Department of Science, Technology and Engineering

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Aerosol optical depth and precipitation rate projections over east africa utilizing self organizing map
(The International Journal Of Science & Technoledge, 2017-03-01) Makokha, John Wanjala; Angeyo, H.K.; Muthama, John Nzioka
Assessment of future aerosols impacts on both regional and global climate change requires a comprehensive projection tool that reliably provides information on aerosol evolution characteristics with high fidelity. In the current study, we propose an algorithm based on Self-Organizing Map (SOM) and Community Atmosphere Model 4 (CAM4) for long term Aerosol Optical Depth (AOD) and Precipitation Rate (PR) projections over East Africa. To start with, AOD and PR retrievals from Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measurement Mission (TRMM) respectively were cross validated with simulation from CAM4 so as to assess the uncertainty between the measured and simulated retrievals from 2000 to 2014.The error analysis between CAM4 simulations and MODIS measurements (from 2000 to 2014)shows a close match where R2 varies from 0.58 to 0.83 with a corresponding RMSE of between 0.014 and 0.065 (for AOD). Likewise, the uncertainty between simulate and measured PR from CAM4 and TRMM showed an estimated R2 to range between 0.40 and 0.78 while the RMSE varied from 0.021 to 0.091 in the same period and study sites. Based on proposed SOM algorithm and simulated CAM4 retrievals over each study site, an increase of between 1.34-2.43 % for AOD and a decrease of between 1.03-1.98 % in PR are projected over the region by 2030.
Characterization and evaluation of repellent effect of essential oil of mangifera indica l. from Kenya
(Journal of Essential Oil Bearing Plants, 2013-03-12) Alwala, J.O.; Wanzala, W.; Inyambukho, RA.
Ethnopharmacologically, the mango has a lot of applications in life in humanhealth and ethnoveterinary medicines since ancient times. The study aimed at characterizing theessential oil of Mangifera indica L. leaves and evaluating its repellent effect on the host-seekingfemale Anopheles gambiae,the vector of African malaria. The essential oil was obtained byhydrodistillation and analyzed by gas chromatography (GC) and gas chromatography-massspectrometry (GC-MS). The repellent effect of the essential oil was evaluated using the human-baittechnique to simulate field situation. Of the 26 major hydrocarbon compounds identified, α-pineneoccurred in the largest amount (33.3 %), followed by α-phellandrene (22.6 %), Limonene (13.2 %),p-cymene (6.1 %), Heptane (3.8 %), β-pinene (2.6 %), Ledene (1.3 %), (-)-α-gurjunene (1.2 %), β-myrcene (1.1 %), γ-terpinene (1.0 %), (+)-2-carene (0.9 %) and trans (β)-caryophyllene (0.9 %) inthat order. The oil showed a significant dose-dependent repellent effect on host-seeking femaleAnopheles gambiae s.s. The oil showed a complex composition of hydrocarbon compounds andmay be richer in monoterpenes than in any other type of compounds. It showed the potential to repelmosquitoes.
Chemical composition of essential oil oftithonia diversifolia(hemsl.) a. gray from the southern slopes of Mount Elgon in western Kenya
(I J E P P, 2016-06-01) Wanzala, W.; Osundwa, E.M.; Alwala, O.J.; Gakuubi, M.M.
