Theses & Dissertations - Retrospective (historical)

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This collection contains a growing number of digitized theses and dissertations published by University of Guelph graduate students prior to 2011.

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    Detection of Leptosphaeria Korrae, The Causal Agent of Necrotic Ring Spot, and its Occurrence in Southern Ontario
    (University of Guelph, Jan-94) O'Gorman, Daniel; Hsiang, Tom
    Isolations from 122 suspected necrotic ring spot (NRS) samples collected throughout southern Ontario, were used to confirm the presence of the disease in the province. Based on morphology of the sexual structures, Leptosphaeria korrae, the causal agent of NRS, was confirmed in 17 Ontario counties. To increase the efficiency of pathogen detection, an assay based on the polymerase chain reaction (PCR), was tested using the primer pair, LK17S/5.8SC, selected from the internal transcribed spacer region 1 of L. korrae ribosomal DNA. Specific amplification of L. korrae DNA was obtained, while no amplification occurred with DNA isolated from 15 other fungal species or healthy Kentucky bluegrass, the major host of NRS. The use of PCR with RAPD (random amplified polymorphic DNA) primers, allowed detection of genetic variability in L. korrae single spore siblings and isolates collected from a single field site. The distribution pattern of polymorphic isolates at the field site suggests both mycelial growth and released ascospores were involved in the spread of NRS.
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    Screening Ecotypes of Poa Annua var. Reptans for Susceptibility to Pink Snow Mould Caused by Microdochium nivale
    (University of Guelph, Apr-05) Cunningham, Martha; Dionne, Julie; Hsiang, Tom
    Annual bluegrass (Poa annua) ecotypes collected from golf course putting greens were evaluated for resistance to pink snow mould (Microdochium nivale) under natural and controlled conditions. Field plots consisted of thirty ecotypes transplanted into existing creeping bentgrass (Agrostis stolonifera) putting greens in the fall, which allowed the turf to cold acclimate. Inoculation occurred in early winter. Weekly visual evaluation conducted immediately after snowmelt over six weeks revealed significant differences in the ability of the ecotypes to resist pink snow mould attack and to recover after snowmelt. Cold chamber plots consisted of the same ecotypes used in the field study plus two bentgrasses transplanted into tubes. The ecotypes were acclimated in a cold chamber before they were inoculated with infested wheat bran. Visual evaluation during the incubation period revealed significant differences in the ability of the ecotypes and the bentgrasses to resist pink snow mould attack.
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    Bioassays to Detect Dissipation and Efficacy of Benomyl on Turf
    (University of Guelph, Nov-93) Liu, Leon Xuecai; Hsiang, Tom
    Paper disc, soil-agar pellet, turfgrass-agar pellet, thatch-agar pellet, and sample agar mixture bioassays were developed and evaluated for detection of the fungicide benomyl and its major fungitoxic product methyl 2-benzimidazole carbamate (MBC) in leachate, soil, turfgrass clippings, and thatch. The bioassays could detect benomyl and MBC residues with a limit of detection of 0.2 μg/g and a limit of quantitation of 0.5 μg/g. In vitro soil and thatch degradation studies showed a half-life for MBC of approximately 18 days in thatch and 4 to 5 weeks in soil, depending on soil type. An adsorption equilibrium with benomyl in solution was reached within 1 h for thatch and 2 to 4 h for soils. MBC adsorbed by thatch was as much as twice that adsorbed by a Fox sandy loam which may represent a typical soil found on golf courses in Southern Ontario. When MBC was applied at 10 μg/g, up to 90% of the chemical in thatch and 68% in soil were not extractable with water. Methanol could extract up to three times the fungicide from soil or thatch as could water. Laboratory and field experiments showed that the wetting agent Aqua-Gro (AG) (polyoxyethylene ester and ether of cyclic acid and alkylated phenols) significantly reduced adsorption of benomyl by creeping bentgrass thatch. With AG, significantly less fungicide was initially adsorbed and significantly more fungicide was later desorbed from the thatch layer by 20 mm of water irrigation. Aqua-Gro increased movement, uptake, and biological availability of the fungicide and resulted in a higher residue level of fungicide in the grass clippings. Tersan 1991 (50% benomyl) applied at 2 kg/ha with AG gave control of dollar spot disease as good as the full rate (3 kg/ha) without AG. Field studies also showed that core cultivation 1 or 7 days before fungicide application gave better and longer-lasting uptake of the fungicide by turfgrass and resulted in better control of dollar spot disease. Core cultivation one day before fungicide treatment gave the best results both in long-lasting uptake of benomyl and control of dollar spot disease.
