A stochastic framework for uncertainty analysis in electric power transmission systems with wind generation

International audienceThe purpose of this work is the analysis of the uncertainties affecting an electric transmission network with wind power generation and their impact on its reliability. A stochastic model was developed to simulate the operations and the line disconnection and reconnection events of the electric network due to overloads beyond the rated capacity. We represent and propagate the uncertainties related to consumption variability, ambient temperature variability, wind speed variability and wind power generation variability. The model is applied to a case study of literature. Conclusions are drawn on the impact that different sources of variability have on the reliability of the network and on the seamless electric power supply. Finally, the analysis enables identifying possible system states, in terms of power request and supply, that are critical for network vulnerability and may induce a cascade of line disconnections leading to massive network blackout

Optimizing protections against cascades in network systems: A modified binary differential evolution algorithm

International audienceThis paper addresses the optimization of protection strategies in critical infrastructures within a complex network systems perspective. The focus is on cascading failures triggered by the intentional removal of a single network component. Three different protection strategies are proposed that minimize the consequences of cascading failures on the entire system, on predetermined areas or on both scales of protective intervention in a multi-objective optimization framework. We optimize the three protection strategies by devising a modified binary differential evolution scheme that overcomes the combinatorial complexity of this optimization problem. We exemplify our methodology with reference to the topology of an electricity infrastructure, i.e. the 380 kV Italian power transmission network. We only focus on the structure of this network as a test case for the suggested protection strategies, with no further reference on its physical and electrical properties

A Multi-Objective Memetic Optimization Method for Power Network Cascading Failures Protection

International audienceReliable and safe power grid operation requires the anticipation of cascading failures and the establishment of appropriate protection plans for their management. In this paper, we address this latter problem by line switching and propose a multi-objective memetic algorithm (MOMA), which combines the binary differential evolution algorithm with the non-dominated sorting mechanism and the Lamarckian local search. The 380 kV Italian power transmission network is used as a realistic test case

Experienţa clinicii de urologie din Târgu-Mureș în tratamentul calculului coralifor

Abstract Percutaneous surgery is a safe and efficient method in the treatment of staghorn calculi. The analysis of our experience in the percutaneous treatment of staghorn calculi over a period of 18 years (1988-2005). During this time practically we have performed open surgery only in a few patient with renal and upper ureteral calculi. From a number of over 6230 patients with renal and upper ureteral calculi treated with the endoscopic method, during the period between 1988-2005, we have performed percutaneous surgery on 1074 patients with staghorn calculi (7 of them were children; 22 patients had bilateral staghorn calculus). The average surgery time was 115 minutes, the average postsurgery hospital care time was 17,5 days. The postoperative “stone free" rate was 914/1074 (85,10%). In 101/1074 (9,40%) cases our patients developed complications and in 3/1074 (0,27%) cases the patient deceased due to hemorrhage and toxico-septic shock. For the successfully treatment of a patient with staghorn calculus using the percutaneous technique it is necessary a good knowledge of the 3D anatomy of the kidney well chosen and correctly executed percutaneous nephrostomy tracks, training, experience and good technical skills in the endourology of the upper urinary tract. Chirurgia percutanată este o metodă sigură şi eficientă în tratamentul litiazei coraliforme. Introducere. Analiza experienţei noastre în tratamentul percutanat al litiazei coraliforme într-o perioadă de 18 ani (1988-2005), în care nu am mai operat deschis, decât un număr foarte mic de pacienţi cu litiază renală şi ureterală superioară. Materiale şi metode. Într-o serie de peste 6230 de pacienţi cu litiază renală şi ureterală superioară rezolvaţi percutanat în intervalul 1988-2005, am operat percutanat 1074 pacienţi cu litiază coraliformă (7 au fost copii; 22 pacienţi au avut litiază coraliformă bilaterală). Rezultate. Timpul operator a fost în medie de 115 minute, durata medie a spitalizării postoperatorii de 17,5 zile. Rata “stone free” postoperator a fost de 914/1074 (85,10%). Am avut complicaţii la 101/1074 (9,40%) pacienţi şi 3/1074 (0,27%) decese prin hemoragie şi şoc toxico-septic. Concluzii. Pentru rezolvarea percutanată cu succes a unui calcul coraliform este necesară o bună cunoaştere a anatomiei tridim ensionale a rinichiului, traiecte de nefrostom ie percutanată bine alese şi corect efectuate, antrenament, experienţă şi o bună tehnicitate în endourologia aparatului urinar superior

