Faculty of Science (FSC)

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Open Access
Performance of Household Water Treatment Methods for Microbial Removal under Household Conditions in Kabale District, Uganda
(Omega Publishers, 2016) Alex, Saturday; George Lukoye Makokha; Anthony Macharia
Despite the Ugandan government efforts to improve access to safe water sources, the rate at which diseases spread as a result of unsafe drinking water is absolutely high. The purpose the study was to assess the performance of household water treatment methods (HWT) and evaluate their ability to improve the microbial quality of drinking water under household conditions in Kabale District. We randomly selected 205 households, where we collected treated and untreated water samples. We analyzed 46 paired samples (untreated and treated) of drinking water from 46 households that reported treated water available. Samples were analyzed for total coliforms and Escherichia coli, the major indicators of biological contamination of drinking water, to measure effectiveness of treatment under household conditions. All reported HWT did not significantly improve the microbial quality of drinking water. Mean log10 total coliforms removal were 0.7 log10 (40.1%) for boiling method, 0.2 log10 (23.7%) for biosand filtration method, -0.01log10 (-18.1%) for let it stand and settle method and 0.1 log10 (16%) for application of aqua safe tablets. In addition, mean log10 Escherichia coli removal were 0.7 log10 (-22.6) for boiling method, 0.3log10 (37.5%) for biosand filtration method, -0.4 log10 (-200%) for let it stand and settle method and 0.6 log10 (50%) for application of aqua safe. The microbiological quality of stored treated drinking water was significantly low. The government should sensitize the local people on safe storage of drinking water.
Open Access
Household Water Treatment Technologies for Microbial Removal in Kabale District, Southwestern Uganda
(OMMEGA Publishers, 2016) Alex, Saturday; George Lukoye Makokha; Anthony Macharia
Health problems associated with the consumption of untreated drinking water is one of the greatest concerns in Kabale District in spite of government’s efforts to provide safe drinking water to the people. The objective of the study was to examine household water treatment technologies (HWTS) and evaluate their ability to improve the microbial quality of drinking water. We analyzed 20 paired samples (source and treated) of drinking water from four sources of drinking water in close proximity to homesteads. Samples were analyzed for total coliforms and Escherichia coli, the indicators of faecal contamination, to measure effectiveness of HWTS. The parameters were determined using membrane filtration method. Laboratory data was statistically analyzed using one way ANOVA from SPSS software version 17.0. All HWTS improved the microbial quality of drinking water under laboratory conditions. Mean log10 total coliforms reductions were 2 log10 (99.5%) for boiling, 0.9 log10 (84.8%) for biosand filtration, 1.9 log10 (99.5%) for application of Water Guard tablets and 2 log10 (98.1%) for application of aqua safe tablets. The mean log10 Escherichia coli reductions were 1.2 log10 (100%) for boiling, bio sand filtration, application of Water Guard tablets and application of aqua safe tablets. The microbial removal effectiveness of HWTS was significantly high and the differences in the mean total coliforms reductions by different HWTS were statistically significant (P < 0.05). Water Guard, bio sand filtration, boiling and aqua safe tablets significantly remove total coliforms and Escherichia coli and should therefore is promoted at local level.
