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Search Results: 1 - 10 of 301 matches for " Ndeye Yacine Badiane Ndour "
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Effect of the Continuum Removal in Predicting Soil Organic Carbon with Near Infrared Spectroscopy (NIRS) in the Senegal Sahelian Soils  [PDF]
Macoumba Loum, Mateugue Diack, Ndeye Yacine Badiane Ndour, Dominique Masse
Open Journal of Soil Science (OJSS) , 2016, DOI: 10.4236/ojss.2016.69014
Abstract: Spectroscopy plays a major role in the access of the analytical parameters of the soil. It tends to substitute the conventional laboratory analysis because hyperspectral data were least expensive and easier to obtain. The objective of this study was to evaluate the effect of the continuum removal (CR) in the validation of the accurate prediction model of the soil properties with Vis-NIR spectroscopy data. Few studies using Vis-NIR reflectance spectroscopy have well focused the calculation of the CR method; its effect in the calibration of the accurate models was also not well emphasized. In this study, we used the remote sensing software ENVI 4.7 to compute the CR function where the value of the continuum for each sample and for each spectral wavelength was obtained by dividing the reflectance values of the full spectrum (FS) with those of the continuum curve (CC). The partial least square regression (PLSR) model was applied in the spectral data from the soil of the Senegal Sahelian region. It was calibrated with both data from the full spectrum (FS) and those obtained after the application of the continuum removal. With the application of the CR, ultraviolet wavelengths (350 - 429 nm) and those of near infrared (2491 - 2500 nm) were removed from the explanatory variables of PLSR model. With the FS, all wavelengths between 350 and 2500 nm were taken into account in predicting soil properties. Our findings show a positive effect of the application of CR in the estimation of soil organic carbon. In calibration, the R2 increased up to 10% with the continuum removal in the model of 12 components (CP). In terms of validation, it’s the 15-component model which is the most accurate with the same range in calibration between the FS and the CR. The lowest RMSE ranged from 0.04 with the FS to 0.03 with the application of the CR in calibration and validation. These results show that the interest of this study as soil organic carbon is recognized as a key indicator of fertility of the soil in Sahelian-African regions. For future studies, it’s important to apply the model of neural networks to better evaluate the effect of continuum removal in predicting soil properties from the spectral data and other methods of preprocessing like the multiplicative scatter correction (msc).
Effects of different inputs of organic matter on the response of plant production to a soil water stress in Sahelian region  [PDF]
Abdoulaye Badiane, Ndeye Yacine Badiane Ndour, Fatou Guèye, Saliou Faye, Ibrahima Ndoye, Dominique Masse
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.412125
Abstract: The aim was to study the effects of organic management like the application of organic matters on crop production. This research is placed in the context of climate change impact mitigation. A field experiment was conducted during the dry season. Rainfall inputs were simulated by irrigation to study the effects of water stress during the flowering period of a grain on the agronomic and the physiological behavior of the plant. The measurements were made on the volumetric soil moisture, stomatal conductance, and leaf area index (LAI), grain yield, straw and weight of 100 grains. The water use efficiency (WUE) and yield losses were evaluated. The results of the volumetric soil moisture showed that the use of localized input under water stress (STR-T1) recorded the lowest moisture in the surface horizons. Treatment with localized input under water stress with or without fertilization (STR-T1, STR-T1 + N) showed an ability of stomatal regulation compared to the control (STR- T0) and the input application by spreading (STR- T2). (STR-T1 + N) has initiated an early stomatal closure of the plant because of the effect of nitrogen. However, despite a more pronounced water stress with stomatal closure, the LAI and the grain yield were greater with (STR-T1) and (STR-T1 + N). The results showed that the inputs of localized organic fertilization with or without nitrogen grain yields were the highest regardless of the hydric regime applied. However the losses of grain yield were higher in treatments with organic inputs in spreading and localized under water stress. The WUE by the crop was reduced compared to the control with organic inputs under STR. In this study we show that the use of organic matter increases de farmers risk and this notion of risk is high and it is necessary to consider this risk in the proposals of technical innovations.
