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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A comparative study of engagement within an academical institution / Carel Frederick Meintjes

Meintjes, Carel Frederick January 2010 (has links)
One of the most valuable assets in any organisation is the employees, although a small percent of employees in organisations are truly motivated and energised. It is essential for organisations to look into the engagement of its employees. This mini-dissertation focuses on a comparative study of the occupational wellness between lecturers and the technical IT support staff of an academic institution of the North West province in South Africa. The objectives were to determine and compare the engagement of employees in the categories mentioned above. Thereafter a comparison was made with specific aspects of the work and work environment. Literary research was done in order to discuss and conceptualise terms such as wellness and health, occupational stress and occupational wellness. Thereafter the burnout and engagement concepts were discussed. Empirical research was done by using questionnaires that were disseminated among the two different employee groups identified for the study. Firstly, the Work and Well-being questionnaire was used to determine the work engagement levels of the different groups. This questionnaire focussed on the vigour, absorption and dedication dimensions of the study sample. In this survey the reliability indicated that all the dimensions of engagement were accepted and that employees of the IT support staff group have an overall higher level of work engagement than the lecturer group. Secondly, the Job Resources questionnaire was used to evaluate how specific aspects of the work and work environment are experienced by both IT personnel and lecturing personnel. Results gained from the Cronbach‟s alpha coefficient method indicated that the questionnaire regarding factors like emotional overload, achievement, collegiality, supervision, information regarding performance and satisfaction with pay were indicated as reliable and accurate. The results from the Job Resources questionnaire indicated that emotional overload and feelings of achievement in the work environment is higher in the IT group than for lecturers. The rest of the factors tested were significantly equal for both groups. The final chapter takes the information from the previous chapters to reach a conclusion. The key finding was that the IT sample has a higher level of absorption and dedication of engagement than the lecturer sample. Secondly, the findings were that the emotional overload and achievement for the sample population is higher for the IT staff than the lecturing staff. The collegiality, supervision, information regarding performance and satisfaction with pay were at the same level for both the IT group and lecturer group. Limitations were identified along with recommendations to the organisation and future research possibilities. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2010
2

A comparative study of engagement within an academical institution / Carel Frederick Meintjes

Meintjes, Carel Frederick January 2010 (has links)
One of the most valuable assets in any organisation is the employees, although a small percent of employees in organisations are truly motivated and energised. It is essential for organisations to look into the engagement of its employees. This mini-dissertation focuses on a comparative study of the occupational wellness between lecturers and the technical IT support staff of an academic institution of the North West province in South Africa. The objectives were to determine and compare the engagement of employees in the categories mentioned above. Thereafter a comparison was made with specific aspects of the work and work environment. Literary research was done in order to discuss and conceptualise terms such as wellness and health, occupational stress and occupational wellness. Thereafter the burnout and engagement concepts were discussed. Empirical research was done by using questionnaires that were disseminated among the two different employee groups identified for the study. Firstly, the Work and Well-being questionnaire was used to determine the work engagement levels of the different groups. This questionnaire focussed on the vigour, absorption and dedication dimensions of the study sample. In this survey the reliability indicated that all the dimensions of engagement were accepted and that employees of the IT support staff group have an overall higher level of work engagement than the lecturer group. Secondly, the Job Resources questionnaire was used to evaluate how specific aspects of the work and work environment are experienced by both IT personnel and lecturing personnel. Results gained from the Cronbach‟s alpha coefficient method indicated that the questionnaire regarding factors like emotional overload, achievement, collegiality, supervision, information regarding performance and satisfaction with pay were indicated as reliable and accurate. The results from the Job Resources questionnaire indicated that emotional overload and feelings of achievement in the work environment is higher in the IT group than for lecturers. The rest of the factors tested were significantly equal for both groups. The final chapter takes the information from the previous chapters to reach a conclusion. The key finding was that the IT sample has a higher level of absorption and dedication of engagement than the lecturer sample. Secondly, the findings were that the emotional overload and achievement for the sample population is higher for the IT staff than the lecturing staff. The collegiality, supervision, information regarding performance and satisfaction with pay were at the same level for both the IT group and lecturer group. Limitations were identified along with recommendations to the organisation and future research possibilities. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2010
3

