Above and belowground community strategies respond to different global change drivers

Environmental changes alter the diversity and structure of communities. By shifting the range of species traits that will be successful under new conditions, environmental drivers can also dramatically impact ecosystem functioning and resilience. Above and belowground communities jointly regulate whole-ecosystem processes and responses to change, yet they are frequently studied separately. To determine whether these communities respond similarly to environmental changes, we measured taxonomic and trait-based responses of plant and soil microbial communities to four years of experimental warming and nitrogen deposition in a temperate grassland. Plant diversity responded strongly to N addition, whereas soil microbial communities responded primarily to warming, likely via an associated decrease in soil moisture. These above and belowground changes were associated with selection for more resource-conservative plant and microbe growth strategies, which reduced community functional diversity. Functional characteristics of plant and soil microbial communities were weakly correlated (P = 0.07) under control conditions, but not when above or belowground communities were altered by either global change driver. These results highlight the potential for global change drivers operating simultaneously to have asynchronous impacts on above and belowground components of ecosystems. Assessment of a single ecosystem component may therefore greatly underestimate the whole-system impact of global environmental changes

Towards the total synthesis of Ajudazol B

Ajudazol B is a polyketide secondary metabolite, isolated from Chondromyces crocatus in 2002, that exhibits anti-fungal activity through potent inhibition of the electron transport chain. The main objective of the work described in this thesis was to use and expand the oxidative rearrangement of isobenzofurans to generate isochromanones, and apply this towards the total synthesis of ajudazol B. The rearrangement was used as a key step in the synthesis of the full ajudazol B framework. The synthesis was achieved in 20 steps and 11% overall yield. The isomer of ajudazol B was synthesised in 21 steps and 8% overall yield. Its biological activity remains to be determined

Paradoxical popups: Why are they hard to catch?

Even professional baseball players occasionally find it difficult to gracefully approach seemingly routine pop-ups. This paper describes a set of towering pop-ups with trajectories that exhibit cusps and loops near the apex. For a normal fly ball, the horizontal velocity is continuously decreasing due to drag caused by air resistance. But for pop-ups, the Magnus force (the force due to the ball spinning in a moving airflow) is larger than the drag force. In these cases the horizontal velocity decreases in the beginning, like a normal fly ball, but after the apex, the Magnus force accelerates the horizontal motion. We refer to this class of pop-ups as paradoxical because they appear to misinform the typically robust optical control strategies used by fielders and lead to systematic vacillation in running paths, especially when a trajectory terminates near the fielder. In short, some of the dancing around when infielders pursue pop-ups can be well explained as a combination of bizarre trajectories and misguidance by the normally reliable optical control strategy, rather than apparent fielder error. Former major league infielders confirm that our model agrees with their experiences.Comment: 28 pages, 10 figures, sumitted to American Journal of Physic

Role of science in ecosystem management

Roberts argues that in order to implement ecosystem management, resource management must switch its ecological perspective from an individual-and population-based focus to ecosystem-and landscape-based ecology; from an object (form) to context (function) approach; and adopt a multi-scalar modeling approach. A major role for science in EM is to predict ecosystem behavior under alternative management strategies. Wilcox, Risbrudt, Thomas, and Kessler all emphasized the critical role of a higher level of science, although Daniels pointed out that there is a risk of creating a politics of expertise. Thus participating scientists have a strong responsibility to communicate their knowledge to the public in understandable ways

Cu₂SiSe₃ as a promising solar absorber: harnessing cation dissimilarity to avoid killer antisites

Copper-chalcogenides are promising candidates for thin film photovoltaics due to their ideal electronic structure and potential for defect tolerance. To this end, we have theoretically investigated the optoelectronic properties of Cu₂SiSe₃, due to its simple ternary composition, and the favourable difference in charge and size between the cation species, limiting antisite defects and cation disorder. We find it to have an ideal, direct bandgap of 1.52 eV and a maximum efficiency of 30% for a 1.5 μm-thick film at the radiative limit. Using hybrid density functional theory, the formation energies of all intrinsic defects are calculated, revealing the p-type copper vacancy as the dominant defect species, which forms a perturbed host state. Overall, defect concentrations are predicted to be low and have limited impact on non-radiative recombination, as a consequence of the p–d coupling and antibonding character at the valence band maxima. Therefore, we propose that Cu₂SiSe₃ should be investigated further as a potential defect-tolerant photovoltaic absorber

Research Report No. 20, Stumpage Price Trends of Pine Sawtimber and Pulpwood in East Texas, Update: 1977-1987

An update of past stumpage price performance for East Texas pine sawtimber and pulpwood is presented, using information from Texas Forest Service 1983-87 and Timber Mart-South 1977-87. In ~ltlon. information from the Louisiana Department of Agriculture on stumpage price trends in Louisiana between 1955-87 is described. Two Prognostications on future stumpage price trends are included

Research Reports No. 14, Stumpage Price Trends of Pine Sawtimber and Pulpwood in East Texas, 1977-1986

Three different records of past stumpage price performance for Pine sawtimber and pulpwood are presented: Texas Forest Service 1983-86, Timber Mart South l 977-86 and Louisiana Departrnent of Agriculture 1955-86. The first two represent standing timber prices in East Texas, and the latter represents prices over a 32 year period in an adjacent state. In addition, a prognostication on future stumpage price trends is included