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Selected AbstractsTranslocation of soils to stimulate climate change: CO2 emissions and modifications to soil organic matterEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007M. Rey Summary The effect of climate change on CO2 emissions was studied on undisturbed soil monoliths (40-cm diameter, 25-cm high), which were translocated to warmer zones than their place of origin. Thirty-two months after the translocation, a climatic factor deduced from the moisture content of the soil and from the effective mean temperature (temperatures in excess of 5°C) revealed that translocation increased the potential of the climate to enhance the biological processes by between 73% and 26% compared with what the soil would support in its place of origin. At the end of the study, the transported soils had lost a large proportion of both total carbon and nitrogen (between 20 and 45%). During the experiment, the CO2 emissions from the soils, measured under field conditions, were quite variable, but were usually greater than from soils in situ. The variation in labile C in the soil throughout the experiment was calculated from a first-order kinetic equation for organic matter decay. The relative CO2 emissions, expressed in terms of the labile carbon fraction in the soils, were clearly greater in those translocated soils that underwent the most intensive climate change, which indicates that the variations in emissions over time are basically a function of the size of the labile organic matter pool. [source] Is nest-site availability limiting Lesser Kestrel populations?IBIS, Issue 4 2005A multiple scale approach The Lesser Kestrel, a colonial migratory falcon, is one of the most endangered birds in Europe and, due to a sharp population decline across much of the breeding range, is globally threatened. The reasons for this decline are unclear, but reduced nest-site availability might be a major cause. To test this hypothesis we looked at nest-site availability within Portuguese colonies in rural and urban buildings. Nest holes were larger, longer, higher and older than unoccupied cavities. A typical nest cavity was approximately 29,30 cm long, 300,340 cm high and had an inner chamber 16.5,18 cm wide. Large-scale surveys of existing buildings in Portuguese villages suggested that 85% of sites lacked suitable nest cavities. The model for selection of buildings indicated that Lesser Kestrels prefer buildings with many roof and wall cavities, and that are surrounded by extensive cereal and fallow fields. The villages selected had many old buildings and monuments, were located in areas with few rivers, and a low percentage cover of cereal, olive groves and forest. The conservation implications of these results are discussed. [source] A mesoscopic model for the behaviour of concrete under high confinementINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2009F. Dupray Abstract When impact loaded, concrete is submitted to high triaxial stresses. The experimental response of concrete under quasi-static triaxial compression is studied using a triaxial press capable of applying a mean pressure greater than 1,GPa on cylindrical samples measuring 7,cm in diameter and 14,cm high. A numerical analysis of these previous experiments is performed herein at a mesoscopic scale. Concrete is modelled as a biphasic material consisting of a mortar (cement paste and fine aggregates) and roughly spherical aggregates (with a diameter exceeding 2,mm) whose characteristics are applied on a regular cubic finite element mesh. A damage-plasticity model is then used to model the behaviour of mortar. An identification of model parameters on mortar samples and the subsequent comparison between numerical and experimental tests will be presented for hydrostatic and triaxial compression. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effects of decreasing soil water content on seminal lateral roots of young maize plantsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2006Abstract Soil micropores that contain water at or below field capacity cannot be invaded by seminal or first-order lateral roots of maize plants because their root diameters are larger than 10 ,m. Hence, at soil-water levels below field capacity plant roots must establish a new pore system by displacement of soil particles in order to access soil water. We investigated how decreasing soil water content (SWC) influences growth and morphology of the root system of young maize plants. Plants were grown in rhizotrons 40,cm wide, 50,cm high, and approximately 0.7,cm thick. Five SWC treatments were established by addition of increasing amounts of water to soil and thorough mixing before filling the rhizotrons. No water was added to treatments 1,4 throughout the experiment. Treatment 5 was watered frequently throughout the experiment to serve as a control. Seminal-root length and SWC in soil layers 0,10, 10,20, 20,30, 30,40, and 40,50,cm were measured at intervals of 2,3 d on scanner images by image analysis. At 15 d after planting, for treatments 1,4 shoot dry weight and total root length were directly related to the amount of water added to the soil, and for treatments 4 and 5, total root length and shoot dry weights were similar. Length of seminal roots visible at the transparent surface of the rhizotron for all treatments was highest in the