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Search Results: 1 - 10 of 5113 matches for " Yves Didier Modtegue Bampel "
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Physicochemical and Thermal Characterization of Dura Palm Kernel Powder as a Load for Polymers: Case of Polyvinyl Chloride  [PDF]
Rolland Djomi, Lucien Jean Raymond Meva’a, Jean Nganhou, Gérard Mbobda, Abel Emmanuel Njom, Yves Didier Modtegue Bampel, Jean-Bosco Saha Tchinda
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.66001
Abstract: This work presents the physical and thermal characterization of the dura palm kernel powder of Cameroon for their use as fillers for polymers composites. The powders of palm kernel were obtained using a percussion grinder mill with an industrial microniser which allowed obtaining a powder less than 50 μm with an apparent density between 0,505 ≤ ρ ≤ 0,680 g/cm3 at 1.56 of relative humidity. The infrared of the powder of palm kernel shows the presence of phenols groups with a large band around 3341 cm-1, -C-H at 2917.02 cm-1 and -C-O at 1040 cm-1 as the main peaks. The polyvinyl chloride of infrared obtained shows the presence of -C-Cl, -CH2 and CH as the mains peaks. The infrared of 12.5% of palm kernel powder with polyvinyl chloride shows an increase of the CH2 and CH bonds and a decrease of the -OH bonds. Thermogravimetric analysis and differential scanning calorimetric analysis of powders, polyvinyl chloride and mixture showed that the mixing powders are intermediate between the polyvinyl chloride and palm kernel powder. The powder decreased the phase temperatures of the mixture from 98.58 to 95 for the glass transition temperature and from 515℃ to 459 for the crystallization temperature. The thermogravimetric curves of palm kernel powder and polyvinyl chloride have showed that these materials lose their different masses in three different phases, and the one of composite (mixture of polyvinyl chloride with 12.5% of palm kernel powder) in two different phases.
Approximate Compositional Values and Tissue Fatty Acid Profiles of Nile Tilapia (Oreochromis niloticus L.) Fed Azolla-Diets in Earthen Ponds  [PDF]
Youssouf Abou, Emile Didier Fiogbé, Yves Beckers, Jean-Claude Micha
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.29131
Abstract: The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P < 0.05). Dry matter and crude protein showed no significant differences (P > 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P < 0.05). Linolenic acid (LLA) decreased significantly when AM level in diets increased (P < 0.05). In contrast, arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) showed significantly higher values in fish fed high AM (P < 0.05). The n - 3/n - 6 ratio ranged from 0.35 to 0.49, with values being significantly higher in fish fed A20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.
Metabolic Properties of Fibers and Connective Tissue of Four Muscles from Bovine Carcasses  [PDF]
Marie-Pierre Ellies-Oury, Rollande Dumont, Didier Micol, Yves Durand, Brigitte Picard
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.616157
Abstract: Meat-grain-size (MGS) assessment is an empirical method for the early prediction of meat quality, a larger grain being synonymous with higher meat tenderness. The objective was to characterize 4 muscles (longissimus thoracis LT; rectus abdominis RA; longus colli LC; diaphragma D) of 5 coarse and 5 fine carcasses in terms of MGS in order to establish a link between muscular physicochemical properties and carcass MGS score. All comparisons were made of samples with similar fat content. The broiled sample hardness (shear force) was significantly higher for the coarse group than for the fine group (7.20 vs 5.89 kg; RA). Higher collagen content (27.94 vs 24.87 mg/g of dry matter in LT muscle; 15.86 vs 13.13 mg/g of dry matter in D muscle), higher oxidative metabolism (cytochrome-c oxidase; LT and D) but also higher glycolytic metabolism (lactate dehydrogenase; LT) were also observed in the coarse groups. Not all the muscles react in a similar way depending on the MGS group. Nevertheless, significant results are constant from one muscle to another, the RA being the only muscle for which the difference in hardness between the two groups is significant.
Spontaneous clustering in theoretical and some empirical stationary processes
Tomasz Downarowicz,Yves Lacroix,Didier Léandri
Mathematics , 2008,
Abstract: In a stationary ergodic process, clustering is defined as the tendency of events to appear in series of increased frequency separated by longer breaks. Such behavior, contradicting the theoretical "unbiased behavior" with exponential distribution of the gaps between appearances, is commonly observed in experimental processes and often difficult to explain. In the last section we relate one such empirical example of clustering, in the area of marine technology. In the theoretical part of the paper we prove, using ergodic theory and the notion of category, that clustering (even very strong) is in fact typical for "rare events" defined as long cylinder sets in processes generated by a finite partition of an arbitrary (infinite aperiodic) ergodic measure preserving transformation.
