Microbes have a remarkable ability to adapt to a host of environmental stressors, including low temperature, high pressure and osmotic stresses. The adaptations of resistant microbes to low temperatures are varied, and may include the accumulation of solutes to maintain osmotic balance, the production of antifreeze proteins (AFPs) or ice nucleation proteins (INPs) to manipulate ice growth or formation. AFPs depress the freezing point, inhibit ice recrystallization, and have been reported to inhibit or delay the growth of gas hydrates. Conversely, INPs precipitate ice formation at relatively high subzero temperatures. Collectively, these activities can be described as ‘ice-association’ activities. Here, ice-affinity and/or freeze-thaw cycling were used to either select for isolates with ice association properties or to assess the low temperature resistance of microbial consortia derived from various environments. Ice-affinity successfully selected psychrotolerant microbes from cultured temperate and boreal soils, some of which had been previously reported in glaciers and Arctic/Antarctic sites. Many of the recovered microbes demonstrated ice-association activities. Freeze-thaw selection also greatly decreased the abundance and diversity of consortia from distinct sites, and allowed the recovery of individual isolates, many of which demonstrated ice-association. Freeze-thaw selection was also used to assess the role of cross-tolerance between osmotic and freeze-thaw stresses, based on the common challenge of desiccation. Microbial consortia from lakes with varying degrees of salinity were subjected to freeze-thaw stress, and the consortia from more saline lakes tended to show greater low temperature resistance. While few of the recovered microbes demonstrated ice-association activities, those from the more saline lakes tended to contain a higher intracellular solute concentration and were more likely to form biofilms. This underscores the diversity of resistance strategies and supports the notion of cross-tolerance. To determine if these selective regimes would have applications for hydrate growth inhibition, microbes derived from an oil well sample were subjected to freeze-thaw stress. Selection reduced microbial abundance, shifted the diversity, and resulted in the recovery of microbes with some ice-association activity. Taken together, this thesis demonstrates that the application of low temperature stress can be used to successfully investigate stress resistance mechanisms within microbial communities from distinct environments. / Thesis (Ph.D, Biology) -- Queen's University, 2010-09-21 15:58:14.932

No description available.

In this thesis freeze-thaw along roads in northern Sweden is examined. The examinations are put in a context of changing climate and its amplification towards the Arctic region on earth. The research focuses on the impact of a warmer climate on ground freeze-thaw and in exten- sion road maintenance in the region. The investigation is presented through two scientific papers, where the first examines how ground temperatures are developed during a single frost season experiment, where a natural accumulation of snow cover and a continual removal of snow cover occur respectively. In the second paper, ground temperature data from sub-Arctic Sweden that has been logged by the Swedish Transport Administration, has been collected and freeze-thaw cycles have been calculated and analysed. The results are related to regional landscape factors and are in the context of regional climate change discussed to reach understanding of challenges for road maintenance in the region and opportunities to reach resilience. The results in Paper 1 show that also a thin cover of snow has impact on the freeze-thaw frequency, duration and intensity that occur in and on the surface of the ground. Furthermore the results show that the ground temperatures rise in due to an increase in snow cover amounts and that this process occurs in several steps. Paper 2 shows that the occurrence of ground freeze-thaw is affected by the proximity to open waters. Warmer temperatures in the air may cause later ice freeze-up and earlier ice break-up on lakes, rivers and on the Gulf of Bothnia and roads in northern Sweden are in general situated on the coast or near rivers. Ground temperatures around 0 °C has a high negative impact on road stability and a warmer and wetter climate in northern Sweden may thus increase road deterioration. The economic development in Sweden stays dependent on extraction of natural resources in sub-Arctic Sweden and thus it is of major concern to main- tain and improve road infrastructure in the region.

In the annals of Soviet historiography, discord and rebellion mark the cultural form of the Khrushchev Thaw. Following the U.S.S.R.s loss of its Great Leader in 1953, a diffusion of political authority met a re-evaluation of established ideology; the dominant discourse of Soviet socialism shifted and, through the subsequent clash of orthodox and liberal forces, imparted a critical aesthetic to 1950s Soviet culture. But while the narrative of dissonance privileged by most historical texts cites the sharpness of post-Stalinist art, poetry, and literature as external evidence of a struggle, little attention has been paid to the internal logic of cultural production. Soviet cultural communication based itself on a mutual mythology that pursued both a dialogue of inclusivity and a sense of accountability. By re-examining how producers of culture managed their responsibilities to the state, to the public, and to their art against the Soviet ideal of the collective and its discourse of comradely persuasion, this thesis pursues the expression of Soviet thought by way of Soviet ideology in the malleable discourse of 1953-1958. / Graduate / 0582 / 0724

