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Search Results: 1 - 10 of 401078 matches for " M. Mubiru "
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Correlation between sunshine hours and climatic parameters at four locations in Uganda
K Karume, EJKB Banda, J Mubiru, M Majaliwa
Tanzania Journal of Science , 2007,
Abstract: One of the most important factors in solar energy production is related to the predictability of sunshine hours. The objective of this study is to assess the correlation between sunshine hours and relative humidity, cloud cover, maximum and minimum temperature, for the purpose of identifying the most appropriate parameter(s) for the prediction of sunshine hours in Uganda. Climatic data for the meteorological stations of Entebbe, Mbarara, Tororo and Makerere, extending over a period of 15 years (1990-2005) was collected from the Department of Meteorology, Kampala. The data set included maximum temperature, minimum temperature, relative humidity at 6 am and at 12 noon, Cloud cover at 6 am and at 12 noon and Sunshine hours. A multiple regression technique was used to assess the correlation between sunshine hours and maximum and minimum temperatures, cloud cover at 6 am and at 12 noon and relative humidity at 6 am and at 12 noon. Results have shown that the availability of sunshine hours can be predicted by the use of maximum and minimum temperatures, relative humidity at 6 am and 12 noon and cloud cover at 6 am and at 12 noon in Uganda, but, principal components and factoraAnalysis have indicated that two parameters, especially relative humidity at noon or 6 am and Maximum temperature are enough to capture the variability of sunshine hours in Uganda.
Using Artificial Neural Networks to Predict Direct Solar Irradiation
James Mubiru
Advances in Artificial Neural Systems , 2011, DOI: 10.1155/2011/142054
Abstract: This paper explores the possibility of developing a prediction model using artificial neural networks (ANNs), which could be used to estimate monthly average daily direct solar radiation for locations in Uganda. Direct solar radiation is a component of the global solar radiation and is quite significant in the performance assessment of various solar energy applications. Results from the paper have shown good agreement between the estimated and measured values of direct solar irradiation. A correlation coefficient of 0.998 was obtained with mean bias error of 0.005 MJ/m2 and root mean square error of 0.197?MJ/m2. The comparison between the ANN and empirical model emphasized the superiority of the proposed ANN prediction model. The application of the proposed ANN model can be extended to other locations with similar climate and terrain. 1. Introduction Much of the work of the prediction of solar radiation has been the estimation of global solar radiation, yet data of the two main components (direct and diffuse) of global solar radiation are equally important. These components are required in a variety of applications such as in thermal analyses and crop models. There is need to estimate these components in the absence of measured values. Some authors such as Davies and McKay [1] and Gueymard [2] have used radiative transfer models in the estimation of direct solar irradiance. Such models take into account interactions between the direct solar irradiance and terrestrial atmosphere. The problem with the use of such models is the unavailability of some of the atmospheric information needed. Simpler models that relate direct solar irradiance with global irradiance have been developed by Vignola and McDaniels [3] and Louche et al. [4]. Other empirical models have been used to predict solar radiation by Majumdar et al. [5] in relation to surface humidity and absolute air mass; accuracy of prediction has been found to be ±10% with 95% confidence limits. Al-Mohamad [6] has calculated empirically direct solar radiation as one of the solar radiation components giving a relative percentage error in the range of ±3% between the calculated and actual values. Benson et al. [7] have derived daily and monthly regressions for direct solar radiation as one of the solar radiation components, which relate to sunshine duration. However, the empirical approach has tended to assume linearity in the prediction process. The uncertain nature of solar radiation and the modeling abilities of artificial neural networks (ANNs) have inspired the application of ANN techniques to predict
Growth, immune and viral responses in HIV infected African children receiving highly active antiretroviral therapy: a prospective cohort study
Philippa M Musoke, Peter Mudiope, Linda N Barlow-Mosha, Patrick Ajuna, Danstan Bagenda, Michael M Mubiru, Thorkild Tylleskar, Mary G Fowler
BMC Pediatrics , 2010, DOI: 10.1186/1471-2431-10-56
Abstract: A prospective cohort of HIV infected children were initiated on HAART and followed for 48 weeks. Body mass index for age z scores(BAZ), weight and height-for-age z scores (WAZ & HAZ) were calculated: CD4 cell % and HIV-1 RNA were measured at baseline and every 12 weeks. Treatment outcomes were classified according to; both virological and immunological success (VS/IS), virological failure and immunological success (VF/IS). virological success and immunological failure (VS/IF) and both virological and immunological failure (VF/IF).From March 2004 until May 2006, 124 HIV infected children were initiated on HAART. The median age (IQR) was 5.0 years (2.1 - 7.0) and 49% (61/124) were female. The median [95% confidence interval (CI)] BAZ, WAZ and HAZ at baseline were 0.29 (-2.9, -1.2), -1.2 (-2.1, -0.5) and -2.06 (-2.9, -1.2) respectively. Baseline median CD4 cell % and log10 HIV-1 RNA were; 11.8% (7.5-18.0) and 