Showing papers by "University of Zambia published in 1978"

Linear model reduction using Hurwitz polynomial approximation

Abstract: A new approach to stable reduced-order linear model construction is given, based on the concept of Hurwitz polynomial approximation. Pade approximants to the tangent function of a given large-degree Hurwitz polynomial are constructed, such that the corresponding low-degree polynomials are also Hurwitz. We prove a theorem to that effect and give methods for obtaining the reduced Hurwitz polynomials. Model reduction is achieved by first invoking this theorem and completing the reduction using the Pade equations. Two examples are given.

White farmers, black tenants and landlord legislation: Southern Rhodesia 1890–1930

Abstract: The theme of this paper is the array of legislation controlling African tenancy on white-owned farmland. This legislation spread from South Africa (the Cape, 1869; Natal, 1896; Transvaal, 1887; Orange Free State, 1893; Southern Rhodesia, 1908; Nyasaland, 1917; Kenya, 1918). In each case, the legislation had a common purpose-to deny to Africans use of white-owned land, except in the capacity of labourers. In each case, the form the legislation took, although derived from South African practice, was determined by the particular constellation of forces in the political economy at the time. The core of this study is an examination of the Southern Rhodesia Private Locations Ordinance of 1908, and of its application. There are three levels of discussion. At the regional level, I have drawn on recent published and on some unpublished material which seems to me to be worth bringing together. At the level of white Rhodesian politics, I have looked in more detail at the manipulations which went into the making and implementation of the legislation. And at the local level, I have examined its implementation in one particular district, MelsetterChipinga, in the south-east of what was formerly Southern Rhodesia. Labour tenancy was a relation of serfdom which emerged wherever white farmers with limited capital took land from agricultural peoples. It is argued in this essay that in the colonial context it was inherently an unstable relation of production. The development of capitalism in urban, rural and mining areas tended to undermine all forms of tenancy, and tended to create landless proletariats, both urban and rural. But while an effective attack was mounted on other forms of African tenancy on white-owned land, white farmers, by virtue of their disproportionate influence in the

Thermal acclimation in temperate lizards

Abstract: THERMAL acclimation has been studied most intensively in aquatic ectotherms1 in which body temperature closely approximates water temperature, which changes slowly with season. As aquatic ectotherms must therefore be active over a range of slowly changing body temperatures, acclimation usually functions as a homeostatic mechanism; following a temperature change in the environment, the organism's metabolic rate is adjusted so that it is returned to near its original level2. Some terrestrial animals, particularly reptiles which thermoregulate behaviourally, are subject to considerable daily fluctuations in body temperature3. This difference in the thermal ecology of aquatic ectotherms and terrestrial reptiles, which may cause a difference in the acclimatory responses of the two groups, has not been considered in the work on thermal acclimation in reptiles4–6. Consequently, this work is of little use in predicting the acclimatory responses of reptiles to seasonal temperature changes in the field. We present here evidence that lizards allowed to thermoregulate behaviourally acclimate only at low body temperatures and that the common pattern of acclimation differs from that of aquatic organisms in being determined by requirements of low temperature energy conservation rather than metabolic homeostasis.

Tawani, Machambero!: Forced Cotton and Rice Growing on the Zambezi

Abstract: Between 1935 and 1960 a peculiar patterning of forced labour developed on Mozambique's lower Zambezi. By the beginning of the Salazar era a particular style of history had been imprinted upon Mozambique. Large scale recruiting of labour for the mines and farms of southern Africa coupled with mass migrations of Mozambique's people to escape the oppressions of Portuguese administration resulted in a severe labour shortage which companies operating in the colony had to face. Exacerbating this problem was the Portuguese decision in the mid-1930s to compel the colonies to produce enough cotton for the demands of the empire. To protect its position vis-à-vis already scarce male labour, the Sena Sugar Estates Ltd., Mozambique's largest employer of labour, formulated a system by which only female labour would cultivate cotton, leaving the men free to work in the company's sugar fields. This system, which was adopted in the 1940s by other employers of labour, led to severe oppression of the local people, notably the women, who were caught between the conflicting demands of interests more powerful than themselves. Only in the late 1950s and early 1960s did the pressures of the forced cultivation system end.

Suicide rates in Lusaka, Zambia: preliminary observations

Abstract: The records of all suicides and of all open verdicts in Lusaka (Zambia) over a 5-year period (1967–1971) were studied. The following suicide rates (per 100000 of the population per annum) were found: 7·4 for all races; 11·3 for men of all races; 3·0 for women of all races; 6·9 for all African residents; 11·2 for African males; 2·2 for African females; 12·8 for all Africans above the age of 14 years; 20·9 for all European residents; 20·7 for all European males; 21·0 for all European females. The male: female ratio among the Africans was 5:1. There was a tendency for the suicide rate among the Africans to rise with age. Differences in suicide rates between African and European residents were found not to be statistically significant. Though hanging was by far the most commonly used method of suicide by Africans, Europeans and ‘doubtful suicides’ among Africans preferred other methods to a statistically significant degree. It is suggested that the role of other methods in African suicides may well have been underestimated in the past. No definite seasonal variation in suicide rates was found. Domestic quarrels, mental illness and physical diseases would appear to be some of the important precipitating factors of suicide in Lusaka. It is also suggested that the question of whether or not suicide is rare in Africans cannot be answered until such time as when reliable figures are available in Africa.

