7 resultados para trigger
em Brock University, Canada
Resumo:
The purpose of this research study was to develop a conceptual model through the use of a grounded theory approach, which explains how trigger events are related to leadership development. Trigger events are experience that cause developmental growth and may result in an increased ability to lead (Luthans and Avolio (2003). In this study, there were two phases of data collection. First participants completed the Washington University Sentence Completion Test (WUSCT), where their respective leadership developmental stage was measured. Second, participants were involved in two in-depth interviews where an understanding was reached as to how various trigger events have impacted their leadership development. From these data, a conceptual model was developed to explain the relationship between trigger events and leadership development. Participants described trigger events as being important developmental periods, during which time they grew as people and became more capable leaders.
Resumo:
With incidence rates of osteoporosis increasing (Osteoporosis Canada, 2007), preventative efforts to minimize costs associated with condition diagnosis are a public health priority. Cues to action are specific internal (e.g., physical symptoms, family member with a condition) or external stimuli (e.g., public service announcements, health education campaigns) that are necessary to trigger appropriate health behaviours and serve to create an awareness of the health threat (Mattson, 1999). To date, limited understanding of the scope of influence cues to action have on health beliefs and behaviour associated with osteoporosis is known. The present investigation was designed to address this gap in the literature. More specifically, the influence of cues to action, a public service announcement (PSA) developed by Osteoporosis Canada and a bone screening by way of Quantitative Ultrasound, on health beliefs and health-enhancing physical activity (HEPA) across a four week period was investigated. Peri-and postmenopausal women (N= 174) were randomly assigned to one of three conditions 1) an osteoporosis public service announcement (PSA) condition; 2) a bone screening condition via quantitative ultrasound techniques, and 3) a PSA attention control condition. Health beliefs associated with osteoporosis were taken at three time points: prior to the cue to action intervention, immediately following the intervention, and four weeks post intervention. Knowledge of osteorporosis risk factors and HEP A were assessed pre and post-intervention only. Results of a regression analysis suggested that baseline health beliefs predicted baseline HEPA (R2 adj = .24; F (9, 161) = 6.49,p = .000; 95% CI = .12 - .35) with exercise barriers (p = -.33) being a negative predictor and health motivation (p = .21) being a positive predictor of HEP A. Baseline health beliefs predicted With incidence rates of osteoporosis increasing (Osteoporosis Canada, 2007), preventative efforts to minimize costs associated with condition diagnosis are a public health priority. Cues to action are specific internal (e.g., physical symptoms, family member with a condition) or external stimuli (e.g., public service announcements, health education campaigns) that are necessary to trigger appropriate health behaviours and serve to create an awareness of the health threat (Mattson, 1999). To date, limited understanding of the scope of influence cues to action have on health beliefs and behaviour associated with osteoporosis is known. The present investigation was designed to address this gap in the literature. More specifically, the influence of cues to action, a public service announcement (PSA) developed by Osteoporosis Canada and a bone screening by way of Quantitative Ultrasound, on health beliefs and health-enhancing physical activity (HEPA) across a four week period was investigated. Peri-and postmenopausal women (N= 174) were randomly assigned to one of three conditions 1) an osteoporosis public service announcement (PSA) condition; 2) a bone screening condition via quantitative ultrasound techniques, and 3) a PSA attention control condition. Health beliefs associated with osteoporosis were taken at three time points: prior to the cue to action intervention, immediately following the intervention, and four weeks post intervention. Knowledge of osteorporosis risk factors and HEP A were assessed pre and post-intervention only. Results of a regression analysis suggested that baseline health beliefs predicted baseline HEPA (R2 adj = .24; F (9, 161) = 6.49,p = .000; 95% CI = .12 - .35) with exercise barriers (p = -.33) being a negative predictor and health motivation (p = .21) being a positive predictor of HEP A. Baseline health beliefs predicted
Resumo:
The nature of this research is to investigate paleoseismic deformation of glacial soft sediments from three sampling sites throughout the Scottish Highlands; Arrat's Mills, Meikleour and Glen Roy. The paleoseismic evidence investigated in this research will provide a basis for applying criteria to soft sediment deformation structures, and the trigger mechanisms that create these structures. Micromorphology is the tool used in this to investigate paleoseismic deformation structures in thin section. Thin section analysis, (micromorphology) of glacial sediments from the three sampling sites is used to determine microscale evidence of past earthquakes that can be correlated to modem-day events and possibly lead to a better understanding of the impact of earthquakes throughout a range of sediment types. The significance of the three sampling locations is their proximity to two major active fault zones that cross Scotland. The fault zones are the Highland Boundary Fault and the Great Glen Fault, these two major faults that parallel each other and divide the country in half Sims (1975) used a set of seven criteria that identified soft sediment deformation structures created by a magnitude six earthquake in Cahfomia. Using criteria set forth by Sims (1975), the paleoseismic evidence can be correlated to the magnitude of the deformation structures found in the glacial sediments. This research determined that the microstructures at Arrat's Mill, Meikleour and Glen Roy are consistent with a seismically induced origin. It has also been demonstrated that, even without the presence of macrostructures, the use of micromorphology techniques in detecting such activity within sediments is of immense value.
