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2D lattice neutral models in ecology are studied using general-purpose computing on graphic processing units (GPGPU). Processing times of GPGPU and CPU simulations are compared for various system sizes and it is found out that the larger the system size, the faster the GPGPU version, and the efficiency of GPGPU is maximally 263 times higher. Ecological significance of the GPGPU simulations and the lattice neutral model is also reported.
The energy-systems language method of modelling and simulation, because of its energy constrained rules, is a means for transferring homologous concepts between levels of the hierarchies of nature. Mathematics of self-organization may justify emulation as the simulation of systems overview without details. Here, these methods are applied to the new fields of ecological economics and ecological engineering . Since the vitality of national economics depends on the symbiotic coupling of environmental resources and human economic behavior, the energy language is adapted to develop overview models of nations relevant to public policies. An overview model of a developing nation is given as an example with simulations for alternative policies. Maximum economic vitality was obtained with trade for external resources, but ultimate economic carrying capacity and standard of living was determined by indigenous resources, optimum utilization and absence of foreign debt.
The interrelationship of society and environment is addressed here through the study of a remote fishing village of 750 people. An interdisciplinary study evaluated demographic, economic, and social aspects of the community, and simulationmodeling was used to integrate these societal characteristics with environmental factors. The population of the village had grown gradually until the 1960's, when a decline began. Out-migration correlated with declining fish harvests and with increased communications with urban centers. Fishing had provided the greatest economic opportunity, followed by logging. A survey was conducted to investigate the costs and revenues of village fishermen. Diversification characterized the local fleet, and analysis showed that rates of return on investment in the current year were equal between vessel types. The variable levels and rate parameters of the demographic, economic, and social components of the model were specified through static and time series data. Sensitivity analysis to assess the effects of uncertainty, and validation tests against known historical changes were also conducted. Forecast scenarios identified the development options under several levels of fish abundance and investment. The weight given to ecological versus economic resource management registered disproportionate effects due to the interaction between investment and migration rates and resource stochasticity. This finding argues against a “golden mean” rule for evaluating policy trade-offs and argues for the importance of using a dynamic, socio-ecological perspective in designing development policies for rural communities.
This paper develops an integrated strategy to model the urban development and ecological dynamics in the Central Puget Sound Region. This effort is part of the Puget Sound Regional Integrated Synthesis model (PRISM) - an interdisciplinary initiative at the University of Washington aiming to develop a dynamic and integrated understanding of the environmental and human systems in the Puget Sound.
A mathematical model for computer simulation of aquatic ecosystems was developed and adapted to lake and estuarial systems. The model is capable of simulating the annual cycle of ecologic successions involving algae, bacteria, zooplankton, fish and benthi...
KIAMBRAM, a detailed simulationmodel for ecological succession in an Australian subtropical humid rainforest is documented in respect to model structure. Model parameters for 125 rainforest tree species are provided. A listing of the KIAMBRAM model and a sample of output from the model is included.
Computer simulation has become important in ecologicalmodeling, but there have been few assessments on how complex simulation\\u000a models differ from more traditional analytic models. In Part I of this paper, I review the challenges faced in complex ecological\\u000a modeling and how models have been used to gain theoretical purchase for understanding natural systems. I compare the use of\\u000a traditional
The main objectives of this project are a) to develop a general methodology for conducting sensitivity and uncertainty analysis and building error budgets in simulationmodeling over space and time; and b) to apply that methodology to the assessment of soil erosion through the RU...
Risk assessment for pesticides in the aquatic environment relies on a comparison between estimated exposure concentrations in surface water bodies and endpoints from a series of effect tests. Many field- and catchment-scale models have been developed, ranging from simple empirical models to comprehensive, physically-based, distributed models that require complex parameterisation, often through inverse modelling methods. Routine use of catchment models for assessment and management of pesticides requires a tool that is comprehensive in being able to address all major routes of entry of pesticides into surface water and that has reasonable parameter requirements. Current models either focus primarily on transport of pesticides in surface runoff or are restricted in application because they require calibration against data from detailed monitoring programmes. SPIDER (Simulating Pesticides In Ditches to assess Ecological Risk) was developed to address the gap in models available to simulate pesticide exposure within networks of small surface water bodies (ditches and streams) in support of ecological risk assessment for pesticides. SPIDER is a locally distributed, capacitance-based model that accounts for pesticide entry into surface water bodies via spray drift, surface runoff, interlayer flow and drainflow and that can be used for small agricultural catchments. This paper provides a detailed description of the model. PMID:18275984
Computer models are increasingly being used by forest ecologists and managers to simulate long-term forest landscape change.\\u000a We review models of forest landscape change from an ecological rather than methodological perspective. We developed a classification\\u000a based on the representation of three ecological criteria: spatial interactions, tree species community dynamics, and ecosystem\\u000a processes. Spatial interactions are processes that spread across a
A key component of this capability package is the Ecological Dynamics Simulation (EDYS) model. The model provides the capability to predict responses of training lands to both military and non-military stressors and facilitates linking the cost of training and testing land mainte...
Summary Although advanced land surface schemes have been developed in the past decade, many biosphere models still use the simple\\u000a bucket model, partly due to its efficiency when it is coupled with an CGCM model. In this paper, we use a sophisticated land\\u000a surface model, the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS), including an explicit vegetation
Ecological land is like the “liver” of a city and is very useful to public health. Ecological land change is a spatially dynamic non-linear process under the interaction between natural and anthropogenic factors at different scales. In this study, by setting up natural development scenario, object orientation scenario and ecosystem priority scenario, a Cellular Automation (CA) model has been established to simulate the evolution pattern of ecological land in Beijing in the year 2020. Under the natural development scenario, most of ecological land will be replaced by construction land and crop land. But under the scenarios of object orientation and ecosystem priority, the ecological land area will increase, especially under the scenario of ecosystem priority. When considering the factors such as total area of ecological land, loss of key ecological land and spatial patterns of land use, the scenarios from priority to inferiority are ecosystem priority, object orientation and natural development, so future land management policies in Beijing should be focused on conversion of cropland to forest, wetland protection and prohibition of exploitation of natural protection zones, water source areas and forest parks to maintain the safety of the regional ecosystem.
Ecological land is like the "liver" of a city and is very useful to public health. Ecological land change is a spatially dynamic non-linear process under the interaction between natural and anthropogenic factors at different scales. In this study, by setting up natural development scenario, object orientation scenario and ecosystem priority scenario, a Cellular Automation (CA) model has been established to simulate the evolution pattern of ecological land in Beijing in the year 2020. Under the natural development scenario, most of ecological land will be replaced by construction land and crop land. But under the scenarios of object orientation and ecosystem priority, the ecological land area will increase, especially under the scenario of ecosystem priority. When considering the factors such as total area of ecological land, loss of key ecological land and spatial patterns of land use, the scenarios from priority to inferiority are ecosystem priority, object orientation and natural development, so future land management policies in Beijing should be focused on conversion of cropland to forest, wetland protection and prohibition of exploitation of natural protection zones, water source areas and forest parks to maintain the safety of the regional ecosystem. PMID:23066410
SPIDER (simulating pesticides in ditches to assess ecological risk) is a locally distributed, capacitance-based model that accounts for pesticide entry into surface water bodies via spray drift, surface runoff, interlayer flow and drainage. SPIDER was developed for application to small agricultural catchments. Transport of pesticide from site of application to surface water via subsurface field drains is one of the major routes of entry to surface water. Several pesticide fate models describe transfer of pesticide via drainflow, notably MACRO which has been evaluated against field data in several studies. The capacity of SPIDER to simulate drainflow and pesticide concentration in drain water was evaluated against two datasets that had been used previously to evaluate MACRO independently of this study: a plot experiment at Cockle Park and a field experiment at Maidwell, both located in the UK. In both circumstances, SPIDER was able to reproduce drain hydrographs relatively well with no or limited calibration. At Cockle Park, simulated and observed drainflow over the season were 240 and 278 mm, respectively with a Nash and Sutcliffe model efficiency (NSME) coefficient of 0.32 whilst at Maidwell they were 259 and 296 mm, respectively with a NSME coefficient of 0.55. Prediction of maximum isoproturon concentration at Cockle Park by SPIDER and MACRO were 5.3 and 13.1 microg L(- 1) respectively compared to the 3.8 microg L(- 1) measured in the field, whilst pesticide load to drains over the season were 0.22 and 1.53 g, respectively, compared to an observed load of 0.35 g. Maximum sulfosulfuron concentration at Maidwell were 2.3, 3.9 and 5.4 microg L(- 1) for observed and as simulated by SPIDER and MACRO, respectively and pesticide loading to drains of the season was 0.77, 5.61, 4.77 g, respectively. Results from the sensitivity analysis showed that the sensitivity of SPIDER compared favourably to that of several other capacity models but was more sensitive than MACRO to variations in input parameters. SPIDER is currently being tested at the catchment scale. PMID:18280538
Interest in the integrated restoration of managed river corridors has arisen in response to falling levels of riparian and floodplain biodiversity due to flood control works including channalization and flow regulation by headwater impoundments. This decline is in part, a direct response to the impact of engineering works on the geomorphological dynamics of rivers and in particular, upon rates of channel migration. Channel instability, through the processes of bank erosion, avulsion and cutoff, and within and overbank sedimentation, continuously renews the floodplain creating virgin territory for plant colonization. The varying age of alluvial surfaces, in combination with differences in topography and sediment calibre influence plant succession pathways and gives rise to a mosaic of floodplain plant communities. This geomorphological influence underpins the `intermediate disturbance hypothesis' which suggests a non-linear relationship between floodplain turnover rates and biodiversity, which is low in both highly stable and unstable rivers regimes. In the former case, diversity is limited as stable regimes promote succession towards relatively uniform stands of floodplain forest while the in the later case, extreme instability results in the sole dominance of early coloniser species. By contrast, diversity is maximized for intermediate levels of disturbance, which result in a range of habitats at varying positions along successional pathways. While conceptually satisfying, calibration and validation of this perceptual model is confounded by the differing local conditions and environmental history of individual rivers, which complicates simple empirical inter-comparisons. Prescription of the appropriate levels of disturbance necessary to optimise habitat and biological diversity therefore remains unclear and difficult to translate into practical frameworks for river management. This paper presents an alternative approach to investigate this interdependence through the development of a numerical model which captures the primary geomorphological and ecological dynamics of river systems at appropriate levels of complexity tuned to reach and decadal space and time scales. Here a prototype model is presented for braided rivers, in which a simplified flow routing procedure is used to drive predictions of sediment transport and sorting based on a cellular spatial discretization, a force-balance entrainment model and a step-length advection and grain sorting procedure. This sub-model provides the topographic and sedimentological boundary conditions for a stochastic plant succession model which simulates colonization and community development on the evolving braidplain. The model is parameterised and validated against distributed datasets from the braided River Feshie, Scotland. A Monte-Carlo based sensitivity analysis is used to explore the one-way interaction between channel migration and habitat development, with an emphasis placed on the structure of the evolving timeseries of reach-scale biodiversity indicators. Importantly however, the framework also permits full coupling of this interrelationship by modelling the influence of vegetation on bank stability so that feedback can occur to affect channel migration and floodplain turnover. Such feedback is critical in understanding the autogenic switching between channel planform types (meandering and braiding) and a new computational framework for simulating this behaviour is presented.
