12 resultados para Micronucleus test

em Brock University, Canada


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Although alcohol problems and alcohol consumption are related, consumption does not fully account for differences in vulnerability to alcohol problems. Therefore, other factors should account for these differences. Based on previous research, it was hypothesized that risky drinking behaviours, illicit and prescription drug use, affect and sex differences would account for differences in vulnerability to alcohol problems while statistically controlling for overall alcohol consumption. Four models were developed that were intended to test the predictive ability of these factors, three of which tested the predictor sets separately and a fourth which tested them in a combined model. In addition, two distinct criterion variables were regressed on the predictors. One was a measure of the frequency that participants experienced negative consequences that they attributed to their drinking and the other was a measure of the extent to which participants perceived themselves to be problem drinkers. Each of the models was tested on four samples from different populations, including fIrst year university students, university students in their graduating year, a clinical sample of people in treatment for addiction, and a community sample of young adults randomly selected from the general population. Overall, support was found for each of the models and each of the predictors in accounting for differences in vulnerability to alcohol problems. In particular, the frequency with which people become intoxicated, frequency of illicit drug use and high levels of negative affect were strong and consistent predictors of vulnerability to alcohol problems across samples and criterion variables. With the exception of the clinical sample, the combined models predicted vulnerability to negative consequences better than vulnerability to problem drinker status. Among the clinical and community samples the combined model predicted problem drinker status better than in the student samples.

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This study examined the effects of providing students with explicit instruction in how to use a repertoire of reading comprehension strategies and test taking skills when reading and responding to three types of questions (direct, inferential, critical). Specifically, the study examined whether providing students with a "model" of how to read and respond to the text and to the comprehension questions improved their reading comprehension relative to providing them with implicit instruction on reading comprehension strategies and test taking skills. Students' reading comprehension and test taking performance scores were compared as a function of instructional condition. Students from 2 grade 8 classes participated in this study. The reading component of the Canadian Achievement Tests, Third Edition (CAT/3) was used to identify students' level of reading comprehension prior to the formal instructional sessions. Students received either explicit instruction, which involved modelling, or implicit instruction, which consisted of review and discussion of the strategies to be used. Comprehension was measured through the administration of formative tests after each instructional session. The formative tests consisted of reading comprehension questions pertaining to a specific form of text (narrative, informational, graphic). In addition, students completed 3 summative tests and a delayed comprehension test which consisted of the alternative version of the CAT/3 standardized reading assessment. These data served as a posttest measure to determine whether students had shown an improvement in their reading comprehension skills as a result of the program delivery. There were significant differences in students' Canadian Achievement Test performance scores prior to the onset of the study. Students in the implicit group attained significantly higher comprehension scores than did students in the explicit group. The results from the program sessions indicated no significant differences in reading comprehension between the implicit and explicit conditions, with the exception of the 6th session involving the reading and interpreting of graphic text. Students in the explicit group performed significantly better when reading and interpreting graphic text than those in the implicit group. No significant differences were evident between the two study conditions across the three summative tests. Upon completion of the study, the results from the Canadian Achievement Test indicated no significant differences in performance between the two study conditions. The findings from this study reveal the effectiveness of providing students with explicit strategy instruction when reading and responding to various forms of text. Modelling the appropriate reading comprehension strategies and test taking skills enabled students to apply the same thought processes to their own independent work. This form of instruction enabled students in the explicit group to improve in their abilities to comprehend and respond to text and therefore should be incorporated as an effective form of classroom teaching.

