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Search Results: 1 - 10 of 8192 matches for " Michel Mbina "
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New Computerized Method for the Geochemical Classification of Precambrian Carbonate Rocks: Case of a Set of African Cap Carbonates  [PDF]
Hélène Miche, Roland Simler, Pascal Affaton, Olivia Mickala, Florent Boudzoumou, Michel Mbina
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.410A005

Post-sedimentary transformations have masked or completely obliterated the structures and textures of Precambrian carbonate rocks. Therefore, methods of classification of the carbonate rocks founded on the observation of primary structures or textural characteristics are ill-adapted. Consequently, only certain geochemical classification methods allow us to distinguish the various rock-types in the case of Neoproterozoic carbonates. After presenting the most suitable geochemical classifications, we propose a new classification into 14 groups based on a regular ternary diagram with computerized data input. For each sample of carbonate rock, analysis of calcium and magnesium contents allows us to calculate the input data for our diagram i.e. the percentages of Calcite, Dolomite and Insoluble Residue. To automate the application of this diagram, input parameters are created in a descriptive file “Roches.ternaires.txt” using an option called “Ternaires” in the “Diagrammes” software developed by Roland Simler. Thirty cap carbonates of Africa are used to validate this new method.

Growth, Duplication and Lateral Mutual Compressive Deformation of Akouemma hemisphaeria on the Seafloor of Okondja Basin at 2.2 Ga (Gabon)  [PDF]
Ambroise Edou-Minko, Mathieu Moussavou, Tomohiko Sato, Yusuke Sawaki, Simplice Ndong Ondo, Richard Maire, Guillaume Fleury, Michel Mbina Mounguengui, Anders Kaestner, Richard Ortega, Stéphane Roudeau, Asuncion Carmona, Makaya Mvoubou, Benjamin Musavu Moussavou, Osamu Sasaki, Shigenori Maruyama
International Journal of Geosciences (IJG) , 2017, DOI: 10.4236/ijg.2017.89067
A colony of macro-fossils Akouemma hemisphaeria has been described in the Paleoproterozoic sedimentary basin of Okondja, Gabon. These fossils are classified into two groups according to their spheroidal or elongated forms. The spheroidal shapes are similar, have a tripartite structure with two hemispheres and a median disc and gradually pass to the elongated forms. These elongated forms have a pronounced bipartite tendency to two “hemispheres” separated by a median surface, and often have several ovoid “pieces” attached. The elongated specimens show both lateral growth marks and signs of fission. Growth marks are characterized by unidirectional homogeneous side elongations and lateral bud-like protuberances. The signs of fission are marked by circular furrows perpendicular to the direction of elongation, called “constriction furrows” with varying depths depending on the degree of fission of the specimen and internal vertical “division planes”. All of these ovoid and elongated specimens have undergone significant initial deformations due mainly to mutual lateral compressions in tabular beds. The Akouemma hemisphaeria macro-organisms, which were primitive probably sessile organisms, lived on the seafloor. They provide the oldest known record of macro-organisms on Earth having vegetative growth and asexual reproduction by budding, lateral elongation and fission. Their mutual lateral deformations would result from their growth.
Variable selection in multiple regression with random design
Alban Mbina Mbina,Guy Martial Nkiet,Assi Nguessan
Statistics , 2015,
Abstract: We propose a method for variable selection in multiple regression with random predictors. This method is based on a criterion that permits to reduce the variable selection problem to a problem of estimating suitable permutation and dimensionality. Then, estimators for these parameters are proposed and the resulting method for selecting variables is shown to be consistent. A simulation study that permits to gain understanding of the performances of the proposed approach and to compare it with an existing method is given.
Antidiabetic Prescriptions at the University Hospital Center of Libreville (Gabon) Facing the Concept of Therapeutic Inertia: An Andragogical Perspective  [PDF]
Marie-Pierrette Ntyonga-Pono, Marie Félix Gorra, Emeline Mbina-Guidat, Natacha Bililhi-Boubeya, Peggy Bilogue, Ludvine Bifoume-Ndong, Eric Augustin Baye
Journal of Diabetes Mellitus (JDM) , 2018, DOI: 10.4236/jdm.2018.84014
Abstract: Context: Diabetes mellitus is experiencing an alarming progression throughout the world, but more and more drugs are available with the use not always adapted. The aim of this work is to analyze the anti-diabetic prescriptions at the university hospital center of Libreville (Gabon) and confront them with the concept of therapeutic inertia. Patients and Methods: In diabetics coming for their periodic control, we transcripted for 2 months, beyond their characteristics, their glycated hemoglobin rate and the treatment followed. Results: 200 patients have consulted and among them, 160 (80%) had done their A1c analysis. 46% had an A1c ≤ 7% and 54% above with sometimes an unsuitable treatment evoking therapeutic inertia, the factors of which we discuss. Conclusion: Therapeutic inertia is a multifactorial problem, one of the components of which may be the resistance to change of the adult learners who are the practitioners.
The fitness of African malaria vectors in the presence and limitation of host behaviour
Lyimo Issa N,Haydon Daniel T,Mbina Kasian F,Daraja Ally A
Malaria Journal , 2012, DOI: 10.1186/1475-2875-11-425
Abstract: Background Host responses are important sources of selection upon the host species range of ectoparasites and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors, and assess its ability to predict their known host species preferences in nature. Methods Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis and Anopheles gambiae sensu stricto in the presence and limitation of host behaviour were conducted in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials, mosquitoes were released within the SFS and allowed to forage overnight on a host that was free to exhibit a natural behaviour in response to insect biting. In the other, mosquitoes were allowed to feed directly on from the skin surface of immobile hosts. The feeding success and subsequent fitness of vectors under these conditions were investigated on six host types (humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less effective at preventing mosquito bites than those of common alternatives. Results Anopheles arabiensis generally had greater feeding success when applied directly to host skin than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae s.s. obtained blood meals from free and restrained hosts with similar success from most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free to exhibit behaviour, than those who were immobilized during feeding trials. Conclusions Allowing hosts to move freely during exposure to mosquitoes was associated with moderate reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of mosquitoes that were able to feed upon them. This suggests that physical defensive behaviours exhibited by common host species including humans do not impose substantial fitness costs on African malaria vectors.
City Development, Natural Resources and Human Impact: The Case of Medellin, Colombia  [PDF]
Michel Hermelin
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.48058