uppermost soil layer and decreased with distance from the soil surface. For all layers, seminal-root elongation rate was at maximum above a SWC of 0.17,cm3,cm,3, corresponding to a matric potential of ,30 kPa. With decreasing SWC, elongation rate decreased, and 20% of maximum seminal root elongation rate was observed below SWC of 0.05,cm3,cm,3. After destructive harvest for treatment 1,4, number of (root-) tips per unit length of seminal root was found uninfluenced over the range of initial SWC from 0.10 to 0.26,cm3,cm,3. However, initial SWC close to the permanent wilting point strongly increased number of tips. Average root length of first-order lateral (FOL) roots increased as initial SWC increased, and the highest length was found for the frequently watered treatment 5. The results of the study suggest that the ability to produce new FOL roots across a wide range of SWC may give maize an adaptive advantage, because FOL root growth can rapidly adapt to changing soil moisture conditions. [source] Role of Length Scale on Pressure Increase and Yield of Poly(vinyl butyral),Barium Titanate,Platinum Multilayer Ceramic Capacitors during Binder BurnoutJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000Leo C.-K. The binder-burnout kinetics of poly(vinyl) butyral from BaTiO3 multilayer ceramic capacitors with platinum metal electrodes were analyzed by combining thermogravimetric analysis with infrared spectroscopy. The rate of weight loss was accelerated when both BaTiO3 and platinum metal were present, and the presence of both metal and ceramic enhanced the production of CO2. The activation energy and pre-exponential factor were determined by analysis of the weight-loss data with a first-order kinetics model. Then, the decomposition kinetics were incorporated into a coupled heat- and mass-transport model to predict pressure increases as a function of the heating cycle. The heating cycles determined in this manner then were used to evaluate the yield of capacitors 1.3,3.8 cm long and 0.3,1.3 cm high. The optimum yield was realized at an aspect ratio (height:length) of 1:3. [source] Mounding as a Technique for Restoration of Prairie on a Capped Landfill in the Puget Sound LowlandsRESTORATION ECOLOGY, Issue 2 2002Kern Ewing Abstract Closed landfills create large open spaces that are often proposed as sites for restored or created ecosystems. Grasslands are probably prescribed most often because of the presumption that grass root systems will not breach the landfill cap. Capped landfills have a number of soil degradation problems, including compaction, decreased permeability, lack of organic material, diminished soil fauna, inappropriate texture, and lack of structure. In this study in the Puget Sound lowlands, Washington, U.S.A., mounding (low sandy-loam mounds, about 20 cm high and 2 m in diameter), addition of fertilizer, and mulching with yard-waste compost were applied to landfill sites as treatments in a factorial-design experiment. Prairie plants (1,344 individuals, 7 species) were planted into 4-m2 plots (n = 48), and plant growth and survival and the increase in weed biomass were monitored for 3 years. Mulching had no effect on plant survival or growth. Fertilization had a negative effect on Lupinus lepidus, a nitrogen-fixing species. Mounding had a positive effect on growth and survival of Eriophyllum lanatum, Festuca idahoensis, and Aster curtus. Potentilla pacifica was indifferent to mounding, and Carex inops responded negatively. Mounds should probably be used as one element of a complex of habitats on restored landfills. [source] Electronic subretinal implants allow blind retinitis pigmentosa patients to read letters and recognize the direction of fine stripe patternsACTA OPHTHALMOLOGICA, Issue 2009E ZRENNER Purpose Restoration of letter reading and stripe pattern recognition in blind RP patients by placing subretinal implants transchoroidally near the macula, consisting of two arrays: 4x4 electrodes controlled retroauricularly via a subdermal line for direct stimulation ("DS array") and a "chip" (3x3x0,1 mm),1500 electrodes. Methods Letters and stripe pattern were presented to 3 patients via the light sensitive chip , by patterns steadily presented at a screen. On the DS array the sensation evoked by each individual pulse consists of whitish round dot, clearly separated from its neighbor. Patterns consisting of such 4 x 4 dots correspond to letters of approximately 5 cm diameter presented at 60 cm distance. Results Pat.1 correctly (20/24) recognized the direction of the letter "U", presented with the opening in four different directions (DS array). Pat.2 correctly (12/12) differentiated letters via DS array (e.g. COIL). With the light sensitive chip, he correctly (22/24) differentiated letters (e.g. LITZ; 8,5 cm high, 1.7 cm line width) steadily presented on a screen at 62 cm distance Pat.3 recognized (15/20 correct, 4AFC) the direction of lines or stripe patterns with the chip, as did Pat.1 (11/14, 2AFC) and Pat.2 (11/12 4AFC) up to 0.35 cycles/deg. Conclusion Active subretinal multielectrode implants with currents close to produce retinotopically correct patterns that allow for the first time recognition of individual letters and stripe patterns up to 0.35 cycles/deg clearly supporting the feasibility of light sensitive subretinal multi-electrode devices for restoration of useful vision. [source] | |||||||||||||