Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed April 26, 2007). PDF text: v, 109 p. : ill. UMI publication number: AAT 3229553. Includes bibliographical references. Also available in microfilm and microfiche formats.

Bibliography: leaves 151-172.

Greater demands are being placed on the separable connector to perform with higher reliability in harsher automotive environments. Corrosion in its various forms is a major mechanism which affects contact reliability and this current work focuses on surface oxidation and the related phenomenon of fretting corrosion, from which hot dipped tin (HDT), a common automotive connector coating, is known to suffer. For an in-depth study of high contact resistance, in both static conditions and when subjected to relative micromovement, an interdisciplinary approach was necessary, drawing on the results of published work carried out in the fields of contact and surface science, corrosion and tribology.

abstract: ABSTRACT The purpose of this study was to determine the energy cost of four modes of resistance training (push-ups, pull-ups, curl-ups, lunges). Twelve well trained men aged 23.6 (SD=2.84) years were recruited to participate in the study. Each of the 12 men completed three trials of each of the four exercises on one visit to the laboratory lasting slightly over one hour (M=72 min, SD=5.9 min). The oxygen consumption of the men was monitored constantly throughout the trial and data was recorded every five seconds. Mean VO2 values were calculated for each exercise. The values for push-ups (M=11.57 ml/kg/min, SD=1.99), curl-ups (M=10.99 ml/kg/min, SD=1.48), pull-ups (M=10.87 ml/kg/min, SD=2.51), and lunges (M=14.18 ml/kg/min, SD=1.78) were converted to METs (Metabolic Equivalents). The MET values (3.31, 3.14, 3.11, and 4.05 respectively) all fall within the range of moderate intensity activity. The findings of this study show that a single set of any of the above exercises will qualify as a moderate intensity activity and can be used to meet recommendations on daily physical activity. / Dissertation/Thesis / M.S. Exercise and Wellness 2011

The work in this thesis examines the suitability of utilising ground waste brick as a cement replacement material. The brick types investigated were obtained from the UK,Denmark, Lithuania and Poland. Cement was partially replaced by various quantities and types of ground brick in mortar and concrete. Compressive strength, pore size distribution and sorptivity of mortar generally all benefit from the presence of ground brick and the greatest effect can be seen after water curing for one year. Compressive strength of concrete is also shown to increase as the fineness of ground brick increases although the optimum particle size for ground brick in concrete is still to be determined. The ground bricks investigated have a significant effect on the performance of ground brick mortar when exposed to sodium sulphate solution and synthetic seawater. It is seen that depending on the chemical and phase composition, the effect of ground brick can increase substantially the rate of deterioration of mortar or can reduce significantly the expansion observed. No definite mechanism was identified as being responsible for the observed deterioration of mortar exposed to sodium sulphate solution although it seems likely that water intake due to ettringite formation and adsorption of water by the resultant colloidal product are the primary causes of expansion. Sulphate content, glass content and oxide chemistry of brick are key factors as to its performance when used as a cement replacement material in mortar. Bricks with a high proportion of low calcium glass make very effective pozzolans. Bricks with high calcium glass or a low proportion of glass should not be used as pozzolans. Small amounts of sulphate in ground brick do not have any serious deleterious effects on ground brick mortars and can be beneficial. It is established that it is technically feasible to partially replace cement with ground brick in mortar and concrete, depending on its chemical and phase composition to produce a more durable, cost effective and (due to the lower cement content) a less environmentally damaging material than that produced without cement replacement.

This thesis questions how theatre can act as a site of resistance against the political structures of madness. It analyzes a variety of plays from the past 25 years of British and Irish theatre in order to discern what modes of resistance are possible, and the conceptual lines upon which they follow. It questions how these modes of resistance are imbibed in the representation of madness. It discerns what way these modes relate specifically to the theatrical, and what it is the theatrical specifically has to offer these conceptualizations. It achieves this through a close textual and performative analysis of the selected plays, interrogating these plays from various theoretical perspectives. It follows and explores different conceptualizations across both political and ethical lay lines, looking at what composes the theatrical practical critique, how theatre can alter and play with space, how theatre capacitate the act of witnessing, and the possibility of re-invigorating the ethical encounter through theatrical means. It achieves this through a critical engagement with thinkers such as Michel Foucault, Henri Lefebvre, Jacques Derrida and Emmanuel Levinas. Engaging with the heterogeneity of madness, it covers a variety of madness’s different attributes and logics, including: the constitution and institutional structures of the contemporary asylum; the cultural idioms behind hallucination; the means by which suicide is apprehended and approached; how testimony of the mad person is interpreted and encountered.

