574 research outputs found

    Large Experimental Segmental Bone Defects Treated By Bone Transportation With Monolateral External Distractors

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    Monolateral frames were applied to five dogs and ten lambs for treatment of large segmental bone defects (LSBD) surgically induced in one of their femoral diaphyses. Reconstruction was attempted by bone transport, as developed by Ilizarov. Monolateral frames were used to minimize the draw-backs of Ilizarov's circular device. Radiographic, computed tomographic, and histologic studies were performed. The skin and soft tissues were not a major obstacle for the longitudinal migration of the screws during bone transport. Four months after the operations, healing and remodeling of the bone defect was always satisfactory. Histologically, the repair of the lengthened segment followed an intramembranous ossification pattern in its central areas and in the periphery as well. At the end of the experiment, the new induced bone had a virtually normal diaphyseal bone appearance. Bone transport for the treatment of experimental LSBD can be completed in monolateral frames

    Climatic vulnerabilities and ecological preferences of soil invertebrates across biomes.

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    Unlike plants and vertebrates, the ecological preferences, and potential vulnerabilities of soil invertebrates to environmental change, remain poorly understood in terrestrial ecosystems globally. We conducted a cross-biome survey including 83 locations across six continents to advance our understanding of the ecological preferences and vulnerabilities of the diversity of dominant and functionally important soil invertebrate taxa, including nematodes, arachnids and rotifers. The diversity of invertebrates was analyzed through amplicon sequencing. Vegetation and climate drove the diversity and dominant taxa of soil invertebrates. Our results suggest that declines in forest cover and plant diversity, and reductions in plant production associated with increases in aridity, can result in reductions of the diversity of soil invertebrates in a drier and more managed world. We further developed global atlases of the diversity of these important soil invertebrates, which were cross-validated using an independent database. Our study advances the current knowledge of the ecological preferences and vulnerabilities of the diversity and presence of functionally important soil invertebrates in soils from across the globe. This information is fundamental for improving and prioritizing conservation efforts of soil genetic resources and management policies

    Black Hole Thermodynamics from Near-Horizon Conformal Quantum Mechanics

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    The thermodynamics of black holes is shown to be directly induced by their near-horizon conformal invariance. This behavior is exhibited using a scalar field as a probe of the black hole gravitational background, for a general class of metrics in D spacetime dimensions (with D≥4D \geq 4). The ensuing analysis is based on conformal quantum mechanics, within a hierarchical near-horizon expansion. In particular, the leading conformal behavior provides the correct quantum statistical properties for the Bekenstein-Hawking entropy, with the near-horizon physics governing the thermodynamic properties from the outset. Most importantly: (i) this treatment reveals the emergence of holographic properties; (ii) the conformal coupling parameter is shown to be related to the Hawking temperature; and (iii) Schwarzschild-like coordinates, despite their ``coordinate singularity,''can be used self-consistently to describe the thermodynamics of black holes.Comment: 16 pages. Sections 2 and 3 and sections 4 and 5 of version 1 were merged and reduced; a few typos were corrected. The original central results and equations remain unchange

    La falla de Tíscar: su significado en la terminación sudoeste del arco Prebético

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    10 páginas, 11 figuras, 1 tabla.[EN] The Tíscar fault, located towards the SW end of the Prebetic arc, is an important feature within the Betic External Zone which contributed to the separation of two different geologic domains. This fault affected the Mesozoic and Tertiary cover detached from the Palaeozoic basement and was developed as consequence of the blockage of the thrust sheets of the western border of the arc, because they could not advance farther over the basement situated progressively in a shallower position. Hence, this fault encouraged the continuation of the NW displacements in the western block, formed by Subbetic olistostromic masses and part of the Prebetic situated in the end of the arc. Although the Tíscar fault has been defined by one main line, there are in fact other parallel faults that form a broad fault zone. Its displacement began during the late Miocene and continued till Pliocene, within a near N-S compressive setting with a perpendicular extension.[ES] La falla de Tíscar, localizada en la terminación SO del arco Prebético, es un rasgo importante dentro de la Zona Externa Bética, donde ha contribuido a la separación de dos dominios geológicos diferentes. Esta falla afectó a la cobertera mesozoica y terciaria despegada del basamento paleozoico y se formó como consecuencia de que los cabalgamientos del borde occidental del arco quedaron bloqueados al no poder avanzar más sobre el basamento cada vez menos profundo. Entonces la falla permitió la continuación de los movimientos hacia el NO de su bloque occidental formado por materiales del Subbético, dispuesto en masas olistostrómicas, e incluso parte del propio Prebético del extremo del arco. Aunque la falla de Tíscar se ha definido por su traza principal, existen otras paralelas que en conjunto forman una amplia zona. Sus movimientos iniciados en el Mioceno superior continuaron hasta el Plioceno, en un contexto de compresión N-S y extensión perpendicular.Este estudio se ha financiado a través de los proyectos BTE2001-5230-E, CGL200401636/BTE, CGL2004-03333/ BTE, CGL2005-01520/BTE y BTE2001-5230-E y los grupos de la Junta de Andalucía RNM 163 y 217.Peer reviewe

    Anomalous Commutator Algebra for Conformal Quantum Mechanics

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    The structure of the commutator algebra for conformal quantum mechanics is considered. Specifically, it is shown that the emergence of a dimensional scale by renormalization implies the existence of an anomaly or quantum-mechanical symmetry breaking, which is explicitly displayed at the level of the generators of the SO(2,1) conformal group. Correspondingly, the associated breakdown of the conservation of the dilation and special conformal charges is derived.Comment: 23 pages. A few typos corrected in the final version (which agrees with the published Phys. Rev. D article
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