Orientador: Regina Celia Spadari / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-14T00:03:56Z (GMT). No. of bitstreams: 1 Martins_MarliCardoso_M.pdf: 3221775 bytes, checksum: 809e499c474fa4c62483d771cca4381d (MD5) Previous issue date: 1991 / Resumo: Estudos prévios demonstraram que átrios direitos isolados de ratos submetidos ao "stress" apresentam alterações de sensibilidade ao efeito cronotrópico das catecolaminas. Os objetivos deste trabalho são: avaliar a possibilidade de uitilização da técnica de registro da pressão arterial em ratos não anestesiados, para a análise das respostas cronotrópica e pressórica às catecolaminas; descrever as alterações de sensibilidade cardiovascular às catecolaminas em ratos submetidos ao "stress"; caracterizar a participação dos diferentes tipos de adrenoceptores nestas alterações; comparar as alterações observadas "in vivo" com aquelas anteriormente descritas em átrios direitos isolados de ratos submetidos ao "stress". Utilizamos ratos machos, adultos, Wistar. Sob anestesia por éter, as artérias e veias femurais esquerdas de cada animal foram canuladas 24s antes do experimento. O registro da pressão arterial foi obtido conectando-se a cânula arterial a um transdutor de pressão, enquanto o animal permanecia em sua própria gaiola, não anestesiado. A administração dos diferentes farmacos foi realizada através da cânula venosa. Os animais do grupo experimental foram submetidos a 50 min. de natação... O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Not informed. / Mestrado / Fisiologia / Mestre em Ciências Biológicas

Objective: This study reports the stress related causes of presenteeism amongst South African managers, including the opportunities and challenges of affirmative action. Methods: Data were obtained through the use of a questionnaire administered to all managers in two companies situated in the Gauteng region of South Africa. The survey incorporated the COPSOQ stress scales, Stanford Presenteeism Scale (SPS-6), and an affirmative action scale. Results: Seventy-three percent (62) of the managers responded. Cronbach’s alpha for all scales indicates adequate reliability. There were significant differences in levels of stress between South African managers and those in other countries. High levels of stress are associated with decreased presenteeism. There were significant differences in the means between black and white managers in relation to affirmative action in the South African work environment. Conclusions: Black managers appear to be alienated from feeling responsible for productivity, while white managers appear to work under fear-based motivation due to affirmative action measures imposed in the workplace. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

The aim of the study was to understand the meaning of stress, and towards this end eleven individuals who claimed to have experienced the phenomenon during the six months prior to data collection were asked to describe their experience. These transcribed protocols were explicated in terms of a phenomenological praxis, and the emotional content of descriptions subjected to taxonomic analysis. In addition, a literature review for the purposes of tracing the development of contemporary stress models and related constructs was conducted. The latter critiqued current conceptualisations of stress, and attempted to highlight some important contributions. Explication in terms of phenomenological praxis identified seven central features associated with lived stress, namely, lived stress as : the perception of personal cost; a sense of entrapment; persistent coping efforts; learned helplessness; embodiment; and, poor social relations. In addition, the unfolding nature of the experience suggested stress as a continuous process of adjustment to worldly demands, and furthermore, highliJhted several variations of structure. The latter themes were used to develop a more inclusive model of lived stress as a dynamic and unfolding process. Dialogue with existing literature was able to confirm the self-world split proposed by the transactional approach to stress as legitimate, and furthermore, confirmed the primacy of cognition for the stress phenomenon. In addition, the link between stress and personality factors, psychopathological conditions and related fields of enquiry (such as anxiety and burnout) as well as more positive modes of being (such as creativity) were discussed. Furthermore, lived stress was shown to involve a threat to the individual's continued existence, both with respect to his/her the desired self and its unfolding and his/her physicality, while the presence of mutual hostility between self and world was also noted. The study concludes with reflection concerning the methodologies employed, and suggests that while qualitative and interpretive methods are both cumbersome and time consuming if rigorously applied, they do enrich the understanding of complex experiential phenomena. Finally, several suggestions are made for further research and refinement in the stress field, the most pertinent of which appears to be that of establishing the relationship between lived stress and the development of more debilitating psychopathological conditions.