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The present thesis study is a systematic investigation of information processing at sleep onset, using auditory event-related potentials (ERPs) as a test of the neurocognitive model of insomnia. Insomnia is an extremely prevalent disorder in society resulting in problems with daytime functioning (e.g., memory, concentration, job performance, mood, job and driving safety). Various models have been put forth in an effort to better understand the etiology and pathophysiology of this disorder. One of the newer models, the neurocognitive model of insomnia, suggests that chronic insomnia occurs through conditioned central nervous system arousal. This arousal is reflected through increased information processing which may interfere with sleep initiation or maintenance. The present thesis employed event-related potentials as a direct method to test information processing during the sleep-onset period. Thirteen poor sleepers with sleep-onset insomnia and 1 2 good sleepers participated in the present study. All poor sleepers met the diagnostic criteria for psychophysiological insomnia and had a complaint of problems with sleep initiation. All good sleepers reported no trouble sleeping and no excessive daytime sleepiness. Good and poor sleepers spent two nights at the Brock University Sleep Research Laboratory. The first night was used to screen for sleep disorders; the second night was used to investigate information processing during the sleep-onset period. Both groups underwent a repeated sleep-onsets task during which an auditory oddball paradigm was delivered. Participants signalled detection of a higher pitch target tone with a button press as they fell asleep. In addition, waking alert ERPs were recorded 1 hour before and after sleep on both Nights 1 and 2.As predicted by the neurocognitive model of insomnia, increased CNS activity was found in the poor sleepers; this was reflected by their smaller amplitude P2 component seen during wake of the sleep-onset period. Unlike the P2 component, the Nl, N350, and P300 did not vary between the groups. The smaller P2 seen in our poor sleepers indicates that they have a deficit in the sleep initiation processes. Specifically, poor sleepers do not disengage their attention from the outside environment to the same extent as good sleepers during the sleep-onset period. The lack of findings for the N350 suggest that this sleep component may be intact in those with insomnia and that it is the waking components (i.e., Nl, P2) that may be leading to the deficit in sleep initiation. Further, it may be that the mechanism responsible for the disruption of sleep initiation in the poor sleepers is most reflected by the P2 component. Future research investigating ERPs in insomnia should focus on the identification of the components most sensitive to sleep disruption. As well, methods should be developed in order to more clearly identify the various types of insomnia populations in research contexts (e.g., psychophysiological vs. sleep-state misperception) and the various individual (personality characteristics, motivation) and environmental factors (arousal-related variables) that influence particular ERP components. Insomnia has serious consequences for health, safety, and daytime functioning, thus research efforts should continue in order to help alleviate this highly prevalent condition.

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This study examined the bee fauna of the Carolinian Zone in Ontario, Canada. In 2003, 15687 individuals from 152 species of bees were collected. Tliere were many rare species but few abundant species. There were three distinct bee seasons. The Niagara bee assemblage was less diverse compared to other Carolinian Zone assemblages and types of landscapes. This study also examined how anthropogenic disturbance affects the diversity of bee assemblages. The intermediate disturbance hypothesis (IDH) was tested by selecting field sites subject to low, intermediate, and high disturbance. Intermediate disturbance had the highest species richness (SR=1 15) and most bees (N=556I), followed by low disturbance (SR= 100, N=2975), then high disturbance (SR=72, N=1364), supporting the IDH. Increased species richness in areas of intermediate disturbance was due to higher abundance, possibly because more blooming flowers were found there. Bees were larger in high disturbance areas but smaller in areas of high and intermediate disturbance.

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One hundred and seventy-two subj ects participated in this quantitative, correlational survey which tested Hackman and Oldham's Job Characteristics Model in an educational setting. Subjects were Teaching Masters, Chairmen and Deans from an Ontario community college. The data were collected via mailed questionnaire, on all variables of the model. Several reliable, valid instruments were used to test the variables. Data analysis through Pearson correlation and stepwise multiple regression analyses revealed that core job characteristics predicted certain critical psychological states and that these critical psychological states, in turn were able to predict various personal and work outcomes but not absenteeism. The context variable, Satisfaction with Co-workers, was the only consistent moderating variable between core characteristics and critical psychological states; however, individual employee differences did moderate the relationship between critical psychological states and all of the personal and work outcomes except Internal Work Motivation. Two other moderator variables, Satisfaction with Context and Growth Need Strength, demonstrated an ability to predict the outcome General Job Satisfaction. The research suggests that this model may be used for job design and redesign purposes within the community college setting.

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A class of twenty-two grade one children was tested to determine their reading levels using the Stanford Diagnostic Reading Achievement Test. Based on these results and teacher input the students were paired according to reading ability. The students ages ranged from six years four months to seven years four months at the commencement of the study. Eleven children were assigned to the language experience group and their partners became the text group. Each member of the language experience group generated a list of eight to be learned words. The treatment consisted of exposing the student to a given word three times per session for ten sessions, over a period of five days. The dependent variables consisted of word identification speed, word identification accuracy, and word recognition accuracy. Each member of the text group followed the same procedure using his/her partner's list of words. Upon completion of this training, the entire process was repeated with members of the text group from the first part becoming members of the language experience group and vice versa. The results suggest that generally speaking language experience words are identified faster than text words but that there is no difference in the rate at which these words are learned. Language experience words may be identified faster because the auditory-semantic information is more readily available in them than in text words. The rate of learning in both types of words, however, may be dictated by the orthography of the to be learned word.