Ethnopharmacologically, Tithonia diversifolia has a lot of applications in the history of human life. The current study aimed at characterizing the essential oil from fresh aerial parts of T. diversifolia. The plant materials were obtained from western Kenya and oil extracted by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Compounds were identified by comparison of their mass spectra with those in Wiley NBS and NIST databases and GC retention times to those of authentic samples. The percentage yield of the essential oil of T. diversifoliawas 0.00015% w/w. The oil showed a complex composition of about 50 compounds, a mixture of monoterpenes and sesquiterpenes, 54% and 46%, respectively.Within the sub-classes of terpenes, hydrogen-carbon-containing terpenes (72%) occurred more than oxygen-containing terpenes (28%) with hydrogen-carbon-containing sesquiterpenes (38%) occurring in the highest proportion, followed by hydrogen-carbon-containing monoterpenes (34%), oxygenated monoterpenes (20%) and oxygenated sesquiterpenes (8%). Twenty-four percent of the 50 compounds and most of the monoterpenes were found in literature to have some repellence properties. Of these 50 compounds, α-pinene occurred in the largest amount (63.64%), followed by β-pinene (15.0%), iso-caryophyllene (7.62%), nerolidol (3.70%), 1-tridecanol (1.75%), limonene (1.52%), sabinene (1.00%), α-copaene (0.95%), α-gurjunene (0.56%) and cyclodecene (0.54%). With multipotential applications nature of T. diversifoliaplant and its products, these compounds may in future be useful in pharmaceutical, agricultural, food and perfumery industries
Contextualized science teaching and student performance: the case of a Kenyan girls science class
(Instituto de Relaciones Internacionales" Daza de Valdes", 2017-06) Ooko, Selline; Beru, Festus K.; Nashon, Samson M.; Anderson, David; Namazzi, Elizabeth
This paper is about a case study that investigated the impact of contextualized science teaching and learning onperformance of a Form three (Grade 11) class in one of Kenya’s girls high schools. The class experienced nine weeks ofcontextualized science learning. This involved a full day visit toJua Kaliwhere they interacted with artisans. ‘‘Jua Kali’’ is asmall-scale manufacturing and technology-based service sector where artisans manufacture equipment and otherhousehold items that are ubiquitous in everyday Kenyan culture. The visit was followed by organized classroom-basedgroup discussions about what they had learnt and considered most relevant and meaningful. Following this highlyengaging student learning discourse, their creativity and innovative abilities in science improved tremendously as reflectedin the quality of class presentations and participation in the National Science Congress. Moreover, the school’sperformance in the Kenya Certificate of Secondary Education (KCSE): a final national exam at the end of Form 4(Grade 12) improved from a mean of 9.3 in the previous year to 10.4 in the intervention year (p = 0.022). This was furtherattributable to significant improvement in all science subjects: biology, chemistry, physics and mathematics. Besides thecritical insights about theJua Kali’srichness in scientific phenomena, there is also great potential for contextualized scienceexperience to enhance students’ deeper understanding of science.
Determination of tannin concentrations in african indigenous vegetables, grains and cassava roots from Emuhaya District, western Kenya
(Sciknow Publications Ltd : American Journal of Nutrition and Food Science, 2014-01-01) Wanzala, W.; Alwala, J.O.; Kiema, Francis N.
The studyevaluated tanninconcentrations in four vegetables, three grains and cassava roots as the most common foodstuffs in the diet of local communities from Emuhaya district in western Kenyaand their nutritional health implication. Plant specimens were collected from local arable farms and market centres and their identities confirmed at Maseno University herbarium. Tannincontent was evaluated using the International Phamacopoeia Method.Percent compositionof tannins in the sampled specimens were: 9.49±0.6 for rattle pod (Crotalaria brevidens(Emiroo); Family, Fabaceae), 8.38±0.3 for narrow-leaf bitter-pea(Daviesialeptophylla(Omurere); Family, Fabaceae), 2.49±0.2 for amaranth (Amaranthushybridus(Tsimboka); Family, Amaranthaceae), 0.42±0.04for black nightshade(Solanumnigrum(Lisutsa); Family, Solanaceae), 9.21±0.4 for peanut/groundnut (Arachishypogaea(Tsinjugu); Family, Fabaceae), 8.24±0.4 for sesame(Sesamumindicum(Tsinuni); Family, Pedaliaceae), 8.11±0.2 for finger millet (Eleusinecoracana(Obulee); Family, Poaceae) and 6.99±0.5 for cassava (Manihotesculenta(Emioko); Family, Euphorbiaceae). Solanumnigrumhad significantly the lowest tannin composition profile followed by A. hybridusand M. esculentain that order (P < 0.05). Interestingly, these three plants are preferred in the diet to the rest of the plants. The results provide scientific rationale for dietary exploitationof these plants bythe local communities and may lay down some groundwork for exploiting partially refined products such as peanut butter and a wide range of grades of flour for human consumption and livestock feeds. However, consumption of tannins in the diet may sometimes benecessary for optimal health but caution needs to be taken for their conflicting adverse medical-based nutritional and physiological effects.
