• I must walk through the gate : an ontological necessity

      Brown, Hilary; Department of Graduate and Undergraduate Studies in Education (Brock University, 2010-10-26)
      This research is a self-study into my life as an athlete, elementary school teacher, leamer, and as a teacher educator/academic. Throughout the inquiry, I explore how my beliefs and values infused my lived experiences and ultimately influenced my constructivist, humanist, and ultimately my holistic teaching and learning practice which at times disrupted the status quo. I have written a collection of narratives (data generation) which embodied my identity as an unintelligent student/leamer, a teacher/learner, an experiential learner, a tenacious participant, and a change agent to name a few. As I unpack my stories and hermeneutically reconstruct their intent, I question their meaning as I explore how I can improve my teaching and learning practice and potentially effect positive change when instructing beginning teacher candidates at a Faculty of Education. At the outset I situate my story and provide the necessary political, social, and cultural background information to ground my research. I follow this with an in depth look at the elements that interconnect the theoretical framework of this self-study by presenting the notion of writing at the boundaries through auto ethnography (Ellis, 2000; Ellis & Bochner, 2004) and writing as a method of inquiry (Richardson, 2000). The emergent themes of experiential learning, identity, and embodied knowing surfaced during the data generation phase. I use the Probyn' s (1990) .. metaphor of locatedness to unpack these themes and ponder the question, Where is experience located? I deepen the exploration by layering Drake's (2007) KnowlDo/Be framework alongside locatedness and offer descriptions of learning moments grounded in pedagogical theories. In the final phase, I introduce thirdspace theory (Bhabha, 1994; Soja, 1996) as a space that allowed me to puzzle educational dilemmas and begin to reconcile the binaries that existed in my life both personally, and professionally. I end where I began by revisiting the questions that drove this study. In addition, Ireflect upon the writing process and the challenges that I encountered while immersed in this approach and contemplate the relevance of conducting a self-study. I leave the reader with what is waiting for me on the other side of the gate, for as Henry James suggested, "Experience is never limited, and it is never complete."
    • Identification and characterization of a Catharanthus roseus mutant altered in monoterpenoid indole alkaloid biosynthesis

      Thamm, Antje MK; Department of Biological Sciences (Brock University, 2014-09-09)
      The Madagascar periwinkle [Catharanthus roseus (L.) G. Don] is a commercially important horticultural flower species and is the only source for several pharmaceutically valuable monoterpenoid indole alkaloids (MIAs), including the powerful antihypertensive ajmalicine and the antineoplastic agents vincristine and vinblastine. While biosynthesis of MIA precursors has been elucidated, conversion of the common MIA precursor strictosidine to MIAs of different families, for example ajmalicine, catharanthine or vindoline, remains uncharacterized. Deglycosylation of strictosidine by the key enzyme Strictosidine beta-glucosidase (SGD) leads to a pool of uncharacterized reaction products that are diverted into the different MIA families, but the downstream reactions are uncharacterized. Screening of 3600 EMS (ethyl methane sulfonate) mutagenized C. roseus plants to identify mutants with altered MIA profiles yielded one plant with high ajmalicine, and low catharanthine and vindoline content. RNA sequencing and comparative bioinformatics of mutant and wildtype plants showed up-regulation of SGD and the transcriptional repressor Zinc finger Catharanthus transcription factor (ZCT1) in the mutant line. The increased SGD activity in mutants seems to yield a larger pool of uncharacterized SGD reaction products that are channeled away from catharanthine and vindoline towards biosynthesis of ajmalicine when compared to the wildtype. Further bioinformatic analyses, and crossings between mutant and wildtype suggest a transcription factor upstream of SGD and ZCT1 to be mutated, leading to up-regulation of Sgd and Zct1. The crossing experiments further show that biosynthesis of the different MIA families is differentially regulated and highly complex. Three new transcription factors were identified by bioinformatics that seem to be involved in the regulation of Zct1 and Sgd expression, leading to the high ajmalicine phenotype. Increased cathenamine reductase activity in the mutant converts the pool of SGD reaction products into ajmalicine and its stereoisomer tetrahydroalstonine. The stereochemistry of ajmalicine and tetrahydroalstonine biosynthesis in vivo and in vitro was further characterized. In addition, a new clade of perakine reductase-like enzymes was identified that reduces the SGD reaction product vallesiachotamine in a stereo-specific manner, characterizing one of the many reactions immediately downstream of SGD that determine the different MIA families. This study establishes that RNA sequencing and comparative bioinformatics, in combination with molecular and biochemical characterization, are valuable tools to determine the genetic basis for mutations that trigger phenotypes, and this approach can also be used for identification of new enzymes and transcription factors.
    • Identification and characterization of retinoic acid-induced morphological and electrophysiological changes in an invertebrate nervous system

