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Vertical accuracy evaluation of freely available latest high-resolution(30 m)global digital elevation models over Cameroon(Central Africa)with GPS/leveling ground control points.

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International Journal of Digital Earth 2019年第5期12卷 500-524页

作者： Loudi Yap Ludovic Houetchak Kande Robert Nouayou Joseph Kamguia nasser abdou ngouh Marie Brigitte Makuate Research Laboratory in Geodesy National Institute of CartographyYaound3Cameroon Department of Physics Faculty of SciencesUniversity of Yaoundé1YaoundéCameroon

Digital Elevation Models(DEMs)contain topographic relief data that are vital for many geoscience *** study relies on the vertical accuracy of publicly available latest high-resolution(30 m)global DEMs over *** models are(1)the ALOS World 3D-30 m(AW3D30),(2)the Shuttle Radar Topography Mission 1 Arc-Second CBand Global DEM(SRTM 1)and(3)the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2(ASTER GDEM 2).After matching their coordinate systems and datums,the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global *** this,the three models are compared among them,in order to access random and systematic effects in the elevation data each of them ***,heights from 555 GPS/leveling points distributed all over Cameroon are compared to each DEM,for their vertical accuracy *** and robust statistical measures,normality test,outlier detection and removal were used to describe the vertical quality of the *** test of the normality rejected the hypothesis of normal distribution for all tested global *** vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square(RMS)and Normalized Median Absolute Deviation(NMAD)are:AW3D30(13.06 m and 7.75 m),SRTM 1(13.25 m and 7.41 m)and ASTER GDEM 2(18.87 m and 13.30 m).Other accuracy measures(MED,68.3% quantile,95% quantile)supply some evidence of the good quality of AW3D30 over ***,the effect of land cover and slope on DEM vertical accuracy was also *** models have proved to be worse in the areas dominated by forests and shrubs *** 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated *** dependency of DEMs accuracy on the terrain roughness is *** all slope intervals,AW3D30 is performing

关键词： DEM AW3D30 SRTM 1 ASTER GDEM 2 Cameroon GPS/leveling orthometric heights vertical accuracy

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Water Quality Assessment in the Bamoun Plateau, Western-Cameroon: Hydrogeochemical Modelling and Multivariate Statistical Analysis Approach

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Journal of Water Resource and Protection 2021年第2期13卷 112-138页

作者： Zakari Mfonka Amidou Kpoumié abdou nasser ngouh Oumar Farouk Mouncherou Daouda Nsangou Felaniaina Rakotondrabe Alain Fouépé Takounjou Mounira Zammouri Jules Rémy Ndam Ngoupayou Paul-Désiré Ndjigui Geosciences Natural Resources and Environment Laboratory Department of Earth Sciences Faculty of Science University of Douala Douala Cameroon Geosciences and Sustainable Development Laboratory Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroon National Institute of Cartography Ministry of Scientific Research and Innovation Yaoundé Cameroon Institute for Geological and Mining Research Ministry of Scientific Research and Innovation Yaoundé Cameroon Geosciences of Superficial Formations and Applications Laboratory Department of Earth Sciences Faculty of Science University of Yaoundé I Yaounde Cameroon Center of Water Research and Technologies Geo-Resources Laboratory Faculty of Science University of Tunis El Manar Tunis Tunisia

This study focuses on the geochemical and bacteriological investigation of surface and ground water in the Bamoun plateau (Western-Cameroon). During the period from September 2013 to August 2014, 71 samples were collected from two springs, one borehole, four wells and the Nchi stream for analysis of major elements. In order to obtain the characteristics of the various species of bacteria, 7 samples were selected. The analytical method adopted for this study is the conventional hydrochemical technic and multivariate statistical analysis, coupled with the hydrogeochemical modelling. The results revealed that, water from the zone under study are acidic to basic, very weakly to weakly mineralized. Four types of water were identified: 1) CaMg-HCO3;2) CaMg-Cl-SO4;3) NaCl-SO4 and 4) NaK-HCO3. The major elements were all listed in the World Health Organization guidelines for drinking water quality, except for nitrates which was found at a concentration > 50 mg /l NO-3 in the borehole F401. As for the hydrobiological aspect, the entire sample contained all the bacteriological species except for spring S301 and well P401. According to the hydrogeochemical modelling, the Gibbs model and multivariate statistical tests, the quality of surface and ground water of the Foumban locality is influenced by two important factors: 1) the natural factors characterized by the water-rock interaction, evapotranspiration/crystallization, 2) the anthropogenic factors such as: uncontrolled discharges of liquid and solid effluents of all kinds and without any prior treatment within the ground and the strong urbanization accompanied by lack of sanitation and insufficient care.