Ecologicalsimulationmodels are widely used in ecology to help understand and predict the behavior of ecosystems. Many of the questions now being asked in ecology, such as the effects of climate change on ecosystems or the risks to ecosystems from contaminants, require extrapolation in both space and time and often require the collaboration of scientists from several fields of
This study examines the utilization and management of natural forest lands to meet growing wood-energy demands. An application of a forest simulationmodel is described for assessing energy returns and long-term ecological impacts of wood-energy harvesting under four general silvicultural practices. Results indicate that moderate energy yields could be expected from mild cutting operations which would significantly effect neither the commercial timber market nor the composition, structure, or diversity of these forests. Forest models can provide an effective tool for determining optimal management strategies that maximize energy returns, minimize environmental detriment, and complement existing land-use plans.
BACKGROUND: Malaria is one of the oldest and deadliest infectious diseases in humans. Many mathematical models of malaria have been developed during the past century, and applied to potential interventions. However, malaria remains uncontrolled and is increasing in many areas, as are vector and parasite resistance to insecticides and drugs. METHODS: This study presents a simulationmodel of African malaria
Jean-Marc O Depinay; Charles M Mbogo; Gerry Killeen; Bart Knols; John Beier; John Carlson; Jonathan Dushoff; Peter Billingsley; Henry Mwambi; John Githure; Abdoulaye M Toure; F Ellis McKenzie
Background Malaria is one of the oldest and deadliest infectious diseases in humans. Many mathematical models of malaria have been developed during the past century, and applied to potential interventions. However, malaria remains uncontrolled and is increasing in many areas, as are vector and parasite resistance to insecticides and drugs. Methods This study presents a simulationmodel of African malaria vectors. This individual-based model incorporates current knowledge of the mechanisms underlying Anopheles population dynamics and their relations to the environment. One of its main strengths is that it is based on both biological and environmental variables. Results The model made it possible to structure existing knowledge, assembled in a comprehensive review of the literature, and also pointed out important aspects of basic Anopheles biology about which knowledge is lacking. One simulation showed several patterns similar to those seen in the field, and made it possible to examine different analyses and hypotheses for these patterns; sensitivity analyses on temperature, moisture, predation and preliminary investigations of nutrient competition were also conducted. Conclusions Although based on some mathematical formulae and parameters, this new tool has been developed in order to be as explicit as possible, transparent in use, close to reality and amenable to direct use by field workers. It allows a better understanding of the mechanisms underlying Anopheles population dynamics in general and also a better understanding of the dynamics in specific local geographic environments. It points out many important areas for new investigations that will be critical to effective, efficient, sustainable interventions.
Depinay, Jean-Marc O; Mbogo, Charles M; Killeen, Gerry; Knols, Bart; Beier, John; Carlson, John; Dushoff, Jonathan; Billingsley, Peter; Mwambi, Henry; Githure, John; Toure, Abdoulaye M; Ellis McKenzie, F
Soils are important components of ecosystem and their functioning is of great importance for human well-being. Describing, understanding, foreseeing, and controlling biological activities and functions in soil in the context of global change are major objectives for scientists. Modelling soil bioturbation by soil engineers is of great importance although it is faced with the difficulty to describe the soil physical
N. Marilleau; C. Cambier; Alexis Drogoul; J.-L. Chotte; Edith Perrier; E. Blanchart
An ecological process model of vegetation dynamics mechanistically simulates long-term stand dynamics on coniferous landscapes of the Northern Rocky Mountains. This model is used to investigate and evaluate cumulative effects of various fire regimes, including prescribed burning and fire exclusion, on the vegetation and fuel complex of a simulation landscape composed of many stands. Detailed documentation of the model FIRE-BGC (a FIRE BioGeoChemical succession model) with complete discussion of all model parameters is followed with results of an application of the FIRE-BGC to a whitebark pine landscape in the Bob Marshall Wilderness Complex. Simulation results of several management scenarios are contrasted to predict the fate of whitebark pine over 200 years. Model testing reveals predictions within 10 to 30 percent of observed values.
|Presents a method which organizes concepts and relates different phenomena to a single model of ecology. Describes how this model is used to explain the overall significance of biological and ecological cycles and its usefulness in helping students to understand the various dangers to and remedies available for an ecosystem. (CS)|
The genre ecology framework is an analytical framework for studying how people use multiple artifacts - such as documentation, interfaces, and annotations - to mediate their work activities. Unlike other analytical frameworks, the genre ecology framework has been developed particularly for technical communication research, particularly in its emphasis on interpretation, contingency, and stability. Although this framework shows much promise, it
The ecological literature reveals considerable confusion about the meaning of validation in the context of simulationmodels. The confusion arises as much from semantic and philosophical considerations as from the selection of validation procedures. Validation is not a procedure for testing scientific theory or for certifying the ‘truth’ of current scientific understanding, nor is it a required activity of every
Definitions of model realism and model validation are developed. Ecological and mathematical arguments are then presented to show that model equations which explicitly treat ecosystem processes can be systematically improved such that greater realism is attained and the condition of validity is approached. Several examples are presented.
An ecologicalmodel is a mathematical statement of the rules governing ecosystem changes. Traditional models based on system dynamics approach provide a useful way to represent and comprehend changing behaviors in time, but it does not adequately represent spatial processes. Although Geographic Information System (GIS) and Remote Sensing (RS) are powerful tools for spatial analyses, they maintain an inherently static
Ecological systems modelling based on the unified biophysical measure of cosmic emergy in terms of embodied cosmic exergy is illustrated in this paper with ecological accounting, simulation and scenario analysis, by a case study for the regional socio-economic ecosystem associated with the municipality of Beijing. An urbanized regional ecosystem model with eight subsystems of natural support, agriculture, urban production, population, finance, land area, potential environmental impact, and culture is representatively presented in exergy circuit language with 12 state variables governing by corresponding ecodynamic equations, and 60 flows and auxiliary variables. To characterize the regional socio-economy as an ecosystem, a series of ecological indicators based on cosmic emergy are devised. For a systematic ecological account, cosmic exergy transformities are provided for various dimensions including climate flows, natural resources, industrial products, cultural products, population with educational hierarchy, and environmental emissions. For the urban ecosystem of Beijing in the period from 1990 to 2005, ecological accounting is carried out and characterized in full details. Taking 2000 as the starting point, systems modelling is realized to predict the urban evolution in a one hundred time horizon. For systems regulation, scenario analyses with essential policy-making implications are made to illustrate the long term systems effects of the expected water diversion and rise in energy price.
Scientific evidence suggests that economic activity is threatening global biodiversity in ways that could severely degrade nature's flow of ecosystem services. Yet, there is relatively little work in economics that addresses biodiversity loss. Some economists have called for better integration of economic and ecologicalmodels to address biodiversity and the attendant ecosystem services. Current integrated approaches in economics are discussed,
The recovery and continuance of native vegetation communities is the critical component of ecological restoration. As primary producers and basis of the food web, their success will influence and likely control the recovery and sustenance of all higher tropic levels. Intact ecosystems are perfectly designed to produce the vegetation dynamics that they produce. Hence, impacted or altered ecosystems can not be perfectly designed to produce the original vegetation. The alteration of the hydrologic system of the Florida Everglades is causing well-documented changes in the composition of the ecosystem. It is argued that this composition depends on the balance between three vegetation community types, defined here as sawgrass, cattails and periphyton. The factors that may be most critical in the success of the restoration are the factors that will restore the balance between these archetypes. These factors are identified as hydroperiod, water quality (phosphorous concentration) and fire. An investigation of ecological and hydrological models was conducted to evaluate suitability of application to ecological restoration scenarios, such as the vegetation community competition of the Florida Everglades. This investigation revealed aspects of three model types, defined here as ecosystem, hydrologic and competition, are necessary for such a simulation of ecological restoration. A comparison of how each model type treats the common factors of water flow, vegetation dynamics and climate inputs revealed avenues for extension of each model type to better capture the whole system dynamics.
The Register of Ecologicalmodels is a a meta-database for existing mathematical models in ecology. It is a cooperative service of the University of Kassel and the GSF - National research center for Environment and Health
Water quality and plankton dynamics, important indicators for the ecological state of a lake, are affected by many influence factors. To understand the behaviour of a lake under changing driving forces (such as nutrient loads or climatic change), modelling is an important resource. A model used for this purpose should represent the quantitative understanding of the dominant biogeochemical and ecological processes within a lake and be as universal as possible. With the Biogeochemical Ecologial LAke MOdel (BELAMO) it was tried to combine the description of biogeochemical processes in the lake with an ecologicalmodel. The results of its application to the lakes Greifensee (eutrophic), Lake Zurich (mesotrophic) and Walensee (oligotrophic) indicate that already a relatively simple plankton sub-model can lead to a quite high degree of universality (in the sense of applicability of the same model and parameter values to lakes of different trophic state). The box version of the model distinguishes the four mixed compartments epilimnion, hypolimnion and 2 sediment layers. It aims at a joint calculation of mass balances of nutrients, oxygen, organic particles, one group of phytoplankton and one group of zooplankton in a lake in all four compartments. The model was designed to explicitly describe the sediment processes, instead of considering their effect by source and sink terms at the bottom of the lake for substances exchanged between lake water and the sediment. Therefore the different mineralisation processes had to be quantified. Difficulties compassed the identification of aerobic, anoxic and anaerobic mineralisation rates while representing jointly the measured concentrations of oxygen, nitrate and organic material in the lake. The description of the lake by mixed compartments enhanced this difficulty, because the depth of the sediment layers determines maximal diffusion gradients for the entry of substances into the sediment. One further problem we had to cope with was the availability of concentration data only. The same concentrations can result from different fluxes that drive the dynamics in the lake. Different concentrations can have quite different sensitivities to external changes. An example for this are phosphate and algae. While the phosphate concentration responds quite fast to a decrease in phosphate input loading, the algae might not show this decrease directly. This is due to the ability of adaptation of the algal community and a parallel reaction of zooplankton. For this reason, the reduced turnover rates of phosphate do not necessarily lead to much smaller plankton concentrations. On a shorter time scale, phytoplankton and zooplankton can show faster variability than can be detected by monthly data. This makes it impossible to get a realistic description of short-term algal dynamics. To handle this problem when improving the model we conducted parameter calibrations that fit smoothed model results to smoothed data. This calibration technique avoids fitting the model to uncertain data peaks as well as rejecting parameter combinations resulting in model outputs that do not represent individual data peaks, but cover the main patterns of the measurements correctly. This pattern fitting technique led to a much better performance of the fit algorithm than fitting to the original data, which often resulted in simulations that covered some data peaks, but missed the basic annual and long-term pattern. In the end, long-term simulations for 20-30 years (depending on data availability for the different lakes) showed that good simulations are possible despite significantly changing driving forces. This is an indication of the good mechanistic representation of the processes in the lake. Nevertheless, as this behaviour depends critically on the chosen model parameter values, the predictive power of the model still needs further improvement.
