Cotyledonal- or transverse-cracking (TVC) in certain cultivars of snapbeans, Phaseolus vulgaris ~. seeds, clearly evident during germination, seriously places affected seedlings at a competitive disadvantage. TVC is an inherited trait and occurs across cell walls of cotyledons rather than along cell walls. Thus, it might be hypothesized that internal pressure resulting from swelling of storage proteins during imbibition might account for cellular rupture. To further elucidate this possibility, experiments were designed to compare electrophoretic patterns of storage proteins from seeds of snapbeans resistant and susceptible to TVC, and to correlate the different patterns of polyacrylamide gel el ectrophoretograrns of these proteins to TVC. One hundred seeds were selected randomly from a bulk sample of 225 g from each of 17 seed lots representing 15 cultivars, seed coats removed and cotyledons finely ground (60 mesh). Seed flours were defatted twi ce with hexane (50 ml / g) at 4°C and defatted flours reground with a mortar and pestle. Seed proteins were extracted in 0.5 M NaCl (solvent to four ratio of 10:1) at pH 7.5 for 1 h at 4oc with centrifugation at 10,000 g for 30 min. Separated proteins were subjected to electrophoresis under denaturing and non-denaturing conditions and molecular weight of different protein brands determined. Different protein banding patterns were identified and correlated to the TVC phenomenon. The data showed visual differences between banding patterns of resistant and susceptible cultivars. While the electrophoretic technique shows observable differences in cultivars expressing differential TVC, it is not clear which protein bands are associated with the TVC phenomenon. For plant breeders to employ this tool in screening for TVC resistant snapbean cultivars, further requirements are needed.

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Comparative physiological and biochemical studies were conducted with apple varieties which were susceptible (Granny Smith and Lady Williams) and resistant (Crofton) to superficial scald, to understand the mechanisms of scald aetiology. This provided a basis for the development of alternatives to diphenylamine to control the disorder in cool stored apples. The research confirmed earlier research, which showed that the typical scald symptoms were the result of the deposition of brown pigments on the tonoplast in hypodermal and epidermal cells. It has been generally accepted that these pigments were formed by the action of polyphenol oxidase (PPO) following its release from chloroplasts, as a result of membrane damage caused by the oxidation products of alpha-farnesene. However, intact and functional chloroplasts were observed in severely scalded peel tissue. It was proposed that peroxidase (POD) might play a more important role in scald development. The concept that the concentration of alpha-farnesene or its products was related to the severity of scald was examined, and results indicated that differences in scald susceptability were related to the ability of apple tissue to cope with oxidative stress at low temperatures rather than the concentration of alpha-farnesene. If alpha-farnesene has a scald promoting role, it may be as a participant in a free radical chain reaction rather than an initiator. Studies were conducted on the phenolic compounds present in apple peel, which led to the proposal that phenolics might confer scald resistance by conserving other antioxidants and preventing peroxidation of membrane lipids. An holistic model of scald development was proposed, which indicated that scald results from a chilling stress since scald only occurs at temperatures below 4 degrees C and only in apples in which the capacity to protect membranes from oxidative stress is low. The model proposed that POD may have a more important role than PPO in scald development than previously thought. / Doctor of Philosophy (PhD)

Information available in digital form has grown phenomenally in recent years. Finding the required information has become a difficult and challenging task. This is primarily due to the diversity and enormous volume of information available and the change in the nature of people now seeking information – from experts to ordinary users of desktop computers with varying interest and objectives. The problem of finding relevant information is further impacted by the poor retrieval effectiveness of most current information retrieval (IR) systems that are primarily based on keyword indexing techniques. Though these systems retrieve documents that contain those keywords specified in the query, the documents that are retrieved may not necessarily be in the context in which the user would have wanted them to be. This research works argues that exploiting the user’s context of the information need has the potential to improve the performance of information retrieval systems. Context can reduce the ambiguity by associating meanings to request/query terms, and thus limit the scope of the possible misinterpretations of query terms. A new way of defining context categories based on information type is proposed and this notion of context differs from the conventional way of defining information categories based on subject topics as it is closely linked with the situation in which the user’s needs for information originates. A new context-based information retrieval system where users could specify the context in which they are seeking information is presented. This work also includes a full-scale development, implementation and evaluation of the new context-based information system / Doctor of Philosophy (PhD)

Nectarines suffer low temperature disorders (LTD)when stored for more than 2 - 3 weeks at temperatures below 8 degrees C. LTD take the form of flesh bleeding and browning, loss of juiciness, development of mealiness and failure to ripen normally.It has been shown previously that adding about 15% CO2 to the storage atmosphere at 0 degrees C can delay the development of LTD in some cvv. of peaches and nectarines. The initial aim of this research was to explore the genetic basis of the differences among cultivars in the responses to high CO2.After much investigation, it was shown that both genetic and seasonal factors are involved in the development of LTD in nectarines. The development of LTD is a form of chilling injury since they only occur at temperatures below 8 degrees C. but there was no evidence of of a direct role for ethylene in either causing or delaying LTD. It was proposed that storage at low temperatures causes a metabolic imbalance resulting from changes in the amounts or activities of proteins associated with normal ripening. Proposals were presented to further examine protein expression using storage conditions that affect the rate of development of LTD. / Doctor of Philosophy (PhD)

Bibliography: leaves 137-156. / xiv, 166 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Horticulture, Viticulture and Oenology, University of Adelaide, 1993

Bibliography: leaves 137-156.