Open Access
Effects of Seasonal Variations in Physical Parameters on Quality of Gravity Flow Water in Kyanamira Sub-County, Kabale District, Uganda
(Scientific Research Publishing, 2016) Hannington, Ngabirano; Denis, Byamugisha; Emmanuel, Ntambi
The effect of seasonal variations in physical parameters on quality of gravity flow water was investigated in Kyanamira Sub-County, Kabale District, Uganda. The seasonal variations in the physical parameters (pH, temperature, electrical conductivity (EC), turbidity, colour, total dissolved solids (TDS), and total suspended solids (TSS)) were determined during wet and dry seasons. Composite samples from gravity flow water sources were collected monthly from March to August, 2014 and then analyzed. Temperature was measured using thermometer; pH, EC and TDS were determined using a multimeter, turbidity, colour and total suspended solids were determined by spectrophotometric method. TDS, pH and temperature were the most contributing parameters to water quality variations in both seasons. The mean pH values varied between 3.78 - 4.84 from March to August, 2014 at all study sites. These pH values were consistently below the WHO permissible range of 6.5 - 8.5. Similarly, total suspended solids varied between 0.66 - 2.17 mg∙L−1 and were well above the recommended WHO limit of zero mg∙L−1 at all study sites. Turbidity mean values varied between 0.83 - 3.7 NTU and were outside the recommended limits of 3 NTU at Kigata (3.7 NTU) only. Temperatures (20.3˚C - 21.15˚C) for all the study sites were within the recommended limit of 20˚C - 30˚C in water for domestic purposes. The mean values of physical parameters for the wet season were: temperature (21.12˚C), colour (12.5 PtCoU), turbidity (3.4 NTU), TDS (76.76 mg∙L−1), TSS (2.13 mg∙L−1), pH (4.19) and EC (152.7 μS∙cm−1) were different from those of the dry season (temperature (20.99˚C), colour (0.93 PtCoU), turbidity (0.53 NTU), TDS (77.33 mg∙L−1), TSS (0.67 mg∙L−1), pH (4.86) and EC (158.65 μS∙cm−1). Basing on these findings above, it was evident to justify discouraging the use of gravity flow water at these study sites for domestic purposes without proper treatment.
Open Access
Identification of Soil and Water Conservation Technologies Used on Different Landscape Positions in Maziba Sub-catchment
(Kabale University, 2016) Ndemere, Julius; Mary makokha; Tenywa Moses
Abstract. Soil and water resources are important for sustaining life on earth since they are the main components of sub-catchments. Despite the technologies that have been introduced in Maziba sub-catchment, farmers have variations in technology acceptance due to over cultivation of land, population pressure, and deforestation that accelerate soil erosion. The objective of the study was to characterize soil and water conservation technologies used at different landscape positions by farmers in Maziba sub-catchment. Descriptive statistics were used to analyze soil and water conservation technologies practiced in the study area. Probability sampling technique was used to select research respondents, who were selected to obtain predominantly used soil and water conservation technologies data, using semi-structured questionnaire. Statistical analysis of the data collected was done using special packages for social scientists (SPSS 17.0) statistical software and Microsoft Excel 2007. The study revealed that terracing (35%), mulching (21%) and trenching (13%) were the predominant soil and water conservation technologies reported. The study recommended formal education for non-educated farmers since the level of education influenced the use of soil and water conservation technologies in the study area
Open Access
Animal-Plant Interaction:
(Exclusive Journal Publishing House, 2017) Ndizihiwe, Daniel R.; Achille, E Assogbadjo; Sylvestre, C. A. M. Djagoun; Barthélémy KASSA
The study was based on 107 studies and data concerning disperser species, plant species and family, fruit type and size, seed size plant life form and the habitat, were presented in matrix form. Data from this matrix were used in determining the disperser species diversity considering large taxonomic groups (mammals, birds and reptiles) and selection pattern based on the fruit and seed size. The diversity of mammals was high followed by birds and then reptiles with 65%, 30% and 5% respectively. Mammal taxonomic group dominated and was sub divided into primates, ungulates, carnivores, rodents and bat sub-groups which accounted for 45%, 22%, 17%, 9% and 7% respectively confirming the dominance of primates. Simple correspondence analysis showed that ungulates dispersed very small fruits while carnivores, primates, bats and reptiles were categorized together for both small and medium sized fruits. Ungulates, birds and bats dispersed the smallest seeds while others dispersed both small and large sized seeds. The study revealed high diversity of mammals particularly primates therefore playing a huge role in structuring and restructuring terrestrial ecosystems, with a warning that the loss of ungulates may have catastrophic impacts on the structure and composition of small fruited and seeded plants.