Impact of Capsular Switch on Invasive Pneumococcal Disease Incidence in a Vaccinated Population
Laura Temime, Pierre-Yves Boelle, Lulla Opatowski, Didier Guillemot
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003244
Abstract: Background Despite the dramatic decline in the incidence of invasive pneumococcal disease (IPD) observed since the introduction of conjugate vaccination, it is feared that several factors may undermine the future effectiveness of the vaccines. In particular, pathogenic pneumococci may switch their capsular types and evade vaccine-conferred immunity. Methodology/Principal Findings Here, we first review the literature and summarize the available epidemiological data on capsular switch for S. pneumoniae. We estimate the weekly probability that a persistently carried strain may switch its capsule from four studies, totalling 516 children and 6 years of follow-up, at 1.5×10?3/week [4.6×10?5–4.8×10?3/week]. There is not enough power to assess an increase in this frequency in vaccinated individuals. Then, we use a mathematical model of pneumococcal transmission to quantify the impact of capsular switch on the incidence of IPD in a vaccinated population. In this model, we investigate a wide range of values for the frequency of vaccine-selected capsular switch. Predictions show that, with vaccine-independent switching only, IPD incidence in children should be down by 48% 5 years after the introduction of the vaccine with high coverage. Introducing vaccine-selected capsular switch at a frequency up to 0.01/week shows little effect on this decrease; yearly, at most 3 excess cases of IPD per 106 children might occur due to switched pneumococcal strains. Conclusions Based on all available data and model predictions, the existence of capsular switch by itself should not impact significantly the efficacy of pneumococcal conjugate vaccination on IPD incidence. This optimistic result should be tempered by the fact that the selective pressure induced by the vaccine is currently increasing along with vaccine coverage worldwide; continued surveillance of pneumococcal populations remains of the utmost importance, in particular during clinical trials of the new conjugate vaccines.
The MIRELA framework: modeling and analyzing mixed reality applications using timed automata
Jean-Yves Didier,Bachir Djafri,Hanna Klaudel
Journal of Virtual Reality and Broadcasting , 2009,
Abstract: Mixed Reality (MR) aims to link virtual entities with the real world and has many applications such as military and medical ones. In many MR systems and more precisely in augmented scenes, one needs the application to render the virtual part accurately at the right time. To achieve this, such systems acquire data related to the real world from a set of sensors before rendering virtual entities. A suitable system architecture should minimize the delays to keep the overall system delay (also called end-to-end latency) within the requirements for real-time performance. In this context, we propose a compositional modeling framework for MR software architectures in order to specify, simulate and validate formally the time constraints of such systems. Our approach is first based on a functional decomposition of such systems into generic components. The obtained elements as well as their typical interactions give rise to generic representations in terms of timed automata. A whole system is then obtained as a composition of such defined components.To write specifications, a textual language named MIRELA (MIxed REality LAnguage) is proposed along with the corresponding compilation tools. The generated output contains timed automata in UPPAAL format for simulation and verification of time constraints. These automata may also be used to generate source code skeletons for an implementation on a MR platform.The approach is illustrated first on a small example. A realistic case study is also developed. It is modeled by several timed automata synchronizing through channels and including a large number of time constraints. Both systems have been simulated in UPPAAL and checked against the required behavioral properties.
