9,084 research outputs found

    The Insects of Treeholes of Northern Indiana With Special Reference to \u3ci\u3eMegaselia Scalaris\u3c/i\u3e (Diptera: Phoridae) and \u3ci\u3eSpilomyia Longicornis\u3c/i\u3e (Diptera: Syrphidae)

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    The aquatic insect community of treeholes in northern Indiana was surveyed from 1983-1986. Twenty-three species, representing three orders and nine families, were found. Megaselia scalaris (Diptera: Phoridae) was collected on several occasions from rotholes, the first member of this family from treeholes. Examination of puparia of Spilomyia longicornis (Diptera: Syrphidae) indicated that the larva of this species has been previously described, but incorrectly associated with the genus Xylata

    Chuck for delicate drills

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    Development of oil film technique to couple power between drive spindle and drill chuck for delicate drilling operations is discussed. Oil film permits application of sufficient pressure, but stops rotating when drill jams. Illustration of equipment is provided

    Constraining the quintessence equation of state with SnIa data and CMB peaks

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    Quintessence has been introduced as an alternative to the cosmological constant scenario to account for the current acceleration of the universe. This new dark energy component allows values of the equation of state parameter wQ01w_{Q}^0\geq-1, and in principle measurements of cosmological distances to Type Ia supernovae can be used to distinguish between these two types of models. Assuming a flat universe, we use the supernovae data and measurements of the position of the acoustic peaks in the Cosmic Microwave Background (CMB) spectra to constrain a rather general class of Quintessence potentials, including inverse power law models and recently proposed Supergravity inspired potentials. In particular we use a likelihood analysis, marginalizing over the dark energy density ΩQ\Omega_{Q}, the physical baryon density Ωbh2\Omega_{b}h^2 and the scalar spectral index nn, to constrain the slopes of our Quintessence potential. Considering only the first Doppler peak the best fit in our range of models gives wQ00.8w_{Q}^0\sim-0.8. However, including the SnIa data and the three peaks, we find an upper limit on the present value of the equation of state parameter, 1wQ00.93-1\leq w_{Q}^0\leq-0.93 at 2σ2\sigma, a result that appears to rule out a class of recently proposed potentials.Comment: Accepted for pubblication in PRD, 7 pages, 6 figures. New revised analysi

    Fanny Copeland and the geographical imagination

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    Raised in Scotland, married and divorced in the English south, an adopted Slovene, Fanny Copeland (1872 – 1970) occupied the intersection of a number of complex spatial and temporal conjunctures. A Slavophile, she played a part in the formation of what subsequently became the Kingdom of Yugoslavia that emerged from the First World War. Living in Ljubljana, she facilitated the first ‘foreign visit’ (in 1932) of the newly formed Le Play Society (a precursor of the Institute of British Geographers) and guided its studies of Solčava (a then ‘remote’ Alpine valley system) which, led by Dudley Stamp and commended by Halford Mackinder, were subsequently hailed as a model for regional studies elsewhere. Arrested by the Gestapo and interned in Italy during the Second World War, she eventually returned to a socialist Yugoslavia, a celebrated figure. An accomplished musician, linguist, and mountaineer, she became an authority on (and populist for) the Julian Alps and was instrumental in the establishment of the Triglav National Park. Copeland’s role as participant observer (and protagonist) enriches our understanding of the particularities of her time and place and illuminates some inter-war relationships within G/geography, inside and outside the academy, suggesting their relative autonomy in the production of geographical knowledge

    Superhorizon curvaton amplitude in inflation and pre-big bang cosmology

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    We follow the evolution of the curvaton on superhorizon scales and check that the spectral tilt of the curvaton perturbations is unchanged as the curvaton becomes non-relativistic. Both inflation and pre-big bang cosmology can be treated since the curvaton mechanism within the two scenarios works the same way. We also discuss the amplitude of the density perturbations, which leads to some interesting constrains on the pre-big bang scenario. It is shown that within a SL(3,R) non-linear sigma model one of the three axions has the right coupling to the dilaton and moduli to yield a flat spectrum with a high string scale, if a quadratic non-perturbative potential is generated and an intermediate string phase lasts long enough.Comment: 15 pages, LaTeX. Discussion and references adde

    String mediated phase transitions

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    It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed

    New type scalar fields for cosmic acceleration

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    We present a model where a non-conventional scalar field may act like dark energy leading to cosmic acceleration. The latter is driven by an appropriate field configuration, which result in an effective cosmological constant. The potential role of such a scalar in the cosmological constant problem is also discussed.Comment: 6 page

    String Dilaton Fluid Cosmology

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    We investigate (n+1)(n+1)-dimensional string-dilaton cosmology with effective dilaton potential in presence of perfect-fluid matter.We get exact solutions parametrized by the constant \gam of the state equation p=(\gam-1)\rho, the spatial dimension number nn, the bulk of matter, and the spatial curvature constant kk. Several interesting cosmological behaviours are selected. Finally we discuss the recovering of ordinary Einstein gravity starting from string dominated regime and a sort of asymptotic freedom due to string effective coupling.Comment: 16 pages, Latex, submitted to Int. Jou. Mod. Phys.

    Governing in the Shadow of Intergovernmental Hierarchy: Delegation Failure and Executive Empowerment in the European Union

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Perspectives on European Politics and Society on [date of publication], available online: http://wwww.tandfonline.com/[Article DOI]
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