Member perspectives on the role of social capital in the success of the Heiveld Cooperative in the Northern Cape, South Africa
- Authors: Carlisle, Juliet Hazel
- Date: 2014
- Subjects: Heiveld Cooperative , Human capital -- South Africa , Social capital (Sociology) -- Economic aspects -- South Africa , Agriculture, Cooperative -- South Africa , Cooperative marketing of farm produce -- South Africa , Rooibos tea industry -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:825 , http://hdl.handle.net/10962/d1011734 , Heiveld Cooperative , Human capital -- South Africa , Social capital (Sociology) -- Economic aspects -- South Africa , Agriculture, Cooperative -- South Africa , Cooperative marketing of farm produce -- South Africa , Rooibos tea industry -- South Africa
- Description: The aim of this qualitative study is to explore the perspectives of current members of the cooperative regarding the role of social capital in the success of the Heiveld Cooperative on the Suid Bokkeveld in the Northern Cape, South Africa (SA). This cooperative has been cited by several researchers as being successful for various reasons, including the existence of a marketable resource, a steady increase in production, and certification through Fairtrade, resulting in an export market. Social capital, as a contributing factor to the success of the cooperative, has not however previously been investigated in depth. In light of the unique success of this cooperative, it is important to obtain an in-depth understanding of the role of social capital, if any, in its success, particularly in the formation and day-to-day operation of the cooperative. With a particular focus on the members’ perspectives of the cooperative, this qualitative research adopted a case study approach to explore and to gain multiple and subjective understanding of the role played by social capital in the success of the Heiveld Cooperative. This may assist the organisation under study, as well as similar initiatives, in strategically harnessing the benefits of social capital as a resource in future. This report has three interrelated sections. The first part is an academic paper, which includes a condensed literature review, research methods, results and discussions. The second part is an expanded literature review, while the third section details the research methods. It is vital to note that these sections are separate, but interrelated. Convenience sampling was used to identify current members of the cooperative who participated in this exploratory qualitative study. Four heterogeneous focus group discussions, with a total of 44 members of the Heiveld Cooperative in the Suid Bokkeveld, were conducted. The focus groups were heterogeneous, as they included ordinary members, founding members and committee members. A guideline with questions based on the theory of social capital was developed, and used to initiate or stimulate discussion among the members of the cooperative in order to address the key research question, namely: What was the role of social capital, if any, in the success of the Heiveld Cooperative in the Northern Cape as perceived by current cooperative members? The primary source of data was collected through focus group discussions, while secondary data was obtained from documents in a form of internal reports and papers written for the Heiveld Cooperative. Data was analysed using open coding and constant comparison techniques in order to induce emerging themes from the data. Findings of this study revealed that social capital played a major and influential role during the inception and also in the successful operation of the Heiveld Cooperative, by bonding and bridging not just between individual members, but also between communities, trading partners and other collaborators. Another key finding of this study is that social capital was also critical in enhancing supportive knowledge sharing, and the promotion of pride and shared identity, which the study identifies as aspects of cognitive social capital. Interestingly, the cognitive dimension of social capital in the Heiveld Cooperative has contributed to the weakening of social capital, as evident in claims related to lack of transparency and procedural injustice. Last, but not least, leveraging the sense of community has also been useful in promoting collective efficacy, strengthening familial togetherness, and enhanced democratisation of decision-making. Diminished trust, based on perceived oligarchy and nepotism is gradually weakening relational social capital. Findings in this study are illuminated using the social capital theory described by Nahapiet and Ghoshal (1998) to depict the social, cognitive and relational aspect of social capital that are at work at Heiveld Cooperative. Additionally, the social network theory by Hoppe and Reinelt (2010) is used to highlight the systemic view of social capital, which embraces the structural, relational and cognitive nature not only internal to but also between networks of the cooperative. Recommendations are provided to ensure social capital is harnessed, rather than undermined. These include the need to promote the processes of learning, monitoring and discussion that have been implemented; harnessing the benefits of bonding and bridging social capital; leveraging the sense of community and applying a more systemic view of social capital; and addressing perverse aspects of social capital such as nepotism and oligarchy that have been identified.
