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Abstract A general and systematic procedure is developed for calculating the hydrodynamic force and torque experienced by an arbitrarily-sized, -shaped and -oriented particle undergoing an arbitrarily-directed translational and rotational... more
Abstract A general and systematic procedure is developed for calculating the hydrodynamic force and torque experienced by an arbitrarily-sized, -shaped and -oriented particle undergoing an arbitrarily-directed translational and rotational motion inside one of two semi-infinite immiscible fluids separated by a planar interface. The procedure is developed for the case where the ratio, K , of particle characteristic size, a, to the particle's characteristic distance, d , from the interface is much smaller than unity (i.e. K ⪡ 1 ). Situations in which the far fields in each of the two fluids are arbitrary Stokes flow fields are also included in our analysis. Expressions derived for force and torque are in the form of a power series in the ratio K . It is demonstrated that the general results presented here can be easily used to derive explicit expressions for force and torque on any given particle in terms of the fluid and flow properties, as well as certain geometrical properties of the particle, provided the solution to a particle-dependent Fredholm-type surface integral equation is known or obtainable. The utility of the general results in calculating the hydrodynamic resistance of particles is illustrated by the example of an arbitrarily-oriented ellipsoid translating and rotating in a quiescent two-phase fluid. Applications to bodies, such as slender bodies, for which only an approximate solution to the integral equation is available, are also briefly discussed.
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Research Interests:
A six weeks old infant presented with scalp ulcer and fever. and on examination was found to have resonant percussion notes bilaterally. The initial chest radiograph revealed multiple lucencies which were initially thought to be due to... more
A six weeks old infant presented with scalp ulcer and fever. and on examination was found to have resonant percussion notes bilaterally. The initial chest radiograph revealed multiple lucencies which were initially thought to be due to diaphragmatic hernia, but the dilemma was resolved by Computerised tomography which revealed the lucencies to be multiple cysts characteristics of Congenital Cystic Adenomatiod Malformation (CCAM) type II.
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Research Interests:
Research Interests:
KPIM of Gas Transportation: Robust Modification of Gas Pipeline Equations Studies of the flow conditions of natural gases in pipelines have led to the development of complex equations for relating the volume transmitted through a gas... more
KPIM of Gas Transportation: Robust Modification of Gas Pipeline Equations Studies of the flow conditions of natural gases in pipelines have led to the development of complex equations for relating the volume transmitted through a gas pipeline to the various factors involved, thus deciding the optimum pressures and pipeline dimensions to be used. From equations of this type, various combinations of pipe diameter and wall thickness for a desired rate of gas throughput can be calculated. This research work presents modified forms of the basic gas flow equation for horizontal flow developed by Weymouth and the basic gas flow equation for inclined flow developed by Ferguson. The modified equations incorporate non-iterative forms of the Colebrook-White friction factor into the original forms of the Weymouth's and Ferguson's equations. These modified equations thus eliminate the need for iteration in predicting the flow rate of gas through pipelines as is the case with their origin...
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Research Interests:
Abstract The problem of calculating the disturbance due to finite elliptic discs at the interface ( x 3 = 0 ) of two incompressible immiscible fluids of different coefficients of viscosity is solved, assuming that body and inertia forces... more
Abstract The problem of calculating the disturbance due to finite elliptic discs at the interface ( x 3 = 0 ) of two incompressible immiscible fluids of different coefficients of viscosity is solved, assuming that body and inertia forces are negligible. When the direction of motion is parallel to the interface, our solution, which is based on potential functions analogous to the Papkovitch-Neuber functions of linear elasticity, satisfies not only the interface conditions of continuity of fluid velocity and stresses but also that of zero normal velocity at the interface. It is also remarkable that this solution produces in each of the fluids a flow field that is totally independent of the properties of the other fluid. These results are not peculiar to elliptic discs, but also hold for finite discs of other shapes. The method of solution presented here can be readily applied to the more general cases where the two-phase fluid, in the absence of the disc, moves with an arbitrarily directed velocity which is a general polynomial function of the coordinates x 1 and x 2 at the interface. The procedure for carrying this out is demonstrated by treating the case of an elliptic disc in linear shear flow.