      Vesprini, Nicholas; Department of Biological Sciences (Brock University, 2012-07-31)
      The vitamin A metabolite, retinoic acid (RA) is known to play an important role in the development, patterning and regeneration of nervous tissue, both in the embryo and in the adult. Classically, RA is known to mediate the transcription of target genes through the binding and activation ofits nuclear receptors: the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). Recently, mounting evidence from many animal models has implicated a number of RA-mediated effects operating independently of gene transcription, and thus highlights nove~ nongenornic actions of RA. For example, recent work utilizing cultured neurons from the pond snaa Lymnaea stagnalis, has shown that RA can elicit a regenerative response, growth cone turning, independently of "classical" transcriptional activation While this work illustrates a novel regeneration-inducing effect in culture, it is currently -unknown whether RA also induces regeneration in situ. This study has sought to determine RA's regenerative effucts at the morphological and molecular levels by utilizing an in situ approach focusing on a single identified dopaminergic neuron which possesses a known "mapped" morphology within the CNS. These studies show, for the first time in an invertebrate, that RA can increase neurite outgrowth of dopaminergic cells that have undergone a nerve-crush injury. Utilizing Western blot analysis, it was shown that this effect appears to be independent of any changes in whole CNS expression levels of either the RAR or RXR. Additionally, utilizing immunohistochemistry, to examine protein localization, there does not appear to be any obvious changes in the RXR expression level at the crush site. Changes in cell morphology such as neurity extension are known to be modulated by changes in neuronal firing activity. It has been previously shown that exposure to RA over many days can lead to changes in the electrophysiological properties of cultured Lymnaea neurons; however, no studies have investigated whether short-term exposure to RA can elicit electrophysiological changes and/or changes in firing pattern of neurons in Lymnaea or any other species. The studies performed here show, for the first time in any species, that short-tenn treatment with RA can elicit significant changes in the firing properties of both identified dopaminergic neurons and peptidergic neurons. This effect appears to be independent of protein synthesis, activation of protein kinase A or phospholipase C, and calcium influx but is both dose-dependent and isomer-dependent. These studies provide evidence that the RXR, but not RAR, may be involved, and that intracellular calcium concentrations decrease upon RAexposure with a time course, dose-dependency and isomer-dependency that coincide with the RA-induced electrophysiological changes. Taken together, these studies provide important evidence highlighting RA as a multifunctional molecule, inducing morphological, molecular and electrophysiological changes within the CNS, and highlight the many pathways through which RA may operate to elicit its effects.
    • Identification of novel retinoid receptors and their roles in vertebrate and invertebrate nervous systems

      Charter, Christopher J; Department of Biological Sciences (Brock University, 2012-07-30)
      In vertebrates, signaling by retinoic acid (RA) is known to play an important role in embryonic development, as well as organ homeostasis in the adult. In organisms such as adult axolotls and newts, RA is also important for regeneration of the CNS, limb, tail, and many other organ systems. RA mediates many of its effects in development and regeneration through nuclear receptors, known as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). This study provides evidence for an important role of the RA receptor, RAR~2, in ,( '. regeneration ofthe spinal cord and tail of the adult newt. It has previously been proposed that the ability of the nervous system to regenerate might depend on the presence or absence of this RAR~2 isoform. Here, I show for the very first time, that the regenerating spinal cord of the adult newt expresses this ~2 receptor isoform, and inhibition of retinoid signaling through this specific receptor with a selective antagonist inhibits tail and spinal cord regeneration. This provides the first evidence for a role of this receptor in this process. Another species capable of CNS ~~generation in the adult is the invertebrate, " Lymnaea stagnalis. Although RA has been detected in a small number of invertebrates (including Lymnaea), the existence and functional roles of the retinoid receptors in most invertebrate non-chordates, have not been previously studied. It has been widely believed, however, that invertebrate non-chordates only possess the RXR class of retinoid receptors, but not the RARs. In this study, a full-length RXR cDNA has been cloned, which was the first retinoid receptor to be discovered in Lymnaea. I then went on to clone the very first full-length RAR eDNA from any non-chordate, invertebrate species. The functional role of these receptors was examined, and it was shown that normal molluscan development was altered, to varying degrees, by the presence of various RXR and RAR agonists or antagonists. The resulting disruptions in embryogenesis ranged from eye and shell defects, to complete lysis of the early embryo. These studies strongly suggest an important role for both the RXR and RAR in non-chordate development. The molluscan RXR and RAR were also shown to be expressed in the adult, nonregenerating eNS, as well as in individual motor neurons regenerating in culture. More specifically, their expression displayed a non-nuclear distfibution, suggesting a possible non-genomic role for these 'nuclear' receptors. It was shown that immunoreactivity for the RXR was present in almost all regenerating growth cones, and (together with N. Farrar) it was shown that this RXR played a novel, non-genomic role in mediating growth cone turning toward retinoic acid. Immunoreactivity for the novel invertebrate RAR was also found in the regenerating growth cones, but future work will be required to determine its functional role in nerve cell regeneration. Taken together, these data provide evidence for the importance of these novel '. retinoid receptors in development and regeneration, particularly in the adult nervous system, and the conservation of their effects in mediating RA signaling from invertebrates to vertebrates.
    • Identifying language needs of ESL students in a Canadian university based intensive English language program

      Nakaprasit, Thinan; Department of Graduate and Undergraduate Studies in Education (Brock University, 2010-10-25)
      This study investigated the needs of adult ESL learners intending to pursue higher education in Canada. Its chief purpose was to enable educators and administrators to design ESL programs that would prepare students to function at optimal levels in academic and social settings during their university studies. The study adopted a mixed research method that was predominantly qualitative in its orientation and narrative in its implementation. It focused on an Intensive English Language Program (IELP) offered at an Ontario university. Using a holistic approach, the study sought to represent the various perspectives of all the participants in the program: the students, the instructors, and the administrators. Analysis of both qualitative and quantitative data gathered from 17 students, 6 instructors, and 1 administrator in the IELP showed that to a large extent the academic needs ofESL learners in the IELP were generally not being met. Most notably, the study found that learners were not receiving sufficient training in speaking and listening skills, a factor that contributed to their sense of insecurity and lack of confidence in their ability to communicate successfully in academic and social settings. The study also revealed that the solutions to many of the problems it identified lay not in the classroom but in the way the ESL program was structured administratively. One major recommendation to come out of the study is that programs like the IELP should be restructured so as to give them greater flexibility in meeting individual needs. While the study labored under certain limitations and did not achieve all of its goals, it did succeed in creating awareness ofthe problems and in establishing a methodological approach that can serve as a framework within which future research may be conducted in this somewhat neglected area.
    • Impact And Effects Of Learning Outcome-Oriented Program Review Policy Changes in Ontario Universities