5.6 (5.2-5.8) copies/ml. By 48 weeks, mean WAZ and HAZ in the VF/IS group, which was younger, increased from - 0.98 (SD 1.7) to + 1.22 (SD 1.2) and from -1.99 (1.7) to + 0.76 (2.4) respectively. Mean increase in WAZ and HAZ in the VS/IF group, an older group was modest, from -1.84 (1.3) to - 0.41 (1.2) and -2.25 (1.2) to -1.16 (1.3) respectively. Baseline CD4 cell % [OR 6.97 95% CI (2.6 -18.6)], age [OR 4.6 95% CI (1.14 -19.1)] and WHO clinical stage [OR 3.5 95%CI (1.05 -12.7)] were associated with successful treatment outcome.HIV infected Ugandan children demonstrated a robust increase in height and weight z scores during the first 48 weeks of HAART, including those who failed to completely suppress virus. Older children initiating HAART with severe immune suppression were less likely to achieve a successful treatment outcome. These data emphasize the importance of initiating HAART early to ensure adequate immune and growth responses.Growth failure is a well recognized complication of HIV infection in children which can present as stunting, weight loss, failure t
Predicting Global Solar Radiation Using an Artificial Neural Network Single-Parameter Model
Karoro Angela,Ssenyonga Taddeo,Mubiru James
Advances in Artificial Neural Systems , 2011, DOI: 10.1155/2011/751908
Abstract: We used five years of global solar radiation data to estimate the monthly average of daily global solar irradiation on a horizontal surface based on a single parameter, sunshine hours, using the artificial neural network method. The station under the study is located in Kampala, Uganda at a latitude of 0.19°N, a longitude of 32.34°E, and an altitude of 1200?m above sea level. The five-year data was split into two parts in 2003–2006 and 2007-2008; the first part was used for training, and the latter was used for testing the neural network. Amongst the models tested, the feed-forward back-propagation network with one hidden layer (65 neurons) and with the tangent sigmoid as the transfer function emerged as the more appropriate model. Results obtained using the proposed model showed good agreement between the estimated and actual values of global solar irradiation. A correlation coefficient of 0.963 was obtained with a mean bias error of 0.055?MJ/m2 and a root mean square error of 0.521?MJ/m2. The single-parameter ANN model shows promise for estimating global solar irradiation at places where monitoring stations are not established and stations where we have one common parameter (sunshine hours). 1. Introduction Solar energy is energy from the Sun and is a vital resource to plant and human life on the Earth’s surface. Plants need solar energy in photosynthetic processes leading to plant growth. Human beings benefit indirectly through consumption of the plants. More so, solar energy determines climate changes which in turn affect natural processes on and under the Earth’s surface. The solar energy can be utilized directly through drying of foodstuffs and heating of water for home and commercial consumption. Indirect use of this energy resource is evident in generation of electricity using photovoltaic systems. The aforementioned solar applications need to be properly sized to meet the user’s requirements. Further, there may be a need to evaluate the performance of these applications and carry out specialized analysis, say, in plant growth studies. Solar radiation is a critical input parameter in these analyses [1]. All this requires knowledge of distribution of solar energy; hence, there is a need for availability of solar radiation data. This data can be measured or estimated from appropriate models. In developing countries such as Uganda, solar radiation data is scarce due to the high costs involved in buying and maintaining solar measuring equipment. Due to this fact, the long-term global solar radiation data is measured in very few locations where the
Characterising agrometeorological climate risks and uncertainties: Crop production in Uganda
Drake N. Mubiru,Everline Komutunga,Ambrose Agona,Anne Apok
South African Journal of Science , 2012, DOI: 10.4102/sajs.v108i3/4.470
Abstract: Uganda is vulnerable to climate change as most of its agriculture is rain-fed; agriculture is also the backbone of the economy, and the livelihoods of many people depend upon it. Variability in rainfall may be reflected in the productivity of agricultural systems and pronounced variability may result in adverse impacts on productivity. It is therefore imperative to generate agronomically relevant seasonal rainfall and temperature characteristics to guide decision-making. In this study, historical data sets of daily rainfall and temperature were analysed to generate seasonal characteristics based on monthly and annual timescales. The results show that variability in rainfall onset dates across Uganda is greater than the variability in withdrawal dates. Consequently, even when rains start late, withdrawal is timely, thus making the growing season shorter. During the March–May rainy season, the number of rainy days during this critical period of crop growth is decreasing, which possibly means that crops grown in this season are prone to climatic risks and therefore in need of appropriate adaptation measures. A time-series analysis of the maximum daily temperature clearly revealed an increase in temperature, with the lower limits of the ranges of daily maximums increasing faster than the upper limits. Finally, this study has generated information on seasonal rainfall characteristics that will be vital in exploiting the possibilities offered by climatic variability and also offers opportunities for adapting to seasonal distribution so as to improve and stabilise crop yields.
