TY - JOUR TI - A Space/Time Analysis Framework for Fecal Indicator Bacteria in a North Carolina Estuary AU - Coulliette, A. AU - Money, E. AU - Serre, M. AU - Noble, R. T2 - Epidemiology DA - 2008/// PY - 2008/// DO - 10.1097/01.ede.0000340103.90644.88 VL - 19 IS - 6 SP - S200 ER - TY - RPRT TI - Covariance models for directed tree river networks AU - Money, E. AU - Carter, G. AU - Serre, M.L. DA - 2008/// PY - 2008/// M1 - 2008-08 M3 - UNC-BMElab Technical Report SN - 2008-08 ER - TY - CONF TI - Geostatistical Estimation of Water Quality Along River Networks AU - Money, E. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2008/// C3 - North Carolina Water Resources Research Institute Annual Conference CY - Raleigh, NC, USA DA - 2008/// PY - 2008/10/8/ ER - TY - CONF TI - An Integrated Spatiotemporal Approach to Improve Mercury Estimation and Exposure Assessment AU - Money, E. AU - Sackett, D.K. AU - Aday, D. AU - Serre, M.L. T2 - International Society for Environmental Epidemiology & International Society of Exposure Analysis Joint Annual Conference C2 - 2008/// C3 - International Society for Environmental Epidemiology & International Society of Exposure Analysis Joint Annual Conference CY - Pasadena, CA, USA DA - 2008/// PY - 2008/10/12/ ER - TY - CONF TI - Improving the Assessment of E.coli Exposure Levels Along Un-monitored Stream Reaches AU - Money, E. AU - Carter, G.P. AU - Serre, M.L. T2 - International Society for Environmental Epidemiology & International Society of Exposure Analysis, 2008 Joint Annual Conference C2 - 2008/// C3 - International Society for Environmental Epidemiology & International Society of Exposure Analysis, 2008 Joint Annual Conference CY - Pasadena, CA, USA DA - 2008/// PY - 2008/10/12/ ER - TY - CONF TI - Overwintering Habitats of the Colorado potato beetle in Wisconsin's Central Sands Production Area AU - Huseth, A.S. AU - Groves, R.L. T2 - Wisconsin Potato and Vegetable Growers Association, Grower Education Conference C2 - 2008/// C3 - Proceedings of the Wisconsin Potato and Vegetable Growers Association, Grower Education Conference CY - Stevens Point, WI DA - 2008/// PY - 2008/2/5/ VL - 21 SP - 29-32 ER - TY - THES TI - Tectonic Geomorphology above Mediterranean Subduction Zones: Northeastern Apennines of Italy and Crete, Greece AU - Wegmann, K.W. DA - 2008/// PY - 2008/// SP - 169 M3 - Ph.D. Dissertation PB - Lehigh University ER - TY - SOUND TI - Is this Climate Change Story True? AU - Cooper, C.B. DA - 2008/11/12/ PY - 2008/11/12/ ER - TY - SOUND TI - Media Bytes: Is this Climate Change Story True? AU - Cooper, C.B. DA - 2008/4/17/ PY - 2008/4/17/ ER - TY - NEWS TI - Looking for the perfect fixer-upper: Chickadees prefer nest tubes filled with wood shavings more than boxes T2 - Birdscope C2 - summer PY - 2008/6// PB - Cornell Lab of Ornithology ER - TY - CONF TI - An Agent-Based Simulation-Optimization Approach to Identify Threat Management Strategies for Water Distribution Systems AU - Zechman, Emily M. T2 - World Environmental and Water Resources Congress 2008 AB - Threat management decisions in the event of contamination of a water distribution system must be tailored to protect public health, maintain fire-fighting flows and flows to critical care facilities, and avoid inciting panic due to false alarms. Threat management strategies may be composed as a set of rules for taking actions to mitigate the situation and protect public health, such as flushing the water distribution system by opening fire hydrants or inducing demands, isolating portions of the system using control valves, and broadcasting boil water orders. These strategies must be robust to control contamination events that vary in time of injection, duration, and mass flow profiles, as well as to avoid false alarms. The development of threat management strategies can be improved through the use of a simulation-optimization framework that simulates the complex interactions between managers' operation decisions, consumers' water consumption choices and the response of the hydraulics and contaminant transport in the water distribution system through mechanistic and dynamic methods enabled by agent-based models. Heuristic optimization methods are coupled within the dynamic system simulation framework to allow identification of efficient threat management strategies to achieve public health protection and maintain acceptable service. These methods will be explored for an illustrative case study to identify strategies to achieve these objectives. C2 - 2008/5// C3 - World Environmental and Water Resources Congress 2008 DA - 2008/5// DO - 10.1061/40976(316)506 PB - American Society of Civil Engineers SN - 9780784409763 UR - http://dx.doi.org/10.1061/40976(316)506 DB - Crossref ER - TY - CONF TI - Addressing Non-uniqueness in a Water Distribution Contaminant Source Identification Problem AU - Zechman, Emily M. AU - Brill, Jr., E. Downey AU - Mahinthakumar, G. AU - Ranjithan, S. AU - Uber, James T2 - Eighth Annual Water Distribution Systems Analysis Symposium (WDSA) AB - The source of contamination in a water distribution system may be identified through a simulation-optimization approach. The optimization method searches for the contaminant source characteristics by iteratively estimating the contaminant plume concentrations until they match observations at sensors. The amount of information available for characterizing the source depends on the number and spatial locations of the sensors, as well as on the temporally varying stream of sensed data. The accuracy of the source characterization depends on the amount of observations available. A major factor affecting, this accuracy is the degree of non-uniqueness present in the problem, which may cause misidentification of the source characteristics. As more sensors are added to the network, the non-uniqueness may be reduced and a unique solution may be identified. Thus, a key consideration when solving these problems is to assess whether the solution identified is unique, and if not, what other possible solutions are present. A systematic search for a set of alternatives that are maximally different in solution characteristics can be used to address and quantify non-uniqueness. For example, if the most different set of solutions that are identified by a search procedure are very similar, then that solution will be considered as the unique solution with a higher degree of certainty. Alternatively, identification of a set of maximally different solutions that vary widely in solution characteristics will indicate that non-uniqueness is present in the problem, and the range of solutions can be used as a general representation of the amount of non-uniqueness. This paper investigates the use of evolutionary algorithm (EA)-based alternatives generation procedures to quantify and address non-uniqueness present in a contaminant source identification problem for a water distribution network. As additional sensors may decrease the amount of non-uniqueness, several sensor configurations will be tested to investigate and quantify the improvement in uniqueness as more information is used in the source characterization. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF). C2 - 2008/3/13/ C3 - Water Distribution Systems Analysis Symposium 2006 DA - 2008/3/13/ DO - 10.1061/40941(247)126 PB - American Society of Civil Engineers SN - 9780784409411 UR - http://dx.doi.org/10.1061/40941(247)126 DB - Crossref ER - TY - CONF TI - Adaptive Contamination Source Identification in Water Distribution Systems Using an Evolutionary Algorithm-based Dynamic Optimization Procedure AU - Liu, Li AU - Zechman, Emily M. AU - Brill, Jr., E. Downey AU - Mahinthakumar, G. AU - Ranjithan, S. AU - Uber, James T2 - Eighth Annual Water Distribution Systems Analysis Symposium (WDSA) AB - Accidental drinking water contamination has long been and remains a major threat to water security throughout the world. Consequently, contamination source identification is an important and difficult problem in the managing safety in water distribution systems. This problem involves the characterization of the contaminant source based on observations that are streaming from a set of sensors in the distribution network. Since contamination spread in a water distribution network is relatively quick and unpredictable, rapid identification of the source location and related characteristics is important to take contaminant control and containment actions. As the contaminant event unfolds, the streaming data could be processed over time to adoptively estimate the source characteristics. This provides an estimate of the source characteristics at any time after a contamination event is detected, and this estimate is continually updated as new observations become available. We pose and solve this problem using a dynamic optimization procedure that could potentially provide a real-time response. As time progresses, additional data is observed at a set of sensors, changing the vector of observations that should be predicted. Thus, the prediction error function, is updated dynamically, changing the objective function in the optimization model. We investigate a new multi population-based search using an evolutionary algorithm (EA) that at any time represents the solution state that best matches the available observations. The set of populations migrates to represent updated solution states as new observations are added over time. At the initial detection period, non-uniqueness is inherent in the source-identification due to inadequate information, and, consequently, several solutions may predict similarly well. To address non-uniqueness at the initial stages of the search and prevent premature convergence of the EA to an incorrect solution, the multiple populations in the proposed methodology are designed to maintain a set of alternative solutions representing different non-unique solutions. As more observations are added, the EA solutions not only migrate to better solution states, but also reduce the number of solutions as the degree of non-uniqueness diminishes. This new dynamic optimization algorithm adoptively converges to the best solution(s) to match the observations available at any time. The new method will be demonstrated for a contamination source identification problem in an illustrative water distribution network. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF). C2 - 2008/3/13/ C3 - Water Distribution Systems Analysis Symposium 2006 DA - 2008/3/13/ DO - 10.1061/40941(247)123 PB - American Society of Civil Engineers SN - 9780784409411 UR - http://dx.doi.org/10.1061/40941(247)123 DB - Crossref ER - TY - SOUND TI - Role of Climate Forecasts in Meeting NC Future Water Supply Challenges AU - Arumugam, S. DA - 2008/1/19/ PY - 2008/1/19/ ER - TY - CONF TI - Improving Hydrological Predictions through better representation of Model Uncertainty AU - Li, W. AU - Arumugam, S. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2008/10// CY - Raleigh, NC DA - 2008/10// PY - 2008/10// ER - TY - CONF TI - Role of Streamflow Seasonality in Influencing Water Quality Variability in the Southeastern US AU - Oh, J. AU - Arumugam, S. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2008/10// CY - Raleigh, NC DA - 2008/10// PY - 2008/10// ER - TY - CONF TI - Improved Drought Management of Falls Lake Reservoir: Role of Multimodel Streamflow Forecasts in Setting up Restrictions AU - Devineni, N. AU - Arumugam, S. T2 - North Carolina Water Resources Research Institute Annual Conference C2 - 2008/10// CY - Raleigh, NC DA - 2008/10// PY - 2008/10// ER - TY - CONF TI - The Role of Multimodel Combinations in improving Streamflow Prediction AU - Arumugam, S. AU - Li, W. T2 - American Geophysical Union Fall Meeting C2 - 2008/// CY - San Francisco, CA DA - 2008/// PY - 2008/12/15/ ER - TY - JOUR TI - Artificial nest site preferences of Black-capped Chickadees AU - Cooper, Caren AU - Bonter, David T2 - Journal of Field Ornithology AB - ABSTRACT To facilitate study of the breeding biology of parids, Grubb and Bronson (1995; Condor 97: 1067–1070) designed artificial “snags” made from polyvinyl chloride (PVC) tubes. Because the cost of artificial snags is greater than that of traditional wooden boxes, we examined alternatives to PVC snags for attracting chickadees to artificial nesting sites. From 2005 to 2007, we compared the use of PVC snags and wooden nest boxes by Black-capped Chickadees (Poecile atricapillus) in Sapsucker Woods Sanctuary in Ithaca, New York. We also quantified the use of cavities with and without wood shavings. The probability of chickadee excavation was greater (60–70% per yr) in filled snags (with wood shavings) than in filled boxes (40–50%; logistic mixed model, P= 0.01), and chickadees initiated more nests in filled snags (25–30%) than filled boxes (15%; P= 0.03). Chickadees also initiated significantly more nests (P= 0.03) in filled than unfilled boxes. Although wooden boxes filled with wood shavings were used more often by Black-capped Chickadees than unfilled wooden boxes, artificial snags filled with wood shavings were used most, were no more likely than boxes to be usurped by House Wrens (Troglodytes aedon), and were less likely than boxes to be occupied by mice. Thus, artificial snags may be the better option for investigators studying the breeding biology of chickadees. Para facilitar estudios sobre la biología reproductiva de los paridos, Grubb and Bronson (1995; Condor 97: 1067–1070) diseñaron “tocones” artificiales hechos de tubos de policloruro de vinilo (PVC). Debido a que el costo de los tocones artificiales es mayor que el de las cajas de madera tradicionales, examinamos las alternativas a los tocones de PVC para atraer a Poecile atricapillus a lugares artificiales de anidación. Entre el 2005 y el 2007, comparamos el uso de tocones de PVC y cajas de madera por P. atricapillus en el santuario de Sapsucker Woods en Ithaca, Nueva York. También cuantificamos el uso de cavidades con y sin aserrín de madera. La probabilidad de excavación por P. atricapillus fue mayor (60–70% por año) en tocones con aserrín que en cajas con aserrín (40–50%; modelo logístico mixto, P= 0.01), y los individuos comenzaron mas nidos en tocones con aserrín (25–30%) que en cajas con aserrín (15%; P= 0.03). P. atricapillus comenzó significativamente mas nidos (P= 0.03) en cajas con aserrín que en cajas sin aserrín. Aunque las cajas de madera con aserrín en su interior fueron usadas mas frecuentemente por P. atricapillus que cajas de madera vacías, los tocones artificiales con aserrín en su interior fueron mayormente usadas y no tuvieron una mayor probabilidad de ser usurpadas por Troglodytes aedon y también tuvieron una probabilidad mas baja de ser ocupadas por ratones que las cajas. Así, los tocones artificiales pueden ser una mejor opción para investigadores quienes estudian la biología reproductiva de P. atricapillus. DA - 2008/6// PY - 2008/6// DO - 10.1111/j.1557-9263.2008.00162.x VL - 79 IS - 2 SP - 193-197 J2 - J Field Ornithology LA - en OP - SN - 0273-8570 1557-9263 UR - http://dx.doi.org/10.1111/j.1557-9263.2008.00162.x DB - Crossref KW - artificial snag KW - Black-capped Chickadee KW - cavity excavation KW - field experiment KW - nest box ER - TY - JOUR TI - CAN WE IMPROVE ESTIMATES OF JUVENILE DISPERSAL DISTANCE AND SURVIVAL AU - Cooper, Caren B. AU - Daniels, Susan J. AU - Walters, Jeffrey R. T2 - Ecology AB - Estimates of distributions of natal dispersal distances and juvenile recruitment rates in open populations are strongly influenced by the extent