      Borin, Paola; Borin, Paola; Department of Graduate and Undergraduate Studies in Education
      This multiple-case, mixed methods study characterized the effects, and outcomes perceived by key participants involved in the program review process at four universities, five years after the introduction of a common learning-outcomes oriented quality assurance review process across the province of Ontario in 2011. Purposeful and criterion sampling was applied to identify key informants from four universities, with specialized knowledge and experience from five levels of involvement in recently conducted cyclical program reviews employing the new framework. This included, faculty members, department chairs, teaching and learning centre support staff, quality assurance support staff, and senior administrators. Data were collected using in-depth interviews comprised of structured and unstructured questions. Analysis applied variable and case oriented strategies, thematic and content analysis, and matrix displays. This research found three orientations to the review influenced perceptions and outcomes, including a standard accountability, control and compliance, and an enhancement orientation. Nearly half the changes participants identified as triggered by the review process are likely to have a long-term impact. Perceived negative changes included increased oversight, bureaucracy, and workload. Objectives and accountability of the cyclical review were confounded with ongoing budgetary reviews, institutional goal setting, and measures of the fiscal sustainability. Perceived positive changes included longer-term effects such as increased alignment of curriculum to student outcomes, increased departmental discussion about curriculum, and more consistent provision of program relevant data across the university. Participants described a shift from a focus on teaching students, to a focus on bringing about learning.
    • Impact of different irrigation strategies on grapes and wine quality of four grapevine cultivars (Vitis sp.) in cool climate conditions. An investigation into the relationships among ABA, water status, grape cultivar and wine quality

      Balint, Gabriel; Department of Biological Sciences (Brock University, 2012-04-04)
      Niagara Peninsula of Ontario is the largest viticultural area in Canada. Although it is considered to be a cool and wet region, in the last decade many water stress events occurred during the growing seasons with negative effects on grape and wine quality. This study was initiated to understand and develop the best strategies for water management in vineyards and those that might contribute to grape maturity advancement. The irrigation trials investigated the impact of time of initiation (fruit set, lag phase and veraison), water replacement level based on theoretical loss through crop evapotranspiration (ETc; 100,50 and 25%) and different irrigation strategies [partial root zone drying (PRD) versus regulated deficit irrigation (RD!)] on grape composition and wine sensory profiles. The irrigation experiments were conducted in a commercial vineyard (Lambert Vineyards Inc.) located in Niagara-on-the-Lake, Ontario, from 2005 through 2009. The two experiments that tested the combination of different water regimes and irrigation time initiation were set up in a randomized block design as follows: Baco noir - three replicates x 10 treatments [(25%, 50% and 100% of ETc) x (initiation at fruit set, lag phase and veraison) + control]; Chardonnay - three replicates x seven treatments [(25%, 50% and 100% of ETc) x (initiation at fruit set and veraison) + control]. The experiments that tested different irrigation strategies were set up on two cultivars as follows: Sauvignon blanc - four replicates x four treatments [control, fully irrigated (100% ETc), PRD (100% ETc) and RDI (25% ETc)]; Cabemet Sauvignon - four replicates x five treatments [control, fully irrigated (100% ETc), PRD (100% ETc), RDI (50% ETc) and RDI (25% ETc)]. The controls in each experiment were nonirrigated. The irrigation treatments were compared for many variables related to soil water status, vine physiology, berry composition, wine sensory profile, and hormone composition [(abscisic acid (ABA) and its catabolites]. Soil moisture profile was mostly affected by irrigation treatments between 20 and 60 em depth depending on the grapevine cultivar and the regime of water applied. Overall soil moisture was consistently higher throughout the season in 100 and 50% ETc compare to the control. Transpiration rates and leaf temperature as well as shoot growth rate were the most sensitive variables to soil water status. Drip irrigation associated with RDI treatments (50% ETc and 25% ETc) had the most beneficial effects on vine physiology, fruit composition and wine varietal typicity, mainly by maintaining a balance between vegetative and reproductive parts of the vine. Neither the control nor the 100 ETc had overall a positive effect on grape composition and wine sensory typicity. The time of irrigation initiation affected the vine physiology and grape quality, the most positive effect was found in treatments initiated at lag phase and veraison. RDI treatments were overall more consistent in their positive effect on grape composition and wine varietal typicity comparing to PRD treatment. The greatest difference between non-irrigated and irrigated vines in most of the variables studied was found in 2007, the driest and hottest season of the experimental period. Soil water status had a greater and more consistent effect on red grapevine cultivars rather than on white winegrape cultivars. To understand the relationships among soil and plant water status, plant physiology and the hormonal profiles associated with it, abscisic acid (ABA) and its catabolites [phaseic acid (PA), dihydrophaseic acid (DPA), 7-hydroxy-ABA (TOH-ABA), 8' -hydroxy-ABA, neophaseic acid and abscisic acid glucose ester (ABA-GE)] were analyzed in leaves and berries from the Baco noir and Chardonnay irrigation trials over two growing seasons. ABA and some of its catabolites accurately described the water status in the vines. Endogenous ABA and some of its catabolites were strongly affected in Baco noir and Chardonnay by both the water regime (i.e. ET level) and timing of irrigation initiation. Chardonnay grapevines produced less ABA in both leaves and berries compared to Baco noir, which indicated that ABA synthesis is also cultivar dependant. ABA-GE was the main catabolite in treatments with high water deficits, while PA and DPA were higher in treatments with high water status, suggesting that the vine produced more ABA-GE under water deficits to maintain rapid control of the stomata. These differences between irrigation treatments with respect to ABA and catabolites were particularly noticeable in the dry 2007 season. Two trials using exogenous ABA investigated the effect of different concentrations of ABA and organs targeted for spraying, on grape maturation and berry composition of Cabemet Sauvignon grapevines, in two cool and wet seasons (2008-2009). The fIrst experiment consisted of three replicates x three treatments [(150 and 300 mg/L, both applications only on clusters) + untreated control] while the second experiment consisted in three replicates x four treatments [(full canopy, only clusters, and only leaves sprayed with 300 ppm ABA) + untreated control]. Exogenous ABA was effective in hastening veraison, and improving the composition of Cabemet Sauvignon. Ability of ABA to control the timing of grape berry maturation was dependant on both solution concentration and the target organ. ABA affected not only fruit composition but also yield components. Berries treated with ABA had lower weight and higher skin dry mass, which constitutes qualitative aspects desired in the wine grapes. Temporal advancement of ripening through hormonal control can lead to earlier fruit maturation, which is a distinct advantage in cooler areas or areas with a high risk of early frost occurrence. Exogenous ABA could provide considerable benefits to wine industry in terms of grape composition, wine style and schedule activities in the winery, particularly in wet and cool years. These trials provide the ftrst comprehensive data in eastern North America on the response of important hybrid and Vitis vinifera winegrape cultivars to irrigation management. Results from this study additionally might be a forward step in understanding the ABA metabolism, and its relationship with water status. Future research should be focused on ftnding the ABA threshold required to trigger the ripening process, and how this process could be controlled in cool climates.
    • An In-depth Examination of Personality and Aggression Across Different Contexts