DFT calculations of elastic, electronic and thermal properties of TiB2Mo
(Oxford Open Materials Science, 2022-02-02) Wafula, Job; Manyali, George; Makhokha, John
Ceramics are materials with good mechanical properties; however, low fracture toughness, intrinsic brittleness and poor resistance against oxidation at high temperatures are challenges limiting their applications. TiB2Mo is a ceramic material whose all elastic properties have not been calculated. In this study, we investigated the elastic, electronic and thermal properties of TiB2Mo structure using first principles calculations. All first principles calculations were based on the density functional theory as implemented in Quantum ESPRESSO code with the help of Thermo-pw as a post-processing code. Obtained lattice parameters of TiB2Mo structure were in good agreement with other previous theoretical studies. TiB2Mo structure was found to be mechanically and dynamically stable at ground state conditions. The results also show that TiB2Mo is brittle, anisotropic and metallic in nature. Based on the calculated Vicker’s hardness Hv, we noted that TiB2Mo is classified as a hard material with fracture toughness of above 7MPam0:5; therefore, it is a promising ultra-high temperature ceramic.
EDXRF spectroscopic elemental analysis for efficacy of Kibabii University sewage treatment System
(Open Access Library Journal, 2018-10-18) Situma, Yonah; Odhiambo, Jared Oloo; Makokha, John Wanjala
Elemental analysis of sewage effluents in Kibabii sewage treatment system was achieved via Energy-Dispersive X-Ray Fluorescence (EDXRF) spectroscopy with the aim of assessing the efficacy of the treatment system. Concentrations of lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) were measured based on clay soil “standards” in concentration range for Pb, Hg and As as 12.7 ppm, 14.3 ppm and 8.83 ppm respectively for certification. Among other probable reference materials, clay soil “standards” were used for certification in this work because of similarity in matrix composition with the sediments. The concentration for Hg, Pb, and As in the sewage sediments were 10.65 ± 2.28 ppm, 8.86 ± 2.92 ppm and 3.41 ± 2.18 ppm respectively in lagoon A. In lagoon B the levels were 3.82 ± 0.56 ppm, 6.35 ± 1.50 ppm and 1.67 ± 0.53 ppm respectively. Lagoon C showed a reduction in the levels with 3.74 ± 1.39 ppm for Hg and 2.30 ± 0.27 ppm for Pb. As was not detected in lagoon C, on the other hand, Cd was not detected in all the lagoons. The efficacies in the treatment varied from 30.34% - 51.78%, 37.63% - 65.41% and 76.63% - 84.81% for lagoon A, B and C respectively. The study was successful in quantifying the heavy elements in the lagoons from which the efficacy in the treatment process was determined. The study provided awareness on the elemental concentration levels in the Kibabii University sewage treatment system, hence creating awareness on what is released into River Kibabii. With this information, the surrounding community and the University can partner in order to mitigate the effects of heavy metals in the effluents in future due to the growth of the University day by day.
Effect of CuO2 plane on the thermodynamic properties of double Tl-O layered cuprate based on an interaction between cooper pair and an electron
(2016) Odhiambo, J.O.; Sakwa, T.W.; Rapando, B.W.; Ayodo, Y.K.
Electron interaction near the critical temperature is viewed as a contributor to the establishment of the energy gap which of late is projected to be a harbinger to explaining microscopic mechanism behind High temperature superconductivity. This study investigated the effects of the number of planes of CuO2 on the thermodynamic properties of double Tl-O layered compounds: Tl2Ba2CaxCuyOz (Tl22XY) High temperature superconducting cuprates due to an interaction between a Cooper Pair and an electron. The energy of interaction at the critical temperature (Tc) was seen to increase with increase in the number of CuO2 planes. The specific heat per unit mass, Sommerfeld coefficient as well as the entropy per unit mass, decreased with an increase in the number of CuO2 planes. The peak Sommerfeld coefficient temperature (T’) was noted to be approximately 0.66Tc in all considered cases of Tl22XY.
Effect of duo fermion spin on the specific heat and entropy of a mixture of helium isotopes
(Journal of Multidisciplinary Engineering Science and Technology (, 2018-10-01) Lusamamba, Simon Mwatulo; Sakwa, Thomas W.; Odhiambo, Jared Oloo
Spin normally determines the character, rate of collision and subsequently the properties of ultracold systems. This study investigated the effect of double spin degeneracy on the thermodynamic properties of Helium-3 and Helium-4 isotopes specifically the specific heat and entropy of a grand canonical ensemble. The approach used was statistical in nature where permutation and exclusion was done on fermions and bosons. From thermodynamics, the expression of partition function which was used to derive other expressions of specific heat and entropy as temperature dependence. Specific heat and entropy were found to increase with temperature. The kink in specific heat at a temperature of 35K implied that there was a phase transition.