and shape of the areas sampled. Techniques to improve biased dispersal and survival estimates include area-ratio methods based on weighting observations by sampling effort, the extent and shape of the area sampled, and the amount and distribution of preferred habitat surrounding the area sampled. We partitioned territories within the boundaries of a large, almost geographically closed, population of individually marked Red-cockaded Woodpeckers (Picoides borealis) and estimated dispersal and survival parameters from hypothetical smaller study areas (sampling areas) of varying sizes and shapes in order to examine whether an area-ratio method provides accurate or improved estimates of juvenile dispersal distance and survival. Non-aggregated sampling areas resulted in the detection of fewer dispersal events, but because of their large spatial extent, produced unbiased dispersal estimates. The use of aggregated sampling areas (circular or linear) resulted in the detection of higher numbers of dispersal events, but produced biased dispersal estimates that were generally improved by the area-ratio method. Area-ratio corrections usually provided better estimates of median dispersal distance than uncorrected estimates. Survival to breeding was usually underestimated and often not improved by the area-ratio method, regardless of extent and shape of the sampling area. Estimates of juvenile survival to breeding were improved by assuming that rates of emigration were equivalent to immigration, and correcting survival estimates accordingly. Small, local studies should use an area-ratio method to improve their estimates of median dispersal distance. Because the correction method estimates relative, but not absolute, numbers of individuals dispersing across distance categories, the area-ratio method should not be used for estimating survival. Non-aggregated sampling areas may be an effective design to increase spatial extent (and thus decrease bias) without proportionately increasing the amount of habitat sampled. DA - 2008/12// PY - 2008/12// DO - 10.1890/08-0315.1 VL - 89 IS - 12 SP - 3349-3361 J2 - Ecology LA - en OP - SN - 0012-9658 UR - http://dx.doi.org/10.1890/08-0315.1 DB - Crossref KW - area-ratio correction KW - band-resight KW - Picoides borealis KW - Red-cockaded Woodpecker KW - study area design ER - TY - JOUR TI - Science Explicitly for Nonscientists AU - Cooper, Caren B. AU - Dickinson, Janis L. AU - Phillips, Tina AU - Bonney, Rick T2 - Ecology and Society DA - 2008/// PY - 2008/// DO - 10.5751/es-02602-1302r01 VL - 13 IS - 2 J2 - E&S LA - en OP - SN - 1708-3087 UR - http://dx.doi.org/10.5751/es-02602-1302r01 DB - Crossref ER - TY - CONF TI - Design for a region-wide adaptive search for the ivorybilled woodpecker with the objective of estimating occupancy and related parameters AU - Cooper, R.J. AU - Mordecai, Rua S. AU - Mattsson, B.G. AU - Conroy, M.J. AU - Pacifici, K. AU - Peterson, J.T. AU - Moore, C.T. C2 - 2008/// C3 - Tundra to Tropics: Connecting Birds, Habitats and People: 4th International Partners in Flight Conference, 13-16 February 2008, McAllen, Texas: Abstracts DA - 2008/// ER - TY - RPRT TI - An Adaptive Sample Survey Design for the Ivory-billed Woodpecker AU - Moore, Clinton T. AU - Mattsson, Brady J. AU - Mordecai, Rua S. AU - Pacifici, Krishna AU - Conroy, Michael J. AU - Peterson, James T. AU - Cooper, Robert J. DA - 2008/3/31/ PY - 2008/3/31/ M1 - 1434-02HQRU1551 M3 - Cooperative Agreement SN - 1434-02HQRU1551 UR - http://usgs-cru-individual-data.s3.amazonaws.com/cmoore/tech_publications/Conroy%20et%20al%20(2008)%20IBWO%20Final%20Report-1.pdf ER - TY - CHAP TI - Evaluating PAH Biodegradation Relative to Total Bacterial Carbon Demand in Coastal Ecosystems: Are PAHs Truly Recalcitrant? AU - Boyd, T.J. AU - Smith, D.C. AU - Apple, J.K. AU - Hamdan, L.J. AU - Osburn, C.L. AU - Montgomery, M.T T2 - Microbial Ecology Research Trends A2 - Van Dijk, T. PY - 2008/// SP - 1–38 PB - NOVA Science Publishers Inc ER - TY - CONF TI - Retrieving LAI from Remotely Sensed Images: Spectral Indices vs Spatial Texture AU - Song, C. AU - Gray, J.M. AU - Zhang, S. C2 - 2008/// C3 - American Geophysical Union, Fall Meeting Abstracts DA - 2008/// SP - B33D-03 PB - American Geophysical Union ER - TY - CHAP TI - Recreation ecology insustainable tourism andecotourism: A strengtheningrole AU - Leung, Y.-F. AU - Marion, J.L. AU - Farrell, T.A. T2 - Tourism, Recreation and Sustainability: Linking Culture and the Environment: Second Edition PY - 2008/// SP - 19-37 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80054699266&partnerID=MN8TOARS ER - TY - JOUR TI - A Coasian Approach to Efficient Water Allocation of a Transboundary River AU - Willis, David B. AU - Baker, Justin S. T2 - Journal of Agricultural and Applied Economics AB - The United States and Mexico recently resolved a decade-old water dispute that required Mexico to repay the accumulated water debt within one year. A Coasian analysis estimates the social welfare gains attainable to each country under an alternative debt repayment scheme that allows repayment over a longer time horizon and in a combination of dollars and water, instead of solely in water. Assuming average water supply conditions, under the agreed 1-year repayment contract, U.S. compensation value is 534% greater and Mexico's compensation cost is 60% less relative to when compensation is paid exclusively in water. DA - 2008/8// PY - 2008/8// DO - 10.1017/s1074070800023762 VL - 40 IS - 2 SP - 473-484 J2 - J. Agric. Appl. Econ. LA - en OP - SN - 1074-0708 2056-7405 UR - http://dx.doi.org/10.1017/s1074070800023762 DB - Crossref ER - TY - JOUR TI - A novel field evaluation of the effectiveness of distance and independent observer sampling to estimate aural avian detection probabilities AU - Alldredge, Mathew W. AU - Pacifici, Krishna AU - Simons, Theodore R. AU - Pollock, Kenneth H. T2 - Journal of Applied Ecology AB - 1 The validation of field sampling techniques is a concern for applied ecologists due to the strong model assumptions implicit in all methods. Computer simulations make replication easy, but they do not give insights into how much bias occurs in real populations. Testing sampling methods on populations of known size can establish directly how well estimators perform, but such populations are very hard to find, and replicate, and they may have unusual attributes. 2 We present a field validation of distance and double-observer methods of estimating detection probabilities on aural avian point counts. Our research is relevant to conservation agencies worldwide who design thousands of avian monitoring programmes based primarily on auditory point counts. The programmes are a critical component in the management of many avian species. 3 Our validation used a simulation system which mimics birds calling in a field environment. The system allowed us to vary singing rate, species, distance, the complexity of points, and other factors. 4 Distance methods performed poorly, primarily due to large localization errors, and estimates did not improve for simplified points. 5 For the double-observer method, two pairs of observers tended to underestimate true population size, while the third pair tended to double-count birds which overestimated the population. Detection probabilities were always higher and population estimates lower when observers subjectively matched birds compared to an objective rule and showed a slight negative bias and good precision. A simplified 45-degree matching rule did not improve the performance of double-observer estimates which had a slight positive bias and much lower precision. Double-observer estimates did improve on the simplified points. 6 Synthesis and applications. We encourage ecologists working with sampling methods to develop similar methods of working with simulated populations through use of technology. Our simulated field evaluation has demonstrated the difficulty of accurately estimating population size when limited to aural detections. Problems are related to limitations in the ability of observers to localize sound, estimate distance, and accurately identify birds during a count. Other sources of error identified are the effects of observers, singing rate, singing orientation and background noise. DA - 2008/10// PY - 2008/10// DO - 10.1111/j.1365-2664.2008.01517.x VL - 45 IS - 5 SP - 1349-1356 LA - en OP - SN - 0021-8901 1365-2664 UR - http://dx.doi.org/10.1111/j.1365-2664.2008.01517.x DB - Crossref KW - avian point counts KW - aural detections KW - detection probability KW - distance sampling KW - field tests KW - multiple observers ER - TY - JOUR TI - EFFECTS OF VEGETATION AND BACKGROUND NOISE ON THE DETECTION PROCESS IN AUDITORY AVIAN POINT-COUNT SURVEYS AU - Pacifici, Krishna AU - Simons, Theodore R. AU - Pollock, Kenneth H. T2 - The Auk AB - We used a bird-song simulation system to experimentally assess the effects of habitat, vegetation structure, and background noise on detection probability in aural avian point counts. We simulated bird songs of seven species in two habitats (mixed pine–hardwood forest and deciduous forest) and two leaf conditions (leaves on and leaves off) with two levels of background noise (~40 dB and ~50 dB). Estimated detection probabilities varied greatly among species, and complex interactions among all the factors existed. Background noise and the presence of leaves on trees decreased detection probabilities, and estimated detection probabilities were higher in mixed pine–hardwood forest than in deciduous forest. At 100 m, average estimated detection probabilities ranged from 0 to 1 and were lowest for the Black-and-white Warbler (Mniotilta varia) and highest for the Brown Thrasher (Toxostoma rufum). Simulations of expected counts, based on the best logistic model, indicated that observers detect between 3% (for the worst observer, least detectable species, with leaves on the trees and added background noise in the deciduous forest) and 99% (for the best observer, most detectable species, with no leaves on the trees and no added background noise in the mixed forest) of the total count. The large variation in expected counts illustrates the importance of estimating detection probabilities directly. The large differences in detection probabilities among species suggest that tailoring monitoring protocols to specific species of interest may produce better estimates than a single protocol applied to a wide range of species. DA - 2008/7// PY - 2008/7// DO - 10.1525/auk.2008.07078 VL - 125 IS - 3 SP - 600-607 J2 - The Auk LA - en OP - SN - 0004-8038 1938-4254 UR - http://dx.doi.org/10.1525/auk.2008.07078 DB - Crossref KW - aural detections KW - background noise KW - detection probability KW - habitat effects KW - point counts KW - population indices ER - TY - JOUR TI - Exurbia from the bottom-up: Confronting empirical challenges to characterizing a complex system AU - Brown, Daniel G. AU - Robinson, Derek T. AU - An, Li AU - Nassauer, Joan I. AU - Zellner, Moira AU - Rand, William AU - Riolo, Rick AU - Page, Scott E. AU - Low, Bobbi AU - Wang, Zhifang T2 - Geoforum AB - We describe empirical results from a multi-disciplinary project that support modeling complex processes of land-use and land-cover change in exurban parts of Southeastern Michigan. Based on two different conceptual models, one describing the evolution of urban form as a consequence of residential preferences and the other describing land-cover changes in an exurban township as a consequence of residential preferences, local policies, and a diversity of development types, we describe a variety of empirical data collected to support the mechanisms that we encoded in computational agent-based models. We used multiple methods, including social surveys, remote sensing, and statistical analysis of spatial data, to collect data that could be used to validate the structure of our models, calibrate their specific parameters, and evaluate their output. The data were used to investigate this system in the context of several themes from complexity science, including have (a) macro-level patterns; (b) autonomous decision making entities (i.e., agents); (c) heterogeneity among those entities; (d) social and spatial interactions that operate across multiple scales and (e) nonlinear feedback mechanisms. The results point to the importance of collecting data on agents and their interactions when producing agent-based models, the general validity of our conceptual models, and some changes that we needed to make to these models following data analysis. The calibrated models have been and are being used to evaluate landscape dynamics and the effects of various policy interventions on urban land-cover patterns. DA - 2008/3// PY - 2008/3// DO - 10.1016/j.geoforum.2007.02.010 VL - 39 IS - 2 SP - 805-818 J2 - Geoforum LA - en OP - SN - 0016-7185 UR - http://dx.doi.org/10.1016/j.geoforum.2007.02.010 DB - Crossref KW - urban sprawl KW - land-cover change KW - land-use change KW - spatial modeling KW - ecological effects ER - TY - JOUR TI - Reciprocity between the cerebellum and the cerebral cortex: Nonlinear dynamics in microscopic modules for generating voluntary motor commands AU - Wang, Jun AU - Dam, Gregory AU - Yildirim, Sule AU - Rand, William AU - Wilensky, Uri AU - Houk, James C. T2 - Complexity AB - Abstract The cerebellum and basal ganglia are reciprocally connected with the cerebral cortex, forming many loops that function as distributed processing modules. Here we present a detailed model of one microscopic loop between the motor cortex and the cerebellum, and we show how small arrays of these microscopic loops (CB modules) can be used to generate biologically plausible motor commands for controlling movement. A fundamental feature of CB modules is the presence of positive feedback loops between the cerebellar nucleus and the motor cortex. We use nonlinear dynamics to model one microscopic loop and to investigate its bistable properties. Simulations demonstrate an ability to program a motor command well in advance of command generation and an ability to vary command duration. However, control of command intensity is minimal, which could interfere with the control of movement velocity. To assess these hypotheses, we use a minimal nonlinear model of the neuromuscular (NM) system that translates motor commands into actual movements. Simulations of the combined CB‐NM modular model indicate that movement duration is readily controlled, whereas velocity is poorly controlled. We then explore how an array of eight CB‐NM modules can be used to control the direction and endpoint of a planar movement. In actuality, thousands of such microscopic loops function together as an array of adjustable pattern generators for programming and regulating the composite motor commands that control limb movements. We discuss the biological plausibility and limitations of the model. We also discuss ways in which an agent‐based representation can take advantage of the modularity in order to model this complex system. © 2008 Wiley Periodicals, Inc. Complexity, 2008 DA - 2008/11// PY - 2008/11// DO - 10.1002/cplx.20241 VL - 14 IS - 2 SP - 29-45 J2 - Complexity LA - en OP - SN - 1076-2787 1099-0526 UR - http://dx.doi.org/10.1002/cplx.20241 DB - Crossref KW - neural network KW - motor cortex KW - cerebellum KW - movement KW - nonlinear dynamics KW - motor command KW - equilibrium point control KW - agent-based modeling ER - TY - CHAP TI - A Learning Scheme for Recognizing Sub-classes from Model Trained on Aggregate Classes