Genetically modified (GM) canola (Brassica napus L.) has been widely adopted in Canada since its commercial release in 1995 and now represents over 85% of the canola grown in western Canada. Concurrently, GM canola volunteers have become an increasing management problem in cultivated fields and are ubiquitous in adjacent ruderal (non-cropped disturbed) habitats. However, systematic post-release monitoring is lacking and the ecological and agronomic impacts of escaped GM canola are poorly understood. In this dissertation, I characterize the escape, demography and distribution of GM canola in ruderal habitats in southern Manitoba, at multiple spatial and temporal scales. I characterized GM herbicide tolerance traits in 16 escaped canola populations. The progeny of 129 plants were tested in herbicide trials; 74% of plants produced glyphosate-tolerant progeny, 63% produced glufosinate-tolerant progeny, and 34% produced multiple herbicide-tolerant progeny as a result of gene flow between escaped plants. At the population-scale, four escaped GM canola populations were monitored and periodic matrix models were constructed to describe the dynamics and persistence of flowering plants. Escaped populations were observed to flower in synchrony with adjacent crops and were projected to persist for 2 to 5 years, confirming the potential for gene flow between escaped and cultivated canola populations. At the landscape-scale, the distribution of escaped canola was surveyed in three agricultural regions. Regional factors were important determinants of distribution; escaped canola density was positively correlated with canola cropping intensity and with traffic intensity, and was negatively correlated with distance to grain distribution centres. Local seed dispersal had negligible impact on distribution compared to landscape-scale anthropogenic seed inputs resulting from agricultural transport. These findings suggest that escaped canola persists as a metapopulation, where long-distance dispersal and colonization compensate for frequent extinction of local populations. Escaped populations play an important role in the persistence and spread of GM traits at large spatial scales, with substantial implications for the coexistence of GM and non-GM crops, and especially for organic and reduced-tillage farming operations. Landscape-scale management approaches, designed and implemented collaboratively by multiple stakeholders, are necessary to mitigate the risks of contamination resulting from GM trait escape. Regulation and ongoing monitoring of GM crops must acknowledge and address the dynamic regional nature of seed- and pollen-mediated gene flow.

Several pathogenic bacteria, including Listeria monocytogenes, use an F-actin-dependent motility process to spread between mammalian cells. Actin ‘comet tails’ propel Lm through the cytoplasm, resulting in bacteria-containing membrane protrusions that are internalized by neighboring cells. The mechanism by which L. monocytogenes overcomes cortical membrane tension to generate protrusions is unknown. In this work, I identify bacterial and host proteins that directly regulate the formation of protrusions. First, I show that efficient cell-cell spread in polarized epithelial cells requires the secreted Lm virulence protein, InlC. I next identify the mammalian adaptor protein Tuba as a ligand of InlC. InlC binds to a C-terminal SH3 domain in Tuba, which normally engages the human actin regulatory protein N-WASP. InlC promotes protrusion formation by inhibiting Tuba and N-WASP function, most likely by impairing binding of N-WASP to the Tuba SH3 domain. Tuba and N-WASP are known to control the structure of apical junctions in epithelial cells [1]. I demonstrate that, by inhibiting Tuba and N-WASP, InlC transforms taut apical cell-cell junctions into structures with a “slack” morphology. Experiments with Myosin II inhibitors indicate that InlC-mediated perturbation of cell junctions accounts for the role of this bacterial protein in protrusion formation. Collectively, my results suggest that InlC enhances bacterial dissemination by relieving cortical tension in apical junctions, thereby enhancing the ability of motile bacteria to deform the plasma membrane into protrusions to allow their spread into neighbouring cells.

No description available.

