7 resultados para variance effective population size

em Brock University, Canada


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This study examined the effectiveness of motor-encoding activities on memory and performance of students in a Grade One reading program. There were two experiments in the study. Experiment 1 replicated a study by Eli Saltz and David Dixon (1982). The effect of motoric enactment (Le., pretend play) of sentences on memory for the sentences was investigated. Forty Grade One students performed a "memory-for-sentences" technique, devised by Saltz and Dixon. Only the experimental group used motoric enactment of the sentences. Although quantitative findings revealed no significant difference between the mean scores of the experimental group versus the control group, aspects of the experimental design could have affected the results. It was suggested that Saltz and Dixon's study could be replicated again, with more attention given to variables such as population size, nature of the test sentences, subjects' previous educational experience and conditions related to the testing environment. The second experiment was an application of Saltz and Dixon's theory that motoric imagery should facilitate memory for sentences. The intent was to apply this theory to Grade One students' ability to remember words from their reading program. An experimental gym program was developed using kinesthetic activities to reinforce the skills of the classroom reading program. The same subject group was used in Experiment 2. It was hypothesized that the subjects who experienced the experimental gym program would show greater signs of progress in reading ability, as evidenced by their scores on Form G of the Woodcock Reading Mastery Test--Revised. The data from the WRM--R were analyzed with a 3-way split-plot analysis of variance in which group (experimental vs. control) and sex were the between subjects variables and test-time (pre-test vs. post-test) was the within-subjects variable. Findings revealed the following: (a) both groups made substantial gains over time on the visual-auditory learning sub-test and the triple action of group x sex x time also was significant; (b) children in the experimental and control groups performed similarly on both the pre- and post-test of the letter identification test; (c) time was the only significant effect on subjects' performance on the word identification task; (d) work attack scores showed marked improvement in performance over time for both the experimenta+ and control groups; (e) passage comprehension scores indicated an improvement in performance for both groups over time. Similar to Experiment 1, it is suggested that several modifications in the experimental design could produce significant results. These factors are addressed with suggestions for further research in the area of active learning; more specifically, the effect of motor-encoding activities on memory and academic performance of children.

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A naturally occurring population of photosynthetic bacteria, located in the meromictic Crawford Lake, was examined during two field seasons (1979-1981). Primary production, biomass, light intensity, lake transparency, pH and bicarbonate concentration were all monitored during this period at selected time intervals. Analysis of the data indicated that (l4C) bacterial photosynthesis was potentially limited by the ambient bicarbonate concentration. Once a threshold value (of 270 mg/l) was reached a dramatic (2 to 10 fold) increase in the primary productivity of the bacteria was observed. Light intensity appeared to have very little effect on the primary productivity of the bacteria, even at times when analyses by Parkin and Brock (1980a) suggested that light intensity could be limiting (i.e., 3.0-5.0 ft. candles). Shifts in the absorption maxima at 430 nrn of the .bacteriochlorophyll spectrum suggested that changes in the species or strain composition of the photosynthetic bacteria had occurred during the summer months. It was speculated that these changes might reflect seasonal variation in the wavelength of light reaching the bacteria. Chemocline erosion did not have the same effect on the population size (biomass) of the photosynthetic bacteria in Crawford Lake (this thesis) as it did in Pink Lake (Dickman, 1979). In Crawford Lake the depth of the chemocline was lowered with no apparent loss in biomass (according to bacteriochlorophyll data). A reverse current was. proposed to explain the observation. The photosynthetic bacteria contributed a significant proportion (10-60%) of the lake1s primary productivitya Direct evidence was obtained with (14C) labelling of the photosynthetic bacteria, indica.ting that the zooplankton were grazing the photosynthetic bacteria. This indicated that some of the photosynthetic bacterial productivity was assimilated into the food chain of the lake. Therefore, it was concluded that the photosynthetic bacteria made a significant contribution to the total productivity of Crawford Lake.

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Existing research identifies preschoolers with communication delays as a population at risk for the development of behavioural concerns. This risk increases when additional environmental factors such as parental stress and family conflict are also present. Research has also shown that behavioural concerns can be stable over time when they develop early. However, early intervention has been shown to be effective in addressing these concerns. The effectiveness of early intervention in addressing both child and family outcomes increases when interventions are delivered in a family-centred approach. This research project made use of data related to child behaviour and parenting, gathered through the Family Resource Project which explored the parenting experiences and resource access and allocation decisions of families who have preschool children with and without communication delays. Cluster analysis was used to explore whether there were identifiable clusters of children and families within each sample. Interview data fi"om each identified family cluster was then explored further, to identify how parents described their child's behaviour and their experience of parenting. Results show that, within this sample, parents of preschoolers with communication delays described their child's behaviour and their experience of parenting differently than did parents of children without communication delays. Results also showed that within this sample parents experiencing parental stress and/or family conflict described their child's behaviour and their experience of parenting differently than did parents from other clusters. Results suggest support for early intervention and the use of family-centred intervention, particularly for families of children with communication delays.