      MacDonell, Elliott; Department of Psychology
      Acts of aggression are associated with a variety of negative outcomes. Accordingly, research has aimed to identify the personality traits that give rise to different forms of aggressive behaviour. Recent work has indicated that the factor of Honesty-Humility is associated with a variety of deviant behaviours, including aggression towards others; however, the nuances of these relationships require further investigation. This dissertation aimed to address several gaps in this literature through three main studies. In Study 1, we extended previous findings to younger populations, examining the associations between Honesty-Humility and aggression longitudinally in a large sample of children and youth. These findings demonstrated a bidirectional relationship between Honesty-Humility and aggression over time, such that low levels of Honesty-Humility resulted in higher levels of aggression and vice versa. In Study 2, we explored the specific facets of Honesty-Humility to determine if they differentially predict proactive and reactive aggression. Despite the theoretical link between Modesty and reactive aggression, we found limited support for this association, especially when controlling for proactive aggression. Overall, the Sincerity and Fairness facets were found to strongly predict both forms of aggression. Lastly, Study 3 explored the associations between Honesty-Humility and deviance, aggression, exploitation, and victimization in a workplace context. Robust relationships were found between Honesty-Humility and several deviant behaviours, further emphasizing the importance of this trait. In particular, when provided with the opportunity to aggress, individuals low in Honesty-Humility were more likely to do so, regardless of their level of power in the situation. Collectively, these findings indicate that Honesty-Humility is the strongest predictor of aggressive and deviant behaviour among the broad factors of personality. However, this dissertation extends previous findings by demonstrating the applicability of Honesty-Humility across different contexts and by providing a nuanced understanding of the components responsible for this relationship.
    • Indices and Implications of Emotional Underarousal for Persons with a History of Head Trauma

      Baker, Julie; Department of Psychology (Brock University, 2014-12-12)
      We examined the role of altered emotional functioning across the spectrum of injury severity (mild head injury [MHI], moderate/severe traumatic brain injury [TBI]), its implications for social behaviours, and the effect of modifying arousal and its relation to cognitive performance. In the first study (N = 230), students with self-reported MHI endorsed engaging in socially unacceptable and erratic behaviours significantly more often than did those with no MHI. We did not find significant differences between the groups in the measure of emotional intelligence (EI); however, for students who reported a MHI, scores on the EI measure significantly predicted reports of socially unacceptable behaviours such that lower scores predicted poorer social functioning, accounting for approximately 20% of the variance. Also, the experience of postconcussive symptoms was found to be significantly greater for students with MHI relative to their peers. In the second study (N = 85), we further examined emotional underarousal in terms of physiological (i.e., electrodermal activation [EDA]) and self-reported responsivity to emotionally-evocative picture stimuli. Although the valence ratings of the stimuli did not differ between students with and without MHI as we had expected, we found evidence of reduced and/or indiscriminate emotional responding to the stimuli for those with MHI which mimics that observed in other studies for persons with moderate/severe TBI. We also found that emotional underarousal followed a gradient of injury severity despite reporting a pattern of experiencing more life stressors. In the third study (N = 81), we replicated our findings of emotional underarousal for those with head trauma and also uniquely explored neuroendocrine aspects (salivary cortisol; cortisol awakening response [CAR]) and autonomic indices (EDA) of emotional dysregulation in terms of stress responsivity across the spectrum of injury severity (MHI [n = 32], moderate/severe TBI [n = 9], and age and education matched controls [n = 40]). Although the manipulation was effective in modifying arousal state in terms of autonomic and self-reported indices, we did not support our hypothesis that increased arousal would be related to improved performance on cognitive measures for those with prior injury. To our knowledge, this is the only study to examine the CAR with this population. Repeated measure analysis revealed that, upon awakening, students with no reported head trauma illustrated the typical CAR increase 45 minutes after waking, whereas, students who had a history of either mild head trauma or moderate/severe TBI demonstrated a blunted CAR. Thus, across the three studies we have provided evidence of emotional underarousal, its potential implications for social interactions, and also have identified potentially useful indices of dysregulated stress responsivity regardless of injury severity.
    • Individual Differences in Global/Local Processing Bias and the Attentional Blink

