The aim of the research presented in this dissertation was to further the implementation of push-pull for control of Eldana saccharina on sugarcane in the Midlands North region, KwaZulu-Natal, South Africa. Eldana saccharina, an indigenous stem borer, is the most damaging pest of sugarcane in South Africa, and sustainable control has still not been achieved. The push-pull strategy, a form of habitat management, has been developed for E. saccharina and is recommended as part of an integrated pest management (IPM) approach. Implementation of this strategy for both large- and small-scale farmers was facilitated through mixed methods social research. It included a novel exploratory network analysis to understand the process of technology adoption by farmers. Surveys showed that large-scale farmers have a good knowledge of E. saccharina, IPM and push-pull but that they needed more practical knowledge for implementation of the strategy. Farmers recommended experiential learning opportunities such as field days and model farms to get to know more about this technology. Despite demonstrating a positive attitude towards push-pull, farmers perceived it to be a ‘hassle’ and this is potentially the biggest barrier to its adoption. However, with suitable learning opportunities for farmers and good support for planting inputs, implementation of push-pull is likely to succeed. Sugarcane was shown to play an important role in the livelihoods and farming systems of small-scale growers. They did not perceive E. saccharina as a serious production constraint and had poor knowledge of the pest and its control. Extension for small-scale growers in this region should focus primarily on weed management and on reducing input costs, but still raising awareness of the increasing threat of E. saccharina. On-farm push-pull field trials showed a significant reduction of E. saccharina damage on two farms. Mean percentage damaged internodes decreased from 4.1% to 2.7% and from 1.7% to 1.1% in the presence of the repellent grass species, Melinis minutiflora. Where farmers did not manage their crops well, push-pull was not effective. It is therefore crucial that push-pull within an IPM framework be implemented together with good crop management practices. Stem borer surveys in wetlands on sugarcane farms revealed a high diversity of indigenous stem borers and parasitoids, including a stem borer species, Pirateolea piscator, which may pose a threat to crops in the future. These findings, together with a literature review on the significance of on-farm biodiversity and ecosystem services, demonstrated the value which wetlands have for pest management on sugarcane farms. Wetland health assessments were used to develop a tool for farmers to assess and utilise the wetlands on their farms for improved management of E. saccharina. This study highlights the importance of a farmer-participatory approach to implementation of knowledge-intensive farming practices such as push-pull. The importance of wetlands for providing pest regulatory services on sugarcane farms has shown that environmental sustainability needs to become a fundamental principle of farming and agricultural research. Participatory implementation of push-pull, as recommended in this dissertation, could act as a driving force for agroecology in the South African sugar industry and move sustainable farming practices off the pages of journals and manuals onto farmers’ fields. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2013

The aim of the research presented in this dissertation was to further the implementation of push-pull for control of Eldana saccharina on sugarcane in the Midlands North region, KwaZulu-Natal, South Africa. Eldana saccharina, an indigenous stem borer, is the most damaging pest of sugarcane in South Africa, and sustainable control has still not been achieved. The push-pull strategy, a form of habitat management, has been developed for E. saccharina and is recommended as part of an integrated pest management (IPM) approach. Implementation of this strategy for both large- and small-scale farmers was facilitated through mixed methods social research. It included a novel exploratory network analysis to understand the process of technology adoption by farmers. Surveys showed that large-scale farmers have a good knowledge of E. saccharina, IPM and push-pull but that they needed more practical knowledge for implementation of the strategy. Farmers recommended experiential learning opportunities such as field days and model farms to get to know more about this technology. Despite demonstrating a positive attitude towards push-pull, farmers perceived it to be a ‘hassle’ and this is potentially the biggest barrier to its adoption. However, with suitable learning opportunities for farmers and good support for planting inputs, implementation of push-pull is likely to succeed. Sugarcane was shown to play an important role in the livelihoods and farming systems of small-scale growers. They did not perceive E. saccharina as a serious production constraint and had poor knowledge of the pest and its control. Extension for small-scale growers in this region should focus primarily on weed management and on reducing input costs, but still raising awareness of the increasing threat of E. saccharina. On-farm push-pull field trials showed a significant reduction of E. saccharina damage on two farms. Mean percentage damaged internodes decreased from 4.1% to 2.7% and from 1.7% to 1.1% in the presence of the repellent grass species, Melinis minutiflora. Where farmers did not manage their crops well, push-pull was not effective. It is therefore crucial that push-pull within an IPM framework be implemented together with good crop management practices. Stem borer surveys in wetlands on sugarcane farms revealed a high diversity of indigenous stem borers and parasitoids, including a stem borer species, Pirateolea piscator, which may pose a threat to crops in the future. These findings, together with a literature review on the significance of on-farm biodiversity and ecosystem services, demonstrated the value which wetlands have for pest management on sugarcane farms. Wetland health assessments were used to develop a tool for farmers to assess and utilise the wetlands on their farms for improved management of E. saccharina. This study highlights the importance of a farmer-participatory approach to implementation of knowledge-intensive farming practices such as push-pull. The importance of wetlands for providing pest regulatory services on sugarcane farms has shown that environmental sustainability needs to become a fundamental principle of farming and agricultural research. Participatory implementation of push-pull, as recommended in this dissertation, could act as a driving force for agroecology in the South African sugar industry and move sustainable farming practices off the pages of journals and manuals onto farmers’ fields. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2013

Title from first page of PDF document. Includes bibliographical references (p. 154-156).

