An overview of the current research on stability of ships and ocean vehicles : the STAB2018 perspective

The paper provides an insight into contemporary research on ship stability and identifies the possible directions for future research by reviewing a selection of papers published in STAB 2015, ISSW 2016 & 2017. These works have been organized in different sections, according to the main thematic areas of research, covering intact and damage stability, regulatory issues including probabilistic approaches, advanced numerical methods for ship motion and stability failure prediction including roll damping, operational issues related to ship stability and environmental modelling. Furthermore, the educational potential of STAB/ISSW is exemplified. This review paper is a joint effort within the SRDC (Stability R&D Committee)

Réponses extrêmes et fatigue dues aux chargements globaux de houle

Le juste dimensionnement des structures navales passe la connaissance précise des efforts qu’elles auront à supporter. Ainsi par exemple, concernant les chargements d’origine hydrodynamique, des valeurs extrêmes atteintes expérimentalement ou tirées de calculs déterministes sont préférées aux valeurs règlementaires de conception. Le Bassin d’essais des carènes participe à cet axe de progrès. Le présent article expose les derniers travaux réalisés par le Bassin en la matière

OMAE2008-57326 LONG-TERM NON-LINEAR BENDING MOMENT PREDICTION

ABSTRACT Long-term analysis is more and more used to establish the design loads by performing direct loads evaluation. The longterm distribution of wave loads acting on a ship depends on the short-term contributions of the response in all the wave conditions the ship encounters in her life: sea state, relative heading, speed, load case… For each short-term condition the statistical parameters that describe the response are considered to be constant. Therefore a long-term analysis needs a correct evaluation of the short-term parameters that characterise the short-term response. The Weibull distribution is often used to model the extreme response on a given sea state. The precision of the long-term analysis depends directly on the precision of the Weibull parameters. The first part of this paper is a study of the influence of the simulations parameters (number of wave components, simulation time) and of the different methods used to fit a Weibull distribution on the bending moment extremes, on the precision of the Weibull parameters and on the extreme values. Every choice of parameter used for the final calculations will be justified. The conclusion is that by using a correct fitting method, and provided that there are at least 128 wave components, the overall precision is only dependent on the simulation time : the precision on the 10 -5 extreme value is only ±6.4% with 400 extremes, and ±1.9% with 3200 extremes ! In order to increase the precision of the evaluation of the Weibull parameters over the entire scatter diagram, without increasing the simulation time, a smoothing method is proposed, based on a polynomial smoothing of the A 1/3 and A 1/10 values obtained from linear and non linear calculations on the same wave signal, and on the method of moments. This method leads to an increase of precision of about 3 times, that is equivalent to increase the simulation time by 8 or 9! The second part of this paper presents the results of the long-term analysis carried out on 14 ships (ferries, container vessel, naval ships,…), using a non-linear sea-keeping timedomain software. Calculations have been done without forward speed in head waves and for all the sea states of the IACS scatter diagram (more than 200 sea states). The smoothing method has been used to compute all the Weibull coefficients. Results show that it is possible to model the non-linear effects by applying a non-linear coefficient on the linear bending moment for one speed, one scatter diagram and one extreme value probability. But this coefficient can't be applied, and must be recalculated, if other cases are needed (other speed, other scatter diagram, relative heading distribution or other extreme value probabilities). Every ships will be compared in the same graph in order to evaluated the influence of the design hull form (as overall length and bow flare) on the non linear long term bending moments value (in hogging and in sagging). The calculations were focused on the case of a particular frigate where more parameters were studied as forward speed, operational profile (in speed and relative headings) and scatter diagram choice. In the third part results from model test performed on a height segmented model of the frigate will be compared to the short term results computed by the sea-keeping software. This frigate has been monitored for three years, and the strain measurements at sea will be compared to the numerical longterm analysis

Role of biomarkers in the management of antibiotic therapy: an expert panel review II: clinical use of biomarkers for initiation or discontinuation of antibiotic therapy.

