Three‐dimensional turbulence‐resolving simulations of the plunge phenomenon in a tilted channel

Hyperpycnal flows are produced when the density of a fluid flowing in a relatively quiescent basin is greater than the density of the fluid in the basin. The density differences can be due to the difference in temperatures, salinity, turbidity, concentration, or a combination of them. When the inflow momentum diminishes, the inflowing fluid eventually plunges under the basin fluid and flows along the bottom floor as an underflow density current. In the present work, 3‐D turbulence‐resolving simulations are performed for an hyperpycnal flow evolving at the bottom floor of a tilted channel. Using advanced numerical techniques designed for supercomputers, the incompressible Navier‐Stokes and transport equations are solved to reproduce numerically the experiments of Lamb et al. (2010, https://doi.org/10.1130/B30125.1) obtained inside a flume with a long tilted ramp. This study focuses on presenting and validating a new numerical framework for the correct reproduction and analysis of the plunge phenomenon and its associated flow features. A very good agreement is found between the experimental data of Lamb et al. (2010), the analytical models of Parker and Toniolo (2007, https://doi.org/10.1061/(ASCE)0733-9429(2007)133:6(690)), and the present turbulence‐resolving simulations. The mixing process between the ambient fluid and the underflow density current is also analyzed thanks to visualizations of vortical structures at the interface

Energy Consumption Forecasting Using Ensemble Learning Algorithms

DCAI 2019: Distributed Computing and Artificial Intelligence, 16th International Conference, Special SessionsThe increase of renewable energy sources of intermittent nature has brought several new challenges for power and energy systems. In order to deal with the variability from the generation side, there is the need to balance it by managing consumption appropriately. Forecasting energy consumption becomes, therefore, more relevant than ever. This paper presents and compares three different ensemble learning methods, namely random forests, gradient boosted regression trees and Adaboost. Hour-ahead electricity load forecasts are presented for the building N of GECAD at ISEP campus. The performance of the forecasting models is assessed, and results show that the Adaboost model is superior to the other considered models for the one-hour ahead forecasts. The results of this study compared to previous works indicates that ensemble learning methods are a viable choice for short-term load forecast.This work has received funding from National Funds through FCT (Fundaçao da Ciencia e Tecnologia) under the project SPET – 29165, call SAICT 2017.info:eu-repo/semantics/publishedVersio

Low-cost reusable instrumentation for laparoendoscopic single-site nephrectomy: assessment in a porcine model

PURPOSE: To test different sets of prebent instruments and a new reusable access device for laparoendoscopic single-site (LESS) surgery. MATERIALS AND METHODS: Three surgeons with previous experience in LESS performed 12 nephrectomies in six pigs. In all procedures, a multichannel access device (X-CONE) and a 5-mm extra-long telescope were used. Four sets of prebent instruments with different profiles (S-portal) were tested: Standard (one straight scissors and one curved grasper), Cuschieri, Carus, and Leroy set (each of them consisting of two curved instruments with different configurations). Assessment was performed based on both objective (procedure time; time to manage the pedicle; time to free kidney) and subjective parameters (entry/exit of instruments; triangulation; dissection up/down; dissection lateral; retraction; interdependence). The subjective assessment tool used was a Likert type scale (1 = easy to 5 = prohibitive). The access device was assessed by using objective (time to complete insertion of device after skin incision) and subjective (significant air leakage, movement constraint) parameters. RESULTS: Time to insertion of the X-CONE was <1 minute in all the cases. Surgeons reported significant insufflant leakage in 58% of cases. The procedure was completed in 10/12 (83%) cases. Mean operative time was 8.3 ± 4.2 minutes, being lower for the Carus group (4.5 min) and higher for the standard group (13 min). Among the different sets, the standard one obtained the best mean scores for all subjective parameters. CONCLUSIONS: X-CONE allows easy abdominal access, and its reusable properties represent cost savings for LESS compared with disposable devices. Prebent instruments might also represent attractive low-cost tools for LESS

Low-cost reusable instrumentation for laparoendoscopic single-site nephrectomy: assessment in a porcine model

