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Drought- and heat-driven tree mortality, along with associated insect outbreaks, have been observed globally in recent decades and are expected to increase in future climates. Despite its potential to profoundly alter ecosystem carbon and water cycles, how tree mortality scales up to ecosystem functions and fluxes is uncertain. We describe a framework for this scaling where the effects of mortality are a function of the mortality attributes, such as spatial clustering and functional role of the trees killed, and ecosystem properties, such as productivity and diversity. We draw upon remote-sensing data and ecosystem flux data to illustrate this framework and place climate-driven tree mortality in the context of other major disturbances. We find that emerging evidence suggests that climate-driven tree mortality impacts may be relatively small and recovery times are remarkably fast (~4 years for net ecosystem production). We review the key processes in ecosystem models necessary to simulate the effects of mortality on ecosystem fluxes and highlight key research gaps in modeling. Overall, our results highlight the key axes of variation needed for better monitoring and modeling of the impacts of tree mortality and provide a foundation for including climate-driven tree mortality in a disturbance framework.

Accurately predicting the response of Amazonia to climate change is important for predicting climate change across the globe. Changes in multiple climatic factors simultaneously result in complex non-linear ecosystem responses, which are difficult to predict using vegetation models. Using leaf- and canopy-scale observations, this study evaluated the capability of five vegetation models (Community Land Model version 3.5 coupled to the Dynamic Global Vegetation model – CLM3.5–DGVM; Ecosystem Demography model version 2 – ED2; the Joint UK Land Environment Simulator version 2.1 – JULES; Simple Biosphere model version 3 – SiB3; and the soil–plant–atmosphere model – SPA) to simulate the responses of leaf- and canopy-scale productivity to changes in temperature and drought in an Amazonian forest. The models did not agree as to whether gross primary productivity (GPP) was more sensitive to changes in temperature or precipitation, but all the models were consistent with the prediction that GPP would be higher if tropical forests were 5 °C cooler than current ambient temperatures. There was greater model–data consistency in the response of net ecosystem exchange (NEE) to changes in temperature than in the response to temperature by net photosynthesis (An), stomatal conductance (gs) and leaf area index (LAI). Modelled canopy-scale fluxes are calculated by scaling leaf-scale fluxes using LAI. At the leaf-scale, the models did not agree on the temperature or magnitude of the optimum points of An, Vcmax or gs, and model variation in these parameters was compensated for by variations in the absolute magnitude of simulated LAI and how it altered with temperature. Across the models, there was, however, consistency in two leaf-scale responses: (1) change in An with temperature was more closely linked to stomatal behaviour than biochemical processes; and (2) intrinsic water use efficiency (IWUE) increased with temperature, especially when combined with drought. These results suggest t

© 2015 Macmillan Publishers Limited. All rights reserved. Stomatal conductance (g s) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of g s in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of g s that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed g s obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model and the leaf and wood economics spectrum. We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of g s across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.

Importance: Due to increasing demand for sleep services, there has been growing interest in ambulatory models of care for patients with obstructive sleep apnea. With appropriate training and simplified management tools, primary care physicians are ideally positioned to take on a greater role in diagnosis and treatment. Objective: To compare the clinical efficacy and within-trial costs of a simplified model of diagnosis and care in primary care relative to that in specialist sleep centers. Design, Setting, and Patients: A randomized, controlled, noninferiority study involving 155 patients with obstructive sleep apnea that was treated at primary care practices (n=81) in metropolitan Adelaide, 3 rural regions of South Australia or at a university hospital sleep medicine center in Adelaide, Australia (n=74), between September 2008 and June 2010. Interventions: Primary care management of obstructive sleep apnea vs usual care in a specialist sleep center; both plans included continuous positive airway pressure, mandibular advancement splints, or conservative measures only. Main Outcome and Measures: The primary outcome was 6-month change in Epworth Sleepiness Scale (ESS) score, which ranges from 0 (no daytime sleepiness) to 24 points (high level of daytime sleepiness). The noninferiority margin was -2.0. Secondary outcomes included disease-specific and general quality of life measures, obstructive sleep apnea symptoms, adherence to using continuous positive airway pressure, patient satisfaction, and health care costs. Results: There were significant improvements in ESS scores from baseline to 6 months in both groups. In the primary care group, the mean baseline score of 12.8 decreased to 7.0 at 6 months (P < .001), and in the specialist group, the score decreased from a mean of 12.5 to 7.0 (P < .001). Primary care management was noninferior to specialist management with a mean change in ESS score of 5.8 vs 5.4 (adjusted difference, -0.13; lower bound of 1-sided 95% CI, -1