Estágios de colheita e repouso pós-colheita dos frutos na qualidade de sementes de mamoneira

Silva, Líbia Belisário da [UNESP] 21 November 2007 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-21Bitstream added on 2014-06-13T20:48:34Z : No. of bitstreams: 1 silva_lb_me_botfca.pdf: 393551 bytes, checksum: 68ad65b5247076fa26c16688a2d0cd1d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O presente trabalho teve como objetivo avaliar o efeito dos estágios de colheita e do repouso pós-colheita dos frutos na qualidade de sementes de mamoneira (Ricinus communis L.) cultivar AL Guarany 2002. Foram avaliadas 9 épocas de colheita dos racemos, dos 30 até 142 dias após a antese (DAA), em intervalos de 14 dias e quatro condições de repouso: sem e com repouso de sete dias de sementes extraídas (nuas), de frutos e de frutos presos ao racemo. Foram avaliados a massa fresca dos frutos, as dimensões e a cor de frutos e sementes; o teor de água, matéria seca, germinação e vigor das sementes (primeira contagem de germinação, porcentagem de plântulas vigorosas, emergência de plântulas em areia, índice de velocidade de emergência e condutividade elétrica). O estágio de colheita e o repouso póscolheita afetaram a qualidade das sementes de mamoneira. Sementes com máxima qualidade fisiológica e matéria seca foram obtidas de frutos colhidos aos 86 DAA. A colheita pode ser realizada até os 128 DAA sem redução da germinação, mas com prejuízos devido à queda dos frutos, dispersão das sementes aos 100 DAA e reduções do vigor. O repouso das sementes nuas permitiu a antecipação da colheita para 72 DAA sem prejuízos à germinação e matéria seca, mas com reduções de vigor. A cor dos frutos, das sementes e o teor de água das sementes foram parâmetros eficientes para a identificação do ponto de colheita, principalmente se usados conjuntamente. / This study aims to assess the effect of the harvesting stages process and the resting period of the post-harvest of fruits in the quality of castor bean seeds (Ricinus communis L.) AL Guarany 2002. It were assessed nine times in racemes, from 30 to the 142 day after anthesis (DAA), at intervals of fourteen days and four conditions of resting period; without and with resting period of seven days of seeds extracted (bare), fruits and fruits prisioners to the raceme. The fruits weight, the dimension and the fruits colour and seeds were then assessed: the content of water, dry matter, seed germination and vigour (first of germination, percentage of vigorous seedlings, emergence of seedlings in sand, speed emergence index and electric conductivity). The harvest stage and the post-harvest resting period affected the quality of castor bean seeds. Seeds with maximum physiological quality and dry matter were obtained from fruit harvested at 86 DAA. The harvest can be achieved by the 128 DAA without reducing germination, but with losses due to falling fruit, seed dispersal to 100 DAA and reductions in strength. The rest seeds bare allows the harvest to be brought forward to the 72 DAA without detriment to the germination and dry matter, but with reductions in strength. The colour of the fruits, seeds, and water content of seeds were effective parameters for the identification of the harvest point harvest, particularly if used together.
4

The impact of job and organisational characteristics on engagement at work in a petrochemical company / Christian Johan Goosen

Goosen, Christian Johan January 2010 (has links)
In today's tough economic environment, companies are forced to work more efficiently and effectively with the resources they have at their disposal. At the same time companies are struggling to attract and retain good people with the necessary attributes and skills in order for them to remain competitive. The challenge today is not just retaining talented people, but fully engaging them, capturing their minds and hearts at each stage of their work lives. Employee engagement has emerged as a critical driver of business success in today's competitive marketplace. Further, employee engagement can be a deciding factor in organisational success. Not only does engagement have the potential to significantly affect employee retention, productivity and loyalty, it is also a key link to customer satisfaction, company reputation and overall stakeholder value. The purpose of this study is to determine whether job and organisational characteristics have an impact on work engagement. Weak correlation was found between the four aspects of Job and organisational characteristics namely: the Position the company holds in the industry, Own and company objectives, Environmental factors and Commitment or social responsibility position the company takes and the three aspects of Engagement namely Vigour, Dedication and practically significant correlation coefficients of large effect between Vigour on the one hand and Dedication and Absorption on the other hand. Practically significant correlation coefficients of large effect between Dedication on the one hand and Absorption on the other hand. Practically significant correlation coefficients of medium effect between Absorption on the one hand and Own and company objectives was found. After controlling for work engagement at baseline, only four of the dimensions tested between Job and organisational characteristics and Engagement were statistically significant. No positive association could be found between Job and organisational characteristics and Work Engagement. The findings are noteworthy in that all the aspects of Job and organisational characteristics do not lead to Engagement thus no evidence was found that Job and organisational characteristics could stimulate Work Engagement. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2011.
5