- Full Text:
- Date Issued: 2014
The life history and fishery assessment of largespot pompano, Trachinotus botla, in northern KwaZulu-Natal, South Africa
- Authors: Parker, Denham
- Date: 2012
- Subjects: Trachinotus -- South Africa -- KwaZulu-Natal , Carangidae -- South Africa -- KwaZulu-Natal , Fishing -- South Africa -- KwaZulu-Natal , Fishery management -- South Africa -- KwaZulu-Natal , Fishing -- Economic aspects -- South Africa -- KwaZulu-Natal , Fish stock assessment -- South Africa -- KwaZulu-Natal , Trachinotus -- Growth -- South Africa -- KwaZulu-Natal , Trachinotus -- Breeding -- South Africa -- KwaZulu-Natal , Trachinotus -- Food -- South Africa -- KwaZulu-Natal , Host-parasite relationships -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5296 , http://hdl.handle.net/10962/d1005141 , Trachinotus -- South Africa -- KwaZulu-Natal , Carangidae -- South Africa -- KwaZulu-Natal , Fishing -- South Africa -- KwaZulu-Natal , Fishery management -- South Africa -- KwaZulu-Natal , Fishing -- Economic aspects -- South Africa -- KwaZulu-Natal , Fish stock assessment -- South Africa -- KwaZulu-Natal , Trachinotus -- Growth -- South Africa -- KwaZulu-Natal , Trachinotus -- Breeding -- South Africa -- KwaZulu-Natal , Trachinotus -- Food -- South Africa -- KwaZulu-Natal , Host-parasite relationships -- South Africa -- KwaZulu-Natal
- Description: Largespot pompano, Trachinotus botla, is a surf zone carangid with a cosmopolitan distribution in subtropical and tropical waters. Within South Africa, the species occurs along the KwaZulu-Natal coastline where it is a popular recreational fishing target. Recreational fishing in southern Africa has developed significantly in recent years, and is now regarded as an industry with huge economic potential. The long-term contribution of South African recreational fisheries to local economies is reliant upon sustainable exploitation through effective management. Trachinotus botla was found to grow rapidly with maximum observed age of six years. Otolith growth zone deposition was validated using edge analysis. Growth was similar between males and females until ~350 mm FL after which females continued to grow while growth in males slowed. The resulting overall sex ratio was slightly female-biased (1 male: 1.3 females). Trachinotus botla matures early with all fish considered to be mature at 290 mm FL, which corresponds to an age of three years. A protracted spawning season was observed ranging from November to February and there was evidence to suggest that T. botla is a serial spawner. Dietary analysis indicates that T. botla is an opportunistic predator with a catholic diet. The opportunistic utilization of “superabundant” prey items is a fundamental characteristic of the species feeding habits. An ontogenetic dietary shift was observed at approximately 300 mm FL that was linked to a shift in habitat preference. This thesis provided the first evidence that infection by the tongue-replacing isopod, Cymothoa borbonica, reduces the growth rate of wild host fish populations despite not affecting the diet, feeding habits and feeding frequency of their hosts. These results also highlighted the inadequacy of condition factor as a proxy for quantifying the effects of cymothoids on their hosts, and identified the need to incorporate host age when assessing the effects of parasite infection. Information on the life-cycle of C. borbonica, including estimates of the hypothesized “infectious” period and its longevity were obtained through analysis of parasite infection patterns as a function of host age and length. An assessment of the T. botla shore fishery of KwaZulu-Natal using historical catch data revealed that the fishery is stable. Productivity of the T. botla fishery increased towards the north of KwaZulu-Natal. Distinct seasonal variations in the T. botla fishery were also noted with catches peaking in summer months and lowest during winter. A per-recruit assessment revealed that the species is currently underexploited (SBR = 62% of pristine levels), and fishing mortality rate could be doubled before reaching the spawner biomass-per recruit target reference point of FSB₄₀. A combination of the life history characteristics of species, the nature of the recreational shore fishery together with the current management regulation of 5 fish person⁻¹ day⁻¹ has ensured the sustainable utilization of the T. botla resource in KwaZulu-Natal.
