1,305 research outputs found

    Equivariant configuration spaces

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    The compression theorem is used to prove results for equivariant configuration spaces that are analogous to the well-known non-equivariant results of May, Milgram and Segal

    James bundles

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    We study cubical sets without degeneracies, which we call {square}-sets. These sets arise naturally in a number of settings and they have a beautiful intrinsic geometry; in particular a {square}-set C has an infinite family of associated {square}-sets Ji(C), for i = 1, 2, ..., which we call James complexes. There are mock bundle projections pi: |Ji(C)| -> |C| (which we call James bundles) defining classes in unstable cohomotopy which generalise the classical James–Hopf invariants of {Omega}(S2). The algebra of these classes mimics the algebra of the cohomotopy of {Omega}(S2) and the reduction to cohomology defines a sequence of natural characteristic classes for a {square}-set. An associated map to BO leads to a generalised cohomology theory with geometric interpretation similar to that for Mahowald orientation

    Spherical alterations of handles: embedding the manifold plus construction

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    A key tool in our earlier work on ends of manifolds high-dimensional manifolds was an ability to embed cobordisms provided by the Quillen Plus Construction into those ends. Here we develop a `spherical modification' trick which provides a constructive approach to obtaining such embeddings. More importantly, this approach allows for more general embedding results. In this paper we develop generalizations of the plus construction and show how the corresponding cobordisms can be embedded in manifolds satisfying appropriate fundamental group properties. Results obtained here play an important role in our ongoing study of noncompact manifolds.Comment: This final version will appear in Algebraic & Geometric Topology. Small corrections, including a fix to the statement of Theorem 5.3. 22 pages, 4 figure

    TB29: Soil-Water, Chemical and Physical Characteristics of Eight Soil Series in Maine

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    Eight soil series (Adams, Berkshire, Buxton, Colbath, Creasey, Hartland, Peru, Winooski) were sampled, each at five locations. The soil was sampled and analyzed on a horizon basis. Characteristics measured were organic carbon, moisture retention, water movement, particle size distribution, volume of coarse fragments, bulk density, soil reaction, exchangeable bases and exchangeable acidity. These data are important in the classification and interpretation of the soil resources of Maine.https://digitalcommons.library.umaine.edu/aes_techbulletin/1168/thumbnail.jp

    TB46: Chemical and Physical Properties of the Allagash, Hermon, Howland, and Marlow Soil Mapping Units

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    The soils presented in this report were sampled at varying locations in Washington, Hancock, Aroostook and Piscataquis counties. This study was undertaken to ascertain the characteristics of the four mapping units so that their classification and interpretation as to use could be more sharply defined.https://digitalcommons.library.umaine.edu/aes_techbulletin/1141/thumbnail.jp

    All two dimensional links are null homotopic

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    We show that any number of disjointly embedded 2-spheres in 4-space can be pulled apart by a link homotopy, ie, by a motion in which the 2-spheres stay disjoint but are allowed to self-intersect.Comment: 18 pages. Published copy, also available at http://www.maths.warwick.ac.uk/gt/GTVol3/paper10.abs.htm

    TB34: Chemical and Physical Properties of the Charlton, Sutton, Paxton, and Woodbridge Soil Mapping Units

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    Charlton, Sutton, Paxton and Woodbridge soil series were each sampled at five locations. Chemical and physical properties evaluated included particle size distribution, soil reaction, moisture retention, bulk density, coarse fragment volume, exchangeable bases and acidity, saturated hydraulic conductivity, organic carbon and percolation. Properties were evaluated on a horizonal basis whenever possible. Sampling depth was to 40 inches. The samples represent a range of characteristics within each soil series. Each site is not to be considered modal for the particular soil series but was considered to within the range of characteristics of the series at the time of sampling.https://digitalcommons.library.umaine.edu/aes_techbulletin/1151/thumbnail.jp

    TB108: Chemical and Physical Properties of the Becket, Colton, Finch, Lyman, Masardis, Naumburg, and Skerry Soil Mapping Units

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    Soil morphology and soil characterization studies were done on seven soil mapping units in Maine. Soil profiles were selected, described and sampled jointly by soil scientists from the Soil Conservation Service, USDA and the Maine Agricultural Experiment Station. Chemical and physical measurements of each soil mapping unit were made in the laboratory. Soil profile description and the laboratory determinations are presented for each sample site.https://digitalcommons.library.umaine.edu/aes_techbulletin/1092/thumbnail.jp

    A novel non-Fermi-liquid state in the iron-pnictide FeCrAs

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    We report transport and thermodynamic properties of stoichiometric single crystals of the hexagonal iron-pnictide FeCrAs. The in-plane resistivity shows an unusual "non-metallic" dependence on temperature T, rising continuously with decreasing T from ~ 800 K to below 100 mK. The c-axis resistivity is similar, except for a sharp drop upon entry into an antiferromagnetic state at T_N 125 K. Below 10 K the resistivity follows a non-Fermi-liquid power law, rho(T) = rho_0 - AT^x with x<1, while the specific heat shows Fermi liquid behaviour with a large Sommerfeld coefficient, gamma ~ 30 mJ/mol K^2. The high temperature properties are reminiscent of those of the parent compounds of the new layered iron-pnictide superconductors, however the T -> 0 properties suggest a new class of non-Fermi liquid.Comment: 6 pages, 4 figure
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