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Analysis, Synthesis and Implementation of a Direct Current Control Strategy for Three-Phase Grid Connected Converter
No full textInternational audienceThis work presents the analysis, synthesis and implementation of a direct current control strategy for a three- phase Grid connected Converter (GcC). The considered control strategy is aimed to control the grid current vector in the d-q reference frame. For that, two switching functions linked to the d-q components of the grid current vector were defined. These switching functions were utilized to deduce rules that allow an appropriate selection of the GcC voltage vector for the control of the grid current vector components during full and low loads, during transients and steady-state operation. In order to show the performances of the developed control strategy, simulation tests were carried out and compared with the results of two direct current control strategies: A three-Hysteresis Controllers (3HC), and a two- Hysteresis Controllers using six-Sectors Switching Table (2HC- 6SST). The obtained results confirmed that the proposed control strategy decreases the switching frequency while maintaining a good value of the Total Harmonic Distortion factor (THD) of the grid currents. Also, the DC-link voltage fluctuations during severe and sudden change of the transferred active power are reduced
Determinants of firm liquidity in Central and Eastern Europe SMEs
No full textInternational audienceThis study examines firm-level determinants of liquidity as reflected by the cash conversion cycle for SMEs in Central and Eastern Europe. This study focuses on non-financial SME firms in Central and Eastern Europe. GDP growth was the only macroeconomic variable used in this study and the only variable with insignificant influence on liquidity in regression conducted for the seven countries studied, using the GMM estimation method. The sensitivity of liquidity to explanatory variables (profitability, leverage, tangibility, growth, age, size, and GDP growth) was examined on data composed of 160 publicly-listed SMEs with 1,600 the total number of observations for the period 2011-2019. Profitability, leverage, and size have a positive significant influence on liquidity. The positive significant influence of profitability reflects how SMEs with low levels of liquidity depend on profitability to meet cash requirements for investing in liquidity
Outcomes of Transcatheter Aortic Valve Implantation in Nonagenarians Compared to Younger than 90 Year Old Patients
No full textInternational audienceBackground: Given that life expectancy has improved, nonagenarians have become a significant proportion of world population. As aortic stenosis is primarily a disease of the elderly, the need for invasive cardiac approaches is expected to increase in people of extreme age. Herein, we compare the in-hospital adverse clinical outcomes and mortality after transcatheter aortic valve implantation (TAVI) procedures in nonagenarians to younger than 90 year old patients.Methods: A retrospective study was conducted on 1336 patients who underwent TAVI between January 2016 and March 2020 at Toulouse University Hospital, Rangueil, France. Post-TAVI adverse clinical outcomes were defined according to Valve Academic Research Consortium-2 Criteria. The studied population was divided into 2 groups according to age.Results: Out of 1336 patients, 250 (18.7%) were nonagenarians with a mean age of 91.8 ± 1.9 years. Pacemaker implantation (12.4% vs 12.1%), stroke (2% vs 1.8%), and major vascular complications (9.2% vs 6.7%) were more common in nonagenarians, whereas acute kidney injury (1.2% vs 2.7%) and major bleeding events (3.2% vs 3.4%) were more common in the <90-year-old group. Nonagenarians are more likely to develop major vascular complications (odds ratio [OR] = 1.76 95% confidence interval [CI] 1.04-3, P = .03). The prevalence of in-hospital mortality in nonagenarians and <90-year-old patients were 5.2% and 2%, respectively. Survival analysis showed a significant difference in mortality during hospitalization period only ( P = .04).Conclusion: The prevalence of TAVI procedural success is remarkably high in nonagenarians and comparable to that of younger patients. However, the in-hospital mortality rate was 2-fold more than that of <90-year-old patients
Stent angioplasty for coronary compression syndrome related to prosthetic aortic valve
No full textInternational audienceNo abstract availabl