EA MERSInternational audienceBiomarker-guided initiation of antibiotic therapy has been studied in four conditions: acute pancreatitis, lower respiratory tract infection (LRTI), meningitis, and sepsis in the ICU. In pancreatitis with suspected infected necrosis, initiating antibiotics best relies on fine-needle aspiration and demonstration of infected material. We suggest that PCT be measured to help predict infection; however, available data are insufficient to decide on initiating antibiotics based on PCT levels. In adult patients suspected of community-acquired LRTI, we suggest withholding antibiotic therapy when the serum PCT level is low (=0.5 ng/mL also may be used, but false-negatives may occur. In adults with suspected bacterial meningitis, we suggest integrating serum PCT measurements in a clinical decision rule to help distinguish between viral and bacterial meningitis, using a 0.5 ng/mL threshold. For ICU patients suspected of community-acquired infection, we do not recommend using a threshold serum PCT value to help the decision to initiate antibiotic therapy; data are insufficient to recommend using PCT serum kinetics for the decision to initiate antibiotic therapy in patients suspected of ICU-acquired infection. In children, CRP can probably be used to help discontinue therapy, although the evidence is limited. In adults, antibiotic discontinuation can be based on an algorithm using repeated PCT measurements. In non-immunocompromised out- or in- patients treated for RTI, antibiotics can be discontinued if the PCT level at day 3 is 80-90%, whether or not microbiological documentation has been obtained. For ICU patients who have nonbacteremic sepsis from a known site of infection, antibiotics can be stopped if the PCT level at day 3 is 80% relative to the highest level recorded, irrespective of the severity of the infectious episode; in bacteremic patients, a minimal duration of therapy of 5 days is recommended

An overview of the current research on stability of ships and ocean vehicles

The paper analyses the state-of-the-art and future perspectives by reviewing a selection of papers published in STAB2015, ISSW2016 & 2017. These works have been organized in different sections, according to the main thematic areas of research, covering intact and damage stability, regulatory issues including probabilistic approaches, advanced numerical methods for ship motion and stability failure prediction including roll damping, operational issues related to ship stability and environmental modelling. Furthermore, the challenges of feeding back to the educational process the research conducted are discussed. This review paper is a joint effort within the SRDC (Stability R&D Committee)

Characterization of rainbow trout gonad, brain and gill deep cDNA repertoires using a Roche 454-Titanium sequencing approach

Rainbow trout, Oncorhynchus mykiss, is an important aquaculture species worldwide and, in addition to being of commercial interest, it is also a research model organism of considerable scientific importance. Because of the lack of a whole genome sequence in that species, transcriptomic analyses of this species have often been hindered. Using next-generation sequencing (NGS) technologies, we sought to fill these informational gaps. Here, using Roche 454-Titanium technology, we provide new tissue-specific cDNA repertoires from several rainbow trout tissues. Non-normalized cDNA libraries were constructed from testis, ovary, brain and gill rainbow trout tissue samples, and these different libraries were sequenced in 10 separate half-runs of 454-Titanium. Overall, we produced a total of 3 million quality sequences with an average size of 328 bp, representing more than 1 Gb of expressed sequence information. These sequences have been combined with all publicly available rainbow trout sequences, resulting in a total of 242,187 clusters of putative transcript groups and 22,373 singletons. To identify the predominantly expressed genes in different tissues of interest, we developed a Digital Differential Display (DDD) approach. This approach allowed us to characterize the genes that are predominantly expressed within each tissue of interest. Of these genes, some were already known to be tissue-specific, thereby validating our approach. Many others, however, were novel candidates, demonstrating the usefulness of our strategy and of such tissue-specific resources. This new sequence information, acquired using NGS 454-Titanium technology, deeply enriched our current knowledge of the expressed genes in rainbow trout through the identification of an increased number of tissue-specific sequences. This identification allowed a precise cDNA tissue repertoire to be characterized in several important rainbow trout tissues. The rainbow trout contig browser can be accessed at the following publicly available web site (http://www.sigenae.org/)

Impact of integrating objective structured clinical examination into academic student assessment: Large-scale experience in a French medical school

International audiencePurpose: Objective structured clinical examinations (OSCE) evaluate clinical reasoning, communication skills, and interpersonal behavior during medical education. In France, clinical training has long relied on bedside clinical practice in academic hospitals. The need for a simulated teaching environment has recently emerged, due to the increasing number of students admitted to medical schools, and the necessity of objectively evaluating practical skills. This study aimed at investigating the relationships between OSCE grades and current evaluation modalities.Methods: Three-hundred seventy-nine 4th-year students of University-of-Paris Medical School participated to the first large-scale OSCE at this institution, consisting in three OSCE stations (OSCE#1–3). OSCE#1 and #2 focused on cardiovascular clinical skills and competence, whereas OSCE#3 focused on relational skills while providing explanations before planned cholecystectomy. We investigated correlations of OSCE grades with multiple choice (MCQ)-based written examinations and evaluations of clinical skills and behavior (during hospital traineeships); OSCE grade distribution; and the impact of integrating OSCE grades into the current evaluation in terms of student ranking.Results: The competence-oriented OSCE#1 and OSCE#2 grades correlated only with MCQ grades (r = 0.19, P0.75). Conversely, the behavior-oriented OSCE#3 grades correlated with traineeship skill and behavior grades (r = 0.19, P<0.001, and r = 0.12, P = 0.032), but not with MCQ grades (P = 0.09). The dispersion of OSCE grades was wider than for MCQ examinations (P<0.001). When OSCE grades were integrated to the final fourth-year grade with an incremental 10%, 20% or 40% coefficient, an increasing proportion of the 379 students had a ranking variation by ±50 ranks (P<0.001). This ranking change mainly affected students among the mid-50% of ranking.Conclusion: This large-scale French experience showed that OSCE designed to assess a combination of clinical competence and behavioral skills, increases the discriminatory capacity of current evaluations modalities in French medical schools

