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A posteriori error estimates for the large eddy simulation applied to stationary Navier–Stokes equations
No full textInternational audienceIn this paper, we study in two and three space dimensions, the a posteriori error estimates for the Large Eddy Simulation applied to the Navier-Stokes system. We begin by introducing the Navier-Stokes and the corresponding Large Eddy Simulation (LES) equations. Then we introduce the corresponding discrete problem based on the finite element method. We establish an a posteriori error estimation with three types of error indicators related to the filter of the LES method, to the discretization and to the linearization. Finally, numerical investigations are shown and discussed
Stokes and Navier-Stokes equations under power law slip boundary condition: Numerical Analysis
No full textInternational audienceIn this work, we study theoretically and numerically the equations of Stokes and Navier-Stokes under power law slip boundary condition. We establish existence of a unique solution by using the monotone operators theory for the Stokes equations whereas for the Navier-Stokes equations, we construct the solution by means of Galerkin's approximation combined with some compactness results. Next, we formulate and analyze the finite element approximations associated to these problems. We derive optimal and sub-optimal a priori error estimate for both problems depending how the monotonicity is used. Iterative schemes for solving the nonlinear problems are formulated and convergence is studied. Numerical experiments presented confirm the theoretical findings
Adhesion of Resin to Lithium Disilicate with Different Surface Treatments before and after Salivary Contamination—An In-Vitro Study
No full textThe salivary contamination occurring at the try-in procedures of lithium disilicate (LDS) can jeopardize their bond strength. Various laboratory reports have concluded that applying 37% phosphoric acid (H3PO4) could be considered as a predictable way of removing salivary contaminants. An experimental method that consists of sealing the intaglio of the ceramic restorations with a layer of cured adhesive could allow consequent time saving for dental practitioners. It is, besides, necessary to establish an optimal decontamination protocol. Hence, this study aimed to determine the most efficient surface treatment, before and after salivary contamination, by comparing the adhesion between resin and LDS. In order to do so, five groups of ten specimens (n = 10) each underwent the different types of surface treatments before bonding, followed by 2500 cycles in the thermocycler. A shear bond strength (SBS) test was then conducted on a universal testing machine (YLE GmbH Waldstraße Bad König, Germany), followed by a fracture-type analysis on an optical microscope (Olympus BX53, Shinjuku, Tokyo, Japan). Statistical analysis was set with a level of significance of α = 0.05. The surface treatment significantly affected the SBS results. The decontamination with HF (12.59 ± 2.71 MPa) and H3PO4 (13.11 ± 1.03 MPa) obtained the highest values, silanizing only before contamination obtained intermediate values (11.74 ± 3.49 MPa), and silanizing both before and after the salivary contamination (10.41 ± 2.75 MPa) along with applying a bonding agent before contamination (9.65 ± 1.99 MPa) resulted in the lowest values. In conclusion, H3PO4 proved to be efficient, thus, allowing the practitioner to avoid the clinical use of HF; it can, therefore, be considered as a valid alternative. Presilanization and resilanization of specimens, along with applying a bonding agent before contamination, did not yield satisfying results
Bond Strength of Adhesive Systems to Calcium Silicate-Based Materials: A Systematic Review and Meta-Analysis of In Vitro Studies
No full textSince the adhesion of resin composites to calcium silicate-based cement is considered challenging. Therefore, the best adhesion strategy should be indicated. This review aimed to assess the effect of different adhesive systems on the bond strength of resin composite to calcium silicate-based cement through a systematic review and meta-analysis. The subsequent PICOS framework used was: population, calcium silicate-based cement; intervention, use of self-etch adhesive systems; control, use of total-etch adhesive systems; outcome, bond strength; study design, in vitro studies. The literature search was conducted independently by two reviewers up to 18 February 2021. Electronic databases (PubMed, ISI Web of Science, SciELO, Scopus, and Embase) were searched for applicable articles. In vitro manuscripts studying the effect of adhesive systems on the bond strength of calcium silicate-based cement were considered. The meta-analyses were performed using Review Manager Software version 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). Bond strength comparisons were made considering the type of calcium silicate-based cement (Mineral Trioxide Aggregate (MTA), Biodentine™, or TheraCal LC®). A p-value < 0.05 was considered statistically significant. A total of 7321 studies were retrieved in databases searched. After full-text evaluation, 37 eligible papers were assessed for qualitative analysis, leaving a total of 22 papers for the