The impact of job and organisational characteristics on engagement at work in a petrochemical company / Christian Johan Goosen

Goosen, Christian Johan January 2010 (has links)
In today's tough economic environment, companies are forced to work more efficiently and effectively with the resources they have at their disposal. At the same time companies are struggling to attract and retain good people with the necessary attributes and skills in order for them to remain competitive. The challenge today is not just retaining talented people, but fully engaging them, capturing their minds and hearts at each stage of their work lives. Employee engagement has emerged as a critical driver of business success in today's competitive marketplace. Further, employee engagement can be a deciding factor in organisational success. Not only does engagement have the potential to significantly affect employee retention, productivity and loyalty, it is also a key link to customer satisfaction, company reputation and overall stakeholder value. The purpose of this study is to determine whether job and organisational characteristics have an impact on work engagement. Weak correlation was found between the four aspects of Job and organisational characteristics namely: the Position the company holds in the industry, Own and company objectives, Environmental factors and Commitment or social responsibility position the company takes and the three aspects of Engagement namely Vigour, Dedication and practically significant correlation coefficients of large effect between Vigour on the one hand and Dedication and Absorption on the other hand. Practically significant correlation coefficients of large effect between Dedication on the one hand and Absorption on the other hand. Practically significant correlation coefficients of medium effect between Absorption on the one hand and Own and company objectives was found. After controlling for work engagement at baseline, only four of the dimensions tested between Job and organisational characteristics and Engagement were statistically significant. No positive association could be found between Job and organisational characteristics and Work Engagement. The findings are noteworthy in that all the aspects of Job and organisational characteristics do not lead to Engagement thus no evidence was found that Job and organisational characteristics could stimulate Work Engagement. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2011.
6

Revestimento, qualidade física e fisiológica de sementes de cenoura (Daucus carota L.) cv. Brasília