Retrogressive thaw slumps are one of the most dramatic thermokarst landforms in periglacial regions. This thesis investigates the impacts of two of the largest hillslope thaw slumps on the geochemistry of periglacial streams on the Peel Plateau, Northwest Territories. It aims to describe the inorganic geochemistry of runoff across active mega-slumps, impacted and pristine tundra streams, as well as that of the ice-rich permafrost exposed in the slump headwalls. Slump runoff is characterized by elevated suspended sediments (911 g/L), high conductivity (2700 µS/cm), and high SO42- ( up to 2078 ppm). The runoff originates as a solute-rich meltwater near the slump headwall, and leaches and re-dissolves soluble salts (e.g., gypsum) as it flows along the mudflow. Conductivity increases until the runoff mixes with pristine tundra streams, diluting the slump runoff signal. SO42-/Cl- is used as a tracer to isolate the slump runoff signal in impacted waters, and suggests that the contribution of slump runoff to the Peel River has been increasing since the 1960s.

In the annals of Soviet historiography, discord and rebellion mark the cultural form of the “Khrushchev Thaw.” Following the U.S.S.R.’s loss of its Great Leader in 1953, a diffusion of political authority met a re-evaluation of established ideology; the dominant discourse of Soviet socialism shifted and, through the subsequent clash of orthodox and liberal forces, imparted a critical aesthetic to 1950s Soviet culture. But while the narrative of dissonance privileged by most historical texts cites the sharpness of post-Stalinist art, poetry, and literature as external evidence of a struggle, little attention has been paid to the internal logic of cultural production. Soviet cultural communication based itself on a mutual mythology that pursued both a dialogue of inclusivity and a sense of accountability. By re-examining how producers of culture managed their responsibilities to the state, to the public, and to their art against the Soviet ideal of the collective and its discourse of comradely persuasion, this thesis pursues the expression of Soviet thought by way of Soviet ideology in the malleable discourse of 1953-1958. / Graduate / 0582 / 0724

No description available.

Cryopreservation of epididymal spermatozoa may be the only opportunity to preserve valuable genetics of males in cases of unforeseen injury or death. Stallion epididymal spermatozoa have been cryopreserved successfully and it has been demonstrated that stallion epididymal spermatozoa are fertile, and pregnancies as well as live foals have been produced. As spermatozoal quality parameters like motility, morphology and viability have a major influence on fertility and pregnancy rates, it is of great interest to describe these and investigate the influence of seminal plasma on these parameters. Fresh and post-thaw parameters (motility, morphology and viability) of stallion epididymal spermatozoa that have been and that have not been exposed to seminal plasma were evaluated, and directly compared to fresh and post-thaw parameters of ejaculated spermatozoa from the same stallions. Six sperm categories of each stallion (n= 4) were evaluated for motility, morphology and viability. These categories were fresh ejaculated spermatozoa (Fr-E), fresh epididymal spermatozoa that had been exposed to seminal plasma (Fr-SP+), fresh epididymal spermatozoa that had never been exposed to seminal plasma (Fr-SP-), frozen-thawed ejaculated spermatozoa (Cr-E), frozen-thawed epididymal spermatozoa that had been exposed to seminal plasma prior to freezing (Cr-SP+) and frozen-thawed epididymal spermatozoa that had never been exposed to seminal plasma (Cr-SP-). Results show that seminal plasma stimulates initial motility of fresh epididymal stallion spermatozoa while this difference in progressive motility is no longer present post-thaw; and that progressive motility of fresh or frozen-thawed ejaculated stallion spermatozoa is not always a good indicator for post-thaw progressive motility of epididymal spermatozoa. This study shows that seminal plasma has a positive influence on the incidence of overall sperm defects, midpiece reflexes and distal cytoplasmic droplets in frozen-thawed stallion epididymal spermatozoa while the occurance of midpiece reflexes is likely to be linked to distal cytoplasmic droplets. Furthermore, we could show that seminal plasma does not have an influence on viability of fresh and frozen-thawed morphologically normal epididymal spermatozoa. In conclusion, we recommend the retrograde flushing technique using seminal plasma as flushing medium to harvest and freeze stallion epididymal spermatozoa. AFRIKAANS : Bevriesing van epididimale spermatozoa mag die enigste geleentheid wees om waardevolle genetika van manlike diere te bewaar in die geval van onverwagse dood of besering. Epididimale spermatozoa van hingste is al suksesvol bevries, is bewys vrugbaar te wees en dragtighede sowel as lewendige vullens is deur die gebruik daarvan gelewer. Aangesien maatstawwe van spermgehalte soos beweeglikheid, morfologie en lewensvatbaarheid ‘n beduidende invloed uitoefen op vrugbaarheid en dragtigheidsyfers, is dit van groot belang om hierdie maatstawwe te omskryf en die invloed van seminale plasma daarop te ondersoek. Vars en ontdooide maatstawwe (beweeglikheid, morfologie en lewensvatbaarheid) van hings epididimale spermatozoa wat of aan seminal plasma blootgestel is of nie, is vergelyk met vars en ontdooide maatstawwe van geejakuleerde spermatozoa. Ses spermkategorieë van elke hings (n=4) is geevalueer vir beweeglikheid, morfologie en lewensvatbaarheid. Die kategorieë was vars geejakuleerde spermatozoa (Fr-E), vars epididimale spermatozoa wat blootgestel is aan seminale plasma (Fr-SP+), vars epididimale spermatozoa sonder blootstelling aan seminale plasma (Fr-SP-), ontdooide geejakuleerde spermatozoa (Cr-E), ontdooide epididimale spermatozoa blootgestel aan seminale plasma voor bevriesing (Cr-SP+) en ontdooide epididimale spermatozoa wat nooit blootgestel is aan seminale plasma nie (Cr-SP-). Uitslae toon dat seminale plasma die aanvanklike beweeglikheid van vars epididimale hings spermatozoa stimuleer, terwyl die verskil in lynbeweeglikheid nie meer teenwoordig is na ontdooiing nie; dat lynbeweeglikheid van vars epididimale spermatozoa of ontdooide geejakuleerde hings spermatozoa nie altyd ‘n goeie aanduiding is vir lynbeweeglikheid na ontdooiing nie. Hierdie studie toon dat seminale plasma ‘n positiewe invloed het op die voorkoms van algehele spermdefekte, midstukreflekse en distale sitoplasmiese druppeltjies in ontdooide hings epididimale spermatozoa terwyl die voorkoms van midstuk reflekse waarskynlik verband hou met distale sitoplasmiese druppletjies. Verder kon ons ook aantoon dat seminale plasma geen invloed het op die lewensvatbaarheid van vars en ontdooide morfologies normale epididimale spermatozoa nie. Ten slotte beveel ons aan dat retrograadse spoeling met seminale plasma as spoelmedium gebruik word wanneer hings epididimale spermatozoa versamel en bevries word. / Dissertation (MSc)--University of Pretoria, 2010. / Production Animal Studies / unrestricted