An analytic solution to a particular boundary value problem in linear elasticity is presented. The problem considered is that of a circular disc, in plane strain or generalized plane stress, which is loaded quite generally at the perimeter by a set of self equilibrating forces. The disc has a radial crack extending completely from the centre to the perimeter. Three particular load cases are considered: the disc is loaded by uniform radial tension; the disc is pulled by two diametrical concentrated loads with line of action perpendicular to the crack; the disc is pulled by two concentrated forces acting at the mouth of the crack. In each case the stress intensity factor is evaluated and contours of the isochromatics are presented in dimensionless form. The results agree with those derived by other workers but the method presented here is more general, more efficient, and extends the previous results for finite bodies containing cracks. The three load cases have also been applied to the disc when the tip of the crack has been removed by the presence of a concentric hole. New results are presented for the stress concentration factors for a full range of geometric parameters. Finally it is shown how the second and third of the load cases may be used for controlled laboratory tests in the study of fracture and fracture toughness of brittle materials. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Recent studies have implicated acute reactivity to a psychological stressor as a potential marker in the pathogenesis of cardiovascular disorders. However, only very few well controlled prospective studies necessary to confirm this hypothesis have been conducted. Such studies would need to demonstrate that cardiovascular hyperreactivity is a stable, individual-specific predisposition which is not significantly affected by response habituation to repeated stressor exposures. In the present study the relationship between degree of cardiovascular responsiveness and response habituation as a function of number of stressor repetitions and length of interstressor interval was assessed. Responses to a mental arithmetic task were compared within trials (3 minutes), across trials (3 per session), and across experimental sessions (2 sessions with a 4-week interval) in high versus low cardio-reactive women. Ninety female, normotensive subjects (mean age 24.6 years) participated in the study. Subjects were randomly assigned to one of two experimental conditions: in Condition 1 (repeated exposure) a twenty minute adaptation period was followed by a series of three, 3 minute mental arithmetic tasks with a 90 db white noise interference during the first laboratory session. A three minute rest period followed each task period. Subjects in Condition 2 (single exposure) completed the twenty-minute adaptation period followed by a single 3-minute task and a subsequent fifteen-minute recovery period. During their second visit all subjects completed a series of three mental arithmetic tasks identical to those completed in Condition 1, visit 1. Throughout the experimental sessions heart rate (HR), systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP) were monitored at one minute intervals using an automated, digital Dinamap 845 Vital Signs Monitor. Subjects were classified into heart rate and SBP reactivity terciles on the basis of their response to the first stress task in the initial session. Only those subjects who fell into the lowest and highest reactivity terciles were included in subsequent analyses. Given that not all subjects received all trials three sets of analyses of covariance were necessary to fully examine the 2 (low versus high reactivity) X 2 (conditions) X 2 (visits) X 3 (trials) X 3 (minutes per trial) repeated measures factorial design. Age and respective baselines were employed as covariates. The results consistently indicated main effects (p < .001) for the reactivity groups, visits, trials, and minutes factors on each of the four dependent measures. These findings together with the results of subsequent trend analyses and Newman-Keuls post-hoc tests identified significant decreases in response levels within trials, across trials, and across the two experimental sessions. Decreases from minute 1 to minute 2 of each trial were greater than those from minute 2 to minute 3 on heart rate measures. The same pattern of decreases was observed for the trials factor. Blood pressure responses showed a delayed onset of decreases in response magnitude within experimental trials. All blood pressure measures showed evidence of response decreases from minute 2 to minute 3 of each trial. High reactors showed greater decreases in responses than low reactors across the experimental sessions. For the final stress task the HR, DBP and MAP responses of the high reactivity groups in the repeated stressor condition could not be discriminated from those of the low reactors. The notion of within-individual response specificity and the use of acute cardiovascular reactivity as both a classification and an outcome measure may therefore need to be re-evaluated. / Arts, Faculty of / Psychology, Department of / Graduate

This dissertation reports an evaluation of Self-instructional training as a stress-management technique for multi-problem clients. Individuals who responded to a newspaper advertisement offering assistance in tension management and who reported that they experienced anxiety in at least two relatively specific situations were assigned to the following treatment conditions: (1) Self-instructional training (n=ll), (2) Awareness (n=ll), (3) Skills training (n=ll) and (4) Minimal treatment control (n=9). Therapy was conducted over a six-week period with therapists in the first three experimental conditions meeting small groups for 1%-hour sessions. Clients in all conditions were encouraged to adopt a situational view of anxiety and to record the details of the stressful situations they encountered throughout the course of treatment. In the first condition, Meichenbaum's (1974) treatment manual was used as a guide. Clients were taught to analyze their problems according to a cognitive model of anxiety and to adopt the use of coping self-statements in stressful situations. Clients in condition two received a similar treatment rationale, but did not specifically practice the use of coping self-statements. The third condition provided a combination of role-playing and coaching to assist clients to change their behavior in stressful situations. Finally the minimal treatment group attended a two-hour session in which the self-instructional training procedure was explained to them and was applied to some of their problems. Analysis of self- and Significant Other reports found no significant differences among treatment conditions, although there was significant change on almost all measures for the client sample as a whole. These inconclusive findings were discussed in relation to differences between the present client sample and clients who have served as subjects in previous research. It was suggested that a promising area for future research might be the investigation of the role of certain client characteristics in determining treatment outcome, especially levels of trait anxiety and the duration and specificity of stressful situations. / Arts, Faculty of / Psychology, Department of / Graduate

