Douleur abdominale de la fosse iliaque droite chez un homme de 53 ans

Service d’imagerie médicale, hôpital d’instruction des Armées-Bégin, 69, avenue de Paris, 94163 Saint-Mandé cedex
Feuillets de Radiologie 09/2007; 47(4):286-290. DOI: 10.1016/S0181-9801(07)91905-3
67 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: The modern glaciers of the tropical Andes are a small remnant of the ice that occupied the mountain chain during past glacial periods. Estimates of local Last Glacial Maximum (LGM) snowline depression range from low (e.g., 200–300 m in the Junin region, Peru), through intermediate (600 m at Laguna Kollpa Kkota in Bolivia), to high (e.g., 1100–1350 m in the Cordillera Oriental, Peru). Although a considerable body of work on paleosnowlines exists for the tropical Andes, absolute dating is lacking for most sites. Moraines that have been reliably dated to ∼21 cal kyr BP have been identified at few locations in the tropical Andes. More commonly, but still rarely, moraines can be bracketed between about 10 14C kyr (∼11.5 cal kyr BP) and 30 14C kyr BP. Typically, only minimum-limiting ages for glacial retreat are available. Cosmogenic dating of erratics on moraines may be able to provide absolute dating with sufficient accuracy to identify deposits of the local LGM. Ongoing work using cosmogenic 10Be and 26Al in Peru and Bolivia suggests that the local LGM may have occurred prior to 21 cal kyr BP.
    Quaternary International 09/2005; 138:145-167. DOI:10.1016/j.quaint.2005.02.011 · 2.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Emplacement of glacial moraines normally results in obliteration of any older moraines deposited by less extensive glacial advances, a process we call “obliterative overlap.” A probability analysis of the likely impact of obliterative overlap on the completeness of the glacial record assumes that moraines were deposited at various distances from their glacial source areas randomly over time. Assuming randomness and obliterative overlap, after 10 glacial episodes, the most likely number of surviving moraines is only three. The record of the Pleistocene is in agreement with the probability analysis: the 10 glaciations during the past 0.9 m.y. inferred from the deep-sea record resulted in moraine sequences in which only two or three different-aged moraine belts can generally be distinguished.
    Geology 01/1984; 12(6). DOI:10.1130/0091-7613(1984)12<327:POMSIA>2.0.CO;2 · 4.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last glacial stage, from before 25,000 to 15,000 calibrated years before the present (cal yr B.P.), signifying that during the last glacial maximum (LGM), the Altiplano of Bolivia and Peru and much of the Amazon basin were wetter than today. The LGM in this part of the Andes is dated at 21,000 cal yr B.P., approximately coincident with the global LGM. Maximum aridity and lowest lake level occurred in the early and middle Holocene (8000 to 5500 cal yr B.P.) during a time of low summer insolation. Today, rising levels of Lake Titicaca and wet conditions in Amazonia are correlated with anomalously cold sea-surface temperatures in the northern equatorial Atlantic. Likewise, during the deglacial and Holocene periods, there were several millennial-scale wet phases on the Altiplano and in Amazonia that coincided with anomalously cold periods in the equatorial and high-latitude North Atlantic, such as the Younger Dryas.
    Science 02/2001; 291(5504):640-3. DOI:10.1126/science.291.5504.640 · 33.61 Impact Factor
Show more