Parental divorce and nicotine addiction in Lebanese adolescents: the mediating role of child abuse and bullying victimization
No full textInternational audienceBackground: Lebanon ranks first amongst Middle-Eastern countries in terms of cigarette and waterpipe smoking. Understanding the mediating factors for nicotine addiction in adolescents who have experienced parental divorce is vital to take effective measures that will help in lowering its prevalence in our community. The objective of this study was to investigate the association between the increasingly concerning parental divorce and nicotine addiction in Lebanese adolescents while taking into consideration the plausible mediating effect of abuse and bullying victimization.Methods: This was a cross-sectional survey-based study that was conducted between January and May 2019. A total of 1810 adolescents aged between 14 and 17 years was enrolled from 16 Lebanese schools. Linear regressions taking the cigarette and waterpipe dependence scores as dependent variables were conducted respectively, using the SPSS software. PROCESS v3.4 model 4 was used for mediation analysis.Results: A total of 11.9% of the enrolled participants had divorced parents. Higher cigarette and waterpipe dependence were found in adolescents whose parents were divorced compared to those living together. More child psychological abuse, having divorced parents vs living together, and more child physical abuse were significantly associated with higher cigarette dependence. More child psychological and physical, and having divorced parents vs living together were significantly associated with more waterpipe dependence. In addition, all forms of abuse (except neglect) and bullying victimization had a partially mediating effect in the associations between parental divorce and nicotine dependence (cigarette and waterpipe) in adolescents.Conclusion: This study results may serve as a first step towards enrolling separated parents and their children in special prevention programs to help them create a protective and supportive environment
The Detection of Potential Native Probiotics Lactobacillus spp. against Salmonella Enteritidis, Salmonella Infantis and Salmonella Kentucky ST198 of Lebanese Chicken Origin
No full textInternational audienceSalmonella continues to be a major threat to public health, especially with respect to strains from a poultry origin. In recent years, an increasing trend of antimicrobial resistance (AMR) in Salmonella spp. was observed due to the misuse of antibiotics. Among the approaches advised for overcoming AMR, probiotics from the Lactobacillus genus have increasingly been considered for use as effective prophylactic and therapeutic agents belonging to the indigenous microbiota. In this study, we isolated lactobacilli from the ilea and ceca of hens and broilers in order to evaluate their potential probiotic properties. Four species were identified as Limosilactobacillusreuteri (n = 22, 45.8%), Ligilactobacillussalivarius (n = 20, 41.6%), Limosilactobacillus fermentum (n = 2, 4.2%) and Lactobacillus crispatus (n = 1, 2%), while three other isolates (n = 3, 6.25%) were non-typable. Eight isolates, including Ligilactobacillussalivarius (n = 4), Limosilactobacillusreuteri (n = 2), L. crispatus (n = 1) and Lactobacillus spp. (n = 1) were chosen on the basis of their cell surface hydrophobicity and auto/co-aggregation ability for further adhesion assays using the adenocarcinoma cell line Caco-2. The adhesion rate of these strains varied from 0.53 to 10.78%. Ligilactobacillussalivarius A30/i26 and 16/c6 and Limosilactobacillus reuteri 1/c24 showed the highest adhesion capacity, and were assessed for their ability to compete in and exclude the adhesion of Salmonella to the Caco-2 cells. Interestingly, Ligilactobacillussalivarius 16/c6 was shown to significantly exclude the adhesion of the three Salmonella serotypes, S. Enteritidis, S. Infantis and S. Kentucky ST 198, to Caco-2 cells. The results of the liquid co-culture assays revealed a complete inhibition of the growth of Salmonella after 24 h. Consequently, the indigenous Ligilactobacillussalivarius 16/c6 strain shows promising potential for use as a preventive probiotic added directly to the diet for the control of the colonization of Salmonella spp. in poultry
Adaptative Workflows for Process Management