A generalized ecologicmodel of a fertilized warm-water aquaculture pond is under development. The model is intended to represent the pond ecosystem and its response to external stimuli. The major physical, chemical and biological processes and parameters are included in the model. A total of 19 state variables are included in the model (dissolved oxygen, alkalinity, pH, ammonia, phytoplankton, etc.). The model is formulated as a system of mass balance equations. The equations include stimulatory and inhibitory effects of environmental parameters on processes taking place in the pond. The equations may be solved for the entire growth period and diurnal as well as seasonal fluctuations may be identified. The ultimate objective of the model is to predict the fish biomass that can be produced in a pond under a given set of environmental conditions.
Piedrahitu, R.H.; Brune, D.E.; Orlob, G.T.; Tchobanoglous, G.
|Describes a study of the effectiveness of computer-simulation programs in enhancing biology students' familiarity with ecologicalmodeling and concepts. Finds that computer simulations improved student comprehension of ecological processes expressed in mathematical form, but did not allow a full understanding of ecological concepts. Contains 28…
Korfiatis, K.; Papatheodorou, E.; Paraskevopoulous, S.; Stamou, G. P.
The U. S. Geological Survey has developed two separate models applicable to the southern Everglades. The Southern Inland and Coastal System (SICS) model is a hydrodynamic surface-water model modified for wetlands application, and was recently coupled to a ground-water model to account for leakage and salinity transfer. The Across Trophic Levels System Simulator (ATLSS) is a suite of ecologicalmodels
A nine year nitrogen (N) simulation (SOIL\\/SOILN) from a clay soil in central Sweden, carried out while the field was being converted to ecological farming, showed a good relationship (r = 0.91) between measured and simulated mineral N in the soil. Simulated nitrate leaching output of the model was as a mean 67% of measured leaching. Simulated as well as
We are attempting to integrate ecological and economic modeling and analysis in order to improve our understanding of regional systems, assess potential future impacts of various land-use, development, and agricultural policy options, and to better assess the value of ecological systems. Starting with an existing spatially articulated ecosystem model of the Patuxent River drainage basin in Maryland, we are adding
N. Bockstael; R. Costanza; I. Strand; W. Boynton; K. Bell; L. Wainger
Atmospheric scientists engaged in climate change research require a basic understanding of how ecological effects models incorporate climate. The report provides an overview of existing ecologicalmodels that might be used to model climate change effects on vegetation. Some agricultural models and statistical methods are also discussed. The weather input data requirements, weather simulation methods, and other model characteristics relevant to climate change research are described for a selected number of models. The ecologicalmodels are classified as biome, ecosystem, or tree models; the ecosystem models are further subdivided into species dynamics or process models. In general, ecologicalmodelers have had to rely on readily available meteorological data such as temperature and rainfall. Although models are becoming more sophisticated in their treatment of weather and require more kinds of data (such as wind, solar radiation, or potential evapotranspiration), modelers are still hampered by a lack of data for many applications. Future directions of ecological effects models and the climate variables that will be required by the models are discussed.
The bit-string Penna model is used to simulate the competition between an asexual parthenogenetic and a sexual population sharing the same environment. A newborn of either population can mutate and become a part of the other with some probability. In a stable environment the sexual population soon dies out. When an infestation by rapidly mutating genetically coupled parasites is introduced, however, sexual reproduction prevails, as predicted by the so-called Red Queen hypothesis for the evolution of sex.
A system dynamics production model illustrates feedbacks between economic growth and resource depletion. Man-made capital, renewable natural capital, nonrenewable natural capital, and human capital are factors of production in a Cobb–Douglas production function. Technology in production sets the overall level of efficiency in production. Feedbacks between production and factors of production, and biological and physical limits on the availability of
The image of a ball rolling along a series of hills and valleys is an effective heuristic by which to communicate stability concepts in ecology. However, the dynamics of this landscape model have little to do with ecological systems. Other landscape representations, however, are ...
In the study of consumers' evaluation of the service setting, laboratory experiments using environmental simulations provide researchers with a level of control that can otherwise be difficult to achieve in field studies. This article demonstrates that photographic slides and videotapes, used as environmental simulations in testing a theory of crowding, have ecological validity. The same theoretical model is tested with
We study multiple bifurcations and chaotic behavior of a discrete delay ecologicalmodel. New form of chaos for the 2-D map is observed: the combination of potential period doubling and reverse period-doubling leads to cascading bubbles.
A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...
The effect of weak solar activity generated disturbances on the ecological system has been investigated. The study is based on simulation of the tundra community `vegetation/lemmings/polar foxes'. The model was verified using the data on the West Taimir ecosystem. The summer duration determined from meteorological indices was taken as the input parameter of the model. If the effect was small enough in amplitude, the model demonstrated 3-year-long intervals between the maxima modulated by the 11-year-cycle. At the second stage of our study we used the real series of summer duration (from setting in to melting of the snow cover) in the region under consideration. When the real summer duration was included in the model, the spectrum displayed an 11-year component that was nearly as pronounced as the observed one. Since the data on summer duration used in the model were taken directly from meteorological stations without processing, the appearance of the 11-year periodicity in the model dynamics may be regarded as additional evidence for dependence of the meteorological series on solar activity.
Predicting outcomes of transgene flow from arable crops requires a system perspective that considers ecological and evolutionary processes within a landscape context. In Europe, the arable weed Raphanus raphanistrum is a potential hybridization partner of oilseed rape, and the two species are ecologically linked through the common herbivores Meligethes spp. Observations in Switzerland show that high densities of Meligethes beetles maintained by oilseed rape crops can lead to considerable damage on R. raphanistrum. We asked how increased insect resistance in R. raphanistrum – as might be acquired through introgression from transgenic oilseed rape – would affect seed production under natural herbivore pressure. In simulation experiments, plants protected against Meligethes beetles produced about twice as many seeds as unprotected plants. All stages in the development of reproductive structures from buds to pods were negatively affected by the herbivore, with the transition from buds to flowers being the most vulnerable. We conclude that resistance to Meligethes beetles could confer a considerable selective advantage upon R. raphanistrum in regions where oilseed rape is widely grown.
The image of a ball rolling along a series of hills and valleys is an effective heuristic by which to communicate stability\\u000a concepts in ecology. However, the dynamics of this landscape model have little to do with ecological systems. Other landscape\\u000a representations, however, are possible. These include the particle on an energy landscape, the potential landscape, and the\\u000a Lyapunov function
The study of complex ecological processes presents many difficulties for learners including the time frame in which it may take place and the complexity of the relationships involved. The learning outcomes and level of understanding of the underlying relationships for students studying such processes may be effectively supported and improved through the use of carefully designed simulations which provide the
|Reports on a test of Benjamin's ecologicalmodel of student satisfaction. Using an international, multi-institutional sample (N=2,307), the study yielded a fitted model of student life satisfaction in which females and males differed significantly. Social relationships and self-evaluations played a direct and central role in student satisfaction.…
We study, both analytically and numerically, models of ecological character displacement for two species that compete for the same set of food sources. These models include quantitative genetics and Lotka–Volterra type competition and are symmetric with respect to the two species. We allow for various shapes of the carrying capacity and the competition function, and we discuss under what general
I discuss a new simple framework that allows a more realistic modelling of speculation. The resulting model features expliciting position holding, contagion between predictability patterns, allows for an explicit measure of market inefficiency and substantiates the use of the minority game to study information ecology in financial markets.
Dramatically increased volumes of data from observational and experimental networks such as FLUXNET call for transformation of ecological research to increase its emphasis on quantitative forecasting. Ecological forecasting will also meet the societal need to develop better strategies for natural resource management in a world of ongoing global change. Traditionally, ecological forecasting has been based on process-based models, informed by data in largely ad hoc ways. Although most ecologicalmodels incorporate some representation of mechanistic processes, today’s ecologicalmodels are generally not adequate to quantify real-world dynamics and provide reliable forecasts with accompanying estimates of uncertainty. A key tool to improve ecological forecasting is data assimilation, which uses data to inform initial conditions and to help constrain a model during simulation to yield results that approximate reality as closely as possible. In an era with dramatically increased availability of data from observational and experimental networks, data assimilation is a key technique that helps convert the raw data into ecologically meaningful products so as to accelerate our understanding of ecological processes, test ecological theory, forecast changes in ecological services, and better serve the society. This talk will use examples to illustrate how data from FLUXNET have been assimilated with process-based models to improve estimates of model parameters and state variables; to quantify uncertainties in ecological forecasting arising from observations, models and their interactions; and to evaluate information contributions of data and model toward short- and long-term forecasting of ecosystem responses to global change.