Factors Determining Survival and Retention among HIV-Infected Children and Adolescents in a Community Home-Based Care and a Facility-Based Family-Centred Approach in Kampala, Uganda: A Cohort Study
W. Massavon,L. Barlow-Mosha,L. Mugenyi,W. McFarland,G. Gray,R. Lundin,P. Costenaro,M. M. Nannyonga,M. Penazzato,D. Bagenda,C. P. Namisi,D. Wabwire,M. Mubiru,S. Kironde,D. Bilardi,A. Mazza,M. G. Fowler,P. Musoke,C. Giaquinto
ISRN AIDS , 2014, DOI: 10.1155/2014/852489
Abstract: We describe factors determining retention and survival among HIV-infected children and adolescents engaged in two health care delivery models in Kampala, Uganda: one is a community home-based care (CHBC) and the other is a facility-based family-centred approach (FBFCA). This retrospective cohort study reviewed records from children aged from 0 to 18 years engaged in the two models from 2003 to 2010 focussing on retention/loss to follow-up, mortality, use of antiretroviral therapy (ART), and clinical characteristics. Kaplan Meier survival curves with log rank tests were used to describe and compare retention and survival. Overall, 1,623 children were included, 90.0% (1460/1623) from the CHBC. Children completed an average of 4.2 years of follow-up (maximum 7.7 years). Median age was 53 (IQR: 11–109) months at enrolment. In the CHBC, retention differed significantly between patients on ART and those not (log-rank test, adjusted, ). Comparing ART patients in both models, there was no significant difference in long-term survival (log-rank test, , adjusted, ), while retention was higher in the CHBC: 94.8% versus 84.7% in the FBFCA (log-rank test, , adjusted ). Irrespective of model of care, children receiving ART had better retention in care and survival. 1. Background Sub-Saharan Africa (SSA) is home to the vast majority of infants, children, and adolescents living with HIV and morbidity and mortality remain high [1–3]. For example, mortality among HIV-infected children has been measured at 4.3% per year in East Africa and 8.3% in West Africa [4, 5]. A recent meta-analysis conducted in SSA reported a higher risk of early death among perinatally infected children [6]. Studies have also shown that substantial proportions of children and adolescents initiate treatment in SSA with advanced disease (46.3%–72.0%) and comorbidities such as tuberculosis (TB) (5.7%–34.0%) and malnutrition (33%–54%) that tend to be associated with early mortality and poor clinical outcomes [7–10]. Significant child mortality can be averted if antiretroviral therapy (ART) is started early [11–14]. However, despite overwhelming evidence demonstrating the benefits of ART, in practice high mortality and poor retention persist among HIV-infected children and adolescents in care in the resource-limited settings of SSA. In addition to scarce resources for programmes for children, the situation is compounded by a combination of factors including late HIV diagnosis, missed opportunities to initiate ART, health care programmes not tailored to the needs of the infected child and their family,
Long Delays and Missed Opportunities in Diagnosing Smear-Positive Pulmonary Tuberculosis in Kampala, Uganda: A Cross-Sectional Study
Ibrahim Sendagire,Maarten Schim Van der Loeff,Mesach Mubiru,Joseph Konde-Lule,Frank Cobelens
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014459
Abstract: Early detection and treatment of tuberculosis cases are the hallmark of successful tuberculosis control. We conducted a cross-sectional study at public primary health facilities in Kampala city, Uganda to quantify diagnostic delay among pulmonary tuberculosis (PTB) patients, assess associated factors, and describe trajectories of patients' health care seeking.
