检索结果-南通市图书馆

Quasi-Normal Modes of Gravitational Perturbation around a Reissner-Nordstroem Black Hole Surrounded by Quintessence

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2009年第10期26卷 228-231页

作者： mahamat saleh Bouetou Bouetou Thomas Timoleon Crepin Kofane Department of Physics Faculty of Science University of Yaounde I PO Box 812 Cameroon Ecole Nationale Supérieure Polytechnique University of Yaounde I PO Box 8390 Cameroon The Abdus Salam International Centre for Theoretical Physics PO Box 586 Strada Costiera Ⅱ-34014 Trieste Italy

We investigate quasi-normal （QN） modes of gravitational perturbation around a Reissner-Nordstroem black hole surrounded by quintessence. The third-order Wentzel-Kramers-Brillouin approximation is used to evaluate QN frequencies. The behavior of the gravitational perturbation is plotted for some frequencies. Due to the presence of quintessence, QN modes of the Reissner-Nordstroem black hole damp at a slower rate.

关键词： No English Keyword

Quasi-Local Energy Distribution and Thermodynamics of Reissner-Nordstrom Black Hole Surrounded by Quintessence

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2011年第2期55卷 291-295页

作者： mahamat saleh Bouetou Bouetou Thomas Timoleon Crepin Kofane Department of Physics Faculty of Science University of Yaounde Dpartment of Physics Higher Teacher's Training College University of Maroua Ecole Nationale Superieure Polytechnique University of Yaounde

We investigate quasi-local energy distribution and thermodynamics of the Reissner-Nordstr6m black hole space-time surrounded by quintessence. We use the quasi-local energy distribution from Einstein energy-momentum complex. We plot the variation of the energies, temperature and heat capacity with the state parameter related to the quintessence ωq. We show that due to the presence of quintessence, the total energy of the outer region as well as the temperature and heat capacity decreases with the increase of the density of quintessence, while the total energy of the black hole region increases.

关键词： quasi-local energy distribution thermodynamics Reissner-NordstrSm black hole quintessence

Hawking radiation from a five-dimensional Lovelock black hole

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2015年第5期10卷 109-113页

作者： mahamat saleh Bouetou Bouetou Thomas Timoleon Crepin Kofane Department of Physics Faculty of Science University of YaoundeI P.O. Box 812 Yaounde Cameroon Department of Physics Higher Teachers' Training College University of Maroua P.O. Box 55 Maroua Cameroon National Advanced School of Engineering University of Yaounde I P.O. Box 8390 Yaounde Cameroon The Max Planck Institute for the Physics of Complex Systems Nothnitzer Strasse 38 01187 Dresden Germany

We investigate Hawking radiation from a five-dimensional Lovelock black hole using the Hamilton- Jacobi method. The behavior of the rate of radiation is plotted for various values of tile ultraviolet correction parameter and the cosmological constant. The results show that, owing to the ultraviolet correction and the presence of dark energy represented by the cosmological constant, the black hole radiates at a slower rate in comparison to the case without ultraviolet correction or cosmological constant. Moreover, the presence of the cosmological constant makes the effect of the ultraviolet correction on the black hole radiation negligible.

关键词： Hawking radiation Lovelock black hole Hamilton-Jacobi method

Thermomechanical Characterization of Three Soils of Abeche in Chad

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Open Journal of Civil Engineering 2024年第3期14卷 348-362页

作者： mahamat saleh Abdel-Khadir Abdallah Dadi mahamat Abderahman Adoum Oumar Mahamoud Youssouf Khayal Salif Gaye Energy and Materials Research Laboratory (LREM-INSTA) National Higher Institute of Science and Technology of Abch Abch Chad Faculty of Physics University of NDjamena NDjamena Chad Laboratory of Energy Electricity and Economic Materials (LM3E) Iba Der Thiam University of This This Senegal

The study carried out concerns the valorization of agricultural waste for the development of biosourced materials that can be used as insulation in homes. This article is devoted to the influence of gum arabic on the mechanical and thermal properties of clay soils in the town of Abéché. The mechanical tests were carried out using the CBR press equipped with two devices (bending device and compression device). Thermal property such as thermal conductivity was determined by the hot wire method and thermal resistance was derived by calculation. Thus, the tests were carried out on test pieces made from a mixture of clay and gum arabic in solution. The experimental program includes seven formulations (0%, 2%, 4%, 6%, 8%, 10% and 12%). The results obtained showed that the best flexural and compressive strengths are obtained by using gum arabic with a rate of 8% and a maximum stress of 4.3 MPa. In addition, the thermal results also showed that the thermal conductivity decreases when the percentage of gum arabic increases, which makes it possible to increase the thermal resistance, thus confirming the capacity of gum arabic to provide thermal insulation.