Soares, Flávio Humberto [UNESP] 25 March 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-25Bitstream added on 2014-06-13T20:25:22Z : No. of bitstreams: 1 soares_fh_dr_jabo.pdf: 238041 bytes, checksum: 481057decfeee0952db8ea11272d6626 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cenoura é uma importante hortaliça no Brasil, com área de produção de cerca de 28.000 ha/ ano e a técnica de revestimento de suas sementes tem sido utilizada para fins de semeadura direta. Esta pesquisa foi realizada no Laboratório de Análise de Sementes do Departamento de Produção Vegetal da Faculdade de Ciências Agrárias e Veterinárias/UNESP, Câmpus de Jaboticabal, com o objetivo de avaliar quatro diferentes concentrações de revestimento em três calibres de sementes de cenoura nas qualidades física e fisiológica. Foram utilizados três lotes de sementes de cenoura (Daucus carota L.) cv. Brasília, originados de umbelas diferentes do mesmo florescimento, e revestidas por incrustação a 0%, 50%, 100%, 150% e 200% da massa específica da semente. Avaliaram-se os fatores físicos: Teor de Água, Pureza Física, Peso de 1000 sementes, Número de Sementes por Grama e Peso Volumétrico, e os fatores fisiológicos: Teste de Tetrazólio, Germinação e Emergência, e vigor pelos testes de Primeira Contagem de Germinação e Emergência e Índice de Velocidade de Germinação e Emergência. Para a análise estatística utilizou-se o delineamento inteiramente casualizado em esquema fatorial, com quatro repetições, e a comparação das médias foi feita usando-se o teste de Tukey ao nível de 5% de probabilidade. De acordo com os resultados obtidos concluiu-se que os calibres das sementes de cenoura submetidas aos testes de avaliação física respondem de forma diferente aos tratamentos de revestimento. A utilização da tecnologia de revestimento é recomendada pelo processo de incrustação de até 150% de concentração, pois não interfere de forma significativa aos principais testes de qualidade fisiológica das sementes de cenoura cv. Brasília, independente do calibre. / The carrot is an important vegetable in Brazil, with production area of about 28,000 ha / year and the technique of coating of the seeds have been used for tillage. This research was performed at the Laboratory of Seed Analysis, Department of Plant Production, Faculdade de Ciências Agrárias e Veterinárias/UNESP, Câmpus de Jaboticabal, to evaluate four different concentrations of coating on three sizes of seed of the carrot and physical qualities physiological. We used three seed lots of carrot (Daucus carota L.) cv. Brasília, originated from different umbels of the same flower, and covered with inlay of 0%, 50%, 100%, 150% and 200% of the density of the seed. We evaluated the physical factors: water content, physical purity, weight of 1000 seeds, number of seeds per gram and Volumetric Weight, and physiological factors: the tetrazolium test, germination and emergence, and force the testing of first count of germination and Emergency and speed of germination index and Emergency. For the statistical analysis used the completely randomized design in factorial with four replications, and comparison of means was made using the Tukey test at 5% level of probability. According to the results concluded that the sizes of the seeds of carrot subjected to tests of physical evaluation respond differently to treatment of coating. It is recommended to use the technology of coating by the process of incrustation of up to 150% concentration, it does not interfere in any significant way to the main test of physiological seed quality of carrot cv. Brasília, regardless of size.
7

Prediction of field emergence of maize (Zea mays L.) hybrids exposed to cold and wet conditions

Maree, Pieter Hermanus 12 August 2009 (has links)
The cold test is one of the oldest and most acceptable vigour tests as it is used to simulate stress conditions commonly occurring in the field. In recent years, some of South Africa’s top maize hybrids, with high cold test scores, have shown emergence problems under cold, wet planting conditions. It resulted in major complaints from commercial maize producers with sizable claims involved. Therefore, the need arose to find a more sensitive vigour test that takes into account cold, wet conditions. In practice, South African maize producers would not plant if it is too cold and wet. However, cold, wet conditions are commonly experienced during planting time in the main maize production regions of South Africa, especially during October and even November. Furthermore, in most of the commercial maize production areas, such as the western Free State, chances of thunder and hailstorms are high during the planting period. These weather conditions are major causes for sudden drops in temperature and flooding which can expose maize seed and emerging maize seedlings to stress conditions The effects of cold, wet conditions on germination and emergence of nine maize hybrids were investigated in laboratory, glasshouse and field experiments. Growth chamber and glasshouse experiments were conducted under 10°C, 20°C and 30°C and 0, 24, 48 and 72 hours flooding. Field experiments were conducted under different climatic conditions, resulting in cool and wet, cold and wet and favourable conditions during planting. The objectives were to investigate the correlations between different laboratory vigour tests and field emergence of maize hybrids under cold, wet conditions in order to identify the most suitable laboratory vigour test for predicting field emergence under cold, wet conditions. Eight different vigour tests were conducted and each was compared with field emergence under cold, wet conditions. The eight tests conducted, were the cold test, soak test, complex stressing vigour test, electrical conductivity test, accelerated ageing test, tetrazolium test, fast green test and emergence rate test. The soak test was the most sensitive vigour test when considering cold, wet conditions, as it measures seed germination, based on the warm test, after a 48 hour soak in water at 27°C. Correlations found between the soak test and field emergence (53%) under cold, wet conditions was unexpected, since the soak test does not account for low temperatures. The complex stressing vigour test was conducted to study the effect of fluctuating soaking temperatures on germination of maize seed. Seeds of nine maize hybrids were soaked for 48 hours at a moderate temperature (25°C), followed by another 48 hours soak at a low temperature (5°C), and then planted in sand and grown for 4 days at 25°C, before evaluation. Highly significant correlations were found between the complex stressing vigour test and simulated field emergence under both controlled conditions in a glasshouse (89.9%) and cold, wet conditions in the field (90.0%). The complex stressing vigour test was the best test to predict field performance under a wide range of climatic conditions, especially cold, wet conditions. Implementation of the complex stressing test as a routine vigour test, will be to the advantage of maize seed companies, especially in being proactive in predicting emergence of maize hybrids under cold, wet conditions. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted
8

