East African topography and volcanism explained by a single, migrating plume

Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes. Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa. We devise paleogeographically constrained global models of mantle convection and, based on the evolution of flow in the deepest lower mantle, show that the Afar plume migrated southward throughout its lifetime. The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system (EARS), which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone, over the last ≈45 Myrs. We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate. The models suggest that the Afar plume became weaker as it migrated southwards, consistent with trends observed in the geochemical record

Homogeneous quasimorphisms on the symplectic linear group

We prove a uniqueness theorem for homogeneous quasimorphisms on the universal cover of the symplectic linear grou

Principles and approaches for the machining simulation of ceramic matrix composites at microscale: a review and outlook

Ceramic Matrix Composites (CMC) are advanced materials composed of ceramic fibers embedded in a ceramic matrix, resulting in a highly durable and lightweight composite structure offering exceptional high-temperature performance, excellent mechanical properties, and superior resistance to wear and corrosion. CMC find applications in industries such as aerospace, automotive, energy, and defense, where high strength and thermal stability are crucial. Despite their numerous advantages, machining CMC presents unique challenges. The hardness and brittleness of ceramics make them difficult to machine using conventional methods. The abrasive nature of ceramic particles can rapidly wear down cutting tools, leading to decreased tool life and increased costs. Numeric simulations for the machining of CMC are therefore particularly interesting due to their ability to provide insights into tool-material interactions and optimize machining parameters without the need for expensive and time-consuming physical trials. This paper discusses existing methods and approaches from different materials like Carbon Fiber Reinforced Plastics (CFRP) and monolithic ceramics and puts forward an outlook for the numerical simulation of the machining process of CMC

SIMULATION OF VIBRATIONS IN ALPINE SKIING

Introduction: Simulation of movements has become a significant method in biomechanical research. Especially in alpine ski racing, which is characterized by a great variety of situations, this method is of crucial importance. The main component in alpine skiing technique is the control of vertical load distribution. A few studies have showed that this coordinating capability is considerably influenced by physical conditions. On the one hand, the physical load is related to high external forces, on the other hand, it is the result of oscillating ground reaction forces. The lack of knowledge of how to control vibrations in alpine skiing was the reason for this study. Because of the difficulties in analyzing neurophysiological parameters on the ski slopes, we have developed a simulation system to obtain more information about the control of vibrations in alpine skiing. Methods: To generate vibrations we used a roller ski system with eccentric rolls driven by a treadmill. In view of the results of field studies and theoretical considerations, we worked with a vibration frequency between 4 and 20 Hz and an amplitude between 4 and 21 mm. One group of persons involved in the study were ski teachers from the ‘German Ski Teachers’ Federation’, the other group were recreational skiers. The subjects were subjected to vibrations for about 20 sec. in an upright stance and for the same time in a crouching stance. To measure the generated vibrations and their influence on body movements we used a one dimensional acceleration sensor attached to the middle of the central axis of the ski (sampling frequency 500 Hz), a goniometer (attached to the right knee) and a video system. To assess the vibration control abilities of the subjects we used the parameters ‘resultant acceleration’ and ’amplitude of knee angle’. Results and Discussion: Depending on the used frequency and amplitude the maximum acceleration reached +50/-40 g, the average maximum acceleration in the course of 15 sec. reached +40/-30 g. The data for acceleration measurements on the slope proved to be similar. The statistical data analysis showed significant intra-individual (upright stance/crouching stance) and inter-individual (ski teacher/ recreational skier) differences in resultant acceleration and amplitude of knee angle. The differences depend on the characteristics of the vibration. Conclusion: At this point in our research, we believe that there is an individual optimum of vibration control in regard to frequency and amplitude, depending on anthromethric measurements and physical conditions. These aspects are being researched in a current study

East African topography and volcanism explained by a single, migrating plume

Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes. Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa. We devise paleogeographically constrained global models of mantle convection and, based on the evolution of flow in the deepest lower mantle, show that the Afar plume migrated southward throughout its lifetime. The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system (EARS), which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone, over the last ≈45 Myrs. We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate. The models suggest that the Afar plume became weaker as it migrated southwards, consistent with trends observed in the geochemical record

Comparing Charlson and Elixhauser comorbidity indices with different weightings to predict in-hospital mortality: an analysis of national inpatient data

