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A comparison of three methods of soil water content determination
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: K.M. Little --- , Republic of South Africa B. Metelerkamp --- , New Zealand C.W. Smith --- , Republic of South AfricaIn forestry the need to manage plantations on a sustainable site-specific basis requires the understanding and management of any growth limiting factors. Soil water regime is a factor considered to be of prime importance with respect to explaining differences in... -
The delta yield procedure for nitrogen fertilisation of maize in South Africa
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: A.A. Nel --- , Republic of South Africa A.A. Bloem --- Department of Agriculture, Republic of South AfricaThe nitrogen fertilisation requirement for maize in South Africa is generaly estimated through the optimum yield-nitrogen rate procedure. The efficacy of this procedure is questionable. Delta yield, the difference between the maize grain yield at the economic optimum and that... -
Fish response to the annual flooding regime in the Kavango River along the Angola/Namibian border
Item type: Journal Article • Journal: South African Journal of Marine Science • Authors: C. H. Hocutt P. N. JohnsonThe results of the first seasonal survey of the fish of the Kavango River flood-plain along the Angola/Namibia border are reported. The river experiences peak flooding from February through June, with the 375-km long floodplain extending up to 5 km... -
COASTAL AQUATIC ECOSYSTEMS, CONSERVATION AND MANAGEMENT STRATEGIES IN NIGERIA
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: E.A. Ajao --- , NigeriaThe coastal ecosystems in Nigeria are classified into four broad regions according to differences in general morphology, vegetation and beach type. They are the barrier lagoon complex, the transgressive mud beach, the Niger delta and the strand coast. The delta... -
RELATIVELY NEGATIVE δ13C RATIOS OF MESOZOOPLANKTON IN THE SUNDAYS RIVER ESTUARY, COMMENTS ON POTENTIAL CARBON SOURCES
Item type: Journal Article • Journal: Southern African Journal of Aquatic Sciences • Authors: H.L. Jerling --- Department of Zoology, South Africa T.H. Wooldridge --- Department of Zoology, South AfricaMesozooplankton, submergent and fringing macrophytes and particles suspended in the water column in the Sundays River estuary South Africa were analyzed for δ13C isotope ratios. Highly negative values (−28.3‰ to −32.0‰) for the mesozooplankton species suggest the possibility of phytoplankton... -
The effect of supplements of crop residues based diets on the performance of steers grazed on natural pasture during the dry season
Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: EM AregheoreTwenty-four White Fulani steers, 20-26 months old, mean initial live weight of 270.6 ± 0.5kg, were divided into three treatment groups to investigate the effects of crop residues supplementation on performance when grazed on natural pasture during the dry season... -
The influence of Pechuel-Loeschea leubnitziae (wild sage) on grass sward and soil seed bank composition
Item type: Journal Article • Journal: African Journal of Range & Forage Science • Authors: MJ Tedder --- Grassland Science, School of Life Sciences, South Africa KP Kirkman --- Grassland Science, School of Life Sciences, South Africa CD Morris --- Agricultural Research Council, c/o School of Life Sciences, South Africa WSW Trollope --- Research and Development, South Africa MC Bonyongo --- Okavango Research Institute, BotswanaSoil seed banks provide not only a historical record of vegetation composition but also the potential for post-disturbance revegetation. Pechuel-Loeschea leubnitziae (wild sage) is a multistemmed, aromatic shrub, occurring in Namibia, Botswana, Swaziland, Zimbabwe and the northern regions of South... -
On Non-reflexive Subspaces of Orlicz Spaces
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Diómedes Bárcenas; Ventura EchandíaSeveral geometric properties of Orlicz spaces are given. Among other things we prove that an N − function Φ satisfies the Δ 2 condition if and only if every non-reflexive subspace of L Φ (μ) contains a complemented copy of... -
Some banach space properties of E φ [0, 1]
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Diomedes BárcenasWe prove several Banach spaces properties of E φ [0, 1], many of them concerning to the Δ2 condition and the presence of c 0 and l 1 in those Banach spaces. -
Rotundity in transitive and separable Banach spaces
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Aizpuru F.J. García-PachecoIn every separable Banach space the set of smooth points of the unit ball is a Gδ dense subset of the unit sphere. In this paper, we find some conditions in order to obtain a similar result for rotund points... -
Almost Perfectly Continuous Functions
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: D. Singh --- Department of Mathematics, IndiaThe aim of the present paper is to continue the study of almost perfectly continuous (≡ regular set connected) functions initiated by Dontchev, Ganster and Reilly. It turns out that in general the notion of almost perfectly continuity is independent... -
Vector integration