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<p>The topic of this thesis is the study of energy storage systems operating with wind power plants. The motivation for applying energy storage in this context is that wind power generation is intermittent and generally difficult to predict, and that good wind energy resources are often found in areas with limited grid capacity. Moreover, energy storage in the form of hydrogen makes it possible to provide clean fuel for transportation. The aim of this work has been to evaluate how local energy storage systems should be designed and operated in order to increase the penetration and value of wind power in the power system. Optimization models and sequential and probabilistic simulation models have been developed for this purpose.</p><p>Chapter 3 presents a sequential simulation model of a general windhydrogen energy system. Electrolytic hydrogen is used either as a fuel for transportation or for power generation in a stationary fuel cell. The model is useful for evaluating how hydrogen storage can increase the penetration of wind power in areas with limited or no transmission capacity to the main grid. The simulation model is combined with a cost model in order to study how component sizing and choice of operation strategy influence the performance and economics of the wind-hydrogen system. If the stored hydrogen is not used as a separate product, but merely as electrical energy storage, it should be evaluated against other and more energy efficient storage options such as pumped hydro and redox flow cells. A probabilistic model of a grid-connected wind power plant with a general energy storage unit is presented in chapter 4. The energy storage unit is applied for smoothing wind power fluctuations by providing a firm power output to the grid over a specific period. The method described in the chapter is based on the statistical properties of the wind speed and a general representation of the wind energy conversion system and the energy storage unit. This method allows us to compare different storage solutions.</p><p>In chapter 5, energy storage is evaluated as an alternative for increasing the value of wind power in a market-based power system. A method for optimal short-term scheduling of wind power with energy storage has been developed. The basic model employs a dynamic programming algorithm for the scheduling problem. Moreover, different variants of the scheduling problem based on linear programming are presented. During on-line operation, the energy storage is operated to minimize the deviation between the generation schedule and the actual power output of the wind-storage system. It is shown how stochastic dynamic programming can be applied for the on-line operation problem by explicitly taking into account wind forecast uncertainty. The model presented in chapter 6 extends and improves the linear programming model described in chapter 5. An operation strategy based on model predictive control is developed for effective management of uncertainties. The method is applied in a simulation model of a wind-hydrogen system that supplies the local demand for electricity and hydrogen. Utilization of fuel cell heat and electrolytic oxygen as by-products is also considered. Computer simulations show that the developed operation method is beneficial for grid-connected as well as for isolated systems. For isolated systems, the method makes it possible to minimize the usage of backup power and to ensure a secure supply of hydrogen fuel. For grid-connected wind-hydrogen systems, the method could be applied for maximizing the profit from operating in an electricity market.</p><p>Comprehensive simulation studies of different example systems have been carried out to obtain knowledge about the benefits and limitations of using energy storage in conjunction with wind power. In order to exploit the opportunities for energy storage in electricity markets, it is crucial that the electrical efficiency of the storage is as high as possible. Energy storage combined with wind power prediction tools makes it possible to take advantage of varying electricity prices as well as reduce imbalance costs. Simulation results show that the imbalance costs of wind power and the electricity price variations must be relatively high to justify the installation of a costly energy storage system. Energy storage is beneficial for wind power integration in power systems with high-cost regulating units, as well as in areas with weak grid connection.</p><p>Hydrogen can become an economically viable energy carrier and storage medium for wind energy if hydrogen is introduced into the transportation sector. It is emphasized that seasonal wind speed variations lead to high storage costs if compressed hydrogen tanks are used for long-term storage. Simulation results indicate that reductions in hydrogen storage costs are more important than obtaining low-cost and high-efficient fuel cells and electrolyzers. Furthermore, it will be important to make use of the flexibility that the hydrogen alternative offers regarding sizing, operation and possibly the utilization of oxygen and heat as by-products.</p><p>The main scientific contributions from this thesis are the development of</p><p>- a simulation model for estimating the cost and energy efficiency of wind-hydrogen systems,</p><p>- a probabilistic model for predicting the performance of a gridconnected wind power plant with energy storage,</p><p>- optimization models for increasing the value of wind power in electricity markets by the use of hydrogen storage and other energy storage solutions and the system knowledge about wind energy and energy storage that has been obtained by the use of these models.</p> / Paper 1 is reprinted with kind permission of ACTA Press. Paper 2 is reprinted with kind permission of Elsevier/ Science Direct. http://www.elsevier.com, http://www.sciencedirect.com Paper 3 is reprinted with kind permission of IEEE.