- Full Text:
- Date Issued: 2012
Quantifying crop damage by Grey crowned crane balearica regulorum regulorum and evaluating changes in crane distribution in the North Eastern Cape, South Africa
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
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- Date Issued: 2011
Application of multiserver queueing to call centres
- Authors: Majakwara, Jacob
- Date: 2010
- Subjects: Call centers , ERLANG (Computer program language) , Queuing theory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5578 , http://hdl.handle.net/10962/d1015461
- Description: The simplest and most widely used queueing model in call centres is the M/M/k system, sometimes referred to as Erlang-C. For many applications the model is an over-simplification. Erlang-C model ignores among other things busy signals, customer impatience and services that span multiple visits. Although the Erlang-C formula is easily implemented, it is not easy to obtain insight from its answers (for example, to find an approximate answer to questions such as "how many additional agents do I need if the arrival rate doubles?"). An approximation of the Erlang-C formula that gives structural insight into this type of question would be of use to better understand economies of scale in call centre operations. Erlang-C based predictions can also turn out highly inaccurate because of violations of underlying assumptions and these violations are not straightforward to model. For example, non-exponential service times lead one to the M/G/k queue which, in stark contrast to the M/M/k system, is difficult to analyse. This thesis deals mainly with the general M/GI/k model with abandonment. The arrival process conforms to a Poisson process, service durations are independent and identically distributed with a general distribution, there are k servers, and independent and identically distributed customer abandoning times with a general distribution. This thesis will endeavour to analyse call centres using M/GI/k model with abandonment and the data to be used will be simulated using EZSIM-software. The paper by Brown et al. [3] entitled "Statistical Analysis of a Telephone Call Centre: A Queueing-Science Perspective," will be the basis upon which this thesis is built.
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- Date Issued: 2010
A study of fuzzy sets and systems with applications to group theory and decision making
- Authors: Gideon, Frednard
- Date: 2006
- Subjects: Fuzzy sets , Fuzzy systems , Abelian groups , Decision making
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5417 , http://hdl.handle.net/10962/d1005231 , Fuzzy sets , Fuzzy systems , Abelian groups , Decision making
- Description: In this study we apply the knowledge of fuzzy sets to group structures and also to decision-making implications. We study fuzzy subgroups of finite abelian groups. We set G = Z[subscript p[superscript n]] + Z[subscript q[superscript m]]. The classification of fuzzy subgroups of G using equivalence classes is introduced. First, we present equivalence relations on fuzzy subsets of X, and then extend it to the study of equivalence relations of fuzzy subgroups of a group G. This is then followed by the notion of flags and keychains projected as tools for enumerating fuzzy subgroups of G. In addition to this, we use linear ordering of the lattice of subgroups to characterize the maximal chains of G. Then we narrow the gap between group theory and decision-making using relations. Finally, a theory of the decision-making process in a fuzzy environment leads to a fuzzy version of capital budgeting. We define the goal, constraints and decision and show how they conflict with each other using membership function implications. We establish sets of intervals for projecting decision boundaries in general. We use the knowledge of triangular fuzzy numbers which are restricted field of fuzzy logic to evaluate investment projections.