Carotenoid and chlorophyll content of Vitis vinifera cv. Merlot grapes during ripening with reference to variability in grapevine water status and vigour

Kamffer, Zindi 03 1900 (has links)
Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Previous research has shown that carotenoids are precursors of C13-norisoprenoid aroma compounds in wine. C13-norisoprenoids have low threshold values in wine with the most prominent C13-norisoprenoids being β-damascanone and β-ionone which contribute honey and floral like aroma to wine. Chlorophyll and its derivates have also been detected in wine with potential to be precursors to aroma compounds. Apart from the contribution of these pigments to wine aroma and quality they are vital role players in photosynthesis and are widely found in plants and plant products. The main functions of these pigments in plants are light collection and light-protection. Research has shown that environmental conditions, climate, light exposure of bunches and soil water deficit influence the carotenoid content of grape berries. Furthermore the concentration of carotenoids and chlorophylls has also been shown to differ between cultivars. No research in this regard has been done on Merlot grape berries. With this in mind, the aim of this study was to evaluate the effect of vigour and soil water content on the evolution of carotenoids and chlorophylls through ripening of grape berries from the cv. Merlot. However, when looking at methods to analyse carotenoids and chlorophylls in berry tissue, especially lyophilised tissue, there were no readily available methods. Thus, an extraction method to identify and quantify the carotenoid and chlorophyll profile of lyophilised tissue from unripe (green) to ripe (red) Merlot grape berries was needed. In this study the RPHPLC method of Taylor et al. (2006) for carotenoids and the extraction method of Mendes-Pinto et al. (2004) were adapted to analyse both carotenoids and chlorophylls in lyophilised grape tissue. The RP-HPLC method baseline separated all the carotenoids and chlorophylls and their derivatives. Recovery of standards from mock extractions was high, indicating that the extraction procedure was acceptable. However, extraction recovery tested in the matrix of the grape tissue showed less promising results due to the high acid content of grape tissue. Violaxanthin, neoxanthin and the chlorophylls were especially sensitive to low pH conditions which facilitated their degradation. The degradation products of these compounds under acidic conditions were identified as pheophytin a, b, chlorophillide a, pyropheophytin b, cisviolaxanthin, cis-neoxanthin, neochrome, mutatoxanthin and luteoxanthin. There is a possibility that some degradation products were already present in the tissue due to lyophilisation (since the water in the berry was then removed and the acid concentrated). More work is needed to investigate the effect of lyophilisation and storage on the composition of grape tissue of different maturity. The extraction method for grape berry tissue at different ripening stages should also be optimised further to effectively neutralise tissue acidity, without compromising the extraction of carotenoids significantly, in especially green berry tissue. The question as to whether cisisomers and chlorophyll degradation products are naturally present in grape berries or are formed during sampling and processing remains unanswered in the current study. This study confirmed that in general carotenoids and chlorophylls decrease on a per berry (μg/berry) and concentration (μg/g) basis from veraison to harvest. Furthermore, this study was inconclusive in showing that vigour differences have an effect on the rate of synthesis/degradation of carotenoids, chlorophyll and some other ripening parameters, namely malic acid, total glucose and fructose, total tannin and total anthocyanin, from pre-veraison (pea size) to harvest. Additionally, no significant effect of soil water content on carotenoids, chlorophylls and ripeness parameters was found in this study, most likely due the fact that high soil water capacity was found in lower soil layers which may have prevented significant differences in grapevine water status. Experimental plots selected for vigour differences based on normalised difference vegetation index (NDVI) images, pruning mass and soil water measurements by means of a neutron probe, showed significant differences in soil water content in only the first 30 cm of the soil for the ripening seasons studied. Predawn plant water potential measurements, however, indicated that none of the experimental vines experienced severe water stress which was previously shown to effect carotenoid content of grapes. The carotenoid 5,8-epoxy--carotene was quantified for the first time in grapes and represents a significant amount of the total carotenoids present at harvest. All the carotenoids and chlorophylls except -carotene appeared to be sensitive to seasonal variation in climatic conditions. Lutein and β-carotene were found to be the most abundant carotenoids present in Merlot grape berries together with chlorophyll a for both seasons studied. The values of these carotenoids also correlated well with previous research. However, chlorophyll a was found in much larger quantities in Merlot berries compared to reported data. This is possibly because in this study the chlorophyll degradation products were included in the calculation of chlorophyll a. Multivariate analysis showed promising preliminary prediction models (with correlation values of above 0.8 for both seasons analysed) for the prediction of the concentration of ripeness parameters (glucose, fructose, malic acid, total tannins and anthocyanins) with carotenoid and chlorophyll content. This result highlights the opportunity for the development of a rapid non-destructive method to measure carotenoids and chlorophylls in berries which in turn can predict optimal ripeness. Furthermore, since carotenoids are the precursors to C13- norisoprenoid aroma compounds in wine a preview of the potential contribution of these aromas to wine might be evaluated. Further research is necessary to investigate the possibility of building and validating such models. / AFRIKAANSE OPSOMMING: Vorige navorsing het getoon dat karotenoïede die voorlopers is van C13-norisoprenoïed aromaverbindings in wyn. C13-norisoprenoïede