Impact of Simulated Drought Stress on Soil Microbiology, and Nematofauna in a Native Shrub + Millet Intercropping System in Senegal  [PDF]
Sidy Diakhaté, Ndeye-Yacine Badiane-Ndour, Hassna Founoune-Mboup, Sally Diatta, Abdoulaye Fofana Fall, Rebecca R. Hernandez, Laurent Cournac, Richard Dick, Lydie Chapuis-Lardy
Open Journal of Soil Science (OJSS) , 2016, DOI: 10.4236/ojss.2016.612018
Abstract: Drought stress strongly affects soil biota and impairs crop production, which under climate change will be exacerbated in semi-arid cropping regions such as the Sahel. Hence soil management systems are needed that can buffer against drought. In West Africa, field studies have found intercropping of millet with the native shrub Piliostigma reticulatum improves soil-plant-water relations, microbial activity and diversity, and suppress parasitic nematodes, which can significantly increase crop yield. However, little information is available on its beneficial or negative effects on soils or crops during water stress. Therefore, the objective was to investigate the impact of P. reticulatum in moderating water stress effects on soil properties and pearl millet (Pennisetum glaucum [L.] R. Br.) productivity. In the greenhouse, soil chemical and microbial properties and millet growth were investigated with a factorial experiment of varying levels of soil moisture (favorable, moderately stressed, or severely stressed water conditions) that was imposed for 55 days on soils containing sole P. reticulatum or millet, or millet + P. reticulatum. The results showed that the presence of P. reticulatum did not buffer soils against water stress in relation to soil chemical and microbial properties measured at the end of the experiment. Severe water stress did significantly decrease the height, number of leaves, and aboveground biomass of millet plants. Additionally, respiration, nematofauna trophic structure and abundance decreased as water stress increased. Lastly, bacterial feeders and plant parasitic nematodes were the most sensitive to severe water stress while fungal feeding nematodes remained unaffected. The results suggested that the intensity of water stress had more negative effects on soil basal respiration rather than soil microbial biomass.
Prevalence of Hypertension and Associated Factors in Patients Living with HIV Followed at the Ambulatory Treatment Center (CTA) of Fann National University Hospital in Dakar  [PDF]
Ndeye Fatou Ngom Gueye, Daye Ka, Alioune Badara Tall, Kine Ndiaye, Abdoul Aziz Ndiaye, Viviane Marie Pierre Cisse, Aissata Guindo, Ndeye Méry Dia Badiane, Sylvie Audrey Diop, Noel Magloire Manga, Cheikh Tidiane Ndour, Moussa Seydi
Health (Health) , 2017, DOI: 10.4236/health.2017.94052
Introduction: The efficacy of antiretroviral therapy in people living with HIV (PLHIV) has been associated with an important increase in metabolic disorders, such as hypertension (HTA). This work allowed us to estimate the prevalence of hypertension in PLHIV and to describe associated factors. Methods: A retrospective, descriptive and analytical study was carried out based on the records of people living with HIV followed at the Ambulatory Treatment Center (CTA), from January 1st 1998 to 31st, December 2014. The WHO criteria were used to diagnose hypertension. Data entry was performed using ESOPE software and data analysis was done using Epi Info software version 3.5.3. A multiple logistic regression was used to identify the risk factors associated with hypertension. Results: During the study period, 3624 patients followed at CTA were included of which 1184 patients (32.7%) had hypertension. The average age was 47. 3 years ±10.5 years, with a sex ratio of 0.7. The most common opportunistic infections at diagnosis were tuberculosis (14.9%) and oral candidiasis (15.3%). The HIV infection was advanced (stage 3 or 4 of WHO classification) for 39% of cases. Overweight and obesity was found in 19.1%. Only 17.6% were treated by protease inhibitors. Higher average age (OR:1,05; IC [1.04 - 1.05], p = 0.000001), higher average BMI (OR:5,3; IC [3.3 - 8.5], p = 0.00001), WHO clinical stage I-II (OR:1,4; IC [1.2 - 1.6], p = 0.00003), and ARV treatment (OR:2,5; IC [1.7 - 3.7], p = 0.000001) are associated with the occurrence of hypertension. Conclusion: The prevalence of hypertension was high among PLHIV and associated factors were: advanced age, high BMI, WHO clinical stages I and II and antiretroviral therapy. Hence, the interest of a systematic screening of hypertension and others cardiovascular risk factors particularly in patients under ARV antiretroviral therapy.
