Learning curve for laparoscopic cholecystectomy has not been defined: A systematic review

Background: Laparoscopic cholecystectomy is one of the most performed surgeries worldwide but its learning curve is still unclear. Methods: A systematic review was conducted according to the 2009 Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Two independent reviewers searched the literature in a systematic manner through online databases, including Medline, Scopus, Embase, and Google Scholar. Human studies investigating the learning curve of laparoscopic cholecystectomy were included. The Newcastle–Ottawa scale for cohort studies and the GRADE scale were used for the quality assessment of the selected articles. Results: Nine cohort studies published between 1991 and 2020 were included. All studies showed a great heterogeneity among the considered variables. Seven articles (77.7%) assessed intraoperative variables only, without considering patient's characteristics, operator's experience, and grade of gallbladder inflammation. Only five articles (55%) provided a precise cut-off value to see proficiency in the learning curve, ranging from 13 to 200 laparoscopic cholecystectomies. Conclusions: The lack of clear guidelines when evaluating the learning curve in surgery, probably contributed to the divergent data and heterogeneous results among the studies. The development of guidelines for the investigation and reporting of a surgical learning curve would be helpful to obtain more objective and reliable data especially for common operation such as laparoscopic cholecystectomy

Impact of maritime traffic on polycyclic aromatic hydrocarbons, metals and particulate matter in Venice air

Harbours are important hubs for economic growth in both tourism and commercial activities. They are also an environmental burden being a source of atmospheric pollution often localized near cities and industrial complexes. The aim of this study is to quantify the relative contribution of maritime traffic and harbour activities to atmospheric pollutant concentration in the Venice lagoon. The impact of ship traffic was quantified on various pollutants that are not directly included in the current European legislation for shipping emission reduction: (i) gaseous and particulate PAHs; (ii) metals in PM10; and (iii) PM10 and PM2.5. All contributions were correlated with the tonnage of ships during the sampling periods and results were used to evaluate the impact of the European Directive 2005/33/EC on air quality in Venice comparing measurements taken before and after the application of the Directive (year 2010). The outcomes suggest that legislation on ship traffic, which focused on the issue of the emissions of sulphur oxides, could be an efficient method also to reduce the impact of shipping on primary particulate matter concentration; on the other hand, we did not observe a significant reduction in the contribution of ship traffic and harbour activities to particulate PAHs and metals

Progress and perspectives in the low-energy kaon-nucleon/nuclei interaction studies at the DAΦNE collider

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Cost evaluation of EHVAC offshore wind farm interconnections using intermediate shunt compensation: A parametric study

A double-circuit line using commercially available 400 kV-50 Hz three-core XLPE-insulated submarine cables is considered for the evacuation of up to 1 GW offshore wind generation. Three transmission distances are studied, namely 80 km, 100 km and 160 km, evaluating conventional (line-end) as well as mid-line shunt compensation. Operating envelopes and transmission losses are assessed, showing the low losses at EHVAC cable transmission and the beneficial effects of midline compensation, which allows covering distances up to 180 km. Results show that the proposed transmission solution guarantees very low full-load losses, not exceeding 1.5%, 2% and 3% for the simulated cases. Lastly, a technical-economic comparison based on Dutch North Sea wind producibility data and new German feed-in tariffs, is subsequently carried out in order to assess the capitalized losses of the different EHVAC solutions

Collegamenti in cavo sottomarino nel Mar Mediterraneo: Aspetti tecnologici e di sistema

Il crescente interesse nelle interconnessioni tra stati e nelle centrali eoliche offshore ha portato a significativi miglioramenti nella tecnologia dei cavi sottomarini ad alta tensione. L’articolo tratta le caratteristiche tecnologiche e le problematiche di sistema tipiche dei collegamenti elettrico sottomarini nel mare Mediterraneo, esaminando i recenti sviluppi tecnologici nei convertitori HVDC e nei cavi sottomarini. Viene inoltre discusso lo stato dell’arte della tecnologia per le connessioni sottomarine e vengono presentati le principali problematiche relative alle connessioni sia in corrente alternata, sia in corrente continua, tenendo in conto i recenti sviluppi delle de tecnologie come ad esempio lo sviluppo di cavi tripolari isolati in XLPE di grande sezione. La massima lunghezza e potenza trasmissibile per collegamenti in corrente alternata sono discussi in dettaglio, così come una stima delle perdite per i sistemi HVDC ed HVAC , al fine di valutare la convenienza dell’una o dell’altra soluzione per un dato progetto. Più in particolare è stato esaminato l’effetto del profilo di corrente e potenza reattiva sui cavi in c.a.The growing interest in international interconnection lines as well as offshore-located energy generation has led to the improvement of high voltage submarine transmission technology. The paper deals with the technology and system challenges typical of submarine cable links in the Mediterranean Sea. Recent developments in HVDC converters technology and submarine cables are summarized. An overview of the state-of-the-art for submarine transmission technology is provided and major issues concerning DC and AC connections, taking into account both HVDC-VSC and recent AC advances, such as large cross-section, XLPE-insulated three-core cables are outlined. Attention is focused on the assessment of actual limits of transmissible power and length of AC links and calculation of losses in HVDC and HVAC systems, aiming at the evaluation of the most convenient choice. In particular, the effect of non-uniform reactive power and current profiles along AC cables is studied