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The photosynthetic acclimation of Lolium perenne in response to three years growth in a free-air CO{sub 2} enrichment (FACE) system

Description: Pure stands of Ryegrass were in their third year of growth in the field, exposed to either ambient (355 {mu}mol mol{sup -1}), or elevated (600 {mu}mol mol{sup -1}) atmospheric CO{sub 2} concentration. A Free-Air CO{sub 2} Enrichment (FACE) system was used to maintain the elevated CO{sub 2} concentration whilst limiting experimental constraints on the field conditions. The theoretically predicted increase in the net rates of CO{sub 2} uptake per unit leaf area (A {mu}mol mol{sup -1}) as a consequence, primarily, of the suppression of photorespiration by CO{sub 2} a competitive inhibitor of RubP oxygenation by Rubisco, was observed for the Lolium perenne studied. Also observed was a general decline in leaf evapotranspiration (E) consistent with observations of increased water use efficiency of crops grown in elevated CO{sub 2}. Enhancement of leaf A in the FACE grown L. perenne ranged from 26.5 1 % to 44.95% over the course of a diurnal set of measurements. Whilst reductions in leaf E reached a maximum of 16.61% over the same diurnal course of-measurements. The increase in A was reconciled with an absence of the commonly observed decline in V{sub c}{sub max} as a measure of the maximum in vivo carboxylation capacity of the primary carboxylasing enzyme Rubisco and J{sub max} a measure of the maximum rate of electron transport. The manipulation of the source sink balance of the crop, stage of canopy regrowth or height in the canopy had no effect on the observation of a lack of response. The findings of this study will be interpreted with respect to the long term implications of C{sub 3} crops being able to adapt physiologically to maximize the potential benefits conferred by growth in elevated CO{sub 2}.
Date: August 1, 1996
Creator: Hymus, G.J.
Partner: UNT Libraries Government Documents Department

Inter and intra-specific variation in photosynthetic acclimation response to long term exposure of elevated carbon dioxide

Description: The response of intra and interspecific variation in photosynthetic acclimation to growth at elevated atmospheric CO{sub 2} concentration (600{micro}mol mol-l) in six important grassland species was investigated. Plants were grown in a background sward of Lolium perenne and measurements were made after four years of growth at elevated C{sub a}. Elevated CO{sub 2} was maintained using a FACE (Free-Air Carbon Enrichment) system. Significant intra and interspecific variation in acclimation response was demonstrated. The response of adaxial and abaxial stomatal conductance to elevated CO{sub 2} was also investigated. The stomatal conductance of both the adaxial and abaxial leaf surfaces was found to be reduced by elevated C{sub a}. Significant asymmetric responses in stomatal conductance was demonstrated in D. glomerata and T. pratense. Analysis of stomatal indices and densities indicated that the observed reductions in stomatal conductance were probably the result of changes in stomatal aperture.
Date: August 1, 1996
Creator: Wilkinson, M.
Partner: UNT Libraries Government Documents Department

Role of HSP100 proteins in plant stress tolerance. Final technical report

Description: This research focused on the following areas: characterization of HSP100 genes and their expression during stress and development; requirement of HSP101 for thermotolerance; thermotolerance of plants over-expressing HSP100; and identifying interacting proteins that functionally interact with HSP104.
Date: August 1, 1998
Creator: Vierling, E.
Partner: UNT Libraries Government Documents Department

The use of the bio-photometer in determining the dark adaptation of pre-school age children

Description: The degree to which the normal eye can adapt to the dark is related to or dependent upon the eye's ability to regenerate visual purple. The relationship of vitamin A to the visual cycle has caused much development in improved methods of detecting vitamin A deficiency. For the most part these methods have been applied to adults and school age children. This study seeks to analyze this method as applied to pre-school age children.
Date: August 1941
Creator: Wright, Mary Lou McCauley
Partner: UNT Libraries

Strengthening Clean Energy Technology Cooperation under the UNFCCC: Steps toward Implementation