quantitative analysis. According to the meta-analysis, the bond strength values of resin composite materials to MTA and TheraCal LC® cement were favored when a total-etch adhesive system was used (p ≤ 0.02). On the other hand, the meta-analysis of the bond strength of resin-based materials to Biodentine™ calcium silicate-based cement was similar between both approaches (p = 0.12). The in vitro evidence suggests that the bond strength of resin-based materials to both MTA and TheraCal LC® cement was preferred by using the total-etch adhesive strategy. However, when bonding to Biodentine™, the use of self-etch or total-etch strategies displayed promising results. Given the lack of evidence related to the chemical interaction of self-etch adhesive materials with the bioceramics, if self-etch adhesives are used for bonding resin-based restorations to calcium silicate-based cement, a pretreatment with phosphoric acid could be recommended
Experimental cross sections for water ionization due to the impact of light ions—A review
No full textInternational audienceThis work is a short review on the experimental cross sections for water ionization due to the impact of light ions (Z ≤ 6), including related processes such as electron capture and water molecule fragmentation. These cross sections are crucial in studies dealing with the biological effects produced by the impact of ions on living beings. Physical interpretations of the experimental results are also provided
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
Seismic and air monitoring observatory for greater Beirut : a citizen observatory of the "urban health" of Beirut
No full textInternational audienceAlready sensitive because of its geology (seismic-tsunamic risk) and its interface between arid and temperate ecosystems, the Mediterranean Basin is being transformed by climate change and major urban pressure on resources and spaces. Lebanon concentrates on a small territory the environmental, climatic, health, social and political crises of the Middle East: shortages and degradation of surface and groundwater quality, air pollution, landscape fragmentation, destruction of ecosystems, erosion of biodiversity, telluric risks and very few mechanisms of information, prevention and protection against these vulnerabilities. Further, Lebanon is sorely lacking in environmental data at sufficient temporal and spatial scales to cover the range of key phenomena and to allow the integration of environmental issues for the country's development. This absence was sadly illustrated during the August 4th, 2020, explosion at the port of Beirut, which hindered the effective management of induced threats to protect the inhabitants. In this degraded context combined with a systemic crisis situation in Lebanon, frugal innovation is more than an option, it is a necessity. Initiated in 2021 within the framework of the O-LIFE lebanese-french research consortium (www.o-life.org), the « Seismic and air monitoring observatory for greater Beirut » (SMOAG) project aims at setting up a citizen observatory of the urban health of Beirut by deploying innovative, connected, low-cost, energy-efficient and robust environmental and seismological instruments. Through co-constructed web services and mobile applications with various stakeholders (citizens, NGOs, decision makers and scientists), the SMOAG citizen observatory will contribute to the information and mobilization of Lebanese citizens and managers by sharing the monitoring of key indicators associated with air quality, heat islands and building stability, essential issues for a sustainable Beirut.The first phase of the project was dedicated to the development of a low-cost environmental sensor enabling pollution and urban weather measurements (particle matters, SO2, CO, O3, N02, solar radiation, wind speed, temperature, humidity, rainfall) and to the development of all the software infrastructure, from data acquisition to the synoptic indicators accessible via web and mobile application, while following the standards of the Sensor Web Enablement and Sensor Observation System of the OGC and to the FAIR principles (Easy to find, Accessible, Interoperable, Reusable). A website and Android/IOS applications for the restitution of data and indicators and a dashboard allowing real time access to data have been developed. Environmental and low-cost seismological stations (Raspberry Shake) have been already deployed in Beirut, most of them hosted by Lebanese citizens. These instrumental and open data access efforts were completed by participatory workshops with various stakeholders to improve the ergonomy of the web and application interfaces and to define roadmap for the implantation of future stations, consistently with most vulnerable populations identified by NGOs and the current knowledge on the air pollution and heat islands in Beirut
Physicochemical and Antibacterial Properties of Conventional and Two Premixed Root Canal Filling Materials in Primary Teeth