After the second world war it became common for individuals in economically unstable countries to work migrate towards countries with better work opportunities. Common for this type of migration is that the individual only works for a few years before re-emigrating to their home country. In the town of Olofström in southern Sweden of the migrant workers an overwhelming majority instead chose to permanently settle. By examining the worker migration during the 60- and 70s in Olofström through archive studies and interviews with the individuals involved in the worker migration, this study aims to examine the push-pull-factors that were the basis for the individual's decision to permanently settle instead of re-emigrate. The study shows that it was partially a “lucky” coincidence that the surroundings of Olofström was very similar to the migrant workers home areas, but also that the municipality in Olofström was willing to spend enormous resources to develop their school system for the migrant workers' children played a big role. A well-built school system that gave the Finnish children an opportunity to receive a good education in both the foreign language and their mother tongue proved to be a bigger pull-factor than social acceptance was a push-factor.

Inledning: Sedan Bosmandomen 1995 har antalet afrikanska fotbollsspelare som kommer till Sverige ökat. Skogvang (2008), Scott (2015) och Najarian (2015) berättar att det är ett problem med att minderåriga fotbollsspelare från Afrika luras över till Europa av ohederliga agenter för att de ska få provspela med professionella fotbollsklubbar. Istället för provspel slutar det allt för ofta med att agenter tar fotbollsspelares pengar och lämnar dem i ett främmande land utan pengar eller dokumentation (Skovang, 2008, Scott, 2015, Najarian, 2015). Problemen uppstår när talangerna blir allt yngre och migrerar utan att ha presterat i hemlandet. Syftet med vår studie är att undersöka varför afrikanska fotbollsspelare kommer till Sverige och hur de upplever de olika migrationsfaserna. Metoden var en intervjustudie med semistrukturerade intervjuer, där två avtalslösa professionella afrikanska fotbollsspelare intervjuades. Teorin som användes för att kunna besvara vad det var som motiverade fotbollsspelarna att migrera till Sverige var Lee´s (1966) teori om push- pull. Resultatet: visade att det som ofta får spelarna att lämna Afrika är fattigdom i hemlandet och pengarna är det som motiverar spelarna att migrera och fungerar som en pull-faktor. Fotbollsspelarna upplevde även en problematik i att anpassa sig till det svenska samhället som till exempel hur de betalade räkningar. Studien bidrar till en ökad medvetenhet för klubbarna som bestämmer sig för att värva in unga afrikanska fotbollsspelare och om vilka resurser som behövs för att spelarna ska kunna prestera på toppnivå. De behöver hjälp av antingen en heltidsanställd likt det AIK har eller ett system med värdfamiljer likt det som finns i England.