Despite habitat perturbations and seasonal fluctuations in reproduction, many studies report no significant inter-annual variation in Great Egret reproductive performance. I examined the reproductive performance of Great Egrets (Ardea alba) for two breeding seasons (2009 and 2010) immediately following Hurricane Ike at High Island, Texas. Breeding success, productivity, and mean brood size did not differ between years (U-test, P > 0.05). Fledging success at 21 days showed no significant difference between years, however fledging success at 28, 35, and 42 days decreased significantly between years (~15% reduction at 42 days; U-test, P = 0.027). The number of deaths per nest also differed significantly between 2009 and 2010 (0.36 and 0.95, respectively) (U-test, P = 0.013). Brood-size dependent mortality was also a significant between-year parameter (H test, P = 0.003). Successful nests in 2009 had a brood size range of 2 to 3, and of these nests, 6% and 50% experienced partial brood reduction, respectively; whereas 2010 brood size range for successful nests was 2 to 4, and 0%, 57%, and 100% of these nests, respectively, experienced partial brood reduction. Other parameters examined were water level, temperature, precipitation, prey availability, and human disturbance. I rejected my hypothesis that habitat conditions would be less conducive to high reproductive success in 2009 than 2010, due to the impacts of Hurricane Ike. My results suggest that Great Egrets have bimodal occurrences of nestling death that are expressed as a function of brood size, hatching spread, and nestling age. Reproductive performance studies should continue through at least fledging age (42 days post-hatching for Great Egrets) to better document the reproductive performance, especially by incorporating the apparent behavioral plasticity of nestlings.

This study addressed the use of benefit levers to develop a guide for an operational plan for spread of best practices in the health system of South Africa. Using the best evidence to inform practice is the cornerstone of quality patient care. Besides uptake and implementation, spreading best practices is crucial as this provides more patients with evidence-informed care and to improve practice and health (care) outcomes. However, spread of best practices is not always effectively done. An example includes Kangaroo Mother Care (KMC) as this best practice is translated for practice and implemented on a limited scale; spread to the whole system seems to be problematic. Various factors can be used to facilitate the spread of best practices. Edwards and Grinspun identified four benefit levers which create the tipping point towards successful adoption, implementation and spread of evidence: alignment, permeation plans, leadership for change, and supporting and reinforcing structures. However, little is known about these benefit levers and it remains unclear what the use of benefit levers for system-wide spread would entail, specifically for other contexts as the model (including the benefit levers) has never been operationalised (Edwards & Grinspun, 2011:19). The overall aim of this study entails therefore the development of a guide for an operational plan, formulating the use of benefit levers in the spread of best practices. To achieve this aim the following objectives for this study were set: 1. To explore and describe characteristics of benefit levers to facilitate spread of best practices. 2. To develop a guide for an operational plan to use benefit levers for the spread of best practices. This study was embedded in the postmodern paradigm, whereby the systems theory was used as a theoretical framework. The first objective was achieved by two steps. Firstly, an integrative literature review of concept clarification of the four benefit levers was done. Secondly, semi-structured individual interviews were conducted with key informants from a variety of levels of the health system involved in the spread of KMC in South Africa. Findings were used to achieve objective two. A draft guide for an operational plan was developed, based on the findings of the individual interviews. A logic model was used as format. This guide was refined by experts using the Delphi technique. The Delphi involved two rounds. From the feedback of the first round of the Delphi, a logic model which provides a graphic outlook of the guide, was suggested and refined in the second round, together with the guide. Further, after the Delphi, a template useable for practice was derived from the guide. The guide, logic model and template could help organisations or departments planning to spread best practices in a certain context (e.g. South Africa), to develop an operational plan, where these benefit levers are considered. This is crucial as currently best practices (such as Kangaroo Mother Care) are often not spread on a system-wide basis to improve practice. The guide will therefore be made accessible to health care workers and researchers in South Africa Finally, conclusions were drawn, the research was evaluated, limitations were identified and recommendations were formulated for nursing practice, education and research. Overall, it can be concluded that for effective spread of best practices the benefit levers alignment, permeation plans, leadership for change and supporting and reinforcing structures are required. Further, specifically regarding the objectives and steps of this study the following conclusions can be made: • Literature/studies about leadership for change and supporting and reinforcing structures was found, but regarding alignment and permeation plans, limited rigorous literature was found (Objective 1 – Step 1). • Key informants involved in the spread of a specific best practice (Kangaroo Mother Care) could see the value of benefit levers used for the spread of best practices in the South African health system (Objective 1 – Step 2). • Benefit levers were found useful for development of a guide for an operational plan to spread best practices. This guide will be made accessible to be used by healthcare organisations and departments in South Africa (Objective 2 – Steps 1 and 2). / Thesis (PhD (Nursing))--North-West University, Potchefstroom Campus, 2013

