417 research outputs found

    Introduction to Library Trends 37 (3) Winter 1989: Contemporary Technology in Libraries

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    État rĂ©sumĂ© des acquisitions rĂ©centes sur le Quaternaire chilien

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    Warriors Into Workers: The Civil War and the Formation of Urban-Industrial Society in a Northern City

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    Basic training: The army and the rise of industrial America A truism about wars is that they profoundly change the societies and individuals engaged in them. That is, at least in part, the implication of the phrase the crucible of war. One would think therefore that a familiar...

    Volcanisme, tectonique et réseau hydrographique sur le piémont andin du désert du nord du Chili

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    À partir d'une photographie aĂ©rienne verticale, remarquable par les anomalies qu'elle fait apparaĂźtre dans le tracĂ© du rĂ©seau hydrographique, on peut retracer les principales Ă©tapes de l'Ă©volution du piĂ©mont andin dans le dĂ©sert du Nord du Chili pendant le CĂ©nozoĂŻque supĂ©rieur : 1) puissante accumulation volcano-dĂ©tritique au MiocĂšne infĂ©rieur et moyen, consĂ©quence du soulĂšvement des Andes Ă  la fin de l'OligocĂšne; 2) glaciplanation au MiocĂšne supĂ©rieur; 3) incision des cours d'eau, perturbĂ©e par des mouvements tectoniques importants au PliocĂšne; 4) changements climatiques, caractĂ©risĂ©s par des attĂ©nuations passagĂšres de l'ariditĂ©, Ă  l'origine de diffĂ©rentes gĂ©nĂ©rations de dĂ©pĂŽts dĂ©tritiques au PliocĂšne et au Quaternaire.From a vertical aerial photograph, noteworthy for anomalies which characterize the hydrographic network of the depicted area, are deduced the main stages of the Andean piedmont evolution in the desert of northernmost Chile during the Upper Cenozoic: 1) as a consequence of the uplift of the Andes at the end of the OligocĂšne, thick accumulation of continental sediments and ignimbritic lava flows during the Lower and Middle Miocene; 2) development of a planation surface of pediment type in the Late Miocene; 3) channel incision, disturbed by important tectonic movements in the Pliocene; 4) climatic changes, marked by increased precipitation, generating several generations of clastic deposits in the Pliocene and the Quaternary.Una fotografia aĂ©rea vertical, notable por las anomalias que aparecen en Ia red hidrografica, permite aclarar las principales etapas de la evolucion del pedemonte andino del Norte Grande chileno durante el Cenozoico superior: 1) potente acumulacion volecanica y detritica en el Mioceno inferior y medio, como consecuencia del solevantamiento de los Andes a fines del Oligoceno; 2) pediplanacion en el Mioceno superior; 3) encajonamiento de los cursos de agua, perturbado por importantes movimientos tectĂŽnicos en el Plioceno; 4) cambios climaticos, caracterizados por una atenuacion de la aridez, que producen varias generaciones de depositos detriticos en el Plioceno y el Cuaternario

    Bou Grara (mer de)

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    La mer de Bou Grara, qui couvre une superficie d’environ 450 km2 est situĂ©e dans le Sud tunisien, Ă  proximitĂ© de l’üle de Jerba qu’elle sĂ©pare du continent. Elle communique avec le golfe de GabĂšs par deux passages. Le premier, au nord-est, est celui d’El Kantara qui est large d’environ 6 km et profond de moins de 2 m. Dans l’antiquitĂ©, il a Ă©tĂ© barrĂ© par une chaussĂ©e romaine et, par la suite, des caravanes l’ont franchi Ă  guĂ© en suivant le trik el jemel. L’autre passage, au nord-ouest, corres..

    Biomechanical Tolerance of Whole Lumbar Spines in Straightened Posture Subjected to Axial Acceleration

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    Quantification of biomechanical tolerance is necessary for injury prediction and protection of vehicular occupants. This study experimentally quantified lumbar spine axial tolerance during accelerative environments simulating a variety of military and civilian scenarios. Intact human lumbar spines (T12‐L5) were dynamically loaded using a custom‐built drop tower. Twenty‐three specimens were tested at sub‐failure and failure levels consisting of peak axial forces between 2.6 and 7.9 kN and corresponding peak accelerations between 7 and 57 g. Military aircraft ejection and helicopter crashes fall within these high axial acceleration ranges. Testing was stopped following injury detection. Both peak force and acceleration were significant (p \u3c 0.0001) injury predictors. Injury probability curves using parametric survival analysis were created for peak acceleration and peak force. Fifty‐percent probability of injury (95%CI) for force and acceleration were 4.5 (3.9–5.2 kN), and 16 (13–19 g). A majority of injuries affected the L1 spinal level. Peak axial forces and accelerations were greater for specimens that sustained multiple injuries or injuries at L2–L5 spinal levels. In general, force‐based tolerance was consistent with previous shorter‐segment lumbar spine testing (3–5 vertebrae), although studies incorporating isolated vertebral bodies reported higher tolerance attributable to a different injury mechanism involving structural failure of the cortical shell. This study identified novel outcomes with regard to injury patterns, wherein more violent exposures produced more injuries in the caudal lumbar spine. This caudal migration was likely attributable to increased injury tolerance at lower lumbar spinal levels and a faster inertial mass recruitment process for high rate load application. Published 2017. This article is a U.S. Government work and is in the public domain in the USA

    Bou Grara (mer de)

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    La mer de Bou Grara, qui couvre une superficie d’environ 450 km2 est situĂ©e dans le Sud tunisien, Ă  proximitĂ© de l’üle de Jerba qu’elle sĂ©pare du continent. Elle communique avec le golfe de GabĂšs par deux passages. Le premier, au nord-est, est celui d’El Kantara qui est large d’environ 6 km et profond de moins de 2 m. Dans l’antiquitĂ©, il a Ă©tĂ© barrĂ© par une chaussĂ©e romaine et, par la suite, des caravanes l’ont franchi Ă  guĂ© en suivant le trik el jemel. L’autre passage, au nord-ouest, corres..
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