      Dale, Gillian; Department of Psychology (Brock University, 2014-01-27)
      When the second of two targets (T2) is presented temporally close to the first target (T1) in rapid serial visual presentation, accuracy to detect/identify T2 is markedly reduced as compared to longer target separations. This is known as the attentional blink (AB), and is thought to reflect a limitation of selective attention. While most individuals show an AB, research has demonstrated that individuals are variously susceptible to this effect. To explain these differences, Dale and Arnell (2010) examined whether dispositional differences in attentional breadth, as measured by the Navon letter task, could predict individual AB magnitude. They found that individuals who showed a natural bias toward the broad, global level of Navon letter stimuli were less susceptible to the AB as compared to individuals who showed a natural bias toward the detailed, local aspects of Navon letter stimuli. This suggests that individuals who naturally broaden their attention can overcome the AB. However, it was unclear how stable these individual differences were over time, and whether a variety of global/local tasks could predict AB performance. As such, the purpose of this dissertation was to investigate, through four empirical studies, the nature of individual differences in both global/local bias and the AB, and how these differences in attentional breadth can modulate AB performance. Study 1 was designed to examine the stability of dispositional global/local biases over time, as well as the relationships among three different global/local processing measures. Study 2 examined the stability of individual differences in the AB, as well as the relationship among two distinct AB tasks. Study 3 examined whether the three distinct global/local tasks used in Study 1 could predict performance on the two AB tasks from Study 2. Finally, Study 4 explored whether individual differences in global/local bias could be manipulated by exposing participants to high/low spatial frequencies and Navon stimuli. In Study 1, I showed that dispositional differences in global/local bias were reliable over a period of at least a week, demonstrating that these individual biases may be trait-like. However, the three tasks that purportedly measure global/local bias were unrelated to each other, suggesting that they measure unique aspects of global/local processing. In Study 2, I found that individual variation in AB performance was also reliable over a period of at least a week, and that the two AB task versions were correlated. Study 3 showed that dispositional global/local biases, as measured by the three tasks from Study 1, predicted AB magnitude, such that individuals who were naturally globally biased had smaller ABs. Finally, in Study 4 I demonstrated that these dispositional global/local biases are resistant to both spatial frequency and Navon letter manipulations, indicating that these differences are robust and intractable. Overall, the results of the four studies in this dissertation help clarify the role of individual differences in attentional breadth in selective attention.
    • Influence of adolescent social instability stress on the intake of ethanol and sucrose in a rodent model

      de Lima Marcolin, Marina; Department of Biological Sciences
      Adolescence is a sensitive period in which the effects of stress and alcohol can have long-lasting impacts. Social instability stress in adolescent rats (SS; postnatal day 30-45, daily 1 hour isolation + new cage partner) alters behavioural responses to psychostimulants and increases anxiety-like behaviour, but differences in voluntary consumption of natural and drug rewards are unknown. The main goal of my thesis was to investigate the effects of adolescent social instability stress (SS) on immediate and long-lasting changes on reward-related behaviours in male rats using voluntary alcohol intake paradigms. Another goal was to investigate the influence of social context on the propensity to drink alcohol, as well as the influence of these factors on sucrose intake. In chapter 2, I found that adolescent SS increased alcohol intake irrespective of social context, and adolescents drank more alcohol than adults. The intake of sucrose was not altered by stress, except during context of competition. In chapter 3, I found that history of alcohol drinking reduced synaptic plasticity markers in the dorsal hippocampus and prefrontal cortex, and this reduction was sometimes further reduced by SS. The propensity to drink alcohol was found not to differ between SS and CTL rats in the first experiment, and reduced among SS rats in the second experiment. After nine days of alcohol absence, the propensity to drink alcohol was not increased by previous alcohol access, and SS increased intake only in alcohol-naïve rats. History of alcohol drinking reduced anxiety-like behaviours and blunted SS-induced reduction in social interactions. Both SS and alcohol decreased corticosterone levels at baseline and after fear recall without changing freezing behaviour. My findings indicate that using a model of mild social stressor can have great impact on adolescent rats, but moderate effects in adult rats. The behavioural changes caused by stress can be enhanced later in life by history of alcohol drinking, but that does not necessarily cause an increase in the propensity to drink during adulthood, as other studies have shown. Adolescent stressed rats drink more alcohol than other groups, but they don’t seem to continue drinking more when they reach adulthood. These results indicate that the effects of social instability stress are transient in regards to propensity to drink, and can be the basis for alterations caused by both alcohol and stress.
    • The Influence of Attentional Focus on the Self-Efficacy-Performance Relationship in a Continuous Running Task

