Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 1 )

2018 ( 9 )

2017 ( 8 )

2016 ( 10 )

Custom range...

Search Results: 1 - 10 of 1626 matches for " Sylvain Niyonkuru "
All listed articles are free for downloading (OA Articles)
Page 1 /1626
Display every page Item
Colorectal Cancer: Epidemiological, Clinical and Histopathological Aspects in Burundi  [PDF]
Rénovat Ntagirabiri, Richard Karayuba, Gabriel Ndayisaba, Sylvain Niyonkuru, Moebeni Amani
Open Journal of Gastroenterology (OJGas) , 2016, DOI: 10.4236/ojgas.2016.63011
Abstract: Colorectal cancer is a major cause of morbidity and mortality throughout the world. There is no study about colorectal cancer in our country. The aim of the study was to assess epidemiological, clinical, therapeutic and histological aspects of colorectal cancer over a 10-year period (1999-2008) in Kamenge university hospital, Bujumbura, Burundi, by a descriptive retrospective study. A total of 37 cases of colorectal cancer, 22 males (59.5%) and 15 females (40.5%), mean age 50.8 years, were retrieved over the period of the study. The colorectal cancer was revealed by a rectal bleeding in 21 patients (56.8%) and an occlusive syndrome in 5 patients (13.5%). All patients underwent surgery. According to Dukes’ stages: 27% were A, 27% B, 19% C and 27% stage D. Histopathologically, 18 cases (46.7%) were differentiated adenocarcinoma, 14 cases (37.8%) undifferentiated adenocarcinoma, 2 cases of lymphoma and 2 cases of leiomyosarcoma. All patients underwent surgery. The hospitalization stay was a mean of 27 days. The prognosis was poor with a mortality rate of 13.5% in the hospital. In conclusion, colorectal cancer deserves awareness as a public health problem in our country.
Impact of acadja fisheries on fish assemblages in Lake Nokoué, Benin, West Africa Impact des pêcheries en acadjas sur les assemblages de poissons du Lac Nokoué au Bénin, Afrique de l’Ouest
Niyonkuru C.,Lalèyè P.A.
Knowledge and Management of Aquatic Ecosystems , 2010, DOI: 10.1051/kmae/2010033
Abstract: Acadjas are artificial systems aimed at enhancing fish production by providing additional substrata for development of plants and animals upon which the fish will feed. This study aims to evaluate the impact of acadjas on fish assemblages and on conservation of the fish fauna diversity in Lake Nokoué in Benin. Between June 2003 and September 2004, experimental acadjas were installed and monitored. Fish samples were obtained from two areas of Lake Nokoué (Ganvié and Zogbo stations) within and without acadjas with the assistance of artisanal fishermen. Physico-chemical parameters were also measured inside and outside of the experimental acadjas in the same two stations. Twenty-five fish species belonging to 17 families were identified in acadjas out of a total of 51 species belonging to 34 families inventoried in 2001 at Lake Nokoué (i.e. 49% of the specific richness of the ichthyofauna). Fifty-six percent of fish fauna caught in acadjas are estuarine forms and represent 78% of all estuarine forms of Lake Nokoué in 2001. The analysis of variance showed that the specific richness of the acadjas varied significantly according to the station (p < 0.05), with a high specific richness in Zogbo station where acadjas are less abundant. Acadjas are selective for some fish species such as cichlids which represent 95% of the total numeric abundance and contribute about 90% of the total fish biomass. The high densities of acadjas could contribute to the reduction of the richness of fish fauna. Rational management could consist of reorganizing the surface areas of Lake Nokoué by preserving areas for other fish species that do not colonize acadjas. Les acadjas, ou parcs à poissons, sont des systèmes artificiels visant l’augmentation de la production de poisson en fournissant du substrat complémentaire pour le développement des plantes et animaux devant servir de nourriture aux poissons. Cette étude a pour objectif d’évaluer l’impact des acadjas sur les assemblages des poissons et la conservation de la diversité ichtyologique du lac Nokoué au Bénin. Ainsi, entre juin 2003 et septembre 2004, les acadjas expérimentaux ont été installés et suivis. Les échantillons de poissons ont été obtenus dans les deux stations (Ganvié et Zogbo) du lac Nokoué à l’intérieur et à l’extérieur des acadjas à l’aide des pêcheurs artisanaux. Les paramètres physico-chimiques ont été également mesurés à l’intérieur et à l’extérieur des acadjas expérimentaux des mêmes stations. Au total, 25 espèces de poissons appartenant à 17 familles ont été identifiées à l’intérieur des acadjas sur un total de
Impact of acadja fisheries on the population dynamics of Sarotherodon melanotheron and Hemichromis fasciatus in a Lake Nokoué (Benin, West Africa) Impact des pêcheries en acadjas sur la dynamique des populations de Sarotherodon melanotheron et Hemichromis fasciatus du lac Nokoué au Bénin (Afrique de l’Ouest)
Niyonkuru C.,Lalèyè P.A.,Moreau J.
Knowledge and Management of Aquatic Ecosystems , 2010, DOI: 10.1051/kmae/2010019
