Made available in DSpace on 2014-12-17T14:33:11Z (GMT). No. of bitstreams: 1 AngelicaNSB_DISSERT.pdf: 1338849 bytes, checksum: e892c51257539cf2057935e233971d4c (MD5) Previous issue date: 2013-07-16 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Many prey organisms change their phenotype to reduce the predation risk. However, such changes are associated with trade-offs, and can have negative effects on prey growth or reproduction. Understand how preys assess the predation risk is essential to evaluate the adaptive value of predator-induced phenotypic and its ecological consequences. In this study, we performed a mesocosm experiment to test: i) if growth and stoichiometry of Lithobates catesbeianus tadpoles is altered in response to giant water bug presence (Belostoma spp.); ii) if these responses depend on tadpoles density in environment. Here, we show that tadpoles growth and stoichiometry are not changed by predator presence, neither in low nor in high densities. Our results suggest that tadpoles exposed to predation risk regulate their physiology to preserve the elemental stoichiometric homeostase of their body and excretion. Further, point out to need for future studies that elucidate under what conditions growth and stoichiometry are changed in response to predation risk / Muitos organismos alteram o seu fen?tipo para reduzir o risco de preda??o. No entanto, tais modifica??es est?o associadas a trade-offs, que podem ter efeitos negativos sobre o crescimento e a reprodu??o destes organismos. Compreender como as presas avaliam o risco de preda??o ? fundamental para avaliar o valor adaptativo das mudan?as fenot?picas induzidas pelo predador e suas consequ?ncias ecol?gicas. Neste estudo n?s realizamos um experimento em mesocosmo para testar: i) se o crescimento e a estequiometria dos girinos da esp?cie Lithobates catesbeianus ? alterado em resposta a presen?a de baratas d ?gua predadoras (Belostoma spp.); ii) se estas respostas dependem da densidade de girinos no ambiente. Aqui n?s mostramos que os girinos n?o t?m o seu crescimento nem a sua estequiometria afetada pela presen?a do predador, esteja os girinos em baixas ou em altas densidades. Nossos resultados indicam que os girinos expostos ao risco de preda??o regularam sua fisiologia a fim de preservar a homeostase estequiom?trica do seu corpo e excretas. Al?m disso, aponta a necessidade de experimentos que elucidem em que condi??es o crescimento e a estequiometria de girinos s?o modificados em resposta ao risco de preda??o

Individual distress in the work-place has been cited as the cause of enormous loss of productivity and income, and has therefore attracted much attention from researchers and therapists alike. However, an extensive literature study reveals that in the field of work-related distress and its management, there appears to be discontinuity, a diversity of opinion and even confusion with regard to definitions, causes and possible remedies for the problem. It is suggested that this situation has been brought about and is being perpetuated by the Newtonian/Cartesian epistemological foundation on which most thinking in the field is based. It is further suggested that an epistemology informed by ecosystemic, constructivist principles could facilitate a way of thinking which would be more useful in this context. A case study was done in accordance with the above-mentioned ideas, which served as an investigation of their usefulness in a situation of reported work-related stress. On the basis of the information which emerged from the study, it is concluded that an ecosystemic approach can indeed provide a useful basis for understanding such situations. Furthermore, it is suggested that there are certain commonalities between such situations which are primarily founded in contexts in which the individual finds himself faced with contradictory demands which are not acknowledged as such. Finally, the point is made that if, in accordance with a constructivist viewpoint, "stress" is understood to be a social construction rather than an absolute condition, then the traditional way of thinking provides us with descriptions of man, society and the relationship between them, which are negative and may also be reflexively destructive. However, since constructivism allows for a different construction to be brought forth, we may utilise ecosystemic thinking to provide a more optimistic view. / Psychology / D. Litt. et Phil. (Psychology)

Individual distress in the work-place has been cited as the cause of enormous loss of productivity and income, and has therefore attracted much attention from researchers and therapists alike. However, an extensive literature study reveals that in the field of work-related distress and its management, there appears to be discontinuity, a diversity of opinion and even confusion with regard to definitions, causes and possible remedies for the problem. It is suggested that this situation has been brought about and is being perpetuated by the Newtonian/Cartesian epistemological foundation on which most thinking in the field is based. It is further suggested that an epistemology informed by ecosystemic, constructivist principles could facilitate a way of thinking which would be more useful in this context. A case study was done in accordance with the above-mentioned ideas, which served as an investigation of their usefulness in a situation of reported work-related stress. On the basis of the information which emerged from the study, it is concluded that an ecosystemic approach can indeed provide a useful basis for understanding such situations. Furthermore, it is suggested that there are certain commonalities between such situations which are primarily founded in contexts in which the individual finds himself faced with contradictory demands which are not acknowledged as such. Finally, the point is made that if, in accordance with a constructivist viewpoint, "stress" is understood to be a social construction rather than an absolute condition, then the traditional way of thinking provides us with descriptions of man, society and the relationship between them, which are negative and may also be reflexively destructive. However, since constructivism allows for a different construction to be brought forth, we may utilise ecosystemic thinking to provide a more optimistic view. / Psychology / D. Litt. et Phil. (Psychology)