Relevant prior knowledge moderates the effect of elaboration during small group discussion on academic achievement

This study set out to test whether relevant prior knowledge would moderate a positive effect on academic achievement of elaboration during small-group discussion. In a 2 × 2 experimental design, 66 undergraduate students observed a video showing a small-group problem-based discussion about thunder and lightning. In the video, a teacher asked questions to the observing participants. Participants either elaborated by responding to these questions, or did not elaborate, but completed a

Simulating the carbon balance of a temperate larch forest under various meteorological conditions

<p>Abstract</p> <p>Background</p> <p>Changes in the timing of phenological events may cause the annual carbon budget of deciduous forests to change. Therefore, one should take such events into account when evaluating the effects of global warming on deciduous forests. In this article, we report on the results of numerical experiments done with a model that includes a phenological module simulating the timing of bud burst and other phenological events and estimating maximum leaf area index.</p> <p>Results</p> <p>This study suggests that the negative effects of warming on tree productivity (net primary production) outweigh the positive effects of a prolonged growing season. An increase in air temperature by 3°C (5°C) reduces cumulative net primary production by 21.3% (34.2%). Similarly, cumulative net ecosystem production (the difference between cumulative net primary production and heterotrophic respiration) decreases by 43.5% (64.5%) when temperatures are increased by 3°C (5°C). However, the positive effects of CO₂enrichment (2 × CO₂) outweigh the negative effects of warming (<5°C).</p> <p>Conclusion</p> <p>Although the model was calibrated and validated for a specific forest ecosystem, the implications of the study may be extrapolated to deciduous forests in cool-temperate zones. These forests share common features, and it can be conjectured that carbon stocks would increase in such forests in the face of doubled CO₂and increased temperatures as long as the increase in temperature does not exceed 5°C.</p

Expanding the Paradigms of Plant Pathogen Life History and Evolution of Parasitic Fitness beyond Agricultural Boundaries

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A three-dimensional synthesis study of delta O-18 in atmospheric CO2 .1. Surface fluxes

The isotope O-18 in CO2 is of particular interest in studying the global carbon cycle because it is sensitive to the processes by which the global land biosphere absorbs and respires CO2. Carbon dioxide and water exchange isotopically both in leaves and in soils, and the O-18 character of atmospheric CO2 is strongly influenced by the land biota, which should constrain the gross primary productivity and total respiration of land ecosystems, In this study we calculate the global surface fluxes of O-18 for vegetation and soils using the SiB2 biosphere model coupled with the Colorado State University general circulation model. This approach makes it possible to use physiological variables that are consistently weighted by the carbon assimilation rate and integrated through the vegetation canopy, We also calculate the air-sea exchange of O-18 and the isotopic character of fossil emissions and biomass burning. Global mean values of the isotopic exchange with each reservoir are used to close the global budget of O-18 in CO2 results confirm the fact that the land biota exert a dominant control on the delta(18)O of the atmospheric reservoir, At the global scale, exchange with the canopy produces an isotopic enrichment of CO2, whereas exchange with soils has the opposite effect