het lae drempelwaardes in wyn, met β- damassenoon en β-jonoon as die prominentste C13-norisoprenoïede wat ‘n bydrae tot die heuning en blomagtige aroma van die wyn maak. Chlorofil en sy derivate is ook reeds in wyn bespeur, met die potensiaal om voorlopers van aromaverbindings te wees. Buiten die bydrae van hierdie pigmente tot wynaroma en -kwaliteit is hulle ook belangrike rolspelers in fotosintese en kom hulle wydverspreid in plante en plantprodukte voor. Die vernaamste funksies van hierdie pigmente in plante is om lig te versamel en om as beskerming teen lig op te tree. Navorsing het getoon dat omgewingstoestande, klimaat, ligblootstelling van die trosse en grondwatertekorte die karotenoïedinhoud van druiwekorrels beïnvloed. Verder is ook getoon dat die konsentrasie van karotenoïede en chlorofille tussen kultivars verskil. Geen navorsing is al in hierdie opsig op Merlot-druiwekorrels gedoen nie. Met hierdie aspek in gedagte was die doelwit van hierdie studie om die effek van groeikrag en grondwaterinhoud op die evolusie van karotenoïede en chlorofille tydens die rypwording van druiwekorrels van die cv. Merlot te evalueer. Wanneer mens egter kyk na die metodes waarvolgens die karotenoïede en chlorofille in korrelweefsel geanaliseer word, is daar geen geredelik beskikbare metodes nie. ‘n Ekstraksiemetode om die karotenoïed- en chlorofilprofiel van geliofiliseerde weefsel van onryp (groen) tot ryp (rooi) Merlot-bessies te identifiseer en kwantifiseer was dus nodig. In hierdie studie is die RP-HPLC metode van Taylor et al. (2006) vir karotenoïede en die ekstraksiemetode van Mendes-Pinto et al. (2004) aangepas om beide karotenoïede en chlorofille in geliofiliseerde druiweweefsel te analiseer. Die basislyn van die RP-HPLC metode het all karotenoïede en chlorofille en hul derivate geskei. Herwinning van die standaarde vanaf skynekstraksies was hoog, wat aandui dat die ekstraksieprosedure aanvaarbaar was. Ekstraksieherwinning wat in die matriks van die druiweweefsel getoets is, het egter minder belowende resultate getoon as gevolg van die hoë suurinhoud van die druifweefsel. Violaxantien, neoxantien en die chlorofille was veral sensitief vir toestande van lae pH, wat hulle afbreking gefasiliteer het. Die afbrekingsprodukte van hierdie verbindings onder suurtoestande is geïdentifiseer as feofitien a en b, chlorofillied a, pirofeofitien b, cis-violaxantien, cis-neoxantien, neochroom, mutatoxantien en luteoxantien. Daar is ‘n moontlikheid dat sommige afbreekprodukte reeds in die weefsel teenwoordig was as gevolg van liofilisering (aangesien die water in die korrel reeds verwyder was en die suur gekonsentreerd was). Meer werk is nodig om die effek van liofilisering en berging op die samestelling van druifweefsel van verskillende rypheid te bepaal. Die ekstraksiemetode vir druifkorrelweefsel op verskillende stadia van rypwording moet ook verder geoptimaliseer word om weefselsuurheid doeltreffend te neutraliseer, sonder om die ekstraksie van karotenoïede noemenswaardig te kompromitteer, veral in groen korrelweefsel. Die vraag of cis-isomere en chlorofil afbreekprodukte natuurlik in die druifkorrels teenwoordig is en of hulle tydens monsterneming en prosessering gevorm word, kon nie in hierdie studie beantwoord word nie. Hierdie studie het bevestig dat karotenoïede en chlorofille oor die algemeen op ‘n korrel (μg/korrel) en konsentrasie (μg/g) basis afneem vanaf deurslaan tot oes. Hierdie studie het nie daarin geslaag om te toon dat groeikragverskille vanaf voor-deurslaan (ertjiekorrelgrootte) tot oes ‘n effek het op die tempo van sintese/afbreking van karotenoïede, chlorofil en ander rypwordingsparameters nie, naamlik op appelsuur, totale glukose en fruktose, totale tannien en totale antosianien. Daar is ook in hierdie studie geen noemenswaardige effek van grondwaterinhoud op karotenoïede, chlorofille en rypheidsparameters gevind nie, heel moontlik as gevolg van die feit dat hoë grondwaterkapasiteit in die laer grondlae gevind is, wat betekenisvolle verskille in wingerdwaterstatus kon verhoed het. Eksperimentele persele wat gekies is vir groeikragverskille op grond van genormaliseerde verskil plantegroei indeks (NDVI) beelde, snoeimassa en grondwatermetings met ‘n neutronvogmeter het net in die eerste 30 cm van die grond noemenswaardige verskille in grondwaterinhoud getoon vir die rypwordingseisoene wat bestudeer is. Voor-sonopkoms plantwaterpotensiaalmetings het egter aangedui dat geen van die eksperimentele wingerdstokke ernstige waterstres ervaar het nie. Sulke stres is voorheen aangedui om ‘n effek op die karotenoïedinhoud van druiwe te hê. Die karotenoïed 5,8-epoksi--karoteen is vir die eerste keer in druiwe gekwantifiseer en verteenwoordig ‘n noemenswaardige hoeveelheid van die totale karotenoïede wat met oes teenwoordig is. Al die karotenoïede en chlorofille behalwe -karoteen blyk sensitief vir seisoenale verskille in klimaatstoestande te wees. Luteïen en β-karoteen was die volopste karotenoïede in die Merlot-druifkorrels, tesame met chlorofil a, vir beide seisoene wat bestudeer is. Die waardes van hierdie karotenoïede was ook goed gekorreleer met vorige navorsing. Chlorofil a is egter in baie groter hoeveelhede in Merlot-korrels gevind in vergelyking met dít wat in die data gerapporteer is. Die rede hiervoor is moontlik dat die chlorofil-afbreekprodukte in hierdie studie in die berekening van chlorofil a ingesluit is. Meerveranderlikeontleding het belowende voorlopige voorspellingsmodelle getoon (met korrelasiewaardes van meer as 0.8 vir beide die seisoene wat geanaliseer is) vir die voorspelling van die konsentrasie van rypheidsparameters (glukose, fruktose, appelsuur, totale tanniene en antosianiene) met karotenoïed- en chlorofilinhoud. Hierdie resultaat beklemtoon die geleentheid vir die ontwikkeling van ‘n vinnige, nie-destruktiewe metode om karotenoïede en chlorofille in korrels te meet, wat op sy beurt optimate rypheid kan voorspel. Aangesien karotenoïede die voorlopers van C13-norisoprenoïed aromaverbindings in wyn is, kan ‘n voorskou van die potensiële bydrae van hierdie aromas tot wyn moontlik verder evalueer word. Verdere navorsing is nodig om die moontlikheid van die bou en geldigheidsbepaling van sulke modelle te ondersoek.
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Job demands, job resources, and work engagement of employees in a manufacturing organisation / Michiel Frederick Coetzer