Stochastic ecological network occupancy (SENO) models predict the probability that species will occur in a sample of an ecological\\u000a network. In this review, we introduce SENO models as a means to fill a gap in the theoretical toolkit of ecologists. As input,\\u000a SENO models use a topological interaction network and rates of colonization and extinction (including consumer effects) for\\u000a each
Application of the ecologicalmodel to children with behavioral problems focuses on the degree to which behavior matches the demands, expectations, or levels of tolerance of individuals in the environment. Such individuals as well as the child may need to change their behaviors. (DB)
In June 2007 the American Journal of Community Psychology published a special issue focused on theories, methods and interventions for systems change which included calls from the editors and authors for theoretical advancement in this field. We propose a conceptual model of systems change that integrates familiar and fundamental community psychology principles (succession, interdependence, cycling of resources, adaptation) and accentuates a process orientation. To situate our framework we offer a definition of systems change and a brief review of the ecological perspective and principles. The Ecological Process Model of Systems Change is depicted, described and applied to a case example of policy driven systems level change in publicly funded social programs. We conclude by identifying salient implications for thinking and action which flow from the Model. PMID:21203829
Peirson, Leslea J; Boydell, Katherine M; Ferguson, H Bruce; Ferris, Lorraine E
\\u000a This introductory chapter to a book on traffic simulation fundamentals is aimed at setting up a comprehensive framework for\\u000a simulation as a well-established and grounded OR technique and its specificities when applied to traffic systems; the main\\u000a approaches to traffic simulation and the principles of traffic simulationmodel building; the fundamentals of traffic flow\\u000a theory and its application to traffic
The niche concept is central to ecology but is often depicted descriptively through observing associations between organisms and habitats. Here, we argue for the importance of mechanistically modelling niches based on functional traits of organisms and explore the possibilities for achieving this through the integration of three theoretical frameworks: biophysical ecology (BE), the geometric framework for nutrition (GF) and dynamic energy budget (DEB) models. These three frameworks are fundamentally based on the conservation laws of thermodynamics, describing energy and mass balance at the level of the individual and capturing the prodigious predictive power of the concepts of ‘homeostasis’ and ‘evolutionary fitness’. BE and the GF provide mechanistic multi-dimensional depictions of climatic and nutritional niches, respectively, providing a foundation for linking organismal traits (morphology, physiology, behaviour) with habitat characteristics. In turn, they provide driving inputs and cost functions for mass/energy allocation within the individual as determined by DEB models. We show how integration of the three frameworks permits calculation of activity constraints, vital rates (survival, development, growth, reproduction) and ultimately population growth rates and species distributions. When integrated with contemporary niche theory, functional trait niche models hold great promise for tackling major questions in ecology and evolutionary biology.
Kearney, Michael; Simpson, Stephen J.; Raubenheimer, David; Helmuth, Brian
Liu, J., 1993. ECOLECON: An ECOLogical-ECONomic model for species conscrvation in complex forcst landscapes. Ecol. Modelling, 70: 63-87, An ECOLogical-ECONomic model (ECOLECON) has bccn developed to simulate animal population dynamics and economic rcvenucs in rcsponsc to diffcrcnt forest land- scape structurc and timber management scenarios. ECOLECON is a spatially-explicit, individual-based, and object-orientcd program. It is codcd in Borland C +
In May 2000, the Cerro Grande Fire burned approximately 17,200 ha in north-central New Mexico as the result of an escaped prescribed burn initiated by Bandelier National Monument. The interaction of large-scale fires, vegetation, and elk is an important management issue, but few studies have addressed the ecological implications of vegetative succession and landscape heterogeneity on ungulate populations following large-scale
Premature infants are at increased risk for poor health, feeding difficulties, and impaired mother-infant interaction leading to developmental delay. Social-environmental risks, such as poverty or minority status, compound these biologic risks, placing premature infants in double jeopardy. Guided by an ecologicalmodel, the Hospital-Home Transition: Optimizing Prematures’ Environment (H-HOPE) intervention combines the Auditory, Tactile, Visual, and Vestibular intervention with participatory guidance provided by a nurse and community advocate to address the impact of multiple risk factors on premature infants’ development.
Space–time autoregressive moving average (STARMA) processes can be used to represent a wide range of theoretical models of ecological variation and statistical models for analyzing ecological data. Many discrete-time, discrete-space ecological processes can be analyzed using STARMA theorems. As an example, one focus is on population genetic models, and using STARMA we obtain not only the usual spatial variance and
The Lake Suwa version of the comprehensive aquatic systems model (CASM_SUWA) was developed using field data from Lake Suwa and evaluated to examine the utility of CASM_SUWA for assessing the ecological risk of chemicals for aquatic ecosystems. The calibration of the parameters for the model provided that the established reference modelsimulation could reproduce complex seasonal biomass behavior of populations
Wataru Naito; Ken-ichi Miyamoto; Junko Nakanishi; Shigeki Masunaga; Steven M Bartell
The Across Trophic Levels System Simulator (ATLSS) is a suite of ecologicalmodels designed to assess the impact of changes in hydrology on biotic components of the southern Florida ecosystem. ATLSS implements a multimodeling approach that utilizes process models for lower trophic levels, structured popu- lation models for middle trophic levels (fish and macroinvertebrates), and individual-based models for large consumers.
Hydrologists and ecologists have been working in the Everglades on integrating a long- term hydrologic data network and a short-term ecological database to support ecologicalmodels of the habitat of the snail kite, a threatened and endangered bird. Data mining techniques, including artificial neural network (ANN) models, were applied to simulate the hydrology of snail kite habitat in the Water
PAUL A. CONRADS; EDWIN ROEHL; RUBY DAAMEN; WILEY M. KITCHENS
Although many biologists have embraced microbial model systems as tools to address genetic and physiological questions, the explicit use of microbial communities as model systems in ecology has traditionally been more restricted. Here, we highlight recent studies that use laboratory-based microbial model systems to address ecological questions. Such studies have significantly advanced our understanding of processes that have proven difficult
Christine M. Jessup; Rees Kassen; Samantha E. Forde; Ben Kerr; Angus Buckling; Paul B. Rainey; Brendan J. M. Bohannan
We introduce an implicit method for state and parameter estimation and apply it to a stochastic ecologicalmodel. The method uses an ensemble of particles to approximate the distribution of model solutions and parameters conditioned on noisy observations of the state. For each particle, it first determines likely values based on the observations, then samples around those values. This approach has a strong theoretical foundation, applies to nonlinear models and non-Gaussian distributions, and can estimate any number of model parameters, initial conditions, and model error covariances. The method is called implicit because it updates the particles without forming a predictive distribution of forward model integrations. As a point of comparison for different assimilation techniques, we consider examples in which one or more bifurcations separate the true parameter from its initial approximation. The implicit estimator is asymptotically unbiased, has a root-mean-squared error comparable to or less than the other methods, and is accurate even with small ensemble sizes. PMID:23292361
We modeled the ecological niche of a globally successful Bacillus anthracis sublineage in the United States, Italy and Kazakhstan to better understand the geographic distribution of anthrax and potential associations between regional populations and ecology. Country-specific ecological-niche models were developed and reciprocally transferred to the other countries to determine if pathogen presence could be accurately predicted on novel landscapes. Native models accurately predicted endemic areas within each country, but transferred models failed to predict known occurrences in the outside countries. While the effects of variable selection and limitations of the genetic data should be considered, results suggest differing ecological associations for the B. anthracis populations within each country and may reflect niche specialization within the sublineage. Our findings provide guidance for developing accurate ecological niche models for this pathogen; models should be developed regionally, on the native landscape, and with consideration to population genetics. Further genomic analysis will improve our understanding of the genetic-ecological dynamics of B. anthracis across these countries and may lead to more refined predictive models for surveillance and proactive vaccination programs. Further studies should evaluate the impact of variable selection of native and transferred models.
Mullins, Jocelyn C.; Garofolo, Giuliano; Van Ert, Matthew; Fasanella, Antonio; Lukhnova, Larisa; Hugh-Jones, Martin E.; Blackburn, Jason K.
Abstract: The Across Trophic Levels System Simulator (ATLSS) is a suite of ecologicalmodels designed toassess the impact of changes in hydrology on biotic components of the southern Florida ecosystem. ATLSSimplements a multimodeling approach that utilizes process models for lower trophic levels, structured populationmodels for middle trophic levels (fish and macroinvertebrates), and individual-based models for largeconsumers. ATLSS requires hydrologic input
This book presents the papers given at a conference on computerized simulation. Topics considered at the conference included expert systems, modeling in electric power systems, power systems operating strategies, energy analysis, a linear programming approach to optimum load shedding in transmission systems, econometrics, simulation in natural gas engineering, solar energy studies, artificial intelligence, vision systems, hydrology, multiprocessors, and flow models.
No abstract. Modeling has become an important tool in the study of ecological systems, as a scan of the table of contents of any major ecological journal makes abundently clear. The development of a conceptual model can be an integral part of designing and carrying out any resear...
Agricultural practices are essential for sustaining the human population, but at the same time they can directly disrupt ecosystem functioning. Ecological risk assessment (ERA) aims to estimate possible adverse effects of human activities on ecosystems and their parts. Current ERA practices, however, incorporate very little ecology and base the risk estimates on the results of standard tests with several standard species. The main obstacles for a more ecologically relevant ERA are the lack of clear protection goals and the inherent complexity of ecosystems that is hard to approach empirically. In this paper, we argue that the ecosystem services framework offers an opportunity to define clear and ecologically relevant protection goals. At the same time, ecologicalmodels provide the tools to address ecological complexity to the degree needed to link measurement endpoints and ecosystem services, and to quantify service provision and possible adverse effects from human activities. We focus on the ecosystem services relevant for agroecosystem functioning, including pollination, biocontrol and eutrophication effects and present modeling studies relevant for quantification of each of the services. The challenges of the ecosystem services approach are discussed as well as the limitations of ecologicalmodels in the context of ERA. A broad, multi-stakeholder dialog is necessary to aid the definition of protection goals in terms of services delivered by ecosystems and their parts. The need to capture spatio-temporal dynamics and possible interactions among service providers pose challenges for ecologicalmodels as a basis for decision making. However, we argue that both fields are advancing quickly and can prove very valuable in achieving more ecologically relevant ERA. PMID:21802704
Galic, Nika; Schmolke, Amelie; Forbes, Valery; Baveco, Hans; van den Brink, Paul J
Process-based models that can represent multiple and interacting processes provide a framework for combining field-based measure- ments with evolving science-based models of specific hydroecological processes. Use of these models, however, requires that the representation of processes and key assumptions involved be understood by the user community. This paper provides a full description of process implementation in the most recent version
In this paper, an ecologicalmodel is proposed to predict the effects of heavy metals on aquatic ecosystems. The bioavailable concentration of metals and a concept of toxicity strength (TS) are combined. The integrated ecologicalmodel relates the transport, distribution and speciation of heavy metals and their toxicity, and the effect of environmental variability on metal toxicity. It also emphasizes
This paper extends previous work to develop cognitive modeling for agent-based simulation of child maltreatment (CM). The developed model is inspired from parental efficacy, parenting stress, and the theory of planned behavior. It provides an explanatory, process-oriented model of CM and incorporates causality relationship and feedback loops from different factors in the social ecology in order for simulating the dynamics of CM. We describe the model and present simulation results to demonstrate the features of this model.