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: E.G.F. Thomas --- Johann Bernoulli Institute for Mathematics and Computer Science, The NetherlandsThis paper deals with the theory of integration of scalar functions with respect to a measure with values in a, not necessarily locally convex, topological vector space. It focuses on the extension of such integrals from bounded measurable functions to... -
Potential environmental impacts associated with the proposed abstraction of water from the Okavango River in Namibia
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: P AshtonThe Namibian Department of Water Affairs has in the past faced considerable pressure to relieve the water shortages caused by recent droughts. One of the options considered in 1996, following poor runoff during the 1994/95 and 1995/96 seasons, was a... -
The impact of dredging on macrobenthic invertebrates in a tributary of the Warri River, Niger delta
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: EI Ohimain TOT Imoobe MO Benka-CokerThe macrobenthic invertebrates of a canal, created from a tributary of the Warri River in the mangrove swamp of the Niger Delta, Nigeria, were studied before and after dredging. In the canal dredging resulted in at least a 93% decrease... -
Impact of deltamethrin aerial sprays on adult Cyrtobagous salviniae in Botswana
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: CN Kurugundla --- , Botswana MC Bonyongo --- Harry Oppenheimer Okavango Research Centre, Botswana O Serumola --- , BotswanaThe risk and effect of the insecticide deltamethrin, applied aerially in Botswana to control and eradicate tsetse fly, was studied on the non-target weevil Cyrtobagous salviniae, a biocontrol agent of the aquatic weed Salvinia molesta. Environmentally-simulated short-term toxicity bioassay used... -
Surficial sediments of the wave-dominated Orange River Delta and the adjacent continental margin off south-western Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: J Rogers AJ RauThe textural and compositional characteristics of the surficial shelf sediments north and south of the Orange River Delta are reviewed and compared. Sediments are fractionated and dispersed both north- and southwards of the Orange River mouth by wave action, longshore... -
Competitive Positioning and the Survival of Indigenous Firms in Nigeria: The Case Study of Glomobile, Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Ayodele I. Shittu --- Dongwu Business School and Center for Enterprise Innovation and Development, PR China Jielin Dong --- Dongwu Business School and Center for Enterprise Innovation and Development, PR China Li Jing --- Dongwu Business School and Center for Enterprise Innovation and Development, PR ChinaIn this paper, we provide an exploratory view of the competitive analysis of indigenous firms in Nigeria's dynamic and competitive telecommunications industry. Adopting a case study approach, we analysed the key factors behind the survival of new entrant indigenous firms... -
Evaluation of flooding tolerance in cuttings of Populus clones used for forestation at the Paraná River Delta, Argentina
Item type: Journal Article • Journal: Southern Forests: a Journal of Forest Science • Authors: VMC Luquez --- , Argentina FG Achinelli --- , Argentina S Cortizo --- , ArgentinaWe analysed the responses to flooding of 14 poplar clones used for forestation at the Paraná River Delta, Argentina. Some are commercial clones planted in the area, and others belong to a poplar breeding program from the National Institute of... -
Nature and pattern of lagoon fisheries resource utilisation and their implications for waterbird management in coastal Ghana
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: F Gbogbo W Oduro SK OppongSeasonal patterns in human fisheries resource utilisation and the capture characteristics of fish, swimming crabs and land crabs harvested from four coastal lagoons in Ghana between September 2005 and August 2007 are described. These are discussed in relation to sustainable... -
Low allozyme variation in tigerfish Hydrocynus vittatus (Teleostei: Alestidae) from the Okavango panhandle, with notes on the selection of candidates for artificial breeding
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: M Soekoe --- Centre for Aquatic Research, Department of Zoology, South Africa NJ Smit --- Centre for Aquatic Research, Department of Zoology, South Africa H van der Bank --- Centre for Aquatic Research, Department of Zoology, South AfricaTo ensure the utilisation of optimal tigerfish gene pools for artificial propagation, the hypothesis that tigerfish from the Okavango system should have greater heterozygosity than those from smaller river systems was tested. This electrophoretic analysis provides the first report of... -
On Weaker Forms of Separability
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Maddalena Bonanzinga Filippo Cammaroto Mikhail Matveev Bruno PanseraTwo properties each of which is equivalent to separability for regular spaces and is weaker than separability in general are considered as well as the corresponding cardinal functions. -
Water quality dynamics in the Boro-Thamalakane-Boteti river system, northern Botswana