关键词： Foumban Surface and Ground Water Water-Rock Interaction Bacteriological Parameters Hierarchical Clustering Analysis Principal Component Analysis

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Wastewater Decontamination from Microorganisms by Electrospraying Corona Discharge

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Journal of Modern Physics 2013年第12期4卷 1632-1637页

作者： Mohamed Elsawah Mohamed Ali Safwat Hassaballah nasser Morgan Ahmed Samir Farouk Elakshar abdou Garamoon 1Center of Plasma Technology Al Azhar University Cairo Egypt 2Physics Department Faculty of Science Al-Azhar University Cairo Egypt Botany and Microbiology Department Faculty of Science Al-Azhar University Cairo Egypt Center of Plasma Technology Al Azhar University Cairo Egypt

A novel water treatment technique, based on a combination of electrospraying and pulsed corona discharge, has been used for bio-decontamination of wastewater. The electrospraying process has been found to increase the surface area of the treated wastewater, and hence increases the efficiency of the corona treatment process. The phase diagram of the discharge, which characterizes the discharge regimes, has been identified experimentally. The survival ratio of the microorganisms has been investigated experimentally as a function of the applied voltage and the numbers of treatment runs using air and oxygen as working gases. Microorganism surface has been examined using scanning electron microscope (SEM), which enabled in understanding the decontamination mechanisms of the treated microorganism. A complete decontamination has been achieved after only one run for an applied voltage higher than 16 kV when the discharge system was operated in oxygen gas. Optical emission spectrum of the electrosprayed water confirmed the existence of OH-radicals responsible for decontamination process.

关键词： Wastewater Decontamination Electrospraying Pulsed Corona Discharge Low Temperature Plasma for Biodecontaination Environmental Applications of Plasmas Wastewater Treatment

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Experimental Study of Electric and Spectroscopic Characteristics of Electric Discharge in LPG

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Journal of Modern Physics 2014年第15期5卷 1450-1458页

作者： Ahmed Abd Elradi nasser N. Morgan Sobhy Ghalab Mansour Elsabagh Safwat Hassaballa Ahmed Samir Farouk F. Elakshar abdou A. Garamoon Center of Plasma Technology Al Azhar University Cairo Egypt

Electric discharge has been carried out in LPG using DC high voltage (0.4 - 3 KV) at gas pressure in the range of 1 to 25 torr. The electric and spectroscopic characteristics of the discharge were studied at different discharge conditions. Deviations from Paschen’s law were observed as a result of the change of the distance between the two the electrodes. Two discharge modes, namely glow discharge and spark discharge modes, has been observed in the discharge current waveforms. The discharge current waveforms indicate a repetitive pulsed behaviour with frequencies of 5 kHz to 5 MHz depending upon the applied voltage and the gas pressure. The emitted spectra from the discharge are also studied near both the cathode and the anode using different electrode materials. Hα line and C2 Swan band system are observed, which confirms the conversion of LPG to hydrogen and carbon clusters.

关键词： Liquefied Petroleum Gas Electric Discharge Hydrogen Production Propane Decomposition Butane Decomposition

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Cardiac Amyloidosis: A Case Report of Seven Patients

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World Journal of Cardiovascular Diseases 2022年第3期12卷 160-167页

作者： Ngardjibem Djita Ibrahima Sory2 Sylla Aissatou Barry Murielle Ahodakin Djibril Sylla Elhadj Yaya Balde Mamadou Bachir Bah Houzeiph abdou Lassissi Alpha Kone Sana Soumra Mamadou Aliou Balde Mariame Beavogui Mamadou Dadhi Balde Noura Feniche Cardiology Department Alen&#231 on-Mamers Intercommunal Hospital Alen&#231 on France Gamal Abdel nasser University of Conakry Conakry Republic of Guinea