Retrogressive thaw slumps are one of the most dramatic thermokarst landforms in periglacial regions. This thesis investigates the impacts of two of the largest hillslope thaw slumps on the geochemistry of periglacial streams on the Peel Plateau, Northwest Territories. It aims to describe the inorganic geochemistry of runoff across active mega-slumps, impacted and pristine tundra streams, as well as that of the ice-rich permafrost exposed in the slump headwalls. Slump runoff is characterized by elevated suspended sediments (911 g/L), high conductivity (2700 µS/cm), and high SO42- ( up to 2078 ppm). The runoff originates as a solute-rich meltwater near the slump headwall, and leaches and re-dissolves soluble salts (e.g., gypsum) as it flows along the mudflow. Conductivity increases until the runoff mixes with pristine tundra streams, diluting the slump runoff signal. SO42-/Cl- is used as a tracer to isolate the slump runoff signal in impacted waters, and suggests that the contribution of slump runoff to the Peel River has been increasing since the 1960s.

The Government of Ontario plans to ban the land application of untreated septage; however, most town wastewater treatment plants do not have the capacity to accept septage. A combined reed bed – freezing bed technology has been successfully developed to dewater and treat septage. Lab column studies established that freeze-thaw conditioning can restore drainage in clogged sand drying beds dosed with common biological sludges and that septage can be dosed at 10 cm/week for 2.5-5.0 months before clogging is observed. Pilot studies showed that freezing beds can operate without the need for a cover with the applied sludge effectively melting any snow cover in regions with moderate snowfall. Septage freezing was successfully modelled following an accepted model for ice formation on water bodies while septage thawing was modelled using a regression analysis with initial frozen depth and precipitation found to be insignificant and degree days of warming controlling the rate of thawing. Model results were utilized to produce a freezing bed design loading map for North America based on temperature normals. Field scale planted and unplanted reed bed – freezing bed systems were constructed and tested with varying hydraulic loading rates (1.9-5.9 m/y) and solid loading rates (43-144 kg/m2/y) over a 5 year period resulting in a recommended design hydraulic loading rate of 2.9 m/y or 75 kg/m2/y. Drainage rates doubled after freeze-thaw conditioning compared to during the growing season, suggesting that freeze-thaw conditioning restores filter hydraulic conductivity. No effect of solid loading rate, planted versus unplanted filters and 7 versus 21 d dosing cycles on filter drainage was observed; however, drainage varied significantly with hydraulic loading rate. The filters separated almost all contaminants with filtrate equivalent to a low-strength domestic wastewater which can be easily treated in any municipal or decentralized wastewater system. The dewatered sludge cake had similar nutrient and solid content to a solid dairy manure and met biosolid land application standards in terms of metals and pathogens. The combined reed bed-freezing bed technology can provide a low-cost solution for the treatment and reuse of septage in cold-climate regions.