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    A quantitative analysis of the effects of feeding and daily variation on plasma acid-base status in resting horses
    (University of Guelph) Smithurst, Kerri Jo; Geor, Raymond J.; Lindinger, M.
    This thesis investigated the main acid-base constituents in equine plasma that exhibit daily variation. A major focus was to determine total carbon dioxide concentration ([TCO2]). Jugular venous blood was sampled every 1 to 2-h over 25-h from 10 resting and either fasted or fed Standardbreds on a 3-wk conditioning program and racehorse diet. The independent variables, strong ion difference ([SID]), total concentration of weak acids and bases ([Atot]), and partial pressure of carbon dioxide (PCO2), were assessed to determine factors affecting hydrogen ion concentration ([H +]) and calculated [TCO2] using the physicochemical approach to acid-base balance. Variations were found in [glucose], haematocrit (Hct), plasma proteins ([PP]), chloride ([Cl-]), bicarbonate ([HCO3-]), [H+], [SID], [A tot] and PCO2; all of which appeared to be due to effects of feeding or dehydration. Mean [TCO2] varied up to 10 mmol/L throughout the day and 70% of the horses had a calculated measurement above 36.0 mmol/L.
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    National Postcolonial: Representations of the enemy within in Canada's national newspapers
    (University of Guelph) Smolash, Wendy Naava; Heble, Ajay
    This thesis examines current constructions of "the enemy within" in Canada's national newspapers through an analytical framework inspired by Noam Chomsky, Edward Said, and other theorists including Critical Whiteness scholars such as Richard Dyer. It theorizes national newspaper narratives through a counterdiscursive close reading of coverage of the "Project Thread" arrests over a three-month period in 'The Globe and Mail ' and 'The National Post'. This coverage of the "preventative detentions" of international students from Pakistan and India reveals patterns that resemble the racialized representation of bodies deemed "the enemy within" during World Wars One and Two. Through such factors as repetitions, juxtaposition, the nature of headlines, quotations, and images, and the placement and size of stories, this thesis argues, Canada's national newspapers privilege the circulation of dominant notions of "the enemy within," the axes of which are media(ted) discourses of "the Nation," "Muslims," "Immigrants," "Terrorism," and "Whiteness."
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    Removal of ibuprofen from wastewater: Conventional and membrane bioreactor treatment processes
    (University of Guelph) Smook, Tara M.; Zytner, Richard G.
    Pharmaceuticals are a growing concern because they are continually being introduced in the influent to municipal wastewater treatment plants (WWTPs). Understanding their removal mechanisms from available treatment processes is vital in preventing downstream contamination of our natural water resources. In this study, ibuprofen, a popular over-the-counter pain reliever, was monitored by taking wastewater samples throughout the City of Guelph municipal WWTP. The results showed greater than 99% of ibuprofen was removed in the aeration tank. Aerobic biodegradation was confirmed to be the dominant mechanism of ibuprofen removal. First-order kinetics were used to quantify ibuprofen biodegradation in a conventional WWTP aeration tank and in a membrane bioreactor (MBR) pilot plant. The rate constant, kbiol, for the conventional WWTP and the MBR were determined to be (-6.8 ± 3.3) L/g SS*d and (-8.4 ± 4.0) L/g SS*d, respectively. These two rate constants were found to be statistically similar. In addition, a biological nutrient removal (BNR) pilot system comprised of an anaerobic tank, an anoxic tank, and an aeration tank with a microfiltration membrane was sampled. Preliminary findings from the samplings suggest that ibuprofen can also be degraded anaerobically.
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    The first observed metal coordination of a 1,2,3-dithiazole: Towards the design of new molecular materials
    (University of Guelph) Smithson, Chad Steven; Preuss, K.E.