Mechanical Thrombectomy for Acute Ischemic Stroke Amid the COVID-19 Outbreak

International audienceBackground and Purpose: The efficiency of prehospital care chain response and the adequacy of hospital resources are challenged amid the coronavirus disease 2019 (COVID-19) outbreak, with suspected consequences for patients with ischemic stroke eligible for mechanical thrombectomy (MT). Methods: We conducted a prospective national-level data collection of patients treated with MT, ranging 45 days across epidemic containment measures instatement, and of patients treated during the same calendar period in 2019. The primary end point was the variation of patients receiving MT during the epidemic period. Secondary end points included care delays between onset, imaging, and groin puncture. To analyze the primary end point, we used a Poisson regression model. We then analyzed the correlation between the number of MTs and the number of COVID-19 cases hospitalizations, using the Pearson correlation coefficient (compared with the null value). Results: A total of 1513 patients were included at 32 centers, in all French administrative regions. There was a 21% significant decrease (0.79; [95%CI, 0.76–0.82]; P <0.001) in MT case volumes during the epidemic period, and a significant increase in delays between imaging and groin puncture, overall (mean 144.9±SD 86.8 minutes versus 126.2±70.9; P <0.001 in 2019) and in transferred patients (mean 182.6±SD 82.0 minutes versus 153.25±67; P <0.001). After the instatement of strict epidemic mitigation measures, there was a significant negative correlation between the number of hospitalizations for COVID and the number of MT cases ( R 2 −0.51; P =0.04). Patients treated during the COVID outbreak were less likely to receive intravenous thrombolysis and to have unwitnessed strokes (both P <0.05). Conclusions: Our study showed a significant decrease in patients treated with MTs during the first stages of the COVID epidemic in France and alarming indicators of lengthened care delays. These findings prompt immediate consideration of local and regional stroke networks preparedness in the varying contexts of COVID-19 pandemic evolution

Thrombectomy complications in large vessel occlusions: Incidence, predictors, and clinical impact in the ETIS registry

International audienceBACKGROUND AND PURPOSE: Procedural complications in thrombectomy for large vessel occlusions of the anterior circulation are not well described. We investigated the incidence, risk factors, and clinical implications of thrombectomy complications in daily clinical practice. METHODS: We used data from the ongoing prospective multicenter observational Endovascular Treatment in Ischemic Stroke Registry in France. The present study is a retrospective analysis of 4029 stroke patients with anterior large vessel occlusions treated with thrombectomy between January 2015 and May 2020 in 18 centers. We systematically collected procedural data, incidence of embolic complications, perforations and dissections, clinical outcome at 90 days, and hemorrhagic complications. RESULTS: Procedural complications occurred in 7.99% (95% CI, 7.17%–8.87%), and embolus to a new territory (ENT) was the most frequent (5.2%). Predictors of ENTs were terminal carotid/tandem occlusion (odds ratio [OR], 5 [95% CI, 2.03–12.31]; P<0.001) and an increased total number of passes (OR, 1.22 [95% CI, 1.05–1.41]; P=0.006). ENTs were associated to worse clinical outcomes (90-day modified Rankin Scale score, 0–2; adjusted OR, 0.4 [95% CI, 0.25–0.63]; P<0.001), increased mortality (adjusted OR, 1.74 [95% CI, 1.2–2.53]; P<0.001), and symptomatic intracerebral hemorrhage (adjusted OR, 1.87 [95% CI, 1.15–3.03]; P=0.011). Perforations occurred in 1.69% (95% CI, 1.31%–2.13%). Predictors of perforations were terminal carotid/tandem occlusions (39.7% versus 27.6%; P=0.028). 40.7% of patients died at 90 days, and the overall rate of poor outcome was 74.6% in case of perforation. Dissections occurred in 1.46% (95% CI, 1.11%–1.88%) and were more common in younger patients (median age, 64.2 versus 70.2 years; P=0.002). Dissections did not affect the clinical outcome at 90 days. Besides dissection, complications were independent of the thrombectomy technique. CONCLUSIONS: Thrombectomy complication rate is not negligible, and ENTs were the most frequent. ENTs and perforations were associated with disability and mortality, and terminal carotid/tandem occlusions were a risk factor