College of Agriculture, Engineering and Science
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Item Item Item The alkaloids of the Amaryllidaceae : the isolation and structures of two new alkaloids from Haemanthus natalensis and Nerine krigeii and contributions to the chemistry of coccinine : the absolute configuration of alkaloids based on the 5:10b-Ethanophenanthridine nucleus.(1960) Jeffs, P. W.; Warren, Frank Louis.No abstract available.Item An experiment in land use mapping in the Three Rivers District, Natal.(1965) Christopher, Anthony John.; Davies, Ronald John.; Biesheuvel, H.No abstract available.Item The herpetology of south-east Africa.(1966) Broadley, Donald George.; Poynton, John Charles.No abstract available.Item Field and model studies of the nearshore circulation.(1967) Harris, Thomas Frank Wyndham.Investigations into the characteristics and underlying mechanism of the circulation of water near the shore are reported. The two main types of circulation, one a cellular system resulting from Haves propagated nearly normally to the shore, and the other an essentially alongshore flow associated with oblique waves, are treated separately. The cellular circulation studies were made in the field at Virginia Beach and more extensively in wave tanks. From the field experiments data were collected about the dimensions of the cells, the way in which the Hater circulated, the rate of exchance of surf zone water and the extent of recycling. A method for measuring the changes in the mean sea level over intervals of time greater than those of the wave periods, was developed. The model experiments carried out in uniform wave tanks showed that the cellular circulations could be well simulated. Measurements were made of the cell dimensions, the velocity of the longshore and rip currents, and of the recycling regime. A finding from the wave tank studies Has the presence of standing waves formed by transverse edge waves. The interaction of these standing waves with the gene rated waves normal to the shore could be the initial cause of rip currents and the cellular circulation. Studies of the alongshore system were made in the field only. A method for measuring the volume of flow of longshore currents was developed, tested, and applied. Calculated volumes of flow using a theory based on continuity and the solitary wave theory (as proposed by Inman and Bagnold) compared tolerably well with the field observations. The calculations of volume of flow required a knowledge of the wave height spectra in the surf. This was established by making wave height recordings in the between-breaker zone . It was found that the characteristics of the spectra compared reasonably well with those pr e dict ed by the Longuet-Higgins theory, previously assumed to apply to deep water waves only. A mechanism for the transition from cellular to alongshore system is proposed.Item Some aspects of the role of rat liver ribosomes in protein biosynthesis.(1969) Nourse, Leonard Donald.; Quicke, George Venn.No abstract available.Item The isolation of a toxic factor from a local cultivar of Phaseolus vulgaris, and an assessment of its relation to growth depression.(1969) Stead, Robin Hugh.; Quicke, George Venn.No abstract available.Item Natal : a study in colonial land settlement.(1969) Christopher, Anthony John.; Davies, Ronald John.No abstract available.Item Tissue culture studies on the genus Rosa with special reference to the shoot tip.(1969) Jacobs, Gerard.; Allan, P.; Bornman, Chris H.A modified Berthelot (1934)-Knop (1865) solution was found to support the growth of rose pith segments while Murashige and Skoog's (1962) medium did not. Possibly the NH(4)+ content of the latter medium is toxic to rose tissue. The best callus growth was obtained with indolebutyric acid (IBA), which was superior to naphthaleneacetic acid (NAA), indoleacetic acid (IAA) and 2,4 dichlorophenoxybutyric acid (2,4-DB) at the concentrations tested, while gibberellic acid (GA) greatly enhanced callus formation in the presence of both IBA and kinetin. Occasional differentiation of shoots was observed both in cultured pith segments and in callus formed at the basal cut surface of the shoot tips. However, the precise culture conditions required for differentiating rose pith and callus tissue remain unknown. An interaction was found between NAA and kinetin with regard to root and leaf development in shoot tips. Root formation took place only in the absence of kinetin and in the NAA range of 0.5 to 2.0 mg/l, while normal leaf development occurred only in the absence of NAA and in the presence of 4.0 to 18.0 mg/l kinetin. Neither any combination of NAA and kinetin nor the sequential application of growth substances induced both root and shoot growth. Furthermore, shoot tips sampled in late summer formed roots much more readily than tips sampled in late winter. GA reduced the favourable effect of high kinetin treatments on leaf development. Different species of auxin affected growth of the shoot tip in different ways. IAA did not inhibit growth of the shoot tip in the same manner as was observed for NAA, IBA and 2,4 dichlorophenoxybutyric acid (2,4-D). It is concluded that further experimentation with different ratios of various species of auxin and cytokinin, as well as the sequential administration of growth substances, may lead to the successful culture of intact plantlets from rose shoot tips and shoot apical meristems, and ultimately to possibly virus-free rose plants.Item Abscisic acid and other hormonal effects on growth in Spirodela.