    This thesis is an investigation of naphtho[1,2-'d '][1,2,3]dithiazolyl-4,5-dione and its use as a spin bearing ligand. The synthesis of the ligand in the 1+, 0 and 1- oxidation states is given, with the neutral ligand found to dimerize in the solid state. Cyclic voltammetry in MeCN reveals an Ecell of 0.80 V vs SCE, and chemical reversibility of the E1/2(1-/0) (-0.02 V) and E1/2 (0/1+) (0.78 V) couples. Despite numerous efforts, the open shell 2- oxidation state could not be stabilized. The first coordination species of a 1,2,3-DTA complex are provided with coordination of this ligand to Sb 5+, Ga3+ and Fe3+. Coordination occurs through the quinone oxygen atoms with the ligand always in the closed shell 1- oxidation state as determined from bond lengths. The crystal packing is observed to be largely governed by electrostatics, forming long chains through close SC???l and SO??? interactions.
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    Characterization of ProQ: An RNA binding protein modulating expression of the osmosensor and osmoregulator ProP of Escherichia coli
    (University of Guelph) Smith-Frieday, Michelle N.; Wood, Janet M.
    The ability to both sense and respond to variations in osmolality is essential for the survival of organisms inhabiting environments of extreme or varying osmolalities. ProP is an H+-osmoprotectant symporter that transports osmoprotectants into 'Escherichia coli' Following osmotic upshifts. In the absence of ProQ, the osmotic activation of ProP is reduced in amplitude as ProQ acts to amplify ProP activity at a post-transcriptional level. ProQ contains two distinct domains. The N-terminal domain of ProQ has a circular dichroism (CD) spectrum characteristic of alpha-helical structure, and through homology can be modeled on the crystal structure of the alpha-helical mRNA-binding protein FinO. The C-terminal domain of ProQ has a CD spectrum characteristic of beta sheet structure and can be modeled on the structure of the RNA chaperone Hfq. Functional characterization of these domains shows that the N-terminal domain of ProQ alone is able to partially complement a ' proQ' deletion. Full amplification of ProP activity is not seen, however, unless both the N- and C-terminal domains of ProQ are expressed. Deletion mutations within the 'proU' open reading frame, which encodes a second osmoregulatory transporter in 'E. coli' with a similar substrate specificity to ProP, suppressed the 'proQ' phenotype. Further analysis of this phenomenon revealed that suppression occurs in the absence of the 'proU' coding sequence, rather than in the absence of ProU transport activity. Observations presented here suggest that ProQ acts to amplify 'proP' expression by interacting with a small non-coding RNA (sRNA) and that this sRNA is either encoded within, or regulated by the expression of the 'proU' operon.
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    Exploring the source water protection interface between Six Nations of the Grand River and the province of Ontario
    (University of Guelph) Smith, Suzanne M.; Plummer, Ryan; Kreutzwiser, Reid
    First Nations in Canada do not enjoy the same level of drinking water quality as other Canadians. Watershed-scale source water protection has been advanced as a rational and efficient means of improving First Nation drinking water quality. However, First Nation source water protection governance is complex due to fragmented jurisdiction over water on reserves. The intent of this research is to explore the source water protection interface between Six Nations of the Grand River and the Province of Ontario. To satisfy this aim, a case study research design was employed. Data was collected through document analysis, observations, interviews, and workshops, and analyzed through open and axial coding. A narrative of source water protection in Six Nations was written, and the strengths, weaknesses, opportunities, and threats to the source water protection interface were then discussed in the context of watershed governance. The research revealed that differences in implementation, politics, and roles constrain effective, watershed-scale source water protection across reserve boundaries. Watershed-scale source water protection governance between First Nations and Ontario is enhanced by informal relationships between watershed actors.
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    Assessing the process of researching a sensitive subject in a cross-cultural setting: An example from Botswana
    (University of Guelph) Smith, Stephanie; Reid, Donald G.