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The purpose of this research study was to determine whether or not the use of a single day of Personal Wellness Evaluations would be meaningful enough to change the attitudes of participants toward adopting a healthier lifestyle, or if it was necessary to include regular planned health counselling alon-g with the Personal Wellness Evaluations in order to'observe changes in beliefs, attitudes and behaviours toward active living and the adoption of a healthier lifestyle. Attitudes and behaviours toward physical fitness and healthy lifestyle choices were assessed through a questionnaire composed of the following instruments: Fishbein and Ajzen Attitude and Behaviour Questionnaire, Leisure Behaviour Questionnaire, Ten Centimeter Bipolar Health Continuum, Neugarten Life Satisfaction Assessment, Job Description Index, Selected questions from the Ontario Health Survey, and the Symptom Reporting Questionnaire. Physical fitness evaluation consisted of the Canadian Standardized Test of Fitness, measures of blood pressure, and total cholesterol. The participants were divided into three groups: Group 1- CSTF & health counselling, Group 2- CSTF only, and Group 3- a control group. All three groups received the questionnaire both at the beginning and at the end of the study. Group 1 and Group 2 also participated in fitness testing at these same times, with a three-month time interval between test times. Group 1 also received weekly one-hour health education sessions during the three months between fitness testing. While there were some differences found between the three groups in this study, the results of this study suggested that this three-month workplace wellness program had no impact on the participants' attitudes and behaviours toward health and physical activity. There were no significant differences in the physical fitness measures between Group 1 and Group 2 , nor in the participants' questionnaire responses. These results may be due to the participants' lack of compliance to this wellness program. Employees who 11 participate in a workplace weIlness program must be self-motivated to comply with the program in order to receive the full benefits the program has to offer. Some participants in this study did not have the internal motivation necessary to remain in the study for the three-month period. Future research may consider implementing a workplace wellness program for a longer duration as well as incorporating a specific physical fitness program for the participants to follow. An exercise program could improve the participants' physical fitness, while the health counselling would give the individuals the health education necessary to lead a healthy lifestyle.

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The purpose of this study was to investigate Howard Gardner's (1983) Multiple Intelligences theory, which proposes that there are eight independent intelligences: Linguistic, Spatial, Logical/Mathematical, Interpersonal, Intrapersonal, Naturalistic, Bodily-Kinesthetic, and Musical. To explore Gardner's theory, two measures of each ability area were administered to 200 participants. Each participant also completed a measure of general cognitive ability, a personality inventory, an ability self-rating scale, and an ability self-report questionnaire. Nonverbal measures were included for most intelligence domains, and a wide range of content was sampled in Gardner's domains. Results showed that all tests of purely cognitive abilities were significantly correlated with the measure of general cognitive ability, whereas Musical, Bodily-Kinesthetic, and one of the Intrapersonal measures were not. Contrary to what Multiple Intelligences theory would seem to predict, correlations among the tests revealed a positive manifold and factor analysis indicated a large factor of general intelligence, with a mathematical reasoning test and a classification task from the Naturalistic domain having the highest ^- loadings. There were only minor sex differences in performance on the ability tests. Participants' self-estimates of ability were significantly and positively correlated with actual performance in some, but not all, intelligences. With regard to personality, a hypothesized association between Openness to Experience and crystallized intelligence was supported. The implications of the findings in regards to the nature of mental abilities were discussed, and recommendations for further research were made.

