226 research outputs found

    A framework for the probabilistic analysis of meteotsunamis

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    This paper is not subject to U.S. copyright. The definitive version was published in Natural Hazards 74 (2014): 123-142, doi:10.1007/s11069-014-1294-1.A probabilistic technique is developed to assess the hazard from meteotsunamis. Meteotsunamis are unusual sea-level events, generated when the speed of an atmospheric pressure or wind disturbance is comparable to the phase speed of long waves in the ocean. A general aggregation equation is proposed for the probabilistic analysis, based on previous frameworks established for both tsunamis and storm surges, incorporating different sources and source parameters of meteotsunamis. Parameterization of atmospheric disturbances and numerical modeling is performed for the computation of maximum meteotsunami wave amplitudes near the coast. A historical record of pressure disturbances is used to establish a continuous analytic distribution of each parameter as well as the overall Poisson rate of occurrence. A demonstration study is presented for the northeast U.S. in which only isolated atmospheric pressure disturbances from squall lines and derechos are considered. For this study, Automated Surface Observing System stations are used to determine the historical parameters of squall lines from 2000 to 2013. The probabilistic equations are implemented using a Monte Carlo scheme, where a synthetic catalog of squall lines is compiled by sampling the parameter distributions. For each entry in the catalog, ocean wave amplitudes are computed using a numerical hydrodynamic model. Aggregation of the results from the Monte Carlo scheme results in a meteotsunami hazard curve that plots the annualized rate of exceedance with respect to maximum event amplitude for a particular location along the coast. Results from using multiple synthetic catalogs, resampled from the parent parameter distributions, yield mean and quantile hazard curves. Further refinements and improvements for probabilistic analysis of meteotsunamis are discussed

    DRIFT: Deep Reinforcement Learning for Intelligent Floating Platforms Trajectories

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    This investigation introduces a novel deep reinforcement learning-based suite to control floating platforms in both simulated and real-world environments. Floating platforms serve as versatile test-beds to emulate microgravity environments on Earth. Our approach addresses the system and environmental uncertainties in controlling such platforms by training policies capable of precise maneuvers amid dynamic and unpredictable conditions. Leveraging state-of-the-art deep reinforcement learning techniques, our suite achieves robustness, adaptability, and good transferability from simulation to reality. Our Deep Reinforcement Learning (DRL) framework provides advantages such as fast training times, large-scale testing capabilities, rich visualization options, and ROS bindings for integration with real-world robotic systems. Beyond policy development, our suite provides a comprehensive platform for researchers, offering open-access at https://github.com/elharirymatteo/RANS/tree/ICRA24

    A Poincare-Covariant Parton Cascade Model for Ultrarelativistic Heavy-Ion Reactions

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    We present a new cascade-type microscopic simulation of nucleus-nucleus collisions at RHIC energies. The basic elements are partons (quarks and gluons) moving in 8N-dimensional phase space according to Poincare-covariant dynamics. The parton-parton scattering cross sections used in the model are computed within perturbative QCD in the tree-level approximation. The Q^2 dependence of the structure functions is included by an implementation of the DGLAP mechanism suitable for a cascade, so that the number of partons is not static, but varies in space and time as the collision of two nuclei evolves. The resulting parton distributions are presented, and meaningful comparisons with experimental data are discussed.Comment: 30 pages. 11 figures. Submitted to Phys.Rev.

    Application of dense offshore tsunami observations from Ocean Bottom Pressure Gauges (OBPGs) for tsunami research and early warnings

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    We introduce a new data source of dense deep-ocean tsunami records 7 from Ocean Bottom Pressure Gauges (OBPGs) which are attached to Ocean Bottom 8 Seismometers (OBS) and apply them for far-field and near-field tsunami warnings. 9 Tsunami observations from OBPGs are new sources of deep-ocean tsunami 10 observations which, for the first time, provide dense tsunami data with spacing 11 intervals in the range of 10–50 km. Such dense data are of importance for tsunami 12 research and warnings and are capable of providing new insights into tsunami 13 characteristics. Here, we present a standard procedure for the processing of the 14 OBPG data and extraction of tsunami signals out of these high-frequency data. 15 Then, the procedure is applied to two tsunamis of 15 July 2009 Mw 7.8 Dusky 16 Sound (offshore New Zealand) and 28 October 2012 Mw 7.8 Haida Gwaii (offshore 17 Canada). We successfully extracted 30 and 57 OBPG data for the two aforesaid 18 tsunamis, respectively. Numerical modeling of tsunami was performed for both 19 tsunamis in order to compare the modeling results with observation and to use the 20 modeling results for the calibration of some of the OBPG data. We successfully 21 employed the OBPG data of the 2012 Haida Gwaii tsunami for tsunami forecast by 22 applying a data assimilation technique. Our results, including two case studies, 23 demonstrate the high potential of OBPG data for contribution to tsunami research 24 and warnings. The procedure developed in this study can be readily applied for the 2526 extraction of tsunami signals from OBPG data