AU - Vatsavai, Ranga Raju AU - Shekhar, Shashi AU - Bhaduri, Budhendra T2 - Lecture Notes in Computer Science AB - In many practical situations it is not feasible to collect labeled samples for all available classes in a domain. Especially in supervised classification of remotely sensed images it is impossible to collect ground truth information over large geographic regions for all thematic classes. As a result often analysts collect labels for aggregate classes. In this paper we present a novel learning scheme that automatically learns sub-classes from the user given aggregate classes. We model each aggregate class as finite Gaussian mixture instead of classical assumption of unimodal Gaussian per class. The number of components in each finite Gaussian mixture are automatically estimated. Experimental results on real remotely sensed image classification showed not only improved accuracy in aggregate class classification but the proposed method also recognized sub-classes. PY - 2008/// DO - 10.1007/978-3-540-89689-0_100 SP - 967-976 OP - PB - Springer Berlin Heidelberg SN - 9783540896883 9783540896890 UR - http://dx.doi.org/10.1007/978-3-540-89689-0_100 DB - Crossref ER - TY - JOUR TI - Space Syntax and Walking in a New Urbanist and Suburban Neighbourhoods AU - Baran, Perver K. AU - Rodríguez, Daniel A. AU - Khattak, Asad J. T2 - Journal of Urban Design AB - Prevailing measures of street design have largely ignored the relational properties between local and global street design as correlates of walking behaviour. This study contributes to understanding relationships between the syntactical properties of street design and walking behaviour by examining whether space syntax measures in New Urbanist and conventional suburban neighbourhoods are associated with the walking patterns of residents in these communities. Relying on geographic information systems, survey data and travel diaries, the study relates control, local integration and global integration to walking behaviour, while adjusting for the effect of individual- and household-level characteristics. It finds significant relationships between the number of leisure trips and all three syntactical measures. It also finds a consistent positive relationship between total utilitarian walking and two of the space syntax variables, control and global integration. By explaining individuals' walking behaviour using relational measures of street design, urban designers and planners are encouraged to expand their consideration of how street design may influence walking beyond the local purview. DA - 2008/2// PY - 2008/2// DO - 10.1080/13574800701803498 VL - 13 IS - 1 SP - 5-28 J2 - Journal of Urban Design LA - en OP - SN - 1357-4809 1469-9664 UR - http://dx.doi.org/10.1080/13574800701803498 DB - Crossref ER - TY - JOUR TI - Seismic identification of along-axis hydrothermal flow on the East Pacific Rise AU - Tolstoy, M. AU - Waldhauser, F. AU - Bohnenstiehl, D. R. AU - Weekly, R. T. AU - Kim, W.-Y. T2 - Nature DA - 2008/1// PY - 2008/1// DO - 10.1038/nature06424 VL - 451 IS - 7175 SP - 181-184 J2 - Nature LA - en OP - SN - 0028-0836 1476-4687 UR - http://dx.doi.org/10.1038/nature06424 DB - Crossref ER - TY - JOUR TI - An Approach to the Study of Transport and Dispersion of Threat Agents in a Subway Station AU - Richmond-Bryant, Jennifer AU - Wittig, Ann E. T2 - Journal of Applied Security Research AB - The objective of the proposed research is to assess the exposure of subway riders and workers to threat agents introduced in the subway environment. This article presents the study plan, considerations, and expected outcomes of a novel approach to study this issue. A modular scale model of a subway station has been erected from Metropolitan Transportation Authority of New York design specifications. This model will be used in a series of experiments to analyze airflow and dispersion patterns in the wake of a moving train and in an empty tunnel. Particle image velocimetry will be used to measure transient velocity profiles and concentration profiles. DA - 2008/12/23/ PY - 2008/12/23/ DO - 10.1080/19361610802210210 VL - 4 IS - 1-2 SP - 68-78 J2 - Journal of Applied Security Research LA - en OP - SN - 1936-1610 1936-1629 UR - http://dx.doi.org/10.1080/19361610802210210 DB - Crossref KW - Dispersion KW - exposure assessment KW - fluid dynamics KW - New York City KW - particle image velocimetry KW - scale model KW - security KW - subway KW - threat agents ER - TY - JOUR TI - Tidal marshes as a source of optically and chemically distinctive colored dissolved organic matter in the Chesapeake Bay AU - Tzortziou, Maria AU - Neale, Patrick J. AU - Osburn, Christopher L. AU - Megonigal, J. Patrick AU - Maie, Nagamitsu AU - Jaffé, Rudolf T2 - Limnol. Oceangr. AB - The role of tidal marshes as a source of dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) for adjacent estuarine waters was studied in the Rhode River subestuary of the Chesapeake Bay. Water in a tidal creek draining brackish, high‐elevation marshes was sampled every hour during several semidiurnal tidal cycles in order to examine the tidal exchange of dissolved organic matter (DOM). Water leaving the marsh during ebbing tide was consistently enriched in DOC compared to water entering the marsh during flooding tide. There was a net DOC export from the marsh to the estuary during seasons of both low and high marsh plant biomass. Optical analysis demonstrated that, in addition to contributing to the carbon budgets, the marsh had a strong influence on the estuary’s CDOM dynamics. Marsh‐exported CDOM had optical properties that were consistently and markedly different from those of CDOM in the adjacent estuary. Specifically, marsh CDOM had: (1) considerably stronger absorption, (2) larger DOC‐specific absorption, (3) lower exponential spectral slope, (4) larger fluorescence signal, (5) lower fluorescence per unit absorbance, and (6) higher fluorescence at wavelengths >400 nm. These optical characteristics are indicative of relatively complex, high‐molecular‐weight, aromatic‐rich DOM, and this was confirmed by results of molecular‐weight‐distribution analysis. Our findings illustrate the importance of tidal marshes as sources of optically and chemically distinctive dissolved organic compounds, and their influence on CDOM dynamics, DOC budgets, and, thus, photochemical and biogeochemical processes, in adjacent estuarine ecosystems. DA - 2008/// PY - 2008/// DO - 10.4319/lo.2008.53.1.0148 VL - 53 IS - 1 SP - 148-159 ER - TY - JOUR TI - Bacterial production and microbial food web structure in a large arctic river and the coastal Arctic Ocean AU - Vallières, Catherine AU - Retamal, Leira AU - Ramlal, Patricia AU - Osburn, Christopher L. AU - Vincent, Warwick F. T2 - Journal of Marine Systems AB - Globally significant quantities of organic carbon are stored in northern permafrost soils, but little is known about how this carbon is processed by microbial communities once it enters rivers and is transported to the coastal Arctic Ocean. As part of the Arctic River-Delta Experiment (ARDEX), we measured environmental and microbiological variables along a 300 km transect in the Mackenzie River and coastal Beaufort Sea, in July–August 2004. Surface bacterial concentrations averaged 6.7 × 105 cells mL− 1 with no significant differences between sampling zones. Picocyanobacteria were abundant in the river, and mostly observed as cell colonies. Their concentrations in the surface waters decreased across the salinity gradient, dropping from 51,000 (river) to 30 (sea) cells mL− 1. There were accompanying shifts in protist community structure, from diatoms, cryptophytes, heterotrophic protists and chrysophytes in the river, to dinoflagellates, prymnesiophytes, chrysophytes, prasinophytes, diatoms and heterotrophic protists in the Beaufort Sea. Size-fractionated bacterial production, as measured by 3H–leucine uptake, varied from 76 to 416 ng C L− 1 h− 1. The contribution of particle-attached bacteria (> 3 µm fraction) to total bacterial production decreased from > 90% at the Mackenzie River stations to < 20% at an offshore marine site, and the relative importance of this particle-based fraction was inversely correlated with salinity and positively correlated with particulate organic carbon concentrations. Glucose enrichment experiments indicated that bacterial metabolism was carbon limited in the Mackenzie River but not in the coastal ocean. Prior exposure of water samples to full sunlight increased the biolability of dissolved organic carbon (DOC) in the Mackenzie River but decreased it in the Beaufort Sea. Estimated depth-integrated bacterial respiration rates in the Mackenzie River were higher than depth-integrated primary production rates, while at the marine stations bacterial respiration rates were near or below the integrated primary production rates. Consistent with these results, PCO2 measurements showed surface water supersaturation in the river (mean of 146% of air equilibrium values) and subsaturation or near-saturation in the coastal sea. These results show a well-developed microbial food web in the Mackenzie River system that will likely convert tundra carbon to atmospheric CO2 at increasing rates as the arctic climate continues to warm. DA - 2008/// PY - 2008/// DO - 10.1016/j.jmarsys.2007.12.002 VL - 74 IS - 3-4 SP - 756-773 ER - TY - JOUR TI - Increased Capacity for Polycyclic Aromatic Hydrocarbon Mineralization in Bioirrigated Coastal Marine Sediments AU - Montgomery, Michael T. AU - Osburn, Christopher L. AU - Furukawa, Yoko AU - Gieskes, Joris M. T2 - Bioremediation Journal AB - ABSTRACT Bioirrigation of marine sediments by benthic infauna has the potential to increase both the rate and depth of bacterial mineralization of polycyclic aromatic hydrocarbons (PAHs) by recirculating oxygenated bottom water into sediment burrows. Rates of heterotrophic bacterial production and mineralization of PAHs (naphthalene, phenanthrene, and fluoranthene) were measured in sections of sediment cores sampled from stations in San Diego Bay. Data suggest that rates of PAH biodegradation and bacterial heterotrophy were influenced by bioirrigation by benthic infauna. PAH mineralization and heterotrophic production were higher in core sections where sulfide was not detected relative to core sections containing sulfide. Depth-integrated capacity of the upper 17 cm of sediment to mineralize PAHs was 4 to 10 times higher at the station with bioirrigation coefficients that increased with depth. Remedial dredging of sediments to remove contaminant mass (and presumable lower ecological risk) will also remove benthic infauna. Removal of infauna and the subsequent lowering of bioirrigation in surface sediments would be expected to lower the capacity of intrinsic PAH bioremediation. This could cause local increases in ambient PAH concentration and consequently increase the ecological risk at the site and potentially degrade the health of the ecosystem by removing a sink for PAHs. DA - 2008/5// PY - 2008/5// DO - 10.1080/10889860802060469 VL - 12 IS - 2 SP - 98-110 ER - TY - JOUR TI - Insights into the Interactions between Educational Messages: Looking across Multiple Organizations Addressing Water Issues in Maricopa County, Arizona AU - Cutts, Bethany AU - Saltz, Charlene AU - Elser, Monica T2 - Applied Environmental Education & Communication AB - The public receives environmental information from a variety of sources. Evaluation of a single program or one organization's effort is incomplete. Through surveys and interviews, we evaluate the cumulative impact of outreach by 20 water-related organizations in Maricopa County, Arizona. Household water conservation is a topic addressed by 18 organizations whereas 2 share information on water policy. Similar foci across organizations may help reinforce messages about water conservation, quality, or drought, but can also lead to gaps in water education. These gaps may decrease the relevance of water information to some audiences. Future research should examine additional ways that interorganizational relationships affect the geography of information opportunities and its relevance to unique populations. DA - 2008/8/18/ PY - 2008/8/18/ DO - 10.1080/15330150802194904 VL - 7 IS - 1-2 SP - 40-50 J2 - Applied Environmental Education & Communication LA - en OP - SN - 1533-015X 1533-0389 UR - http://dx.doi.org/10.1080/15330150802194904 DB - Crossref ER - TY - JOUR TI - Distribution and toxigenicity of Aspergillus species isolated from maize kernels from three agro-ecological zones in Nigeria AU - Atehnkeng, J. AU - Ojiambo, P.S. AU - Donner, M. AU - Ikotun, T. AU - Sikora, R.A. AU - Cotty, P.J. AU - Bandyopadhyay, R. T2 - International Journal of Food Microbiology DA - 2008/// PY - 2008/// VL - 122 IS - 1-2 SP - 74-84 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-39149087032&partnerID=MN8TOARS ER - TY - JOUR TI - Partitioning vegetation response to anthropogenic stress to develop multi-taxa indicators of wetland condition AU - Johnston, Carol A. AU - Ghioca, Dana M. AU - Tulbure, Mirela AU - Bedford, Barbara L. AU - Bourdaghs, Michael AU - Frieswyk, Christin B. AU - Vaccaro, Lynn AU - Zedler, Joy B. T2 - Ecological Applications AB - Emergent plants can be suitable indicators of anthropogenic stress in coastal wetlands if their responses to natural environmental variation can be parsed from their responses to human activities in and around wetlands. We used hierarchical partitioning to evaluate the independent influence of geomorphology, geography, and anthropogenic stress on common wetland plants of the U.S. Great Lakes coast and developed multi‐taxa models indicating wetland condition. A seven‐taxon model predicted condition relative to watershed‐derived anthropogenic stress, and a four‐taxon model predicted condition relative to within‐wetland anthropogenic stressors that modified hydrology. The Great Lake on which the wetlands occurred explained an average of about half the variation in species cover, and subdividing the data by lake allowed us to remove that source of variation. We developed lake‐specific multi‐taxa models for all of the Great Lakes except Lake Ontario, which had no plant species with significant independent effects of anthropogenic stress. Plant responses were both positive (increasing cover with stress) and negative (decreasing cover with stress), and plant taxa incorporated into the lake‐specific models differed by Great Lake. The resulting models require information on only a few taxa, rather than all plant species within a wetland, making them easier to implement than existing indicators. DA - 2008/6// PY - 2008/6// DO - 10.1890/07-1207.1 VL - 18 IS - 4 SP - 983-1001 SN - 1051-0761 UR - http://dx.doi.org/10.1890/07-1207.1 KW - carex KW - dikes KW - emergent KW - fen KW - floristic quality KW - Great Lakes KW - hydrologic modification KW - invasive plants KW - land use KW - lemnids KW - marsh KW - Typha ER - TY - JOUR TI - Assessing the use of multiseason QuickBird imagery for mapping invasive species in a Lake Erie coastal Marsh AU - Ghioca-Robrecht, Dana M. AU - Johnston, Carol A. AU - Tulbure, Mirela G. T2 - Wetlands DA - 2008/12// PY - 2008/12// DO - 10.1672/08-34.1 VL - 28 IS - 4 SP - 1028-1039 J2 - Wetlands LA - en OP - SN - 0277-5212 1943-6246 UR - http://dx.doi.org/10.1672/08-34.1 DB - Crossref KW - Phragmites KW - remote sensing KW - Typha KW - wetland mapping ER - TY - JOUR TI - Effect of interannual and interdecadal climate oscillations on groundwater in North Carolina AU - Anderson, William