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Multiple measures have been devised by clinicians and theorists from many different backgrounds for the purpose of assessing the influence of the frontal lobes on behaviour. Some utilize self-report measures to investigate behavioural characteristics such as risktaking, sensation seeking, impulsivity, and sensitivity to reward and punishment in an attempt to understand complex human decision making. Others rely more on neuroimaging and electrophysiological investigation involving experimental tasks thought to demonstrate executive functions in action, while other researchers prefer to study clinical populations with selective damage. Neuropsychological models of frontal lobe functioning have led to a greater appreciation of the dissociations among various aspects of prefrontal cortex function. This thesis involves (1) an examination of various psychometric and experimental indices of executive functions for coherence as one would predict on the basis of highly developed neurophysiological models of prefrontal function, particularly those aspects of executive function that involve predominantly cognitive abilities versus processes characterized by affect regulation; and (2) investigation of the relations between risk-taking, attentional abilties and their associated characteristics using a neurophysiological model of prefrontal functions addressed in (1). Late adolescence is a stage in which the prefrontal cortices undergo intensive structural and functional maturational changes; this period also involves increases in levels of risky and sensation driven behaviours, as well as a hypersensitivity to reward and a reduction in inhibition. Consequently, late adolescence spears to represent an ideal developmental period in which to examine these decision-making behaviours due to the maximum variability of behavioural characteristics of interest. Participants were 45 male undergraduate 18- to 19-year olds, who completed a battery of measures that included self-report, experimental and behavioural measures designed to assess particular aspects of prefrontal and executive functioning. As predicted, factor analysis supported the grouping of executive process by type (either primarily cognitive or affective), conforming to the orbitofrontal versus dorsolateral typology; risk-taking and associated characteristics were associated more with the orbitofrontal than the dorsolateral factor, whereas attentional and planning abilities tended to correlate more strongly with the dorsolateral factor. Results are discussed in light of future assessment, investigation and understanding of complex human decision-making and executive functions. Implications, applications and suggestions for future research are also proposed.

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To date there is no documented procedure to extrapolate findings of an isometric nature to a whole body performance setting. The purpose of this study was to quantify the reliability of perceived exertion to control neuromuscular output during an isometric contraction. 21 varsity athletes completed a maximal voluntary contraction and a 2 min constant force contraction at both the start and end of the study. Between pre and post testing all participants completed a 2 min constant perceived exertion contraction once a day for 4 days. Intra-class correlation coefficient (R=O.949) and standard error of measurement (SEM=5.12 Nm) concluded that the isometric contraction was reliable. Limits of agreement demonstrated only moderate initial reliability, yet with smaller limits towards the end of 4 training sessions. In conclusion, athlete's na"ive to a constant effort isometric contraction will produce reliable and acceptably stable results after 1 familiarization sessions has been completed.

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The present research focused on the pathways through which the symptoms of posttraumatic stress disorder (PTSD) may negatively impact intimacy. Previous research has confirmed a link between self-reported PTSD symptoms and intimacy; however, a thorough examination of mediating paths, partner effects, and secondary traumatization has not yet been realized. With a sample of 297 heterosexual couples, intraindividual and dyadic models were developed to explain the relationships between PTSD symptoms and intimacy in the context of interdependence theory, attachment theory, and models of selfpreservation (e.g., fight-or-flight). The current study replicated the findings of others and has supported a process in which affective (alexithymia, negative affect, positive affect) and communication (demand-withdraw behaviour, self-concealment, and constructive communication) pathways mediate the intraindividual and dyadic relationships between PTSD symptoms and intimacy. Moreover, it also found that the PTSD symptoms of each partner were significantly related; however, this was only the case for those dyads in which the partners had disclosed most everything about their traumatic experiences. As such, secondary traumatization was supported. Finally, although the overall pattern of results suggest a total negative effect of PTSD symptoms on intimacy, a sex difference was evident such that the direct effect of the woman's PTSD symptoms were positively associated with both her and her partner's intimacy. I t is possible that the Tend-andBefriend model of threat response, wherein women are said to foster social bonds in the face of distress, may account for this sex difference. Overall, however, it is clear that PTSD symptoms were negatively associated with relationship quality and attention to this impact in the development of diagnostic criteria and treatment protocols is necessary.

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The primary objectives of the present study were 1) to examine the relationship between health-enhancing physical activity (HEPA) and well-being across the previous day and 2) to examine the role of basic psychological need satisfaction as a potential mediator of the HEPA – well-being relationship. Participants (N = 203) were a convenience sample of undergraduate students with data collected cross sectionally. HEPA was generally associated with well-being (r‟s ranged from .18 to .62). Multiple mediation analyses supported psychological need satisfaction as mechanisms underpinning the HEPA – well- being relationship. Subsequent analyses demonstrated that effort put forth in HEPA activities, as opposed to frequency or duration, uniquely predicted well-being. The role of effort was further highlighted in the multiple mediation analyses. As such future research may wish to investigate the utility of a HEPA program that facilitates effortful engagement and fulfillment of basic psychological needs.