Cistita necrotică - dificultăţi diagnostice şi terapeutice

Abstract Necrotic cystitis, also called incrustation cystitis, raises etiopathological and therapeutical problems, with relapse of the necrosis after removal of pathological tissue. Between 01.01.1999 and 31.12.2005 there have been 55 patients institutionalized in our Clinic, presenting lower urinary tract symptoms (LUTS). Instrumental investigations have demonstrated the thickening of the bladder wall, more frequently in the trigonum area. Ultrasound examination and cystography couldn’t exclude an infiltrative bladder tumor. Cystoscopy which showed necrotic bladder tissue, with calcareous incrustations, followed by the resection of the pathologic tissue. In 45 cases the histopathological result was necrotic cystitis and in 10 cases infiltrative urothelial bladder tumor or epidermoid metaplasia. In order to clarify the etiology of the necrosis an investigation protocol have been used, consisting of laboratory tests for autoimmune diseases, vascular or local causes that initiate the necrosis (previous surgery in the area, endoscopic interventions). In 5 cases with autoimmune disease, the treatment was transurethral resection and plasmapheresis. The evolution was favorable in 4 cases. Failure: 1 patient. In 12 cases the cause of the necrosis appears to be a diabetic vasculitis, judging by the deep necrosis, dispersed over several small areas. The posttherapeutic evolution depends on the correct treatment of diabetes. In 10 patients with previous endoscopic surgery, the necrosis has been induced by inadequate electrical currents or mechanical lesions. In 18 patients the causing factor remained unknown. The limited necrosis of the bladder can be caused by autoimmune diseases, vascular diseases (diabetes) and endo-urethral maneuvers. The endoscopic resection of the necrotic bladder wall to the healthy, well vascularised tissue beneath is an important therapeutic procedure. The treatment of the causing factors (autoimmune, vascular) will consolidate the healing. Not knowing the other causes will lead to failure, and repeated endoscopic treatment will result in short term ameliorations. Introducere. Cistita necrotică, denumită în literatură şi “cistita de incrustaţie”, ridică probleme de etiopatogenie, prezentând dificultăţi terapeutice, cu recidiva necrozei după îndepărtarea ţesuturilor patologice. Materiale şi metode. Între 01.01.1999-31.12.2005 au fost internaţi în clinica noastră 55 de pacienţi cu fenomene urinare joase de tip iritativ. Investigaţiile paraclinice au pus în evidenţă peretele vezical îngroşat, situaţie frecventă în trigon. Ecografia şi cistografia nu puteau exclude aspectul unei tumori vezicale infiltrative.Cistoscopia a evidenţiat un ţesut vezical necrozat, cu incrustaţii calcare, fiind urmată de rezecţia ţesutului patologic. La 45 de pacienţi rezultatul histopatologic a fost de cistită necrotică, iar la 10 bolnavi s-a depistat tumoră vezicală urotelială infiltrativă sau metaplazie epidermoidă. Pentru a elucida etiopatogenia necrozei, s-a aplicat un protocol de investigare care include teste de laborator pentru depistarea unui proces autoimun, a unor cauze vasculare sau a unor cauze locale de declanşare a necrozei (intervenţii în antecedente, manevre endoscopice, etc.). Rezultate şi discuţii. La 5 bolnavi cu proces autoimun, tratamentul a constat din rezecţie transuretrală şi din plasmafereză. Evoluţie favorabilă, cu vindecare - la 4 bolnavi. Eşec: 1 pacientă. La 12 bolnavi cauza necrozei este sugerată a fi o vasculită diabetică, după aspectul profund al necrozei în puncte dispersate, evoluţia postterapeutică este influenţată de tratamentul corect al diabetului. La 10 pacienţi cu manevre chirurgicale endoscopice în antecedente, inducţia procesului necrotic a fost provocat de curenţi electrici inadecuaţi sau de leziuni mecanice. La 18 bolnavi cauza a fost necunoscută. Concluzii. Necroza limitată a vezicii urinare poate avea cauze autoimune, vasculare (diabet), manevre endouretrale. Rezecţia endoscopică a peretelui vezical necrozat până în ţesut bine vascularizat este un gest terapeutic important. Tratamentul cauzal (autoimun, vascular, etc.) consolidează vindecarea. Necunoaşterea şi a altor cauze duce la eşec, iar tratamentul endoscopic repetat - la ameliorări pasagere

