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LINCOLN, NE, United States

Liu Z.,China Agricultural University | Liu Z.,University of Nebraska - Lincoln | Yang X.,China Agricultural University | Hubbard K.G.,University of Nebraska - Lincoln | And 2 more authors.
Global Change Biology | Year: 2012

Northeast China (NEC) is not only one of the major agricultural production areas in China, but it is also the most susceptible to climate variability. This led us to investigate the impact of climate change on maize potential yield and yield gaps in this region, where maize accounts for about 30% of the nation's production. The APSIM-Maize model was calibrated and validated for maize phenology and yields. The validated model was then used to estimate potential yields, rain-fed potential yields, and yield gaps for assessing the climate impacts on maize productivity in NEC. During maize growing seasons from 1981 to 2010, the analysis indicates a warming trend all across NEC, whereas the trends in solar radiation and total precipitation tended to decrease. When the same hybrid was specified in APSIM for all years, a simulated increase of maximum temperature resulted in a negative impact on both potential yield and rain-fed potential yield. A simulated increase in minimum temperature produced no significant changes in potential or rain-fed potential yield. However, the increase of minimum temperature was shown to result in a positive impact on the on-farm yield, consistent with our finding that farmers adopted longer season hybrids for which the increase in minimum temperature provided better conditions for germination, emergence, and grain filling during night time. The gap between potential and rain-fed potential yields was shown to be larger at locations with lower seasonal precipitation (<500 mm). Our results indicate that regions with the largest yield gaps between rain-fed potential and on-farm yields were located in the southeast of NEC. Within NEC, on-farm maize yields were, on average, only 51% of the potential yields, indicating a large exploitable yield gap, which provides an opportunity to significantly increase production by effective irrigation, fertilization, herbicide, and planting density in NEC. © 2012 Blackwell Publishing Ltd. Source

Fratini G.,Li-Cor Biosciences, Inc. | Mauder M.,Karlsruhe Institute of Technology
Atmospheric Measurement Techniques | Year: 2014

A comparison of two popular eddy-covariance software packages is presented, namely, EddyPro and TK3. Two approximately 1-month long test data sets were processed, representing typical instrumental setups (i.e., CSAT3/LI-7500 above grassland and Solent R3/LI-6262 above a forest). The resulting fluxes and quality flags were compared. Achieving a satisfying agreement and understanding residual discrepancies required several iterations and interventions of different nature, spanning from simple software reconfiguration to actual code manipulations. In this paper, we document our comparison exercise and show that the two software packages can provide utterly satisfying agreement when properly configured. Our main aim, however, is to stress the complexity of performing a rigorous comparison of eddy-covariance software. We show that discriminating actual discrepancies in the results from inconsistencies in the software configuration requires deep knowledge of both software packages and of the eddy-covariance method. In some instances, it may be even beyond the possibility of the investigator who does not have access to and full knowledge of the source code. Being the developers of EddyPro and TK3, we could discuss the comparison at all levels of details and this proved necessary to achieve a full understanding. As a result, we suggest that researchers are more likely to get comparable results when using EddyPro (v5.1.1) and TK3 (v3.11)-at least with the setting presented in this paper-than they are when using any other pair of EC software which did not undergo a similar cross-validation. As a further consequence, we also suggest that, to the aim of assuring consistency and comparability of centralized flux databases, and for a confident use of eddy fluxes in synthesis studies on the regional, continental and global scale, researchers only rely on software that have been extensively validated in documented intercomparisons. © 2014 Author(s). Source

Detto M.,University of California at Berkeley | Verfaillie J.,University of California at Berkeley | Anderson F.,U.S. Geological Survey | Xu L.,Li-Cor Biosciences, Inc. | Baldocchi D.,University of California at Berkeley
Agricultural and Forest Meteorology | Year: 2011

Closed- and open-path methane gas analyzers are used in eddy covariance systems to compare three potential methane emitting ecosystems in the Sacramento-San Joaquin Delta (CA, USA): a rice field, a peatland pasture and a restored wetland. The study points out similarities and differences of the systems in field experiments and data processing. The closed-path system, despite a less intrusive placement with the sonic anemometer, required more care and power. In contrast, the open-path system appears more versatile for a remote and unattended experimental site. Overall, the two systems have comparable minimum detectable limits, but synchronization between wind speed and methane data, air density corrections and spectral losses have different impacts on the computed flux covariances. For the closed-path analyzer, air density effects are less important, but the synchronization and spectral losses may represent a problem when fluxes are small or when an undersized pump is used. For the open-path analyzer air density corrections are greater, due to spectroscopy effects and the classic Webb-Pearman-Leuning correction. Comparison between the 30-min fluxes reveals good agreement in terms of magnitudes between open-path and closed-path flux systems. However, the scatter is large, as consequence of the intensive data processing which both systems require. © 2011. Source

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 212.86K | Year: 2014

DESCRIPTION (provided by applicant): Reactive oxygen species (ROS) are involved in numerous cell-signaling pathways. They have been implicated in over 150 diseases including cancer, arthritis, Parkinson's disease, diabetes, myocardial infarction and atherosclerosis. The need to understand the role of ROS in these processes is evidenced by the 80,000 publications in this field during the last five years alone. Recently, in a paper James D. Watson called among my most important work since the double helix, ,he posited a theory that links cancer progression in late stages of the disease to the presence of antioxidants and the role of ROS (Watson, J. Open Biol. 2013, 3, 120144). Despite the immense interest and importance of ROS research, there are no probes that combine reliability, sensitivity, and efficiency for detecting ROS in cell culture, ex vivo, and in vivo. No current commercially available probe can image ROS in vivo, which presents a significant impediment in understanding the role of ROS in th

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1000.00K | Year: 2014

The increasing concentration of carbon dioxide in the atmosphere is changing the earths climate. Climate change will cause periods of extremely high daily temperatures, increase the frequency of heavy rainfall, intensify droughts, increase the maximum wind speed of cyclones, and cause sea levels to rise. The unavailability of low-cost, high-performance atmospheric carbon dioxide analyzers constrains the efforts of environmental scientists to monitor carbon dioxide at local, regional, and global scales with the coverage needed to advance our understanding of climate change processes.

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