Understanding the factors that contribute to the formation of population genetic structure is a central goal of phylogeographic research, but achieving this goal can be complicated by the stochastic variance inherent to genetic processes. Statistical approaches to testing phylogeographic hypotheses accommodate this stochasticity by evaluating competing models of putative historical population structure, often by simulating null distributions of the expected variance. The effectiveness of these tests depends on the biological realism of the models. Information from the fossil record can aid in reconstructing the historical distributions of some taxa. However, for the majority of taxa, which lack sufficient fossils, paleodistributional modeling can provide valuable spatial-geographic data concerning ancestral distributions. Paleodistributional models are generated by projecting ecological niche models, which predict the current distribution of each species, onto a model of past climatic conditions. Here, we generate paleodistributional models describing the suitable habitat during the last glacial maximum for lineages from the mesic forests of the Pacific Northwest of North America, and use these models to generate alternative phylogeographic hypotheses. Coalescent simulations are then used to test these hypotheses to improve our understanding of the historical events that promoted the formation of population genetic structure in this ecosystem. Results from Pacific Northwest mesic forest organisms demonstrate the utility of these combined approaches. Paleodistribution models and population genetic structure are congruent across three amphibian lineages, suggesting that they have responded in a concerted manner to environmental change. Two other species, a willow and a water vole, despite being currently codistributed and having similar population genetic structure, were predicted by the paleodistributional model to have had markedly different distributions during the last glacial maximum. This suggests that congruent phylogeographic patterns can arise from incongruent ancestral distributions. Paleodistributional models introduce a much-needed spatial-geographic perspective to statistical phylogeography. In conjunction with coalescent models of population genetic structure, they have the potential to improve our understanding of the factors that promote population divergence and ultimately produce regional patterns of biodiversity. PMID:17542851
The simecol package provides an open structure to implement, simulate and share ecologicalmodels. A generalized object-oriented architecture improves readability and potential code re-use of models and makes simecol-models freely extendable and simple to use. The simecol package was implemented in the S4 class system of the programming language R. Reference applications, e.g. predator-prey models or grid models are provided
Modellers of biological, ecological, and environmental systems cannot take for granted the maxim 'simple means general means good'. We argue here that viewing simple models as the main way to achieve generality may be an obstacle to the progress of ecological research. We show how complex models can be both desirable and general, and how simple and complex models can be linked together to produce broad-scale and predictive understanding of biological systems. PMID:23827437
Evans, Matthew R; Grimm, Volker; Johst, Karin; Knuuttila, Tarja; de Langhe, Rogier; Lessells, Catherine M; Merz, Martina; O'Malley, Maureen A; Orzack, Steve H; Weisberg, Michael; Wilkinson, Darren J; Wolkenhauer, Olaf; Benton, Tim G
Along the Pacific Northwest coast, much of the estuarine habitat has been diked over the last century for agricultural land use, residential and commercial development, and transportation corridors. As a result, many of the ecological processes and functions have been disrupted. To protect coastal habitats that are vital to aquatic species, many restoration projects are currently underway to restore the estuarine and coastal ecosystems through dike breaches, setbacks, and removals. Information on physical processes and hydrodynamic conditions are critical for the assessment of the success of restoration actions. Restoration of a 160- acre property at the mouth of the Stillaguamish River in Puget Sound has been proposed. The goal is to restore native tidal habitats and estuary-scale ecological processes by removing the dike. In this study, a three-dimensional hydrodynamic model was developed for the Stillaguamish River estuary to simulate estuarine processes. The model was calibrated to observed tide, current, and salinity data for existing conditions and applied to simulate the hydrodynamic responses to two restoration alternatives. Responses were evaluated at the scale of the restoration footprint. Model data was combined with biophysical data to predict habitat responses at the site. Results showed that the proposed dike removal would result in desired tidal flushing and conditions that would support four habitat types on the restoration footprint. At the estuary scale, restoration would substantially increase the proportion of area flushed with freshwater (< 5 ppt) at flood tide. Potential implications of predicted changes in salinity and flow dynamics are discussed relative to the distribution of tidal marsh habitat.
Yang, Zhaoqing; Sobocinski, Kathryn L.; Heatwole, Danelle W.; Khangaonkar, Tarang; Thom, Ronald M.; Fuller, Roger
Using modeling and simulation techniques in game development can look\\u000d\\u000a\\u0009back on a comparably long history, starting in the early 1970s. In\\u000d\\u000a\\u0009contrast to this long tradition of combining games and simulations,\\u000d\\u000a\\u0009it is usually not made explicit which kind of simulation is used,\\u000d\\u000a\\u0009which models are fundament of the simulation, and which role the\\u000d\\u000a\\u0009simulation and the models have
The Packing SimulationModel is a microcomputer application program designed for researchers, extension personnel, bankers, packing managers, or other specialists who plan the operations of a packing facility or simulate its financial performance. PACKSIM produces pro forma financial statements for packing facilities based on flexible crop mixes and packing assumptions. Variations can be made in the product harvest schedule, price,
Constance L. Falk; Daniel S. Tilley; Raymond Joe Schatzer
|The research literature suggests that developing an understanding of ecosystems and their functioning is difficult. Learners are often asked to conduct ecological inquiries to attempt to foster such understanding. This project examines the understanding of students engaged in ecological inquiries as a model-based teaching and learning framework.…
Boulter, Carolyn; Buckley, Barbara; Walkington, Helen
|Background: A complementary ecologicalmodel of the coordinated school health program (CSHP) reflecting 20 years of evolved changes is proposed. Ecology refers to the complex interrelationship between intrapersonal factors, interpersonal processes and primary groups, institutional factors, community factors, and public policy. Methods: Public…
Scientists use models and simulations to help them visualize, explain, and make predictions and hypotheses about the structures, properties, and behaviors of phenomena (e.g., objects, materials, processes, systems). The extremely small size and complexity
Krajcik, Joseph S.; Sutherland, Leeann M.; Stevens, Shawn Y.
System Dynamic Continuous Computer Simulation sub model of the Business-production Shipbuilding Process - PSBP, which building started during 1991\\/92, in the frame work of the global science project with title \\
It is often spatial patterns in environmental and ecological variables that arouse interest and demand explanation. or environmental response variables, the causal influences of interacting environmental factors produce the patterns of interest. cological response variables by de...
Ecologicalmodels of human interaction can be used to study complex community problems that affect health disparities. These models allow researchers to study the components of a problem and understand how the problem can be ameliorated with nursing interventions. This article describes four research studies in which ecologicalmodels were used to either understand a phenomenon or design and test an intervention. The methods used were ethnography, descriptive/correlational, and quasi-experimental. All subjects were low-income women and children, largely of Hispanic ethnicity, residing in South Texas. The ecologicalmodels were derived from Bronfenbrenner's ecology of human development theory, epidemiology, Rubin's theory of developmental tasks of pregnancy, and Barnard's model of mother-child interaction. Heuristic models that represent reality allow researchers to divide a complex problem, such as health disparities, into manageable components. The influence of families, neighborhoods, and communities can be considered without losing sight of individuals. PMID:16061168
The FORTRAN77 ecological risk computer model--ECORSK.5--has been used to estimate the potential toxicity of surficial deposits of radioactive and non-radioactive contaminants to several threatened and endangered (T and E) species at the Los Alamos National Laboratory (LANL). These analyses to date include preliminary toxicity estimates for the Mexican spotted owl, the American peregrine falcon, the bald eagle, and the southwestern willow flycatcher. This work has been performed as required for the Record of Decision for the construction of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility at LANL as part of the Environmental Impact Statement. The model is dependent on the use of the geographic information system and associated software--ARC/INFO--and has been used in conjunction with LANL's Facility for Information Management and Display (FIMAD) contaminant database. The integration of FIMAD data and ARC/INFO using ECORSK.5 allows the generation of spatial information from a gridded area of potential exposure called an Ecological Exposure Unit. ECORSK.5 was used to simulate exposures using a modified Environmental Protection Agency Quotient Method. The model can handle a large number of contaminants within the home range of T and E species. This integration results in the production of hazard indices which, when compared to risk evaluation criteria, estimate the potential for impact from consumption of contaminants in food and ingestion of soil. The assessment is considered a Tier-2 type of analysis. This report summarizes and documents the ECORSK.5 code, the mathematical models used in the development of ECORSK.5, and the input and other requirements for its operation. Other auxiliary FORTRAN 77 codes used for processing and graphing output from ECORSK.5 are also discussed. The reader may refer to reports cited in the introduction to obtain greater detail on past applications of ECORSK.5 and assumptions used in deriving model parameters.
An information-based framework is presented for spatially explicit GIS-based ecologicalmodeling. Within this framework some\\u000a of the important issues and challenges of incorporating fuzzy sets in spatially explicit population models (SEPM) are discussed.\\u000a Examples of current work are used to illustrate the main issues and challenges facing the incorporation of fuzzy sets in ecological\\u000a modeling. Among the challenges to be
Present approaches to species invasions are reactive in nature. This scenario results in management that perpetually lags behind the most recent invasion and makes control much more difficult. In contrast, spatially explicit ecological niche modeling provides an effective solut...
The Oil Market Simulation (OMS) model is a LOTUS 1-2-3 spread-sheet that simulates the world oil market. OMS is an annual model that projects the world oil market through the year 2000 from a data base that begins in 1979. The geographic coverage includes all market economies, with net imports from the centrally planned economies taken as an assumption. The model estimates the effects of price changes on oil supply and demand and computes an oil price path over time that allows supply and demand to remain in balance within the market economies area as a whole. 2 figs., 2 tabs.
AGSIM is a large-scale econometric simulationmodel of regional crop and national livestock production in the United States. The model was initially developed to analyze the aggregate economic impacts of a wide variety issues facing agriculture, such as technological change, pest...
\\u000a As discussed in Ellenbroek and Cools, Animal models, this volume, the development of simulationmodels for schizophrenia has\\u000a gained momentum in the last decade through the recognition that not only symptoms, but also psychophysiological and psychological\\u000a disturbances of the disease can be used. This has led to the development of models like prepulse inhibition (PPI), P50 gating\\u000a and latent inhibition.