To combat the ever-growing clinical burden imposed by antibiotic-resistant pathogens, multiple-antibiotic treatments are increasingly being considered as promising treatment options. The impact of multiple-antibiotic treatments on the evolution of resistance is not well understood however, and debate is ongoing about the effectiveness of various multiple-antibiotic treatments. In this thesis, I investigate how aspects of multiple-antibiotic treatments impact the rate of evolution of antibiotic resistance in the opportunistic human pathogen Pseudomonas aeruginosa. In particular, I look at the impact of interactions between antibiotics in combination on the evolution of resistance, and how creating heterogeneity in the antibiotic environment by rotating the antibiotics used may change the rate of evolution of resistance. I characterise the interactions present in 120 combinations of antibiotics and find that the type of interaction can be predicted by the mechanism of action of the antibiotics involved. I investigate the effect of a subset of these combinations on the evolution of antibiotic resistance. My results refute the influential but poorly-evidenced hypothesis that synergistic combinations accelerate the evolution of resistance, even when synergistic combinations have the same inhibitory effect on sensitive bacteria as additive or antagonistic antibiotic combinations. I focus on a combination of the antibiotics ceftriaxone and sulfamethoxazole and test whether it is more effective in preventing the evolution of resistance than predicted by the inhibitory effect of the combination on sensitive bacteria. I do not find the combination to be more effective than predicted. Finally, I create heterogeneous antibiotic environments by rotating the antibiotic present at different rates. For the first time in a laboratory setting, I test how varying the rate of fluctuation in the antibiotics present in a heterogeneous antibiotic environment impacts the rate of evolution of resistance. Unexpectedly, I find the rate of evolution of resistance increases with increasing levels of antibiotic heterogeneity.

As the acreage of glyphosate-resistant (GR) cropping systems increases, so does the occurrence of herbicide-resistant weeds in the landscape. Biotypes of GR Conyza canadensis were first observed in Delaware, USA, in 2000. Since the first documentation of GR C. canadensis, there have been many instances of independent evolution of GR C. canadensis biotypes. The ecology of GR C. canadensis and any potential fitness consequences of GR trait are still unknown. If there is no fitness cost or a fitness increase associated with the GR trait, GR C. canadensis may increase in prevalence in the landscape even in the absence of glyphosate application. With the consideration that fitness is a difficult parameter to measure, other variables may be used as surrogate measures of fitness, such as reproduction, growth rate, phenology, survivorship, etc. This research seeks to determine if differences exist in surrogate measures of fitness - patterns of growth, reproductive allocation, and competitive ability - and if so, how differences may apply to future population changes, for glyphosate-resistant and -susceptible C. canadensis. The first two experiments presented test two populations of GR plants and two populations of GS plants, first in a greenhouse study of shading effects and intraspecific competition (Chapter 2), and second in a field survivorship study within two habitat types (Chapter 3). The third study tests for the prevalence of GR C. canadensis in field margins of GR cropping systems and seeks correlations in the occurrence of resistance and factors related to geography and field management (Chapter 4). The greenhouse study (Experiment 1, Chapter 2) of surrogate measures of fitness (growth, reproduction) in response to intraspecific competitive ability and shading showed that, while all populations had the same response to shading, there were differences between populations in growth and reproduction. While all measures were greater for individual plants with no competition, plants competing with individuals from one of the GR populations (R2) often had measures that were not different from the no competition treatment or were greater than the other competition treatments (R1, S1, and S2). The field survivorship study compared growth, survival, and reproduction of the previously studied four populations of C. canadensis is two habitats, a old-field in the second year of succession (ruderal) and a soybean field planted with a GR cultivar (agrestal) (Experiment 2, Chapter 3). One of the GR populations (R1) had the highest survivorship of the four populations in the ruderal habitat, while there was no difference in survivorship of the four populations in the agrestal habitat. While there was little difference in growth between ruderal populations, in the agrestal habitat, one GS population (S1) consistently had the smallest diameter, height, and leaf number. One of the agrestal GR populations (R2) was larger than the others, though not always different from R1. R1 was the first population to senesce regardless of habitat. Both agrestal GR populations produced more capitulae (seed heads) than the GS populations, and R1 also showed high reproductive success in the ruderal habitat. A test for the occurrence of GR C. canadensis in field margins of GR cropping systems (Experiment 3, Chapter 4) utilized a discriminating spray test on seed collected from the margins of 17 agricultural fields in 2008 from Illinois, Indiana, and Nebraska. The relationships between the occurrence of GR C. canadensis in 2008 field margins and 1) geography, 2) field management practices, 3) herbicide diversity, 4) weed community diversity, 5) field-interior changes in C. canadensis populations (λ), and 6) knowledge or suspicion of difficult-to-control C. canadensis populations, were tested. Geography was the clearest relationship in these data and was related to geography, with greater, more variable occurrence of GR C. canadensis in 2008 field margins in the southern and eastern sites than the northern and western sites. Management practices in field-interiors from year 2006 to 2008 had little relationship to occurrence of GR C. canadensis in 2008 field margins, except for the increased use of tillage and the increased use of non-glyphosate herbicide modes of action in 2007 field-interiors of fields with the highest occurrence of GR C. canadensis in the field margins in 2008. Additionally, the greatest occurrence of GR C. canadensis was associated with high diversity in the weed community in 2007 field-interiors. These results suggest that GR C. canadensis persisted in 2008 field margins even though there was a perceivable increase in management intensity the previous year. In conclusion, although there were no differences in fitness clearly associated with the GR trait in C. canadensis, GR populations may possess equal or greater vigor in growth, reproduction, and competition as GS populations. Based on these results, GR C. canadensis may persist in agricultural field-margins or other ruderal, unmanaged habitats and act as a seed source for future field-interior infestations. Depending on the characteristics of the GR biotype, GR C. canadensis may increase in frequency in the landscape.