      LaForge-MacKenzie, Kaitlyn; Applied Health Sciences Program (Brock University, 2015-02-04)
      The self-efficacy-performance relationship in continuous sport tasks has been shown to be significantly reciprocal yet unequal with stronger influences in the performance-to-self-efficacy pathway rather than self-efficacy-to-performance pathway (e.g., LaForge-MacKenzie & Sullivan, 2014b). Bandura (2012) suggested that sociocognitive variables may influence this relationship. Attention as a sociocognitve factor may bias the processing of performance and self-efficacy information (Bandura, 1982, 1997; Bandura & Jourden, 1991). As confidence and attention are important aspects of peak running performance (Brewer, Van Raalte, Linder, & VanRaalte, 1991), the primary purpose of the present study was to examine the self-efficacy-performance relationship under three conditions of attentional focus. The secondary purpose was to examine self-efficacy and performance as separate constructs under the same conditions of attention. Participants ran continuously for one kilometer in one of three randomly assigned attentional focus conditions: internal-focus (n = 51), external-focus (n = 50), and control (n = 49). Self-efficacy was assessed using a one-item measure every 200 meters. Path analyses examining the primary objective revealed significant self-efficacy-to-performance pathways in all conditions: external-focus (p < .05, βs ranging from -.17 to -.32), internal-focus (p < .05, βs ranging from -.26 to -.36), and control (p < .05, βs ranging from -.29 to -.42). Significant reciprocal relationships were absent in all conditions. ANOVAs examining the secondary objectives found significantly faster performance in the control condition at the start (F (2, 147) = 3.86, p < .05) and end of the task (F (2, 147) = 3.56, p < .05). Self-efficacy was significantly higher in the internal-focus condition at the end of the task (Self-Efficacy 4 (F (2, 147) = 3.21, p < .05) and Self-Efficacy 5 (F (2, 147) = 4.74, p < .05). In contrast to previous within-trial research (e.g., LaForge-MacKenzie & Sullivan, 2014b) self-efficacy-to-performance effects were more significant and robust than performance-to-self-efficacy effects. These results provided support for Bandura’s (2012) suggestion that sociocognitive factors may have the ability to alter the causal structure of the self-efficacy-performance relationship, proposing complexities in the self-efficacy-performance relationship (Sitzmann &Yeo, 2013). Results were discussed from both theoretical and applied perspectives.
    • The Influence of Cerebral Blood Flow and Carbon Dioxide on Neuromuscular Responses During Environmental Stress

      Hartley, Geoffrey L.; Applied Health Sciences Program
      Although reductions in cerebral blood flow (CBF) may be implicated in the development of central fatigue during environmental stress, the contribution from hypocapnia-induced reductions in CBF versus reductions in CBF per se has yet to be isolated. The current research program examined the influence of CBF, with and without consequent hypocapnia, on neuromuscular responses during hypoxia and passive heat stress. To this end, neuromuscular responses, as indicated by motor evoked potentials (MEP), maximal M-wave (Mmax) and cortical voluntary activation (cVA) of the flexor carpi radialis muscle during isometric wrist flexion, was assessed in three separate projects: 1) hypocapnia, independent of concomitant reductions in CBF; 2) altered CBF during severe hypoxia and; 3) thermal hyperpnea-mediated reductions in CBF, independent of hypocapnia. All projects employed a custom-built dynamic end-tidal forcing system to control end-tidal PCO2 (PETCO2), independent of the prevailing environmental conditions, and cyclooxygenase inhibition using indomethacin (Indomethacin, 1.2 mg·Kg-1) to selectively reduce CBF (estimated using transcranial Doppler ultrasound) without changes in PETCO2. A primary finding of the present research program is that the excitability of the corticospinal tract is inherently sensitive to changes in PaCO2, as demonstrated by a 12% increase in MEP amplitude in response to moderate hypocapnia. Conversely, CBF mediated reductions in cerebral O2 delivery appear to decrease corticospinal excitability, as indicated by a 51-64% and 4% decrease in MEP amplitude in response to hypoxia and passive heat stress, respectively. The collective evidence from this research program suggests that impaired voluntary activation is associated with reductions in CBF; however, it must be noted that changes in cVA were not linearly correlated with changes in CBF. Therefore, other factors independent of CBF, such as increased perception of effort, distress or discomfort, may have contributed to the reductions in cVA. Despite the functional association between reductions in CBF and hypocapnia, both variables have distinct and independent influence on the neuromuscular system. Therefore, future studies should control or acknowledge the separate mechanistic influence of these two factors.
    • Influence of upper limb ischaemia-reperfusion injury on the regulation of cutaneous blood flow during local thermal hyperaemia

      McGarr, Gregory Walter; Applied Health Sciences Program
      The present research was developed to investigate the effects of acute upper limb ischaemia- reperfusion (I-R) on neurovascular and endothelial control of the cutaneous micro-circulation in the forearm and finger by evaluating its influence on the magnitude and kinetics of the vasodilatory response to local skin heating. Study 1 investigated between-day reliability of the local heating response in non-glabrous and glabrous index finger skin. Study 2 investigated the effects of I-R on the local heating response in non-glabrous and glabrous skin of the index finger. Study 3 investigated within- and between-day reliability of the local heating response in non-glabrous forearm skin. Study 4 investigated the effects of I-R on the local heating response in non-glabrous forearm skin, as well as the contribution of sensory nerves in mediating the magnitude and kinetics of this response. When data were normalized for blood pressure and expressed as cutaneous vascular conductance (CVC) reliability was generally comparable across all skin sites. In non-glabrous skin reliability was superior when CVC was normalized to maximum heating. At all skin sites, normalizing CVC to baseline produced poor results. Vasodilatory onset time and time to initial peak during local heating produced moderate to good reliability for all skin sites in Studies 1 and 3. In the finger, I-R did not influence the magnitude of the local heating response for the initial peak or plateau phases in either skin type. However, I-R did cause a ~23% delay in vasodilatory onset time and a ~16% delay in time to initial peak in non-glabrous skin. In the forearm, I-R attenuated the initial peak and plateau phases by ~31% and ~34%, respectively. Vasodilatory onset time was also delayed by 34% post-ischaemia. The contribution of sensory nerves in mediating the initial peak and vasodilatory onset time were significantly reduced post-ischaemia, while sensory nerves did not influence the plateau. It is concluded that upper limb I-R impairs the local heating response in non-glabrous forearm and index finger skin. A combination of cutaneous sensory nerve impairment and reduced nitric oxide bioavailability appear to be responsible for attenuating the vasodilatory response to local skin heating under these conditions.
    • Informal Teacher Leaders: Secondary School Teachers’ Perceptions of How They Collaboratively Construct and Implement Classroom Assessment Policy and Practice