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: G Tubatsi --- Okavango Research Institute, Botswana MC Bonyongo --- Okavango Research Institute, Botswana M Gondwe --- Okavango Research Institute, BotswanaThe quality of water in aquatic systems is subject to temporal and spatial variations due to varying effects of natural and anthropogenic factors. This study assessed the dynamics of water quality in the Boro-Thamalakane-Boteti river system along an upstream–downstream gradient... -
Toxicity evaluation of effluent from the de-oiling works of a decommissioned Nigerian crude oil pipeline using Palaemonetes africanus
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: NH Amaeze --- Ecotoxicology Laboratory, Department of Zoology, Nigeria FA Adetoro --- Ecotoxicology Laboratory, Department of Zoology, Nigeria OA Adegboro --- Ecotoxicology Laboratory, Department of Zoology, NigeriaOil industry activities often involve the cleaning and replacement of pipelines, usually resulting in the discharge of effluents into waterbodies. The toxicity of de-oiling effluent from a decommissioned crude oil pipeline in the Niger Delta region of Nigeria was assessed... -
Diversity, dispersal and disturbance: cladoceran species composition in the Okavango Delta
Item type: Journal Article • Journal: African Zoology • Authors: Markus Lindholm --- Norwegian Institute for Water Research/NIVA, Norway Dag O. Hessen --- Department of Biology, Norway Lars Ramberg --- Harry Oppenheimer Okavango Research Centre, University of Botswana, BotswanaCommunities exposed to intermediate disturbances have been shown to be more diverse than more stable or unstable systems. We recorded the diversity pattern of zooplankton in the Okavango Delta, Botswana, a system which include water bodies with different stability with... -
Flocking dynamics and roosting behaviour of Meyer’s parrot (Poicephalus meyeri) in the Okavango Delta, Botswana
Item type: Journal Article • Journal: African Zoology • Authors: Rutledge S. Boyes --- University of KwaZulu-Natal, South Africa Michael R. Perrin --- University of KwaZulu-Natal, South AfricaFor most of the year, Meyer’s parrots in the Okavango Delta do not form large feeding flocks, and groups larger than two or three are probably the result of opportunistic aggregation at favoured food items after dispersion from communal roosts... -
Small farmers’ adoption behaviour: Uptake of elephant crop-raiding deterrent innovations in the Okavango Delta, Botswana
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Sekondeko R. Noga --- Okavango Research Institute, Botswana Oluwatoyin D. Kolawole --- Okavango Research Institute, Botswana Olekae Thakadu --- Okavango Research Institute, Botswana Gaseitsiwe Masunga --- Okavango Research Institute, BotswanaThis paper invokes the adoption-diffusion model to examine two introduced elephant crop-raiding deterrent innovations (ECDIs), and the factors influencing their adoption by small farmers in the Okavango Delta, Botswana. Two communities (Gudigwa and Eretsha) were purposefully selected as case studies... -
Recent shoreline changes in the Volta River delta, West Africa: the roles of natural processes and human impacts
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: EJ Anthony --- Aix-Marseille University, France R Almar --- LEGOS (CNRS-IRD-CNES-University of Toulouse), France T Aagaard --- University of Copenhagen, DenmarkThe Volta River delta developed as an asymmetric lobe in a tectonic offset on the coast of Ghana. The delta comprises a large curvilinear spit that widens in its central portion due to the adjunction of successive sandy beach ridges... -
Greenhouse gas inventory: A case of gas flaring operations in Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Solomon O. Giwa --- Department of Agricultural and Mechanical Engineering, Nigeria Abayomi T. Layeni --- Department of Agricultural and Mechanical Engineering, Nigeria Collins N. Nwaokocha --- Department of Agricultural and Mechanical Engineering, Nigeria Musedik A. Sulaiman --- Department of Agricultural and Mechanical Engineering, NigeriaInventories of the greenhouse gases (GHGs) emitted into the atmosphere through gas flaring are scarce; hence, the need for this study. Formulae reported by the Association of Petroleum Institute were used for estimating GHGs based on data (1965 to 2013)... -
The scale effect of economic development and freshwater quality in Nigeria: Environmental pollution of the Lower River Niger Basin
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Chigozie Damian Ezeonyejiaku --- Department of Zoology, Nigeria Maximilian Obinna Obiakor --- School of Environmental and Rural Science, Australia Dymphna Javier --- School of Environmental and Rural Science, Australia Ikem Innocent Ifedigbo --- Department of Zoology, Nigeria Hamilton Chukwuebuka Obiakor --- Department of Public Administration, NigeriaRiver Niger is the third-longest river in Africa and the longest river in West Africa. The river basin traverses West and Central African countries, and forms a coastal delta (in southern Nigeria) where it empties into the Atlantic Ocean. The... -
Spatial and diurnal distribution of carbon monoxide (CO) and its health and environmental implications in selected locations in the Niger Delta Area of Nigeria