P., Jr. AU - Emanuel, Ryan E. T2 - Geophysical Research Letters AB - Multi‐year climate oscillations such as the El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) affect precipitation and stream discharge rates in the western hemisphere. While inferences may be drawn between these hydroclimatological relationships and groundwater conditions, few studies explicitly link groundwater conditions to these cycles. Here we investigate relationships between winter ENSO, PDO, and lagging baseflow rates in the southeastern United States. We find strong correlation between winter ENSO and lagged baseflow in coastal North Carolina which, coupled with anomalies in mean baseflow, decrease with distance inland from the coast. Our results demonstrate that interannual and interdecadal climate oscillations in the Pacific Ocean have a strong effect on hydrological processes in eastern North America despite filtering by the groundwater flow process. These results have implications for water resource availability in regions where water management is complicated by population growth and climatic uncertainty. DA - 2008/// PY - 2008/// DO - 10.1029/2008GL036054 VL - 35 IS - 23 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000261471200007&KeyUID=WOS:000261471200007 ER - TY - JOUR TI - Homologous bone pin conserved in glycerin at 98% and hernicerclagem with a thread of poliglactina 910 in humerus osteosyntesis of domestic pigeons AU - Bolson, Juliano AU - Wallau Schossler, Joao Eduardo AU - Machado, Gustavo AU - Zembrzuski, Fernanda Boligon T2 - Ciencia Rural AB - O objetivo do presente estudo foi avaliar a utilização de um pino intramedular ósseo homólogo, conservado em glicerina a 98%, associado à hemicerclagem com fio poliglactina 910 na osteossíntese umeral transversa de pombos domésticos (Columba livia). Utilizou-se como pino ósseo a parte distal do tibiotarso, conservado com medula óssea. Foram operados 20 pombos domésticos, adultos, não-sexados e clinicamente sadios. Esses animais foram separados ao acaso em cinco grupos, com quatro indivíduos. O úmero foi seccionado cirurgicamente na sua diáfise, de forma transversa, e o pino ósseo foi devidamente implantado no seio do osso. Orifícios foram realizados e por eles procedeu-se hemicerclagem do tipo pontos de Wolff com poliglactina 910. Os animais foram avaliados clinicamente, por meio de radiografias semanais, e histologicamente após os períodos de 15, 30, 60, 90 e 120 dias. A conservação do pino ósseo em glicerina a 98% foi avaliada por meio de exames microbiológicos. Em todos os animais, pode-se notar, clinicamente, excelente adaptação à cirurgia e normalidade do uso do membro já radiologicamente pode-se observar formação de calo ósseo e cicatrização da fratura. Histologicamente pode-se observar que ocorreu formação de calo ósseo 15 dias após a cirurgia e cicatrização com remodelação completa a partir dos 90 dias. Nesse exame, além de leve a moderada reação inflamatória no período inicial de avaliação, nenhum outro evento foi notado nos períodos subseqüentes. Concluiu-se que a técnica e os materiais utilizados se tornam uma opção altamente viável na osteossíntese umeral transversa de pombos domésticos. DA - 2008/// PY - 2008/// DO - 10.1590/s0103-84782008000700019 VL - 38 IS - 7 SP - 1925-1931 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-54549085568&partnerID=MN8TOARS KW - surgery KW - orthopedics KW - birds KW - bone implant KW - glycerin ER - TY - BOOK TI - Open source GIS: A GRASS GIS approach AU - Neteler, M. AU - Mitasova, H. AB - With this third edition of Open Source GIS: A GRASS GIS Approach, we enter the new era of GRASS6, the first release that includes substantial new code developed by the International GRASS Development DA - 2008/// PY - 2008/// DO - 10.1007/978-0-387-68574-8 SE - 1-406 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892062276&partnerID=MN8TOARS ER - TY - BOOK TI - Chapter Ten Free and Open Source Geospatial Tools for Environmental Modelling and Management AU - Jolma, A. AU - Ames, D.P. AU - Horning, N. AU - Mitasova, H. AU - Neteler, M. AU - Racicot, A. AU - Sutton, T. AB - Geospatial (geographical) software systems (GIS) are used for creating, viewing, managing, analysing and utilising geospatial data. Geospatial data can include socioeconomic, environmental, geophysical, and technical data about the Earth and societal infrastructure and it is pivotal in environmental modelling and management (EMM). Desktop, web-based, and embedded geospatial systems have become an essential part of EMM, providing pre- or post-processing of geospatial data, analysis and visualisation of results or a graphical user interface (GUI). Many local, regional, national, and international efforts are underway to create geospatial data infrastructures and tools for viewing and using geospatial data. When environmental attribute data is linked to these infrastructures, powerful tools for environmental management are instantly created. The growing culture of free/libre and open source software (FOSS) provides an alternative approach to software development for the field of GIS (FOSS4G). To provide an overview of FOSS4G for EMM, we analyse platforms, software stacks, and EMM workflows. In the FOSS world the barriers to interoperability are low and thus the software stack tends to be thicker than in the proprietary platform. The FOSS4G world thrives on the evolution of software stacks and platforms. We provide examples of software stacks built from current FOSS4G that support EMM workflows and highlight the advantages of FOSS4G solutions including opportunities to redistribute resulting modelling tools freely to end-users and to support general goals of openness and transparency with respect to modelling tools. DA - 2008/// PY - 2008/// DO - 10.1016/S1574-101X(08)00610-8 VL - 3 SE - 163-180 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-51449107965&partnerID=MN8TOARS ER - TY - JOUR TI - Simulated effects of climate change, fragmentation, and inter-specific competition on tree species migration in northern Wisconsin, USA AU - Scheller, Robert M. AU - Mladenoff, David J. T2 - CLIMATE RESEARCH AB - CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 36:191-202 (2008) - DOI: https://doi.org/10.3354/cr00745 Simulated effects of climate change, fragmentation, and inter-specific competition on tree species migration in northern Wisconsin, USA Robert M. Scheller1,2,*, David J. Mladenoff1 1Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, Wisconsin 53706, USA 2Present address: Conservation Biology Institute, 136 SW Washington, Suite 202, Corvallis, Oregon 97333, USA *Email: rmscheller@consbio.org ABSTRACT: The reproductive success, growth, and mortality rates of tree species in the northern United States will be differentially affected by projected climate change over the next century. As a consequence, the spatial distributions of tree species will expand or contract at differential rates. In addition, human fragmentation of the landscape may limit effective seed dispersal, and inter-specific competition may limit the migration of climate-adapted species, restraining the rate of tree species migration. If the northward migration of tree species adapted to a warmer climate lags behind the rate of climatic change, overall growth rates and aboveground biomass of northern forests may be significantly reduced relative to their potential. We used a spatially interactive forest landscape model, LANDIS-II, that simulates tree species establishment, growth, mortality, succession, and disturbance. We simulated multiple scenarios of disturbance and climatic change across a ~15000 km2 forested landscape in northwestern Wisconsin, USA. These simulations were used to estimate changes in aboveground live biomass and the spatial distribution of 22 tree species. We observed a reduction in aboveground live biomass relative to the potential biomass for the combined soils and changing climate. We regressed the reduction of potential aboveground biomass against a measure of fragmentation, the initial biomass for 22 tree species, and soil water holding capacity calculated at 3 spatial resolutions. We also regressed the range expansion of 3 individual tree species that are expected to expand their distributions against the same variables. Species migration and range expansion were negatively correlated with fragmentation both in total and for 2 of the 3 species examined in detail. The initial abundances of some tree species were also significant predictors of species migration and range expansion and indicate significant competition between existing species assemblages and more southerly species that are expected to migrate north. In conclusion, the aboveground biomass of northern forests may be limited by interactions among climate change, interspecific competition, and fragmentation. KEY WORDS: Climate change · Forest fragmentation · Interspecific competition · Carbon storage · LANDIS-II · Tree species range expansion · Tree species migration Full text in pdf format PreviousNextCite this article as: Scheller RM, Mladenoff DJ (2008) Simulated effects of climate change, fragmentation, and inter-specific competition on tree species migration in northern Wisconsin, USA. Clim Res 36:191-202. https://doi.org/10.3354/cr00745 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 36, No. 3. Online publication date: June 24, 2008 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2008 Inter-Research. DA - 2008/6/24/ PY - 2008/6/24/ DO - 10.3354/cr00745 VL - 36 IS - 3 SP - 191-202 SN - 0936-577X KW - climate change KW - forest fragmentation KW - interspecific competition KW - carbon storage KW - LANDIS-II KW - tree species range expansion KW - tree species migration ER - TY - CHAP TI - The potential futures of Wisconsin forested landscapes AU - Scheller, R.M. AU - Mladenoff, D.J. T2 - The vanishing present: Ecological change in Wisconsin A2 - Waller, D.M. A2 - T.P. Rooney, AB - Abstract Chapters 5–7 showed that Wisconsin's forests have changed in many different ways, reflecting shifts in climate, variable soils, the migration of species following glaciation, natural disturbances, past and current logging, fragmentation from roads, and continuing shifts in human land use. Forest ecologists, historians, and sociologists use data from many sources to infer how Great Lakes states forests have changed and how these changes reflect broader geographic and historical contexts. In this era of global environmental change, can we use the past to anticipate and understand the future? Or will future changes be unique and unpredictable? The chapter grapples with these questions as it tries to imagine Wisconsin's forests 100 years from now, exploring the consequences of factors like population growth and climate change. PY - 2008/// DO - 10.7208/chicago/9780226871745.003.0031 PB - Chicago : University of Chicago Press ER - TY - JOUR TI - Simulation of forest change in the New Jersey Pine Barrens under current and pre-colonial conditions AU - Scheller, Robert M. AU - Van Tuyl, Steve AU - Clark, Kenneth AU - Hayden, Nicholas G. AU - Hom, John AU - Mladenoff, David J. T2 - FOREST ECOLOGY AND MANAGEMENT AB - Changes in land use patterns in and around forests, including rural development and road building, have occurred throughout the United States and are accelerating in many areas. As a result, there have been significant departures from ‘natural’ or pre-settlement disturbance regimes. Altered disturbance regimes can shift composition and dominance in tree species communities, potentially affecting ecosystem functioning. We examined the potential consequences of various forest management practices and forest fragmentation on tree community composition. Both forest management and fragmentation are changing as land use changes within the New Jersey Pine Barrens (NJPB). The NJPB has and is continuing to experience rapid rural development and urbanization that are altering the types, frequency, and intensity of forest management, and are increasing forest fragmentation. In the NJPB, the size and frequency of wildfires have declined and the use of prescribed fires is limited to a small portion of the landscape. In addition, the expansion of roads and decline in total forested area – two common measures of fragmentation – may impede the ability of tree species to colonize available habitat. To assess the consequences of fire management and fragmentation on fire regimes and forest communities, we simulated forest landscape change using LANDIS-II, a stochastic, spatially dynamic forest succession model that simulates the growth of tree species cohorts (defined by species and age), dispersal and colonization, and mortality. Simulated fires are sensitive to fuel loads and fuel load continuity. We constructed scenarios to mimic the pre-colonial contiguous landscape with an estimated pre-colonial fire regime; scenarios of the current day landscape with current and potential fire management; and scenarios designed to highlight the effects of fragmentation. Our simulations indicate that relative to the pre-colonial landscape and fire regime, the landscape is changing from a pine-dominated to an oak-dominated state. However, within areas where prescribed burning remains a viable management option, a doubling of the mean annual area that is managed with prescribed burns may substantially push the system back towards pre-colonial conditions, although oaks will continue to retain a higher than pre-colonial dominance. Our results also indicate that aside from a reduction in the potential fire sizes, fragmentation does not appear to substantially alter forest successional dynamics. In summary, our simulations estimate the departure from pre-colonial conditions and indicate the potential for a limited restoration of these conditions. DA - 2008/4/5/ PY - 2008/4/5/ DO - 10.1016/j.foreco.2007.11.025 VL - 255 IS - 5-6 SP - 1489-1500 SN - 0378-1127 KW - forest simulation model KW - fire management KW - forest fragmentation KW - wildland-urban interface KW - new jersey pine barrens KW - prescribed burning KW - natural range of variability ER - TY - JOUR TI - Susceptibility to Phytophthora ramorum in a key infectious host: landscape variation in host genotype, host phenotype, and environmental factors AU - Anacker, Brian L. AU - Rank, Nathan E. AU - Huberli, Daniel AU - Garbelotto, Matteo AU - Gordon, Sarah AU - Harnik, Tami AU - Whitkus, Richard AU - Meentemeyer, Ross T2 - NEW PHYTOLOGIST AB - • Sudden oak death is an emerging forest disease caused by the invasive pathogen Phytophthora ramorum. Genetic and environmental factors affecting susceptibility to P. ramorum in the key inoculum-producing host tree Umbellularia californica (bay laurel) were examined across a heterogeneous landscape in California, USA. • Laboratory susceptibility trials were conducted on detached leaves and assessed field disease levels for 97 host trees from 12 225-m2 plots. Genotype and phenotype characteristics were assessed for each tree. Effects of plot-level environmental conditions (understory microclimate, amount of solar radiation and topographic moisture potential) on disease expression were also evaluated. • Susceptibility varied significantly among U. californica trees, with a fivefold difference in leaf lesion size. Lesion size was positively related to leaf area, but not to other phenotypic traits or to field disease level. Genetic diversity was structured at three spatial scales, but primarily among individuals within plots. Lesion size was significantly