      Clarke, Kristen A; Department of Graduate and Undergraduate Studies in Education
      Secondary school teachers enact informal teacher leadership to move their instructional and assessment practices forward by leveraging existing structures and navigating micropolitical contexts. Leadership cannot be oversimplified as the work of an individual because of the complex and interwoven nature of schools and the current political climate of educational settings. Informal teacher leaders (ITLs) co-create roles based on needs that focus on supporting learning for students, for colleagues, and for themselves. This study used a constructivist lens and inquiry methodology to explore perceptions of informal secondary school teacher leaders as they collaboratively construct and implement classroom assessment policy and practice. The study highlights the perceived purpose and nature of informal teacher leadership; organizational factors and conditions that ITLs face when working collaboratively to improve assessment practices; and strategies that these teachers leverage to navigate changes in assessment practice and policy. (Note: a provincial review of assessment was conducted during completion of this dissertation.) This qualitative study explored informal teacher leadership and assessment practice and policy through semi-structured interviews, focus groups, document analysis, and memoing. The research encompassed 28 participants, 11 of whom are ITLs in a suburban school district in Ontario. Findings reveal how ITLs structure their roles to be responsive, reciprocal, reflective, and results oriented. Recommendations are provided to inform educators and policy developers at the provincial, district, and school level for both supporting informal teacher leadership and developing assessment literacy.
    • Infrared Spectroscopy of Ge:Mn Thick Films Prepared by Ion Implantation and Post-annealing

      Obied, Laila Hassan; Department of Physics
      An infrared transmission study of Ge:Mn systems is presented in this work. Various Ge:Mn samples have been prepared by both single (Mn2+ ion energy 4.76 MeV, dose 2x10^16 /cm^2) or multiple (dose 1x10^16 /cm^2) into high resistivity (100) Ge substrates. Both conventional and flash lamp annealing procedures have been used to prepare a set of samples that were characterized by X-ray Diffraction (XRD), Secondary Ion Mass Spectrometry (SIMS) and magnetometry as well as infrared transmission spectroscopy (60-8000 cm^-1). After implantation, the Ge:Mn layers are about 3 mm thick and amorphous as revealed by XRD. Samples conventionally annealed at temperatures below 250C maintained their amorphous structure. Samples annealed at temperature above 330C recrystallized into a polycrystalline structure. SIMS measurements show that the diffusion of Mn is greatly affected by the starting distribution and that diffusion is much higher in samples prepared with the lower total Mn dose. The presence of multiple magnetic phases in all the annealed samples was indicated by field and temperature dependent measurements of the total moment. Our diverse preparations suggest that the formation of secondary phases in Ge:Mn system in unavoidable. Magnetic measurements suggest that the maximum volume fraction of metallic Mn5Ge3 inclusions is of the order of 1x10^-3, much lower than the percolation threshold of metallic inclusions in an insulating matrix. Infrared transmission measurements on the same samples show the presence of a low frequency Drude like absorption with high hole concentration (p~10^ 18 /cm^3) which is greater than the critical density for metal-insulator (MI) transition in Ge. This observation suggests Mn has crystallized in substitutional sites to a far greater degree than was achieved with traditional equilibrium crystal growth. The MI transition has been investigated in the Ge:Mn system by studying the temperature dependent transmission between 4K and 300K and comparing to similar measurements on a sample of Ga-doped Ge with p = 1.5x10^16 /cm^3 which is on the insulating side of the MI transition. Finally, absorption was observed that may possibly be attributed to Mn5Ge3 inclusions in the Ge:Mn matrix.
    • INHUMAN TARGETS: Psychopathy, Dehumanization, and Sexist and Violent Attitudes Towards Women

      Methot-Jones, Tabitha; Department of Psychology
      The current work presents three studies that examined the role of dehumanization in the association between psychopathy and sexist and violent attitudes towards women. This program had two overarching goals in examining psychopathy, dehumanization, and sexist and violent attitudes towards women. The first goal was to examine whether an indirect association between psychopathy and negative attitudes towards women existed through dehumanization. The second goal was to explore if, by introducing information that humanizes women, levels of dehumanization could be mitigated for individuals high on psychopathic traits. Employing mixed samples for both studies (student and community), Study 1 (n = 514) and Study 2 (n = 202) provided evidence that psychopathy demonstrated an indirect relationship with sexist and violent attitudes towards women via dehumanization. Study 2 also expanded on Study 1 by including a behavioural measure of violent attitudes towards women. Finally, Study 3 (n = 206), again using a mixed sample, attempted to manipulate dehumanization to see if it, and the sexist and violent attitudes associated with it, would be mitigated. Unfortunately, the manipulation failed, but we were able to use the data from Study 3 to provide a replication of the results of Study 2. Across three studies results suggested that the path from psychopathy to negative attitudes towards women was at least partially (if not fully) indirect through dehumanization. This suggests that dehumanization may be an important mechanism to consider when examining the tendency of individuals high in psychopathic traits to engage in violence towards women. Furthermore, because psychopathic traits are associated with violence perpetrated against women, dehumanization could be an important construct to consider when examining potential avenues for clinical interventions. Even more broadly, dehumanization could be an important construct for mitigating the association between psychopathy and violence generally.
    • Institutional Dimensions of Professional Knowledge: Implications for School Administrators’ Constructions of Equitable Leadership Knowledge in Kenya and Canada

