Automatic construction of interconnected cable models of cardiac propagation on a surface.

The relationship between anatomy and function has long been recognised. Understanding the gross structure, and the myoarchitecture, of the atriums is fundamental to investigations into the substrates and therapy of atrial fibrillation. Based primarily on our experience with normal human hearts, this review provides, firstly, a basis of comparison of gross structures as seen in the clinical situation, and in animals commonly used in experimental studies. Secondly, we discuss the general arrangement of myocardial fibres with respect to gross topography in the normal human heart. The right atrium is dominated by an extensive array of pectinate muscles within the extensive appendage, whereas the left atrium is relatively smooth-walled, with a much smaller tubular appendage. Myoarchitecture displays parallel alignment of fibres along distinct muscle bundles, such as the terminal crest and Bachmann's bundle. Within the smooth wall of the left atrium, there is a marked transmural change in the orientation of the muscular fibres. Abrupt changes in orientation, and mixed arrangements, are common between bundles. Other than Bachmann's bundle, the muscular bridges which provide interatrial connections, and connections between the left atrium and the coronary sinus and inferior caval vein, are highly variable. Inhomogeneities both in gross structure and myoarchitecture are common in the normal heart. These should be taken into account when investigating hearts from patients known to have had a history of arrhythmias, in devising computer models, or when refining diagnostic and therapeutic strategies.

Fracture growth under simple shearing, under transtension, and under transpression has been studied with the maximum strain-energy release-rate criterion Gmax. A repulsion scheme is used to handle the friction contact of the fracture faces. Numerical results show that, under simple shearing or transtension, a fracture grows with an abrupt change in orientation (70° with respect to the fracture), and the trajectory of the fracture growth is smooth and slightly convex. These features are in remarkable agreement with laboratory results obtained by many investigators. Under transpression, a fracture also grows with an abrupt change in orientation, and the smooth trajectory of the fracture growth is slightly concave when the compression is large. The interaction of two fractures under shearing is quite different from that under tensile loading. Under left-lateral shearing, when the two right-stepping fractures are far apart, they run away from each other; when they are close, interaction takes place, and they tend to interconnect. Under right-lateral shearing, a pull-apart basin may form by the growth of two right-stepping fractures.

After deformation of between 50 and 60% by plane strain, a {110}〈112〉 Al single crystal retains its original orientation throughout the whole cross section of the crystal. On cold rolling, however, bands parallel to the rolling plane are formed which show both gradual and abrupt changes of orientation. On annealing, the boundary between two layers with an abrupt change in orientation is a preferred nucleation site and new crystals are nucleated here at an earlier stage and grow faster than from a surface which was severely and randomly abraded for artificial nucleation. The orientations of the recrystallized grains can be directly related to the mode of deformation.

Geometric microstructural damage of white matter with functional compensation in post-stroke

Consumer demand for high resolution and high refresh-rate displays has naturally led to the fabrication of liquid crystal displays with ever smaller pixels. As a consequence, fringing fields between adjacent pixels grow in magnitude, leading to abrupt changes in orientation. Electric field strengths above some threshold can lead to order melting and, in turn, disclinations. This paper presents accurate modeling of disclinations induced by fringing fields due to interdigitated electrodes in a nematic liquid crystal calculated by means of the Landau–de Gennes theory. Disclination paths are determined while taking into account the flow of the liquid crystal. Making use of interdigitated electrodes, precise electrical control over the creation and positioning of defects is demonstrated for homeotropic, planar, hybrid, and in-plane surface alignments.

The southernmost segment of the western Alpine arc, strikes E-W along the Mediterranean coast between Nice and Menton (F), and it is bounded by N-S structures on both sides. These abrupt changes in orientation, and the E-W strike as such in an area located southwest of the Adriatic indenter is difficult to reconcile with alpine collisional displacements. Indeed the latter are inferred to be governed by NW-ward movement of the Adriatic Indenter, which is located NE of our study area. E-W -oriented structures in this area are commonly attributed to the Pyrenean (Pyreneo-Provençal) orogeny, which however does not explain their young, Miocene age. As a consequence this E-W Alpine (?) arc segment has been variously interpreted in the past literature (Brunsmann et al., 2024, for review), as the result of Alpine indentation, Pyrenean-Provençal shortening re-activated in post-Burdigalian times, or gravitational sliding (Gèze, 1956).A 40 km long, NNE-SSW cross-section between the latter localities shows that the tectonic style varies from N to S. The northern sector shows that the Permian and Triassic cover are gently folded above the Argentera crystalline basement. Further south, in the areas of Breil-sur-Roya and Sospel, the Jurassic, Cretaceous and Eocene cover is more tightly folded, showing broadly E-W, steeply-dipping axial planes. However, this entire folded sequence tectonically overlies the very gently-dipping upper Triassic gypsum, forming a subtractive contact, thus a normal-type of displacement. Further south, from Castillon to Cap d’Ail, the entire Triassic to Eocene cover forms a stack of 10 distinct north-dipping thrusts, most of which lying directly above Triassic gypsum.As shown in map view between Sospel and Gorbio, the same gypsum layer can be continuously followed from its normal-fault position in the north to thrust planes in the south, via a thin strike slip fault located between them. We suggest that not only the thrust faults of Gorbio, but even all the others further south are rooted in the gypsum of the normal fault further north.This spatial distribution of normal faults at higher topographic altitude, kinematically linked with thrusts at a deeper topographic level, and all localized along gypsum layers, is analogous to what is frequently observed in the sedimentary sequences of passive margins. Cooling of the oceanic lithosphere causes differential subsidence (e.g., Brun and Fort, 2012), hence tilting of the sedimentary sequence, which initiates downward gliding of the post-Triassic beds. In our case study, the contemporaneous Miocene uplift of the Argentera crystalline massif (Bigot-Cormier et al., 2006) and extensional thinning of the Liguro-Provençal domain (Rollet et al., 2004) tilts the entire Mesozoic sequence allowing for a gradient that induces gliding along the low-viscosity upper triassic gypsum. If this interpretation is correct, a large part of this arc segment does not directly result from Alpine collisional convergence.Bigot-Cormier et al. (2006). Geodinamica Acta, 19, 455-473.Brun, J.-P. and Fort, X. (2011). Marine and Petroleum Geology, 28, 1123-1145.Brunsmann et al. (2024). Comptes Rendus. Géoscience, 356, 231-263.Gèze, B. (1956). Comptes Rendus Académie Sciences,  2733-2735.Rollet et al. (2002). Tectonics, 21, 6-23.

Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Discontinuous reactions are solid state moving boundary phase transitions characterised by a discontinuous or abrupt change in orientation and composition between the matrix phases in the reactant and product aggregate across the migrating boundary or reaction front that provides a short circuit path of diffusion. The reactions include discontinuous precipitation, discontinuous coarsening, discontinuous dissolution, and diffusion induced grain boundary migration. All these reactions may account for a substantial change in microstructure, composition, and material properties, and hence, deserve adequate scientific attention for a better understanding. The present review provides a comprehensive discussion on the current status of understanding about nucleation and growth mechanisms, genesis and driving force, product morphology and distribution, kinetic growth models, and related experimental techniques, and above all, the unresolved questions concerning these discontinuous reactions. In addition, exhaustive lists have been provided to document the important literature on the concerned subjects, whenever possible. Finally, a particular emphasis has been placed on analysing the recent findings about dynamic behaviour of grain boundaries, scope of determination of Arrhenius parameters by kinetic analysis, and orientation/structural dependence of boundary migration and diffusion.

Well‐exposed gypsum veins in the Triassic Moenkopi formation in southern Utah, USA, are similar to veins at Endeavour and Gale Craters on Mars. Both Moenkopi and Mars veins are hydrated calcium sulfate, have fibrous textures, and crosscut other diagenetic features. Moenkopi veins are stratigraphically localized with strontium and sulfur isotope ratios similar to primary Moenkopi sulfate beds and are thus interpreted to be sourced from within the unit. Endeavour veins seem to be distributed by lithology and may have a local source. Gale veins cut across multiple lithologies and appear to be sourced from another stratigraphic interval. Evaluation of vein network geometries indicates that horizontal Moenkopi veins are longer and thicker than vertical veins. Moenkopi veins are also generally oriented with the modern stress field, so are interpreted to have formed in the latest stages of exhumation. Endeavour veins appear to be generally vertical and oriented parallel to the margins of Cape York and are interpreted to have formed in response to topographic collapse of the crater rim. Gale horizontal veins appear to be slightly more continuous than vertical veins and may have formed during exhumation. Abrupt changes in orientation, complex crosscutting relationships, and fibrous (antitaxial) texture in Moenkopi and Mars veins suggest emplacement via hydraulic fracture at low temperatures. Moenkopi and Mars veins are interpreted as late‐stage diagenetic features that have experienced little alteration since emplacement. Moenkopi veins are useful terrestrial analogs for Mars veins because vein geometry, texture, and chemistry record information about crustal deformation and vein emplacement.

Observations and modeling of shelf-slope front seasonal variability between 75°and 50°W

Radar observations made with a polarization diversity radar show the existence of a high degree of common orientation of the particles in the upper levels of thunderstorms. Abrupt changes in orientation associated with lightning discharges have frequently been observed, the particles becoming disoriented, or in some cases reoriented, in less than 1 s. Recovery times of the order of 10–15 s were observed. A consequence of the oriented states is the existence of differential propagation characteristics for radio waves propagating through the medium. A differential phase shift of 2.5°/km at 1.8-cm wavelength is reported for a thunderstorm.

Bailout Strategies for Abrupt Change in Woven Endobridge 17 Device Orientation After Detachments: Technical Note of 2 Anterior Communicating Artery Aneurysm Cases

Carbonado revisited: Insights from neutron diffraction, high resolution orientation mapping and numerical simulations

In this article the Ballbot described as being unlike a statically stable wheeled robot, is shown to be a dynamic stable robot. The stability of such inherently unstable robot is based on accurate angle and position feedback that is obtained from his IMU. We did not use commercial IMU in this Ballbot construction unlike the previous Ballbots, instead an IMU that is suitable for Ballbot mechanism was designed and implemented. Angle feedback produced by IMU must be as accurate as possible, similar to other sections of robot. Because of this reason we must calibrate sensors for best performance. But before sensors calibration, ADC calibration must be done in order to correct errors occurring during conversion of the sensor analog signals to equivalent digital numbers. By a calibrated ADC, sensor calibration is performed. A precise calibration method which is simple to apply is presented. The method does not need accurate equipment and is performed by a plate attached to an ordinary motor. After acquiring calibrated data, the Kalman filter is implemented for data fusion. The Kalman filter output is very accurate and IMU can track abrupt changes in orientation. It is implemented in Ballbot and could provide proper feedback to balance the Ballbot.

VCMM: A visual tool for continuum molecular modeling