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Despite the confimied health benefits of exercise during the postpartum period, many new mothers are not sufficiently active. The present research aimed to examine the effectiveness of 2 types of messages on intention to exercise after giving birth on 2 groups of pregnant women (low and high self-monitors) using the Theory of Planned Behavior as a theoretical basis. Participants were 2 1 8 pregnant women 1 8 years of age and older (Mean age = 27.9 years, SD = 5.47), and in their second or third trimester. Women completed a demographics questionnaire, a self-monitoring (SM) scale and the Godin Leisure Time Exercise Questionnaire for current and pre-pregnancy exercise levels. They then read one of two brochures, describing either the health or appearance benefits of exercise for postpartum women. Women's attitudes, social norms, perceived behavioral control, and intentions to exercise postpartum were then assessed to determine whether one type of message (health or appearance) was more effective for each group. A MANOVA found no significant effect (p>0.05) for message type, SM, or their interaction. Possible reasons include the fact that the two messages may have been too similar, reading any message about exercise may result in intentions to exercise, or lack of attention given to the brochure. Given the lack of research in this area, more studies are necessary to confirm the present results. Two additional exploratory analyses were conducted. Pearson correlations found higher levels of pre-pregnancy exercise and current exercise to be associated with more positive attitudes, more positive subjective norms, higher perceived behavioral control, and higher intention to exercise postpartum. A hierarchical regression was conducted to determine the predictive utility of attitudes, subjective norms, and perceived behavioral control on intention for each self-monitoring group. Results of the analysis demonstrated the three independent variables significantly predicted intention (p < .001) in both groups, accounting for 58-62% of the variance in intention. For low self-monitors, attitude was the strongest predictor of intention, followed by perceived behavioral control and subjective norm. For high self-monitors, perceived behavioral control was the strongest predictors, followed by attitudes and subjective norm. The present study has practical and real world implications by contributing to our understanding of what types of messages, in a brochure format, are most effective in changing pregnant women's attitudes, subjective norm, perceived behavioral control and intention to exercise postpartum and provides ftirther support for the use of the Theory of Planned Behavior with this population.

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House Finches (CarpQdacqs mexiCAnuS) were introduced to Long Island, New York from southern'California in 1940. Apparently, an initial sample of less than 100 birds has given rise to a population that now occupies much of the eastern United States. This study was to determine if morphological and reproductive changes have taken place in introduced eastern birds, which have colonized a novel environment. A study area in Goleta, California (CAL) represented the parental population whereas for comparison, House Finches in St. Catharines, Ontario (ONT) represented the introduced population. Interlocality variation in 25 morphometric characters of 100 adult House Finches was examined statistically. Singleclassification analysis of variance revealed significant interlocality differentiation in seven characters of males and nine of females. Females showed differentiation in more limb elements than males. Analysis of character variation using discriminant and principal component analysis distinguished samples on the basis of variation in shape. Compared to CAL, aNT birds (especially females) had smaller extremities relative to certain core parts and weight. Females showed similar patterns of character covariation in each locality on the second principal component, which suggests that differentiation of the ONT population may not be solely environmentally induced. Sexual dimorphism was evident in four charaoters in aNT and five in CAL. Disoriminant analysis distinguished sex on the basis of variation in shape. Males possessed a relatively larger flying apparatus and small.er hind limbs than females. The dearee of sexual dimorphism did not vary sicnifioantly between looalities. 3 Data on reproduotive parameters were oolleoted in 1983 and 1984 in ONT, and 1984 in CAL. In 1984, Bouse Finohes began breedina approximately three months earlier in CAL than in ONT. In ONT, there was no sianifioant differenoe in mean olutoh initiation date between 1983 and 1984. In both looalities most nests oontained either four or five ea",s, and olutoh size differenoes between looalites were not signifioant. Seasonal deolines in olutch size were evident in ONT but not in CAL. Intralooality variation in e.g weight and size was not related to clutch size. E",g weiaht showed no seasonal trend in ONT, but inoreased sianifioantly with breed ina season in OAL. In both looalities e8'''' weiaht increased sipifioantly with order of layina in olutohes of four but not in clutohes of five. Eag's in ONT in 1983 and 1984 were sip.ificantly larser than in CAL in 1984. The modal inoubation period was 13 days and did not vary sip.ifioantly between localites. In both looalities nestling weiaht on the day of hatohing was oorrelated to fresh ega welaht. For muoh of the period between hatohing and 14 days post-hatoh, ONT nestlinas were signifioantly laraer than CAL nestlings in terms of weiaht. bill length, bill depth, and manus length.

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Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.

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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.