Resumo:
Ultrasonic vocalization plays an important role in intraspecies communication for rats. It has been well demonstrated that rats will emit 22kHz vocalization in stressfiil or threatening situations. Although the neural mechanism underlying vocahzation is not well understood, it is known that chohnergic input to the basal forebrain induces such alarm calls. A number of experiments have found that intracerebral injection of carbachol, a predominantly muscarinic agonist, into die anterior hypothalamic/preoptic area (AH/POA) rehably induces vocalization similar to naturally emitted ultrasonic calls. It has also been shown that carbachol has extensive inhibitory effects on neuronal firing in the same area. This result impUes that the inhibitory effects of carbachol in the AH/POA could trigger vocahzation, and that the GABAergic system could be involved. The purpose of this study is to investigate the effects ofGABA agonists and antagonists on flie production of carbachol induced 22kHz vocalization. The following hypotheses were examined: 1) apphcation ofGABA (a naturally occurring inhibitory neurotransmitter) will have a synergistic effect with carbachol, increasing vocalization; and 2) tiie apphcation ofGABA antagonists (picrotoxin or bicuculline) will reduce caibachol-induced vocalization. A total of sixty rats were implanted with stainless steel guide cannulae in the AH/POA area. After recovery, animals were locally pretreated with 1) GABA (l-40ng), 2) picrotoxin (1 .5^g) or bicuculhne (0.03ng), or 3) sahne; before injection with carbachol (1 .5^g). The resulting vocalization was measured and quantitated. The results indicate that pretreatment with GABA or GABA antagonists had no significant effect on vocalization. Local pretreatment with GABA did not potentiate the vocal response as measured by its duration, latraicy, and total number of calls. Similarly, pretreatment with picrotoxin or bicuculline had no effects on the same measures of vocalization. The results suggest tfiat chohnoceptive neurons involved in the production of alarm calls are not under direct GABAergic control.
Resumo:
Both learning and basic biological mechanisms have been shown to play a role in the control of protein int^e. It has previously been shown that rats can adapt their dietary selection patterns successfully in the face of changing macronutrient requirements and availability. In particular, it has been demonstrated that when access to dietary protein is restricted for a period of time, rats selectively increase their consumption of a proteincontaining diet when it becomes available. Furthermore, it has been shown that animals are able to associate various orosensory cues with a food's nutrient content. In addition to the role that learning plays in food intake, there are also various biological mechanisms that have been shown to be involved in the control of feeding behaviour. Numerous studies have documented that various hormones and neurotransmitter substances mediate food intake. One such hormone is growth hormone-releasing factor (GRF), a peptide that induces the release of growth hormone (GH) from the anterior pituitary gland. Recent research by Vaccarino and Dickson ( 1 994) suggests that GRF may stimulate food intake by acting as a neurotransmitter in the suprachiasmatic nucleus (SCN) and the adjacent medial preoptic area (MPOA). In particular, when GRF is injected directly into the SCN/MPOA, it has been shown to selectively enhance the intake of protein in both fooddeprived and sated rats. Thus, GRF may play a role in activating protein consumption generally, and when animals have a need for protein, GRF may serve to trigger proteinseeking behaviour. Although researchers have separately examined the role of learning and the central mechanisms involved in the control of protein selection, no one has yet attempted to bring together these two lines of study. Thus, the purpose of this study is to join these two parallel lines of research in order to further our understanding of mechanisms controlling protein selection. In order to ascertain the combined effects that GRF and learning have on protein intake several hypothesis were examined. One major hypothesis was that rats would successfully alter their dietary selection patterns in response to protein restriction. It was speculated that rats kept on a nutritionally complete maintenance diet (NCMD) would consume equal amount of the intermittently presented high protein conditioning diet (HPCD) and protein-free conditioning diet (PFCD). However, it was hypothesized that rats kept on a protein-free maintenance diet (PFMD) would selectively increase their intake of the HPCD. Another hypothesis was that rats would learn to associate a distinct marker flavour with the nutritional content of the diets. If an animal is able to make the association between a marker flavour and the nutrient content of the food, then it is hypothesized that they will consume more of a mixed diet (equal portion HPCD and PFCD) with the marker flavour that was previously paired with the HPCD (Mixednp-f) when kept on the PFMD. In addition, it was hypothesized that intracranial injection of GRF into the SCN/MPOA would result in a selective increase in HPCD as well as Mixednp-t consumption. Results demonstrated that rats did in fact selectively increase their consumption of the flavoured HPCD and Mixednp-f when kept on the NCMD. These findings indicate that the rats successfully learned about the nutrient content of the conditioning diets and were able to associate a distinct marker flavour with the nutrient content of the diets. However, the results failed to support previous findings that GRF increases protein intake. In contrast, the administration of GRF significantly reduced consumption of HPCD during the first hour of testing as compared to the no injection condition. In addition, no differences in the intake of the HPCD were found between the GRF and vehicle condition. Because GRF did not selectively increase HPCD consumption, it was not surprising that GRF also did not increase MixedHP-rintake. What was interesting was that administration of GRF and vehicle did not reduc^Mixednp-f consumption as it had decreased HPCD consumption.
Resumo:
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.
Resumo:
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.