Bayesian optimization of massive material injection for disruption mitigation in tokamaks

A Bayesian optimization framework is used to investigate scenarios for disruptions mitigated with combined deuterium and neon injection in ITER. The optimization cost function takes into account limits on the maximum runaway current, the transported fraction of the heat loss and the current quench time. The aim is to explore the dependence of the cost function on injected densities, and provide insights into the behaviour of the disruption dynamics for representative scenarios. The simulations are conducted using the numerical framework Dream (Disruption Runaway Electron Analysis Model). We show that, irrespective of the quantities of the material deposition, multi-megaampere runaway currents will be produced in the deuterium-tritium phase of operations, even in the optimal scenarios. However, the severity of the outcome can be influenced by tailoring the radial profile of the injected material; in particular, if the injected neon is deposited at the edge region it leads to a significant reduction of both the final runaway current and the transported heat losses. The Bayesian approach allows us to map the parameter space efficiently, with more accuracy in favourable parameter regions, thereby providing us with information about the robustness of the optima

Episodic Abdominal Pain Characteristics Are Not Associated with Clinically Relevant Improvement of Health Status After Cholecystectomy

Background:  Cholecystectomy is the therapy of first choice in patients with uncomplicated symptomatic cholecystolithiasis, but it remains unclear which patients truly benefit in terms of health status improvement. Patients generally present with episodic abdominal pain of varying frequency, duration, and intensity. We assessed whether characteristics of abdominal pain episodes are determinants of clinically relevant improvement of health status after cholecystectomy. Methods:  In a post hoc analysis of a prospective multicenter cohort study, patients of ≥18 years of age with uncomplicated symptomatic cholecystolithiasis subjected to cholecystectomy were included. Preoperatively, patients received a structured interview and a questionnaire consisting of the visual analogue scale (VAS; range 0-100) and gastrointestinal quality of life index (GIQLI). At 12 weeks after cholecystectomy, the GIQLI was again administered. Logistic regression analyses were performed to determine significant associations. Results:  Questionnaires were sent to 261 and returned by 166 (63.6 %) patients (128 females, mean age at surgery 49.5 ± 13.8). A total of 131 (78.9 %) patients reported a clinically relevant improvement of health status. The median (interquartile range) frequency, duration, and intensity of abdominal pain episodes were 0.38 (0.18-0.75) a week, 4.00 (2.00-8.00) hours, and 92 (77-99), respectively. None of the characteristics was associated with a clinically relevant improvement of health status at 12 weeks after cholecystectomy. Conclusions:  Characteristics of abdominal pain episodes cannot be used to inform patients with symptomatic cholecystolithiasis who are skeptic about the timing of cholecystectomy for optimal benefit. Timing of cholecystectomy should therefore be based on other characteristics and preferences

Modelling of Runaway Electron Dynamics in Tokamak Disruptions

International audience• Introduction: disruptions, Runaway Electrons (REs)• Simulation tools• Validation• Simulations for ITER− RE generation (avoidance)− RE beam termination (mitigation)• Conclusio

Persistent and de novo symptoms after cholecystectomy: a systematic review of cholecystectomy effectiveness

Contains fulltext : 117405.pdf (publisher's version ) (Closed access)BACKGROUND: Cholecystectomy is the preferred treatment option for symptomatic gallstones, but the exact relationship between cholecystectomies and symptoms still is unclear. This study aimed to assess the effectiveness of elective cholecystectomy for patients with cholecystolithiasis in terms of both persistent and de novo symptoms. METHODS: A systematic literature search was conducted in Pubmed and Embase. The search included studies comprising patients 18 years of age or older undergoing elective cholecystectomy for symptomatic cholecystolithiasis. The proportions of symptoms after cholecystectomy were calculated and then subdivided into persistent and de novo symptoms. RESULTS: A total of 38 studies reported the presence of postcholecystectomy symptoms. The results showed that upper abdominal pain, the main indication for cholecystectomy in the majority of the patients, mostly disappeared after surgery. However, it persisted in up to 33 % of the patients and arose de novo in up to 14 %. Diarrhea (85 %) and constipation (76 %) were the persistent symptoms most often reported, whereas upper abdominal pain and vomiting were the least often reported. Flatulence (62 %) was the most often reported new symptom. However, large variations in symptoms were found between studies. CONCLUSIONS: The review indicates that cholecystectomy often is ineffective with regard to persistent and de novo symptoms. The finding that the types and proportions of persistent symptoms differ from those that arise de novo suggests that this distinction may be useful in predicting which patients would and which would not benefit from a cholecystectomy