related to amplified fragment length polymorphism (AFLP) markers, but local environment explained most variation in field disease level. • Thus, substantial genetic variation in susceptibility to P. ramorum occurs in its principal foliar host U. californica, but local environment mediates expression of susceptibility in nature. DA - 2008/// PY - 2008/// DO - 10.1111/j.1469-8137.2007.02297.x VL - 177 IS - 3 SP - 756-766 SN - 1469-8137 KW - amplified fragment length polymorphism (AFLP) KW - disease susceptibility KW - landscape epidemiology KW - oomycete KW - plant-pathogen interaction KW - sporangia KW - sudden oak death KW - Umbellularia californica ER - TY - JOUR TI - Multi-scale patterns of human activity and the incidence of an exotic forest pathogen AU - Cushman, J. Hall AU - Meentemeyer, Ross K. T2 - JOURNAL OF ECOLOGY AB - Summary Plant pathogens can have major impacts on diverse taxa and ecological systems world‐wide, and some of the most conspicuous of these are invasive non‐native species. Although many factors are known to influence the distribution and abundance of plant pathogens, the extent to which humans play a role is less well‐known but still critical for understanding the dynamics of invasive pathogens in natural systems. One invasive pathogen of great concern world‐wide is Phytophthora ramorum , which causes Sudden Oak Death, an emerging forest disease. Here, we examined the influence of humans and a range of environmental factors on the distribution of P. ramorum at three distinct spatial scales in northern and central California. At the local scale, P. ramorum more commonly occurred in soil on hiking trails used heavily by humans than in soil from adjacent areas off trails. These results support the hypothesis that humans dispersed the pathogen within already infected areas and into areas lacking local sources of inoculum. At the landscape scale, using a network of 202 randomly located plots across a 275 km 2 area, we found that forests on public land open to recreation exhibited higher prevalence of disease in a critical infectious host tree (bay laurel, Umbellularia californica ), than forests on private lands. Infection levels were also higher in plots surrounded by large amounts of forest with warm climatic conditions and greater potential soil moisture. Although prevalence of diseased canker hosts ( Quercus agrifolia, Q. kelloggii and Lithocarpus densiflora ) was positively associated with dominance of bay laurel and rainy season temperatures, it was not significantly related to public access, and we hypothesize that this occurred because our study area was in the early stages of infection. At the regional scale, the probability of disease occurrence at 165 sites distributed across the geographic range of P. ramorum in California increased significantly as human population density increased in the surrounding area. Chances of infection also increased significantly with precipitation and presence of bay laurel. Synthesis . Our results suggest that human activity – along with temperature, moisture and host composition – is associated with increased prevalence of an influential exotic forest pathogen. These results indicate that there may be conflicts between humans and disease, and that efforts to address this issue may require aggressive management of human activity. DA - 2008/7// PY - 2008/7// DO - 10.1111/j.1365-2745.2008.01376.x VL - 96 IS - 4 SP - 766-776 SN - 1365-2745 KW - disease incidence KW - exotic forest pathogen KW - foliar and canker hosts KW - human activity KW - Phytophthora ramorum KW - Sudden Oak Death ER - TY - JOUR TI - Influence of land-cover change on the spread of an invasive forest pathogen AU - Meentemeyer, Ross K. AU - Rank, Nathan E. AU - Anacker, Brian L. AU - Rizzo, David M. AU - Cushman, J. Hall T2 - ECOLOGICAL APPLICATIONS AB - Human-caused changes in land use and land cover have dramatically altered ecosystems worldwide and may facilitate the spread of infectious diseases. To address this issue, we examined the influence of land-cover changes between 1942 and 2000 on the establishment of an invasive pathogen, Phytophthora ramorum, which causes the forest disease known as Sudden Oak Death. We assessed effects of land-cover change, forest structure, and understory microclimate on measures of inoculum load and disease prevalence in 102 15 × 15 m plots within a 275-km2 region in northern California. Within a 150 m radius area around each plot, we mapped types of land cover (oak woodland, chaparral, grassland, vineyard, and development) in 1942 and 2000 using detailed aerial photos. During this 58-year period, oak woodlands significantly increased in area by 25%, while grassland and chaparral decreased by 34% and 51%, respectively. Analysis of covariance revealed that vegetation type in 1942 and woodland expansion were significant predictors of pathogen inoculum load in bay laurel (Umbellularia californica), the primary inoculum-producing host for P. ramorum in mixed evergreen forests. Path analysis showed that woodland expansion resulted in larger forests with higher densities of the primary host trees (U. californica, Quercus agrifolia, Q. kelloggii) and cooler understory temperatures. Together, the positive effects of woodland size and negative effects of understory temperature explained significant variation in inoculum load and disease prevalence in bay laurel; host stem density had additional positive effects on inoculum load. We conclude that enlargement of woodlands and closure of canopy gaps, likely due largely to years of fire suppression, facilitated establishment of P. ramorum by increasing the area occupied by inoculum-production foliar hosts and enhancing forest microclimate conditions. Epidemiological studies that incorporate land-use change are rare but may increase understanding of disease dynamics and improve our ability to manage invasive forest pathogens. DA - 2008/1// PY - 2008/1// DO - 10.1890/07-0232.1 VL - 18 IS - 1 SP - 159-171 SN - 1939-5582 KW - fire suppression KW - forest microclunate KW - landscape epidemiology KW - path analysis KW - Phytophthora ramorum KW - simultaneous autoregressive (SAR) modeling KW - Sudden Oak Death ER - TY - JOUR TI - Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California AU - Meentemeyer, R. K. AU - Rank, N. E. AU - Shoemaker, D. A. AU - Oneal, C. B. AU - Wickland, A. C. AU - Frangioso, K. M. AU - Rizzo, D. M. T2 - BIOLOGICAL INVASIONS DA - 2008/12// PY - 2008/12// DO - 10.1007/s10530-007-9199-5 VL - 10 IS - 8 SP - 1243-1255 SN - 1573-1464 KW - Big Sur KW - Emerging infectious disease KW - Forest disease KW - Invasive species KW - Landscape epidemiology KW - Phytophthora ramorum KW - Plant-pathogen KW - Tree mortality KW - Remote sensing ER - TY - JOUR TI - Early detection of emerging forest disease using dispersal estimation and ecological niche modeling AU - Meentemeyer, Ross K. AU - Anacker, Brian L. AU - Mark, Walter AU - Rizzo, David M. T2 - ECOLOGICAL APPLICATIONS AB - Ecological ApplicationsVolume 18, Issue 2 p. 377-390 Article EARLY DETECTION OF EMERGING FOREST DISEASE USING DISPERSAL ESTIMATION AND ECOLOGICAL NICHE MODELING Ross K. Meentemeyer, Corresponding Author Ross K. Meentemeyer [email protected] Department of Geography and Earth Sciences, University of North Carolina, 9201 University City Boulevard, Charlotte, North Carolina 28223 USA E-mail: [email protected]Search for more papers by this authorBrian L. Anacker, Brian L. Anacker Department of Geography and Earth Sciences, University of North Carolina, 9201 University City Boulevard, Charlotte, North Carolina 28223 USA Department of Environmental Science and Policy, University of California, 1 Shields Avenue, Davis, California 95616 USASearch for more papers by this authorWalter Mark, Walter Mark Department of Natural Resources Management, California Polytechnic State University, San Luis Obispo, California 93407 USASearch for more papers by this authorDavid M. Rizzo, David M. Rizzo Department of Plant Pathology, University of California, 1 Shields Avenue, Davis, California 95616 USASearch for more papers by this author Ross K. Meentemeyer, Corresponding Author Ross K. Meentemeyer [email protected] Department of Geography and Earth Sciences, University of North Carolina, 9201 University City Boulevard, Charlotte, North Carolina 28223 USA E-mail: [email protected]Search for more papers by this authorBrian L. Anacker, Brian L. Anacker Department of Geography and Earth Sciences, University of North Carolina, 9201 University City Boulevard, Charlotte, North Carolina 28223 USA Department of Environmental Science and Policy, University of California, 1 Shields Avenue, Davis, California 95616 USASearch for more papers by this authorWalter Mark, Walter Mark Department of Natural Resources Management, California Polytechnic State University, San Luis Obispo, California 93407 USASearch for more papers by this authorDavid M. Rizzo, David M. Rizzo Department of Plant Pathology, University of California, 1 Shields Avenue, Davis, California 95616 USASearch for more papers by this author First published: 01 March 2008 https://doi.org/10.1890/07-1150.1Citations: 89 Corresponding Editor: S. K. Collinge. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract Distinguishing the manner in which dispersal limitation and niche requirements control the spread of invasive pathogens is important for prediction and early detection of disease outbreaks. Here, we use niche modeling augmented by dispersal estimation to examine the degree to which local habitat conditions vs. force of infection predict invasion of Phytophthora ramorum, the causal agent of the emerging infectious tree disease sudden oak death. We sampled 890 field plots for the presence of P. ramorum over a three-year period (2003–2005) across a range of host and abiotic conditions with variable proximities to known infections in California, USA. We developed and validated generalized linear models of invasion probability to analyze the relative predictive power of 12 niche variables and a negative exponential dispersal kernel estimated by likelihood profiling. Models were developed incrementally each year (2003, 2003–2004, 2003–2005) to examine annual variability in model parameters and to create realistic scenarios for using models to predict future infections and to guide early-detection sampling. Overall, 78 new infections were observed up to 33.5 km from the nearest known site of infection, with slightly increasing rates of prevalence across time windows (2003, 6.5%; 2003–2004, 7.1%; 2003–2005, 9.6%). The pathogen was not detected in many field plots that contained susceptible host vegetation. The generalized linear modeling indicated that the probability of invasion is limited by both dispersal and niche constraints. Probability of invasion was positively related to precipitation and temperature in the wet season and the presence of the inoculum-producing foliar host Umbellularia californica and decreased exponentially with distance to inoculum sources. Models that incorporated niche and dispersal parameters best predicted the locations of new infections, with accuracies ranging from 0.86 to 0.90, suggesting that the modeling approach can be used to forecast locations of disease spread. Application of the combined niche plus dispersal models in a geographic information system predicted the presence of P. ramorum across ∼8228 km2 of California's 84 785 km2 (9.7%) of land area with susceptible host species. This research illustrates how probabilistic modeling can be used to analyze the relative roles of niche and dispersal limitation in controlling the distribution of invasive pathogens. Citing Literature Volume18, Issue22008Pages 377-390 RelatedInformation DA - 2008/3// PY - 2008/3// DO - 10.1890/07-1150.1 VL - 18 IS - 2 SP - 377-390 SN - 1939-5582 KW - dispersal kernel KW - early detection KW - ecological niche modeling KW - emerging infectious disease KW - invasive species KW - landscape epidemiology KW - Phytophthora ramorum KW - sudden oak death ER - TY - CONF TI - Research foundations of the VERP framework: A synopsis AU - Leung, Y.-F C2 - 2008/// C3 - Recreational Use and Resource Protection in National Parks: Conference Proceedings DA - 2008/// SP - i- PB - Hualien, Taiwan: National Dong Hwa University, Institute of Tourism and Recreation Management ER - TY - CHAP TI - Recreation ecology in sustainable tourism and ecotourism: a strengthening role AU - Leung, Yu-Fai AU - Marion, J. L. AU - Farrell, T. A. T2 - Tourism, Recreation and Sustainability: Linking Culture and the Environment, 2nd Ed. A2 - S. F. McCool, A2 - Neil, M. R. PY - 2008/// DO - 10.1079/9781845934705.0019 SP - 19–37 PB - Wallingford, UK: CABI Publishing ER - TY - RPRT TI - Annual Information Exchange -- Statistical Report of State Park Operations: 2006-07 AU - Leung, Y.-F AU - Siderelis, C. AU - Hoffbeck, D. A3 - Raleigh, NC: National Association of State Park Directors DA - 2008/// PY - 2008/// PB - Raleigh, NC: National Association of State Park Directors ER - TY - JOUR TI - Distribution of axial lava domes along a superfast overlapping spreading center, 27-32 degrees S on the East Pacific Rise AU - Bohnenstiehl, D. R. AU - Howell, J. K. AU - Hey, R. N. T2 - GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS AB - Deep‐towed DSL‐120 bathymetric data are used to investigate the pattern of lava dome formation along a superfast spreading portion of the southern East Pacific Rise (EPR), including the overlapping limbs of a giant (120 × 120 km) propagator near 29°S. Along the 670 km of the axis surveyed, 1172 small domes were identified using a closed contour algorithm. Their abundance, defined by spatial density, is well correlated with the along‐axis relief of the ridge crest. Where the western and eastern limbs plunge toward the overlap zone, densities are high (3–6 km −2 ); however, where the axial depth profile is shallow and flat, densities are comparably low (0.4 km −2 ). Volcanic domes within the low abundance areas are characterized by lower ratios of height to basal radius (0.15 versus 0.22), smaller maximum heights (18 versus 40 m), and a larger relative percentage of small versus large mounds. The zone of high dome abundance encompasses the overlapping limbs of the rift and extends more than 100 km to the north and south beyond the overlap zone. Domes form dominantly during low effusion rate, point‐source eruptions, which suggests that discontinuous melt lenses underlie the ridge axis proximal to the overlapper. Conversely, fissure‐fed sheet flows dominate along the more distal segments, implying the presence of a more continuous axial magma lens. Throughout the survey area, dome abundance increases systematically near second‐order segment boundaries. Within the high abundance zone, some third‐order offsets also correlate with increased dome production, but local peaks in abundance are not tied exclusively to higher‐order ridge offsets. Where dome abundance is low, domes are clustered tightly near second‐order offsets and there is no increase in dome abundance near third‐order segment boundaries. DA - 2008/12/12/ PY - 2008/12/12/ DO - 10.1029/2008gc002158 VL - 9 SP - SN - 1525-2027 KW - seamounts KW - lava domes KW - propagating rifts ER - TY - JOUR TI - SPATIAL-TEMPORAL MESOSCALE MODELING OF RAINFALL INTENSITY USING GAGE AND RADAR DATA AU - Fuentes, Montserrat AU - Reich, Brian AU - Lee, Gyuwon T2 - ANNALS OF APPLIED STATISTICS AB - Gridded estimated rainfall intensity values at very high spatial and temporal resolution