Open Access
Temporal and Spatial Seasonal Variations in Quality of Gravity Flow Water in Kyanamira Sub-County, Kabale District, Uganda
(Scientific Research Publishing, 2017) Hannington, Ngabirano; Denis, Byamugisha; Emmanuel, Ntambi
The study was designed to investigate temporal and spatial seasonal variations in quality properties of gravity flow water samples collected from Kigata, Kacuro, Kihanga, Kitibya and Kanjobe located in Kyanamira Sub-County, Kabale District, Uganda. Physical, chemical and biological parameters such as pH, temperature, dissolved oxygen, total dissolved solids, electrical conductivity, turbidity, colour and total suspended solids, total hardness, total alkalinity, chloride, fluoride, nitrates-N, nitrites-N, ammonium-N, sulphates, total phosphate, sodium, calcium, magnesium and some heavy metals were analyzed. Total iron, lead, chromium, copper, zinc, manganese and cadmium were analyzed by atomic absorption spectrometry. Two of the basic biological parameters for drinking water such as faecal coliforms and salmonella were analyzed by incubation followed by counting colony forming units (CFUs). Statistical presentations of data including cluster analysis, dendrograms and principal component analysis were used with the assistance of PAST software. Temperature, pH, TDS dissolved oxygen, cations, anions (chemical parameters) and salmonella, faecal coliforms were the major contributing parameters to gravity flow water’s quality variations during both seasons. Values of pH ranged between 3.78 and 4.84 from March to August in all study sites and they were consistently below the WHO permissible pH range of 6.5 - 8.5. Total suspended solids ranged between 0.66 and 2.17 mg·L−1 and were above the recommended WHO limit of zero value in all study sites. Salmonella and faecal coliforms colonies were present in scaring numbers in the wet season. In March, salmonella counts at Kacuro (14 CFU) and Kanjobe (128 CFU) while faecal coliforms counts at Kacuro (515 CFU) and Kanjobe (228 CFU). The findings of this study call for special attention when using gravity flow water.
Open Access
Mercury and its Associated Impacts on Environment and Human Health: A Review
(Omega Publishers, 2018) Alex, Saturday
Mercury exists naturally and as a man-made contaminant. The release of processed mercury can lead to a progressive increase in the amount of atmospheric mercury, which enters the atmospheric-soil-water distribution cycles where it can remain in circulation for years. Mercury poisoning is the result of exposure to mercury or its compounds resulting in various toxic effects depending on its chemical form and route of exposure. The major route of human exposure to methylmercury (MeHg) is largely through eating contaminated fish, seafood, and wildlife which have been exposed to mercury through ingestion of contaminated lower organisms. MeHg toxicity is associated with nervous system damage in adults and impaired neurological development in infants and children. Ingested mercury may undergo bioaccumulation leading to progressive increases in body burdens. Mercury has profound neurological, endocrine, reproductive, and fetotoxicity effects. Although most countries recognize the need to combat mercury pollution, controls are either nonexistence or inadequate. Based on articles reviewed, we recommend community education on need for a reduction in use of products that contain mercury. Dentists should reduce or eliminate the use of mercury amalgam and use pre-encapsulated amalgam instead of mixing their own if they are to continue using amalgam. Environment management agencies should expand existing national research on environmental and health effects of mercury.
Open Access
Modeling The Role Of Wild Birds and Environment in the Dynamics of Newcastle Disease in Village Chicken.
(Science Asia, 2018) Furaha, Chuma; Gasper G., Mwanga; Damian, Kajunguri
Newcastle disease is common viral poultry disease which leads to a massive killing of chicken if preventive measures are not well taken. In this paper, we develop and analyze a deterministic model to investigate the role of wild birds and environment on the transmission dynamics of Newcastle disease in village chicken. We compute the basic reproduction number (R0), a threshold that tells the presence of the disease in a population. Finally, we performed the sensitivity analysis of parameters to see their relationship with the basic reproduction number (R0). The numerical results show that the basic reproduction number (R0) is more sensitive to the contact rate between the susceptible village chicken, wild birds and contaminated environment. This implies that, more contamination of the Newcastle virus into the environment increase the chance for the repeatedly occurrence of the disease. The results also shows that increasing the clearance rate of Newcastle disease virus in the environment reduces the rate of spread of the disease in chicken population. Therefore, contaminated environment plays a crucial role in the transmission of Newcastle diseases in the village chicken population.
