Morphological and sedimentary impacts and recovery on a mixed sandy to pebbly seabed exposed to marine aggregate extraction (Eastern English Channel,France)     

Sophie Le Bot  Robert Lafite  Matthieu Fournier  Agnès Baltzer  Michel Desprez 《Estuarine, Coastal and Shelf Science》2010

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Wildfire preparedness,community cohesion and social–ecological systems     

Tim Prior  Christine Eriksen 《Global Environmental Change》2013,23(6):1575-1586

The consequences of wildfires are felt in susceptible communities around the globe on an annual basis. Climate change predictions in places like the south-east of Australia and western United States suggest that wildfires may become more frequent and more intense with global climate change. Compounding this issue is progressive urban development at the peri-urban fringe (wildland–urban interface), where continued infrastructure development and demographic changes are likely to expose more people and property to this potentially disastrous natural hazard. Preparing well in advance of the wildfire season is seen as a fundamental behaviour that can both reduce community wildfire vulnerability and increase hazard resilience – it is an important element of adaptive capacity that allows people to coexist with the hazardous environment in which they live. We use household interviews and surveys to build and test a substantive model that illustrates how social cohesion influences the decision to prepare for wildfire. We demonstrate that social cohesion, particularly community characteristics like ‘sense of community’ and ‘collective problem solving’, are community-based resources that support both the adoption of mechanical preparations, and the development of cognitive abilities and capacities that reduce vulnerability and enhance resilience to wildfire. We use the results of this work to highlight opportunities to transfer techniques and approaches from natural hazards research to climate change adaptation research to explore how the impacts attributed to the social components of social–ecological systems can be mitigated more effectively.  相似文献   

The challenge of dating early pleistocene fossil teeth by the combined uranium series–electron spin resonance method: the Venta Micena palaeontological site (Orce,Spain)     

Mathieu Duval  Christophe Falguères  Jean‐Jacques Bahain  Rainer Grün  Qingfeng Shao  Maxime Aubert  John Hellstrom  Jean‐Michel Dolo  Jordi Agusti  Bienvenido Martínez‐Navarro  Paul Palmqvist  Isidro Toro‐Moyano 《第四纪科学杂志》2011,26(6):603-615

The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix–Baza basin, one of the best documented areas in Europe for Plio‐Pleistocene biostratigraphy. The combination of biochronological and palaeomagnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeomagnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series–electron spin resonance (US‐ESR) dating of Early Pleistocene sites. Although the US‐ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U‐mobilization event that led to some U‐leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured ²³⁰Th/²³⁴U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U‐mobilization processes, to improve the reliability of the combined US‐ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Cryptotephra from the 74 ka BP Toba super-eruption in the Billa Surgam caves,southern India     

Christine Lane  Michael Haslam  Michael Petraglia  Peter Ditchfield  Victoria Smith  Ravi Korisettar 《Quaternary Science Reviews》2011,30(15-16):1819-1824

The ～74 ka BP Youngest Toba Tuff (YTT), from the largest known Quaternary volcanic eruption, has been found for the first time as a non-visible (crypto-) tephra layer within the Billa Surgam caves, southern India. The occurrence of the YTT layer in Charnel House Cave provides the first calendrical age estimate for this much debated Pleistocene faunal sequence and demonstrates the first successful application of cryptotephrochronology within a cave sequence. The YTT layer lies ～50 cm below a major sedimentological change, which is related to global cooling around the MIS 5 to MIS 4 transition. Using this isochronous event layer the Billa Surgam Cave record can be directly correlated with other archaeological sites in peninsular India and palaeoenvironmental archives across southern Asia.  相似文献   

    

Michel Dupuy 《Journal of Geodesy》1952,26(3):345-357

Résumé La simplicité du calcul de la réduction au plan est une des qualités pratiques les plus importantes dans toute projection géodésique. Comme les calculs sont à l'heure actuelle entièrement effectués en coordonnés rectangulaires, la réduction au plan demande à être calculée exclusivement à partir des dits éléments: telle est bien du reste la situation en ce qui concerne la projection de Mercator Transverse, communément employée. Pour la projection conique conforme deLambert, officiellement employée pour la triangulation fran?aise, on obtient une formule commode en introduisant l'aire triangulaire comprise entre le sommet de la projection conique (image du p?le) et les stations AB à relier. Le présent acticle justifie cette formule, décrit son application par la section de Géodésie de l'Institut Géographique National, et spécifie les formules de moyenne à employer: cette note forme un ensemble avec l'article suivant deM. Dufour.

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Summary Simplicity of calculation in the plane is one of the most important characteristics of any surveyor's projection. Since all calculation is today carried out in terms of rectangular coordinates, any reduction to the plane should involve only these coordinates: and this is, in fact, the situation in the commonly employed Transverse Mercator projection. For theLambert Conical orthomorphic projection, officially used for the French triangulation, a convenient formula is obtained in terms of the area of the triangle formed by the two points concerned and the vertex of the projection (which represents the pole in the plane). This paper justifies the use of the formula; describes its application by the Institut Géographique National; and discusses the different mean value formulae which are suited to the various grades of accuracy desired. This paper should be considered together with that ofM. Dufour.