    Millions of women and children suffer from sexual violence and abuse everyday. It is a serious and pervasive issue which has impeded human development for many years and which is considered endemic throughout the developing world, including Africa. There are several socioeconomic and health implications for women survivors of rape and sexual abuse, and which serve as impediments to achieving a higher quality of life. For many researchers however, research studies and methods of data collection in this area are often hampered by the inability to elicit information concerning what many individuals consider to be a 'sensitive subject'. Rape and sexual abuse are no exception in this matter, since it is often located within traditional cultural and societal norms with regards to sexuality. The question this raises for researchers then is: how do we go about researching a sensitive subject in a cross-cultural setting? This study seeks to describe the process of doing feminist participatory research using an evaluation of a rape crisis centre in Botswana as an example. Observations of this process reveal that the feminist participatory model supports an environment conducive to working in collaboration with communities and organizations in a cross-cultural setting. As a result, researchers are provided with valuable insights and information regarding a sensitive subject that they might not otherwise obtain. However, this study revealed several problems which most feminist writers neglect: the feminist participatory model is limited by the idea that women are 'inherently' cooperative and collaborative. As such, this model does not have the power to transcend the cultural barriers surrounding sensitive subjects.
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    Crop insurance and farm management of weather-related risks
    (University of Guelph) Smithers, Cindy; Smit, Barry
    Agricultural crop-based operations inevitably experience risk related to weather variability. How farmers cope with these weather-related risks, both throughout the growing season and from year to year, is not well understood due to the complexity of the decision making process. Farmers may choose from a range of production, financial and marketing strategies that function to alleviate the risk associated with weather. One option currently available to farmers to manage the risk associated with weather is crop insurance. This research addresses the question of how farmers employ crop insurance in the management of weather-related risks. Soybean production, in particular, is examined as it is sensitive to weather and because it is a major cash crop in Ontario. Provincial level data are employed to provide an understanding of the types of relationships which may be expected to occur between weather variability and crop insurance use. However, this level of examination relies on assumptions about behaviour and decision making. A farm level survey of soybean producers in Middlesex County provides an improved understanding of how crop insurance is used to manage weather-related risks by farmers. This research concludes that soybean producers in Middlesex County employ crop insurance to manage the weather risks which predominantly interfere with the planting schedule. While some soybean producers in Middlesex County tend to employ crop insurance as part of a suite of risk management strategies, others are substituting alternative income protection strategies to alleviate the risk associated with weather.
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    Characterizing vascular expression of Tie2/Tek during breast cancer progression
    (University of Guelph) Smith, Mackenzie Jonathan; Coomber, Brenda L.
    Clinical efficacy of targeted anti-angiogenic therapy is dependent on target molecule expression by tumor blood vessels. Utilizing dual-immunostaining we have demonstrated marked heterogeneity in breast tumor blood vessel expression of the endothelial receptor tyrosine kinase Tie2, phosphorylated Tie2 (pTie2Y1100) and coverage by PDGFR-[beta]-positive pericytes, relative to the pan-endothelial marker CD31. In human breast tumors, the relative proportion of Tie2- and PDGFR-[beta]-positive blood vessels did not correlate to histopathological markers of tumor progression or overall patient survival. In tumors from MMTV-PyVmT transgenic mice, the relative proportion of Tie2-positive vessels was unrelated to tumor grade, while the proportion of pTie2Y1100-positive vessels increased with increasing nuclear grade. These results highlight the need to better understand the factors responsible for Tie2 and PDGFR-[beta] expression by breast tumor endothelial cells and pericytes, respectively, which may aid in enhancing patient selection for targeted anti-angiogenic therapies, and ultimately improve clinical benefit of such therapies.
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    Examining the transmission of values between generations
    (University of Guelph) Smith, Michelle D.; Norris, Joan E.
    There has been concern that familial bonds have weakened due to disruptive changes in today's society. However, researchers suggest that intergenerational relationships may be stronger than in previous years due to individuals living longer and the resulting increase in the number of shared years. By means of a questionnaire, 84 respondents (divided into 3 age groups: 65+, 31-64, 18-30) indicated the 3 most important values their grandparents and parents passed on to them. They were then asked to choose 3 values that are the most important to pass on to their own children. In addition, participants completed a family connections questionnaire asking detailed questions about the frequency of contact and closeness of their relationships with their grandparents, parents and children. Results indicated that there is considerable value overlap perceived among the generations. In particular, the 65+ group was more likely to perceive value similarity compared to the 18-30 age group. It was also found that this value similarity is influenced by the closeness of the relationship. The implications of these results are discussed with reference to the intergenerational stake hypothesis, the theory of intergenerational solidarity, and Erikson's concepts of identity and generativity.