This study addressed the use of benefit levers to develop a guide for an operational plan for spread of best practices in the health system of South Africa. Using the best evidence to inform practice is the cornerstone of quality patient care. Besides uptake and implementation, spreading best practices is crucial as this provides more patients with evidence-informed care and to improve practice and health (care) outcomes. However, spread of best practices is not always effectively done. An example includes Kangaroo Mother Care (KMC) as this best practice is translated for practice and implemented on a limited scale; spread to the whole system seems to be problematic. Various factors can be used to facilitate the spread of best practices. Edwards and Grinspun identified four benefit levers which create the tipping point towards successful adoption, implementation and spread of evidence: alignment, permeation plans, leadership for change, and supporting and reinforcing structures. However, little is known about these benefit levers and it remains unclear what the use of benefit levers for system-wide spread would entail, specifically for other contexts as the model (including the benefit levers) has never been operationalised (Edwards & Grinspun, 2011:19). The overall aim of this study entails therefore the development of a guide for an operational plan, formulating the use of benefit levers in the spread of best practices. To achieve this aim the following objectives for this study were set: 1. To explore and describe characteristics of benefit levers to facilitate spread of best practices. 2. To develop a guide for an operational plan to use benefit levers for the spread of best practices. This study was embedded in the postmodern paradigm, whereby the systems theory was used as a theoretical framework. The first objective was achieved by two steps. Firstly, an integrative literature review of concept clarification of the four benefit levers was done. Secondly, semi-structured individual interviews were conducted with key informants from a variety of levels of the health system involved in the spread of KMC in South Africa. Findings were used to achieve objective two. A draft guide for an operational plan was developed, based on the findings of the individual interviews. A logic model was used as format. This guide was refined by experts using the Delphi technique. The Delphi involved two rounds. From the feedback of the first round of the Delphi, a logic model which provides a graphic outlook of the guide, was suggested and refined in the second round, together with the guide. Further, after the Delphi, a template useable for practice was derived from the guide. The guide, logic model and template could help organisations or departments planning to spread best practices in a certain context (e.g. South Africa), to develop an operational plan, where these benefit levers are considered. This is crucial as currently best practices (such as Kangaroo Mother Care) are often not spread on a system-wide basis to improve practice. The guide will therefore be made accessible to health care workers and researchers in South Africa Finally, conclusions were drawn, the research was evaluated, limitations were identified and recommendations were formulated for nursing practice, education and research. Overall, it can be concluded that for effective spread of best practices the benefit levers alignment, permeation plans, leadership for change and supporting and reinforcing structures are required. Further, specifically regarding the objectives and steps of this study the following conclusions can be made: • Literature/studies about leadership for change and supporting and reinforcing structures was found, but regarding alignment and permeation plans, limited rigorous literature was found (Objective 1 – Step 1). • Key informants involved in the spread of a specific best practice (Kangaroo Mother Care) could see the value of benefit levers used for the spread of best practices in the South African health system (Objective 1 – Step 2). • Benefit levers were found useful for development of a guide for an operational plan to spread best practices. This guide will be made accessible to be used by healthcare organisations and departments in South Africa (Objective 2 – Steps 1 and 2). / Thesis (PhD (Nursing))--North-West University, Potchefstroom Campus, 2013

No description available.

No description available.

Genetically modified (GM) canola (Brassica napus L.) has been widely adopted in Canada since its commercial release in 1995 and now represents over 85% of the canola grown in western Canada. Concurrently, GM canola volunteers have become an increasing management problem in cultivated fields and are ubiquitous in adjacent ruderal (non-cropped disturbed) habitats. However, systematic post-release monitoring is lacking and the ecological and agronomic impacts of escaped GM canola are poorly understood. In this dissertation, I characterize the escape, demography and distribution of GM canola in ruderal habitats in southern Manitoba, at multiple spatial and temporal scales. I characterized GM herbicide tolerance traits in 16 escaped canola populations. The progeny of 129 plants were tested in herbicide trials; 74% of plants produced glyphosate-tolerant progeny, 63% produced glufosinate-tolerant progeny, and 34% produced multiple herbicide-tolerant progeny as a result of gene flow between escaped plants. At the population-scale, four escaped GM canola populations were monitored and periodic matrix models were constructed to describe the dynamics and persistence of flowering plants. Escaped populations were observed to flower in synchrony with adjacent crops and were projected to persist for 2 to 5 years, confirming the potential for gene flow between escaped and cultivated canola populations. At the landscape-scale, the distribution of escaped canola was surveyed in three agricultural regions. Regional factors were important determinants of distribution; escaped canola density was positively correlated with canola cropping intensity and with traffic intensity, and was negatively correlated with distance to grain distribution centres. Local seed dispersal had negligible impact on distribution compared to landscape-scale anthropogenic seed inputs resulting from agricultural transport. These findings suggest that escaped canola persists as a metapopulation, where long-distance dispersal and colonization compensate for frequent extinction of local populations. Escaped populations play an important role in the persistence and spread of GM traits at large spatial scales, with substantial implications for the coexistence of GM and non-GM crops, and especially for organic and reduced-tillage farming operations. Landscape-scale management approaches, designed and implemented collaboratively by multiple stakeholders, are necessary to mitigate the risks of contamination resulting from GM trait escape. Regulation and ongoing monitoring of GM crops must acknowledge and address the dynamic regional nature of seed- and pollen-mediated gene flow.

