on the aerodynamic forces and moments and the flow-field cross flow velocity vectors behind the wing tip of a first generation jet transport wing were investigated in the Langley 8-foot transonic pressure tunnel using a semi-span model. The test was conducted at Mach numbers of 0.30, 0.70, 0.75, 0.78, and 0.80. At a Mach number of 0.30, the configurations were tested with combinations of leading- and trailing-edge flaps

    Coarsening Dynamics of Granular Heaplets in Tapped Granular Layers

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    A semi-continuum model is introduced to study the dynamics of the formation of granular heaplets in tapped granular layers. By taking into account the energy dissipation of collisions and screening effects due to avalanches, this model is able to reproduce qualitatively the pattern of these heaplets. Our simulations show that the granular heaplets are characterised by an effective surface tension which depends on the magnitude of the tapping intensity. Also, we observe that there is a coarsening effect in that the average size of the heaplets, V grows as the number of taps k increases. The growth law at intermediate times can be fitted by a scaling function V ~ k^z but the range of validity of the power law is limited by size effects. The growth exponent z appears to diverge as the tapping intensity is increased.Comment: 4 pages, 4 figure

    Effect of Winglets on a First-Generation Jet Transport Wing. 2: Pressure and Spanwise Load Distributions for a Semispan Model at High Subsonic Speeds

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    Pressure and spanwise load distributions on a first-generation jet transport semispan model at high subsonic speeds are presented for the basic wing and for configurations with an upper winglet only, upper and lower winglets, and a simple wing-tip extension. Selected data are discussed to show the general trends and effects of the various configurations

    A Monte Carlo Method for Modeling Thermal Damping: Beyond the Brownian-Motion Master Equation

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    The "standard" Brownian motion master equation, used to describe thermal damping, is not completely positive, and does not admit a Monte Carlo method, important in numerical simulations. To eliminate both these problems one must add a term that generates additional position diffusion. He we show that one can obtain a completely positive simple quantum Brownian motion, efficiently solvable, without any extra diffusion. This is achieved by using a stochastic Schroedinger equation (SSE), closely analogous to Langevin's equation, that has no equivalent Markovian master equation. Considering a specific example, we show that this SSE is sensitive to nonlinearities in situations in which the master equation is not, and may therefore be a better model of damping for nonlinear systems.Comment: 6 pages, revtex4. v2: numerical results for a nonlinear syste

    Entropic particle transport: higher order corrections to the Fick-Jacobs diffusion equation

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    Transport of point-size Brownian particles under the influence of a constant and uniform force field through a three-dimensional channel with smoothly varying periodic cross-section is investigated. Here, we employ an asymptotic analysis in the ratio between the difference of the widest and the most narrow constriction divided through the period length of the channel geometry. We demonstrate that the leading order term is equivalent to the Fick-Jacobs approximation. By use of the higher order corrections to the probability density we derive an expression for the spatially dependent diffusion coefficient D(x) which substitutes the constant diffusion coefficient present in the common Fick-Jacobs equation. In addition, we show that in the diffusion dominated regime the average transport velocity is obtained as the product of the zeroth-order Fick-Jacobs result and the expectation value of the spatially dependent diffusion coefficient . The analytic findings are corroborated with the precise numerical results of a finite element calculation of the Smoluchowski diffusive particle dynamics occurring in a reflection symmetric sinusoidal-shaped channel.Comment: 9 pages, 3 figure

    Production of human recombinant proapolipoprotein A-I in Escherichia coli: purification and biochemical characterization

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    A human liver cDNA library was used to isolate a clone coding for apolipoprotein A-I (Apo A-I). The clone carries the sequence for the prepeptide (18 amino acids), the propeptide (6 amino acids), and the mature protein (243 amino acids). A coding cassette for the proapo A-I molecule was reconstructed by fusing synthetic sequences, chosen to optimize expression and specifying the amino-terminal methionine and amino acids -6 to +14, to a large fragment of the cDNA coding for amino acids 15-243. The module was expressed in pOTS-Nco, an Escherichia coli expression vector carrying the regulatable X P^ promoter, leading to the production of proapolipoprotein A-I at up to 10% of total soluble proteins. The recombinant polypeptide was purified and characterized in terms of apparent molecular mass, isoelectric point, and by both chemical and enzymatic peptide mapping. In addition, it was assayed in vitro for the stimulation of the enzyme lecithin: cholesterol acyltransferase. The data show for the first time that proapo A-I can be produced efficiently in E. coli as a stable and undegraded protein having physical and functional properties indistinguishable from those of the natural product

    Application of risk-based, adaptive pathways to climate adaptation planning for public conservation areas in NSW, Australia

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    © 2019 by the authors. Globally, areas of high-quality wildlife habitat of significant environmental value are at risk of permanent damage from climate change. These areas represent social-ecological systems that will require increasing management intervention to maintain their biological and socio-cultural values. Managers of protected areas have begun to recognize the inevitability of ecosystem change and the need to embrace dynamic approaches to intervention. However, significant uncertainty remains about the onset and severity of some impacts, which makes planning difficult. For Indigenous communities, there are intrinsic links between cultural heritage and the conservation of place and biodiversity that need to be better integrated in protected area planning and management. In New SouthWales, Australia, management of public conservation reserves and national parks is the responsibility of a State government agency, the National Parks andWildlife Service (NPWS). This paper describes the outcomes of a participatory planning process with NPWS staff to, firstly, identify the options available, the available 'tool kit', to manage biodiversity and cultural heritage in protected areas; secondly, explore how the selection of management actions from the 'tool kit' is associated with the level of climate risk to biodiversity or cultural heritage assets; and thirdly, to understand how the form of individual management actions might adapt to changes in climate risk. Combining these three elements into a series of risk-based, adaptive pathways for conservation of biodiversity and cultural heritage is a novel approach that is currently supporting place-based planning for public conservation areas. Incorporation of the trade-offs and synergies in seeking to effectively manage these discrete but related types of values and the implications for conservation practice are discussed
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