Abstract: In Lake Nokoué fishermen have developed the acadjas system which operates as an extensive aquaculture practice. Little is known about the population dynamics of fish fauna which colonizes those acadjas. Therefore, population parameters of two cichlids of Lake Nokoué, Sarotherodon melanotheron and Hemichromis fasciatus, sampled in areas within and without acadjas were investigated using length-frequency data collected between June 2003 and December 2004. For the two species, asymptotic length, L∞ was higher within than without acadjas (26.8 cm and 24.1 cm respectively for S. melanotheron; 18.5 cm and 16.5 cm respectively for H. faciatus). K and Φ′ values recorded outside acadjas were higher than inside acadjas for H. fasciatus whereas the same values were very slightly different without and within acadjas for S. melanotheron. H. fasciatus is a fish predator and branches or woody debris of acadjas are not favourable for its hunting activities.The total and natural mortality rates for the two species were higher outside than inside acadjas showing so the role of protection insured by acadjas systems. Acadjas have more impact on H. fasciatus than on S. melanotheron. A possibility of management is to reorganize the distribution of acadjas over Lake Nokoué in order to keep some areas in which no acadjas would be allowed for fish species that growth is better without acadjas. Au lac Nokoué, les pêcheurs ont développé des systèmes d’acadjas qui fonctionnent comme une sorte d’aquaculture extensive. Peu est connu sur la dynamique des populations des espèces de poissons qui colonisent ces acadjas. C’est ainsi que des investigations ont été menées sur les paramètres de population de deux espèces de poissons-cichlidés du lac Nokoué, Sarotherodon melanotheron et Hemichromis fasciatus. Les échantillons ont été collectés à l’intérieur et à l’extérieur des acadjas entre juin 2003 et décembre 2004, puis analysés en utilisant les distributions des fréquences des tailles à l’aide du logiciel FiSAT. Pour les deux espèces de poissons, la taille asymptotique L∞ était plus élevée à l’intérieur qu’à l’extérieur des acadjas (respectivement 26,8 cm et 24,1 cm pour S. melanotheron; puis respectivement 18,5 cm et 16,5 cm pour H. faciatus). Les valeurs de K et Φ′ enregistrées à l’extérieur des acadjas étaient plus élevées que celles enregistrées à l’intérieur des acadjas pour H. fasciatus, alors que les mêmes valeurs étaient légèrement différentes à l’extérieur et à l’intérieur des acadjas pour S. melanotheron. H. fasciatus est un poisson prédateur et les branches et les morceaux de
Left Eigenvector of a Stochastic Matrix  [PDF]
Sylvain Lavalle′e
Advances in Pure Mathematics (APM) , 2011, DOI: 10.4236/apm.2011.14023
Abstract: We determine the left eigenvector of a stochastic matrix M associated to the eigenvalue 1 in the commutative and the noncommutative cases. In the commutative case, we see that the eigenvector associated to the eigenvalue 0 is (N1,Nn) , where Ni is the ith iprincipal minor of N=MIn , where In is the identity matrix of dimension n. In the noncommutative case, this eigenvector is (P1-1,Pn-1) , where Pi is the sum in Q《αij》 of the corresponding labels of nonempty paths starting from i and not passing through i in the complete directed graph associated to M .
Encoding of local and global cues in domestic dogs’ spatial working memory  [PDF]
Sylvain Fiset, Nathalie Malenfant
Open Journal of Animal Sciences (OJAS) , 2013, DOI: 10.4236/ojas.2013.33A001
Abstract: The current study investigated whether domestic dogs encode local and/or global cues in spatial working memory. Seven dogs were trained to use a source of allocentric information (local and/or global cues) to locate an attractive object they saw move and disappear behind one of the three opaque boxes arrayed in front of them. To do so, after the disappearance of the target object and out of the dogs’ knowledge, all sources of allocentric information were simultaneously shifted to a new spatial position and the dogs were forced to follow a U-shaped pathway leading to the hiding box. Out of the seven dogs that were trained in the detour problem, only three dogs learned to use the cues that were moved from trial to trial. On tests, local (boxes and experimenter) and/or global cues (walls of the room) were systematically and drastically shifted to a new position in the testing chamber. Although they easily succeeded the control trials, the three dogs failed to use a specific source of allocentric information when local and global cues were put in conflict. In discussion, we explore several hypotheses to explain why dogs have difficulties to use allocentric cues to locate a hidden object in a detour problem and why they do not differentiate the local and global cues in this particular experimental setting.
Main Features of a Complete Ultrasonic Measurement Model: Formal Aspects of Modeling of Both Transducers Radiation and Ultrasonic Flaws Responses  [PDF]
Michel Darmon, Sylvain Chatillon
Open Journal of Acoustics (OJA) , 2013, DOI: 10.4236/oja.2013.33A008

This paper aims at describing the theoretical fundamentals of a reciprocity-based ultrasonic measurement model. This complete inspection simulation can be decomposed in two modeling steps, one dedicated to transducer radiation and one to flaw scattering and echo synthesis. The physical meaning of the input/output signals used in these two modeling tools is defined and the theoretical principles of both field calculation and echo computation models are then detailed. The influence on the modeling results of some changes in the simulated configuration (as the incident angle) or some input signal parameters (like the frequency) are studied: it is thus theoretically established that the simulated results can be compared between each other in terms of amplitude for numerous applications when changing some inspection parameters in the simulation but that a calibration for echo calculation is generally required.

