4,415 research outputs found

    Ustilaginae of Iowa

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    Mycelium located in the tissues of the host, annual or perennial, spores produced from the mycelium at definite points on lines, stems or flowers, gelatinous at first, later pulverulent, in one species a hard, dark mass, smooth, echinulate or reticulated

    Characterizations of Morse quasi-geodesics via superlinear divergence and sublinear contraction

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    We introduce and begin a systematic study of sublinearly contracting projections. We give two characterizations of Morse quasi-geodesics in an arbitrary geodesic metric space. One is that they are sublinearly contracting; the other is that they have completely superlinear divergence. We give a further characterization of sublinearly contracting projections in terms of projections of geodesic segments.Comment: 24 pages, 5 figures. v2: 22 pages, 5 figures. Correction in proof of Thm 7.1. Proof of Prop 4.2 revised for improved clarity. Other minor changes per referee comments. To appear in Documenta Mathematic

    Negative curvature in graphical small cancellation groups

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    We use the interplay between combinatorial and coarse geometric versions of negative curvature to investigate the geometry of infinitely presented graphical Gr′(1/6)Gr'(1/6) small cancellation groups. In particular, we characterize their 'contracting geodesics', which should be thought of as the geodesics that behave hyperbolically. We show that every degree of contraction can be achieved by a geodesic in a finitely generated group. We construct the first example of a finitely generated group GG containing an element gg that is strongly contracting with respect to one finite generating set of GG and not strongly contracting with respect to another. In the case of classical C′(1/6)C'(1/6) small cancellation groups we give complete characterizations of geodesics that are Morse and that are strongly contracting. We show that many graphical Gr′(1/6)Gr'(1/6) small cancellation groups contain strongly contracting elements and, in particular, are growth tight. We construct uncountably many quasi-isometry classes of finitely generated, torsion-free groups in which every maximal cyclic subgroup is hyperbolically embedded. These are the first examples of this kind that are not subgroups of hyperbolic groups. In the course of our analysis we show that if the defining graph of a graphical Gr′(1/6)Gr'(1/6) small cancellation group has finite components, then the elements of the group have translation lengths that are rational and bounded away from zero.Comment: 40 pages, 14 figures, v2: improved introduction, updated statement of Theorem 4.4, v3: new title (previously: "Contracting geodesics in infinitely presented graphical small cancellation groups"), minor changes, to appear in Groups, Geometry, and Dynamic

    Medicine in China, Old and New.

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    Disposition of precipitation: Supply and Demand for Water Use by New Tree Plantations

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    As the greatest rainwater users among all vegetative land covers, tree plantations have been employed strategically to mitigate salinity and water-logging problems. However, large-scale commercial tree plantations in high rainfall areas reduce fresh water inflows to river systems supporting downstream communities, agricultural industries and wetland environmental assets. A bio-economic model was used to estimate economic demand for water by future upstream plantations in a sub-catchment (the 2.8 million ha Macquarie valley in NSW) of the Murray-Darling Basin, Australia. Given four tree-product values, impacts were simulated under two settings: without and with the requirement that permanent water entitlements be purchased from downstream entitlement holders before establishing a tree plantation. Without this requirement, gains in economic surplus from expanding tree plantations exceeded economic losses by downstream irrigators, and stock and domestic water users, but resulted in reductions of up to 154 GL (gigalitres) in annual flows to wetland environments. With this requirement, smaller gains in upstream economic surplus, added to downstream gains, could total $330 million while preserving environmental flows. Extending downstream water markets to new upstream tree plantations, to equilibrate marginal values across water uses, helps ensure water entitlements are not diminished without compensation. Outcomes include better economic-efficiency, social-equity and environmental-sustainability.Environmental Economics and Policy, forest, environmental services, catchment, water sources, interception, entitlement, supply, demand, market, economic surplus, evapo-transpiration, urban water, irrigation, wetlands.,

    House Directory, Kennebunk Village, 1933

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    A local directory of the individuals living at each street and house number in Kennebunk Village in 1933. A timeline of important dates in the history of the village are included as headers and footers on each page, 1603-1930. Also includes advertisements for area businesses
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