关键词： Soils Mechanical Characterization Thermal Characterization Thermal Conductivity Thermal Resistance

Perturbation-Iteration Method for Solving Mathematical Model of Glucose and Insulin in Diabetic Human during Physical Activity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2016年第12期6卷 826-838页

作者： Marcel Gahamanyi Jean Marie Ntaganda mahamat saleh Daoussa Haggar Department of Mathematics College of Science and Technology School of Science University of Rwanda Kigali Rwanda Department of Applied Mathematics N’djamena University N’djamena Chad

In this paper, we aim to solve a two compartmental mathematical model of ordinary differential equations for cardiovascular-respiratory system using a new recent method: Perturbation Iteration method. The description of this method for different order derivatives in the Taylor Series expansion is discussed. This method provides the solution in the form of an infinite series for ordinary differential equation. The efficiency of the method used is investigated by a comparison of Euler method and Runge Kutta. Numerical simulations of all these three methods are implemented in Matlab. The validation has been carried out by taking the values of determinant parameters of cardiovascular-respiratory system for a 30 years old woman who is supposed to make practice of three regular physical activities: Walking, Jogging and Running fast. The results are in good agreement with experimental data.

关键词： Perturbation-Iteration Method Glucose Insulin Heart Rate Alveolar Ventilation Physical Activity Numerical Simulation

Fuzzy Logic for Solving an Optimal Control Problem of Hypoxemic Hypoxia Tissue Blood Carbon Dioxide Exchange during Physical Activity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2014年第11期4卷 501-514页

作者： Jean Marie Ntaganda mahamat saleh Daoussa Haggar Benjamin Mampassi Department of Applied Mathematics School of Pure and Applied Sciences College of Science and Technology University of Rwanda Kigali Rwanda N’Djamena University N’Djamena Chad Cheikh Anta Diop University Dakar Senegal

This paper aims at using of an approach integrating the fuzzy logic strategy for hypoxemic hypoxia tissue blood carbon dioxide human optimal control problem. To test the efficiency of this strategy, the authors propose a numerical comparison with the direct method by taking the values of determinant parameters of cardiovascular-respiratory system for a 30 years old woman in jogging as her regular physical activity. The results are in good agreement with experimental data.

关键词： Fuzzy Logic Optimal Control Membership Function Membership Degree Hypoxemic-Hypoxia Pressure Carbon Dioxide Oxygen Numerical Simulation

Evaluation of the Strategy and Efficacy of Treatment of Chronic Viral Hepatitis C with the Sofosbuvir/Daclatasvir Combination in a Resource-Limited Country

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Gastroenterology 2024年第7期14卷 233-240页

作者： Mayanna Habkreo Ali mahamat Moussa Adama Ahmed Ngare Abdraman Kossou Tahir mahamat saleh Maire Dehainsala mahamat Ali Hachim mahamat Ali Bolti Oumaima Djarma Joseph Madtoingue Service de Gastroentrologie/Mdecine Interne du Centre Hospitalier Universitaire la Rfrence Nationale NDjamena Chad Service de Gastroentrologie du Centre Hospitalier Universitaire la Renaissance NDjamena Chad Service de Maladies Infectieuses du Centre Hospitalier Universitaire la Renaissance NDjamena Chad Service de Maladies Infectieuses du Centre Hospitalier Universitaire la Rfrence Nationale NDjamena Chad