Application of the Frobenius Method to the Schrodinger Equation for a Spherically Symmetric Hyperbolic Potential  [PDF]
Hippolyte Nyengeri, Rénovat Nizigiyima, Eugène Ndenzako, Félix Bigirimana, Dieudonné Niyonkuru, Audace Girukwishaka
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104950
In this paper, an efficient technique for computing the bound state energies and wave functions of the Schrodinger Equation (SE) associated with a new class of spherically symmetric hyperbolic potentials is developed. This technique is based on a recent approximation scheme for the orbital centrifugal term and on the use of the Frobenius method (FM). The bound state eigenvalues are given as zeros of calculable functions. The corresponding eigenfunctions can be obtained by substituting the calculated energies into the recurrence relations for the expanding coefficients of the Frobenius series representing the solution. The excellent performance of this technique is illustrated through numerical results for some special cases like Poschl-Teller potential (PTP), Manning-Rosen potential (MRP) and Poschl-Teller polynomial potential (PTPP), with an application to the Gaussian potential well (GPW). Comparison with other methods is presented. Our results agree noticeably with the previously reported ones.
Invariants and Other Structural Properties of Biochemical Models as a Constraint Satisfaction Problem
Sylvain Soliman
Algorithms for Molecular Biology , 2012, DOI: 10.1186/1748-7188-7-15
Abstract: In our case, this analysis brings both qualitative and quantitative information on the models, in the form of conservation laws, consistency checking, etc. thanks to finite domain constraint programming. It is noticeable that some of the most recent optimizations of standard invariant computation techniques in Petri nets correspond to well-known techniques in constraint solving, like symmetry-breaking. Moreover, we show that the simple and natural encoding proposed is not only efficient but also flexible enough to encompass sub/sur-invariants, siphons/traps, etc., i.e., other Petri net structural properties that lead to supplementary insight on the dynamics of the biochemical system under study.A simple implementation based on GNU-Prolog's finite domain solver, and including symmetry detection and breaking, was incorporated into the BIOCHAM modelling environment and in the independent tool Nicotine. Some illustrative examples and benchmarks are provided.Reaction models like those of reactome.org, KEGG pathway database [1] or biomodels.net represent a growing part of Systems Biology especially for metabolic or signalling pathways, cell-cycle and more generally post-genomic regulation systems. They build on established standards like BioPAX or SBML [2] to facilitate the exchange and comparison of models and benefit from a large number of available tools, especially ODE integration based simulators.The use of Petri nets to represent those models, taking into account the difference between compounds and reactions in the graph, and make available various kinds of analyses is quite old [3], however it remains somehow focused towards mostly qualitative and structural properties. Some have been used for module decomposition, like (I/O) T-invariants [4,5], related to dynamical notions of elementary flux modes [6]. However, there is, to our knowledge, very little use of P-invariant computation, which provides both qualitative information about some notion of module related to
Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities
Sylvain Deville
Materials , 2010, DOI: 10.3390/ma3031913
Abstract: The freeze-casting of porous materials has received a great deal of attention during the past few years. This simple process, where a material suspension is simply frozen and then sublimated, provides materials with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. This review focuses on the recent results on the process and the derived porous structures with regards to the biomaterials applications. Of particular interest is the architecture of the materials and the versatility of the process, which can be readily controlled and applied to biomaterials applications. A careful control of the starting formulation and processing conditions is required to control the integrity of the structure and resulting properties. Further in vitro and in vivo investigations are required to validate the potential of this new class of porous materials.
Contemporaneo e política
Lazarus, Sylvain;
Educa??o & Realidade , 2012, DOI: 10.1590/S2175-62362012000200004
Abstract: the article deals with the crisis of politics and of the contemporary as a result of a name capture from the state field. regarding politics, all the attempts since 1968 of reconstituting it away from the state, from the point of view of people and the interior of situations, are now over. there is also a reflection about the separate nature of the state and about the thinking of people and the forms of subjectivity. therefore, this text aims at evaluating the rupture of thinking using the thesis that the contemporary nature of the state as a separate state is incompatible with the thinking of people guided to the possible. the article searches, at the end, questions the anthropological discipline and what it can enunciate about the contemporary today.
Page 1 /1626
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.