PURPOSE: To test different sets of prebent instruments and a new reusable access device for laparoendoscopic single-site (LESS) surgery. MATERIALS AND METHODS: Three surgeons with previous experience in LESS performed 12 nephrectomies in six pigs. In all procedures, a multichannel access device (X-CONE) and a 5-mm extra-long telescope were used. Four sets of prebent instruments with different profiles (S-portal) were tested: Standard (one straight scissors and one curved grasper), Cuschieri, Carus, and Leroy set (each of them consisting of two curved instruments with different configurations). Assessment was performed based on both objective (procedure time; time to manage the pedicle; time to free kidney) and subjective parameters (entry/exit of instruments; triangulation; dissection up/down; dissection lateral; retraction; interdependence). The subjective assessment tool used was a Likert type scale (1 = easy to 5 = prohibitive). The access device was assessed by using objective (time to complete insertion of device after skin incision) and subjective (significant air leakage, movement constraint) parameters. RESULTS: Time to insertion of the X-CONE was <1 minute in all the cases. Surgeons reported significant insufflant leakage in 58% of cases. The procedure was completed in 10/12 (83%) cases. Mean operative time was 8.3 ± 4.2 minutes, being lower for the Carus group (4.5 min) and higher for the standard group (13 min). Among the different sets, the standard one obtained the best mean scores for all subjective parameters. CONCLUSIONS: X-CONE allows easy abdominal access, and its reusable properties represent cost savings for LESS compared with disposable devices. Prebent instruments might also represent attractive low-cost tools for LESS

Serial clustering of extratropical cyclones in a multi-model ensemble of historical and future simulations

This study has investigated serial (temporal) clustering of extra-tropical cyclones simulated by 17 climate models that participated in CMIP5. Clustering was estimated by calculating the dispersion (ratio of variance to mean) of 30 December-February counts of Atlantic storm tracks passing nearby each grid point. Results from single historical simulations of 1975-2005 were compared to those from historical ERA40 reanalyses from 1958-2001 ERA40 and single future model projections of 2069-2099 under the RCP4.5 climate change scenario. Models were generally able to capture the broad features in reanalyses reported previously: underdispersion/regularity (i.e. variance less than mean) in the western core of the Atlantic storm track surrounded by overdispersion/clustering (i.e. variance greater than mean) to the north and south and over western Europe. Regression of counts onto North Atlantic Oscillation (NAO) indices revealed that much of the overdispersion in the historical reanalyses and model simulations can be accounted for by NAO variability. Future changes in dispersion were generally found to be small and not consistent across models. The overdispersion statistic, for any 30 year sample, is prone to large amounts of sampling uncertainty that obscures the climate change signal. For example, the projected increase in dispersion for storm counts near London in the CNRMCM5 model is 0.1 compared to a standard deviation of 0.25. Projected changes in the mean and variance of NAO are insufficient to create changes in overdispersion that are discernible above natural sampling variations

Analysing the Impact of Rationality on the Italian Electricity Market

International audienceWe analyze the behavior of the Italian electricity market with an agent-based model. In particular, we are interested in testing the assumption that the market participants are fully rational in the economical sense. To this aim, we extend a previous model by considering a wider class of cases. After checking that the new model is a correct generalization of the existing model, we compare three optimization methods to implement the agents rationality and we verify that the model exhibits a very good fit to the real data. This leads us to conclude that our model can be used to predict the behavior of this market

Mediterranean cyclones and windstorms in a changing climate

Changes in the frequency and intensity of cyclones and associated windstorms affecting the Medi-terranean region simulated under enhanced Greenhouse Gas forcing conditions are investigated. The analysis is based on 7 climate model integrations performed with two coupled global models (ECHAM5 MPIOM and INGV CMCC), comparing the end of the twentieth century and at least the first half of the twenty-first century. As one of the models has a considerably enhanced resolution of the atmosphere and the ocean, it is also investigated whether the climate change signals are influenced by the model resolution. While the higher resolved simulation is closer to reanalysis climatology, both in terms of cyclones and windstorm distributions, there is no evidence for an influence of the resolution on the sign of the climate change signal. All model simulations show a reduction in the total number of cyclones crossing the Mediterranean region under climate change conditions. Exceptions are Morocco and the Levant region, where the models predict an increase in the number of cyclones. The reduction is especially strong for intense cyclones in terms of their Laplacian of pressure. The influence of the simulated positive shift in the NAO Index on the cyclone decrease is restricted to the Western Mediterranean region, where it explains 10–50 % of the simulated trend, depending on the individual simulation. With respect to windstorms, decreases are simulated over most of the Mediterranean basin. This overall reduction is due to a decrease in the number of events associated with local cyclones, while the number of events associated with cyclones outside of the Mediterranean region slightly increases. These systems are, however, less intense in terms of their integrated severity over the Mediterranean area, as they mostly affect the fringes of the region. In spite of the general reduction in total numbers, several cyclones and windstorms of intensity unknown under current climate conditions are identified for the scenario simulations. For these events, no common trend exists in the individual simulations. Thus, they may rather be attributed to long-term (e.g. decadal) variability than to the Greenhouse Gas forcing. Nevertheless, the result indicates that high-impact weather systems will remain an important risk in the Mediterranean Basin

Prevalence of hepatitis B virus marker positivity and evolution of hepatitis B virus profile, during chemotherapy, in patients with solid tumours