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- Date Issued: 2006
Biochemical characterization of plasmodium falciparum heat shock protein 70
- Authors: Matambo, Tonderayi Sylvester
- Date: 2004
- Subjects: Plasmodium falciparum , Malaria -- Prevention , Protein folding , Proteins -- Purification , Heat shock proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4134 , http://hdl.handle.net/10962/d1015767
- Description: Plamodium falciparum heat shock protein (PfHsp70) is believed to be involved in the cytoprotection of the malaria parasite through its action as a molecular chaperone. Bioinformatic analysis reveal that PfHsp70 consists of the three canonical Hsp70 domains; an ATPase domain of 45 kDa, Substrate binding domain of 15 kDa and a C-terminal domain of 10 kDa. At the C-terminus there is a GGMP repeat motif that is commonly found in Hsp70s of parasitic origins. Plasmodium falciparum genome is 80% A-T rich, making it difficult to recombinantly express its proteins in Escherhia coli (E. coli) as a result of rare codon usage. In this study we carried out experiments to improve expression in E. coli by inserting the PfHsp70 coding region into the pQE30 expression vector. However multiple bands were detected by Western analysis, probably due to the presence of rare codons. The RIG plasmid, which encodes tRNAs for rare codons in particular Arg (AGA/AGG), Ile (AUA) and Gly (GGA) was engineered into the E. coli strain resulting in production of full length PfHsp70. Purification was achieved through Ni²⁺ Chelating sepharose under denaturing conditions. PfHsp70 was found to have a very low basal ATPase activity of 0.262 ± 0.05 nmoles/min/mg of protein. In the presence of reduced and carboxymethylated lactalbumin (RCMLA) a 11-fold increase in ATPase activity was noted whereas in the presence of both RCMLA and Trypanosoma cruzi DnaJ (Tcj2) a 16-fold was achieved. For ATP hydrolysis kcat value of 0.003 min⁻¹ was obtained whereas for ADP release a greater kcat value of 0.8 min⁻¹ was obtained. These results indicated that rate of ATP hydrolysis maybe the rate-determining step in the ATPase cycle of PfHsp70.
- Full Text:
- Date Issued: 2004
Case studies of equivalent fuzzy subgroups of finite abelian groups
- Authors: Ngcibi, Sakhile L
- Date: 2002
- Subjects: Abelian groups , Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5401 , http://hdl.handle.net/10962/d1005215 , Abelian groups , Fuzzy sets
- Description: The broad goal is to classify all fuzzy subgroups of a given type of finite group. P.S. Das introduced the ntion of level subgroups to characterize fuzzy subgroups of finite grouops. The notion of equivalence of fuzzy subgroups which is used in this thesis was first introduced by Murali and Makamba. We use this equivalence to charterise fuzzy subgroups of inite Abelian groups (p-groups in particular) for a specified prime p. We characterize some crisp subgroups of p-groups and investigate some cases on equi valent fuzzy subgroups.
- Full Text:
- Date Issued: 2002
Aspects of nutrition of the swordtail fish, Xiphophorus Helleri, (Family : Poeciliidae) under intensive culture conditions
- Authors: Kruger, David Philip
- Date: 1996
- Subjects: Xiphophorus helleri -- Nutrition , Fish culture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5219 , http://hdl.handle.net/10962/d1005062 , Xiphophorus helleri -- Nutrition , Fish culture
- Description: The aim of this work was to investigate the nutrition of a popular ornamental fish, the swordtail (Xiphophorus helleri), under intensive aquaculture conditions. The study focused on the formulation and manufacture of artificial dry diets, as well as the influence of livefeed supplementation on growth and nutritional indices of both juvenile and broodstock fish. A combination of 65% fishmeal and 35% soya oil cake meal was found to closely approximate the essential amino acid profile of X helleri (r² = 94,3%) and lysine was identified as the first limiting amino acid. The influence of dietary protein and energy on the growth of X helleri was investigated by means of a growth trial comparing a range of nine test diets combining 3 crude protein (45,38 and 30%) and 3 digestible energy (16,5, 14,5 and 12,5 kJ/gram) levels. A high crude protein content (45% dry matter) and a protein to energy ratio of ≥ 27 mg protein per kJ digestible energy was shown to promote optimal growth rate and feed conversion ratio in juvenile X helleri. The final body protein and lipid content of the fish were significantly correlated with the dietary protein to energy ratio. The nutritional value of identical dietary formulations prepared by drum-drying or cold extrusion techniques and presented either as flake or crumble particles was evaluated in a growth trial and through analysis of vitamin C levels in the diets. Up to 27% of vitamin C activity was destroyed during the drum-drying of flake diets, while 80% of the remaining vitamin C was lost through leaching within 10 minutes of immersion in water. A crumble-type diet was shown to be acceptable to X helleri, and yielded significantly better growth rate and feed conversion than the equivalent flake feed. Almost 19% of fish fed the flake diets