50,411 research outputs found

    Many homes for tourism:re-considering spatializations of home and away in tourism mobilities

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    Tourism mobilities have long been spatialized as circular structures emanating from a primary home that is opposed to a space of ‘away’. Increasingly complex personal mobilities and experiences with multiple homes, however, challenge the assumptions on which this spatialization of tourism rests. This article utilizes an analysis of travel memoir narratives of return home and second home mobilities to deconstruct the oppositions within traditional spatializations of tourism, revealing in the process the way in which the everyday and tourism are entangled and interactive. Memoir authors construct complex relationships between spaces and places, wherein second homes can inspire new tourism practices at both unfamiliar locations and primary homes, and returning to previous homes can involve tourism of and at home. A consideration of these relationships reveals the difficulty of labeling mobilities as essentially touristic and suggests possibilities for new spatializations, ontology and methodologies that leave room for many homes for tourism

    The Magnetic Fields of the Universe and Their Origin

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    Recent rotation measure observations of a dozen or so galaxy clusters have revealed a surprisingly large amount of magnetic fields, whose estimated energy and flux are, on average, 1058\sim 10^{58} ergs and 1041\sim 10^{41} G cm2^2, respectively. These quantities are so much larger than any coherent sums of individual galaxies within the cluster that an efficient galactic dynamo is required. We associate these fields with single AGNs within the cluster and therefore with all galaxies during their AGN phase. Only the central, massive black hole (BH) has the necessary binding energy, 1061\sim 10^{61} ergs. Only the accretion disk during the BH formation has the winding number, 1011\sim 10^{11} turns, necessary to make the gain and magnetic flux. We present a model of the BH accretion disk dynamo that might create these magnetic fields, where the helicity of the αΩ\alpha - \Omega dynamo is driven by star-disk collisions. The back reaction of the saturated dynamo forms a force-free field helix that carries the energy and flux of the dynamo and redistributes them within the clusters.Comment: 10 pages, 1 figure (figures.png), invited talk at IAU 19

    Dirac and Weyl Superconductors in Three Dimensions

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    We introduce the concept of 3D Dirac (Weyl) superconductors (SC), which have protected bulk four(two)-fold nodal points and surface Andreev arcs at zero energy. We provide a sufficient criterion for realizing them in centrosymmetric SCs with odd-parity pairing and mirror symmetry, e.g., the nodal phases of Cux_xBi2_2Se3_3. Pairs of Dirac nodes appear in a mirror-invariant plane when the mirror winding number is nontrivial. Breaking mirror symmetry may gap Dirac nodes producing a topological SC. Each Dirac node evolves to a nodal ring when inversion-gauge symmetry is broken. A Dirac node may split into a pair of Weyl nodes, only when time-reversal symmetry is broken.Comment: 5 pages and 2 figure

    \u3ci\u3eTomicus Piniperda\u3c/i\u3e (Coleoptera: Scolytidae) Reproduction and Development in Scots, Jack, Red and Eastern White Pine Under Laboratory Conditions

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    The pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), is an exotic bark beetle in North America that was first found in the Great Lakes region in 1992. We evaluated T. piniperda reproduction and development in one Eurasian pine (Scots pine, Pinus sylvestris L.) and three North American pines (jack pine, P. banksiana Lamb.; red pine, P. resinosa Ait.; and eastern white pine, P. strobus L.) under laboratory conditions. We introduced one pair of adults into individual pine bolts, allowed development, collected brood, and later debarked all bolts and measured galleries. Reproduction and development occurred in all pine species tested. Mean phloem thickness varied significantly among the bolts used to represent the four pine species; it was thickest in red pine (1.3 mm) and thinnest in jack pine (0.6 mm). Linear regression analysis indicated that initial brood production (larval galleries per cm of egg gallery) increased significantly with increasing phloem thickness (r2 = 0.36), using the pooled data set for all four pine species. Using phloem thickness as a covariate, mean initial brood density (larval galleries per cm of gallery) was significantly highest on red pine, intermediate on Scots pine and white pine, and lowest on jack pine. Overall brood survival was highest on Scots pine (86%) and lowest on jack (72%) and white pine (76%); phloem thickness was not a significant covariate in this analysis
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