Description: Development of a comprehensive and effective global clean technology cooperation framework will require years of experimenting and evaluation with new instruments and institutional arrangements before it is clear what works on which scale and in which region or country. In presenting concrete examples, this paper aims to set the first step in that process by highlighting successful models and innovative approaches that can inform efforts to ramp up clean energy technology cooperation. This paper reviews current mechanisms and international frameworks for global cooperation on clean energy technologies, both within and outside of the UNFCCC, and provides selected concrete options for scaling up global cooperation on clean energy technology RD&D, enabling environment, and financing.
Date: August 1, 2010
Creator: Benioff, R.; de Coninck, H.; Dhar, S.; Hansen, U.; McLaren, J. & Painuly, J.
Partner: UNT Libraries Government Documents Department

Employed Stepmothers: Psychological Stress, Personal Adjustment, Psychological Needs, and Personal Values

Description: Employed and non-employed stepmothers were compared on four psychological dimensions: stress, adjustment, needs, and values. Employed stepmothers were hypothesized to experience greater stress, lower adjustment, different needs, and different values. Racial and race by employment status differences along these four dimensions were also addressed.
Date: August 1983
Creator: Rila, Barbara A. (Barbara Ann)
Partner: UNT Libraries

Buying Time: A User’s Manual for Building Resistance and Resilience to Climate Change in Natural Systems

Description: This publication is meant for Protected Areas Managers. It gives detailed information about assessing occurring and possible damage from climate change and fending off the damage - buying time for our protected areas while the world works out the only long-term solution - reducing CO2 emissions.
Date: August 2003
Creator: Hansen, L. J.; Biringer J.L. & Hoffman J.R.
Partner: UNT Libraries

Root adaptations at stress levels of nitrate, phosphate, or both simultaneously

Description: Sunflowers in flowing hydroponic culture show reduced growth rates at nitrate levels below 10 ..mu..M nitrate or phosphate levels below 0.3 ..mu..F. At least for phosphate, this level is a very small fraction (0.003) of the K/sub m/ for the uptake systems. We have quantified four major adaptations that enable high growth rates under incipient stress: increased root:shoot ratio; increased uptake capacity (V/sub max/) per unit root mass; nocturnal uptake of nutrients; and (only partially adaptive) reduced tissue concentrations of nutrients. We show that capital energy costs (in root growth) for acquiring nutrients can exceed direct or operational costs of internal metabolism (nitrate reduction, e.g.,); this has implications for the plant-controlled trade-off of NO/sub 3//sup -/-NH/sub 4//sup +/ - N/sub 2/ as N sources for legumes and other plant types. We outline needed further research and suggest guidelines for breeding plants for tolerating nutritional stresses; we also suggest that some measures of nutrient-use efficiency may be misleading. 6 references, 2 figures, 2 tables.
Date: August 1, 1984
Creator: Gutschick, V.P. & Kay, L.E.
Partner: UNT Libraries Government Documents Department

Effects of Macrophyte Functional Diversity on Taxonomic and Functional Diversity and Stability of Tropical Floodplain Fish Assemblages

Description: Multiple dimensions of biodiversity within and across producer and consumer guilds in the food web affect an ecosystem’s functionality and stability. Tropical and subtropical aquatic ecosystems, which are extremely diverse, have received much less attention than terrestrial ecosystems in regards to the effects of biodiversity on ecosystem functioning. We conducted a field experiment that tested for effects of macrophyte functional diversity on diversity and stability of associated fish assemblages in floodplain lakes of the Upper Paraná River floodplain, Brazil. Three levels of macrophyte functional diversity were maintained through time in five floodplain lakes and response variables included various components of fish taxonomic and functional diversity and stability. Components of functional diversity of fish assemblages were quantified using a suite of ecomorphological traits that relate to foraging and habitat use. Response variables primarily distinguished macrophyte treatments from the control. Macrophyte treatments had, on average, double the number of species and total abundance than the control treatment, but only limited effects on stability. The high diversity treatment was essentially nested within the low diversity for assemblage structure and had similar or even slightly lower levels of species richness and abundance in most cases. Gymnotiformes and young-of-year were diverse and relatively abundant in macrophyte treatments contributing to the large differences in diversity between macrophyte and control treatments. Higher fish diversity in structured habitats compared to more homogenous habitats is likely associated with increased ecomorphological diversity to exploit heterogeneous microhabitats and resources provided by the macrophytes.
Date: August 2015
Creator: Treviño, Jessica Marie
Partner: UNT Libraries