Introduction: Cardiac amyloidosis is a rare and under-diagnosed disease. The objective of this study was to collect cases of cardiac amyloidosis in patients hospitalized in the cardiology department of the Centre Hospitalier Intercommunal Alençon-Mamers (CHICAM). Patients and Methods: This was a retrospective descriptive study of the records of patients diagnosed with cardiac amyloidosis. The study took place in the cardiology department of the CHICAM over 12 months (from January 1, 2020 to December 31, 2020). We included the files of patients in whom the diagnosis of cardiac amyloidosis was confirmed on the basis of clinical, echocardiographic, biological, scintigraphic and cardiac MRI evidence. Results: Seven patients were included. The mean age was 86.71 years. Six men for one woman. Most of the patients were in heart failure. There was one case of periorbital ecchymosis. Troponinemia was increased in three patients, NTproBNP was always high with a mean of 1000 ng/L. Cardiac echography showed a hyperbright septum in four cases, concentric hypertrophy of the left ventricle with a mean interventricular septum in diastole of 13.85 mm. Six cases were senile transthyretin amyloidosis (TTR), one case was mutated transthyretin amyloidosis (TTRm). Two cases of death were noted. Conclusion: Cardiac amyloidosis has a poor prognosis due to delayed diagnosis.

关键词： Cardiac Amyloidosis Echocardiography Heart Failure Myocardial Scintigraphy

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Ultrasound Pulse Elastometry: Assessment of One Year’s Practice in the Hepato-Gastroenterology Department of the Saint Camille Hospital in Ouagadougou

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Open Journal of Gastroenterology 2024年第11期14卷 379-385页

作者： Kounpiélimé Sosthène Somda Lawagoulé Joseph Emile Ky Constant Lawrence Coudjo Johnson Stella Line Emmanuella Paré Ben Moctar abdou Djibo Toussaint Vébamba Abraham Ouédraogo Fanta Ousseini Mamadou Sarifou Diallo Sandrine M. O. B. Héma/Soudré Aboubacar Coulibaly Arsène Roger Sombié Department of Gastroenterology Yalgado Ouedraogo University Hospital Ouagadougou Burkina Faso Department of Medicine Joseph KI-ZERBO University Ouagadougou Burkina Faso Department of Gastroenterology Fada NGourma Regional Hospital Fada NGourma Burkina Faso Department of Gastroenterology Donka National Hospital Conakry Guinea Faculty of Health Sciences and Techniques Gamal Abdel Nasser University Conakry Guinea Department of Gastroenterology Tengandogo University Hospital Ouagadougou Burkina Faso

Aims: To review one year of ultrasound impulse elastometry in a hospital in Ouagadougou. Patients and Method: This is a retrospective descriptive study of data from one year’s use of impulse ultrasound elastometry. Ultrasound impulse elastometry was performed using the FibroScan® COMPACT 530. Fibrosis was considered significant when E (hepatic elasticity) ≥ 7.2 kPa (F2 fibrosis). The test was considered valid when the IQR/Median ratio ≤ 30% and there were at least 10 valid measurements. Results: A total of 1911 patients underwent FibroScan®. There were 1079 men, giving a sex ratio of 1.3. The mean age of the patients was 37.9 ± 12.2 years. The indication for FibroScan® was hepatitis B virus infection in 89% of cases. The validation criteria for FibroScan® were met in all patients. The mean value for elasticity was 7.9 kPa and for steatosis 212 dB/m. Fibrosis was non-significant in 75.5% of cases. More than half of our patients (56.7%) didn’t have steatosis, 24.8% had mild steatosis, 12.4% had moderate steatosis and 6.1% had severe steatosis. Conclusion: Ultrasound pulse elastometry plays an important role in monitoring chronic liver disease. It allows non-invasive diagnosis of hepatic fibrosis and steatosis. In our context, however, access to the test is limited by its availability only in large urban centers, and by its cost.

关键词： Pulse Elastometry Hepatic Fibrosis Steatosis Non-Invasive Evaluation of Fibrosis Africa

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