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Made available in DSpace on 2014-06-11T19:32:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-25Bitstream added on 2014-06-13T19:03:30Z : No. of bitstreams: 1 sampaio_nas_dr_guara.pdf: 3261856 bytes, checksum: 1cec5dd1be792fc77fe196fcf0103c70 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As ligas Ni-Cr-Mo têm sido usadas como próteses dentárias por possuírem boa resistência mecânica, elevada resistência à corrosão e também por serem economicamente viáveis. A proteção contra a corrosão destas ligas em soluções salinas típicas de meios fisiológicos é devida ao fenômeno de passivação com a formação de uma camada superficial de óxidos, principalmente óxidos de cromo. Este filme protetor submetido a esforços mecânicos num ambiente corrosivo pode se romper parcialmente liberando íons que apresentam efeitos deletérios no corpo humano. Íons fluoreto existentes em produtos de higiene modificam o ambiente bucal e sua presença pode possibilitar o início de um processo corrosivo localizado. O objetivo deste trabalho foi estudar a resistência à corrosão de três ligas de Ni-Cr-Mo, de diferentes composições: SC (73% Ni; 14%Cr; 8,5%Mo; 1,8% Be; 1,8%Al), SB (61%Ni; 25%Cr; 10,5%Mo; 1,5%Si) e W (65%Ni; 22,5%Cr; 9,5%Mo; 1,0% Nb; 1,0% Si; 0,5%Fe) em meios contendo fluoretos que simulam as soluções de enxágue bucal. O estudo foi realizado em solução de NaF 0,05 %, NaCl 0,05 % e colutórios comerciais em pH 6,0 a 37ºC, utilizando análise metalográfica, técnica de imersão e ensaios eletroquímicos, . A liga SC, com o maior teor de níquel e o menor teor de cromo não se passiva nos meios estudados apresentando um aumento contínuo na densidade de corrente em função do aumento do potencial, enquanto que as outras ligas apresentam intervalo de passivação de 600 mV e densidade de corrente passiva 10-6 A / cm2. De um modo geral, considerando os ensaios de corrosão por imersão e eletroquímicos, conclui-se que o pior desempenho foi atribuído à liga SC, enquanto que, W e SB apresentaram os melhores desempenhos e comportamentos bastante similares. / Ni-Cr-Mo alloys have been used as dental prostheses due their properties such as good mechanical strength, high corrosion resistance and also because they are economically viable. These alloys corrosion protection in salt solutions which are typical of physiological media, is due to the phenomenon called passivation with an oxide superficial layer formation, particularly chromium oxides. This protective film, subjected to mechanical stress in a corrosive environment,can be broken partially releasing ions that have deleterious effects in a human body. Fluoride ions, existent in hygiene products, change the oral environment and their presence may enable the beginning of a localized corrosion process. The objectics this work is to evaluate the corrosion resistance of three Ni-Cr-Mo alloys, of different compositions: SC (73% Ni, 14% Cr, 8.5% Mo, 1.8% Be, 1.8% Al) SB (61% Ni, 25% Cr, 10.5% Mo, 1.5% Si) and W (65% Ni, 22.5% Cr, 9.5% Mo, 1.0% Nb, 1.0% Si, 0.5% Fe) in media containing fluoride which simulate oral rinse solutions. This study has been in solution of 0.05% NaF, NaCl 0.05% and commercial mouthwashes on pH 6.0 at 37 ° C using metallography analyses, immersion techniques, and electrochemical tests, impedance tests and analysis. SC, with the highest nickel and the lowest chromium content, does not passivate in the studied means showing a continuous increase in current density due to increasing potential, while the other alloys exhibit passivation range of 600 mV and passive current density 10-6 A / cm2. In general, considering the immersion and electrochemical corrosion tests, it is concluded that the worst performance has been attributed to the alloy SC, while W and SB have shown the best performance and very similar behaviors.