Low HIV testing rates among tuberculosis patients in Kampala, Uganda
Ibrahim Sendagire, Imke Schreuder, Mesach Mubiru, Maarten van der Loeff, Frank Cobelens, Joseph Konde-Lule
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-177
Abstract: Adult patients who had been diagnosed with smear-positive PTB at a primary care clinic or at the referral hospital and who were being treated at any of the three clinics were interviewed. Associations between having taken the test as the main outcome and explanatory variables were assessed by multivariate logistic regression.Between April and October 2007, 112 adults were included in the study. An HIV test had been offered to 74 (66%). Of the 112 patients, 61 (82%) had accepted the test; 45 (74%) had eventually been tested; and 32 (29%) had received their test results.Patients who were <25 yeas old, female or unemployed, or had reported no previous HIV testing, were more likely to have been tested. The strongest predictor of having been tested was if patients had been diagnosed at the referral hospital compared to the city clinic (adjusted OR 24.2; 95% CI 6.7-87.7; p < 0.001). This primarily reflected an "opt-out" (uptake 94%) versus an "opt-in" (uptake 53%) testing policy.The overall HIV test uptake was surprisingly low at 40%. The HIV test uptake was significantly higher among TB patients who were identified at hospital, among females and in the unemployed.Testing all patients routinely for HIV in settings with generalized HIV epidemics has the benefit of diagnosing the infection early and thereby preventing morbidity, mortality and sustained transmission through initiating prophylaxis and timely antiretroviral treatment (ART) [1-4]. Test uptake varies considerably from 12% to 98% across different settings and patients categories, but particularly with the testing approach used [5-8]. HIV test uptake levels of 12-62% have been reported when the test is offered using an "opt-in" approach [7,8], i.e. when patients are not tested unless they specifically request to. Uptake tends to be much higher (70-98%) when the HIV test is offered using an "opt-out" (or "provider-initiated") approach by which the HIV test is considered an integral part of the diagnostic procedures
The long-term effectiveness of generic adult fixed-dose combination antiretroviral therapy for HIV-infected Ugandan children
LN Barlow-Mosha, DS Bagenda, PK Mudiope, MC Mubiru, LM Butler, MG Fowler, PM Musoke
African Health Sciences , 2012,
Abstract: Background: Access to pediatric antiretroviral formulations is increasing in resource-limited countries, however adult FDCs are still commonly used by antiretroviral therapy (ART) programs. Objective: To describe long-term effectiveness of using adult FDC of d4T+3TC+NVP (Triomune) in children for HIV treatment. Methods: Clinical, immunologic, and virologic outcomes of HIV-infected ART-na ve children aged six months to 12 years, were evaluated up to 96 weeks post-ART initiation. Results: From March 2004 to June 2006, 104 children were followed with a median age of 5.4 years, median CD4 cell percent and HIV-1 RNA were 11.0% (IQR 6.7-13.9) and 348,846copies/mL (IQR 160,941-681,313) respectively at baseline. Using Kaplan-Meir estimates, 75% of children had undetectable viral loads (<400copies/mL) at 96weeks of ART. Children with a baseline CD4 cell percent >15% were 3 times more likely to achieve viral load <400copies/mL than those with baseline CD4 cell percent <5% after adjusting for baseline age {aHR = 3.03 (1.10-8.32), p=0.03}; no difference was found among those with CD4 cell percent >5-14.9% and <5%. Conclusion: Treatment with generic adult FDC for HIV-infected Ugandan children led to sustained clinical, immunologic and virologic response during 96 weeks of ART. Early initiation of ART is key to achieving virological success.
Analysis of Prostate-Specific Antigen Transcripts in Chimpanzees, Cynomolgus Monkeys, Baboons, and African Green Monkeys
James N. Mubiru, Alice S. Yang, Christian Olsen, Sudhir Nayak, Carolina B. Livi, Edward J. Dick, Michael Owston, Magdalena Garcia-Forey, Robert E. Shade, Jeffrey Rogers
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094522
Abstract: The function of prostate-specific antigen (PSA) is to liquefy the semen coagulum so that the released sperm can fuse with the ovum. Fifteen spliced variants of the PSA gene have been reported in humans, but little is known about alternative splicing in nonhuman primates. Positive selection has been reported in sex- and reproductive-related genes from sea urchins to Drosophila to humans; however, there are few studies of adaptive evolution of the PSA gene. Here, using polymerase chain reaction (PCR) product cloning and sequencing, we study PSA transcript variant heterogeneity in the prostates of chimpanzees (Pan troglodytes), cynomolgus monkeys (Macaca fascicularis), baboons (Papio hamadryas anubis), and African green monkeys (Chlorocebus aethiops). Six PSA variants were identified in the chimpanzee prostate, but only two variants were found in cynomolgus monkeys, baboons, and African green monkeys. In the chimpanzee the full-length transcript is expressed at the same magnitude as the transcripts that retain intron 3. We have found previously unidentified splice variants of the PSA gene, some of which might be linked to disease conditions. Selection on the PSA gene was studied in 11 primate species by computational methods using the sequences reported here for African green monkey, cynomolgus monkey, baboon, and chimpanzee and other sequences available in public databases. A codon-based analysis (dN/dS) of the PSA gene identified potential adaptive evolution at five residue sites (Arg45, Lys70, Gln144, Pro189, and Thr203).
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