Introduction: The treatment of viral hepatitis C (HCV), a major public health problem, has evolved considerably since the introduction of direct-acting anti-virals (DAAs). The aim of this study was to evaluate the strategy for initiating treatment with Sofosbuvir/Daclatasvir, and also to assess its efficacy. Patients and Methods: Included were patients aged at least 15 years, with detectable hepatitis C viremia and treated with a pan-genotypic Sofosbuvir/Daclatasvir regimen at the Centre “Hospitalier Universitaire la Référence Nationale de N’Djamena” between October 2019 and October 2023. The APRI score was used to assess fibrosis. Cure was defined by an undetectable viral load 12 weeks after the end of treatment. Results: A total of 835 patients were included (sex ratio 1.55, mean age 50.5 ± 13.73, extremes 20 and 84 years). The 60 - 69 age group was the most represented. The mean APRI score was 0.42 ± 0.29, with extremes of 0.019 and 1.84. The mean viral load was 2,316,193.086 IU/mL. All subjects had good renal function. Cytolysis was absent in 70% of cases. Without genotyping, a pan-genotypic regimen was used in all patients: Sofosbuvir (400 mg)/Daclatasvir (60 mg). The cure rate was 99.4%, with good tolerability. However, four cases of failure were recorded out of the 668 patients who underwent follow-up HCV-PCR testing after 12 weeks of treatment. Conclusion: The Sofosbuvir/Daclatasvir regimen is highly effective, with an excellent safety profile. However, the still high cost of these molecules limits their accessibility to a large proportion of patients.

关键词： Efficacy Tolerance Sofosbuvir/Daclatasvir HCV Chad

Fuzzy Logic Strategy for Solving an Optimal Control Problem of Therapeutic Hepatitis C Virus Dynamics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2015年第9期5卷 527-541页

作者： Jean Marie Ntaganda mahamat saleh Daoussa Haggar Benjamin Mampassi College of Science and Technology School of Sciences Department of Mathematics University of Rwanda Butare Rwanda Department of Mathematics Faculty of Exact and Applied Sciences N’Djamena University N’Djamena Chad Department of Mathematics Faculty of Sciences and Technology Dakar University Dakar Senegal

This paper aims at the development of an approach integrating the fuzzy logic strategy for a therapeutic hepatitis C virus dynamics optimal control problem. To test the efficiency of this strategy, the authors propose a numerical comparison with the direct method by taking the values of determinant parameters of this disease for people administrating the drugs. The results are in good agreement with experimental data.

关键词： Fuzzy Logic Optimal Control Membership Function Membership Degree Hepatitis C Virus Uninfected Hepatocytes Infected Hepatocytes Numerical Simulation

Eradication Treatment of Helicobacter pylori Infection: Evaluation of Therapeutic Strategies in N’Djamena

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Gastroenterology 2024年第2期14卷 59-67页

作者： Mayanna Habkréo Ali mahamat Moussa Tahir mahamat saleh Djerabet Franckly Fany Haby Mairé Dehainssala Adama Ngaré mahamat Ali Hachim Service de Medecine Interne et Gastroenterologie Centre Hospitalier Universitaire La Reference Nationale N’Djamena Tchad Service de Medecine Interne Centre Hospitalier Universitaire La Renaissance N’Djamena Tchad Service de Médecine Hopital de l’Amitié Tchad-Chine N’Djamena Tchad

Background: Helicobacter pylori (Hp) infection is the most widespread bacterial infection in the world. The infection is generally acquired in childhood, but can persist into adulthood. Eradication therapy has undergone several modifications. The aim of this study was to evaluate the different therapeutic strategies used in the eradication of Helicobacter pylori infection in the Centre Hospitalier Universitaire La Reference Nationale of N’Djaména. Patients and Methods: This was a prospective, descriptive analytical study spread over one year, from September 2021 to September 2022. Patients at least 15 years of age presenting with dyspeptic symptoms, seen consecutively in a hepato-gastroenterology consultation and with a positive stool test for H. pylori infection, were included in the study. Equally, 1/3 of patients were treated with dual or triple therapy. The remaining third received quadritherapy. Results: A total of 268 patients were included in the study (mean age 38.40 ± 14.66 with extremes of 16 and 80 years). Males predominated in 58% of cases. Overall therapeutic efficacy was 88.9%. According to different therapeutic strategies, efficacy was 90.75% for dual therapy with PPI (Rabeprazole) and Amoxicillin. On the other hand, efficacy was 87% and 88.88% for PPI-based triple therapy and dual antibiotic therapy, and for PPI-based quadruple therapy and triple antibiotic therapy. Conclusion: H. pylori infection is a common disease in Chad. Dual therapy with rabeprazole combined with a high dose of amoxicillin over a period of at least two weeks showed similar if not better efficacy than triple or quadruple therapy.

关键词： Helicobacter pylori Therapeutic Strategies Eradication Dyspepsia Chad