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Zusammenfassung In jeder geod?tischen Projektion besteht das Haupterfordernis für eine praktische Durchführung darin, da? die Berechnung der Reduktionen auf die Ebene m?glichst einfach sei. Da gegenw?rtig alle Rechnungen mit Hilfe von rechtwinkligen Koordinaten durchgeführt werden, mu? die Reduktion auf die Ebene ausschlie?lich von den genannten Elementen ausgehen. So liegen jedenfalls die Dinge bei der gemeinhin verwendeten Transversalen Mercator-Projektion. Für die Lambertsche konforme Kegelprojektion, die amtliche Projektion für das franz?sische Dreiecksnetz, erh?lt man eine zweckdienliche Formel, wenn man die Dreiecksfl?che zwischen dem Scheitelpunkt der Kegelprojektion (Bildpunkt des Poles) und den zu verbindenden Stationen A B benutzt. Der vorliegende Artikel begründet diese Formel, beschreibt ihre Verwendung durch die Geod?tische Abteilung des Franz?sischen Instituts für Geographie (Section de Géodésie de l'Institut Géographique National) und erl?utert die zu verwendenden Mittelwert-Formeln. Der Aufsatz geh?rt mit dem folgenden vonM. Dufour geschriebenen eng zusammen.

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Resumen La sencillez del cálculo de la reducción al plano es una de las condiciones prácticas más importantes en toda proyección geodésica. Como actualmente están efectuados los cálculos en coordenadas rectangulares, la reducción al plano exige ser calculada exclusivamente a partir de dichos elementos; tal es por lo demás la situación en lo que concierne a la proyección deMercator Transverse, comúnmente empleada. Para la proyección cónica conforme deLambert, oficialmente empleada para la triangulación francesa, se obtiene una fórmula cómoda introduciendo el área triangular comprendida entre el vértice de la proyección cónica (imagen del polo) y las estaciones A y B a enlazar. El presente articulo justifica esta fórmula, y describe su aplicación por la Sección de Geodesia del Instituto Geogróafico Nacional.

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Sommario La semplicità del calcolo delle riduzioni al piano è una delle qualià pratiche più importanti in ogni proiezione geodetica. Poichè attualmente tutti i calcoli di una triangolazione vengono effettuati sul piano, in coordinate rettangolari, è essenziale che tali riduzioni possano avvenire facendo ricorso ai soli elementi piani; come accade in particolare per la proiezione trasversa di Mercatore. Per la proiezione conica conforme diLambert, usata ufficialmente uella triangolazione francese, si ottiene una formula comoda per la riduzione alla corda introducendo l'area del triangolo formalo dall' immagine del polo, e dai due punti da collegare. L'articolo giustifica questa formula, ne descrive la sua applicazione da parte della Sezione Geodetica dell' Istituto Geografico Nazionale, e precisa le formule da impiegare. Esso è collegato con l'articolo seguente del sig.Dufour, col quale forma un tutto unico.

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Efficiences Comparees de Filets a Plancton Coniques de Memes Dimensions et de Mailles Differentes. I. Etudes Generales     

Grandperrin  R.; Michel  A. 《ICES Journal of Marine Science》1969,33(1):53-66

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Megaturbidites: A depositional model from the eocene of the SW-Pyrenean Foreland basin,Spain     

Pierre Labaume  Emiliano Mutti  Michel Seguret 《Geo-Marine Letters》1987,7(2):91-101

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Rapport ARN/ADN et evaluation de l'etat nutritionnel et de la croissance des larves de poissons marins: un essai de mise au point experimentale chez la sole (Solea solea L.)     

Bergeron  Jean-Pierre; Boulhic  Michel 《ICES Journal of Marine Science》1994,51(2):181-190

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Prediction of wave height based on half-cycle excursion analysis     

Michel K. Ochi  Michael A. Eckhoff 《Ocean Engineering》1984,11(6):581-591

This paper presents a method to evaluate statistical properties of half-cycle excursions including extreme values. The probability density function for half-cycle excursions for an arbitrarily given wave spectrum is developed based on the Gaussian assumption. The results of numerical computations carried out using wave data obtained during hurricane Camille show that the half-cycle probability density function agrees well with the histogram constructed from the data. The extreme wave height for design consideration computed with risk parameter 0.01 is approximately 20% greater than the observed extreme height.  相似文献   

Variability in oceanographic and ecological processes in the Canadian Arctic Archipelago     

C. Michel  R.G. Ingram  L.R. Harris 《Progress in Oceanography》2006,71(2-4):379

This paper brings together unpublished historical data sets and published literature to review the role of climatic, oceanographic and ecological processes in the marine ecosystem of the eastern Canadian Archipelago. Physical data include characteristics of the water masses, circulation patterns, sea ice conditions, and climatic records from 1950s onward. Biological data include unpublished data sets on nutrients, primary and secondary production, and sedimentation, which were collected during the 1980–1990s in the eastern Canadian Archipelago. These results show high year-to-year variability in nutrient inventories and ratios, the magnitude of the ice algae and phytoplankton bloom, the timing of ice algae sedimentation in the spring, and the composition of the zooplankton community. The significance of this high interannual variability and its effect on pelagic–benthic coupling processes is discussed in the context of climatic and oceanographic forcing, with emphasis on recent (past decade) Arctic changes. An estimate of total primary production in the Archipelago is also presented, along with published production estimates for other Arctic shelves, showing that the Archipelago may support up to 32% of the total primary production of Arctic shelves. The high year-to-year variability in production and carbon transfer pathways (e.g. pelagic versus benthic) in the Archipelago suggest that the system might be resilient to the increased variability in climatic conditions occurring in the past decade. However, this increased variability combined with directional change in climatic and oceanographic conditions might also modify the existing balance of ecological processes. For example, shifts in the timing of events appear to have already occurred in the past decade, with potential cascading effects throughout the ecosystem.  相似文献