Assessment of Climate Trends and Land Cover/Use Dynamics within the Somone River Basin, Senegal  [PDF]
Ndeye Yacine Barry, Vieux Boukhaly Traore, Mamadou Lamine Ndiaye, Osemwegie Isimemen, Hauhouot Celestin, Bienvenu Sambou
American Journal of Climate Change (AJCC) , 2017, DOI: 10.4236/ajcc.2017.63026
Abstract: This study was undertaken mainly to 1) investigate temporal trends in annual rainfall and temperature; 2) identify discontinuities in the time series; and 3) assess the Land Use/Land Cover Change (LULC) in the Somone coastal lagoon, within the river basin. The study examined temporal trends in rainfall (1931-2016) and temperature (1961-2016) datasets of Somone river basin, and breaks in time series using Mann-Kendall non-parametric test and other suitable statistical tools. Temporal evolution in LULC was assessed for the years 1954, 1978, 2003 and 2016. Analysis indicates a significant decreasing trend in precipitation over the basin. These trends are much more pronounced for minimum and average rainfall than for maximum and annual amplitudes. Contrary to precipitation, surface air temperature shows a significant increasing trend for its minimum and averages, and a decreasing trend for its maximum and amplitudes. A significant break in precipitation was observed in 1958, while surface air temperature presents much longer breaks within the years 1975 and 1977, and 1991 and 1993. A more direct implication of climate change on LULC patterns is increased in unproductive salt pans (Sabkhas). Increase in Sabkhas gave rise to conversion of forest lands to agricultural lands of local farmers in search for fertile soils to cater for the food needs of a growing population. Otherwise, the development of the settlements, favored by the tourism activity and agriculture crisis, is another cause of croplands decreasing. The findings of the present research clearly indicate that the impacts of climate change are exacerbated by rapid urbanization in the basin.
Prevalence and Factors Associated with Virologic Failure among People Living with HIV (PLHIV) Monitored in a Decentralized Health Care Facility  [PDF]
Selly Ba, Ndeye Diama Ba, Lamanatou Sembene, Habibatou Dia, Mohamed Coulibaly, Jean Louis Ndiaye, Ndeye Méry Dia, Cheikh Tidiane Ndour
Advances in Infectious Diseases (AID) , 2019, DOI: 10.4236/aid.2019.93016
Abstract: Introduction: In Senegal, the decentralization of Health Care Centers has contributed significantly to the intensification of antiretroviral treatment. However, Care providers are still facing the treatment optimizing challenge. Objectives: To determine the prevalence of virologic failures of PLHIV monitored in a decentralized Health care center and to determine associated factors. Patients and Methods: This is a cross-sectional descriptive and analytical study of PLHIV, aged 18 years and over, on first-line treatment, monitored onsite from February 1st to December 31st, 2018. A data collection form was completed from medical records (clinical, immuno-virologic and evolutionary). Any VL > 1000 cp/ml after 6 months of antiretroviral therapy (ART) was considered as virologic failure. Data were captured and analysed using the EPI INFO 2002software. Chi-square test and the Fisher test were used to compare the proportions; a value of p ≤ 0.05 was considered significant. Results: 331 patients were treated with HIV-1 profile in 89% of cases. A proportion of 55% was married and 97% came from rural areas. 80% were either not or poorly educated. The median of age was 44 ± 11 years with a F/M ratio of 3.4. At baseline, 56% were symptomatic at stage 3 or 4 of WHO. They had severe immunosuppression with a median CD4 count of 217 ± 187 cells/mm3, the viral load was detectable in half of the patients with a median VL of 97,000 cp/ml ± 70,569. The antiretroviral regimen combined 2 NRTIs with 1 NNRTI in 88% of cases. The median of follow-up was estimated at 60 ± 43 months. The prevalence of virologic failure was 19%. This prevalence was associated with age less than 25 years (p = 0.04), late diagnosis (CD4 at baseline less than 200 cel/mm3 (p = 0.002), stage 3 or 4 WHO (p = 0.04) High viral load greater than 10,000 (p = 0.04) at baseline. Conclusion: These results suggest making the new therapeutic classes accessible for first-line treatment.
