Showing papers by "University of Zambia published in 1979"
TL;DR: The results are interpreted as suggesting that cross-cultural differences in performance of pattern reproduction tasks reflect different sets of highly specific perceptual skills rather than differences on broader cognitive variables such as practical intelligence, field-dependency or sensotypes.
Abstract: Pattern reproduction tasks were presented in four different media to samples of urban Zambian and urban British schoolchildren. When the patterns were reproduced as wire models, the Zambian children excelled the British. When the patterns were reproduced by drawing, the British children excelled the Zambian. No reliable cross-cultural differences were found when the patterns were reproduced as plasticine models or as configurations of hand positions. Both cultural groups were equally adversely affected when required to perform the modelling tasks or the hand positions task blind-folded. The results are interpreted as suggesting that cross-cultural differences in performance of pattern reproduction tasks reflect different sets of highly specific perceptual skills rather than differences on broader cognitive variables such as practical intelligence, field-dependency or sensotypes.
203 citations
TL;DR: One group of insects, the bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae), are less host-specific in the tropics than in temperate regions, even though there are considerably more species present in the Tropics.
Abstract: Many groups of animals show a gradient of increasing species richness from polar to equatorial regions1,2. Theory3,4 suggests that species should be more specialised ecologically in the tropics. Most of the evidence for this comes from studies on birds5–10. Birds appear to subdivide the habitat more finely and specialise more in their food in the tropics. It has been suggested11 that tropical Papilionidae (Lepidoptera) are more specialised in their hosts than temperate species, but host specificity was considered only at the level of the plant family, and more detailed studies of a wide range of butterflies12 suggest that they are little (if at all) more specialised in their food plants in the tropics. Similarly, monogenean trematode parasites of fish show no change in the degree of host specificity at different latitudes13. Here it is shown that one group of insects, the bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae), are less host-specific in the tropics than in temperate regions, even though there are considerably more species present in the tropics. The ‘reverse’ latitudinal gradient in host specificity can be related to the greater proportion of relatively non-specific xylomycetophagous species (ambrosia beetles) in the tropics and to the greater heterogeneity of tropical forests which will make host specialisation more difficult.
162 citations
Abstract: Two Pade methods are discussed for constructing low-degree Hurwitz polynomials from a given high-degree Hurwitz polynomial to approximate its argument. Using the Hurwitz polynomial approximants as characteristic polynomials, the numerator dynamics of reduced-order (matrix) transfer-function models are then easily determined by partial Pade approximation of a given large-order model. Stability of such reduced models is always assured. By suitable linear fractional transformations the methods are made applicable to discrete-time systems. The methods are compared in simulation examples for both continuous and discrete-time systems.
46 citations
Federal University of Bahia1, Siriraj Hospital2, Post Graduate Institute of Medical Education and Research3, University of Western Ontario4, University of Southern California5, University of Zambia6, University of Chile7, Seoul National University8, National University of Singapore9, Karolinska University Hospital10, University of Sydney11
TL;DR: Variations in metabolism of orally administered norethisterone appeared not to be due to variations in body size, and was of the same order as the intra-centre differences.
25 citations
TL;DR: Examination of a small sample of lechwe revealed that animals less than one year old had pure infections of S. margrebowiei and those over five years old had S. leiperi only, suggested that these findings are related to the different habitats occupied by the snail hosts for the two parasites and the annual movements of the le chwe herds in response to the local flood cycle.
Abstract: Summary Natural infections of Schistosoma margrebowiei were found in Bulinus forskali group snails (B. forskali and B. scalaris) at Lochinvar National Park, Zambia. This is the first record of a natural snail host for this species. The most abundant host in the Park for S. margrebowiei and S. leiperi is the lechwe (Kobus leche). Examination of a small sample of lechwe revealed that animals less than one year old had pure infections of S. margrebowiei and those over five years old had S. leiperi only. It is suggested that these findings are related to the different habitats occupied by the snail hosts for the two parasites and the annual movements of the lechwe herds in response to the local flood cycle. The possibility of some cross-immunity between S. leiperi and S. margrebowiei is discussed.
12 citations
12 citations
TL;DR: In this article, a comparison is made between cement roofing sheets reinforced with asbestos fibres, elephant grass and sugar cane residue on the basis of some physical and mechanical properties and derived costs.