    The Imperforate Anus Psychosocial Questionnaire (IAPSQ): Its construction and psychometric properties

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    The origin of the present study was to develop the liaison work between the disciplines of child and adolescent psychiatry and paediatric surgery and nursing, so as to improve the quality of treatment and care of a group of children with imperforate anus (IA) and their families. Imperforate anus is a congenital disease involving a deformity of the anorectum. The early surgery and invasive follow-up treatment associated with IA may affect the child psychosocially, including the child-parent relationship. By developing and testing a questionnaire for children born with anorectal anomalies, a tool for measuring psychosocial functioning can be realized

    Tsunami hazards in the Catalan Coast, a low-intensity seismic activity area

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-017-2918-zThe potential impacts of tsunamis along the Catalan Coast (NW Mediterranean) are analysed using numerical modelling. The region is characterized by moderate to low seismic activity and by moderate- to low-magnitude earthquakes. However, the occurrence of historical strong earthquakes and the location of several active offshore faults in front of the coast suggest that the possibility of an earthquake-triggered tsunami is not negligible although of low probability. Up to five faults have been identified to generate tsunamis, being the highest associated possible seismic magnitudes of up to 7.6. Coastal flooding and port agitation are characterized using the Worst-case Credible Tsunami Scenario Analysis approach. The results show a multiple fault source contribution to tsunami hazard. The shelf dimensions and the existence of submerged canyons control the tsunami propagation. In wide shelves, waves travelling offshore may become trapped by refraction causing the wave energy to reach the coastline at some distance from the origin. The free surface water elevation increases at the head of the canyons due to the sharp depth gradients. The effects of potential tsunamis would be very harmful in low-lying coastal stretches, such as deltas, with a high population concentration, assets and infrastructures. The Ebro delta appears to be the most exposed coast, and about the 20% of the delta surface is prone to flooding due to its extremely low-lying nature. The activity at Barcelona port will be severely affected by inflow backflow current at the entrance of up to 2 m/s.Peer ReviewedPostprint (author's final draft

    Geomorphic and stratigraphic evidence for an unusual tsunami or storm a few centuries ago at Anegada, British Virgin Islands

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    © The Author(s), 2010. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Natural Hazards 63 (2012): 51-84, doi:10.1007/s11069-010-9622-6.Waters from the Atlantic Ocean washed southward across parts of Anegada, east-northeast of Puerto Rico, during a singular event a few centuries ago. The overwash, after crossing a fringing coral reef and 1.5 km of shallow subtidal flats, cut dozens of breaches through sandy beach ridges, deposited a sheet of sand and shell capped with lime mud, and created inland fields of cobbles and boulders. Most of the breaches extend tens to hundreds of meters perpendicular to a 2-km stretch of Anegada’s windward shore. Remnants of the breached ridges stand 3 m above modern sea level, and ridges seaward of the breaches rise 2.2–3.0 m high. The overwash probably exceeded those heights when cutting the breaches by overtopping and incision of the beach ridges. Much of the sand-and-shell sheet contains pink bioclastic sand that resembles, in grain size and composition, the sand of the breached ridges. This sand extends as much as 1.5 km to the south of the breached ridges. It tapers southward from a maximum thickness of 40 cm, decreases in estimated mean grain size from medium sand to very fine sand, and contains mud laminae in the south. The sand-and-shell sheet also contains mollusks—cerithid gastropods and the bivalve Anomalocardia—and angular limestone granules and pebbles. The mollusk shells and the lime-mud cap were probably derived from a marine pond that occupied much of Anegada’s interior at the time of overwash. The boulders and cobbles, nearly all composed of limestone, form fields that extend many tens of meters generally southward from limestone outcrops as much as 0.8 km from the nearest shore. Soon after the inferred overwash, the marine pond was replaced by hypersaline ponds that produce microbial mats and evaporite crusts. This environmental change, which has yet to be reversed, required restriction of a former inlet or inlets, the location of which was probably on the island’s south (lee) side. The inferred overwash may have caused restriction directly by washing sand into former inlets, or indirectly by reducing the tidal prism or supplying sand to post-overwash currents and waves. The overwash happened after A.D. 1650 if coeval with radiocarbon-dated leaves in the mud cap, and it probably happened before human settlement in the last decades of the 1700s. A prior overwash event is implied by an inland set of breaches. Hypothetically, the overwash in 1650–1800 resulted from the Antilles tsunami of 1690, the transatlantic Lisbon tsunami of 1755, a local tsunami not previously documented, or a storm whose effects exceeded those of Hurricane Donna, which was probably at category 3 as its eye passed 15 km to Anegada’s south in 1960.The work was supported in part by the Nuclear Regulatory Commission under its project N6480, a tsunami-hazard assessment for the eastern United States