      Oyugi, Perez; Department of Graduate and Undergraduate Studies in Education
      This international comparative study employed a constructivist grounded theory approach to explore the influence of institutional factors on school administrators’ constructions of equitable leadership knowledge and practice in Kenya and Canada. Six principals and vice principals from Kisumu County, Kenya and 5 from Ontario, Canada participated in the study. An institutional theory lens is used to compare and illuminate the processes school administrators used to link institutional imperatives to equitable leadership knowledge and practice. First, the results indicate that equitable leadership is an emerging concept in Kenya among school principals. Second, the results confirm that equitable leadership knowledge and practice is nested within regulative, normative, and cognitive pillars that underlie educational institutions in Kenya and Canada. Third, results show that equitable leadership knowledge arose out of interactions between institutional actors and from institutional processes for sensemaking and for organizing knowledge in both countries. Fourth, a three-stage process theory—mimetic, normalizing, and transference stages—emerged from the data to connect equitable leadership knowledge to institutional obligations.
    • The interaction of sleep and hormones on emotion functioning

      Lustig, Kari; Department of Psychology
      Insufficient sleep has been associated with deficits in emotion processing; sleepy individuals show increased emotional reactivity and decreased emotion regulation. Individual differences that predict performance after sleep loss has remained largely elusive. Concentrations of cortisol, progesterone, and testosterone are candidate predictors for variability in performance following sleep loss. These hormones are associated with emotion functioning under well-rested conditions and show interactions with sleep and circadian rhythms. The central aim of this dissertation was to investigate the interaction of natural sleep and hormones on measures of emotion functioning. Study 1 examined the role of cortisol in the relationship between sleep (across the first three years of university), and self reported emotion functioning in undergraduate students. Poor sleep was associated with worse emotion regulation and reactivity, and greater concentrations of cortisol and cortisol/DHEA-S. Consistently poor sleepers over three years, who had high cortisol, experienced the greatest difficulties with emotion regulation. Study 2 investigated the association between sleep satisfaction and objective measures of sleep on self-reported emotional functioning in a group of children and adolescents. Importantly, in girls who were dissatisfied sleepers, being further though puberty was associated with the greatest difficulties with emotion regulation. Study 3 examined natural sleep, hormones, and menstrual phase on processing emotional stimuli. Participants completed sleep diaries and wore actigraphy watches for 3-weeks and completed measures of emotion perception on two occasions in the laboratory, in different menstrual phases for women. The study supported dynamic relationships between hormone concentrations and various measures of sleep duration and quality on the processing of emotion stimuli. Many relationships emerged for threatening emotions, indicating that high concentrations of testosterone, progesterone or cortisol, combined with poor sleep resulted in increased sensitivity towards threat detection. Together these studies provide evidence that hormones are an important factor in understanding the link between poor sleep and emotion functioning. Hormone concentration plays a role in understanding individual differences in response to sleep loss and can compound with sleep loss to result in worse emotional outcomes. Consideration of hormonal factors may help identify certain at-risk populations for sleep related deficits or timing of interventions.
    • Interactions and Population Dynamics Between Erwinia amylovora, Pantoea agglomerans, and their Bacteriophages for Effective Phage Therapy

      Gayder, Steven C; Centre for Biotechnology
      Fire blight is a globally devastating disease of apples, pears, and other rosaceous plants caused by the bacterial phytopathogen Erwinia amylovora. Our lab is developing a dual-action biological control product using the epiphytic bacterial antagonist Pantoea agglomerans and a cocktail of bacterial viruses called bacteriophages. P. agglomerans act as host cells for a cocktail of phages targeting E. amylovora in planta and also exclude the pathogen from the blossom pistil and hypanthia by natural antagonism and antibiotic production. The objective of this research is to understand the dynamics between the pathogen, the carrier, and their phages and use this information to develop an effective phage-carrier system for the control of E. amylovora. A novel DNA plasmid was created which allows simultaneous quantification of E. amylovora, P. agglomerans, and four Erwinia phage species using quantitative real-time PCR (qPCR). This plasmid standard-based qPCR was used to study the host range of 10 phages against a global collection of Erwinia strains (n=106) and potential carriers (n=30), and to study the population dynamics of Erwinia phages in different host and cocktail combinations in unprecedented detail. The host range on E. amylovora revealed global phage resistance is located largely in western North America, and this resistance is due in part to a greater effect of exopolysaccharide production by these hosts. Also three phages, ɸEa21-4, ɸEa46-1-A1, and φEa35-70, were chosen to investigate for potential biocontrol efficacy. Phage ɸEa35-70, while ineffective alone, synergized with both ɸEa21-4 and ɸEa46-1-A1 for enhanced reduction of E. amylovora growth over 24 h. The competition between ɸEa21-4 and ɸEa35-70 was exploited which maximized carrier survival and lead to the design of an effective phage-carrier combination which will be formulated and further investigated for the control of E. amylovora in planta. Finally, the quantitative host range data and host genomic sequences were used to identify 10 host genes that are potentially associated with phage infection using a novel, k-mer based, genome wide association study (GWAS). These genes are indicative of a potential phage receptor, two novel phage resistance mechanisms, and other metabolic and biological functions which may affect phage infection.