Norwegian Academy of Science and Letters

About: Norwegian Academy of Science and Letters is a education organization based out in Oslo, Norway. It is known for research contribution in the topics: Population & Magnetic field. The organization has 129 authors who have published 178 publications receiving 10014 citations. The organization is also known as: Det Norske Videnskaps-Akademi & DNVA.

Betula: a prospective cohort study on memory, health, and aging

Abstract: This article describes the Betula Study with respect to objectives, design, participants, and assessment instruments for health and cognition. Three waves of data collection have been completed in 5-year intervals since 1988–1990. A fourth wave started in 2003 and will be completed in 2005. An overview of Betula research is presented under the headings of memory and cognition and cognitive neuroscience. Health-related issues and sex differences as well as comparisons between cross-sectional and longitudinal studies are discussed in the first section. The influence of different genes and of some brain abnormalities for memory functioning in adulthood and old age constitute main topics in the second section. New data are presented on the association between blood pressure and dementia. We demonstrated that a demented group of participants had higher levels of systolic blood pressure and pulse pressure than non-dementia controls 10 years before diagnosis. The new fourth wave of data collection will, in addit...

Acceleration and deceleration of India-Asia convergence since the Cretaceous: Roles of mantle plumes and continental collision

Abstract: [1] A strong 50–35 Ma decrease in India-Asia convergence is generally ascribed to continent-continent collision. However, a convergence rate increase of similar magnitude occurred between ∼65–50 Ma. An earlier increase occurred at ∼90 Ma. Both episodes of accelerated convergence followed upon arrival of a mantle plume below and emplacement of a large igneous province (LIP) on the Indian plate. We here first confirm these convergence rate trends, reassessing the Indo-Atlantic plate circuits. Then, using two different numerical models, we assess whether plume head arrival and its lateral asthenospheric flow may explain the plate velocity increases and whether decreased plume flux and increasing continent-plume distance may explain deceleration, even without continental collision. The results show that plume head arrival can indeed lead to absolute Indian plate motion accelerations on the order of several cm/yr, followed by decelerations on timescales similar to the reconstructed fluctuations. The 90 Ma increase could potentially be explained as response to the Morondova mantle plume alone. The 65–50 Ma convergence rate increase, however, is larger than can be explained by plume head spreading alone. We concur with previous hypotheses that plume-induced weakening of the Indian continental lithosphere-asthenosphere coupling and an increased slab pull and ridge push efficiency are the most likely explanations for the large convergence rate increase. The post-50 Ma decrease is best explained by orogeny-related increased trench resistivity, decreased slab pull due to continental subduction, and possibly restrengthening of lithosphere-asthenosphere coupling upon plume demise.