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    Mirrored representation: Canada's Aboriginal Peoples and Parliament
    (University of Guelph) Smith, Loretta; McKenzie, J.
    This thesis is an investigation of why the Aboriginal Peoples of Canada are severely under-represented in the country's legislative institutions. It compares the number of candidates who received endorsement by mainstream political parties in the 2004 and 2006 federal general elections. The analysis specifically considers six hypotheses and how they might correlate to the rate of success of Aboriginal candidates. Based on this analysis, it is argued that Aboriginal peoples are disproportionately under-represented in Canadian legislatures vis-a?-vis their share of the population. At a minimum, they should occupy a proportionate share of legislative seats as their share of the population suggests. The primary vehicle for increasing the numeric representation of Aboriginal peoples in Canadian legislatives is via several reforms to Canada's electoral and party systems.
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    Garry oak savannah stand history and change in coastal southern British Columbia
    (University of Guelph) Smith, Shyanne; Gedalof, Ze'ev
    In this thesis I investigate the history of Garry oak (' Quercus garryana') savannah patches in coastal British Columbia and the changes to these ecosystems over recent centuries. Remnant Garry oak patches have been altered by agriculture, development, increased herbivory, exotic plants, and fire suppression. Identifying the historical stand structure and ecosystem processes is therefore critical for effective site management and restoration. In this study, tree-ring analysis was used to reconstruct the stand and disturbance history at eight Garry oak communities within and adjacent to the Gulf Islands National Park Reserve. Varying levels of disturbance and tree establishment were found to have occurred at the time of European settlement. After the initial colonization by Garry oak, Douglas-fir ('Pseudotsuga menziesii') recruitment increased and has been ongoing. Results from the smaller islands suggest that local environmental conditions, weather events, and competitive interactions are important controls of ecosystem dynamics on these sites.
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    The Lacs des Loups Marin harbour seal, Phoca vitulina mellonae Doutt 1942: Ecology of an isolated population
    (University of Guelph) Smith, Richard John; Lavigne, D.M.
    Investigations were undertaken to determine to what extent the Lacs des Loups Marins harbour seal ('Phoca vitulina mellonae') is distinct and isolated from oceanic harbour seals. The population occurs in the area of Lacs des Loups Marins (Lower Seal Lakes) (56-57°N, 73-74°W), 160 km East of Hudson Bay, on the Ungava peninsula of northern Que?bec. Written references to the unique appearance and behaviour of this seal date back to 1818. The subspecies was described primarily on the basis of a characteristic morphology and presumed long-time geographic isolation from neighbouring oceanic harbour seals. A craniometric analysis of 'P. v. mellonae' confirmed that it is morphologically distinguishable from oceanic harbour seal subspecies in the Atlantic and Pacific. There was also evidence of behavioural differences: Pupping seems to take place substantially earlier (early May) than in other harbour seal populations at similar latitudes. An analysis of DNA sequences from the mitochondrial control region indicated that the Lacs des Loups Marins animals exhibit some haplotypic divergence from other harbour seals. Analyses of stable isotope ratios in hair and fatty acid signatures in blubber indicated that 'P. v. mellonae' feeds exclusively in freshwater. Monitoring of the movements of eight freshwater animals with satellite telemetry over portions of a two year period provided further evidence that not only are the seals resident within the Lacs des Loups Marins area, but that individual animals exhibit considerable site fidelity. The differentiation exhibited by 'P. v. mellonae' is similar to that demonstrated by isolated ringed seal populations in Lakes Saimaa, Finland ('Pusa hispida saimensis ') and Ladoga, Russia ('P. h. ladogensis'). The totality of the evidence collected provides support for the designation of the Lacs des Loups Marins seal as a distinct subspecies. The population warrants classification as an Evolutionarily Significant Unit. The information gathered on the range of 'P. v. mellonae' has implications for future efforts to conserve the population, which is now listed as "vulnerable" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
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    Evaluation of barley yellow dwarf virs under conservation tillage practices in winter wheat
    (University of Guelph) Smith, Jocelyn L.; Schaafsma, Arthur W.; Sears, M.K.