There are two sections to this research dissertation. Part one includes syntheses of fused-ring heterocycles derived from thiazole, oxazole, benzoxazole and benzothiazole derivatives and trifluoroacetylations of in situ generated N-methyl cyclic ketene-N,O/Sacetals. Attempted functionalized polymer syntheses from plant-derived 5-(hydroxymethyl) furfural are discussed in part two. Three 2-methylthiazoles, 2,4,5-trimethyloxazole, 2-methylbenzoxazole and 2- methyl-benzothiazole were each reacted with benzoyl chloride in acetonitrile/triethylamine to generate benzyl-vinyl esters. Base hydrolysis of these benzyl-vinyl esters formed 2-(heterocyclic)-1-phenylethenols which exist in both ketoenol tautomeric forms. These tautomers were used as starting materials for fused-ring heterocycle syntheses. Each tautomeric pair react with dimethyl acetylenedicarboxylate in methanol giving the 5,6-ringused 8-benzoyl-5-oxo-5H-thiazolo-, 8-benzoyl-5-oxo-5H-oxazolo-, 4-benzoyl-1-oxo-1H-benzo[4,5]oxazolo- and 4-benzoyl-1-oxo-1H-benzo[4,5]thiazolo [3,2-a]pyridinecarboxylate derivatives. Two novel 5,7-ringused 9-benzoyl-2,3- dimethyl-5,6-dihydrothiazolo- and 9-benzoyl-2,3-dimethyl-5,6-dihydrooxazolo[3,2-a] azepine-5,6,7,8-tetracarboxylates formed when the tautomers formed from 2,4,5- trimethyl thiazole and 2,4,5-trimethyl oxazole were reacted with DMADC. These tautomers react with 1,3-diacid chlorides in acetonitrile/triethylamine affording the 5,6-ringused 8-benzoyl-6,6-dialkyl-6H-thiazolo- and 8-benzoyl-6,6- dimethy-6H-oxazolo-, 4-benzoyl-2,2-dimethyl-1H-benzo[4,5]thiazolo- and 4-benzoyl- 2,2-dimethyl-1H-benzo[4,5]oxazolo[3,2,-a]pyridinedione derivatives. Functionalized 5,6- ringused 8-benzoyl-6H-thiazolo- and 8-benzoyl-6H-oxazolo[3,2]pyrimidine-5,7- diones, and 4-benzoyl-1H-benzo[4,5]thiazolo- and 4-benzoyl-1H-benzo[4,5]oxazolo[3,2- c]pyrimidine-1,3(2H)-diones formed reacting the tautomers with N-chlorocarbonyl isocyanate in THF/triethylamine. Significant ring size and substituent effects were observed in trifluoroacetylations of in situ-generated cyclic ketene-N,O/S acetals. In situ-generated 3,4,4-trimethyl-2- methylene-oxazolidine, 3-methyl-2-methylene-oxazolidine and 3-methyl-2-methylene- 1,3-oxazinane each formed β,β-bistrifluoroacetylated products. However, 3-methyl-2- methylene-oxazolidine also afforded a γ-lactam by an iodide-catalyzed rearrangement of its β,β-bistrifluoroacetylated derivative. In situ-generated 3-methyl-2-methylenethiazolidine gave both β-mono- and β,β-bistrifluoroacetylation products. 5-(Hydroxymethyl)furfural synthesized from sucrose was converted to 2,5- bis(hydroxymethyl)furan (2,5-BHMF). 7-Oxanorbornene-type Diels-Alder adducts synthesized from 2,5-BHMF were used as monomers for both ring opening metathesis polymerizations (ROMPs) and polycondensations. ROMP, followed by polycondensation or vise versa were expected to give highly functionalized cross-linked polymers. ROMP of the monomers using three Grubbs’ 1st, 2nd and 3rd generation catalysts were unsuccessful due to the presence of hydroxymethyl groups at one or both bridgeheads that could coordinate Ruthenium. With one bridgehead methyl present ROMP proceeded. Low molecular weight polyesters were synthesized via polycondensation. One was crosslinked using ROMP, but not to its gel point.

ABSTRACT Bridgeless Active Power Factor Correction Using a Current Fed Push Pull Converter Jeramie Seth Bianchi Switched Mode Power Supplies have become increasingly popular for efficient methods of delivering power to an assortment of electronic devices. This thesis proposes a method of using a current fed push pull converter to provide active power factor correction and rectification in a single stage. While most AC-DC converters utilize a bridge rectifier to convert AC-DC and then perform DC-DC conversion, the proposed circuit will utilize its output diodes to perform rectification, thus eliminating the need for a bridge rectifier. This circuit will also inherently provide power factor correction because the input current has a continuous path for current flow due to the current fed topology where no time exists for both switches to be off. Through analog circuitry for the controller, multiple methods of AC main switching are tested, including isolation techniques using optocouplers, to prove the most efficient way to control a bidirectional switch. Simulations with PSPICE and hardware implementation of the design prove that alternative methods to provide quality power conversion for Switched Mode Power Supplies are available. Keywords: Active Power Factor Correction, Current Fed Push Pull Converter, SMPS, Bidirectional Switching, IGBT, Bridgeless Rectification

This project looks at the development and use of a new delivery system for broadcast television news and its relation to the Uses and Gratifications and Push/Pull Theories. An in-home study of interactive news was conducted for two weeks, allowing people access to three local and 5 national newscasts via one interactive newscast. Users were able to access the interactive newscast whenever and however they wanted via their television or computer, as long as they had an internet connection. The results of this study show how the system was used,what specific actions were taken, and where the potential lies for further research.

Ultrafast charge and electron transfer, primary events in artificial photosynthesis, are key in solar energy harvesting. This dissertation provides insight into photo-induced charge and electron transfer in the donor and acceptor constructs built using a range of donor and acceptor entities, including transition metal dichalcogenides (TMDs, molybdenum disulfide (MoS2), and tungsten disulfide (WS2)), N-doped graphene, diketopyrrolopyrrol (DPP), boron-dipyrromethene (BODIPY), benzothiadiazole (BTD), free base and metal porphyrins, zinc phthalocyanine (ZnPc), phenothiazine (PTZ), triphenylamine (TPA), ferrocene (Fc), fullerene (C60), tetracyanobutadiene (TCBD), and dicyanoquinodimethane (DCNQ). The carefully built geometries and configurations of the donor and (D), acceptor (A), with a spacer in these constructs promote intramolecular charge transfer, and intervalence charge transfer to enhance charge and electron transfer efficiencies. Steady-state UV-visible absorption spectroscopy, fluorescence and phosphorescence spectroscopies, electrochemistry (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)), spectroelectrochemistry (absorption spectroscopy under controlled potential electrolysis), transient absorption spectroscopy, and quantum mechanical calculations (density functional theory, DFT) are used to probe ground and the excited state events as well as excited state charge separation resulting in cation and anion species. The current findings are useful for the increased reliance on renewable energy resources, especially solar energy.

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