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Research Interests:
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The effect of phosphorus on the growth and mineral composition of four tropical pasture legumes—Centrosema pubescens, Centrosema plumeris, Puereria phaseoloides and Stylosanthes gracilis—was investigated in the greenhouse. All the species... more
The effect of phosphorus on the growth and mineral composition of four tropical pasture legumes—Centrosema pubescens, Centrosema plumeris, Puereria phaseoloides and Stylosanthes gracilis—was investigated in the greenhouse. All the species except P. phaseoloides responded to phosphorus application. C. pubescens required more phosphorus for optimum growth than C. plumeris and S. gracilis which required about the same amount. In the species, the potassium, sodium and calcium concentrations in plants given phosphorus seemed higher than that of the control except in S. gracilis where the potassium, and in C.plumeris where the calcium, concentration appeared to be lowered by phosphorus. The concentration of magnesium of C. plumeris seemed to be increased but unaffected in other species by phosphorus addition. Phosphorus tended to depress plant sulphur but it had no effect on percent nitrogen. The percentages of phosphorus, in the species for maximum growth at 65 days from sowing were: C. pubescens, 0.293; P. phaseoloides, 0.228; C. plumeris, 0.280; and S. gracilis, 0.270.
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The effects of macronutrients on nutrient absorption and distribution in cashew have been investigated in sand culture. The absorption and distribution of nutrients were appreciably affected by macronutrients. The type of the relationship... more
The effects of macronutrients on nutrient absorption and distribution in cashew have been investigated in sand culture. The absorption and distribution of nutrients were appreciably affected by macronutrients. The type of the relationship between any two of the nutrients in most cases depended on the plant part considered and the ratio of the concentrations of such nutrients in the nutrient solution. Contrary to the generally accepted views of cation antagonisms, it was found that the relationships among cations were synergistic under certain conditions. In general, it seems that low to moderate doses of any of the macronutrients may be beneficial to cashew in masking the deficiency of one or more of the other nutrients.
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A 7-year-old girl with hypereosinophilic syndrome is described, the first such patient to present with inflammatory bowel disease. Hepatosplenomegaly, anaemia, and hypergammaglobulinaemia were also prominent features. Colonoscopy revealed... more
A 7-year-old girl with hypereosinophilic syndrome is described, the first such patient to present with inflammatory bowel disease. Hepatosplenomegaly, anaemia, and hypergammaglobulinaemia were also prominent features. Colonoscopy revealed a frank colitis of nonspecific histologic appearance. An elemental diet was unhelpful, but there was a prompt clinical and partial haematological response to systemic steroids. She has remained well receiving a small maintenance dose of prednisolone for 3 years.
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An asymptotic scheme is derived for calculating values of the ‘reflected’ Stokeslet-field velocity dyadic V and its gradient ${\boldmath \nabla V}$ back at the Stokeslet location for situations in which this singular point lies in close... more
An asymptotic scheme is derived for calculating values of the ‘reflected’ Stokeslet-field velocity dyadic V and its gradient ${\boldmath \nabla V}$ back at the Stokeslet location for situations in which this singular point lies in close proximity to the wall of an infinitely long circular cylinder. The asymptotic formulas furnished by this scheme permit calculations of first- and second-order wall effects in the non-dimensional parameter κ = a/R0 (a ≡ characteristic particle radius, R0 ≡ cylinder radius) upon the Stokes resistance of a particle of arbitrary shape, location and orientation when translating and/or rotating near the wall of an otherwise quiescent fluid-filled or fluid-surrounded circular cylinder. This reflection-type calculation is applicable for circumstances in which the inequalities κ [Lt ] 1 and 1 − β [Lt ] 1 are each separately satisfied, while simultaneously K/(1 − β) [Lt ] 1. (Here β = b/R0 is the fractionally eccentric Stokeslet location, or equivalently the c...
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Analytical solutions are provided for Stokes flow fields induced by an instantaneous thermal source located (i) in an infinite fluid and (ii) at the center of a solid spherical surface. In both cases it is assumed that the flow is driven... more
Analytical solutions are provided for Stokes flow fields induced by an instantaneous thermal source located (i) in an infinite fluid and (ii) at the center of a solid spherical surface. In both cases it is assumed that the flow is driven by a body force that arises from buoyancy effects in the fluid due to the gradient of the source’s temperature field. In accordance with Stokes approximation, convective acceleration terms are left out of the momentum equations but the local acceleration term is retained. The retention of the local acceleration term is crucial if all the salient features of the flow, especially in its early stages, are to be included in the solution for low Prandtl number. The evolution of the flow field in each of the two cases is demonstrated by plotting streamline patterns at various times. The influence of Prandtl number on flow field development is also discussed. Problem (i) is the fundamental one for this class of problems. From its solution, solutions to pro...
