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Search Results: 1 - 10 of 223613 matches for " Rénovat Nizigiyima "
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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.
The Explicit Fatunla’s Method for First-Order Stiff Systems of Scalar Ordinary Differential Equations: Application to Robertson Problem  [PDF]
Hippolyte Nyengeri, Eugène Ndenzako, Rénovat Nizigiyimana
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105291
Ordinary differential equations (ODEs) are among the most important mathe-matical tools used in producing models in the physical sciences, biosciences, chemical sciences, engineering and many more fields. This has motivated re-searchers to provide efficient numerical methods for solving such equations. Most of these types of differential models are stiff, and suitable numerical methods have to be used to simulate the solutions. This paper starts with a sur-vey on the basic properties of stiff differential equations. Thereafter, we present the explicit one-step algorithm proposed by Fatunla to solve stiff systems of first-order scalar ODEs. As an illustrative example, we consider the Robertson problem (RP) which is known to be stiff. The results obtained with the explicit Fatunla method (EFM) are compared with those computed by the solver RADAU which is based on implicit Runge-Kutta methods. Our results are in good agreement with the latter ones.
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.
Esophageal Cancer: Epidemiological, Clinical and Histopathological Aspects over a 24-Years Period at Kamenge University Hospital, Bujumbura, Burundi  [PDF]
Rénovat Ntagirabiri, Richard Karayuba, Gabriel Ndayisaba, Aline Nduwimana, Jean Claude Niyondiko
Open Journal of Gastroenterology (OJGas) , 2016, DOI: 10.4236/ojgas.2016.64014
Abstract: Aim: There were no data about esophageal cancer in Burundi. The aim of the study was to highlight the epidemiological, clinical and histopathological aspects of the esophageal cancer. Method: A retrospective study over a 24-years period (from January 1988 to December 2011) was carried out at Kamenge university hospital, including patients with esophageal cancer. The cases were selected on basis of the histological evidence of the cancer. Results: A total of 34 cases were retrieved and included for analysis. Among them, 24 patients (70.5%) were males. The esophageal cancer constituted 8.6% of digestive cancers over the period of the study. The average age was 50.9 years. It was revealed by dysphagia in 32 patients (94.1%) and was concomitantly metastatic in 12 patients. The squamous cell carcinoma was 30 cases (88.2%). 27 patients underwent a curative resection, but the outcome and prognosis were poor. In-hospital mortality and morbidity rates were respectively 8.8% and 17.7%. Conclusion: The present study showed evidence that the esophageal cancer in our country had the same characteristics and distribution as well as in developing countries. It had a poor prognosis and efforts had to be done in the early cancer detection.
Frobenius Series Solutions of the Schrodinger Equation with Various Types of Symmetric Hyperbolic Potentials in One Dimension  [PDF]
Hippolyte Nyengeri, René Simbizi, Audace Girukwishaka, Rénovat Nizigiyimana, Eugène Ndenzako
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104728
The Schrodinger equation (SE) for a certain class of symmetric hyperbolic potentials is solved with the aid of the Frobenius method (FM). The bound state energies are given as zeros of a calculable function. The calculated bound state energies are successively substituted into the recurrence relations for the expanding coefficients of the Frobenius series representing even and odd solutions in order to obtain wave functions associated with even and odd bound states. As illustrative examples, we consider the hyperbolic Poschl-Teller potential (HPTP) which is an exactly solvable potential, the Manning potential (MP) and a model of the Gaussian potential well (GPW). In each example, the bound state energies obtained by means of the FM are presented and compared with the exact results or the literature ones. In the case of the HPTP, we also make a comparison between exact bound state wave functions and the eigenfunctions obtained by means of the present approach. We find that our results are in good agreement with those given by other methods considered in this work, and that our class of potentials can be a perfect candidate to model the GPW.
Power Aware Routing Protocol (PARP) for Wireless Sensor Networks  [PDF]
R. Prema, R. Rangarajan
Wireless Sensor Network (WSN) , 2012, DOI: 10.4236/wsn.2012.45019
Abstract: Several wireless sensor network applications ought to decide the intrinsic variance between energy efficient communication and the requirement to attain preferred quality of service (QoS) such as packet delivery ratio, delay and to reduce the power consumption of wireless sensor nodes. In order to address this challenge, we propose the Power Aware Routing Protocol (PARP), which attains application-specified communication delays at low energy cost by dynamically adapting transmission power and routing decisions. Extensive simulation results prove that the proposed PARP attains better QoS and reduced power consumption.
Studies on Dissolution Behaviour of Nanoparticulate Curcumin Formulation  [PDF]
R. Ravichandran
Advances in Nanoparticles (ANP) , 2013, DOI: 10.4236/anp.2013.21010