    Barley yellow dwarf virus (BYDV) (Luteoviridae) is the most damaging viral disease of cereals worldwide. Due to increased adoption of conservation tillage practices in winter wheat production in south-western Ontario, it was suspected that BYDV incidence may have increased due to reduced destruction of volunteer wheat and earlier planting dates. It was hypothesized that volunteer wheat could serve as a reservoir for cereal aphids that transmit BYDV and provide a 'green bridge' to autumn sown winter wheat. Over two years of study, the incidence of BYDV in winter wheat and fields containing volunteer wheat was assessed and the most prevalent serotype(s) were determined. The most abundant vector species was determined as well as the seasonal dispersal patterns of cereal aphids by monitoring field populations and catches in suction air and elevated pan traps. Chloronicotinyl seed treatments were evaluated for their efficacy in controlling cereal aphids and BYDV.
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    Evolution of genome size in bats (Mammalia: chiroptera)
    (University of Guelph) Smith, Jillian Dinah Leigh; Gregory, T.R.
    This thesis concerns genome evolution in mammals, using the order Chiroptera to test hypotheses concerning the influence of biological traits on genome size. In 164 species of bats, genome size varied from 1.63 pg in ' Lophostoma carrikeri' to 3.17 pg in 'Rhinopoma hardwickii', averaging 2.35 pg ± 0.02SE. 43 estimates represented species from the previously unstudied family Pteropodidae ("megabats"). Consistent with previous hypotheses on genome evolution in bats (and flying vertebrates), bats have constrained genomes relative to other mammals, implying a link between genome size and the origins of flight. Surprisingly, megabats have even more highly constrained genomes than microbats. However, unlike patterns observed in avian species, bats did not show any relationships between genome size and metabolism, or flight-related characteristics. Rather, body size (or some other trait relating to it) seems to be a more relevant biological factor explaining the current extent of genome size variation in bats.
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    Season and management related changes in the diversity of nitrifying and denitrifying bacteria in an Ontario agricultural soil
    (University of Guelph) Smith, Jillian M.; Dunfield, Kari E.
    This research assessed the effects of seasonal variation and tillage practice on the diversity of nitrous oxide producing bacteria in agricultural soil and investigated the dynamics of denitrifiers in a thawing soil in the laboratory. Diversity of the nitrifier and denitrifier communities was assessed by PCR-denaturing gradient gel electrophoresis (DGGE) using primer pairs targeting functional genes. Analysis revealed that seasonal variation had the largest influence on diversity; while tillage practices also influenced the diversity of the microbial communities. Diversity of the communities was the lowest in February, in frozen soils, and rapidly increased in March, after a spring thaw event. The laboratory study indicated that active denitrifiers were related to 'N'2'O' emission during this time, with increased diversity and richness associated with increased ' N'2'O'. Insight into the effects of tillage and seasonal variation on these microbial communities has the potential of improving our understanding of the mechanisms of 'N'2 'O' emissions.
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    Pasteurization of raw skim milk by pulsed electric fields and antimicrobials
    (University of Guelph) Smith, Keith H.; Mittal, G.S.
    This thesis is an investigation of the microbial inactivation in raw skim milk by pulsed electric field treatment and antimicrobials nisin and lysozyme. The innovative technology of using a high-voltage pulsed electric field (PEF) for pasteurizing milk offers advantages of low processing temperatures and low energy utilization, while inactivating pathogenic micororganisms especially when combined with other preservation methods. A 7.0 log reduction of microorganisms found in raw skim milk has been achieved through a combination of pulsed electric field treatment (80 kV/cm, 50 pulses), mild heat (52°C) and addition of the natural antimicrobial peptides nisin (3000 IU/ml) and lysozyme (100 [mu]g/ml). The combination of PEF, mild heat and antimicrobials resulted in a much higher microbial inactivation than the sum of the individual reductions achieved from each treatment alone, indicating synergy. Varying the pH from 6.7 to 5.0 had no effect on microbial inactivation.