Coarse woody debris (CWD, dead wood sections ≥10 cm diameter) represents a large store of carbon in tropical forests; however, estimates of the flux of carbon from CWD in these forests remain poorly constrained. The objective of this study was to resolv

Copper nickel separation is performed by mineral processing techniques both pre and post smelting in Copper Cliff at Vale Canada's operations (Sudbury, Ontario). The separation at Clarabelle Mill takes advantage of the ore mineralogy to affect a separation on the rougher concentrate where chalcopyrite and pentlandite exhibit high liberation and high recoveries thus their separation is simple although incomplete. The copper concentrate comprises only 50% of the copper in ore with the remaining copper being separated post smelting in the matte separation plant where the slow cooled Bessemer matte is again treated by mineral processing operations using flotation to separate the chalcocite and heazlewoodite and magnetic separators to remove a metallic nickel alloy. Discussion is presented of the mineralogy, separation processes and work currently underway to improve the separation of copper from nickel in these plants. (Authors.), Copper nickel separation is performed by mineral processing techniques both pre and post smelting in Copper Cliff at Vale Canada's operations (Sudbury, Ontario). The separation at Clarabelle Mill takes advantage of the ore mineralogy to affect a separation on the rougher concentrate where chalcopyrite and pentlandite exhibit high liberation and high recoveries thus their separation is simple although incomplete. The copper concentrate comprises only 50% of the copper in ore with the remaining copper being separated post smelting in the matte separation plant where the slow cooled Bessemer matte is again treated by mineral processing operations using flotation to separate the chalcocite and heazlewoodite and magnetic separators to remove a metallic nickel alloy. Discussion is presented of the mineralogy, separation processes and work currently underway to improve the separation of copper from nickel in these plants. (Authors.)

The deportment of chalcocite (Cu2S) and heazlewoodite (Ni3S2) in Vale's Bessemer matte flotation circuit in Sudbury, Ontario, was investigated both in the plant and in laboratory flotation experiments. Insufficient selectivity was reported due to Cu2S not being entirely recovered in the rougher/scavengers and Ni3S2, depressed in the process, contaminating the flotation concentrate. It was found that Cu2S misreporting to the flotation tailings is mainly ultrafine, smaller than 6 micrometers, suggesting that surface oxidation and the low collision efficiency of fine particles in flotation are the possible causes of Cu2S losses. By contrast, Ni3S2 misreporting to the flotation concentrate is mainly in the intermediate size fractions from 6 to 38 micrometers and less than 40% of the heazlewoodite is in composites with chalcocite, the majority being liberated. Particle surface analysis by means of time-of-flight secondary ion mass spectrometry revealed that Ni3S2 in the concentrate is Cu-activated, and that the diphenyl guanidine collector adsorbs on the exposed Cu on the mineral surface. The role of pulp electrochemistry was also investigated, showing that the pulp potential in primary grinding is critical for selectivity. Strategies to reduce Cu activation of Ni3S2 in the process are suggested, as well as modifications to the current circuit flowsheet for improved plant performance., The deportment of chalcocite (Cu2S) and heazlewoodite (Ni3S2) in Vale's Bessemer matte flotation circuit in Sudbury, Ontario, was investigated both in the plant and in laboratory flotation experiments. Insufficient selectivity was reported due to Cu2S not being entirely recovered in the rougher/scavengers and Ni3S2, depressed in the process, contaminating the flotation concentrate. It was found that Cu2S misreporting to the flotation tailings is mainly ultrafine, smaller than 6 micrometers, suggesting that surface oxidation and the low collision efficiency of fine particles in flotation are the possible causes of Cu2S losses. By contrast, Ni3S2 misreporting to the flotation concentrate is mainly in the intermediate size fractions from 6 to 38 micrometers and less than 40% of the heazlewoodite is in composites with chalcocite, the majority being liberated. Particle surface analysis by means of time-of-flight secondary ion mass spectrometry revealed that Ni3S2 in the concentrate is Cu-activated, and that the diphenyl guanidine collector adsorbs on the exposed Cu on the mineral surface. The role of pulp electrochemistry was also investigated, showing that the pulp potential in primary grinding is critical for selectivity. Strategies to reduce Cu activation of Ni3S2 in the process are suggested, as well as modifications to the current circuit flowsheet for improved plant performance.

