24 research outputs found

    Use of anticoagulants and antiplatelet agents in stable outpatients with coronary artery disease and atrial fibrillation. International CLARIFY registry

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    Problems of the Upper Mantle and Hawaii as a Site for the Moho Hole

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    Volume: 19Start Page: 271End Page: 28

    A Review of Satellite-Derived Figures of the Geoid and Their Geophysical Significance

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    One of the major geodetic results that has come out of the satellite tracking program, in addition to the revision of the degree of polar flattening for the Earth, is that the Earth is characterized by a series of previously undefined geoidal highs and lows. As these cannot be correlated with the surface mass distribution defined by the continents and ocean basins, they presumably are related to regional variations in gravity resulting from the mass distributions within the Earth. That they may have other geophysical as well as geological significance has been proposed by various investigators (Lee and MacDonald, 1963; Wang, 1963 ; Runcorn, 1964 ; Baussus, 1960 ; Vogel, 1960; Scheffer, 1966; Strange, 1966) . However, the geoidal pattern defined by different investigators has not been totally consistent in that there are differences both in basic pattern and in magnitude of the geoidal undulations. There has also been an evolutionary trend in the complexity of the geoidal pattern defined. This change in overall pattern, as well as the differences in pattern obtained by different investigators, can be related to the sampling of data used (number of satellites and their orbital elements as well as number and distribution of tracking stations); the type of tracking data used (optical versus electronic doppler observations); the parameters of the reference ellipsoid used (particularly the degree of polar flattening ) ; the degree of fit as represented by the order and degree of the coefficient terms and their derived values; and the combinations of data used, such as satellite plus surface gravity observations. There have also been studies based entirely on surface gravity observations which have been influenced in various degrees by the assumptions made by different investigators for the surface gravity field where there are no observational data

    Crustal and mantle relationships as a function of geologic age and heat Flow from the east Pacific rise out into the Pacific basin

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    La velocidad media de la corteza rocosa cristalina, su · espesor y la velocidad del manto superior son parámetros que varian. significativamente y que se relacionan de diversas maneras con la edad geológica y con el flujo térmico. Exceptuándose la zona de bajo flujo térmico en los flancos de las dorsales oceánicas, donde la corteza es delgada y. la velocidad de la corteza está en razón inversa a la del manto, dichas velocidades tienden a aumentar progresivamente con la distancia de la cresta, y con la profundidad del océano y la edad geológica hasta unos 63 millones de años. En este punto hay una reducción significativa de la velocidad media de la corteza, la velocidad del manto y del espesor de la corteza, junto con una pequeña perturbación positiva del flujo térmico. Para las edades comprendidas entre 76 a 120 m.a., el espesor de la corteza vuelve a aumentar con la edad, con la distancia de la cresta y con la profundidad marina. Este incremento de espesor de la corteza parece estar relacionado inversamente con el cambio en la velocidad del manto con escasos cambios de la velocidad media en la corteza, y en general el flujo térmico disminuye durante este periodo para edades superiores a 120 m.a. ya no hay cambios significativos en los espesores de la corteza ni en las profundidades marinas, si bien los datos disponibles parecen indicar que aumenta la velocidad del manto, con un ligero aumento concomitante en la velocidad media de la corteza, y en el flujo térmico
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