    Transmission et circulation des savoirs scientifiques et techniques

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    À l’ùre de Facebook et de Twitter, du dĂ©bat sur les fake news, la question de la transmission des savoirs et de la connaissance n’a jamais revĂȘtu autant d’importance. À une Ă©poque oĂč nous sommes submergĂ©s sous le flot des informations, il est de plus en plus difficile d’identifier ce qui constitue un savoir ou un savoir-faire vrai. De rĂ©cents travaux ont rĂ©vĂ©lĂ© l’importance des sciences du vivant, notamment pour l’essor de l’agriculture, mais aussi de la circulation de l’information scientifique et technique, notamment dans la mesure oĂč celle-ci s’accompagne ou mĂȘme, parfois, ouvre la voie Ă  des transferts de technologie. Un axe de recherche que les auteurs ici rĂ©unis explorent Ă  travers une sĂ©rie d’exemples, depuis la fin du xvie siĂšcle jusqu’à nos jours. Le CongrĂšs national des sociĂ©tĂ©s historiques et scientifiques rassemble chaque annĂ©e universitaires, membres de sociĂ©tĂ©s savantes et jeunes chercheurs. Ce recueil est issu de travaux prĂ©sentĂ©s lors du 143e CongrĂšs sur le thĂšme « La transmission des savoirs »

    Ecosystem Resilience and Threshold Response in the GalĂĄpagos Coastal Zone

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    Background: The Intergovernmental Panel on Climate Change (IPCC) provides a conservative estimate on rates of sea-level rise of 3.8 mm yr⁻Âč at the end of the 21st century, which may have a detrimental effect on ecologically important mangrove ecosystems. Understanding factors influencing the long-term resilience of these communities is critical but poorly understood. We investigate ecological resilience in a coastal mangrove community from the GalĂĄpagos Islands over the last 2700 years using three research questions: What are the 'fast and slow' processes operating in the coastal zone? Is there evidence for a threshold response? How can the past inform us about the resilience of the modern system?Methodology/Principal Findings: Palaeoecological methods (AMS radiocarbon dating, stable carbon isotopes (ÎŽ13C)) were used to reconstruct sedimentation rates and ecological change over the past 2,700 years at Diablas lagoon, Isabela, GalĂĄpagos. Bulk geochemical analysis was also used to determine local environmental changes, and salinity was reconstructed using a diatom transfer function. Changes in relative sea level (RSL) were estimated using a glacio-isostatic adjustment model. Non-linear behaviour was observed in the Diablas mangrove ecosystem as it responded to increased salinities following exposure to tidal inundations. A negative feedback was observed which enabled the mangrove canopy to accrete vertically, but disturbances may have opened up the canopy and contributed to an erosion of resilience over time. A combination of drier climatic conditions and a slight fall in RSL then resulted in a threshold response, from a mangrove community to a microbial mat.Conclusions/Significance: Palaeoecological records can provide important information on the nature of non-linear behaviour by identifying thresholds within ecological systems, and in outlining responses to 'fast and slow' environmental change between alternative stable states. This study highlights the need to incorporate a long-term ecological perspective when designing strategies for maximizing coastal resilience.</p
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