Electrochemical evaluation of dsDNA—Liposomes interactions

The aim of the present work was to evaluate the interaction between double-stranded DNA (dsDNA) and liposomes by voltammetric methods. The experimental results were analyzed considering the initial studies regarding the oxidation mechanism of dsDNA purine bases by cyclic and differential pulse voltammetry at the glassy carbon electrode (GCE). The interaction between dsDNA and 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) was studied in a suspension containing both dsDNA and DMPC liposomes, prepared in pH = 7.0, 0.1 M phosphate buffer and using different incubation time periods. The formation of dsDNA-liposome complex was put in evidence by the decrease of the dsDNA oxidation peaks, dependent upon the incubation time. This behavior was explained considering the electroactive centers of dsDNA, guanosine monophosphate and adenosine monophosphate residues, part of them hidden inside the dsDNA-liposome complex structure and thus being unable to reach the GC electrode and preventing their oxidation. The electrochemical results are relevant for a better physicochemical characterisation of the dsDNA and dsDNA-liposome complex, which can be important for the development of gene therapy vectors

The emergency department arrival mode and its relations to ED management and 30-day mortality in acute heart failure: an ancillary analysis from the EURODEM study

Background Acute heart failure patients are often encountered in emergency departments (ED) from 11% to 57% using emergency medical services (EMS). Our aim was to evaluate the association of EMS use with acute heart failure patients' ED management and short-term outcomes. Methods This was a sub-analysis of a European EURODEM study. Data on patients presenting with dyspnoea were collected prospectively from European EDs. Patients with ED diagnosis of acute heart failure were categorized into two groups: those using EMS and those self-presenting (non- EMS). The independent association between EMS use and 30-day mortality was evaluated with logistic regression. Results Of the 500 acute heart failure patients, with information about the arrival mode to the ED, 309 (61.8%) arrived by EMS. These patients were older (median age 80 vs. 75 years, p 30/min in 17.1% patients vs. 7.5%, p = 0.005). The only difference in ED management appeared in the use of ventilatory support: 78.3% of EMS patients vs. 67.5% of non- EMS patients received supplementary oxygen (p = 0.007), and non-invasive ventilation was administered to 12.5% of EMS patients vs. 4.2% non- EMS patients (p = 0.002). EMS patients were more often hospitalized (82.4% vs. 65.9%, p < 0.001), had higher in-hospital mortality (8.7% vs. 3.1%, p = 0.014) and 30-day mortality (14.3% vs. 4.9%, p < 0.001). The use of EMS was an independent predictor of 30-day mortality (OR = 2.54, 95% CI 1.11-5.81, p = 0.027). Conclusion Most acute heart failure patients arrive at ED by EMS. These patients suffer from more severe respiratory distress and receive more often ventilatory support. EMS use is an independent predictor of 30-day mortality

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10&nbsp;years; 78.2% included were male with a median age of 37&nbsp;years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020