Open Access
Mass transfer approach and the designing of horizontal subsurface flow constructed wetland systems treating waste stabilisation pond effluent
(IWA Publishing, 2018) Anita M., Rugaika; Damian, Kajunguri; Rob, Van Deun; Bart Van der, Bruggen; Karoli N., Njau
Pilot-scale constructed wetlands (CWs) that allowed wastewater to flow with high interstitial velocities in a controlled environment were used to evaluate the possibility of using mass transfer approach to design horizontal subsurface flow constructed wetlands (HSSF-CWs) treating waste stabilisation ponds (WSPs) effluent. Since CW design considers temperature which is irrelevant in tropics, mass transfer approach could improve the design. HSSF-CWs were operated in batch recycle mode as continuous stirred tank reactors (CSTR) at different interstitial velocities. The overall removal rate constants of chemical oxygen demand (COD) at various interstitial velocities were evaluated in mesocosms that received pretreated domestic wastewater. The mean overall removal rate constants were 0.43, 0.69, 0.74 and 0.73 d 1 corresponding to interstitial velocities of 15.43, 36, 56.57 and 72 md 1, respectively. Results showed that the interstitial velocities up to 36 md 1 represented a range where mass transfer effect was significant and, above it, insignificant to the COD removal process. Since WSPs effluent has high flow rates and low organic load, it is possible to induce high interstitial velocities in a HSSF-CW treating this effluent, without clogging and overflow. The performance of these HSSF for tertiary treatment in tropical areas could be improved by considering flow velocity when designing.
Open Access
Farmers’ Perception of the Impacts of Climate Variability and Change on Food Security in Rubanda District, South Western Uganda
(OMMEGA Publishers, 2018) Willbroad, Byamukama; Bello N.J; Omoniyi T.E
Climate variability adversely impacts crop production and imposes a major constraint on farming planning, mostly under rain fed conditions across developing countries. Considering the recent advances in climate science, many studies are trying to provide a reliable basis for climate, and subsequently agricultural production forecasts. Rainfall and temperature variability from season to season greatly affects soil water availability to crops, and thus poses crop production risks to agriculture which is a major economic activity in Rubanda District, Southwestern Uganda. It was observed that farmers tend to rely on their accumulated experience about weather conditions in the schedule of their farm operations. Therefore this study was designed to examine farmers’ perception of the impacts of climate variability and change on food security in Rubanda District of Southwestern Uganda. Primary data were obtained through questionnaire administration and field observations among the farmers in Rubanda district. Secondary data was obtained from Kabale Meteorological center (rainfall and temperature) between 1976 and 2016. Simple random sampling technique was employed in the selection of sample size and a total of 200 farmers were randomly selected for the study. The selection of the sample size was based on the procedure of Yamane (1967). Microsoft Excel office 2013 was used to show trends of climate variability and change and SPSS version 20 for descriptive analysis. The results of the analyses showed that temperature increased significantly whereas a decreasing trend of rainfall was observed. Farmers perceived the variability of the climate to have led to the decline of agricultural production hence impacting on food security. The chi-square analysis showed that Climate variability and change has significant relationship with food availability (p < 0.05), food access (p < 0.05), food consumption (p < 0.05) and food stability (p < 0.05). The test also showed that there is variation in the perception of climate variability and change among the farmers in Rubanda District (p < 0.05). Climate variability and change factors have the potential for climatic stress on food security according to the observed agricultural production decline and farmers are seasonally faced with problems of food deficits due to unpredicted extreme weather events. The study established that policies, improved access to climate forecasting and dissemination and accessible extension service should be directed toward interventions to improve agriculture productivity by addressing issues concerning aspects of climate variability and change that constantly affect the dimensions of food security.