Characteristics of Liver Abscess in Department of Infectious Diseases at Fann Teaching University Hospital in Dakar, Senegal  [PDF]
Viviane Marie Pierre Cisse Diallo, Louise Fortes Déguénonvo, No?l Magloire Manga, Daye Ka, Sylvie Audrey Diop, Abdoulaye Seck, Ndèye Aissatou Lakhe, Khardiata Diallo Mbaye, Assane Diouf, Ndèye Méry Dia Badiane, Ndèye Fatou Ngom Guèye, Cheikh Tacko Diop, Masserigne Soumaré, Cheikh Tidiane Ndour, Moussa Seydi
Advances in Infectious Diseases (AID) , 2018, DOI: 10.4236/aid.2018.81004
Abstract: Introduction: Abscesses of the liver are due to an infection of bacterial, parasitic or fungal origin. Through amoebiological imaging and serology, their diagnosis was facilitated. The aim of this study was to determine the epidemiological, clinical, diagnostic and evolutionary aspects of these liver abscesses at the Department of Infectious and Tropical Diseases in Fann Teaching University Hospital. Patients and Methods: This was a retrospective and descriptive study, based on records of patients hospitalized for abscess of the liver over a period of 8 years, from January 1, 2008 to December 31, 2015. Results: We collected 20 cases of abscesses including 12 cases of confirmed amoebic abscesses and 5 cases of pyogenic abscesses. The mean age of the patients was 43.15 ± 15.12 years. There were 18 men and 2 women. The average hospital stay was 32 days. The most common clinical signs were abdominal pain (100%), fever (75%), hepatomegaly (80%). A leukocytosis greater than 12,000 Gb/mm3 was found in 13 patients. The amoebic serology was positive in 71% of cases and negative in 29% of cases. No germ was isolated from the blood culture. On hepatic ultrasound the abscess was unique in 90%. Treatment was exclusively medical in 11 patients (55%). The trend was favorable in 85% of cases. Conclusion: The incidence of liver abscesses has significantly decreased. It is important to develop diagnostic tools better in the case of pyogenic abscesses.