11 citations
01 Dec 1979
2 citations
TL;DR: In adult male rats, bilateral intratesticular administration of 20 μg PGA1 or 20 μg indomethacin significantly reduced the acute stimulation of plasma testosterone levels by concomitantly injected LH, while treatment with the same dose of PGF2α was without effect.
Abstract: In adult male rats, bilateral intratesticular administration of 20 μg PGA1 or 20 μg indomethacin significantly reduced the acute stimulation of plasma testosterone levels by concomitantly injected LH, while treatment with the same dose of PGF2α was without effect. After six days of treatment with indomethacin, plasma testosterone levels were reduced to approximately 1/3 of the control levels.
Intratesticular administration of 10 μg LH per testis per day produced, after six days, a precipitous decline in plasma testosterone levels and a decrease in the weight of the testes. This was probably due to desensitization of Leydig cells by these high doses of gonadotropin. Administration of PGF2α together with LH caused a further decrease in testicular weight and a significant reduction in the weights of the prostate and the seminal vesicles.
1 citations
TL;DR: The author examines the role of geographical and historical processes in village population changes in western Sierra Leone as an example, with particular emphasis on the impact of migration.
Abstract: The author examines the role of geographical and historical processes in village population changes in western Sierra Leone as an example with particular emphasis on the impact of migration. Both official census and unpublished data are used. Changes in population settlement over the period 1911 to 1963 are reviewed (ANNOTATION)
1 citations
TL;DR: In this paper, the flexural vibrations of a thin elastic plate with variable rigidity and having the form of a sector of a circular ring have been investigated and an approximate solution has been obtained for the case of a plate having clamped radial edges and the circumferential edges having any combination of boundary conditions.
Abstract: The present note is concerned with the flexural vibrations of a thin elastic plate with variable rigidity and having the form of a sector of a circular ring. Plates of this shape have been rather sparsely treated in the literature. The problem of free vibration of sectorial plates with radial edges simply supported has been investigated by Ramiah and Vijaykumar and by Ramakrishnan and Kunnukkasseril. For the case of a plate having clamped radial edges and the circumferential edges having any combination of boundary conditions, an approximate solution has been obtained by Bhattacharya. The free vibration of annular plates for various boundary conditions are summarised by Leissa. All these are for plates of constant thickness only.
TL;DR: A statistically significant reduction was noted in both systolic and diastolic blood pressures whilst on active treatment and treatment with a spironolactone-althiazide combination did not influence serum potassium or creatinine levels.
Abstract: SummaryA clinical trial was carried out to compare the eflects of placebo and of a spironolactone-althiazide combination in the treatment of 24 Zambian Africans with hypertension. After an initial 2 weeks on placebo, patients received 100 mg spironolactone plus 60 mg althiazide daily for 12 weeks. They were then treated with placebo again for 3 to 5 weeks, followed by a second active treatment period of 6 to 8 weeks in dosages ranging from 50 mg spironolactone plus 30 mg althiazide to 150 mg spironolactone plus 90 mg althiazide according to the previous response. A statistically significant (p <0.001) reduction was noted in both systolic and diastolic blood pressures whilst on active treatment. Mean reductions were 30/16 mmHgfor supine and 35/21 mmHg for standing blood pressures. Treatment with the combination product did not influence serum potassium or creatinine levels. Mean blood urea, however, increased from 23.6 to 35.1 mg/100 ml and the mean serum uric acid from 6.7 to 8.9 mg/100 ml. No serious sid...
TL;DR: It is felt that, in developing countries at least, treatment of pyogenic meningitis in children should be with penicillin-chloramphenicol combinations, but where rapid and accurate bacteriology is available amoxycillin may be a valuable non-toxic alternative to chlorampshenicol with similar activity to ampicillin.
Abstract: An open trial of the use of amoxycillin injection in the treatment of pyogenic meningitis in children showed similar results to previous trials here of penicillin-chloramphenicol combinations. It is felt that, in developing countries at least, treatment of pyogenic meningitis in children should be with the latter combination, but where rapid and accurate bacteriology is available amoxycillin may be valuable non-toxic alternative to chloramphenicol with similar activity to ampicillin.