The effectiveness of coccinellids as natural enemies of aphids in maize, beans and cowpeas intercrop
(2012) Nyukuri, Robert W.; Kirui, Stella C.; Wanjala, Fred M.E.; Odhiambo, J.O.; Cheramgoi, Evelyne
Abstract: A field study was conducted in Busia district of Kenya to elucidate the dynamics of ladybirds in mixed stands of maize, beans and cowpeas to determine their efficacy as sole control measures for Aphids. Maize, beans and cowpeas were intercropped using conventional husbandry practices and the general Coccinellid quantified as follows: Colonies of four Coccinellids, starved for 12 hours to enhance feeding on Aphids were assessed. The effects of weather on the abundance of Coccinellids were also investigated and involved collection of meteorological data from the Busia District Agricultural Office (BDAO) and from Busia Farmers Training Centre (BFTC) and relating them to the abundance and predation values. The predator population was most abundant in the mixed stands of maize and beans (2.33 predators/30 Aphids) as compared to their occurrence in pure stands of cowpeas (0.85 predators/30 Aphids). The genus Cheilomenes spp. was the most ubiquitous predator with a mean of 4.00 individuals/30 Aphids while Hippodamia variegata was the least abundant predator species with a mean of 0.92 individuals/30 Aphids in all the agro-ecosystems. The larvae of Hippodamia variegata were the most bio-efficient, consuming 32.44 Aphids while their adults were the least bio-efficient, consuming 4.22 individuals for a period of 12 hours. The Coccinellids consumed more Aphids at higher aphid densities (24.05 Aphids) than at lower aphid densities (9.44 Aphids) over the same period of time. Rainfall and relative humidity had significant (F = 3.675; P < 0.05) effects on the abundance of Coccinellids. Temperature had significant (F = 3.58; P < 0.05) effect on the abundance of Coccinellids though at a lower level. Rainfall (r = -0.162) and relative humidity (r = - 0.084) were both inversely correlated with the abundance of Coccinellids. On the other hand, temperature was positively correlated (r = 0.159) with the prevalence of Coccinellids indicating that warmer and drier conditions favoured their multiplication. Key words: Efficacy, Coccinellids, Aphids, natural enemies, ecological factors, crops.
Effects of different agroecosystems on prevalence of different species of pests and coccinellid predators
(2012) Nyukuri, Robert W.; Wanjala, Fred M.E.; Cheramgoi, Evelyn; Odhiambo, J.O.; Kirui, Stella C.
Abstract: This study was aimed at determining the effects of mixed and single cropping agroecosystems on the prevalence of different species of insect pests and coccinellids. It involved six growing crops: maize Zea mays L., beans Phaseolus vulgaris L. and cowpeas Vignaunguiculata L. Walp in single and mixed stands and sampling throughout the phenology of the crops. Eight insect pest species were recorded on maize grown alone, while thirty seven insect species were endemic on cowpea mono cropped and were of six orders whereas twenty two insect pest species occurred on beans. The predator population was most abundant in the mixed stands of maize and beans (2.33 predators per 30 aphids) as compared to their occurrence in pure stands of cowpeas (0.85 predators per 30 aphids) as there were numerous aphids on beans at pre-flowering phase that supported a higher population level of coccinellids. Also, predator population was at the peak during the tussling stage of maize as they fed on the pollen grains while aphids on cowpeas co-existed mutualistically with black ants that protected them against predation. The genus Cheilomenes spp. was the most ubiquitous predator with a mean of 4.00 individuals per 30 aphids while Hippodamiavariegata was the least abundant predator species with a mean of 0.92 individuals per 30 aphids in all the agroecosystems as the Cheilomenes spp. had a faster discovery rate, range of perception, effective capture efficiency and a shorter handling time of a prey. Key words: Phenology, stands, Zea mays L., Phaseolus vulgaris L., Vignaunguiculata L. Walp, agroecosystem.
Effects of static electromagnetic fields at 24 hours incubation on the germination of rose coco beans (phaseolus vulgaris)
(2009-05) Odhiambo, J.O.; Ndiritu, F.G.; Wagara, I.N.