levels are needed as main inputs for weather prediction models to obtain accurate precipitation forecasts, and to verify the performance of precipitation forecast models. These gridded rainfall fields are also the main driver for hydrological models that forecast flash floods, and they are essential for disaster prediction associated with heavy rain. Rainfall information can be obtained from rain gages that provide relatively accurate estimates of the actual rainfall values at point-referenced locations, but they do not characterize well enough the spatial and temporal structure of the rainfall fields. Doppler radar data offer better spatial and temporal coverage, but Doppler radar measures effective radar reflectivity (Ze) rather than rainfall rate (R). Thus, rainfall estimates from radar data suffer from various uncertainties due to their measuring principle and the conversion from Ze to R. We introduce a framework to combine radar reflectivity and gage data, by writing the different sources of rainfall information in terms of an underlying unobservable spatial temporal process with the true rainfall values. We use spatial logistic regression to model the probability of rain for both sources of data in terms of the latent true rainfall process. We characterize the different sources of bias and error in the gage and radar data and we estimate the true rainfall intensity with its posterior predictive distribution, conditioning on the observed data. Our model allows for nonstationary and asymmetry in the spatio-temporal dependency structure of the rainfall process, and allows the temporal evolution of the rainfall process to depend on the motions of rain fields, and the spatial correlation to depend on geographic features. We apply our methods to estimate rainfall intensity every 10 minutes, in a subdomain over South Korea with a spatial resolution of 1 km by 1 km. DA - 2008/12// PY - 2008/12// DO - 10.1214/08-AOAS166 VL - 2 IS - 4 SP - 1148-1169 SN - 1932-6157 KW - Conditionally autoregressive models KW - full symmetry KW - nonstationarity KW - rainfall modelling KW - spatial logistic regression KW - spatial-temporal models ER - TY - JOUR TI - The mesoscale characteristics of tropical oceanic precipitation during Kelvin and mixed Rossby-gravity wave events AU - Holder, Christopher T. AU - Yuter, Sandra E. AU - Sobel, Adam H. AU - Aiyyer, Anantha R. T2 - MONTHLY WEATHER REVIEW AB - Abstract Precipitation structures within Kelvin and mixed Rossby–gravity (MRG) wave troughs near Kwajalein Atoll during the 1999–2003 rainy seasons are analyzed using three-dimensional ground-based radar data and upper-air sounding data. Consistent with previous work, wave troughs are preferred locations for precipitation and typically yield 1.3 times more rain area compared to the overall rainy season climatology. Although the contiguous areas of cold cloudiness associated with tropical wave troughs are large and long lived, the underlying precipitation structure is most frequently small, isolated convection from mixed-phase clouds. This mismatch in instantaneous cold cloudiness area versus radar-observed precipitation area indicates differences in the rate and nature of evolution between the mesoscale anvil cloud and the underlying precipitating portion of the cloud. Mesoscale convective systems (MCSs) were identified during portions of 32 of the 39 wave trough events examined. Convective cells are frequently embedded within stratiform regions. Reflectivity holes or pores in contiguous radar echo have been frequently observed in other regions but are quantified for the first time in this study. Based on characteristics such as total size of precipitating area and occurrence of convective lines, MCSs within Kelvin troughs are slightly more organized than those occurring within MRG troughs. Similar to the west Pacific warm pool region, there is a well-defined separation between observed and unobserved stratiform area fraction and convective precipitation area, each as a function of total precipitation area. At precipitation area sizes near 40% of the radar domain, the maximum observed convective area changes from increasing to decreasing with increasing precipitation area. The maximum observed convective precipitation area occupied ∼20% of the radar domain. These characteristics suggest that the atmosphere in the west Pacific can sustain a limited area of updrafts capable of supporting precipitation growth by collision/coalescence and riming. DA - 2008/9// PY - 2008/9// DO - 10.1175/2008MWR2350.1 VL - 136 IS - 9 SP - 3446-3464 SN - 1520-0493 ER - TY - JOUR TI - Spatial and temporal variability of streambed hydraulic conductivity in West Bear Creek, North Carolina, USA AU - Genereux, David P. AU - Leahy, Scott AU - Mitasova, Helena AU - Kennedy, Casey D. AU - Corbett, D. Reide T2 - JOURNAL OF HYDROLOGY AB - The hydraulic conductivity (K) of the streambed is an important variable influencing water and solute exchange between streams and surrounding groundwater systems. However, there are few detailed data on spatial variability in streambed K and almost none on temporal variability. The spatial and temporal variability of streambed K in a North Carolina stream were investigated with 487 field measurements of K over a 1-year period. Measurements were made bimonthly from December 2005 to December 2006 at 46 measurement locations in a 262.5 m reach (the “large reach”). To give a more detailed picture of spatial variability, closely-spaced one-time measurements were made in two 62.5 m reaches (the “small reaches”, one investigated in July 2006 and the other in August 2006) that were part of the large reach. Arithmetic mean K for the large reach was ∼16 m/day (range was 0.01 to 66 m/day). Neither K nor lnK was normally distributed, and K distributions appeared somewhat bimodal. There was significant spatial variability over horizontal length scales of a few m. Perhaps the clearest feature within this variability was the generally higher K in the center of the channel. This feature may be an important control on water and chemical fluxes through the streambed (e.g., other measurements show generally higher water seepage velocity, but lower porewater nitrate concentration, in the center of the streambed). Grain size analysis of streambed cores showed that layers of elevated fines (silt + clay) content were less common in the center of the channel (overall, the streambed was about 94% sand). Results also suggest a modest but discernable difference in average streambed K upstream and downstream of a small beaver dam: K was about 23% lower upstream, when the dam was present during the first few months of the study. This upstream/downstream difference in K disappeared after the dam collapsed, perhaps in response to re-mobilization of fine sediments or leaf matter that had accumulated in quiet waters ponded on the upstream side of the dam. Temporal variability was significant and followed a variety of different patterns at the 46 measurement locations in the large reach. Temperature data show that variation in streambed and groundwater temperature was not an important cause of the observed temporal variability in K. Measurements of changes in the elevation of the streambed surface suggest erosion and deposition played an important role in causing the observed temporal variability in streambed K (of which the change described above following collapse of the beaver dam was a special case), though other potentially time-varying factors (e.g., gas content, bioturbation, or biofilms in the streambed) were not explicitly addressed and cannot be ruled out as contributors to the temporal variability in streambed K. Temporal variability in streambed K merits additional study as a potentially important control on temporal variability in the magnitudes and spatial patterns of water and solute fluxes between groundwater and surface water. From the data available it seems appropriate to view streambed K as a dynamic attribute, variable in both space and time. DA - 2008/9/5/ PY - 2008/9/5/ DO - 10.1016/j.jhydrol.2008.06.017 VL - 358 IS - 3-4 SP - 332-353 SN - 1879-2707 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-48849088675&partnerID=MN8TOARS KW - hydraulic conductivity KW - streambed KW - permeameter KW - semi-variogram KW - erosion KW - grain size ER - TY - JOUR TI - Multimodel ensembles of streamflow forecasts: Role of predictor state in developing optimal combinations AU - Devineni, Naresh AU - Sankarasubramanian, A. AU - Ghosh, Sujit T2 - Water Resources Research AB - A new approach for developing multimodel streamflow forecasts is presented. The methodology combines streamflow forecasts from individual models by evaluating their skill, represented by rank probability score (RPS), contingent on the predictor state. Using average RPS estimated over the chosen neighbors in the predictor state space, the methodology assigns higher weights for a model that has better predictability under similar predictor conditions. We assess the performance of the proposed algorithm by developing multimodel streamflow forecasts for Falls Lake Reservoir in the Neuse River Basin, North Carolina (NC), by combining streamflow forecasts developed from two low-dimensional statistical models that use sea-surface temperature conditions as underlying predictors. To evaluate the proposed scheme thoroughly, we consider a total of seven multimodels that include existing multimodel combination techniques such as combining based on long-term predictability of individual models and by simple pooling of ensembles. Detailed nonparametric hypothesis tests comparing the performance of seven multimodels with two individual models show that the reduced RPS from multimodel forecasts developed using the proposed algorithm is statistically significant from the RPSs of individual models and from the RPSs of existing multimodel techniques. The study also shows that adding climatological ensembles improves the multimodel performance resulting in reduced average RPS. Contingency analyses on categorical (tercile) forecasts show that the proposed multimodel combination technique reduces average Brier score and total number of false alarms, resulting in improved reliability of forecasts. However, adding multiple models with climatology also increases the number of missed targets (in comparison to individual models' forecasts) which primarily results from the reduction of increased resolution that is exhibited in the individual models' forecasts under various forecast probabilities. DA - 2008/9// PY - 2008/9// DO - 10.1029/2006wr005855 VL - 44 IS - 9 SP - J2 - Water Resour. Res. LA - en OP - SN - 0043-1397 UR - http://dx.doi.org/10.1029/2006WR005855 DB - Crossref ER - TY - JOUR TI - Modeling longitudinal spatial periodontal data: A spatially adaptive model with tools for specifying priors and checking fit AU - Reich, Brian J. AU - Hodges, James S. T2 - BIOMETRICS AB - Summary Attachment loss (AL), the distance down a tooth's root that is no longer attached to surrounding bone by periodontal ligament, is a common measure of periodontal disease. In this article, we develop a spatiotemporal model to monitor the progression of AL. Our model is an extension of the conditionally autoregressive (CAR) prior, which spatially smooths estimates toward their neighbors. However, because AL often exhibits a burst of large values in space and time, we develop a nonstationary spatiotemporal CAR model that allows the degree of spatial and temporal smoothing to vary in different regions of the mouth. To do this, we assign each AL measurement site its own set of variance parameters and spatially smooth the variances with spatial priors. We propose a heuristic to measure the complexity of the site‐specific variances, and use it to select priors that ensure parameters in the model are well identified. In data from a clinical trial, this model improves the fit compared to the usual dynamic CAR model for 90 of 99 patients' AL measurements. DA - 2008/9// PY - 2008/9// DO - 10.1111/j.1541-0420.2007.00956.x VL - 64 IS - 3 SP - 790-799 SN - 0006-341X KW - conditional autoregressive prior KW - disease monitoring KW - nonstationarity KW - periodontal data KW - spatiotemporal data ER - TY - JOUR TI - Frequency-magnitude distribution of microearthquakes beneath the 9 degrees 50 ' N region of the East Pacific Rise, October 2003 through April 2004 AU - Bohnenstiehl, D. R. AU - Waldhauser, F. AU - Tolstoy, M. T2 - GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS AB - Relocated hypocentral data from a 7‐month deployment (October 2003 to April 2004) of ocean bottom seismometers provide an opportunity to map microearthquake frequency‐magnitude distributions (FMDs) along the 9°49–52′N region on the East Pacific Rise. These analyses, which incorporate more than 9000 earthquakes, represent the first investigation of the 3‐D spatial and temporal patterns of FMDs along any mid‐ocean ridge spreading center. The data are described well by a Gutenberg‐Richter model, indicating a power law or fractal relationship between earthquake size and frequency. The scaling exponent, or b value, shows significant spatial variability, exceeding a value of 2.0 at the shallowest depths on axis and dropping below 1.0 away from the axial trough. This spatial pattern is consistent with an inverse relationship between b value and ambient stress conditions, with the lowest stress levels at shallow depths and relatively high stress levels (or low pore pressures) observed away from the axial zone. Intermediate b values are observed on‐axis above the ridge system's melt lens; however, within this region there also exists significant spatial variability. This indicates that stress conditions and/or structural heterogeneity may vary at subkilometer scales within the hydrothermal circulation cell. Although the observational period is characterized by increasing seismicity rates, building toward an eruptive episode in January 2006, the first‐order spatial pattern of b values is sustained, with no overall temporal trend. As a byproduct of this b value analysis, the detection capabilities of the array are assessed empirically. DA - 2008/10/21/ PY - 2008/10/21/ DO - 10.1029/2008gc002128 VL - 9 SP - SN - 1525-2027 KW - b values KW - microearthquakes KW - hydrothermal circulation KW - East Pacific Rise KW - mid-ocean ridge seismicity ER - TY - JOUR TI - Evaluation of atoxigenic isolates of Aspergillus flavus as potential biocontrol agents for aflatoxin in maize AU - Atehnkeng, J. AU - Ojiambo, P. S. AU - Ikotun, T. AU - Sikora, R. A. AU - Cotty, P. J. AU - Bandyopadhyay, R. T2 - FOOD ADDITIVES AND CONTAMINANTS PART A-CHEMISTRY ANALYSIS CONTROL EXPOSURE & RISK ASSESSMENT AB - Aflatoxin contamination resulting from maize infection by Aspergillus flavus is both an economic and a public health concern. Therefore, strategies for controlling aflatoxin contamination in maize are being investigated. The abilities of eleven naturally occurring atoxigenic isolates in Nigeria to reduce aflatoxin contamination in maize were evaluated in grain competition experiments and in field studies during the 2005 and 2006 growing seasons. Treatments consisted of inoculation of either grains in vials or ears at mid-silking stage in field plots, with the toxigenic isolate (La3228) or atoxigenic isolate alone and co-inoculation of each atoxigenic isolate and La3328. Aflatoxin B1 + B2 concentrations were significantly (p < 0.05) lower in the co-inoculation treatments compared with the treatment in which the aflatoxin-producing isolate La3228 was inoculated alone. Relative levels of aflatoxin B1 + B2 reduction ranged from 70.1% to 99.9%. Among the atoxigenics, two isolates from Lafia, La3279 and La3303, were most effective at reducing aflatoxin B1 + B2 concentrations in both laboratory and field trials. These two isolates have potential value as agents for the biocontrol of aflatoxin contamination in maize. Because these isolates are endemic to West Africa, they are both more likely than introduced isolates to be well adapted to West African environments and to meet regulatory concerns over their use throughout that region. DA - 2008/// PY - 2008/// DO - 10.1080/02652030802112635 VL - 25 IS - 10 SP - 1264-1271 SN - 1944-0057 UR - http://europepmc.org/abstract/med/18608502 KW - aflatoxin KW - corn KW - mycotoxin KW - competitive exclusion KW - West Africa ER - TY - JOUR TI - Diurnal characteristics of precipitation features over the tropical east Pacific: A comparison of the EPIC and TEPPS regions AU - Cifelli, R. AU - Nesbitt, S. W. AU - Rutledge, S. A. AU - Petersen, W. A. AU - Yuter, S. T2 - JOURNAL OF CLIMATE AB - Abstract This study examines the diurnal cycle of precipitation features in two regions of the tropical east Pacific where field campaigns [the East Pacific Investigation of Climate Processes in the Coupled Ocean–Atmosphere System (EPIC) and the Tropical Eastern Pacific Process Study (TEPPS)] were recently conducted. EPIC (10°N, 95°W) was undertaken in September 2001 and TEPPS (8°N, 125°W) was carried out in August 1997. Both studies employed C-band radar observations on board the NOAA ship Ronald H. Brown (RHB) and periodic upper-air sounding launches to observe conditions in the surrounding environment. Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and Geostationary Operational Environmental Satellite (GOES) IR data are used to place the RHB data in a climatological context and Tropical Atmosphere Ocean (TAO) buoy data are used to evaluate changes in boundary layer fluxes in context with the observed diurnal cycle of radar observations of precipitation features. Precipitation features are defined as contiguous regions of radar echo and are subdivided into mesoscale convective system (MCS) and sub-MCS categories. Results show that MCSs observed in EPIC and TEPPS have distinct diurnal signatures. Both regions show an increase in intensity starting in the afternoon hours, with the timing of maximum rain intensity preceding maxima in rain area and accumulation. In the TEPPS region, MCS rain rates peak in the evening and rain area and accumulation in the late night–early morning hours. In contrast, EPIC MCS rain rates peak in the late night–early morning, and rain area and accumulation are at a maximum near local sunrise. The EPIC observations are in agreement with previous satellite studies over the Americas, which show a phase lag response in the adjacent oceanic regions to afternoon–evening convection over the Central American landmass. Sub-MCS features in both regions have a broad peak extending through the evening to late night–early morning hours, similar to that for MCSs. During sub-MCS-only periods, the rainfall patterns of these features are closely linked to diurnal changes in SST and the resulting boundary layer flux variability. DA - 2008/8// PY - 2008/8// DO - 10.1175/2007JCLI2020.1 VL - 21 IS - 16 SP - 4068-4086 SN - 1520-0442 ER - TY - JOUR TI - Lack of correlation between chlorophyll a and cloud droplet effective radius in shallow marine clouds AU - Miller, Matthew A. AU - Yuter, Sandra E. T2 - GEOPHYSICAL RESEARCH LETTERS AB - The hypothesis that areas of high oceanic productivity affect the physical properties of shallow marine clouds via the production of secondary organic aerosols is evaluated using satellite data. The correlation between chlorophyll a concentrations, an indication of oceanic productivity, and low cloud droplet liquid phase effective radius ( R e ) is examined for several ocean regions and time periods. While a strong correlation between chlorophyll a and low R e can occur for specific periods in some locations, the correlation is not reproducible in other regions and time periods. The intermittent correlation between high concentrations of chlorophyll a and low R e is a coincidence and is not representative of a dominant, monotonic, causative relation between secondary organic aerosols and marine shallow cloud properties. DA - 2008/7/8/ PY - 2008/7/8/ DO - 10.1029/2008gl034354 VL - 35 IS - 13 SP - SN - 1944-8007 ER - TY - JOUR TI - Development of tuber blight (Phytophthora infestans) on potato cultivars based on in vitro assays and field evaluations AU - Nyankanga, Richard O. AU - Olanya, Ocen Modesto AU - Wien, Hans C. AU - El-Bedewy, Ramzy AU - Karinga, John AU - OJiambo, Peter S. T2 - HORTSCIENCE AB - Tuber blight may result from infection of wounded or unwounded potato tubers exposed to sporangia from foliar blight, soil, or blighted tubers. However, there are limited data on the prediction of tuber blight in field or storage environment based on in vitro assays. To assess this relationship, potato cultivars with foliar blight resistance (R-genes) and general resistance were evaluated for tuber blight incited by Phytophthora infestans (US-1) based on wound-induced and unwounded tuber inoculations. Surface lesion diameter, lesion depth, and frequency distribution of blighted tubers were assessed in in vitro assays and tuber blight incidence determined in field experiments. Significant differences ( P < 0.05) in lesion diameter and depth were recorded among cultivars. Surface lesion diameter, depth, and index ranged from 5 to 40, 2 to 16.3, and 15 to 656 mm, respectively, in wound-inoculated tubers. In nonwounded tuber assays, the incidence of blighted tubers ranged from 0% to 8.7% in both years. Tuber blight infection of potato cultivars varied between years in field studies. Although tuber infection differed among cultivars, the frequency of blighted tubers had a normal statistical distribution irrespective of R-genes, implying that foliar resistance may have limited effect on tuber blight occurrence based on in vitro experiments. Prediction of tuber blight based on inoculation assays can be effectively used to estimate and manage blight development in storage environments. DA - 2008/8// PY - 2008/8// DO - 10.21273/hortsci.43.5.1501 VL - 43 IS - 5 SP - 1501-1508 SN - 2327-9834 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-54249124087&partnerID=MN8TOARS KW - Phytophthora infestans KW - US-1 genotype KW - Solanum tuberosum KW - R-genes KW - tuber blight KW - tuber blight prediction ER - TY - JOUR TI - Evaluation of soybean germplasm for resistance to soybean rust (Phakopsora pachyrhizi) in Nigeria AU - Twizeyimana, M. AU - Ojiambo, P. S. AU - Ikotun, T. AU - Ladipo, J. L. AU - Hartman, G. L. AU - Bandyopadhyay, R. T2 - PLANT DISEASE AB - Soybean rust, caused by Phakopsora pachyrhizi, is one of the most important constraints to soybean production worldwide. The absence of high levels of host resistance to the pathogen has necessitated the continued search and identification of sources of resistance. In one set of experiments, 178 soybean breeding lines from the International Institute of Tropical Agriculture were rated for rust severity in the field in 2002 and 2003 at Ile-Ife, Yandev, and Ibadan, Nigeria. Thirty-six lines with disease severity ≤3 (based on a 0-to-5 scale) were selected for a second round of evaluation in 2004 at Ibadan. In the third round of evaluation under inoculated field conditions, 11 breeding lines with disease severity ≤2 were further evaluated for rust resistance at Ibadan in 2005 and 2006. The breeding lines TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F consistently had the lowest level of disease severity across years and locations. In another set of experiments, 101 accessions from the United States Department of Agriculture–Agricultural Research Service and National Agriculture Research Organization (Uganda) were evaluated in the first round in 2005 under inoculated conditions in the screenhouse; 12 accessions with disease severity ≤20% leaf area infected were selected for evaluation in the second round in 2005 and 2006 under inoculated field conditions at Ibadan. Highly significant differences (P < 0.0001) in disease severity were observed among the 101 accessions during this first round of rust evaluation. Significant (P < 0.0001) differences in rust severity and sporulation also were observed among the 12 selected accessions. Accessions PI 594538A, PI 417089A, and UG-5 had significantly (P < 0.05) lower disease severity than all other selected accessions in both years of evaluation, with rust severities ranging from 0.1 to 2.4%. These results indicate that some of the breeding lines (TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F) and accessions (PI 594538A, PI 417089A, and UG-5) would be useful sources of soybean rust resistance genes for incorporation into high-yielding and adapted cultivars. DA - 2008/6// PY - 2008/6// DO - 10.1094/PDIS-92-6-0947 VL - 92 IS - 6 SP - 947-952 SN - 1943-7692 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-46849092427&partnerID=MN8TOARS KW - disease resistance KW - stability analysis ER - TY - JOUR TI - Raindrop size distributions and rain characteristics in California coastal rainfall for periods with and without a radar bright band AU - Martner, Brooks E. AU - Yuter, Sandra E. AU - White, Allen B. AU - Matrosov, Sergey Y. AU - Kingsmill, David E. AU - Ralph, F. Martin T2 - JOURNAL OF HYDROMETEOROLOGY AB - Abstract Recent studies using vertically pointing S-band profiling radars showed that coastal winter storms in California and Oregon frequently do not display a melting-layer radar bright band and inferred that these nonbrightband (NBB) periods are characterized by raindrop size spectra that differ markedly from those of brightband (BB) periods. Two coastal sites in northern California were revisited in the winter of 2003/04 in this study, which extends the earlier work by augmenting the profiling radar observations with collocated raindrop disdrometers to measure drop size distributions (DSD) at the surface. The disdrometer observations are analyzed for more than 320 h of nonconvective rainfall. The new measurements confirm the earlier inferences that NBB rainfall periods are characterized by greater concentrations of small drops and smaller concentrations of large drops than BB periods. Compared with their BB counterparts, NBB periods had mean values that were 40% smaller for mean-volume diameter, 32% smaller for rain intensity, 87% larger for total drop concentration, and 81% larger (steeper) for slope of the exponential DSDs. The differences are statistically significant. Liquid water contents differ very little, however, for the two rain types. Disdrometer-based relations between radar reflectivity (Z) and rainfall intensity (R) at the site in the Coast Range Mountains were Z = 168R1.58 for BB periods and Z = 44R1.91 for NBB. The much lower coefficient, which is characteristic of NBB rainfall, is poorly represented by the Z–R equations most commonly applied to data from the operational network of Weather Surveillance Radar-1988 Doppler (WSR-88D) units, which underestimate rain accumulations by a factor of 2 or more when applied to nonconvective NBB situations. Based on the observed DSDs, it is also concluded that polarimetric scanning radars may have some limited ability to distinguish between regions of BB and NBB rainfall using differential reflectivity. However, differential-phase estimations of rain intensity are not useful for NBB rain, because the drops are too small and nearly spherical. On average, the profiler-measured echo tops were 3.2 km lower in NBB periods than during BB periods, and they extended only about 1 km above the 0°C altitude. The findings are consistent with the concept that precipitation processes during BB periods are dominated by ice processes in deep cloud layers associated with synoptic-scale forcing, whereas the more restrained growth of hydrometeors in NBB periods is primarily the result of orographically forced condensation and coalescence processes in much shallower clouds. DA - 2008/6// PY - 2008/6// DO - 10.1175/2007JHM924.1 VL - 9 IS - 3 SP - 408-425 SN - 1525-755X ER - TY - JOUR TI - Procedural urban modeling in practice AU - Watson, Benjamin AU - Mueller, Pascal AU - Wonka, Peter AU - Sexton, Chris AU - Veryovka, Oleg AU - Fuller, Andy T2 - IEEE COMPUTER GRAPHICS AND APPLICATIONS AB - Film and game studios can no longer meet audience demand for visual content by increasing production budgets. Instead they are turning to procedural modeling, particularly for modeling cities. The authors review procedural modeling, examine the CityEngine tool, and study the use of procedural urban modeling in Electronic Arts' Need for Speed games. DA - 2008/// PY - 2008/// DO - 10.1109/MCG.2008.58 VL - 28 IS - 3 SP - 18-26 SN - 1558-1756 ER - TY - JOUR TI - Procedural methods for urban modeling AU - Watson, Benjamin AU - Wonka, Peter T2 - IEEE COMPUTER GRAPHICS AND APPLICATIONS AB - Simulation of our man-made environment, especially cities, is becoming an increasingly important research problem in computer graphics. This special issue captures a good snapshot of work in this emerging area. DA - 2008/// PY - 2008/// DO - 10.1109/mcg.2008.57 VL - 28 IS - 3 SP - 16-17 SN - 0272-1716 ER - TY - JOUR TI - Effect of sampling density and design on estimation of streambed attributes AU - Kennedy, Casey D. AU - Genereux, David P. AU - Mitasova, Helena AU - Corbett, D. Reide AU - Leahy, Scott T2 - JOURNAL OF HYDROLOGY AB - Underlying questions that are central to field studies of the groundwater–surface water interaction are the extent of error in means and spatial distributions of streambed attributes such as groundwater seepage rate or solute flux, and the relation of this error to the number and location of point measurements. To investigate these questions, spatially intensive point measurements of five streambed attributes were made in two 63-m long stream reaches in the North Carolina Coastal Plain: hydraulic conductivity (K), hydraulic head gradient between groundwater and stream water (J), nitrate concentration in streambed groundwater (C), and groundwater seepage (v = KJ) and nitrate flux (f = vC) through the streambed. In all, 10 datasets (2 reaches, 5 attributes), each with 54 closely-spaced point values, were created (540-point values in all). For each dataset, subsets of 8- to 40-point values were selected from the 54 available to evaluate the effects of sampling density (the number of point values per reach, or per m2 of streambed) and sampling design (the relative number of point values from the right side, left side, and center of the channel) on the mean and the spatial field of the streambed attribute. Specifically, we evaluated the following as a function of sampling density and sampling design: (1) the likelihood of error in the reach-average value of each streambed attribute, (2) the average magnitude of error and distribution of error in the reach-average value of each attribute, (3) the magnitude of error in the prediction of point values of each attribute, and (4) the geometry of interpolated surfaces of two attributes (K and f). In all cases, “error” in a value or interpolated surface based on a subset of points was taken as a deviation from the corresponding result based on the full dataset of 54 points. The probability (p) that error did not occur