Open Access
Restoration of Degraded Agricultural Land
(Ommega Publishers, 2018-09-26) Alex, Saturday
Restoration of agricultural land is important for sustainability of agriculture and environment. Land is under immense pressure due to ever increasing population thereby ensuing growing demand for food, fiber and shelter. Agricultural land is being deteriorated due to different anthropogenic and natural factors. The basic factors causing soil erosion- induced degradation are wind and water erosion. Acidification, compaction and salinization are some other causes of agricultural land degradation. The main causes of erosion on agricultural land are intensive cultivation, overgrazing, poor management of arable soils and deforestation. Restoration of eroded agricultural land is achieved through several agronomic and biological techniques. Crop rotations, agro-forestry, reduced tillage, cover crops, vegetative filter strips, residue, and no-till are important among these. Biological measures such as buffers, conditioner application in direct contact with the soil surface, crop residues using manure protect the soil from erosion. Restoration of saline agricultural land can be achieved through recharge stabilization and reconstruction of saline land through fencing, retain remnant vegetation, revegetation, runoff interception earthworks, and water table lowering.
Open Access
Low concentrations of Lactobacillus rhamnosus GG ( Yoba®) are safe in male Drosophila melanogaster
(Research Note, 2019) Keneth Iceland, Kasozi; Aisha, Bukenya; Ejike, Daniel Eze; Josephine, Kasolo; Dickson Stuart, Tayebwa; Fred, Ssempijja; Joy, Suubo; Andrew, Tamale; Isaac, Echoru; Ibrahim, Ntulume; Sarah Kemuma, Onkoba; Lisa Nkatha, Micheni; Emmanuel Tiyo, Ayikobua; Oscar Hilary, Asiimwe; Muhamudu, Kalange
Objective: The purpose of the study was to generate information on the safety of probiotics, thus the study objectives were to evaluate the effects of Yoba ® on basic physiochemical properties. The study assessed male w1118 Drosophila melanogaster which were provided food supplemented with Yoba ® at 1%, 3%, 6%, and 12% on motor function, total protein, catalase activity, and hydrogen peroxide scavenging activity and lifespan. Results: Yoba® at high concentration (≥ 6%) increased locomotor activity in Drosophila melanogaster, however, total protein, catalase, and hydrogen peroxide scavenging activity were significantly higher at 1% Yoba ® compared to 3%, 6%, and 12% Yoba ®. Yoba consumed at 1% was associated with greater physiological benefits in Drosophila melanogaster. Findings in the study offer a rationale for the consumption of Yoba ® at 1% in humans as is currently being promoted by the Yoba for Life consortium, however, high concentrations of Yoba ® would disrupt physiological function as shown by this study.
Open Access
Analysis of Bacteriological Quality of Domestic Water Sources in Kabale Municipality, Western Uganda
(Scientific Research Publishing Inc., 2019) Alex, Saturday; Johnson, Runyonyozi
In the present study, we assessed the bacteriological quality of water of drinking water sources in Kabale Municipality. A total of 28 water samples were collected from 14 water springs during the dry and wet season and analyzed for determination of Escherichia coli (E. coli), and Total Heterotrophic Bacteria (THB) using the membrane filtration method. Most water springs located in less than 20 meters away from residential areas were associated with bacterial contamination. The mean concentrations of E. coli, total coliforms, and THB were 24.07 CFU/100 ml, 85.71 CFU/100 ml, and 197.07 CFU/100 ml, respectively in the wet season. While in the dry season, the mean concentrations were 2 CFU/100 ml, 10 CFU/100 ml, and 91 CFU/100 ml for E. coli , total coliforms, and THB, respectively. There were significant differences between CFU of total coliforms, HTB, between wet and dry seasons (p = 0.026). Samples collected and analyzed during the wet season for total coliforms did not conform to WHO drinking water quality guideline value of no detection per 100 ml. The study concludes that the majority of spring water sources are located in less than 20 meters away from residential areas with significant paved areas, the presence of septic tanks and pit latrines. Wet season significantly affects the quality of domestic water sources than the dry season. The study recommends that spring water should be treated before drinking due to high bacteria concentrations which makes it unsafe for consumption.