Bart A. Ellenbroek; Frank Sams-Dodd; Alexander R. Cools
Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulationmodels such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological
Volker Grimm; Eloy Revilla; Uta Berger; Florian Jeltsch; Wolf M. Mooij; Steven F. Railsback; Hans-Hermann Thulke; Jacob Weiner; Thorsten Wiegand; Donald L. DeAngelis
There is a brief review of models of succession: these are classified as verbal or descriptive, simulation, population dynamic, and Markovian. Many facets of the latter class of models are discussed, demonstrating that there are far more disadvantages to their use than apparent advantages. However, Markovian models do appear to have predictive ability, and it is also considered that the
A model is presented which applies current ecological succession theory to land?use management. A brief history of succession theory is followed by a more detailed summary of the recently developed facilitation, tolerance and inhibition succession models. The five steps of the management model, designed disturbance, selective colonization, inhibitory persistence, removal, and regeneration, are described. Application of the model for land?use
Symbolic machine learning methods induce explicitly represented symbolic models from data. The models can thus be inspected, modified, used and verified by human experts and have the potential to become part of the knowledge in the respective application domain. Applications of symbolic machine learning methods to ecologicalmodelling problems are numerous and varied, ranging from modelling algal growth in lagoons
Ecologic niche modeling (ENM) is a growing field with many potential applications to questions regarding the geography and ecology of disease transmission. Specifically, ENM has the potential to inform investigations concerned with the geography, or potential geography, of vectors, hosts, pathogens, or human cases, and it can achieve fine spatial resolution without the loss of information inherent in many other techniques. Potential applications and current frontiers and challenges are reviewed.
Fiber, a stand projection growth model, simulates the growth and structural development of stands in the Northeast. The internal structure of the model is specified and constructed by the ecological type classifications of sugar maple--ash, beech--red maple, oad--white pine, spruce--fir, hemlock--spruce, and cedar--black spruce. Guidelines are provided on operational procedures for the major commercial species growing on these different ecologic
Models must simplify the complexity of real marine pelagic ecosystems. How much simplicity is needed? A series of increasing numbers of state variables is used to illuminate this issue and to illustrate biogeochemical (element-conserving) and ecological (semi-freely dynamically interacting) models of the marine microplankton, defined as all organisms less than 200 ?m. The models are those of Riley [Riley, 1946.
Summary Recently there has been increased interest in modelling the association between aggregate dis- ease counts and environmental exposures measured, for example via air pollution monitors, at point locations. This paper has two aims: first we develop a model for such data in order to avoid ecological bias; second we illustrate that modelling the exposure surface and estimating exposures may
SUMMARY Recently, there has been an increased interest in modeling the association between aggregate disease counts and environmental exposures measured, for example via air pollution monitors, at point locations. This paper has two aims: first, we develop a model for such data in order to avoid ecological bias; second, we illustrate that modeling the exposure surface and estimating exposures may
|The purpose of this article is to examine models designed for the determination of a learning disability and compare them to specific criteria to determine whether the given diagnostic process is ecological in nature. The traditional child-centered deficit model (CCD), Relative Achievement Discrepancy model (RAD), and Responsiveness to…
Dean, Vincent J.; Burns, Matthew K.; Grialou, Tina; Varro, Patrick J.
Operationalizing prevention has been more difficult than presenting prevention theoretically. The author describes a model that has been used for training prevention workers and supervisors and for guiding prevention program development, implementation, and evaluation. The theoretical basis of the model is briefly reviewed and a description of the content of ecologicalmodel training sessions is presented. Training concentrates on the
A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...
A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...
Sklar, F.H., Costanza, R. and Day, J.W., Jr., 1985. Dynamic spatial simulationmodeling of coastal wetland habitat succession. Ecol. Modelling, 29: 261-281. To adequately model many ecological systems and management problems, spatial dy- namics need to be treated explicitly. A dynamic spatial simulationmodel composed of interacting cells was designed to project habitat changes as a function of marsh type,
Simulationmodels are currently being used for a multitude of purposes. Some simulationmodels are concise and well organized thereby facilitating their usage. However, some of these models may be quite lengthy and complex which causes development costs t...
|In this review, we propose a social ecological constraint model to study inclusion of overweight or obese students in physical education by integrating key concepts and assumptions from ecological constraint theory in motor development and social ecologicalmodels in health promotion and behavior. The social ecological constraint model proposes…
The Superfund reauthorization Act requires an ecological impact statement as part of each site assessment. his is difficult because of the hierarchical multiple dimensionality of ecosystems and becaus of the limited time and resources for the site's monitoring and evaluation. he ...
Despite the need to assess the ecological validity of jury simulation research before generalizing from simulations to the behavior of real jurors, surprisingly little jury research has directly addressed issues of validity. The present paper reviews the extant research on two aspects of the validity question—specifically, research that has compared different samples of mock jurors, and research that has manipulated
Ecological conceptual models are the result of the problem formulation phase of an ecological risk assessment, which is an important component of the Remedial Investigation process. They present hypotheses of how the site contaminants might affect the site ecology. The contaminant sources, routes, media, routes, and endpoint receptors are presented in the form of a flow chart. This guide is for preparing the conceptual models; use of this guide will standardize the models so that they will be of high quality, useful to the assessment process, and sufficiently consistent so that connections between sources of exposure and receptors can be extended across operable units (OU). Generic conceptual models are presented for source, aquatic integrator, groundwater integrator, and terrestrial OUs.
|This set of teaching aids consists of nine Audubon Nature Bulletins, providing teachers and students with informational reading on various ecological topics. The bulletins have these titles: Schoolyard Laboratories, Owls and Predators, The Forest Community, Life in Freshwater Marshes, Camouflage in the Animal World, Life in the Desert, The…
PROMODEL's simulationmodeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel® is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, and our latest release, ProModel PI
The effectiveness of an integrated socio-economic and ecologicalsimulationmodel for estimating patterns and rates of deforestation in Rondônia, Brazil is evaluated using Landsat data and landscape pattern metrics. The Percent Cleared, Contagion, and Fractal Dimension of image classifications are compared to those determined from model outputs. Results indicate that rates and spatial patterns of deforestation are similar between model
R. C. FROHN; K. C. McGWIRE; V. H. DALE; J. E. ESTES
The Nutrition and Physical Activity Program to Prevent Obesity and Other Chronic Diseases at the Centers for Disease Control and Prevention employs a five-level Social-EcologicalModel (SEM) to address and understand the issues of overweight and obesity (Hamre et al., 2006). The model suggests that there are multiple levels of influence, and that effective prevention and reduction programs should address
In this paper we complete the global qualitative analysis of a quartic ecologicalmodel. In particular, studying global bifurcations of singular points and limit cycles, we prove that the corresponding dynamical system has at most two limit cycles. The paper is based on the applications of Bifurcation Theory and can be used for modeling problems, where system parameters play a
In this paper, a complicated delayed ecologicalmodel is studied in detail. First, the parameter plane is divided into three different regions, in which there exist various fixed points of the model. Second, by using the center manifold theorem, it is shown that there exists the transcritical bifurcation rather than the saddle-node bifurcation with respect to the zero fixed point
A new type of particle simulationmodel based on the gyrophase-averaged Vlasov and Poisson equations is presented. The reduced system, in which particle gyrations are removed from the equations of motion while the finite Larmor radius effects are still preserved, is most suitable for studying low frequency microinstabilities in magnetized plasmas. It is feasible to simulate an elongated system (L/sub parallel/ >> L/sub perpendicular/) with a three-dimensional grid using the present model without resorting to the usual mode expansion technique, since there is essentially no restriction on the size of ..delta..x/sub parallel/ in a gyrokinetic plasma. The new approach also enables us to further separate the time and spatial scales of the simulation from those associated with global transport through the use of multiple spatial scale expansion. Thus, the model can be a very efficient tool for studying anomalous transport problems related to steady-state drift-wave turbulence in magnetic confinement devices. It can also be applied to other areas of plasma physics.
The bank vole (Myodes glareolus) is the natural host of Puumala virus (PUUV) in vast areas of Europe. PUUV is one of the hantaviruses which are transmitted to humans by infected rodents. PUUV causes a general mild form of hemorrhagic fever with renal syndrome (HFRS) called nephropathia epidemica (NE). Vector-borne and zoonotic diseases generally display clear spatial patterns due to different space-dependent factors. Land cover influences disease transmission by controlling both the spatial distribution of vectors or hosts, as well as by facilitating the human contact with them. In this study the use of ecological niche modelling (ENM) for predicting the geographical distribution of bank vole population on the basis of spatial climate information is tested. The Genetic Algorithm for Rule-set Prediction (GARP) is used to model the ecological niche of bank voles in Western Europe. The meteorological data, land cover types and geo-referenced points representing the locations of the bank voles (latitude/longitude) in the study area are used as the primary model input value. The predictive accuracy of the bank vole ecologic niche model was significant (training accuracy of 86%). The output of the GARP models based on the 50% subsets of points used for testing the model showed an accuracy of 75%. Compared with random models, the probability of such high predictivity was low (?(2) tests, p < 10(-6)). As such, the GARP models were predictive and the used ecologic niche model indeed indicates the ecologic requirements of bank voles. This approach successfully identified the areas of infection risk across the study area. The result suggests that the niche modelling approach can be implemented in a next step towards the development of new tools for monitoring the bank vole's population. PMID:23358234
Amirpour Haredasht, Sara; Barrios, Miguel; Farifteh, Jamshid; Maes, Piet; Clement, Jan; Verstraeten, Willem W; Tersago, Katrien; Van Ranst, Marc; Coppin, Pol; Berckmans, Daniel; Aerts, Jean-Marie
PROMODEL's simulationmodeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel® is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, Innovate™, and ProModel PI™ (for process
Over the past years several authors have used the approach of generalized modeling to study the dynamics of food chains and food webs. Generalized models come close to the efficiency of random matrix models, while being as directly interpretable as conventional differential-equation-based models. Here we present a pedagogical introduction to the approach of generalized modeling. This introduction places more emphasis
Justin D. Yeakel; Dirk Stiefs; Mark Novak; Thilo Gross
Consider the need to make a management decision about a declining animal population. Two models are available to help. Before a decision is made based on model results, the astute manager or policy maker may ask, "Do the models work?" Or, "Have the models been verified or validat...
