2 resultados para Exchanges

em Digital Commons at Florida International University


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The subject-matter of this dissertation is the social construction of economic exchanges, with an emphasis on market transactions. Applying a Weberian approach, the dissertation analyzes the social construction of economic exchanges at the following analytical levels: the agency-level, the institutional-structural level and the comparative-historical level. At the agency-level, the dissertation explores the role that human actors and social actions play in economic exchanges, especially market transactions. Theoretically elaborated and empirically examined is the assumption of market-economic exchanges as particular types of social action. At the institutional-structural level, the dissertation examines the relations of society and culture to market-economic exchanges. The assumption that the market economy is situated in and influenced by a broader social-cultural framework is advanced and evaluated in light of empirical findings. At the comparative-historical level, the dissertation engages in an analysis of the social construction of economic exchanges across various societies and over time. The assumption of the historical specificity of the market economy is reexamined, and the social construction of economic exchanges in traditional, capitalist and post-socialist societies is subject to comparative investigation. In the conclusion, further theoretical, methodological and empirical implications as well as directions for future analyses are discussed. ^

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We report on net ecosystem production (NEP) and key environmental controls on net ecosystem exchange (NEE) of carbon dioxide (CO2) between a mangrove forest and the atmosphere in the coastal Florida Everglades. An eddy covariance system deployed above the canopy was used to determine NEE during January 2004 through August 2005. Maximum daytime NEE ranged from −20 to −25 mmol (CO2) m−2 s−1 between March and May. Respiration (Rd) was highly variable (2.81 ± 2.41 mmol (CO2) m−2 s−1), reaching peak values during the summer wet season. During the winter dry season, forest CO2 assimilation increased with the proportion of diffuse solar irradiance in response to greater radiative transfer in the forest canopy. Surface water salinity and tidal activity were also important controls on NEE. Daily light use efficiency was reduced at high (>34 parts per thousand (ppt)) compared to low (ppt) salinity by 46%. Tidal inundation lowered daytime Rd by ∼0.9 mmol (CO2) m−2 s−1 and nighttime Rd by ∼0.5 mmol (CO2) m−2 s−1. The forest was a sink for atmospheric CO2, with an annual NEP of 1170 ± 127 g C m−2 during 2004. This unusually high NEP was attributed to year‐round productivity and low ecosystem respiration which reached a maximum of only 3 g C m−2 d−1. Tidal export of dissolved inorganic carbon derived from belowground respiration likely lowered the estimates of mangrove forest respiration. These results suggest that carbon balance in mangrove coastal systems will change in response to variable salinity and inundation patterns, possibly resulting from secular sea level rise and climate change. Citation: Barr, J. G., V. Engel, J. D. Fuentes,