Open Access
Improved estimates for extinction probabilities and times to extinction for populations of tsetse (Glossina spp)
(PLOS, 2019) Damian, Kajunguri; Elisha B., Are; John W., Hargrove
A published study used a stochastic branching process to derive equations for the mean and variance of the probability of, and time to, extinction in population of tsetse flies (Glossina spp) as a function of adult and pupal mortality, and the probabilities that a female is inseminated by a fertile male. The original derivation was partially heuristic and provided no proofs for inductive results. We provide these proofs, together with a more compact way of reaching the same results. We also show that, while the published equations hold good for the case where tsetse produce male and female offspring in equal proportion, a different solution is required for the more general case where the probability (β) that an offspring is female lies anywhere in the interval (0, 1). We confirm previous results obtained for the special case whereβ= 0.5 and show that extinction probability is at a minimum for β>0.5 by an amount that increases with increasing adult female mortality. Sensitivity analysis showed that the extinction probability was affected most by changes in adult female mortality, followed by the rate of production of pupae. Because females only produce a single offspring approximately every 10 days, imposing a death rate of greater than about 3.5% per day will ensure the eradication of any tsetse population. These mortality levels can be achieved for some species using insecticide-treated targets or cattle— providing thereby a simple, effective and cost-effective method of controlling and eradicating tsetse, and also human and animal trypanosomiasis. Our results are of further interest in the modern situation where increases in temperature are seeing the real possibility that tsetse will go extinct in some areas, without the need for intervention, but have an increased chance of surviving in other areas where they were previously unsustainable due to low temperatures.
Open Access
Factors Influencing the Uptake and Sustainable Use of Soil and Water Conservation Measures in Bubaare Micro-Catchment, Kabale District, South Western Uganda
(OMMEGA PUBLISHERS, 2019) Willbroad, Byamukama; Ssemakula, E; Kalibwani, R
Soil erosion and declining soil productivity still continue to manifest in most of the agricultural systems found in Sub-Sahara Africa. As a consequence, this has threatened the agricultural productivity, biodiversity, water quality and availability as well as the livelihoods of the poor who depend on land. In Uganda, this has been attributed to poor land use practices with inadequate SWC measures and persistent nutrient mining of the soils with little or no replenishment. Highland areas of Kabale are reported to be severely affected by soil erosion and declining soil fertility despite continued efforts by farmers to conserve soil and water resources. The study examined the Soil and Water Conservation measures in Bubaare micro-catchment. The study was conducted to assess factors (i) physical (ii) institutional and (iii) socio-economic influencing adoption and sustainable use of soil and water conservation measures in Bubaare micro- catchment in Kabale district. The study was cross sectional in nature employing both qualitative and quantitative approaches to capture data from a sample of 397 respondents using semi-structured questionnaires interviews and observation. Data was analyzed using SPSS version 16 to generate both descriptive and inferential statistics that aided in presentation and interpretation. It was found that 22.9% of the farmers in the area were conserving soil and water using mulches and cover crops, 21.9% agroforestry, 16.8% terraces, 11.3% surface drainage ways, 8% contour bunds, 8% grass bunds, 11% trenches/ditches and 3.3% woodlots. Factors that were statistically determined to significantly influence the adoption and sustainable use of soil and water conservation implementation in Bubaare micro-catchment were physical, institutional, and socio-economic factors. In this regard, several key recommendations were made which involved extending financial services to the farmers, communication and information access, training and experience sharing, strengthening research and development, education and awareness, providing technical and financial support.
Open Access
A Survey of Avian Fauna in Kabale Municipality, South Western Uganda
(Advances in Research, 2020) Sarah, Nachuha; Fortunate, Twagiramaria
Collection of data on avifaunal diversity is a crucial component for monitoring the effects of habitat changes on biodiversity. A rapid cross sectional survey to document common bird species present in Kabale municipality was conducted over a period of 3 months. Birds were categorized into families and the Shannon–Weaver (H') diversity index and the abundance of all the species was calculated. A total of 1770 bird individuals consisting of 67 species, 34 families were recorded, with an overall species diversity of 3.41. The Grey Crowned Crane (Balearica regulorum) an endangered species and the Woolly–necked Stork (Ciconia episcopus) a vulnerable species were among the species recorded. The relatively high diversity is probably attributed to the presence of trees on farmland areas within the municipality. This combination seems to provide various food sources or nesting and perching grounds for the birds. Information generated by this study will serve as a benchmark for monitoring of changes in species diversity and composition over time. In addition, the list of birds will be useful to residents of the area and the many ecotourists who visit Kabale town.