(1969) Van Staden, Johannes.; Bornman, Chris H.The effects of abscisic acid In particular, as well well as gibberellic acid and the cytoklnlns, 6-benzyladenine, kinetin, and 6-dlmethylal lalylamlnopurine, on the growth of Spirodela oligorrhiza were investigated. Abscisic acid effectively arrested growth permanently at concentrations down to 10¯¹ mg/I. Normal growth tended to be resumed at concentrations of 10¯² and 10¯³ mg/l between nine and twelve days after treatment. A concentration of 10[-8] mg/l, however, resulted in a significant increase in dry weight at both eight, nine and twelve days after introduction into the culture medium. It is suggested that the resumption of growth twelve days after treatment at those concentrations which inhibit growth up to nine days, was due to a possible progressive inactivation of abscisic acid resulting in a lowering of its concentration to a level that is promotive. It was furthermore found that the growth response of Spirodela in terms of dry weight production over a period of eight days is proportional to the log[10] concentration of abscisic acid. It is suggested that this curve can be used as a relatively reliable and easily performed bioassay to detect amounts of abscisic acid as low as 10[-5] μg. The assay is more reliable over the range 0.01 to 10,000 μg and appears not to be affected by gibberellin, benzyladenine and kinetin. The inhibitory effect of abscisic acid on growth in Spirodela was shown to be reversed by benzyladenine, kinetin and dimethylallalylaminopurine, although they were not equally effective in doing so. Benzyladenine at 1.0 mg/l was the most effective In overcoming growth inhibition by abscisic acid. Gibberellic acid, however, proved ineffective in reversing the inhibitory effect of abscisic acid on Spirodela oligorrhiza. The apparent Increases in growth obtained in some cases may have resulted more directly from gibberellic acid stimulation than from the Interaction of gibberel lie acid with abscisic acid.Item The chemistry of river waters with special reference to the rivers of Natal.(1969) Kemp, P. Hayden.No abstract available.Item Aspects of the morphology and bionomics of Batrachomorphus cedaranus (Naude) and Lygidolon laevigatum Reut. on black wattle (Acacia mearnsii De Wild)(1970) Connell, Allan Donovan.; Oosthuizen, Marguerite Poland.; Hepburn, G. A.No abstract available.Item Intersex in four South African racial groups in Durban.(1970) Grace, Hatherley James.; Bain, Peter G.Chapter I The ontogeny of sex development is introduced and a definition of the intersexual state is given. A resume of intersexes recorded in South Africa is presented together with figures showing the increased demand for cytogenetic services in the country. The motivation for this study is discussed. Chapter II The biological concept of sex is outlined together with notes on the evolution of the dioecious state in animals. Thereafter a brief account of the normal and abnormal intersex states in invertebrates and vertebrates is given. Chapter III Examples of some of the abundant references to ambisexual individuals found in the classical literature, history and mythology are listed and the status of intersexes in modern society is discussed: it does not vary much from the times of ancient Greece and Rome. Chapter IV A summary of the events which led to the establishment of cytogenetics as an independent discipline is given. The discovery of nuclear sex dimorphism is noted and methods of investigation of intersexual patients are described. A detailed description is given of cytogenetic technical. "methods, ; and leads to a diagrammatic explanation of the differential diagnosis of intersexes. This is used as a basis for the classification and accordingly a simplified, unambiguous system is proposed and defended. The sources and numbers of pat~ ients recorded in this thesis are explained. Chapter V The sex chromatin is described in detail? with a description of the methods used for its demonstration and evaluation. A pilot study of normal women of the four races established that there is no inter-racial variation in chromatin frequency. Reasons are given for disregarding nuclear appendages as an accurate indication of 'sex '. Chapter VI Embryological stage s i n the development of the human urogenital tracts are recounted after considering the mechanisms of sex determination. Pathogenesis of intersexuality is considered briefly. Chapter VII Gonadal dysgenesis of the female, including Turner's syndrome and phenotypes of both male and female are presented. The classification, pathology, aetiological and cytogenetic factors are described. Illustrative case reports and extensive discussion of the syndrome are presented. Chapter VIII The Klinefelter syndrome occurs in males with supernumerary X chromosomes; a number of chromatin negative, hypogonadal conditions mimic the syndrome: they