Coetzer, Michiel Frederick January 2006 (has links)
The manufacturing industry today is seen as a demanding world of work where employees are constantly exposed to high demands. This may have an influence on their work engagement levels and their organisational commitment. It seems that in these industries, employee turnover and absenteeism levels are high, while employees also seem to be demotivated in their work. The objective of this study was to investigate the levels of work engagement among employees in a manufacturing organisation and to assess which job demands and resources would predict work engagement. A random sample of 83 employees in a manufacturing organisation was taken. The Utrecht Work Engagement Scale (UWJ3S) and Job Demands- Resources Scale (IDRS) were used as measuring instruments. Descriptive statistics were used to explore the data Cronbach alpha coefficients were used to assess the internal consistency / reliability of the measuring instruments. Pearson correlation coefficients were used to specify the relationships between the variables. A multiple regression analysis was used to determine the effects of job demands and job resources on work engagement. The results of the Pearson Correlations showed that two job resources, namely organisational support (i.e. relationship with supervisor, role clarity, information, communication, and participation) and growth opportunities (i.e. variety in the job, opportunities to learn, and autonomy) were strongly related to the levels of work engagement. Social support (from colleagues) and advancement (i.e. remuneration, training and advawement opportunities) were moderately related to work engagement. The results of the regression analyses further indicated that an increase in two job resources, organisational support and growth opportunities, will probably increase the overall work engagement level of employee in a manufacturing organisation. The results also indicated that job demands (i.e. pace of work, quantitative workload, and emotional load) had a weak relationship with work engagement. Recommendations for future research were made. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.
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Conservação de sementes de açaí (Euterpe oleracea Mart.) / Conservation of Euterpe oleracea seeds