This study evaluates the percent germination of Rose coco beans (Phaseolus vulgaris L.) seeds, when exposed to static electromagnetic fields under laboratory conditions incubated for 24 h. This can be replicated in the field to aid short period production of beans, hence higher yield. For a given set of sample, germinating bean seeds were exposed to field generated by Helmholtz coil, North Pole or the South Pole with constant magnetic fields of 5 mT, 10 mT, 30 mT and 60 mT. The exposure period was fixed at 3, 4.5 and 6 h and exposed after 12 h incubation. The germinating seeds were counted after 24 h. Certain trends could be observed; statistical analysis has shown that there is statistical influence (p < 0.05, ANOVA test) of the magnetic treatment on germination of rose coco beans. Maximum seed germination occurred when exposed to South Pole field inducing percent germination of approximately 73% compared to 52% of the control at field strength of 30 mT at exposure period of 4.5 h. The research achieved its aim of proving the influence of static electromagnetic field to germination of seeds in addition to, challenging seed companies to come up with magnetized seeds that will germinate faster.
Estimation of radiative forcing due to aerosols over selected sites in Kenya
(Kenya Meteorological Society : Journal of Meteorology and Related Sciences, 2013-01-01) Makokha, John Wanjala; Angeyo, H.K.
Variations in the radiative characteristics of aerosols can be used to quantify their effects on climate. This study evaluated the temporal-spatial variability of aerosol radiative characteristics at λ = 440 nm, λ = 675 nm, λ = 870 nm and λ = 1020 nm over the Nairobi-1°S, 36°E, Mbita-0°S, 34°E and Malindi-2°S, 40°E sites of Kenya. Aerosol optical properties from AERONET were used as inputs in the Coupled Ocean Atmosphere Radiative Transfer (COART) code to model aerosol radiative effects. The results over Nairobi showed an increase in reflectance of 2.6%, 6.7%, 7.2% and 2.4% for 2006–2007 at the specified wavelengths, respectively. Drops of 2.7%, 12.2%, 50.6% and 25.6% were noted in the same wavelengths for the 2007–2008 period. The reflectance over Mbita (0.2284) was higher than that over Nairobi (0.1396) at λ = 675 nm for 2007, due to biomass burning at site. Maritime conditions and aerosols coupled with long range transport of monsoon winds explain the higher reflectance observed over Malindi when compared to Nairobi, except for λ = 440 nm in 2008. This is as a result of aerosols from vehicular and industrial emissions that dominate the λ = 440 nm over Nairobi. The variability of downward and upward spectral irradiance measured at the surface and 12 km levels depended on the wavelength of measurement, but was temporally invariant. Upward irradiance decreased with increasing Solar Zenith Angles (SZAs) due to strong Fresnel reflection at large angles. The equality in the upwelling irradiances at the two atmospheric levels at all sites for λ = 870 nm and λ = 1020 nm was due to the near IR absorption by aerosols. The radiant flux lost in the spectral range 440–1020 nm remained relatively constant over the study sites, and thus the influence of aerosols on radiative characteristics was independent of both site and period of study.
The influence of AC electromagnetic fields on the initial radicle growth rate of phaseolus vulgaris L.
(FACT Limited, 2009-10-07) Odhiambo, J.W.; Ndiritu, Francis G.; Wagara, Isabel N.
Objectives: To determine if AC electromagnetic fields can be used to improve growth of food crops. This would reduce and minimize contamination of yield that is associated with application of fertilizers to promote plant growth and chemicals to control pests and diseases. Methodology and results: Alternating 50Hz electromagnetic fields generated by Helmholtz coil of 0, 5, 10, 30 and 60mT were applied to germinated Rosecoco bean (Phaseolus vulgaris L.) seedlings. For a given sample, seedlings were exposed to AC electromagnetic field for 3, 4.5 and 6h per day. The radical length of beans was measured after every 12h over a 4 days incubation period. Linear regression analysis showed that the incubation period significantly influenced bean radicle elongation with mean optimum rate of 0.088cm/hr after incubation for 66h. Exposure period and strength of electromagnetic field did not significantly influence the initial rate of radicle elongation of Rosecoco beans. Conclusion and application of findings: Beans growing naturally have a more uniform increase in length than those exposed to AC electromagnetic fields. The growth regulators (hormones) are accelerated after exposure to magnetic field hence higher elongation of radicle. Further research on this need to be done especially if the pretreatment of seeds will give the same results so that it can be used in developing better quality and fast growing bean seed.