Understanding how comorbidity measures contribute to patient mortality is essential both to describe patient health status and to adjust for risks and potential confounding. The Charlson and Elixhauser comorbidity indices are well-established for risk adjustment and mortality prediction. Still, a different set of comorbidity weights might improve the prediction of in-hospital mortality. The present study, therefore, aimed to derive a set of new Swiss Elixhauser comorbidity weightings, to validate and compare them against those of the Charlson and Elixhauser-based van Walraven weights in an adult in-patient population-based cohort of general hospitals.; Retrospective analysis was conducted with routine data of 102 Swiss general hospitals (2012-2017) for 6.09 million inpatient cases. To derive the Swiss weightings for the Elixhauser comorbidity index, we randomly halved the inpatient data and validated the results of part 1 alongside the established weighting systems in part 2, to predict in-hospital mortality. Charlson and van Walraven weights were applied to Charlson and Elixhauser comorbidity indices. Derivation and validation of weightings were conducted with generalized additive models adjusted for age, gender and hospital types.; Overall, the Elixhauser indices, c-statistic with Swiss weights (0.867, 95% CI, 0.865-0.868) and van Walraven's weights (0.863, 95% CI, 0.862-0.864) had substantial advantage over Charlson's weights (0.850, 95% CI, 0.849-0.851) and in the derivation and validation groups. The net reclassification improvement of new Swiss weights improved the predictive performance by 1.6% on the Elixhauser-van Walraven and 4.9% on the Charlson weights.; All weightings confirmed previous results with the national dataset. The new Swiss weightings model improved slightly the prediction of in-hospital mortality in Swiss hospitals. The newly derive weights support patient population-based analysis of in-hospital mortality and seek country or specific cohort-based weightings

Strengthening tRansparent reporting of reseArch on uNfinished nursing CARE: The RANCARE guideline

Unfinished, rationed, missed, or otherwise undone nursing care is a phenomenon observed across health-care settings worldwide. Irrespective of differing terminology, it has repeatedly been linked to adverse outcomes for both patients and nursing staff. With growing numbers of publications on the topic, scholars have acknowledged persistent barriers to meaningful comparison across studies, settings, and health-care systems. The aim of this study was thus to develop a guideline to strengthen transparent reporting in research on unfinished nursing care. An international four-person steering group led a consensus process including a two-round online Delphi survey and a workshop with 38 international experts. The study was embedded in the tRansparent reporting of reseArch on uNfinished nursing CARE (RANCARE) COST Action. Participation was voluntary. The resulting 40-item RANCARE guideline provides recommendations for transparent and comprehensive reporting on unfinished nursing care regarding conceptualization, measurement, contextual information, and data analyses. By increasing the transparency and comprehensiveness in reporting of studies on unfinished nursing care, the RANCARE guideline supports efficient use of the research results, for example, allowing researchers and nurses to take purposeful actions, with the goal of improving the safety and quality of health-care services

Novel Application of Polymer Networks Carrying Tertiary Amines as a Catalyst Inside Microflow Reactors Used for Knoevenagel Reactions

A novel application is described for utilizing hydrogel dots as organocatalyst carriers inside microfluidic reactors. Tertiary amines were covalently immobilized in the hydrogel dots. Due to the diffusion of reactants within the swollen hydrogel dots, the accessible amount of catalysts inside a microfluidic reactor chamber can be increased compared to the accessible amount of surface-bound catalysts. To perform fast Knoevenagel reactions, important flow parameters had to be validated to optimize the reactor performance while keeping the dimensions of the reactor chamber constant; e.g. the height of the hydrogel dots had to be adjusted to the invariable dimensions of the reactor chamber, or an adjustment of organocatalysts in the hydrogel dots had to be validated to achieve the highest conversion rate during a certain residence time. To characterize the conversion, nuclear magnetic resonance (NMR) and UV/Vis-spectroscopy were utilized as an offline and online method, respectively. With suitable hydrogel dots, the influence of different flow parameters (e.g., operating flow rate and reactant concentration) on the selected model reactions in the microfluidic reactor was investigated. Finally, a variety of reactants were screened with the optimized flow parameters. With these results, the turnover frequency was determined for the Knoevenagel reactions in a microfluidic reactor, and the results were compared with published data that were determined by other synthetic approaches. © 2020 The Authors published by Wiley-VCH Gmb