Nascimento, Walnice Maria Oliveira do 10 March 2006 (has links)
Sementes de Euterpe oleracea são consideradas recalcitrantes e demandam ampliação do conhecimento sobre os fatores que interferem na sua conservação. Diante disso, o presente trabalho objetivou verificar os efeitos do grau de umidade da semente e da temperatura do ambiente na manutenção da qualidade dessas sementes. Sementes da cultivar BRS Pará, com teores de água de 43,4%, 37,4%, 30,3%, 26,1%, 21,0%, 15,1% e 11,9%, acondicionadas em sacos de polietileno, foram armazenadas sob temperaturas de 20ºC, 15ºC e 10ºC, durante 360 dias e submetidas a avaliações periódicas do grau de umidade, da germinação, do vigor e da sanidade. A desidratação até 37,4% de água não produz efeitos imediatos sobre a germinação e o vigor das sementes. A partir de 37,4% de água, a dessecação favorece, progressivamente, a deterioração das sementes e ao atingirem 15,1% as sementes não germinam. Após o armazenamento, sementes com 21,0% de água ou menos têm a germinação anulada, independentemente da temperatura. A associação de 43,4% de água na semente e o armazenamento em ambiente a 20ºC, favorece a conservação das sementes por até 270 dias. / Seeds of Euterpe oleracea Mart. are considered recalcitrant and demand enlargement of the knowledge about the factors that interfere in its conservation. The present work aimed to verify the effects on seed moisture content and of the atmosphere temperature in the maintenance of seed quality. Seeds of cultivar BRS Pará, with moisture content of 43,4%, 37,4%, 30,3%, 26,1%, 21,0%, 15,1% and 11,9%, conditioned in polyethylene bags, were stored under controlled temperature at 20ºC, 15ºC and 10ºC, for 360 days, and submitted to periodic evaluations of the moisture content, germination, vigor and the health condition. The dehydration up to 37,4% of water does not produce immediate effects on the germination and vigour. However, after 37,4% it progressively favors the deterioration, and when reaching 15,1% the physiologic performance is annulled. After the storage, seeds with 21,0% of water or less have the germination annulled, independently of the temperature. It was verified that the association of seeds with 43,4% of water and the storage at 20ºC support the conservation of the seeds up to 270 days.

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