Normal Modes of the Structural Connectome

Division of the human cortex into distinct regions is of high importance to neuroscientific inquiry. Fully-automated, multi-modal schemes of achieving such parcellation on an individual subject basis are particularly advantageous, however difficulties in inter-modal and inter-subject registration of brain images, as well as obstacles in preserving group-level correspondence of individual parcellation maps have slowed progress in this area. In parallel, there exists a relative dearth of data-driven parcellation schemes that incorporate high resolution structural connectivity metrics; the majority of widely-accepted parcellation maps in the literature have primarily used functional connectivity. Here, a fully data-driven, automated routine based on structural geometry and connectivity which achieves subject-specific cortical parcellation maps while maintaining group-level correspondence of maps is presented and optimized. Using high resolution white matter surface meshes and advanced fiber tracking techniques, a novel vertex-wise structural connectivity graph is constructed for each of 10 unrelated subjects, and the first k eigenvectors of the Laplacian Matrix of the graph's adjacency matrix are calculated. These eigenvectors represent the steady-state modes of vibration of the manifold described by this graph, and thus provide subject-specific maps of modes of connectivity in white matter. In order to obtain parcellations at varying levels of coarseness of the cortex from these eigenvectors, hierarchical agglomerative clustering is then performed on the surface mesh, where each vertex's feature vector is its profile in spectral space. Further, a multi-layer graph of all subjects is constructed, and individual parcellations with group level correspondence are obtained by agglomerative clustering of the eigenvectors of the laplacian matrix of the multi-layer graph.Bachelor of Scienc

2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation: executive summary.

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withdrawn 2017 hrs ehra ecas aphrs solaece expert consensus statement on catheter and surgical ablation of atrial fibrillation

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Pedestrian locomotion energetics and gait characteristics of a diving bird, the great cormorant, Phalacrocorax carbo

Great cormorants Phalacrocorax carbo are foot propelled diving birds that seem poorly suited to locomotion on land. They have relatively short legs, which are presumably adapted for the generation of high forces during the power stroke of aquatic locomotion, and walk with a pronounced “clumsy waddle”. We hypothesise (1) that the speed, independent minimum cost of locomotion (C min, ml O2 m−1) will be high for cormorants during treadmill exercise, and (2) that cormorants will have a relatively limited speed range in comparison to more cursorial birds. We measured the rate of oxygen consumption VO2 of cormorants during pedestrian locomotion on a treadmill, and filmed them to determine duty factor (the fraction of stride period that the foot is in contact with the ground), foot contact time (t c), stride frequency (f), swing phase duration and stride length. C min was 2.1-fold higher than that predicted by their body mass and phylogenetic position, but was not significantly different from the C min of runners (Galliformes and Struthioniformes). The extrapolated y-intercept of the relationship between VO2 and speed was 1.9-fold higher than that predicted by allometry. Again, cormorants were not significantly different from runners. Contrary to our hypothesis, we therefore conclude that cormorants do not have high pedestrian transport costs. Cormorants were observed to use a grounded gait with two double support phases at all speeds measured, and showed an apparent gait transition between 0.17 and 0.25 m s−1. This transition occurs at a Froude number between 0.016 and 0.037, which is lower than the value of ~0.5 observed for many other species. However, despite the use of a limited speed range, and a gait transition at relatively low speed, we conclude that the pedestrian locomotion of these foot propelled diving birds is otherwise generally similar to that of cursorial birds at comparable relative velocities