are described, with notes on the classification, pathology, aetiology and the cytogenetic features. A series of case reports demonstrate both chromatin positive and negative types. Special reference is made to the dermatoglyphic profiles which were discovered to differentiate the XY males into two groups. Chapter IX Three syndromes, the XXX, XYY and agonadism, were not encountered in this study and are consequently not discussed. Chapter X The adrenogenital syndrome has several distinctive signs which are mimicked by induced virilization; these are described and a number of case reports are presented to illustrate the syndromes. Chapter XI Male intersexes occur in several different forms: the classification of the group is explained and a distinction is made between intersexes and those with simple, or 'pseudo-intersexual', defects. The signs of the different syndromes are detailed, together with data concerning the aetiology and cytogenetics. A series of patients' case histories is used to illustrate the various syndromes. Chapter XII Idiopathic female intersexuality is defined and a short explanation of the classification is given. The signs found in this syndrome are detailed and a single case report, which is of exceptional interest because of severe masculinization and the formation of a phallic urethra, is presented. Chapter XIII Hermaphroditism is defined and the subgroups are explained. The variability of signs is discussed and details of anatomy and histology of the genital tract are given . A single hermaphrodite was encountered during the survey and the case is described. Three other patients, all infants, were suspected of being hermaphroditic but because gonadal biopsy was not undertaken they were discharged from hospital without a diagnosis having been made. Discussion of the aetiological mechanisms is presented and the need for early diagnosis and treatment is emphasized. Chapter XIV Some of the simple genital anomalies and somatic defects which resemble intersex are mentioned and are illustrated by attenuated case reports. Chapter XV The incidence of those intersexual conditions recognizable at birth by anatomical deformity is calculated from a total population of 21,000 live births recorded during the calendar year, 1969. The incidence was very low (1:7000) and does not permit analysis of inter-racial distribution. Prevalence is calculated from the number of new patients seen by the author during 1969 in Durban. Some interesting observations were made but the primary objective, to determine whether or not intersexuality is more prevalent in the Bantu than any other race, could not be answered with certainty because of the small number of patients. Hermaphroditism was shown not to be the most common type of intersex syndrome in the Bantu. Chapter XVI An outline is given of the normal dermatoglyphic features of the finger prints and palms. Some references of the patterns in Turner's and Klinefelter's syndromes are available from the literature and are compared with the profiles of patients from this series. A distinct dimorphism was found in chromatin negative hypogonadal males and was thought to distinguish between those with congenital or acquired pathology. Normal values for South Africans have not been established satisfactorily and the urgent need for this information is stressed. Chapter XVII A general discussion of the highlights of this study of the epidemiology, clinical presentation and cytogenetics of intersexuality is given and a number of conclusions are drawn .Item Dispersion in slowly moving fluids.(1970) Te Riele, Wolter A. M.; Woodburn, Edward T.; King, R. P.This work is concerned with the characterization of slowly moving fluids and was carried out on the flow of water through a narrow sedimentation tank. Dispersion in the type of flow structure involved is caused mainly by the presence of large eddies and, due to the fact that shear stresses are small, these eddies persist for a considerable period of time. Two flow models are presented : The first model assumes the X- Y- velocity component pair to form a discrete state Markov process in time and dispersion equations for the mean concentration at a point, the variance as well as concentration cross correlations are generated. In the second model the velocity fluctuation components are assumed to be independent, time-stationary Markov processes with normal probability density functions. The stochastic differential equation describing dispersion of tracer is formulated with and without the effect of molecular diffusion and solutions to both cases are presented. Comparison of the model with experimental data obtained from tracer and anemometer measurements show that the model is capable of describing mean dispersion in a relatively small region of the tank and that the tracer experiments were insensitive to molecular diffusion.Item Potassium studies on an Avalon medium sandy loam.(1970) Farina, Martin Patrick Warner.; Hulme, Sampie A.; Sumner, Malcolm E.Abstract available in pdf file.Item Soil acidity and liming in Natal.