Internal energy of a grand canonical ensemble of a mixture of helium isotopes with duo-fermion spin degeneracy
(Centre for Info Biotechnology-IJPMS, 2015-12-01) Lusamamba, Simon Mwatulo; Sakwa, Thomas W.; Odhiambo, Jared Oloo; Oketch, Vincent O.; Ochola, Alphayo
We have considered a system consisting of a mixture of helium isotopes 3He-4He interacting weakly in pairs. The partition function of the system with duo-spin and varying number of bosons and fermions is developed to bring out the superfluid properties of the system. The study focused on a Grand Canonical ensemble of 3He - 4He isotopes whose superfluid properties have been determined by distinctively singling out the duo spin component. The internal energy was established algebraically, analyzed and found out to be increasing with temperature. For high temperatures, internal energy remains constant due to particle saturation.
Investigation of radiative characteristics of the Kenyan atmosphere due to aerosols using sun spectrophotometry measurements and the COART model
(Taiwan Association for Aerosol Research : Aerosol and Air Quality, 2013-01-01) Makokha, John Wanjala; Angeyo, H.K.
Variations in the radiative characteristics of aerosols can be used to quantify their effects on climate. This study evaluated the temporal-spatial variability of aerosol radiative characteristics at λ = 440 nm, λ = 675 nm, λ = 870 nm and λ = 1020 nm over the Nairobi-1°S, 36°E, Mbita-0°S, 34°E and Malindi-2°S, 40°E sites of Kenya. Aerosol optical properties from AERONET were used as inputs in the Coupled Ocean Atmosphere Radiative Transfer (COART) code to model aerosol radiative effects. The results over Nairobi showed an increase in reflectance of 2.6%, 6.7%, 7.2% and 2.4% for 2006–2007 at the specified wavelengths, respectively. Drops of 2.7%, 12.2%, 50.6% and 25.6% were noted in the same wavelengths for the 2007–2008 period. The reflectance over Mbita (0.2284) was higher than that over Nairobi (0.1396) at λ = 675 nm for 2007, due to biomass burning at site. Maritime conditions and aerosols coupled with long range transport of monsoon winds explain the higher reflectance observed over Malindi when compared to Nairobi, except for λ = 440 nm in 2008. This is as a result of aerosols from vehicular and industrial emissions that dominate the λ = 440 nm over Nairobi. The variability of downward and upward spectral irradiance measured at the surface and 12 km levels depended on the wavelength of measurement, but was temporally invariant. Upward irradiance decreased with increasing Solar Zenith Angles (SZAs) due to strong Fresnel reflection at large angles. The equality in the upwelling irradiances at the two atmospheric levels at all sites for λ = 870 nm and λ = 1020 nm was due to the near IR absorption by aerosols. The radiant flux lost in the spectral range 440–1020 nm remained relatively constant over the study sites, and thus the influence of aerosols on radiative characteristics was independent of both site and period of study.
Long term assessment of aerosol radiative forcing over selected sites of East Africa
(scientific Research Publishing, 2018-03-08) Makokha, John Wanjala; Odhiambo, Jared Oloo; shem, Godfrey Juma
Atmospheric aerosols have contributed to radiative forcing through direct and indirect mechanisms. Aerosol effects are important in computing radiative forcing estimates for the past, current and future climate. In this study, a comprehensive assessment of regional aerosol radiative forcing, Optical Properties of Aerosol and Clouds (OPAC) model (wavelength range of 0.25 - 4.0 μm) over selected sites in East Africa was done. Aerosol optical properties constituted the inputs of a Radiative Transfer Model (RTM). Optical properties investigated included Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Asymmetry Parameter (AP). Aerosol Radiative Forcing (ARF) during the study period at the surface (SFC), top of the atmosphere (TOA) and the atmosphere (ATM) was estimated to be –18.4 ± 1.4 W∙m−2, +1.1 ± 0.3 W∙m−2 and +19.5 ± 2.5 W∙m−2, respectively. This corresponds to an increment in net atmospheric forcing at a heating rate of about 0.55 ± 0.05 K/day (0.41 ± 0.03 to 0.78 ± 0.03 K/day) in the lower troposphere. The study points out the significant role played by atmospheric aerosols in climate modification over the area of study. It is recommended that a further assessment be done in view of uncertainties that may impact on the findings and which were not within the scope of this research.
