1,721,033 research outputs found
Environmental magnetic record of the Eocene-Oligocene transition in the CRP-3 drillcore, Victoria Land Basin, Antarctica
No full textEvidence for short polarity intervals within Chrons C13r to C12r (late Eocene to early Oligocene) in high-sedimentation-rate cores from the Ross Sea, Antarctica (abstract of paper presented at AGU Fall Meeting, San Francisco, CA, 10-14 Dec 2001)
No full textGlaciation across the Oligocene-Miocene boundary in southern McMurdo Sound, Antarctica: new chronology from the CIROS-1 drill hole
No full textFew Palaeogene and Neogene sediment cores from the Antarctic continental margin have been dated with sufficient precision to enable establishment of direct linkages between glacial events on the Antarctic continent and marked events in deep-sea [delta]18O records. As a result, much of our knowledge of the gradual, but stepwise, shift from 'greenhouse' climates of the Cretaceous to the 'ice-house' climates of the Quaternary is inferred from well-dated and more continuously deposited deep-sea sediments. In this study, we present new magnetostratigraphic results from the CIROS-1 drill core from McMurdo Sound, Antarctica, along with a reinterpretation of a published diatom biostratigraphic zonation that is constrained by correlation to a high-precision age model from the nearby CRP-2/2A drill core. Our results suggest that most of the upper 350 m of the CIROS-1 drill core represents rapid sediment accumulation during a short time interval spanning the Oligocene-Miocene boundary. Chronostratigraphic control is precise enough to enable correlation of this interval of glacimarine sedimentation with the Mi-1 deep-sea [delta]18O event, which confirms that the Mi-1 event was related to a major expansion of Antarctic ice. A major unconformity at 366 m in the CIROS-1 drill core, which is widely observed in regional seismic reflection studies, represents 9 Myr of missing time. This unconformity can be traced offshore into the Ross Sea using seismic stratigraphy and is interpreted to indicate significant East Antarctic ice sheet development during the Mi-1 glaciation. The stratigraphic expression of this ~400-kyr glacial event is evidently multiphase and complex in the Victoria Land Basin, probably because it was punctuated by higher-frequency orbitally induced glacial oscillations. The presence of Nothofagidites pollen throughout the CIROS-1 drill core and the presence of a Nothofagus (Southern beech) leaf within the early Miocene portion of the core indicate that Antarctic mean summer temperatures did not decrease below 5[deg]C throughout the Mi-1 glaciation. These temperatures are significantly warmer than present-day mean summer temperatures at sea level in McMurdo Sound. The persistence of a Nothofagus forest in coastal southern Victoria Land throughout this time interval suggests that the present state of deep refrigeration was not reached until some time after the Mi-1 glaciatio
Magnetostratigraphy of Oligocene-Miocene glaciomarine strata from the CRP-2/2A core, Victoria Land Basin, Antarctica
No full text
Fatigue Crack Growth Prediction for generalized fiber metal laminates and hybrid materials
No full textThe excellent durability performance of Glare, a thin fiber metal laminate (FML) material system, is now being proven in service. This has motivated work towards the application of FMLs to thicker structures driven by damage tolerance. In order to fully characterize the crack growth life of such materials, models are necessary that can account for the unique aspects of material systems under consideration, including non-uniformity of composition and stress states, and the resulting complex damage state involved in fatigue crack growth. This thesis presents a generalized analytical model for the prediction of fatigue crack and delamination growth in FMLs of arbitrary lay-up, including differing metal alloys, different thickness layers, and different combinations of reinforcing composite layers. Cracks in each layer, and delaminations in each interface, are allowed to grow separately, with the interactions of the damage throughout the laminate taken into account. The model is structured in a modular and iterative fashion. Modules for determining the load redistribution around damage and the strain energy release rate of delamination have been derived and independently validated through comparison to finite element analyses. A series of tests with thick fiber metal laminates of varied construction was carried out to verify the overall crack growth predictions of the model. While some discrepancies between the results and predictions for the most complex laminates suggest that refinement of the delamination strain energy release rate formulation is needed, many of the test results were accurately predicted, demonstrating the suitability of this model for use in design and analysis of thick FML structures.Structural IntegrityAerospace Engineerin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Environmental Magnetism of Oligocene - Miocene Glaciomarine Strata from CRP-2/2A, Victoria Land Basin, Antarctica
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Environmental magnetism of lower Miocene strata from the CRP-1 core, McMurdo Sound, Antarctia
No full text- …