developed vitamin C deficiency symptoms including scoliosis and lordosis, while this was completely prevented by feeding crumbles, indicating a significant restriction of leaching losses from this type of particle. The use of livefeed (Daphnia spp.) as a daily supplement to dry feeds was shown to result in a significant improvement in growth rate and survival of juvenile swordtail fish. Furthermore, the synergistic action of nutrients contained in the livefeed resulted in an improvement in the feed conversion efficiency of the artificial formulation. While mortalities of 13,4% and 15% were recorded in fish fed exclusively on flake feed or Daphnia, no mortality occurred in the group fed the supplemented diet. Furthermore, the incidence of vitamin C deficiency symptoms was prevented by daily supplementation with Daphnia. Fish fed exclusively on Daphnia exhibited significantly more intense pigmentation due to carotenoids contained in the livefeed. In broodstock fish maintained primarily on flake diets, growth rate, feed conversion ratio as well as reproductive performance, as measured by fecundity, were significantly improved by daily livefeed supplementation. Weekly supplementation showed no measurable advantage over flake feed only. A direct correlation was demonstrated between fecundity and size of female fish with a mean fecundity of 190 embryos per female in those fed a daily Daphnia supplement. This was significantly higher than the yield from the non-supplemented or weekly supplemented treatments (133 and 140 embryos per female respectively). Despite these differences, the number of young harvested during the experiment did not differ between treatments and this discrepancy was ascribed to parental cannibalism of newborn juveniles. This phenomenon constitutes a major potential bottleneck in production with estimates of up to seventy percent of young lost in some exp experimental tanks. In conclusion, the present study demonstrated that established aquaculture nutrition principles and techniques are applicable to the tropical ornamental fish species, X helleri. It was demonstrated that by using balanced crumble feed formulations, and regular livefeed supplementation, production yields under intensive conditions may be significantly improved. Suggestions for future work on poeciliid production in South Africa include investigation of the economic implications of the recommendations stemming from this project, and further research into effective restriction of parental cannibalism of newborn fish.
- Full Text:
- Date Issued: 1996
Determination of distinctness among citrus cultivars using biochemical and molecular markers
- Authors: Carstens, Karin
- Date: 1995
- Subjects: Citrus fruits -- South Africa , Citrus fruits -- Research -- South Africa , Citrus fruits -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4022 , http://hdl.handle.net/10962/d1004082 , Citrus fruits -- South Africa , Citrus fruits -- Research -- South Africa , Citrus fruits -- Analysis
- Description: Citrus is among the most important fruit crops worlstwide, and therefore the preservation and improvement of citrus germplasm is of the essence. Citrus breeders are often faced with the difficulty of distinguishing between new and existing cultivars because of the ambiguous nature of morphological traits due to environmental influences and error in human judgement. The protection of new varieties is very important to the breeder. New varieties cannot be patented in South Africa, but it can be protected by Plant Breeders' Rights, only if it is genetically distinguishable and significantly different economically from existing varieties. Cultivars in four genera (c. sinensis, C. paradisi, C. grandis and C. reticulata) included in the Citrus Improvement Programme (CIP) or cultivars awaiting recognition of Plant Breeders' Rights by the International Union for the Protection of New Plant Varieties (UPOV) were analyzed with Isoenzymes, Restriction Fragment Length Polymorphism (RFLP) and Random Amplified Polymorphic DNA (RAPD). Five enzyme systems (PGM, PGI, MDH, GOT and IDH) were analyzed and founded to be suitable for grouping together cultivars belonging to the same genera. It was not suited for routine discrimination of cultivars in a particular genus. RFLP studies were conducted on five grapefruit cultivars, using cDNA clones from a genomic library of Rough Lemon. RFLP studies were valuable for the discrimination of closely related cultivars which probably originated from a common ancestor by bud mutations. This technique was, however, abandoned due to its biohazardous nature and replaced by the PeR-based Random Amplified Polymorphic DNA. RAPDs are easy to perform and gave promisin& results which were exploited to reveal polymorphisms between cultivars within the various groups. Although the interpretation of data produced by this method is often suspicious, it is the best method currently available for cultivar identification. It can playa complementary role in the protection of new varieties when classical morphological interpretation of differences is not capable of determining sufficient distinctness for the awarding of Plant Breeders' Rights.