Response of fish to different simulated rates of water temperature increase

Description: We initiated this study to define the limits of effluent-temperature rate increases during reactor restart, which will help minimize fish kills. We constructed an apparatus for exposing fish to various temperature-increase regimens and conducted two experiments based on information from system tests and scoping runs. In the rate experiment, we acclimated the fish to 20{degree}C, and then raised the temperature to 40{degree}C at varying rates. Because scoping runs and literature suggested that acclimation temperature may affect temperature-related mortality, we conducted an acclimation experiment. We acclimated the fish to various temperatures, then raised the temperatures to 39--40{degree}C at a rate of 2{degree}C every 12 hours. Based on the analysis of the data, we recommend temperature-increase rates during reactor restart of 2.5{degree}C every nine hours if ambient water temperatures are over 20{degree}C. If water temperatures are at or below 20{degree}C, we recommend temperature-increase rates of 2.5{degree}C every 12 hours. No regulation of temperature is required after effluent temperatures reach 40{degree}C. We recommend further studies, including expanded testing with the simulation system and behavioral and bioenergetic investigations that may further refine acceptable rates of effluent-temperature increases.
Date: August 1, 1992
Creator: Wike, L. D. & Tuckfield, R. C.
Partner: UNT Libraries Government Documents Department

Response of fish to different simulated rates of water temperature increase

Description: We initiated this study to define the limits of effluent-temperature rate increases during reactor restart, which will help minimize fish kills. We constructed an apparatus for exposing fish to various temperature-increase regimens and conducted two experiments based on information from system tests and scoping runs. In the rate experiment, we acclimated the fish to 20{degree}C, and then raised the temperature to 40{degree}C at varying rates. Because scoping runs and literature suggested that acclimation temperature may affect temperature-related mortality, we conducted an acclimation experiment. We acclimated the fish to various temperatures, then raised the temperatures to 39--40{degree}C at a rate of 2{degree}C every 12 hours. Based on the analysis of the data, we recommend temperature-increase rates during reactor restart of 2.5{degree}C every nine hours if ambient water temperatures are over 20{degree}C. If water temperatures are at or below 20{degree}C, we recommend temperature-increase rates of 2.5{degree}C every 12 hours. No regulation of temperature is required after effluent temperatures reach 40{degree}C. We recommend further studies, including expanded testing with the simulation system and behavioral and bioenergetic investigations that may further refine acceptable rates of effluent-temperature increases.
Date: August 1, 1992
Creator: Wike, L.D. & Tuckfield, R.C.
Partner: UNT Libraries Government Documents Department

Mitigating strategies for CO/sub 2/ problems

Description: Vast uncertainties surround the ability to predict the social effects of increased carbon dioxide concentrations in the atmosphere during the next century; fossil fuel combustion rates will change, predicting global climate changes is difficult, and predicting the resulting social reactions to these change is essentially impossible. Unfortunately, the effects of carbon dioxide are likely to be insidious and difficult to connect to climate change. Myriad effects, both good and bad are unlikely to be recognized as caused by carbon dioxide. Conscious adaptation policies have the government or other social institutions act directly to mandate change in behavior through laws, fines, or subsidies. Unfortunately, such actions cannot be tailored to achieve precise objectives; they are blunt tools that should be used only for important goals and then sparingly. Unconscious adaptation takes place through behavioral changes induced by the market place or social institutions. These mechanisms can be swift and powerful, but are difficult to manipulate. Actions such as monitoring climate change and taking care to inform important groups of the current state of knowledge on carbon dioxide induced climate changes can help to speed adaptation along with contingency planning and development of nonfossil fuel technologies can speed adaptation. More important are plans which would set unconscious adaptation into motion, such as plans to disseminate information on the problem and behavior which will help individuals or firms. Of greatest importance is having a society that can quickly perceive and adapt to the new regime. This means a strong economy, high scientific and engineering capabilities, a well educated population, and a more flexible, resilient capital stock. Carbon dioxide can serve as a catalyst in promoting policies that are justified for a host of reasons.
Date: August 1, 1980
Creator: Lave, L B
Partner: UNT Libraries Government Documents Department