Nutrient reduction in runoff water from sugarcane farms by sedimentation method
(Environmentalist Journal, 2012-09-02) Omwoma, Solomon; Omwoyo, N.W.; Alwala, J.O.; Ongeri, David; Lagat, Sylas; Lalah, Joseph
Due to intensive use of agronomic inputs in sugarcane farming, runoff water from these farms is loaded with high concentrations of nutrients. These nutrients find their way into rivers, lakes and sinks, eutrophicating them. Reducing the levels of these nutrients in runoff water from sugarcane farms before it is discharged into sinks will help solve the problems that arise out of eutrophication. This study employed a simple sedimentation method of making depressions in canals draining runoff water from sugarcane farms and emptying them fortnightly during the rainy season and monthly during the dry season. The method was found to significantly (p ≤ 0.05) reduce water conductivity (μS/cm), turbidity (Nephelometric Turbidity Units), total phosphates, nitrate–nitrogen, potassium, calcium, magnesium, iron, copper, sodium and zinc (ppm) in the dry season from 52.89, 148.70,0.87, 3.34, 446.00, 420.00, 205.00, 12,941.00, 261.00, 398.00, and 484.00 in untreated canals to 48.33, 30.22, 0.21, 2.95, 120.00, 154.00, 98.00, 456.00, 181.00, 234.00, and 311.00 in treated canals, respectively. And in the wet season, the parameters were reduced from 261.46, 719.30, 820.00, 25.16, 654.00, 549.00, 493.00, 19,230.00, 763.00, 748.00, and 903.00 to 128.67, 365.70, 3.47, 10.12, 136.00, 187.00, 167.00, 654.00, 207.00, 321.00, and 231.00, respectively. Dissolved oxygen significantly (p ≤ 0.05) increased from 5.11 to 8.14 ppm in the dry season and from 3.82 to 7.92 ppm wet season. Acidity reduced in the wet season from pH 5.02 to 6.20. It is, therefore, recommended
Optical characterization of atmospheric aerosols via airborne spectral imaging and self-organizing map for climate change diagnostics
(2018-08-03) Makokha, John W.; Odhiambo, J.O.
Self-Organizing Map (SOM) analysis is used to perform optical characterization of both Aerosol Optical Depth (AOD) and Ångström Exponent (ÅE) retrieved from Moderate-resolution Imaging Spectroradiometer (MODIS) in relation to Precipitation Rate (PR) from Tropical Rainfall Measurement Mission (TRMM) over selected East African sites from 2000 to 2014 and further diagnose climate change over the region if any. SOM reveals a marked spatial variability in AOD and ÅE that is associated to changing aerosol transport, urban heat islands, diffusion, direct emission, hygroscopic growth and their scavenging from the atmosphere specific to each site. Temporally, all sites except Mbita and Kampala indicate two clusters in AOD that are associated to prevailing dry and wet seasons over East Africa. Moreover, all sites except Mbita and Mount Kilimanjaro show two clusters in ÅE that are related to aerosol mode of generation and composition over the region. The single cluster in AOD and ÅE over Mbita indicate that aerosol characteristics over the site are influenced by biomass burning and local air circulation rather than the monsoon precipitation throughout the study period.
Predicting daily streamflow in ungauged rural catchments: the case of Masinga catchment, Kenya
(Taylor&Francis, 2007) Mutua, Benedict Mwavu; Klik, Andreas
Access to daily streamflow data at the catchment scale, is a central component of many aspects of water resources and water quality management. However, the majority of river reaches in many catchments in Kenya are ungauged or poorly gauged, and in some cases existing measurement networks are declining. Long-term continuous monitoring is not being done due to high costs of equipment maintenance. Therefore, there is a need for an alternative tool such as a catchment-scale hydrological model that is capable of predicting the daily streamflow. An approach is presented of predicting daily streamflow using a physically-based catchment-scale model, the geospatial Stream Flow Model (SFM). The SFM was developed using the “C” programming language and the user interface was developed using the Avenue script of the ArcView software. The SFM simulates the dynamics of runoff processes by utilizing remotely sensed and widely available global or local data sets. The model was applied in the Masinga catchment, Kenya, and the results gave a model performance coefficient of 0.74 based on the Nash-Sutcliffe statistical criterion.

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