The plant in Sudbury, Ontario, has since 1948 successfully used froth flotation and magnetic separation of Bessemer matte into Cu and Ni sulphides and Ni-Cu metallic alloy for downstream processing; equipment upgrades have been performed periodically, but the flowsheet has generally remained unchanged since the early 1970s after the 1960s addition of middlings and scavenger circuits. A drive to improve metallurgical performance resulted in a trial of a scalping flotation column to produce a final Cu concentrate ahead of the cleaner circuit feed in order to take advantage of a high degree of Cu mineral liberation, reduce cleaner-recleaner circulating loads and decrease the resulting loss of selectivity. The plant study indicated that 50% of Cu contained in the rougher concentrate could be recovered at final grade target. In addition a 1.5% increase in Cu recovery to copper concentrate was achievable during the scalper trial, considered to be due to a reduction in the generation of fine chalcocite. To optimise plant performance, deficiencies identified are being addressed prior to the instigation of a long-term trial to confirm the benefits of Cu scalping., The plant in Sudbury, Ontario, has since 1948 successfully used froth flotation and magnetic separation of Bessemer matte into Cu and Ni sulphides and Ni-Cu metallic alloy for downstream processing; equipment upgrades have been performed periodically, but the flowsheet has generally remained unchanged since the early 1970s after the 1960s addition of middlings and scavenger circuits. A drive to improve metallurgical performance resulted in a trial of a scalping flotation column to produce a final Cu concentrate ahead of the cleaner circuit feed in order to take advantage of a high degree of Cu mineral liberation, reduce cleaner-recleaner circulating loads and decrease the resulting loss of selectivity. The plant study indicated that 50% of Cu contained in the rougher concentrate could be recovered at final grade target. In addition a 1.5% increase in Cu recovery to copper concentrate was achievable during the scalper trial, considered to be due to a reduction in the generation of fine chalcocite. To optimise plant performance, deficiencies identified are being addressed prior to the instigation of a long-term trial to confirm the benefits of Cu scalping.

We have fabricated SiC MESFETs with more than 60 watts of output power at 450 MHz from single 21.6mm gate periphery devices (2.9 W/mm) and 27 wafts of output power at 3 GHz from single 14.4mm SiC MESFET devices (1.9 W/mm). We have also demonstrated more than 6.7 W/mm CW power from 400 micronmeter GaN/AlGaN HEMT devices for X band (10 GHz) applications. These excellent device performances have been attributed to the improved substrate and epitaxial films quality, optimized device thermal management, and enhanced device fabrication technologies. The substrates and epitaxial films from different sources were compared and some showed significant less SiC substrate micropipes confirmed by X-ray topography and epitaxial defects characterized by optical defect mapping., This article is from ADA423729 Proceedings IEEE Lester Eastman Conference on High Performance Devices at University of Delaware, Newark, Delaware, August 6, 7, and 8. 2002