PROMODEL's simulationmodeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, and our latest release, ProModel PI
Over the past 7 years, several authors have used the approach of generalized modeling to study the dynamics of food chains\\u000a and food webs. Generalized models come close to the efficiency of random matrix models, while being as directly interpretable\\u000a as conventional differential-equation-based models. Here, we present a pedagogical introduction to the approach of generalized\\u000a modeling. This introduction places more emphasis
Justin D. Yeakel; Dirk Stiefs; Mark Novak; Thilo Gross
Is individual-based modelling really a new approach in ecology? A large part of the uncertainty surrounding this question is a consequence of imprecisely delimited boundaries between classical and individual-based modelling. Genuine ‘individual-based’ models describe a population made up of individuals that may differ from one another; they also describe changes in numbers of individuals rather than in the population density,
Chaotic dynamics have been observed in a wide range of population models. In this study, the complex dynamics in a discrete-time ecologicalmodel of parasitoid-host-parasitoid are presented. The model shows that the superiority coefficient not only stabilizes the dynamics, but may strongly destabilize them as well. Many forms of complex dynamics were observed, including pitchfork bifurcation with quasi-periodicity, period-doubling cascade,
This paper incorporates the concept of ecological pyramid into the John's specific factor model of trade to examine comparative advantages, gains from trade, terms of trade, and income distributional effects of trade in the presence of non-market ecosystem services. Our results show that the market price undervalues the opportunity cost of land-intensive goods. The terms of trade, pattern of trade,
|Examines the cognition of five pairs of high school students over time as they built quantitative ecologicalmodels using STELLA software. Applies theories of the multifaceted nature of cognition to describe object-level, metalevel, and emotional dimensions of cognitive performance that help explain the observed differences among students'…
The relationship between preadolescent suicidality (ideation, threats, attempts) and subsequent adolescent suicidal behavior is well documented. We tested a six domain, ecological suicide risk model in a sample of 69 preadolescent outpatients (ages 5 to 12 years). We correlated items from each domain with “Suicidality” as measured by the Pfeffer Spectrum of Suicide Potential Scale. Three domains (Child Risk Factors,
We summarize our work on integration of an economy under imperfect competition with a simple Lotka-Volterra type ecologicalmodel. Firms and households operate within a single period planning horizon, thus there is no savings or investment. Wages are set by a dominant employer. P...
Based on Bronfenbrenner's (1999) ecological perspective, a longitudinal, prospective model of individual differences in the quality of home environment (Home Observation for Measurement of the Environment—HOME) was tested in a sample of 179 Brazilian children and their families. Perinatal measures of family socioeconomic status (SES) and child birth weight had direct effects on HOME at preschool age. As either family
Ebenézer A. de Oliveira; Fernando C. Barros; Luciana D. da Silva Anselmi; Cesar A. Piccinini
Simple discrete-time ecologicalmodels for a species with alternating reproduction and dispersal are shown to have complex transient dynamics. If the density dependence (nonlinearity) is strong enough, then the time required to reach the final dynamics is usually very long, approaching thousands of generations, and there are typically very sudden changes in the form of the dynamics. Apparent chaos can
Studies on natural populations and harvesting biological resources have led to the view, commonly held, that (i) populations exhibiting chaotic oscillations run a high risk of extinction; and (ii) a decrease in emigration \\/ exploitation may reduce the risk of extinction. Here we describe a simple ecologicalmodel with emigration \\/ depletion that shows behavior in contrast to this. This
Stochastic weather generators are useful tools for exploring the relationship between organisms and their environment. This paper describes a simple weather generator that can be used in ecologicalmodeling projects. We provide a detailed description of methodology, and links to full C++ source code (http:\\/\\/weathergen.sourceforge.net) required to implement or modify the generator. We argue that understanding the principles of weather
Andrew G. Birt; M. R. Valdez-Vivas; R. M. Feldman; C. W. Lafon; D. Cairns; Robert N. Coulson; M. Tchakerian; Weimin Xi; J. M. Guldin
More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...
More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...
More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...
More than 40 years ago, stable isotope analysis methods used in geochemistry began to be applied to ecological studies. One common application is using mathematical mixing models to sort out the proportional contributions of various sources to a mixture. Examples include contri...
|Dynamic Ecological Analysis (DEA) is a model of practice which increases a teams' efficacy by enabling the development of more effective interventions through collaboration and collective reflection. This process has proved to be useful in: a) clarifying thinking and problem-solving, b) transferring knowledge and thinking to significant parties,…
In recent years, there has been a growing interest among various sections of the society in the study of sustainability. Recently, a generalized mathematical model depicting a combined economic-ecological-social system has been proposed to help in the formal study of sustainabili...
Modeling and monitoring plankton functional types (PFTs) is challenged by insufficient amount of field measurements to ground-truth both plankton models and bio-optical algorithms. In this study, we combine remote sensing data and a dynamic plankton model to simulate an ecologically-sound spatial and temporal distribution of phyto-PFTs. We apply an innovative ecological indicator approach to modeling PFTs, and focus on resolving the question of diatom-coccolithophore co-existence in the subpolar high-nitrate and low-chlorophyll regions. We choose an artificial neural network as our modeling framework because it has the potential to interpret complex nonlinear interactions governing complex adaptive systems, of which marine ecosystems are a prime example. Using ecological indicators that fulfill the criteria of measurability, sensitivity and specificity, we demonstrate that our diagnostic model correctly interprets some basic ecological rules similar to ones emerging from dynamic models. Our time series highlight a dynamic phyto-PFT community composition in all high latitude areas, and indicate seasonal co-existence of diatoms and coccolithophores. This observation, though consistent with in situ and remote sensing measurements, was so far not captured by state-of-the-art dynamic models which struggle to resolve this "paradox of the plankton". We conclude that an ecological indicator approach is useful for ecologicalmodeling of phytoplankton and potentially higher trophic levels. Finally, we speculate that it could serve as a powerful tool in advancing ecosystem-based management of marine resources.
Palacz, A. P.; St. John, M. A.; Brewin, R. J. W.; Hirata, T.; Gregg, W. W.
There have been significant diversions of water from rivers and streams around the world; natural flow regimes have been perturbed by dams, barriers and excessive extractions. Many aspects of the ecological `health' of riverine systems have declined due to changes in water flows, which has stimulated the development of thinking about the maintenance and restoration of these systems, which we refer to as environmental flow methodologies (EFMs). Most existing EFMs cannot deliver information on the population viability of species because they: (1) use habitat suitability as a proxy for population status; (2) use historical time series (usually of short duration) to forecast future conditions and flow sequences; (3) cannot, or do not, handle extreme flow events associated with climate variability; and (4) assume process stationarity for flow sequences, which means the past sequences are treated as good indicators of the future. These assumptions undermine the capacity of EFMs to properly represent risks associated with different flow management options; assumption (4) is untenable given most climate-change predictions. We discuss these concerns and advocate the use of demographic modelling as a more appropriate tool for linking population dynamics to flow regime change. A `meta-species' approach to demographic modelling is discussed as a useful step from habitat based models towards modelling strategies grounded in ecological theory when limited data are available on flow-demographic relationships. Data requirements of demographic models will undoubtedly expose gaps in existing knowledge, but, in so doing, will strengthen future efforts to link changes in river flows with their ecological consequences.
Shenton, Will; Bond, Nicholas R.; Yen, Jian D. L.; Mac Nally, Ralph
There have been significant diversions of water from rivers and streams around the world; natural flow regimes have been perturbed by dams, barriers and excessive extractions. Many aspects of the ecological 'health' of riverine systems have declined due to changes in water flows, which has stimulated the development of thinking about the maintenance and restoration of these systems, which we refer to as environmental flow methodologies (EFMs). Most existing EFMs cannot deliver information on the population viability of species because they: (1) use habitat suitability as a proxy for population status; (2) use historical time series (usually of short duration) to forecast future conditions and flow sequences; (3) cannot, or do not, handle extreme flow events associated with climate variability; and (4) assume process stationarity for flow sequences, which means the past sequences are treated as good indicators of the future. These assumptions undermine the capacity of EFMs to properly represent risks associated with different flow management options; assumption (4) is untenable given most climate-change predictions. We discuss these concerns and advocate the use of demographic modelling as a more appropriate tool for linking population dynamics to flow regime change. A 'meta-species' approach to demographic modelling is discussed as a useful step from habitat based models towards modelling strategies grounded in ecological theory when limited data are available on flow-demographic relationships. Data requirements of demographic models will undoubtedly expose gaps in existing knowledge, but, in so doing, will strengthen future efforts to link changes in river flows with their ecological consequences. PMID:22543580
Shenton, Will; Bond, Nicholas R; Yen, Jian D L; Mac Nally, Ralph
Abstract. It is increasingly common for studies of animal ecology to use model-based predictions of environmental variables as explanatory or predictor variables, even though model prediction uncertainty is typically unknown. To demonstrate the potential for misleading inferences when model predictions with error are used in place of direct measurements, we compared snow water equivalent (SWE) and snow depth as predicted by the Snow Data Assimilation System (SNODAS) to field measurements of SWE and snow depth. We examined locations on elk (Cervus canadensis) winter ranges in western Wyoming, because modeled data such as SNODAS output are often used for inferences on elk ecology. Overall, SNODAS predictions tended to overestimate field measurements, prediction uncertainty was high, and the difference between SNODAS predictions and field measurements was greater in snow shadows for both snow variables compared to non-snow shadow areas. We used a simple simulation of snow effects on the probability of an elk being killed by a predator to show that, if SNODAS prediction uncertainty was ignored, we might have mistakenly concluded that SWE was not an important factor in where elk were killed in predatory attacks during the winter. In this simulation, we were interested in the effects of snow at finer scales (2) than the resolution of SNODAS. If bias were to decrease when SNODAS predictions are averaged over coarser scales, SNODAS would be applicable to population-level ecology studies. In our study, however, averaging predictions over moderate to broad spatial scales (9–2200 km2) did not reduce the differences between SNODAS predictions and field measurements. This study highlights the need to carefully evaluate two issues when using model output as an explanatory variable in subsequent analysis: (1) the model’s resolution relative to the scale of the ecological question of interest and (2) the implications of prediction uncertainty on inferences when using model predictions as explanatory or predictor variables.