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Research Interests:
In recent times, our experience in the chemotherapy of Burkitt's lymphoma patients in Ibadan, Nigeria has been that of poor outcome, hence this study was undertaken to determine the factors leading to the poor results of... more
In recent times, our experience in the chemotherapy of Burkitt's lymphoma patients in Ibadan, Nigeria has been that of poor outcome, hence this study was undertaken to determine the factors leading to the poor results of chemotherapy of Burkitt s lymphoma in Ibadan. A retrospective analysis of Burkitt s Lymphoma patients seen over eleven year period, between January 1987 to December 1997 at the Paediatrics and Haematology Departments of the University College Hospital, Ibadan was carried out. There were 67 patients, mean age 11+5 years (range 4 to 30 years), 42 males, 25 female giving M:F ratio of 1.7:1. Majority of the patients (76.2%) were stage D, only 4.5% were stages A and of the 67 patients, only 57 (83.6%) had chemotherapy, 40 of whom had COAP, 8 had COMP and 9 patients had either cyclophosphamide or cytosar as monotherapy. Only 22.8% of patients that received chemotherapy went into complete remission. In this study, we observed a declining overall complete remission rate of 22.8% (compared to 47% in 1979) in Burkitt s Lymphoma patients. The presence of large amount of fake drugs in the Nigerian market may imply that some of the cytotoxic drugs used in these patients could have been fake drugs. We suggest that the government should subsidize the therapy of these patients as well as eradicate the presence of fake drugs in the market, thereby increasing the chances of a cure.
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Research Interests:
It is shown that the potential functions which determine the elastic fields in a two-phase elastic material when both phases are transversely isotropic or when either of the phases is transversely isotropic and the other is isotropic, can... more
It is shown that the potential functions which determine the elastic fields in a two-phase elastic material when both phases are transversely isotropic or when either of the phases is transversely isotropic and the other is isotropic, can be deduced from the corresponding potentials for an infinite homogeneous solid. The material of this infinite homogeneous solid, from whose solution one
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When a point source explosion is initiated at the ocean surface, the shock propagated into the water is reflected at the surface as a centered expansion wave. The solution in the neighborhood of the interaction point is obtained by... more
When a point source explosion is initiated at the ocean surface, the shock propagated into the water is reflected at the surface as a centered expansion wave. The solution in the neighborhood of the interaction point is obtained by writing the equations of motion in the appropriate similarity variables and then changing the independent variables to polar coordinates based at
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Childhood primary hepatocellular carcinoma is rare and accounts for less than 1% of all abdominal malignancies in children < or = 14 years of age. A review of the records of the Cancer Registry, Ibadan, Nigeria covering the... more
Childhood primary hepatocellular carcinoma is rare and accounts for less than 1% of all abdominal malignancies in children < or = 14 years of age. A review of the records of the Cancer Registry, Ibadan, Nigeria covering the period 1960-1995 was scrutinised and 19 cases of hepatocellular carcinoma (HCC) were registered, accounting for 0.49% of all abdominal malignancies over the period of review. The mean (SD) age at presentation was 10.4 (3.0) years and the duration of illness before presentation was short. All the children presented late with abdominal distension and hepatomegaly as the major clinical features. Weight loss was evident in 80% of cases, splenomegaly occurred in 50% and jaundice was present in a third of them. The prognosis was poor; all the cases died within 2 weeks of presentation in hospital. There was evidence to suggest an association between hepatitis B virus infection and HCC in all the liver tissue stained by Shikata-Orcein. This review shows that HCC, though uncommon, is important enough to be considered a possible cause of unexplained hepatomegaly in Nigerian children and that hepatitis B virus is an important aetiological factor. Though the number of cases under review is small, universal early vaccination against hepatitis B virus is necessary in Nigerian children in order to reduce the burden of chronic hepatitis B disease and hepatocellular carcinoma.