Les Pseudoperisphinctinae (Ammonitina, Perisphinctidae) de l'horizon à Leckenbyi (Callovien supérieur, zone à Athleta) de Montreuil-Bellay (Maine-et-Loire, France) et description d'une nouvelle espèce, Choffatia isabellae [Pseudoperisphinctinae (Ammonitina, Perisphinctidae) from the Leckenbyi horizon (Upper Callovian, Athleta zone) of Montreuil-Bellay (Maine-et-Loire, France) and description of a new species, Choffatia isabellae]
Bonnot Alain,Boursicot Pierre-Yves,Ferchaud Patrice,Marchand Didier
Carnets de Géologie , 2008,
Abstract: Pseudoperisphinctinae (Ammonitina, Perisphinctidae) from the Leckenbyi horizon (Upper Callovian, Athleta zone) of Montreuil-Bellay (Maine-et-Loire, France) and description of a new species, Choffatia isabellae.- Many outcrops exposing the Mid-Callovian/Upper Callovian boundary have been found near Montreuil-Bellay (Maine-et-Loire). The lowermost bed of the Upper Callovian has been dated as the Leckenbyi horizon. It contains an abundant ammonite fauna (3125 specimens), in which Perisphinctidae make up just over half of the specimens. In company with reasonably well-known species such as Pseudopeltoceras leckenbyi (Bean), Orionoides pseudorion (Waagen), Subgrossouvria famulum (Bean) and S. crassa Gérard et Contaut, occurs a species, previously unknown, which is described in this article. Choffatia isabellae n. sp. differs markedly from contemporary Perisphinctidae, for it is distinguished by : 1) a long, smooth juvenile stage, 2) weakly developed ribbing, 3) the absence of parabolic ornamentation and 4) a high frequency of constrictions. As this species is unknown in the fauna of the uppermost Middle Callovian, along with many other species, including Peltoceras marysae Bonnot et alii, it must have colonised the northwestern part of the European platform via the southern margin of the Tethys during the transgressive interval which started at the beginning of the Late Callovian. This new species appears abruptly at the base of the Leckenbyi horizon, reaches its acme in the middle of the horizon, where it probably represents half of the Perisphinctidae, before becoming rare in the upper part of the horizon, then very rare in the Athleta horizon.
Analysis of some solutions to protect the western tombolo of Giens
Van Van Than,Yves Lacroix,Pierre Liardet,Didier Leandri
Physics , 2014,
Abstract: The tombolo of Giens is located in the town of Hyeeres (France). We recall the history of coastal erosion, and proeminent factors affecting the evolution of the western tombolo. We then discuss the possibility of stabilizing the western tombolo. Our argumentation relies on a coupled model integrating swells, currents, water levels and sediment transport. We present the conclusions of the simulations of various scenarios, including pre-existing propositions from coastal engineering offices. We conclude that beach replenishment seems to be necessary but not sufficient for the stabilization of the beach. Breakwaters reveal effective particularly in the most exposed northern area. Some solutions fulfill conditions so as to be elected as satisfactory. We give a comparative analysis of the efficiency of 14 alternatives for the protection of the tombolo.
Multi-Armed Bandits for Intelligent Tutoring Systems
Benjamin Clement,Didier Roy,Pierre-Yves Oudeyer,Manuel Lopes
Computer Science , 2013,
Abstract: We present an approach to Intelligent Tutoring Systems which adaptively personalizes sequences of learning activities to maximize skills acquired by students, taking into account the limited time and motivational resources. At a given point in time, the system proposes to the students the activity which makes them progress faster. We introduce two algorithms that rely on the empirical estimation of the learning progress, RiARiT that uses information about the difficulty of each exercise and ZPDES that uses much less knowledge about the problem. The system is based on the combination of three approaches. First, it leverages recent models of intrinsically motivated learning by transposing them to active teaching, relying on empirical estimation of learning progress provided by specific activities to particular students. Second, it uses state-of-the-art Multi-Arm Bandit (MAB) techniques to efficiently manage the exploration/exploitation challenge of this optimization process. Third, it leverages expert knowledge to constrain and bootstrap initial exploration of the MAB, while requiring only coarse guidance information of the expert and allowing the system to deal with didactic gaps in its knowledge. The system is evaluated in a scenario where 7-8 year old schoolchildren learn how to decompose numbers while manipulating money. Systematic experiments are presented with simulated students, followed by results of a user study across a population of 400 school children.
E-β-Ocimene, a Volatile Brood Pheromone Involved in Social Regulation in the Honey Bee Colony (Apis mellifera)
Alban Maisonnasse,Jean-Christophe Lenoir,Dominique Beslay,Didier Crauser,Yves Le Conte
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013531
Abstract: In honey bee colony, the brood is able to manipulate and chemically control the workers in order to sustain their own development. A brood ester pheromone produced primarily by old larvae (4 and 5 days old larvae) was first identified as acting as a contact pheromone with specific effects on nurses in the colony. More recently a new volatile brood pheromone has been identified: E-β-ocimene, which partially inhibits ovary development in workers.
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