No full textInternational audienceIn this study, some physicochemical and antibacterial properties of three root canal filling materials for primary teeth, Calplus "CP" (Prevest DenPro, Lewes, DE, USA), Bio-C Pulpecto "Bio-CP" (Angelus, Basil, Londrina, Paraná, Brazil), and Zinc Oxide and Eugenol "ZOE" (Prevest DenPro, Lewes, DE, USA) were compared. For each material, the pH, solubility, contact angle, and crystalline microstructure under SEM were evaluated. Their antibacterial activity against Enterococcus faecalis was determined through direct tests. The Kruskal-Wallis test was used to analyze the results using a one-way analysis of variance on ranks. All the materials had an alkaline pH at 3, 24, and 72 h, with CalPlus having the highest (p < 0.05). Bio-CP was more soluble during the evaluation period (24 h) than ZOE and CalPlus (p < 0.05). Bio-CP and ZOE demonstrated the creation of crystallite structures on their surfaces after immersion in PBS at 37 • C, whereas CalPlus showed none. The lowest contact angle was observed for Bio-CP (53 ± 1.5 •); contact angles of (86 ± 4 •) and (96 ± 1 •), respectively, were observed after 10 s of the deposition of the water drop for CalPlus and ZOE. In conclusion, according to this study, there is still a need to develop new filling materials for primary teeth. ZOE, CalPlus and Bio-CP demonstrated different physicochemical and antibacterial properties, but none of the materials had optimal properties and could be considered the most suitable filling material for primary teeth pulpectomy. Bioceramics in their current state are not an alternative. The physicochemical and antibacterial properties still need improvement to fit the intricate anatomy of primary teeth
Electron tracks simulation in water: Performance comparison between GPU CPU and the EUMED grid installation
No full textInternational audiencePurposeWe explored different technologies to minimize simulation time of the Monte-Carlo method for trackgeneration following the Geant4-DNA processes for electrons in water.MethodsA GPU software tool is developed for electron track simulations. A similar CPU version is also developedusing the same collision models. CPU simulations were carried out on a single user desktop computer andon the computing grid France Grilles using 10 and 100 computing nodes. Computing time results for CPU,GPU, and grid simulations are compared with those using Geant4-DNA processes.ResultsThe CPU simulations better performs when the number of electrons is less than 104 with 100eV initialenergy, this number decreases as the energy increases. The GPU simulations gives better results whenthe number of electrons is more than 104 with initial energy of 100eV, this number decreases to 103 forelectrons with 10KeV and increases back with higher energy. The use of the grid introduces an additionalqueuing time which slows down the overall simulation performance. Thus, the Grid gives betterperformance when the number of electrons is over 105 with initial energy of 10KeV, and this numberdecreases as the energy increases.ConclusionsThe CPU is best suited for small numbers of primary incident electrons. The GPU is best suited when thenumber of primary incident particles occupies sufficient resources on GPU card in order to get animportant computing power. The grid is best suited for simulations with high number of primary incidentelectrons with high initial energy
Assessment of a novel deep learning-based marker-less motion capture system for gait study
No full textInternational audienceBackground. Marker-less systems based on digital video cameras and deep learning for gait analysis could have a deep impact in clinical routine. A recently developed system has shown promising results in terms of joint center position but has not been yet evaluated in terms of gait outcomes.Research question. How does this novel marker-less system compare to a marker-based reference system in terms of clinically relevant gait parameters?Methods. The deep learning method behind the developed marker-less system was trained on a dedicated dataset consisting of forty-one asymptomatic and pathological subjects each performing ten walking trials. The system could estimate the three-dimensional position of seventeen joint centers or keypoints (e.g., neck, shoulders, hip, knee, and ankles). We evaluated the marker-less system against a marker-based system in terms of differences in joint position (Euclidean distance), detection of gait events (e.g., heel strike and toe-off), spatiotemporal parameters (e.g., step length, time), kinematic parameters (e.g., hip and knee extension-flexion), and inter-trial reliability for kinematic parameters.Results. The marker-less system was able to estimate the three-dimensional position of joint centers with a mean difference of 13.1 mm (SD = 10.2 mm). 99% of the estimated gait events were estimated within 10 milliseconds of the corresponding reference values. Estimated spatiotemporal parameters showed zero bias. The mean and standard deviation of the differences of the estimated kinematic parameters varied by parameter (for example, the mean and standard deviation for knee extension flexion angle were -3.0° and 2.7°). Inter-trial reliability of the measured parameters was similar to that of the marker-based references.Significance. The developed marker-less system can measure the spatiotemporal parameters within the range of the minimum detectable changes obtained using the marker-based reference system. Moreover, except for hip extension flexion, the system showed promising results in terms of several kinematic parameters