Geese and Red-knobbed Coot on the Kafue Flats in Zambia, 1970–1974

Abstract: Summary The occurrence, chronology of breeding and wing-moult, and feeding habits of the Pigmy Goose Nettapus auritus, Knob-billed Goose Sarkidiornis melanotos, Spur-winged Goose Plectropterus gambensis, Egyptian Goose Alopochen aegyptiaca and Red-knobbed Coot Fulica cristata on the Kafue Flats in Zambia are described based on observations made between October 1970 and January 1974 at Lochinvar National Park and, from the air, over the central section of the Flats. The Pigmy Goose, Knob-billed Goose, Egyptian Goose and Red-knobbed Coot fed largely by grazing. They were most abundant between March and June, occurring in greatest numbers at Lochinvar. Egyptian Geese occasionally nested on the flood-plain at Lochinvar between August and January, but there was no proof of the other species nesting there. Many Pigmy Geese and male Knob-billed Geese moulted on the lagoon at Lochinvar between March and June; small numbers of Egyptian Geese and Red-knobbed Coot also moulted in the Park, the former between February and May, the latter in June and July. The Spur-winged Goose fed mostly by grazing and grubbing. Numbers on the Flats were greatest between June and November when 60,000–90,000 moved downriver as the floods subsided. Many bred between January and March in the fringing zone and moulted on the floodplain between May and July. A hydroelectric scheme, completed in 1975, may benefit the Pigmy Goose and Red-knobbed Coot but harm the Spur-winged Goose.

In situ magnetic measurements on igneous rock bodies

Abstract: A simple method for an in situ measurement of susceptibility and low-field hysteresis on rock bodies like dykes and flows is described. Extensive use of this method indicates that in some dykes and flows, the nature of the magnetic grains varies rapidly across the bodies. Making use of such observations, it seems possible to select stable rock samples for palaeomagnetic work and also understand to some extent the origin of remanent magnetization in different types of rock bodies.

Soviet Marxism and African Socialism

Abstract: In the last few years, there has been a sharp upsurge in the popularity of Marxism among intellectuals in African countries. The earlier African ideologies - ujamaa, humanism, negritude – with their softer, reconciliatory attitudes, and their stress on brotherhood rather than class struggle, have lost some of their appeal for progressive or radical African intellectuals. The reasons for this decline are fairly obvious. The early progressive ideologies are all now associated with governments in power, thus with the status quo, and cannot become the motivating force for those desiring change.

Experimental immunity against trypanosomiasis.

Abstract: 9 groups of 6 female rats were used in an experiment using fraction 3 ofTrypanosoma rhodesiense. 500 μg gave 100% immunoprotection and 1000 and 1500 μg gave 66% immunoprotection when challenged with 5×102T. brucei. 2 groups of 10 female rats were tested for a short period inoculation immune response. In this, 750 μg of fraction 3 ofT. rhodesiense gave 70% immunoprotection when challenged withT. brucei.

Expectations unfulfilled: the under‐development of peasant agriculture in Zambia: the case of Kabwe rural district, 1964–1970

Abstract: This paper springs from a broader project of research into the rural underdevelopment of Zambia. In order to understand this underdevelopment from within, I focused on a particular district-the area which came to be known under colonial rule as Broken Hill Rural District and after Independence as Kabwe Rural District. I enriched my archival sources by many oral interviews, documenting the experience of the informants under colonialism and after Independence in 1964. 1 1 have drawn extensively upon these interviews for this paper since they constitute, in the absence of any effective statistical record of African peasant production, the only means of assessing the socio-economic changes that took place after Independence and the producers' reaction to them. In my broader project, I argued that rural underdevelopment can only be understood within the context of capitalist labour resource demands over the last hundred years and that what has happened after Independence cannot be fully appreciated outside this framework. In the context of this article, it is not appiopriate to spend too long on the pre-Independence developments, but a brief summary is essential. From such a summary, it will appear clearly enough that African agriculture was systematically underdeveloped; that African producers understood and resented this; and that high hopes were placed in the 'nationalist' solution. The history of production in Kabwe Rural District since its contact with capitalism has been largely one of conflict between African peasant

Depth Estimation from Residual Bouguer Anomalies: a Procedure Based on the Backus-Gilbert Minimum Distance Criterion *

Abstract: The minimum distance criterion of Backus and Gilbert is used to determine the depths of line masses approximating the subsurface two dimensional distribution of density differences responsible for the observed residual Bouguer anomaly values. The quantity minimized is the sum of the squared differences between the starting trial depths and the desired final depths of line masses. The search for the desired depths is limited to preset depth ranges.