With the increasing demand for more wireless multimedia applications, it is desired to design a wireless system with higher data rate. Furthermore, the frequency spectrum has become a limited and valuable resource, making it necessary to utilize the available spectrum efficiently and coexist with other wireless systems. Orthogonal frequency division multiplexing (OFDM) modulation is widely used in communication systems to meet the demand for ever increasing data rates. The major advantage of OFDM over single-carrier transmission is its ability to deal with severe channel conditions without complex equalization. However, OFDM systems suffer from a high peak to average power ratio, and they are sensitive to carrier frequency offset and Doppler spread. This dissertation first focuses on the development of intercarrier interference (ICI) reduction and signal detection algorithms for OFDM systems over time-varying channels. Several ICI reduction algorithms are proposed for OFDM systems over doubly-selective channels. The OFDM ICI reduction problem over time-varying channels is formulated as a combinatorial optimization problem based on the maximum likelihood (ML) criterion. First, two relaxation methods are utilized to convert the ICI reduction problem into convex quadratic programming (QP) problems. Next, a low complexity ICI reduction algorithm applicable to $M$-QAM signal constellations for OFDM systems is proposed. This formulates the ICI reduction problem as a QP problem with non-convex constraints. A successive method is then utilized to deduce a sequence of reduced-size QP problems. For the proposed algorithms, the QP problems are solved by limiting the search in the 2-dimensional subspace spanned by its steepest-descent and Newton directions to reduce the computational complexity. Furthermore, a low-bit descent search (LBDS) is employed to improve the system performance. Performance results are given to demonstrate that the proposed ICI reduction algorithms provide excellent performance with reasonable computational complexity. A low complexity joint semiblind detection algorithm based on the channel correlation and noise variance is proposed which does not require channel state information. The detection problem is relaxed to a continuous non-convex quadratic programming problem. Then an iterative method is utilized to deduce a sequence of reduced-size quadratic programming problems. A LBDS method is also employed to improve the solution of the derived QP problems. Results are given which demonstrate that the proposed algorithm provides similar performance with lower computational complexity compared to that of a sphere decoder. A major challenge to OFDM systems is how to obtain accurate channel state information for coherent detection of the transmitted signals. Thus several channel estimation algorithms are proposed for OFDM systems over time-invariant channels. A channel estimation method is developed to utilize the noncircularity of the input signals to obtain an estimate of the channel coefficients. It takes advantage of the nonzero cyclostationary statistics of the transmitted signals, which in turn allows blind polynomial channel estimation using second-order statistics of the OFDM symbol. A set of polynomial equations are formulated based on the correlation of the received signal which can be used to obtain an estimate of the time domain channel coefficients. Performance results are presented which show that the proposed algorithm provides better performance than the least minimum mean-square error (LMMSE) algorithm at high signal to noise ratios (SNRs), with low computational complexity. Near-optimal performance can be achieved with large OFDM systems. Finally, a CS-based time-domain channel estimation method is presented for OFDM systems over sparse channels. The channel estimation problem under consideration is formulated as a small-scale $l_1$-minimization problem which is convex and admits fast and reliable solvers for the globally optimal solution. It is demonstrated that the magnitudes as well as delays of the significant taps of a sparse channel model can be estimated with satisfactory accuracy by using fewer pilot tones than the channel length. Moreover, it is shown that a fast Fourier transform (FFT) matrix of extended size can be used as a set of appropriate basis vectors to enhance the channel sparsity. This technique allows the proposed method to be applicable to less-sparse OFDM channels. In addition, a total-variation (TV) minimization based method is introduced to provide an alternative way to solve the original sparse channel estimation problem. The performance of the proposed method is compared to several established channel estimation algorithms. / Graduate