- Full Text:
- Date Issued: 1995
Geochemical exploration in calcrete terrains
- Authors: Krug, Mark Alan
- Date: 1995 , 2013-10-02
- Subjects: Duricrusts , Silcrete , Geochemical prospecting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5026 , http://hdl.handle.net/10962/d1006891 , Duricrusts , Silcrete , Geochemical prospecting
- Description: This work takes a look at some of the literature on calcretes and especially the problem of geochemical exploration in calcrete terrains. The conclusion that will be reached is that exploration in calcrete terrains is not futile and that provided the explorationist is aware of the types of calcrete and their genetic implications calcrete can be used as a sampling medium and anomalies can be detected through calcrete (p.1.) , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 1995
An investigation of isolated bursts of solar radio noise
- Authors: Shuter, William Leslie Hazlewood
- Date: 1958
- Subjects: Solar physics -- Research , Solar radio emission
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5539 , http://hdl.handle.net/10962/d1013216
- Description: The literature on isolated bursts and possible mechanisms of origin has been critically reviewed, and observations point to a mechanism involving omission of electromagnetc radiation from plasma oscillations in the solar corona excited by outward travelling disturbances. Solar noise observations on 125 Mc./s. recorded at Rhodes University during the period November 26 1957 - February 6 1958 have been analysed by the author for isolated bursts, and these observations show the same general features reported by previous investigators. In interpretation of these records particular attention has been devoted to two aspects of isolated bursts; namely the preponderance on single frequency records of double-humped bursts, and the shape of isolated burst profiles. The authors suggests that a probable explanation of double-humped bursts observed on any frequency f is that the first hump represents omission at or near the level of zero refractive index for f radiation, and that the second hump corresponds to harmonic omission at the f/2 level. Source velocities may be calculated from the time delay between the peaks and an average value of 2 x 10⁴ km./sec. was obtained from an analysis of 21 double-humped bursts. This value is in very good agreement with that deduced by Wild (1950b) from the rate of frequency drift of peak intensity of isolated bursts. Simple isolated bursts had decay profiles which are approximatley exponential in shape, and this is usually interpreted in terms of the natural decay of plasma oscillations in the medium of origin. The author has verified that the exponential function is a good fit to the observed decay profiles, but shows that a relation of the form I - ¹/n (superscript) ⋉ t (where I is intensity and t is time) fits just as well. An alternative model is suggested which would lead to an exponential-like decay profile which is not determined by the natural decay of plasma oscillations. The work concludes with some suggestions for further research.
- Full Text:
- Date Issued: 1958
A study of the errors involved in the sampling of soils
- Authors: Steyn, Willem Johannes Abraham
- Date: 1945
- Subjects: Soils -- Analysis , Soil chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4505 , http://hdl.handle.net/10962/d1013290
- Description: The importnnce of representative soil sampling is now beginning to receive more general recognition. The analysis of the sample, and any chemical or physical treatment it may undergo in the laboratory, is of little practical value if it is not known with reasonable certainty that this sample represents fairly the area from which it as taken. It has been said over and over again, that the existence of the world's whole civilization is dependent upon a mere strip of soil, only 9 inches in depth. The study of the soil is therefore of special importance if only for the practical end of replacing any nutrient deficiencies which may be found. Intro., p. 1.
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- Date Issued: 1945