To prospectively evaluate the prevalence of hepatitis B virus (HBV) positivity and study the evolution of HBV profile during cancer chemotherapy, serum HBV markers and liver biochemistry were determined in 1008 of 1402 (72%) cancer patients admitted in our Unit and in all 920 (91%) who received chemotherapy. We found that 54 (5.3%) were HBsAg carriers while 443 (44%) had at least one HBV marker positive. Of the latter, 405 (91%) were HBcAb+ve, 321 (72%) HBsAb+ve and 212 (48%) HBeAb+ve. No patient was HBeAg+ve. Among 920 chemotherapy receivers, 374 (41%) were HBcAb+ve, 280 (30%) HBsAb+ve and 178 (19%) HBeAb+ve. Fifty (5.4%) were HBsAg carriers (versus 0.6% in Greek blood donors). All 50 were systematically screened for HBsAg and HBsAb status throughout chemotherapy, during follow-up or until their death, and liver biochemistry was performed before each chemotherapy course. Stable antigenaemia was observed in 43/50 (86%) while 7/50 (14%) developed clinical and/or biochemical hepatitis. Six of these seven developed serum anti-HBs antibodies with an associated decrease of serum HBsAg titres. We conclude that reactivation of HBV infection during chemotherapy is not rare (14%), while disappearance of HBs antigenaemia is neither a frequent nor usually a permanent phenomenon. © 1999 Cancer Research Campaig

Intra- and interreader reproducibility of PI-RADSv2: A multireader study

Background: The Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) has been in use since 2015; while interreader reproducibility has been studied, there has been a paucity of studies investigating the intrareader reproducibility of PI-RADSv2. Purpose: To evaluate both intra- and interreader reproducibility of PI-RADSv2 in the assessment of intraprostatic lesions using multiparametric magnetic resonance imaging (mpMRI). Study Type: Retrospective. Population/Subjects: In all, 102 consecutive biopsy-naïve patients who underwent prostate MRI and subsequent MR/transrectal ultrasonography (MR/TRUS)-guided biopsy. Field Strength/Sequences: Prostate mpMRI at 3T using endorectal with phased array surface coils (TW MRI, DW MRI with ADC maps and b2000 DW MRI, DCE MRI). Assessment: Previously detected and biopsied lesions were scored by four readers from four different institutions using PI-RADSv2. Readers scored lesions during two readout rounds with a 4-week washout period. Statistical Tests: Kappa (κ) statistics and specific agreement (Po) were calculated to quantify intra- and interreader reproducibility of PI-RADSv2 scoring. Lesion measurement agreement was calculated using the intraclass correlation coefficient (ICC). Results: Overall intrareader reproducibility was moderate to substantial (κ = 0.43–0.67, Po = 0.60–0.77), while overall interreader reproducibility was poor to moderate (κ = 0.24, Po = 46). Readers with more experience showed greater interreader reproducibility than readers with intermediate experience in the whole prostate (P = 0.026) and peripheral zone (P = 0.002). Sequence-specific interreader agreement for all readers was similar to the overall PI-RADSv2 score, with κ = 0.24, 0.24, and 0.23 and Po = 0.47, 0.44, and 0.54 in T2-weighted, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE), respectively. Overall intrareader and interreader ICC for lesion measurement was 0.82 and 0.71, respectively. Data Conclusion: PI-RADSv2 provides moderate intrareader reproducibility, poor interreader reproducibility, and moderate interreader lesion measurement reproducibility. These findings suggest a need for more standardized reader training in prostate MRI. Level of Evidence: 2. Technical Efficacy: Stage 2

Response of the North Atlantic storm track to climate change shaped by ocean–atmosphere coupling

A poleward shift of the mid-latitude storm tracks in response to anthropogenic greenhouse-gas forcing has been diagnosed in climate model simulations1, 2. Explanations of this effect have focused on atmospheric dynamics3, 4, 5, 6, 7. However, in contrast to storm tracks in other regions, the North Atlantic storm track responds by strengthening and extending farther east, in particular on its southern flank8. These adjustments are associated with an intensification and extension of the eddy-driven jet towards western Europe9 and are expected to have considerable societal impacts related to a rise in storminess in Europe10, 11, 12. Here, we apply a regression analysis to an ensemble of coupled climate model simulations to show that the coupling between ocean and atmosphere shapes the distinct storm-track response to greenhouse-gas forcing in the North Atlantic region. In the ensemble of simulations we analyse, at least half of the differences between the storm-track responses of different models are associated with uncertainties in ocean circulation changes. We compare the fully coupled simulations with both the associated slab model simulations and an ocean-forced experiment with one climate model to establish causality. We conclude that uncertainties in the response of the North Atlantic storm track to anthropogenic emissions could be reduced through tighter constraints on the future ocean circulation