Item type: Journal Article • Journal: African Journal of Science, Technology, Innovation and Development • Authors: Iwekumo Ebibofe Agbozu --- Federal University of Petroleum Resources Effurun, Nigeria Osayomwanbor Ebenezer Oghama --- Federal University of Petroleum Resources Effurun, NigeriaEmission of carbon monoxide (CO) poses unprecedented risks in urban environments. Moreover, there has been a growing concern about the incidences of deaths arising from suffocation by CO fumes in Nigeria. Hence, this study attempts to evaluate the spatial and... -
A comparison of the water quality and plankton diversity of the Okamini Stream to the freshwater systems within the New Calabar River catchment, Port Harcourt, Nigeria
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: BB Otene --- Rivers State University, Nigeria I Thornhill --- University of Manchester, United Kingdom J Amadi --- Rivers State University, NigeriaThe water quality and phytoplankton diversity of the Okamini Stream, Port Harcourt, Nigeria was studied between April and June 2018 at three stations. The data was used to assess the health of the system for supporting local communities. Compared to... -
More on cardinality bounds involving the weak Lindelöf degree
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: A. Bella --- University of Catania, Italy N. Carlson --- California Lutheran University, USA I. Gotchev --- Central Connecticut State University, USAWe give several new bounds for the cardinality of a Hausdorff topological space X involving the weak Lindelöf degree ωL(X). In particular, we show that if X is extremally disconnected, then |X| ≤ 2 ωL (X)πχ(X)ψ(X), and if X... -
Stability of Riemann solutions to a class of non-strictly hyperbolic systems of conservation laws
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Shiwei Li --- Henan University of Engineering, P.R. ChinaThis paper is concerned with Riemann problem for a class of non-strictly hyperbolic systems of conservation laws. The two kinds of Riemann solutions including vacuum and delta shock wave are constructed. Under the generalized Rankine-Hugoniot relation and entropy condition, we... -
Comparison of the acute toxicity and behavioural effects of two pyrethroids on African catfish Clarias gariepinus fingerlings
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: EO Ogueji --- Alex Ekwueme Federal University, Nigeria JJ Ekpenyong --- Alex Ekwueme Federal University, Nigeria GU Amana --- Kogi State University, Nigeria EB Tabi --- Alex Ekwueme Federal University, Nigeria IB Okey --- Cross River University of Technology, Nigeria MO Olaolu --- Alex Ekwueme Federal University, Nigeria JN Nwakpa --- Ebonyi State University, NigeriaTwo of the most-commonly used pyrethroid insecticides were subjected to static bioassays to determine their acute toxicity to Clarias gariepinus fingerlings, followed by comparisons of their impact on mortality and behavioural changes in the fish. The LC50 values for deltamethrin... -
Greenhouse gas concentrations in tropical wetlands of the Cross River estuary, Nigeria
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: AB Andem --- University of Calabar, Nigeria OB Ojo --- University of Calabar, Nigeria RA Odey --- University of Calabar, Nigeria GE Eni --- University of Calabar, Nigeria OR Ibor --- University of Calabar, Nigeria IA Iwara --- University of Calabar, Nigeria VO Eyo --- Nigerian Maritime University, NigeriaThe Cross River estuary is a coastal wetland in the south-eastern part of the Niger Delta region of Nigeria with its hydrological cycle largely dependent on precipitation. The purpose of this study was to determine the greenhouse gas (GHG) concentrations... -
Concentration and cavitation in the Riemann solution for the relativistic Euler equations with non-ideal isothermal dusty gas
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Bencui Shan --- Yunnan Normal University, P.R. China Yanyan Zhang --- Xinyang Normal University, P.R. China Yu Zhang --- Yunnan Normal University, P.R. ChinaThe phenomena of concentration and cavitation in the Riemann solutions of the relativistic Euler equations with non-ideal isothermal dusty gas are considered. The Riemann problem is solved first, and the solutions consisting of rarefaction waves and shock waves are obtained... -
Geometry of δ-almost gradient Yamabe solitons on pseudo-Riemannian manifolds
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Rajdip Biswas --- Jadavpur University, India Santu Dey --- Bidhan Chandra College, India Arindam Bhattacharyya --- Jadavpur University, IndiaIn this article, we studied δ-almost Yamabe solitons within the framework of paracontact metric manifolds. First, we proved that for a paracontact metric manifold M , if a paracontact metric g represents a δ-almost Yamabe soliton associated with the potential... -
Delta-shocks and vacuums as flux-approximation limit of solutions to the Aw-Rascle model with time-dependent source
Item type: Journal Article • Journal: Quaestiones Mathematicae • Authors: Mengqi Cui --- Department of Mathematics, Yunnan Normal University, P.R. China Shuai Fan --- Department of Mathematics, Yunnan Normal University, P.R. China Yu Zhang --- Department of Mathematics, Yunnan Normal University, P.R. ChinaThe flux-approximation limit of solutions to the Aw-Rascle (AR) traffic flow model with time-dependent source is considered. First, the Riemann problem containing flux perturbation and generalized Chaplygin gas (GCG) pressure is solved. Then, it is proved that, as the flux...