(1970) Reeve, Neville George.; Sumner, Malcolm E.; Orchard, Edwin Retief.1. Effects of Aluminium Toxicity and Phosphorus Fixation on Crop Growth on Oxisols in Natal Simple, routine methods for estimating exchangeable Al and P fixing capacity of acid soils are described. A glass-house study on eight Oxisols revealed marked growth response of 'trudan' (Sorghum sudanense) to amelioration by lime, gypsum and Ca silicate which is ascribed to elimination of A1 toxicity rather than to improved P availability. Growth response to amelia rants took place up to the point of elimination of exchangeable Al after which a significant reduction in yield occurred. P fixation is shown to be a major fertility limitation in the soils studied. Since no apparent relationship between P fixing capacity and exchangeable A1 existed and since lime did not decrease P fixation despite its ability to eliminate soluble A1, it is concluded that P fixation is an adsorption reaction rather than a precipitation reaction. Although the soils studied are all capable of fixing large quantities of P considerable variation exists between them. Fertilizer recommendations based only on an estimate of the available P in the soil per se could thus be in serious error. 2. Lime Requirements of Natal Oxisols based on Exchangeable Aluminium The exchangeable Al status of eight Natal Oxisols is a suitable criterion for the measurement of lime requirement defined as the amount of lime necessary for maximum crop production. The principal function of lime in these soils is to eliminate A1 toxicity; it has little or no effect on P availability. A "critical value" for exchangeable A1 below which 'trudan' did not respond to lime application was found. On the average the amount of lime necessary for maximum growth and exchangeable Al control was approximately one sixth the amount required to raise the soil pH to 6.5. 3. Cation Exchange Capacity and Exchangeable Aluminium in Natal Oxisols Positive charges in acid soils reduce CEC at low electrolyte concentration probably by double layer interaction. The resultant net CEC (determined by washing soil free of salt with water) is the effective CEC under field conditions and the difference between net CEC and exchangeable bases is accordingly a convenient measure of exchangeable A1. A reaction scheme is proposed which relates the large pool of non-exchangeable Al (extractable with N NH[4]0Ac-pH4) in these soils to the relatively small amounts of exchangeable AI; this reaction scheme is governed primarily by net CEC and exchangeable bases rather than by pH. 4. Amelioration of Subsoil Acidity in Natal Oxisols, The large pH dependent CEC in Natal Oxisols effectively limits the downward movement of lime. Although heavy fertilisation, particularly with acid forming nitrogenous fertilizers increases the rate of movement, relatively small amounts of Ca salts having little ability to neutralise subsoil exchangeable Al could be leached from limed topsoil. In contrast, bases equivalent to 80% of that applied leached rapidly from gypsum treated topsoil. Although gypsum did not eliminate subsoil exchangeable A1, it was considerably more efficient than lime in this respect. However, gypsum caused severe loss of exchangeable Mg which could have serious nutritional consequences if not corrected.Item An economic analysis of the demand for resources and the supply of output in South African agriculture.(1970) Nieuwoudt, Wilhelmus Liberté.; Behrmann, Herbert Ian.No abstract available.Item Local atmospheric circulations and the mesoclimate of Durban.(1970) Preston-Whyte, Robert Arthur.; Davies, Ronald John.Rapid urban and industrial growth along the Natal coast has occurred with little concern for characteristics of local climate. In general, industrial growth has taken place without taking into account the potential for pollution transportation during the winter season; urban areas have developed without consideration for the vital need in sub-tropical latitudes to maintain adequate mixing of the lower atmosphere. The apparent inadequacy in planning for climate has partly been due to a lack of understanding of the nature and characteristics of local wind systems. The motivation for this study stems , therefore, from the need to evaluate the influence of land-sea and topographically-induced wind systems upon certain aspects of weather and climate on the Natal coast. During summer, moist and relatively cool air is advected almost daily over the Natal coast by the sea breeze . Observations of spatial and temporal variations of these winds were made in the period 1963-69 from recording stations in the Durban area and along a 40-mile transect approximately normal to the coast at Durban. Comparable observations have not as yet been made in South Africa nor have there been a ttempts to examine the influence of sea breezes upon selected climate and weather phenomenon. In this latter connection the role of the sea br eeze is examined in two separate fields in this study, namely urban climatology and thunderstorm development. Climatic discomfort caused by the combined effect of high temperatures and humidities on the Natal coast, is at a maximum in urban areas . Since these areas are also highly populated , a need exists to evaluate the ability of the sea breeze to reduce urban temperatures by advection of cooler air over the area, by eddy diffusion