| 1. |
- Baud, Maxime O, et al.
(author)
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European trends in epilepsy surgery.
- 2018
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In: Neurology. - 1526-632X. ; 91:2
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Journal article (peer-reviewed)abstract
- Resective surgery is effective in treating drug-resistant focal epilepsy, but it remains unclear whether improved diagnostics influence postsurgical outcomes. Here, we compared practice and outcomes over 2 periods 15 years apart.Sixteen European centers retrospectively identified 2 cohorts of children and adults who underwent epilepsy surgery in the period of 1997 to 1998 (n = 562) or 2012 to 2013 (n = 736). Data collected included patient (sex, age) and disease (duration, localization and diagnosis) characteristics, type of surgery, histopathology, Engel postsurgical outcome, and complications, as well as imaging and electrophysiologic tests performed for each case. Postsurgical outcome predictors were included in a multivariate logistic regression to assess the strength of date of surgery as an independent predictor.Over time, the number of operated cases per center increased from a median of 31 to 50 per 2-year period (p = 0.02). Mean disease duration at surgery decreased by 5.2 years (p < 0.001). Overall seizure freedom (Engel class 1) increased from 66.7% to 70.9% (adjusted p = 0.04), despite an increase in complex surgeries (extratemporal and/or MRI negative). Surgeries performed during the later period were 1.34 times (adjusted odds ratio; 95% confidence interval 1.02-1.77) more likely to yield a favorable outcome (Engel class I) than earlier surgeries, and improvement was more marked in extratemporal and MRI-negative temporal epilepsy. The rate of persistent neurologic complications remained stable (4.6%-5.3%, p = 0.7).Improvements in European epilepsy surgery over time are modest but significant, including higher surgical volume, shorter disease duration, and improved postsurgical seizure outcomes. Early referral for evaluation is required to continue on this encouraging trend.
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| 2. |
- Cremades, Andrés, et al.
(author)
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Identifying regions of importance in wall-bounded turbulence through explainable deep learning
- 2024
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In: Nature Communications. - : Nature Research. - 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- Despite its great scientific and technological importance, wall-bounded turbulence is an unresolved problem in classical physics that requires new perspectives to be tackled. One of the key strategies has been to study interactions among the energy-containing coherent structures in the flow. Such interactions are explored in this study using an explainable deep-learning method. The instantaneous velocity field obtained from a turbulent channel flow simulation is used to predict the velocity field in time through a U-net architecture. Based on the predicted flow, we assess the importance of each structure for this prediction using the game-theoretic algorithm of SHapley Additive exPlanations (SHAP). This work provides results in agreement with previous observations in the literature and extends them by revealing that the most important structures in the flow are not necessarily the ones with the highest contribution to the Reynolds shear stress. We also apply the method to an experimental database, where we can identify structures based on their importance score. This framework has the potential to shed light on numerous fundamental phenomena of wall-bounded turbulence, including novel strategies for flow control.
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| 3. |
- Deshpande, Rahul, et al.
(author)
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Reynolds-number effects on the outer region of adverse-pressure-gradient turbulent boundary layers
- 2023
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In: Physical Review Fluids. - : American Physical Society (APS). - 2469-990X. ; 8:12
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Journal article (peer-reviewed)abstract
- We study the Reynolds-number effects on the outer region of moderate adverse-pressure-gradient (APG) turbulent boundary layers (TBLs) and find that their small-scale (viscous) energy reduces with increasing friction Reynolds number (Reτ). The trend is based on analyzing APG TBL data across 600≲Reτ≲7000 and contrasts with the negligible variation in small viscous-scaled energy noted for canonical wall flows. The data sets considered include those from a well-resolved numerical simulation [Pozuelo, J. Fluid Mech. 939, A34 (2022)0022-112010.1017/jfm.2022.221], which provides access to an APG TBL maintained at near-equilibrium conditions across 1000≲Reτ≲ 2000, with a well-defined flow history, and a new high-Reτ (∼7000) experimental study from the large Melbourne wind tunnel, with its long test section modified to permit development of an APG TBL from a "canonical"upstream condition. The decrease in small-scale energy with Reτ is revealed via decomposing the streamwise normal stresses into small- and large-scale contributions, based on a sharp spectral cutoff. The origin for this trend is traced back to the production of turbulent kinetic energy in an APG TBL, the small-scale contribution to which is also found to decrease with Reτ in the outer region. The conclusion is reaffirmed by investigating attenuation of streamwise normal stresses due to changing spatial resolutions of the numerical grid or hotwire sensors, which reduces with increasing Reτ and is found to be negligible at Reτ∼7000 in this study. The results emphasize that new scaling arguments and spatial-resolution corrections should be tested rigorously across a broad Reτ range, particularly for pressure gradient TBLs.
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