Incidence and Factors Associated with the Switch to the Second Line Antiretroviral Treatment at the Ambulatory Treatment Center (CTA) in Dakar  [PDF]
Ndeye Fatou Ngom-Gueye, Gilbert Batista, Abdoul Aziz Ndiaye, Assane Diouf, KA. Daye, Alioune Badara Tall, Awa Diouf, Kine Ndiaye, Makhtar Ndiaga Diop, Mountaga Dia, Cheikh Tacko Diop, Awa Gaye, Cheikh Tidiane Ndour, Moussa Seydi, Lamine Gueye, Bernard Marcel Diop, Papa Salif Sow
Health (Health) , 2016, DOI: 10.4236/health.2016.814154
Abstract: Introduction: Over the past years, efforts have been made to expand access to antiretroviral combinations (cART) in low-income countries. However, major concerns are noted with drug resistance emergence, as treatment failure result and need to introduce a second line treatment, more expensive and difficult to implement. The objective was to study the incidence of switch to second line, reasons for switch and risk factors using a cohort of people living with HIV in an Ambulatory Treatment Center in Dakar. Methodology: This was a cohort study of people living with HIV under cART from January 2004 to December 2013. Naive patients monitored for at least six months, regardless of their profile and regimen with baseline CD4 counts < 350 cells/mm3 were included in this study. Results: The median age of the 827 patients included was 44 [IQR = 18 - 78]. The switch to second-line treatment was observed in 72 patients (8.7%) after an average of 38.5 months of follow-up. The overall incidence rate of switch to second line of antiretroviral treatment was 1.59 per 100 persons-years. Most of changes in first-line treatment were motivated by virological failures (n = 60, 83.3%) under treatment with AZT/3TC/NVP (n = 25, 34.7%) or AZT/3TC/EFV21 (29.2%). 9.7% of switch occurred after immunological failure, 1.4% after clinical failure, 4.2% after severe toxicity and 1.4% was not documented. Predictive factors identifying failures at the end of the multivariate analysis were age < 44 years and CD4 counts below 100 cells/mm3. Conclusions: In total, CTA identified a low incidence rate of treatment failure of the first line of treatment. Associated risk factors were age < 44 years, CD4 counts below 100 cells/mm3 and high viral load at treatment initiation.
HIV-2 Integrase Variation in Integrase Inhibitor-Na?ve Adults in Senegal, West Africa
Geoffrey S. Gottlieb, Robert A. Smith, Ndeye Mery Dia Badiane, Selly Ba, Stephen E. Hawes, Macoumba Toure, Alison K. Starling, Fatou Traore, Fatima Sall, Stephen L. Cherne, Joshua Stern, Kim G. Wong, Paul Lu, Moon Kim, Dana N. Raugi, Airin Lam, James I. Mullins, Nancy B. Kiviat, Papa Salif Sow 3 for the UW-Dakar HIV-2 Study Group
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0022204
Abstract: Background Antiretroviral therapy for HIV-2 infection is hampered by intrinsic resistance to many of the drugs used to treat HIV-1. Limited studies suggest that the integrase inhibitors (INIs) raltegravir and elvitegravir have potent activity against HIV-2 in culture and in infected patients. There is a paucity of data on genotypic variation in HIV-2 integrase that might confer intrinsic or transmitted INI resistance. Methods We PCR amplified and analyzed 122 HIV-2 integrase consensus sequences from 39 HIV-2–infected, INI-naive adults in Senegal, West Africa. We assessed genetic variation and canonical mutations known to confer INI-resistance in HIV-1. Results No amino acid-altering mutations were detected at sites known to be pivotal for INI resistance in HIV-1 (integrase positions 143, 148 and 155). Polymorphisms at several other HIV-1 INI resistance-associated sites were detected at positions 72, 95, 125, 154, 165, 201, 203, and 263 of the HIV-2 integrase protein. Conclusion Emerging genotypic and phenotypic data suggest that HIV-2 is susceptible to the new class of HIV integrase inhibitors. We hypothesize that intrinsic HIV-2 integrase variation at “secondary” HIV-1 INI-resistance sites may affect the genetic barrier to HIV-2 INI resistance. Further studies will be needed to assess INI efficacy as part of combination antiretroviral therapy in HIV-2–infected patients.
WENO Schemes for the Resolution of the Two-Dimensional Vlasov-Poisson System
Yacine Benhadid
International Journal of Applied Physics and Mathematics , 2013, DOI: 10.7763/ijapm.2013.v3.186
Abstract: A numerical resolution of the two dimensional Vlasov-Poisson system is proposed. The time splitting method is used on the Vlasov equations to reduce the dimensions, then we apply the WENO (weighted essentially non-oscillatory) scheme based on the idea of Harten to solve our equation. We elaborate a transformation time-space to avoid the mixed problem and reducing the error. This algorithm is applied to the two dimensional Vlasov-Poisson system and an evolution of the density and the total energy is presented
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