of heat or by displacement of urban temperatures aw~ from poorly ventilated areas. Thus climatic discomfort in these areas may also be reduced. Detailed observations of the influence of the sea breeze, in particular, and wind in general, upon the spatial variation of temperature , humidity and human comfort were, therefore, undertaken in the Durban area. It is believed that this i s the first time an attempt has been made to describe the spatial distribution of a comfort index in an urban area. The results should be of interest to the a rchitect and town planner. The sea breeze, strengthened by gradient and valley Vlinds, is shown to penetrate at least 40 miles inland. In accordance with this , it is suggested that the inland invasion of marine air takes place in response to lowered pressure in adjacent inland areas in southern Natal and provides the moisture required to feed thunderstorms which develop in this area. These storms subsequently move towards the coast following the retreating convergence zone between winds with an onshore and offshore component of motion and reach Durban after sunset. Land breezes are best developed in winter. Observational techniques were similar to those employed in the sea breeze study and provide the only detailed examination of spatial and temporal variations of land breezes in South Africa. Until recently the nature and characteristics of topographically-induced winds in Natal were also a relatively unexplored feature of local atmospheric circulations. However, Tyson (1967) has examined local winds in certain Natal valleys and his prediction that mountain- plain winds reach the coast during the night is also examined in this study. While the relatively weak. and shallow land breeze may be of secondary importance when compared with the sea breeze, it would be a mistake to underestimate the importance of these winds upon certain aspects of coastal climate. In p~rticular the tendency for land breezes to initiate cloud and precipitation at night is examined while the potential for the transportation of atmospheric pollution by these winds is also briefly discussed. A study of the diurnal variation of precipitation at Durban reveals a high frequency of low intensi~ precipitation at night. The nature of this precipitation differs in both frequency and" amount from high intensity rainfall which is the product of thunderstorm and frontal activity. It is suggested in this study that the land breeze plays a dominant role in providing the buoyancy necessary to cause nocturnal drizzle precipitation from shallow stratus cloud. The thesis is divided into four parts. Part I examines details of the physiography, weather, climate, observati ~nal methods and analysis techniques. Because of the variability of weather on the coast of Natal that section is dealt with in more detail than would have been deemed necessary for a similar study inland. Without knowledge of the characteristics of the atmospheric circulation, the behaviour of local wind systems in relation to large scale systems could not be adequately discussed. In Part II land and sea breezes and topographically-induced wind systems are examined in detail. Emphasis is placed not only on the observational characteristics of these winds such as onset, depth, velocity gradient, surging, relation to gradient winds and dissipation but also on their relation to theoretical models of the relevant wind system. The influence of local wind systems upon selected climatic elements is dealt with in Part Ill. Characteristics of the diurnal variation of precipitation are examined in Chapter 6. Rainfall frequencies and amounts are shown to be highest in the first half of the night and a model is developed to explain the influence of land breezes and mountain-plain winds upon low intensity but high frequency nocturnal rainfall. High intensity but low frequency rainfall produced by thunderstorms also occurs soon after sunset and a further model is advanced to explain this phenomenon in relation to the sea breeze. The effect of air movement upon the spatial variation of temperature, humidity and a discomfort index in both summer and winter is examined in Chapters 7 and 8. The relationship between these elements has permitted the development of an empirical model to predict values across the city of mean midday summer and winter temperatures as well as discomfort index values. In Part IV the most significant aspeots relating to the study as a whole are summarised. In conclusion the potential f or the transport of pollutants by land breezes and topographically induced winds is briefly discussed as an aid to planning and siaple spatial models are given showing generalised air movement and ventilation characteristics in the Durban area and along the Natal coast.Item The mineralogy and related geology of the Albert Silver Mine, Bronkhorstspruit, Transvaal(1970) Champion, Alfred Timothy.The Albert Silver mine is situated on the farm Roodepoortjie, 32 kilometres north of Brorikhorstspruit in the Transvaal. The deposit forms the largest of a number of sub-parallel quartzhematite lodes accompanied by sulphide mineralization and is accompanied by an extensive alteration zone along its northern flank.