Curcumin is the main biologically active phytochemical compound of turmeric that has been widely used by ancient cultures throughout Asia. However the dissolution rate limited absorption and pre-absorption degradation limits its use as a potential therapeutic. In this study an attempt has been made to overcome the above limitations by curcumin delivery through nanotechnology. Nanocurcumin solid dosage formulations were prepared and studied for its dissolution behaviour. Considerable improvement in the dissolution behavior was observed in the drug nanocrystal-loaded solid dosage forms. This is expected to enhance the bioavailability of poorly soluble medicinal herbs such as turmeric in the body.

Pharmacokinetic Study of Nanoparticulate Curcumin: Oral Formulation for Enhanced Bioavailability  [PDF]
R. Ravichandran
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.43037

Curcumin, a bioactive component of turmeric, which is a commonly used spice and nutritional supplement, is isolated from the rhizomes of Curcuma longa Linn. (Zingiberaceae). In recent years, the potential pharmacological actions of Curcumin in inflammatory disorders, cardiovascular disease, cancer, Alzheimer’s disease and neurological disorders have been shown. However, the clinical application of Curcumin is severely limited by its main drawbacks such as instability, low solubility, poor bioavailability and rapid metabolism. Multifarious nanotechnology-based drug delivery systems for Curcumin including liposomes, polymeric nanoparticles, solid lipid nanoparticles, micelles, nanogels, nanoemulsions, complexes and dendrimer/dimer, have been attempted to enhance the oral bioavailability, biological activity or tissue-targeting ability of Curcumin. We attempted the nanosuspensions based delivery of curcumin. Nanonisation renders curcumin completely dispersible in aqueous media. To enhance the curcumin absorption by oral administration, nanoparticulate solid oral formulation of curcumin was prepared by us and the resulting capsule was then examined for its efficiency on bioavailability in Male Wistar rats at a dose of 100 mg curcumin/kg body weight and the pharmacokinetic parameters were compared to those of normal curcumin powder and a commercial curcumin capsule CUR-500. The bio-distribution of curcumin in organs of rat was also studied. Nanoparticulation significantly raised the curcumin concentration in selective organs in the body. The results obtained provide promising results for nanoparticulate Curcumin to improve its biological activities. Enhanced bioavailability of curcumin in the form of nanoparticle is likely to bring this promising natural product to the forefront of therapeutic agents for treatment of human disease. The available information also strongly suggests that nano-formulation of ingredients such as curcumin may be used as a novel nutrient delivery system too.

The Arithmetic Mean Standard Deviation Distribution: A Geometrical Framework  [PDF]
R. Caimmi
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411A4001

The current attempt is aimed to outline the geometrical framework of a well known statistical problem, concerning the explicit expression of the arithmetic mean standard deviation distribution. To this respect, after a short exposition, three steps are performed as 1) formulation of the arithmetic mean standard deviation, \"\", as a function of the errors, \"\", which, by themselves, are statistically independent; 2) formulation of the arithmetic mean standard deviation distribution, \"\", as a function of the errors, \"\"; 3) formulation of the arithmetic mean standard deviation distribution, \"\", as a function of the arithmetic mean standard deviation, \"\", and the arithmetic mean rms error, \"\". The integration domain can be expressed in canonical form after a change of reference frame in the n-space, which is recognized as an infinitely thin n-cylindrical corona where the symmetry axis coincides with a coordinate axis. Finally, the solution is presented and a number of (well known) related parameters are inferred for sake of completeness.

Optimized Parameter Combinations of Hydraulic Damper Modules  [PDF]
R. Sonnenburg
Journal of Transportation Technologies (JTTs) , 2014, DOI: 10.4236/jtts.2014.43025

This paper is devoted to the problem of finding optimized parameter combinations of automotive damper modules. Different cost functions using the amplitude spectrum of the excitation and the frequency response function of the car model will be investigated and it is shown that for three different arbitrary road excitations there exists a parameter combination of top mount stiffness, piston rod mass and damping constant that provides an optimum for the dynamic wheel load fluctuation. The achieved advantage of the optimized damper module regarding the dynamic wheel load fluctuation compared to a simple damper in a two mass vibration system can reach up to 20 percent.

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