2 resultados para Universidad de Puerto Rico

em Digital Commons - Michigan Tech


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This thesis is a study of the gender relations of the residents of Aguirre, Puerto Rico, between 1940 and 1991. The primary goal of the project was to explore how gender roles and relations in the Aguirre community were impacted by the social class system introduced by the Aguirre Sugar Company. This project was based on the interpretation of the past and present situation of the Aguirre community using oral history, by conducting a series of interviews among its residents. The interviews resulted in three main themes. First, the concepts of `normal and natural' were used to distinguish gender roles. Second, Aguirreños identified `family as community', since through the family individuals built their gender identity and learned the basic rules of coexistence within the social hierarchy of the community. Third, although the gender and class roles were clear in the community, `resistance and negotiation' occurred in the home and at the Company between those of different gender and social classes. The Aguirre Sugar Company was one of the principal influences on the construction of the Aguirreños identity, and left a mark on the past, present and future generations.

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Tropical trees have been shown to be more susceptible to warming compared to temperate species, and have shown growth and photosynthetic declines at elevated temperatures as little as 3oC above ambient. However, regional and global vegetation models lack the data needed to accurately represent physiological response to increased temperatures in tropical forests. We compared the instantaneous photosynthetic responses to elevated temperatures of four mature tropical rainforest tree species in Puerto Rico and the temperate broadleaf species sugar maple (Acer saccharum) in Michigan. Contrary to expectations, leaves in the upper canopy of both temperate and tropical forests had temperature optima that are already exceeded by mean daily leaf temperatures. This indicates that tropical and temperate forests are already seeing photosynthesis decline at mid-day temperature. This decline may worsen as air temperatures rise with climate change if trees are unable to acclimate, increasing the likelihood that forests may shift from carbon sinks to sources. A secondary study was conducted on experimentally warmed sugar maple seedlings to determine if photosynthesis had been able to acclimate to +5oC air temperature over four years. Species abundance models had predicted a decline of sugar maple within the Upper Peninsula of Michigan over the next 100 years, due to elevated temperature and altered precipitation. Instantaneous photosynthetic temperature response curves on both control and heated seedlings showed that the differences between treatments were not statistically significant, though there was a 16% increase in temperature optima and a 3% increase in maximum rates of photosynthesis in warmed plots. Though evidence of acclimation was not significant, the seedlings did not fare poorly as the models suggest.