Search results for " Collapse"
showing 10 items of 86 documents
Supernova 1987A: a Template to Link Supernovae to their Remnants
2015
The emission of supernova remnants reflects the properties of both the progenitor supernovae and the surrounding environment. The complex morphology of the remnants, however, hampers the disentanglement of the two contributions. Here we aim at identifying the imprint of SN 1987A on the X-ray emission of its remnant and at constraining the structure of the environment surrounding the supernova. We performed high-resolution hydrodynamic simulations describing SN 1987A soon after the core-collapse and the following three-dimensional expansion of its remnant between days 1 and 15000 after the supernova. We demonstrated that the physical model reproducing the main observables of SN 1987A during …
Effect of progressive collapse of central column on the push-down response of two-span beam-column substructures
2021
Abstract In this paper, a simplified model is proposed for hand calculation of the push-down curve of reinforced two-span beam-column substructures with the mid-span column subjected to a vertical load inducing progressive collapse response. The model takes into account the flexural, arch and catenary strength mechanisms and the axial stiffness of RC compressed columns. The model was validated against experimental data available in the literature. The expressions derived, in a closed form, were useful for hand calculation of push-down responses and robustness evaluation of RC framed structures. The derived explicit expressions can be applied in a step-by-step manner for tracing nonlinear be…
X-ray Computed Tomography for Capillary Collapse of Loose Unsaturated Sand
2016
Abstract The collapse of unsaturated soils consists of the reduction in volume upon wetting at constant total stress. Several studies at the macro scale outline the influence of initial void ratio, confining pressure and matric suction on the onset of collapse of standard laboratory specimens. Conversely, few observations at the micro scale are available in the literature, although the influence of the particles arrangement and intergranular bonding has been formerly supposed. The collapse of fine sand derived by a pyroclastic soil of Southern Italy is investigated in this paper at the microscale using the X-ray Computed Tomography. The experimental procedure, formerly tested on similar pyr…
Structural control on the presence and character of calas: Observations from Balearic Islands limestones rock coast macroforms
2013
Calas are characteristic embayed rocky coastline landforms related to steep-sided drowned valleys that were deeply incised during low sea-level stages into carbonate plateaus. This paper studies the factors that control the presence and character of calas in three different islands of the Balearic Archipelago (Mallorca, Menorca and Formentera) by means of Digital Elevation Model (DEM) reconstructions, embayment and catchment morphometric analysis and through the compilation of fault and joint orientations. All islands exhibit emerged carbonate platforms (Upper Miocene in age) characterised by horizontal or very gently-dipping bedding. Two distinct patterns observed at all study sites are th…
Crisis, economic policy and inequality in Spain
2015
Este trabajo analiza el impacto social que tanto el colapso económico como las políticas desplegadas durante la crisis han producido en España. Esta crisis ha puesto de manifiesto la fragilidad del crecimiento económico español. Además, tanto las medidas de austeridad adoptadas a partir de 2010 como las reformas en el mercado de trabajo y el Estado de Bienestar han empeorado las condiciones de vida de la población. La consecuencia de estos años de crisis y política económica es un aumento explosivo del paro, la reducción de los ingresos personales, la intensificación de la desigualdad y el aumento de la pobreza. This paper analyses the social impact of both the economic collapse and policie…
Hydro-mechanical behaviour of a sandy silt from a river embankment
2020
The paper presents the results of an experimental campaign aimed at characterizing the hydro-mechanical behaviour of a sandy silt from a river embankment. Due to continuous river level fluctuations and changing climatic and environmental conditions, flood embankment materials experience frequent variations in degree of saturation and suction values. Such variations strongly impact the earthwork performance both in terms of seepage and stability conditions. For these reasons, a detailed characterization of the material behaviour in unsaturated conditions was carried out. Experiments were designed in order to highlight the response of the involved soil in terms of changes in matric suction an…
Synsedimentary collapse on a carbonate platform margin (lower Barremian, southern Vercors, SE France)
2004
International audience; A large area of synsedimentary collapse covering about 25 km2 has been identified within Lower Barremian carbonate platform strata of the Southern Vercors (Vocontian Basin, SE France). New observations of the prograding/aggrading strata of the Cirque d'Archiane and the Glandasse Plateau reveal the presence of a disturbed zone, showing tilted and imbricated blocks as well as slump features. Measurements and analysis on these synsedimentary distorted strata suggest that they compose a slide which slipped on the Barremian slope. The occurence of two coarse bioclastic grainstone beds on the eastern side of the Archiane Valley, in a distal hemipelagic context, suggests th…
Physiologie und Pathophysiologie des respiratorischen Systems
2006
Positive pressure ventilation in children is associated with problems similar to those in the adults: development of atelectasis and barotrauma. During anesthesia atelectasis develop in up to 90% of patients, requiring the use of higher inspiratory pressure to recruit the collapsed lung regions. Especially in the preterm, newborn and younger infants, prolonged ventilation disturbs the anatomical structure of the soft and vulnerable immature airways and their subsequent growth and development, leading to tracheomegaly, tracheal collapse, and bronchopulmonary dysplasia and predisposing to bronchial obstruction. On the basis of pathophysiologic knowledge and studies of ventilation in children,…
Kümmell's Disease: Clarifying the Mechanisms and Patients' Inclusion Criteria.
2014
The three major causes of vertebral body collapse include infection, malignant neoplasia, and trauma and it may be difficult to distinguish between them, particularly in the presence of severe osteoporosis. In 1891, however, Dr Hermann Kümmell, further added another possibility of vertebral body crush; the delayed posttraumatic collapse. As originally described, this rare clinical entity includes patients, who after a trivial trauma and an asymptomatic clinical course they develop a progressive vertebral body collapse and a painful kyphosis. Although more than a century has passed from its initial description, only few cases have been reported in the literature, whereas the main pathologic …
Asymptomatic Bone Cement Pulmonary Embolism after Vertebroplasty: Case Report and Literature Review
2013
Introduction. Acrylic cement pulmonary embolism is a potentially serious complication following vertebroplasty. Case Report. A 70-year-old male patient was treated with percutaneous vertebroplasty for osteoporotic nontraumatic vertebral collapse of L5-S1. Asymptomatic pulmonary cement embolism was detected on routine postoperative chest radiogram and the patient was treated with enoxaparin, amoxicillin, and dexamethasone. At the followup CT scan no further migration of any cement material was reported; and the course was uneventful. Discussion. The frequency of local leakage of bone cement is relatively high (about 80–90%), moreover, the rate of cement leakage into the perivertebral veins (…