The purpose of this study was to examine whether or not self-monitoring of stressors and physiological response to stressors enhances the effectiveness of a stress management technique, specifically relaxation training. The primary hypothesis which stated that the RSMS group would experience a greater reduction in depression (on the Beck Depression Inventory), and enhancement in self-efficacy (on the General Self-efficacy Scale) than all other groups, was not supported.

I develop and test a theoretical model to examine how and why transformational leadership affects employees’ appraisals of challenge and hindrance stressors. I draw on the transactional theory of stress to argue that transformational leaders motivate their employees to believe that they can successfully cope with workplace stressors, which in turn encourages them to appraise challenge stressors more positively and hindrance stressors as less threatening. Presenting a parallel mediation model, I test three mediators that operationalize my underlying theory: psychological empowerment; psychological safety; and stress mindsets. I conduct a time-separated online survey study of 255 employed adults. I test my theory through two sets of analyses, considering two sets of dependent variables: (1) appraisals of stressors in general and (2) appraisals of stressors in the context of hypothetical workplace vignettes. My results suggest that (1) transformational leadership was positively associated with challenge appraisals in the context of challenge and hindrance stressors, and negatively associated with hindrance appraisals in the context of challenge and hindrance stressors. Psychological empowerment, but not psychological safety nor stress mindset, was a significant mediator in all cases. (2) Results of the vignette analysis found that transformational leadership was positively associated with challenge appraisals and negatively associated with hindrance appraisals of both challenge and stressor vignettes. However, none of the mediators were significant. I conclude that transformational leaders can help employees appraise stressors more optimistically by empowering them to view themselves as competent and in control in relation to their work. The applications of my research to theory and practice are discussed.

Aim Stress among healthcare workers (HCWs) working with HIV/AIDS patients is an important deterrent to provision of services to HIV patients. The main aim of this study was to determine the prevalence of stress levels among HCWs in Polokwane Municipality HIV clinics. Method Forty-four HCWs in four different clinics completed a self administered questionnaire. Questionnaire consisted of demographic info, the Maslach Burnout Inventory, the AIDS Stress scale and the stressors and rewards of HIV/AIDS work. Results The majority of the healthcare workers (HCWs) in this study were female (77%) and married (64%). The biggest professional group were nurses (46%) followed by lay counsellors (25%). The mean age of the HCWs was 39. The results of this study revealed that half of the respondents (52%) had high level of emotional exhaustion and depersonalization. A total of 27% of HCWs had moderate to severe AIDS stress as measured by AIDS Stress Scale. An overwhelming majority (95%) of HCWs reported that they enjoy their work with HIV/AIDS patients. Conclusion Despite the high levels of burnout, the majority of HCWs in the HIV clinics find HIV/AIDS work rewarding. Workplace related stressors rather than the actual work with HIV/AIDS patients is a major source of stress.

Channel catfish (Ictalurus punctatus) are important to aquaculture and natural ecosystems, however little is known regarding effects of high summer temperatures, which are predicted to increase with climate change. Therefore, two studies were conducted to examine physiological effects of high temperatures on juvenile channel catfish. The first examined effects of three cycling thermal regimes (23-27°C, 27-31°C, and 31-35°C) characteristic of culture environments in Mississippi on growth, food consumption, feed conversion ratio, specific growth rate, and activity. The second study measured active and resting metabolic rates and swimming endurance at constant temperatures (27, 31, and 35°C). The best growth and feed conversion occurred at 27-31°C and activity was greatest at 31-35°C. Active metabolism and swimming endurance decreased at 35°C. These results indicate high summer temperatures reduce food consumption, increase activity, impair metabolism and endurance, and therefore present challenges to the culture and management of channel catfish.