increased with sampling density for each sampling design and attribute in both reaches, though the effect of “diminishing returns” was evident for sampling densities greater than ∼24 points per reach (roughly 0.05–0.06 points per m2 of streambed). Relative to sampling density, sampling design had little effect on values of p. Average error in streambed attributes was generally small (⩽10%) and less than the 95% confidence limits about the reach-average values of the attributes. The ability to estimate unknown point values by interpolation among other point values was poor using both 12- and 36-point subsets, though results suggest the 24 additional known point values (in going from 12 to 36) were helpful in one case in which there was some degree of autocorrelation between the additional known values and the values to be predicted in the interpolation. Visual inspection of 130 contour maps showed that those based on 36-point values were far more realistic in appearance than those based on 12-point values (where the standard for “realistic” appearance was the contour maps based on the full datasets of 54-point values). DA - 2008/6/20/ PY - 2008/6/20/ DO - 10.1016/j.jhydrol.2008.03.018 VL - 355 IS - 1-4 SP - 164-180 SN - 1879-2707 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-43949128733&partnerID=MN8TOARS KW - streambed KW - groundwater KW - sampling KW - error KW - nitrate KW - hydraulic conductivity ER - TY - JOUR TI - Per-pixel classification of high spatial resolution satellite imagery for urban land-cover mapping AU - Hester, David Barry AU - Cakir, Halil I. AU - Nelson, Stacy A. C. AU - Khorram, Siamak T2 - PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING AB - Commercial high spatial resolution satellite data now provide a synoptic and consistent source of digital imagery with detail comparable to that of aerial photography. In the work described here, per-pixel classification, image fusion, and GIS-based map refinement techniques were tailored to pan-sharpened 0.61 m QuickBird imagery to develop a six-category urban land-cover map with 89.3 percent overall accuracy ( �� 0.87). The study area was a rapidly developing 71.5 km 2 part of suburban Raleigh, North Carolina, U.S.A., within the Neuse River basin. “Edge pixels” were a source of classification error as was spectral overlap between bare soil and impervious surfaces and among vegetated cover types. Shadows were not a significant source of classification error. These findings demonstrate that conventional spectral-based classification methods can be used to generate highly accurate maps of urban landscapes using high spatial resolution imagery. DA - 2008/4// PY - 2008/4// DO - 10.14358/PERS.74.4.463 VL - 74 IS - 4 SP - 463-471 SN - 2374-8079 ER - TY - JOUR TI - Simultaneous regression shrinkage, variable selection, and supervised clustering of predictors with OSCAR AU - Bondell, Howard D. AU - Reich, Brian J. T2 - BIOMETRICS AB - Summary Variable selection can be challenging, particularly in situations with a large number of predictors with possibly high correlations, such as gene expression data. In this article, a new method called the OSCAR (octagonal shrinkage and clustering algorithm for regression) is proposed to simultaneously select variables while grouping them into predictive clusters. In addition to improving prediction accuracy and interpretation, these resulting groups can then be investigated further to discover what contributes to the group having a similar behavior. The technique is based on penalized least squares with a geometrically intuitive penalty function that shrinks some coefficients to exactly zero. Additionally, this penalty yields exact equality of some coefficients, encouraging correlated predictors that have a similar effect on the response to form predictive clusters represented by a single coefficient. The proposed procedure is shown to compare favorably to the existing shrinkage and variable selection techniques in terms of both prediction error and model complexity, while yielding the additional grouping information. DA - 2008/3// PY - 2008/3// DO - 10.1111/j.1541-0420.2007.00843.x VL - 64 IS - 1 SP - 115-123 SN - 0006-341X KW - correlation KW - penalization KW - predictive group KW - regression KW - shrinkage KW - supervised clustering KW - variable selection ER - TY - JOUR TI - Novel sources of resistance to Fusarium stalk rot of maize in tropical Africa AU - Afolabi, C. G. AU - Ojiambo, P. S. AU - Ekpo, E. J. A. AU - Menkir, A. AU - Bandyopadhyay, R. T2 - PLANT DISEASE AB - Fusarium stalk rot is one of the most widespread and destructive diseases of maize, and deployment of resistant genotypes is one of the most effective strategies for controlling the disease. Fifty inbred lines and four checks from the breeding program of the International Institute of Tropical Agriculture were evaluated in field trials at Ikenne and Ibadan, Nigeria in 2003 and 2004 to identify new sources of resistance to stalk rot caused by Fusarium verticillioides. Evaluations were conducted under artificial inoculation and natural infection at Ibadan and Ikenne, respectively. Disease severity was recorded using a severity scale (SS) and direct estimation of stalk discoloration (SD). The two methods of disease assessment were compared and combined to classify genotypes into resistance groups using results from rank-sum analysis. In 2003, disease severity ranged from SS = 1 to 5 and SD = 1.3 to 33.8% at both locations. Both SS and SD were significantly (P < 0.01) higher in 2003 than in 2004 at the two locations. In both years, inbred lines significantly differed in SS (P < 0.02) and SD (P < 0.04) at Ibadan. Similarly, inbred lines significantly differed in SS (P < 0.04) and SD (P < 0.04) when genotypes were evaluated at Ikenne. Disease assessments based on SS and SD were significantly correlated (0.68 < r < 0.95, P < 0.01) in both years. Based on the results from rank-sum analysis, inbred lines were separated into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible, and highly susceptible groups. At Ibadan, 6 (11.1%) and 8 (14.8%) were identified as highly resistant and resistant, respectively, whereas 11 (20.4%) were identified as resistant at Ikenne. Inbred lines 02C14609, 02C14643, 02C14654, and 02C14678 were consistently classified as either highly resistant or resistant to stalk rot across locations and years while the check genotypes were classified either as susceptible or moderately susceptible to stalk rot. These four inbred lines identified to have high levels of disease resistance may be used for breeding maize with resistance to Fusarium stalk rot. DA - 2008/5// PY - 2008/5// DO - 10.1094/PDIS-92-5-0772 VL - 92 IS - 5 SP - 772-780 SN - 1943-7692 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-44349103720&partnerID=MN8TOARS ER - TY - JOUR TI - High-resolution observations and model simulations of the life cycle of an intense mesoscale snowband over the northeastern United States AU - Novak, David R. AU - Colle, Brian A. AU - Yuter, Sandra E. T2 - MONTHLY WEATHER REVIEW AB - Abstract This paper investigates the structural and dynamical evolution of an intense mesoscale snowband occurring 25–26 December 2002 over the northeastern United States. Dual-Doppler, wind profiler, aircraft, and water vapor observations in concert with the fifth-generation Pennsylvania State University–NCAR Mesoscale Model run at 4-km grid spacing are used to highlight evolutionary aspects of a snowband unresolved by previous studies. The high-resolution observations and model simulations show that band formation was coincident with a sharpening of a midlevel trough and associated increase in frontogenesis in an environment of conditional and inertial instability. Band maturity was marked by increasing conditional stability and a threefold increase in frontogenetical forcing. Band dissipation occurred as the midlevel trough and associated frontogenetical forcing weakened, while the conditional stability continued to increase. The effect of changing ascent is shown to dominate over changing moisture in explaining band dissipation in this case. Unconventional aspects of band structure and dynamics revealed by the high-resolution data are discussed, including the location of the band relative to the frontogenesis maximum, increasing stability during the band-formation process, and the presence of inertial instability. The model realistically predicted the band evolution; however, maximum precipitation was underforecast within the banded region by ∼30% at 4-km grid spacing, and the axis of heaviest precipitation was displaced ∼50 km to the southeast of the observed location. Higher horizontal model resolution is shown to contribute toward improved QPF in this case; however, it appears more dramatic improvement may be gained by better simulating the frontogenesis, stability, and moisture evolution. DA - 2008/4// PY - 2008/4// DO - 10.1175/2007MWR2233.1 VL - 136 IS - 4 SP - 1433-1456 SN - 1520-0493 ER - TY - JOUR TI - Seed odor mediates an obligate ant-plant mutualism in Amazonian rainforests AU - Youngsteadt, Elsa AU - Nojima, Satoshi AU - Haeberlein, Christopher AU - Schulz, Stefan AU - Schal, Coby T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - Seed dispersal mutualisms are essential for the survival of diverse plant species and communities worldwide. Among invertebrates, only ants have a major role in seed dispersal, and thousands of plant species produce seeds specialized for ant dispersal in "diffuse" multispecies interactions. An outstanding but poorly understood ant-seed mutualism occurs in the Amazonian rainforest, where arboreal ants collect seeds of several epiphyte species and cultivate them in nutrient-rich nests, forming abundant and conspicuous hanging gardens known as ant-gardens (AGs). AG ants and plants are dominant members of lowland Amazonian ecosystems, and their interaction is both specific and obligate, but the means by which ants locate, recognize, and accept their mutualist seeds while rejecting other seeds is unknown. Here we address the chemical and behavioral basis of the AG interaction. We show that workers of the AG ant Camponotus femoratus are attracted to odorants emanating from seeds of the AG plant Peperomia macrostachya, and that chemical cues also elicit seed-carrying behavior. We identify five compounds from P. macrostachya seeds that, as a blend, attract C. femoratus workers. This report of attractive odorants from ant-dispersed seeds illustrates the intimacy and complexity of the AG mutualism and begins to illuminate the chemical basis of this important and enigmatic interaction. DA - 2008/3/25/ PY - 2008/3/25/ DO - 10.1073/pnas.0708643105 VL - 105 IS - 12 SP - 4571-4575 SN - 0027-8424 ER - TY - JOUR TI - Role of retrospective forecasts of GCMs forced with persisted SST anomalies in operational streamflow forecasts development AU - Sankarasubramanian, A. AU - Lall, Upmanu AU - Espinueva, Susan T2 - JOURNAL OF HYDROMETEOROLOGY AB - Abstract Seasonal streamflow forecasts contingent on climate information are essential for water resources planning and management as well as for setting up contingency measures during extreme years. In this study, operational streamflow forecasts are developed for a reservoir system in the Philippines using ECHAM4.5 precipitation forecasts (EPF) obtained using persisted sea surface temperature (SST) scenarios. Diagnostic analyses on SST conditions show that the tropical SSTs influence the streamflow during extreme years, whereas the local SSTs (0°–25°N, 115°–130°E) account for streamflow variability during normal years. Given that the EPF, local, and tropical SST conditions are spatially correlated, principal components regression (PCR) is employed to downscale the GCM-predicted precipitation fields and SST anomalies to monthly streamflow forecasts and to update them every month within the season using the updated EPF and SST conditions. These updated forecasts improve the prediction of monthly streamflows within the season in comparison to the skill of the monthly streamflow forecasts issued at the beginning of the season. It is also shown that the streamflow forecasting model developed using EPF under persisted SST conditions performs well upon employing EPF obtained under predicted SSTs as predictor. This has potential implications in the development of operational streamflow forecasts and statistical downscaling, which requires adequate years of retrospective GCM forecasts for recalibration. Finally, the study also shows that predicting the seasonal streamflow using the monthly precipitation forecasts reproduces the observed seasonal total better than the conventional approach of using seasonal precipitation forecasts to predict the seasonal streamflow. DA - 2008/4// PY - 2008/4// DO - 10.1175/2007JHM842.1 VL - 9 IS - 2 SP - 212-227 SN - 1525-7541 ER - TY - JOUR TI - Identitication of the variance components in the general two-variance linear model AU - Reich, Brian J. AU - Hodges, James S. T2 - JOURNAL OF STATISTICAL PLANNING AND INFERENCE AB - Bayesian analyses frequently employ two-stage hierarchical models involving two-variance parameters: one controlling measurement error and the other controlling the degree of smoothing implied by the model's higher level. These analyses can be hampered by poorly identified variances which may lead to difficulty in computing and in choosing reference priors for these parameters. In this paper, we introduce the class of two-variance hierarchical linear models and characterize the aspects of these models that lead to well-identified or poorly identified variances. These ideas are illustrated with a spatial analysis of a periodontal data set and examined in some generality for specific two-variance models including the conditionally autoregressive (CAR) and one-way random effect models. We also connect this theory with other constrained regression methods and suggest a diagnostic that can be used to search for missing spatially varying fixed effects in the CAR model. DA - 2008/7/1/ PY - 2008/7/1/ DO - 10.1016/j.jspi.2007.05.046 VL - 138 IS - 6 SP - 1592-1604 SN - 0378-3758 KW - conditional autoregressive prior KW - hierarchical models KW - identification KW - mixed linear model KW - variance components ER - TY - JOUR TI - Pixel level fusion of panchromatic and multispectral images based on correspondence analysis AU - Cakir, Halil I. AU - Khorram, Siamak T2 - PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING AB - A pixel level data fusion approach based on correspondence analysis (CA) is introduced for high spatial and spectral resolution satellite data. Principal component analysis (PCA) is a well-known multivariate data analysis and fusion technique in the remote sensing community. Related to PCA but a more recent multivariate technique, correspondence analysis, is applied to fuse panchromatic data with multispectral data in order to improve the quality of the final fused image. In the CA-based fusion approach, fusion takes place in the last component as opposed to the first component of the PCA-based approach. This new approach is then quantitatively compared to the PCA fusion approach using Landsat ETM� , QuickBird, and two Ikonos (with and without dynamic range adjustment) test imagery. The new approach provided an excellent spectral accuracy when synthesizing images from multispectral and high spatial resolution panchromatic imagery. DA - 2008/2// PY - 2008/2// DO - 10.14358/PERS.74.2.183 VL - 74 IS - 2 SP - 183-192 SN - 2374-8079 ER -