No full textInternational audienceIn industry, modeling is used to enhance productivity, facilitate analysis, and increase profitability. Modeling is used to represent the workflow activities of a prescribed business process operation. But what happens if an unexpected event occurs? This might lead to a deviation of prescribed business operation. In related approaches all solutions are predefined in a way or in another where in other words, most events must be predicted in advance and the others are not caught. This study will introduce a new approach to consider unexpected events occurring in workflow execution. Then, after characterizing the situation, the proposed approach will search a library for compatible solutions to repair the model. Next, the best solutionis selected (automatically or manually) and injected in the workflow with respect to an objective function set by experts. Moreover, the library of models can be open to external contribution and benefits from collaborative works
Physicochemical and Mechanical Properties of Premixed Calcium Silicate and Resin Sealers
No full textInternational audienceThe aim of the present in vitro study was to evaluate specific mechanical and physicochemical properties of two calcium silicate based sealers, (AH Plus Bioceramic “AHPB”; Well-Root ST “WRST”), and a conventional resin sealer (AH Plus “AHP”). These aims were accomplished by assessing the porosity, pH, compression strength, roughness, wettability and cell attachment of the tested materials. The results were compared statistically using the one-way ANOVA test. Higher pH values were obtained in both AHPB and WRST compared to AHP at 3, 24 and 72 h (p < 0.05). A greater level of porosity and wettability was detected for both AHPB and WRST compared to the resin sealer AHP (p < 0.05). Evident cell growth characterized by elongated morphology was observed on the surface of AHPB and WRST, while only a thin layer of cells was seen on the surface of AHP. A significant lower compression strength and modulus were obtained in the specimens created using AHPB compared to those made with AHP and WRST (p < 0.05). The removal of calcium silicates may be quite tricky during endodontic retreatment. In conclusion, considering the limitations of the present in vitro study, both calcium silicate sealers demonstrated good physicochemical properties. However, the lower compression strength and modulus of AHPB may facilitate its removal and make the retreatment procedures considerably easier. Keywords: calcium silicate based sealer; resin sealer; mechanical properties; porosit
Effectiveness of Three Agents in Pulpotomy Treatment of Permanent Molars with Incomplete Root Development: A Randomized Controlled Trial
No full textThe aim of this study was to investigate and compare, radiographically and clinically, the impacts of calcium-silicate based-cement (CSBC), nano-hydroxyapatite and platelet-rich fibrin (PRF) as pulpotomy agents in permanent immature molars with incomplete root development. Sixty-three participants (63 permanent immature molars) were included in this study. The patients were randomly divided into three equal groups. Fast setting MTA (MM-MTA), nano-hydroxyapatite and platelet-rich fibrin were used as pulpotomy agents. The teeth were evaluated clinically and radiographically after 6 and 12 months by two blinded examiners. Apical closure and pulp canal obliteration percentages were recorded. The in vitro reaction of the tested materials after a 7-day immersion period of the different materials in phosphate-buffered solution was analyzed using scanning electron microscopy to associate the in vitro mineralization with in vivo pulp canal obliteration percentages. Data were analyzed using Chi-square and ANOVA tests (α = 0.05). No significant difference was found between the three tested groups in terms of clinical and radiographic success (p > 0.05). All cases demonstrated evidence of root growth, including complete apical closure or continued apical closure. At 12 months, complete apical closure was found among the MM-MTA group (50%), nano-hydroxyapatite group (55%) and platelet-rich fibrin group (60%) (p > 0.05). After 12 months, pulp canal obliteration was more observed in the MM-MTA and nano-hydroxyapatite groups than in the PRF group (p < 0.05). MM-MTA (auto-mixed), NHA (hand-mixed) and PRF (autologous) could be used as pulpotomy agents since they exhibit comparable high clinical and radiographic success rates. However, the fact that the groups managed with MM-MTA and NHA have a higher tendency to canal obliteration might indicate that PRF should be considered the first choice material as pulpotomy agent, as it would make retreatment considerably easier. View Full-Text Keywords: pulpotomy; permanent molars with incomplete root development; MM-MTA; nano-hydroxyapatit