Open Access
Mathematical Modelling of Growth Dynamics of Infant Financial Markets
(Scientific Research Publishing Inc, 2020) Ronald, Katende
Developing financial markets are sensitive in many ways. Even some seemingly insignificant factors can impact their growth or failure. In this paper, we examine the major compartments of an infant financial market and the major contributors to the market’s growth using a simple deterministic mathematical model. We find that the impact of single investor on the market is dependent on the rate at which people choose to invest and the rate at which people leave the market due to non investment-related issues.
Open Access
Linear analysis of bump on tail instability with non-Maxwellian distribution function
(IOP Publishing, 2020) Noreen, N; Shiekh, A; Habumugisha, I; Zaheer, S; AShah, H
The growth rate of bump on tail instability propagating in unmagnetized plasma has been derived. The dispersion relation has been characterized for (r, q) distribution function with spectral indices r and q which ultimately contributes towards tails and shoulder of distribution function. The growth rate of the bump on tail instability has been estimated numerically for different ratios of temperature and number density using solar wind data and also by varying values of indices r and q . The higher value of q play the role towards decreasing the growth rate where the instability has the higher value when the number density of the superthermal electrons in the bump is higher and the temperature is low. The maximum growth rate increases with the increase in number density of electrons and decreases with the increasing temperature in the bump.
Open Access
Foraging Behaviour of the Black-Headed Heron at Kibimba Rice Scheme, Eastern Uganda
(Advances in Research, 2020) Sarah, Nachuha; M. Polycarp, Mwima
Variations in the factors affecting prey availability directly impact on the spatial dispersion of foraging birds. The feeding success and efficiency of the Black-headed Heron (Ardea melanocephala) was examined in the different growth stages/phases of paddy rice, namely: Ploughed fields, Phase 1 fields (2 weeks-1 month after sowing) and Harvested fields. Feeding success of the Black-headed Heron varied significantly across the rice growth stage. This variation was explained by a combination of factors such water depth, waterbird abundance, Nearest Neighbor Distance (NND) and food or prey abundance (except amphibian abundance). Statistical analysis were conducted using Genstat Version 8.1 (VSN Intl.2003, in which a General Linear Mixed Model were used to examine the variation in each behavioural measure. Foraging in aggregations on rice paddies seems to be more beneficial to the Black-headed Heron. The closeness to a conspecific had a positive effect on the feeding efficiency of the Black-headed Heron as they foraged on fields with abundant prey (Phase 1) and a negative effect on fields with less abundant prey (Ploughed fields). Generally, the data seem to suggest that there is a functional relationship between the Black-headed Heron, and prey abundance, and the absence of interference competition on rice fields.
Open Access
On the structure of quasi-Keplerian accretion discs surrounding millisecond X-ray pulsars
(Indian Academy of Sciences, 2020) Isaac, Habumugisha; Solomon, B. Tessema; Edward, Jurua; Simon, K. Anguma
In this study, we investigated the time-independent dynamics (disc structure, forces and torques) of a quasi-Keplerian disc around a millisecond pulsar (MSP) with an internal dynamo. We considered the disc around a MSP to be divided into the inner, middle and outer regions. By assuming that the disc matter flows in a quasi-Keplerian motion, we derived analytical equations for a complete structure (temperature, pressure, surface density, optical depth and magnetic field) of a quasi-Keplerian thin accretion disc, and the pressure gradient force (PGF). In our model, the MSP-disc interaction results into magnetic and material torques, such that for a given dynamo ( ) and quasi-Keplerian (n) parameter, we obtained enhanced spin-up and spin-down torques for a chosen star spin period. Results obtained reveal that PGF results into episodic torque reversals that contribute to spinning-up or spinning-down of a neutron star, mainly from the inner region. The possibility of a quasi-Keplerian disc is seen and these results can explain the observed spin variations in MSPs like SAX J1808.4-3658 and XTE J1814-338.