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A Spatial Analysis of Irrigation Technology

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Natural Resources 2013年第4期4卷 307-318页

作者： Andrew Wright darren hudson Maria Mutuc Department of Agricultural and Applied Economics Texas Tech University Lubbock USA

The nature of spatial spillovers in the adoption of irrigation technology is examined in this paper. Adopting a new technology is a decision that is based on economic and individual-specific factors. One of these individual factors might be communication with other users. It makes sense to expect that contact between users and non-users would follow a spatial pattern, and if knowledge spillovers are important to the adoption decision then resource managers need to be aware of their existence. Using counties in the Texas High Plains as the study area, the adoption of center pivot technology is examined using both Ordinary Least Squares and spatial regression models to determine if knowledge spillovers exist. Ultimately, no evidence was found that adoption practices in a county affects its neighbors;however, geographic location does matter to who adopts and when.

关键词： Technology Adoption Water Irrigation Natural Resources

Modeling Resource Use Responses to Macroeconomic Changes: Water in the US Southern Great Plains

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Natural Resources 2013年第1期4卷 8-19页

作者： Justin Weinheimer Erin Wheeler-Cook Don Ethridge darren hudson Department of Agricultural and Applied Economics Texas Tech University Lubbock USA

This study addressed the impacts of the 2008 US recession on water extraction rates from the Ogallala Aquifer in the Southern High Plains of Texas by examining the differences in projected macroeconomic variables and how they impact agricultural production and irrigation water use. The approach used pre- and post-recession FAPRI-based projections of commodity markets and an economic optimization model formulated for the Ogallala Aquifer to simulate water use adjustments. Results indicate that, based on the projections used, the 2008 recession decreased, then increased water use slightly in the representative counties, ceteris paribus, with minimal cumulative effect, and water use responsiveness to economic forces within the region was variable. This analysis also demonstrates that relating policy and economic changes to resource use changes is possible.

关键词： Macroeconomic Impacts Ogallala Aquifer Optimization Recession

Does Climatic Variability Influence Agricultural Land Prices under Differing Uses? The Texas High Plains Case

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Natural Resources 2013年第8期4卷 506-513页

作者： Rachna Tewari Jeff Johnson darren hudson Chenggang Wang Dennis Patterson Department of Agricultural and Applied Economics Texas Tech University Lubbock USA Department of Agriculture Geosciences and Natural Resources The University of Tennessee at Martin Martin USA Department of Political Science Texas Tech University Lubbock USA

The Texas High Plains faces projections of increasing temperature and declining precipitation in the future on account of its semi-arid climate. This research evaluated the impact of climatic variability on agricultural land prices under different land uses in the Texas High Plains, employing the Ricardian approach of land climate pricing over a study period of 1991-2011. The results indicate that climatic variability had a greater impact on irrigated land prices as compared to dryland and ranchland. This study could be instrumental in predictive market analyses of rural land values in semi-arid economies which are vulnerable to future climate change.

关键词： Climatic Variability Dryland Irrigated Land Land Prices Ranchland Texas High Plains

Toward mid-infrared nonlinear optics applications of silicon carbide microdisks engineered by lateral under-etching[Invited]

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Photonics Research 2018年第5期6卷 I0099-I0106页

作者： DAVID ALLIOUX ALI BELAROUCI darren hudson ERIC MAGI MILAN SINOBAD GUILLAUME BEAUDIN ADRIEN MICHON NEETESH SINGH REGIS OROBTCHOUK CHRISTIAN GRILLET Universite de Lyon Institut des Nanotechnologie de Lyon69131 EcullyFrance Department of Electrical Engineering Universite de SherbrookeSherbrookeQC JIK 2R1Canada School of Physics University of SydneySydneyNSW 2006Australia RMIT School of Electrical and Computer Engineering MelbourneVlC 3000Australia Universite Cote d'Azur CNRSCRHEAFrance

We report the fabrication and characterization of silicon carbide microdisks on top of silicon pillars suited for applications from near-to mid-infrared. We probe 10 μm diameter disks with different under-etching depths,from 4 μm down to 1.4 μm, fabricated by isotropic plasma etching and extract quality factors up to 8400 at telecom wavelength. Our geometry is suited to present high Q single-mode operation. We experimentally demonstrate high-order whispering-gallery mode suppression while preserving the fundamental gallery mode and investigate some requirements for nonlinear optics applications on this platform, specifically in terms of quality factor and dispersion for Kerr frequency comb generation.

关键词： Toward mid-infrared nonlinear optics applications silicon carbide microdisks engineered by lateral under-etching

Computer-animated stimuli to measure motionsensitivity： constraints on signal design in theJacky dragon

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Current Zoology 2017年第1期63卷 75-84页

作者： Kevin L. Woo Guillaume RIEUCAU darren BURKE SUNY Empire State College Metropolitan Center 325 Hudson Street New York NY 10013-1005 USA Department of Biological Sciences Florida International University 3000 Northeast 151 St North Miami FL 33181 USA School of Psychology University of Newcastle 10 Chittaway Road Ourimbah New South Wales 2258Australia

Identifying perceptual thresholds is critical for understanding the mechanisms that underlie signalevolution. Using computer-animated stimuli, we examined visual speed sensitivity in the Jackydragon Amphibolurus muricatus, a species that makes extensive use of rapid motor patterns in so-cial communication. First, focal lizards were tested in discrimination trials using random-dot kine-matograms displaying combinations of speed, coherence, and direction. Second, we measuredsubject lizards＇ ability to predict the appearance of a secondary reinforcer （1 of 3 differentcomputer-generated animations of invertebrates： cricket, spider, and mite） based on the directionof movement of a field of drifting dots by following a set of behavioural responses （e.g., orientingresponse, latency to respond） to our virtual stimuli. We found an effect of both speed and coher-ence, as well as an interaction between these 2 factors on the perception of moving ***, our results showed that Jacky dragons have acute sensitivity to high speeds. We then em-ployed an optic flow analysis to match the performance to ecologically relevant motion. Our resultssuggest that the Jacky dragon visual system may have been shaped to detect fast motion. Thispre-existing sensitivity may have constrained the evolution of conspecific displays. In contrast,Jacky dragons may have difficulty in detecting the movement of ambush predators, such as snakesand of some invertebrate prey. Our study also demonstrates the potential of the computer-animated stimuli technique for conducting nonintrusive tests to explore motion range and sensitiv-ity in a visually mediated species.

关键词： Amphibolurus muricatus, Jacky dragon, motion sensitivity, random-dot kinematograms, signal evolution, virtualstimuli.