Research Interests: Nigeria, Adolescent, Medicine, Humans, Child, and 14 moreFemale, Male, Hepatocellular Carcinoma, Infant, Incidence, Registries, Clinical Sciences, Public health systems and services research, Hepatomegaly, Retrospective Studies, Prognosis, Child preschool, Liver neoplasms, and Paediatrics and reproductive medicine
One hundred and eight children with acute, symptomatic, uncomplicated, falciparum malaria were randomized to receive chloroquine (for 3 days) plus chlorpheniramine alone (for seven days) (CQ-CP group; N = 55) or, in a sequential... more
One hundred and eight children with acute, symptomatic, uncomplicated, falciparum malaria were randomized to receive chloroquine (for 3 days) plus chlorpheniramine alone (for seven days) (CQ-CP group; N = 55) or, in a sequential treatment, chloroquine plus chlorpheniramine for 3 days followed, on the fourth day, by a single oral dose of sulfadoxine-pyrimethamine (25 mg sulfadoxine/kg) (CQ-CP-SP group; N = 53). The mean (S.D.) parasite-clearance time in the CQ-CP group [2.1 (0.7) days; range = 1-5 days] was similar to that in the CQ-CP-SP [2.1 (0.8) days; range = 1-5 days]. The fever-clearance times were also similar: 1.2 (0.1) days (range = 1-3 days) v. 1.1 (0.4) days (range = 1-3 days). The cure rates on days 14, 21 and 28 were 98.2%, 96.3% and 92.7%, respectively in the CQ-CP group, and 100%, 100% and 96.2%, respectively, in the CQ-CP-SP group. The rates of gametocyte carriage were low and similar (5.4% in the CQ-CP group and 3.8% in the CQ-CP-SP group) throughout the duration of the study. Both treatment regimens were relatively well tolerated, the main adverse reactions being similar: sleepiness (on day 1) and pruritus (on days 1-3). No adverse effect was attributable to SP. The results indicate that sequential treatment, for 3 days with CQ and CP, followed by a single dose of SP, is effective and well tolerated in children with acute, uncomplicated, falciparum malaria and may be an alternative treatment for CQ- and/or SP-resistant falciparum malaria. Treatment with a CQ-CP combination (CQ and CP for 3 days and then CP alone for another 4 days) is also effective but requires continuing administration after the signs and symptoms of acute malaria have disappeared.
Research Interests: Medical Microbiology, Treatment Outcome, Humans, Child, Germ Cells, and 13 moreAnimals, Infant, Clinical Sciences, Pyrimethamine, Sulfadoxine, Fever, Public health systems and services research, Plasmodium falciparum, Antimalarials, Combination drug therapy, Chloroquine, Child preschool, and Malaria Falciparum
The clinical characteristics and the responses to oral antimalarial therapy of 104 children presenting consecutively with or without Plasmodium falciparum hyperparasitaemia (HP) were investigated in an endemic area. At presentation,... more
The clinical characteristics and the responses to oral antimalarial therapy of 104 children presenting consecutively with or without Plasmodium falciparum hyperparasitaemia (HP) were investigated in an endemic area. At presentation, although the 52 children with HP were significantly younger and had significantly higher heart rates than the 52 without, there were no significant differences between the two groups in their symptoms or in any other clinical feature of their malaria. Responses to oral antimalarial drugs were similar in both groups. Analysis of the disposition kinetics of parasitaemia, using a non-compartmental model similar to that used in characterizing drug disposition, showed that the two groups had similar half-lives of parasitaemia (t1/2pd), volumes of blood completely cleared of parasites per unit time (CLBpd), and parasite-clearance-time:t1/2pd ratios. Three children in the HP group, all aged < 3 years, progressed to cerebral malaria within 8 h of presentation, and another HP child presented with isolated trunkal ataxia, indicative of cerebellar involvement. No child in the non-HP group had any of the features of severe malaria. Although the clinical characteristics and responses to oral therapy of children with and without HP are therefore very similar, young children with HP appear to have an increased risk of developing other features of severe malaria.
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The increasing resistance of Plasmodium falciparum to chloroquine (CQ) has created an urgent need for the evaluation of alternative, effective, safe, cheap, readily available and affordable antimalarial treatments. In the present study,... more
The increasing resistance of Plasmodium falciparum to chloroquine (CQ) has created an urgent need for the evaluation of alternative, effective, safe, cheap, readily available and affordable antimalarial treatments. In the present study, the efficacy of amodiaquine (AQ) in the treatment of acute, symptomatic, uncomplicated, P. falciparum malaria was compared with that of CQ, each drug being given at 10 mg/kg per day for 3 days (days 0, 1 and 2). The 210 subjects (104 given AQ and 106 CQ) were Nigerian children aged 5 months-12 years. Fever-clearance times (FCT), parasite densities on days 1-4 and parasite-clearance times (PCT) were all significantly lower with AQ than with CQ. Mean (S.D.) PCT, for example, were 2.6 (0.8) days with AQ and 3.0 (1.0) days with CQ (P = 0.001). The cure rates obtained on days 14, 21 and 28 - 98.1% v. 79.3% (P =0.000), 97.1% v. 64.2% (P = 0.00001) and 95.2% v. 58.5% (P = 0.0000000) with AQ and CQ, respectively - were all also significantly higher with AQ. All but two of the 20 subjects who were considered CQ-treatment failures by day 14 (i.e. two RIII, two RII and 16 RI) responded to subsequent treatment with AQ, with PCT (but not FCT) significantly shorter than during their initial treatment with CQ. In siblings in whom there was clustering of infections, the cure rates were 100% with AQ (N =12) and 63.6% with CQ (N = 11; P = 0.03). Adverse reactions to CQ and AQ were similar and tolerable: pruritus in 10 and 11 children in the AQ and CQ groups, respectively, and gastro-intestinal disturbances which occurred in three children from each group. Haematological parameters were not adversely affected by either drug. At least in the setting of the present study, AQ appears more effective than CQ, effective against CQ-resistant infections, and well tolerated by children with acute, uncomplicated, P. falciparum malaria. It may therefore be useful as an alternative to CQ in areas of CQ resistance.