Medellin is a 3.5 M inhabitant city located in an Andean valley in northwestern Colombia. Its initial prosperity was due to agriculture and cattle-raising carried out in the valley itself and sold to the surrounding gold mining fields. The investment of these monies in coffee plantations and industry boosted the city development, accelerated urban growth, and since the middle of twentieth century, relegated food production to surrounding regions, which are also responsible for almost the totality of natural resource supply: water, electricity, food, building and industrial raw materials. Among the problems which will have to be solved in order to reach a sustainable development are relocation of population living in areas exposed to natural risks, improvement of road communications with surrounding regions and of internal public transportation and pollution control.

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.

DarcyTools: A Computer Code for Hydrogeological Analysis of Nuclear Waste Repositories in Fractured Rock  [PDF]
Urban Svensson, Michel Ferry
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.26044

A computer code for simulation of groundwater flow and transport is described. Both porous and fractured media are handled by the code. The main intended application is the analysis of a deep repository for nuclear waste and for this reason flow and transport in a sparsely fractured rock is in focus. The mathematical and numerical models are described in some detail. In short, one may say that the code is based on the traditional conservation and state laws, but also embodies a number of submodels (subgrid processes, permafrost, etc). An unstructured Cartesian grid and a finite volume approach are the key elements in the discretization of the basic equations. A multigrid solver is part of the code as well as a parallelization option based on the SPMD (Single-Program Multiple-Data) method. The main application areas are summarized and an application to a deep repository is discussed in some more detail.

Urban Trends and Economic Development in China: Geography Matters!  [PDF]
Michel Dimou, Alexandra Schaffar
Current Urban Studies (CUS) , 2014, DOI: 10.4236/cus.2014.23016
Abstract: The aim of this paper is to document the role of spatial effects in the relationship between urban trends and economic development in China, between 1984 and 2004. During this period the Chi-nese urban system experienced dramatic changes, with significant rural-urban, intra-provincial and interprovincial migration, mainly after the 1993 reforms that eased the former Hukou rule and abolished the prevailing cross-region labor mobility restrictions. This study draws upon recent econometrical tools based on spatial panel data models, developed in order to deliver evidence for a linear relationship between urbanization rates and GDP per capita and an inverted-U relationship between urban primacy and GDP per capita in the Chinese provinces.
Mec1-Dependent Phosphorylation of the Scc3 Subunit of Cohesin during Mitosis in Budding Yeast  [PDF]
Nathalie Grandin, Michel Charbonneau
Advances in Bioscience and Biotechnology (ABB) , 2015, DOI: 10.4236/abb.2015.63015
Abstract: Cohesin is an evolutionary conserved complex that controls chromosome segregation during mitosis. Here we show that, in response to DNA damage, Saccharomyces cerevisiae Scc3, one of the major regulatory subunits of the Smc1-Smc3-Scc1 cohesin ring, is phosphorylated on S/T-Q residues. This event depended on the Mec1 checkpoint kinase as well as on cell cycle arrest triggered by the DNA damage checkpoint network. This phosphorylation event also took place during mitosis of an unperturbed cell cycle. The present finding that S. cerevisiae Scc3 is phosphorylated during mitosis represents a potentially important new regulatory step in cohesin’s mitotic functions.
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