A hybrid technique that combines an artificial neural network with a particle swarm optimization (ANN+PSO) was used to forecast the disturbance storm time (Dst) index from 1 to 6 h ahead. Our ANN was optimized by PSO to update ANN weights and to predict the short‐term Dst index using past values as input parameters. The database used contains 233,760 hourly data from 1 January 1990 to 31 August 2016, considering storms and quiet period, grouped into three data sets: learning set (with 116,880 hourly data points), validation set (with 58,440 data points), and testing set (with 58,440 data points). Several ANN topologies were studied, and the best architecture was determined by systematically adding neurons and evaluating the root‐mean‐square error (RMSE) and the correlation coefficient (R) during the training process. These results show that the hybrid algorithm is a powerful technique for forecasting the Dst index a short time in advance like t + 1 to t + 3, with RMSE from 3.5 nT to 7.5 nT, and R from 0.98 to 0.90. However, t + 4 to t + 6 predictions become slightly more uncertain, with RMSE from 8.8 nT to 10.9 nT, and R from 0.86 to 0.79. Additionally, an exhaustive analysis according to geomagnetic storm magnitude was conducted. In general, the results show that our hybrid algorithm can be correctly trained to forecast the Dst index with appropriate precision and that Dst past behavior significantly affects adequate training and predicting capabilities of the implemented ANN.
The radiological protocol used shows a high sensitivity and excellent specificity for detecting the cerebral circulatory arrest that accompanies BD. As a rapid, non-invasive, and widely available technique it is a promising alternative to conventional 4-vessel angiography.
Pipeline Flex represents a major advance in FDS technology. The redesigned system has significantly improved the deployment of the Pipeline stent, by enabling the operator to resheath the device. It has the potential to continue revolutionizing the endovascular approach for intracranial aneurysms.
The Pipeline Flex embolization device allows more precise and controlled deployment than the first-generation device. The number of devices and the complication rate during the learning curve are lower than reported with the first-generation PED. The new delivery system and the resheathing maneuvers do not seem to increase the intraprocedural complication rate in comparison with the first-generation PED.
The pipeline embolization device provides a feasible and technically safe solution for aneurysms at and beyond the circle of Willis. Preliminary results are promising but larger series with longer term follow-up examinations are required to show the long term safety and durability of this treatment alternative.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.