Research Interests: Nonparametric Statistics, Medical Microbiology, Nigeria, Medicine, Humans, and 15 moreChild, Female, Drug Resistance, Male, Infant, Endemic Diseases, Clinical Sciences, Analysis of Variance, Antimalarials, Age Factors, Combination drug therapy, Chloroquine, Amodiaquine, Child preschool, and Malaria Falciparum
Factors affecting the course of asthma are not clearly understood in rural and urban communities within low-resource countries. Furthermore, the interactions between atopy, environmental exposure, and helminthic infections in modulating... more
Factors affecting the course of asthma are not clearly understood in rural and urban communities within low-resource countries. Furthermore, the interactions between atopy, environmental exposure, and helminthic infections in modulating asthma have not been well investigated. To conduct a feasibility study to examine the relationship between atopy and asthma in adults at two rural Health Centers and urban university college hospital in southwestern Nigeria. A convenient sample of 55 consecutive patients with stable physician-diagnosed asthma and 55 age-matched nonasthmatic controls seen at the outpatient clinics in two rural Health Centers and an urban university hospital were enrolled. All subjects underwent blood test, allergy skin test, and stool examination for ova and parasites. Wilcoxon sign-rank tests were used to compare serum eosinophilia and allergy skin test between the two groups. Asthmatics in both urban and rural settings had significantly more positive skin reactions to house dust mite, cockroach, mold, and mouse epithelium than nonasthmatic controls (p < .05). Mean total serum IgE was also significantly higher in asthmatics than in nonasthmatic controls (360 vs. 90 IU/L, p <.001). Stool parasitemia was infrequent in both groups and not statistically significant. Atopy is associated with adult asthma in southwest Nigeria. Larger studies to confirm the nature of this association and to examine the role of helminthic infection and other environmental factors on the expression of asthma are needed.
Research Interests: Asthma, Nigeria, Urban Health, Rural Health, Humans, and 5 moreFemale, Male, Clinical Sciences, Adult, and Hypersensitivity
Pediatr Infect Dis J, 1994;13:975-82 0891-3668/94/$03.00/0 Copyright © 1994 by Williams & Wilkins Vol. 13, No. 11 Printed in USA The etiology of pneumonia in malnourished and well-nourished Gambian children RICHARD A. ADEGBOLA, PHD,... more
Pediatr Infect Dis J, 1994;13:975-82 0891-3668/94/$03.00/0 Copyright © 1994 by Williams & Wilkins Vol. 13, No. 11 Printed in USA The etiology of pneumonia in malnourished and well-nourished Gambian children RICHARD A. ADEGBOLA, PHD, ADEGOKE G. FALADE, FMCPAED, ...
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Research Interests:
To determine vitamin A status by conjunctival impression cytology with transfer (CIC-T) and assess its ability to predict low and deficient serum retinol concentrations. CIC-T was performed on 128 healthy, well-nourished and 230... more
To determine vitamin A status by conjunctival impression cytology with transfer (CIC-T) and assess its ability to predict low and deficient serum retinol concentrations. CIC-T was performed on 128 healthy, well-nourished and 230 malnourished children aged under 6 years by a 3-5-second application of cellulose acetate paper to each bulbar conjunctiva followed by transfer of the adhered cells onto glass slides. The slides were stained with Alcian green 2GX, and smears were classified as normal, borderline normal, borderline abnormal and deficient. Corresponding serum retinol levels were determined in each subject. The results showed that CIC-T is a simple procedure with a failure rate of 7.3% caused by tearing and agitation. The power of CIC-T to predict vitamin A status varied with both the CIC-T smear classification used and serum retinol concentration threshold. CIC-T smear classification as abnormal and normal appears to be the most robust and predictive of serum retinol, < 10 and > 10 < 20 micrograms/dL, respectively. The simplicity, sensitivity and specificity of CIC-T suggest that this procedure is a good screening tool for epidemiologic survey of vitamin A status.