Liu Z.,China Agricultural University |
Liu Z.,University of Nebraska - Lincoln |
Hubbard K.G.,University of Nebraska - Lincoln |
Lin X.,Kansas State University |
And 2 more authors.
Global Change Biology | Year: 2013
Northeast China (NEC) accounts for about 30% of the nation's maize production in China. In the past three decades, maize yields in NEC have increased under changes in climate, cultivar selection and crop management. It is important to investigate the contribution of these changing factors to the historical yield increases to improve our understanding of how we can ensure increased yields in the future. In this study, we use phenology observations at six sites from 1981 to 2007 to detect trends in sowing dates and length of maize growing period, and then combine these observations with in situ temperature data to determine the trends of thermal time in the maize growing period, as a measure of changes in maize cultivars. The area in the vicinity of these six sites accounts for 30% of NEC's total maize production. The agricultural production systems simulator, APSIM-Maize model, was used to separate the impacts of changes in climate, sowing dates and thermal time requirements on maize phenology and yields. In NEC, sowing dates trended earlier in four of six sites and maturity dates trended later by 4-21 days. Therefore, the period from sowing to maturity ranged from 2 to 38 days longer in 2007 than it was in 1981. Our results indicate that climate trends alone would have led to a negative impact on maize. However, results from the adaptation assessments indicate that earlier sowing dates increased yields by up to 4%, and adoption of longer season cultivars caused a substantial increase in yield ranging from 13% to 38% over the past 27 years. Therefore, earlier sowing dates and introduction of cultivars with higher thermal time requirements in NEC have overcome the negative effects of climate change and turned what would have otherwise been a loss into a significant increase in maize yield. © 2013 John Wiley & Sons Ltd.
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.
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).
Kachanov A.,Li-Cor Biosciences, Inc. |
Koulikov S.,Li-Cor Biosciences, Inc. |
Tittel F.K.,Rice University
Applied Physics B: Lasers and Optics | Year: 2013
An ultra-sensitive photo-acoustic spectrometer using a 10.4 μm broadly tunable mid-IR external cavity quantum cascade laser (EC-QCL) coupled with optical feedback to an optical power buildup cavity with high reflectivity mirrors was developed and tested. A laser optical power buildup factor of 181 was achieved, which corresponds to an intra-cavity power of 9.6 W at a wavelength of 10.4 μm. With a photo-acoustic resonance cell placed inside the cavity this resulted in the noise-equivalent absorption coefficient of 1.9 × 10-10 cm-1 Hz-1/2, and a normalized noise-equivalent absorption of 1.1 × 10-11 cm-1 W Hz-1/2. A novel photo-acoustic signal normalization technique makes the photo-acoustic spectrometer's response immune to changes and drifts in the EC-QCL excitation power, EC-QCL to cavity coupling efficiency and cavity mirrors aging and contamination. An automatic lock of the EC-QCL to the cavity and optical feedback phase optimization permitted long wavelength scans within the entire EC-QCL spectral tuning range. © 2012 Springer-Verlag Berlin Heidelberg.
Draney D.R.,Li-Cor Biosciences, Inc.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015
A monofunctional, heptamethine dye, IRDye® 800CW, is being manufactured under GMP conditions for use in human clinical trials. When attached to a suitable targeting agent and paired with an appropriate camera system, the dye allows Near Infrared (NIR) fluorescence imaging of tumor tissue during surgery. The talk will describe the properties of the dye and give an overview of current and planned clinical trials in Europe and the USA. The dye is available in both the NHS ester and carboxylate forms for conjugation to targeting molecules. A GMP toxicology study of the dye was described in a previous publication. © 2015 SPIE.
Gong H.,Li-Cor Biosciences, Inc. |
Kovar J.,Li-Cor Biosciences, Inc. |
Little G.,Li-Cor Biosciences, Inc. |
Chen H.,Li-Cor Biosciences, Inc. |
Olive D.M.,Li-Cor Biosciences, Inc.
Neoplasia | Year: 2010
Overexpression of epidermal growth factor receptor (EGFR) is associated with many types of cancers. It is of great interest to noninvasively image the EGFR expression in vivo. In this study, we labeled an EGFR-specific Affibody molecule (Eaff) with a near-infrared (NIR) dye IRDye800CW maleimide and tested the binding of this labeled molecule (Eaff800) in cell culture and xenograft mouse tumor models. Unlike EGF, Eaff did not activate the EGFR signaling pathway. Results showed that Eaff800 was bound and taken up specifically by EGFR-overexpressing A431 cells. When Eaff800 was intravenously injected into nude mice bearing A431 xenograft tumors, the tumor could be identified 1 hour after injection and it became most prominent after 1 day. Images of dissected tissue sections demonstrated that the accumulation of Eaff800 was highest in the liver, followed by the tumor and kidney. Moreover, in combination with a human EGFR type 2 (HER2)-specific probe Haff682, Eaff800 could be used to distinguish between EGFR- and HER2-overexpressing tumors. Interestingly, the organ distribution pattern and the clearance rate of Eaff800 were different from those of Haff682. In conclusion, Eaff molecule labeled with a NIR fluorophore is a promising molecular imaging agent for EGFR-overexpressing tumors. Copyright © 2010 Neoplasia Press, Inc. All rights reserved.
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2013
LI-COR Biosciences proposes to develop a new sensor that measures the concentration of carbon dioxide in the atmosphere with precision of 1 part in 3000 within one minute, requires only small amounts of gas, operates unattended in the field for at least 6 months, costs less than $5000, and is insensitive to motion. The sensor will advance a technology known as optical feedback cavity enhanced absorption spectroscopy (OF-CEAS). OF-CEAS can measure absorption more accurately than any other cavity enhanced absorption spectroscopy technique because the cavity delivers a much more intense signal beam to the photodetector and thereby enables an unparalleled signal-to-noise ratio (~10,000). OF-CEAS makes it possible to calculate the optical frequency of each measurement point with high accuracy by scanning the laser over a fixed grid of equidistant cavity modes. OF-CEAS makes it possible to reduce manufacturing costs in many ways: control the optical feedback by optimizing mirror reflectivities rather than incorporating a Faraday isolator, calculate the optical frequency of each cavity mode by taking advantage of the fixed grid of cavity modes rather than measuring optical frequency with an expensive wavelength monitor, incorporate small, relatively inexpensive mirrors into a small (~1 mL) cavity that requires only small quantities of calibration gases, employ relatively low-cost non-fiber-coupled lasers, and assemble instruments by mass production techniques. Increasing concentrations of carbon dioxide in the atmosphere are changing the earths climate. Climate change will cause 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 CO2 sensors constrains the effort of environmental scientists to monitor CO2 at local, regional, and global scales. LI-COR Biosciences is introducing a new sensor technology that can measure carbon dioxide with state-of-the-art precision while reducing the price by a factor of 10. Commercial Applications: Scientists in university and government laboratory will apply the proposed sensors to measure carbon dioxide in the atmosphere. The sensors will help DOE to achieve its mission, which is to ensure Americas security and prosperity by addressing its energy, environmental, and nuclear challenges through transformative science and technology solutions. The proposed sensors will benefit the public by helping to provide a scientific basis for policies that mitigate the impacts of climate change.
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.
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
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.