574 research outputs found
Large Experimental Segmental Bone Defects Treated By Bone Transportation With Monolateral External Distractors
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.
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
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 ). 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 TĂscar: su significado en la terminaciĂłn sudoeste del arco PrebĂ©tico
10 páginas, 11 figuras, 1 tabla.[EN] The TĂscar 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
TĂscar 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 TĂscar, localizada en la terminaciĂłn SO del arco PrebĂ©tico, es un rasgo importante
dentro de la Zona Externa BĂ©tica, donde ha contribuido a la separaciĂłn de dos dominios geolĂłgicos
diferentes. Esta falla afectĂł a la cobertera mesozoica y terciaria despegada del basamento paleozoico
y se formĂł 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
permitiĂł la continuaciĂłn 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 TĂscar 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 AndalucĂa RNM 163 y 217.Peer reviewe
Anomalous Commutator Algebra for Conformal Quantum Mechanics
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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