Paul C Cross;Robert W Klaver;Angela Brennan;Scott Creel;Jon P. Beckmann;Megan Higgs;Brandon M. Scurlock
The objectives of these studies are to establish the comparative environmental behavior and chemical fate of chemical simulants. Laboratory studies were undertaken to establish: (1) deposition efficiency (deposition velocities, Vd) for receptor surfaces including plant foliage and soils; (2) dose/response relationships for important environmental components including plants and soil microflora; and (3) the environmental persistence of the simulants. Chemical agent simulants are employed for a range of testing and training activities where use of chemical agents is less than suitable from a safety and environmental standpoint. A variety of chemical simulant materials are used to simulate either nerve agents or blister agents. The following research describes the environmental effects and persistence of four simulants. These are the nerve agent stimulants diisopropyl methylphosphonate (DIMP), diisopropyl fluorophosphate (DFP), and bis (2-ethylhexyl) phosphonate (BIS), and the mustard stimulant 2-chloroethyl ethyl sulfide (CEES). The vapor pressures for DIMP, DFP, and CEES are relatively high, reported to be 0.17, 0.58 and 3.4 mm Hg, respectively; while that of BIS is substantially less at 5.8 /times/ 10/sup /minus/5/ mm Hg at 25/degree/C. The chemical characteristics of DFP and CEES are very similar to G/VX-agents and mustard, respectively, and are employed for materials evaluation under controlled conditions. However, their toxicity precludes their use in the environment. DIMP and BIS are currently used for testing in the open air. 3 figs., 3 tabs.
Cataldo, D.A.; Ligotke, M.W.; McVeety, B.D.; Fellows, R.J.; Bolton, H. Jr.; Li, S.W.; Van Voris, P.; Wentsel, R.S.
A Finite Element EcologicalModel (FEEM) has been set up by fully coupling a primitive equation finite element hydrodynamic model (FEM) to an ecologicalmodel derived from EUTRO, the ecological submodel contained in the water quality model WASP, released by US-EPA. The work required the ‘decoupling’ of EUTRO from WASP and its transformation into a standalone program, the testing of
Georg Umgiesser; Donata Melaku Canu; Cosimo Solidoro; Robert O. Ambrose
Abstract Reaction-diusion,models have been widely used to describe the dynamics of dispersing populations. However, many organisms disperse in ways that depend on environmental conditions or the densities of other populations. Those can include advection along environmental gradients and nonlinear diusion, among other possibilities. In this paper I will give a survey of some models involving conditional dispersal and discuss its
The aim of this paper is the study of the long-term behavior of population communities described by piecewise smooth models (known as Filippov systems). Models of this kind are often used to describe populations with selective switching between alternative habitats or diets or to mimic the evolution of an exploited resource where harvesting is forbidden when the resource is below
Ecological diversity indices are frequently applied to molecular profiling methods, such as terminal restriction fragment length polymorphism (T-RFLP), in order to detect differences in diversity of the microbial communities sampled. We performed simulations to determine whether diversity indices c...
Outdoor aquatic ditch mesocosms were treated with a range of pesticides to simulate various spray drift rates resulting from a typical crop protection program used in the cultivation of potatoes in The Netherlands. The main experimental aims of the present study were to provide information on the fate and ecological effects of drift of the pesticides into surface water and
Gertie HP Arts; Laura L Buijse-Bogdan; J Dick M Belgers; Rhenen-Kersten van C. H; Wijngaarden van R. P. A; Ivo Roessink; Steve J Maund; Brink van den P. J; Theo CM Brock
NRMRL-CIN-1531A Mata, T.M., Smith*, R.L., Young*, D., and Costa, C.A.V. "Simulation of Ecologically Conscious Chemical Processes: Fugitive Emissions versus Operating Conditions." Paper published in: CHEMPOR' 2001, 8th International Chemical Engineering Conference, Aveiro, Portu...
Bacterial biofilms are complex microbial depositions on immersed interfaces that form wherever the environmental conditions sustain microbial growth. Despite their name, biofilms can develop in highly irregular structures. Recently several mathematical concepts have been introduced to model these spatially structured microbial populations. Regardless of the type of model, they all have, even for microbially relatively simple systems, many parameters which generally are known at most approximately. We investigate the effect of uncertainties in model parameters on four morphological and four ecological output parameters using a nonlinear diffusion model for a biofilm in which two species compete for a shared nutrient. To this end we conduct an extensive computer simulation experiment for two different levels of data uncertainty, three different hydrodynamic conditions, and two different scenarios of bulk substrate availability. Our results indicate that input model parameter uncertainties have a much larger effect on ecological than on morphological output parameters. PMID:21669210
INS, the Integrated Network Simulation language, puts simulationmodeling into a network framework and automatically performs such programming activities as placing the problem into a next event structure, coding events, collecting statistics, monitoring ...
The current range of ecological habitats occupied by a species reflects a combination of the ecological tolerance of the species, dispersal limitation, and competition. Whether the current distribution of a species accurately reflects its niche has important consequences for the role of ecological niche modeling in predicting changes in species ranges as the result of biological invasions and climate change. We employed a detailed data set of species occurrence and spatial variation in biotic and abiotic attributes to model the niche of a native California annual plant, Collinsia sparsiflora. We tested the robustness of our model for both the realized and fundamental niche by planting seeds collected from four populations, representing two ecotypes, into plots that fully represented the five-dimensional niche space described by our model. The model successfully predicted which habitats allowed for C. sparsiflora persistence, but only for one of the two source ecotypes. Our results show that substantial niche divergence has occurred in our sample of four study populations, illustrating the importance of adequately sampling and describing within-species variation in niche modeling. PMID:17089652
Wright, Jessica W; Davies, Kendi F; Lau, Jennifer A; McCall, Andrew C; McKay, John K
The relationships among urbanization, stream hydraulics, and aquatic biology were investigated across a gradient of urbanization in 30 small basins in eastern Wisconsin, USA. Simulation of hydraulic metrics with 1-dimensional unsteady flow models was an effective means for mechanistically coupling the effects of urbanization with stream ecological conditions (i.e., algae, invertebrates, and fish). Urbanization, characterized by household, road, and urban land density, was positively correlated with the lowest shear stress for 2 adjacent transects in a reach for the low-flow summer (p < 0.001) and autumn (p < 0.01) periods. Urbanization also was positively correlated with Reynolds number and % exposed stream bed during months with moderate to low flows. Our study demonstrated the value of temporally and spatially explicit hydraulic models for providing mechanistic insight into the relationships between hydraulic variables and biological responses. For example, the positive correlation between filter-feeding invertebrate richness and minimum 2-transect shear stress observed in our study is consistent with a higher concentration of water-column particulates available for filtration. The strength of correlations between hydraulic and biological metrics is related to the time period (annual, seasonal, or monthly) considered. The hydraulic modeling approach, whether based on hourly or daily flow data, allowed documentation of the effects of a spatially variable response within a reach, and the results suggest that stream response to urbanization varies with hydraulic habitat type. ?? North American Benthological Society.
Agent-based modeling and simulation (ABMS) is a relatively new development that has found extensive use in areas such as social sciences, economics, biology, ecology etc. Can ABMS be effectively used in finding answers to complex construction systems? Our focus is to provide some answers to this question. Initial experimentation is conducted to understand the advantages of using ABMS either in
A model was developed to represent the establishment of a fire-sensitive woody species from seeds and subsequent survival and growth through five size classes. Simulations accurately represent structural changes associated with increased density and cover of the fire-sensitive Ashe juniper (Juniperus ashei, Buckholz) and provide substantial evidence for multiple steady states and ecological thresholds. Without fire, Ashe juniper increases and
Samuel D. Fuhlendorf; Fred E. Smeins; William E. Grant
Based on the physico-biophysical considerations, mathematical analysis and some approximate formulations generally adopted in meteorology and ecology, an ecological dynamic model of grassland is developed. The model consists of three interactive variables, i.e. the biomass of living grass, the biomass of wilted grass, and the soil wetness. The major biophysical processes are represented in parameterization formulas, and the model parameters can be determined inversely by using the observational climatological and ecological data. Some major parameters are adjusted by this method to fit the data (although incomplete) in the Inner Mongolia grassland, and other secondary parameters are estimated through sensitivity studies. The model results are well agreed with reality, e.g., (i) the maintenance of grassland requires a minimum amount of annual precipitation (approximately 300 mm); (ii) there is a significant relationship between the annual precipitation and the biomass of living grass; and (iii) the overgrazing will eventually result in desertification. A specific emphasis is put on the shading effect of the wilted grass accumulated on the soil surface. It effectively reduces the soil surface temperature and the evaporation, hence benefits the maintenance of grassland and the reduction of water loss in the soil. PMID:15844356
Zeng, Xiaodong; Wang, Aihui; Zhao, Gang; Shen, Samuel S P; Zeng, Xubin; Zeng, Qingcun
Analysis of agricultural ecology and environment is based on the data of agricultural resources, which are obtained by RS monitoring. The over-exploitation of farmlands will cause structural changes of the soil composition, and damage the planting environment and the agro-ecosystem. Through the research on the dynamic monitoring methods of multitemporal RS images and GIS technology, the crop growth status, crop acreage and other relevant information in agricultural production are extracted based on the monitor and analysis of the conditions of the fields and crop growth. The agro-ecological GIS platform is developed with the establishment of the agricultural resources management database, which manages spatial data, RS data and attribute data of agricultural resources. Using the RS, GIS analysis results, the reasons of agro-ecological destruction are analyzed and the evaluation methods are established. This paper puts forward the concept of utilization capacity of farmland, which describes farmland space for development and utilization that is influenced by the conditions of the land, water resources, climate, pesticides and chemical fertilizers and many other agricultural production factors. Assessment model of agricultural land use capacity is constructed with the help of Fuzzy. Assessing the utilization capacity of farmland can be helpful to agricultural production and ecological protection of farmland. This paper describes the application of the capacity evaluation model with simulated data in two aspects, namely, in evaluating the status of farmland development and utilization and in optimal planting.
Anthrax continues to cause significant mortalities in livestock, wildlife and humans worldwide. In Zimbabwe, anthrax outbreaks have been reported almost annually over the past four decades. In this study we tested whether anthrax outbreak data and a set of environmental variables can be used to predict the ecological niche for Bacillus anthracis using maximum entropy modelling for species geographical distribution (Maxent). Confirmed geo-referenced anthrax outbreaks data for the period 1995-2010 were used as presence locations and a set of environmental parameters; precipitation, temperature, vegetation biomass, soil type and terrain as predictor variables. Results showed that the environmental variables can adequately predict the ecological niche of B. anthracis (AUC for test data=0.717, p<0.001), with soil type as the most important predictor followed by variance of vegetation biomass and maximum temperature. These results imply that the model we tested may be used by animal health authorities in devising better control strategies for anthrax. PMID:23726015
Chikerema, S M; Murwira, A; Matope, G; Pfukenyi, D M
This paper discusses verification and validation of simulationmodels. The different approaches to deciding model validity am presented; how model verification and validation relate to the model development process are discussed; various validation techniques are defined, conceptual model validity, model verification, operational validity, and data validity are described; ways to document results are given; and a recommended procedure is presented.
Allelopathy arises from the release of chemicals by one plant species that affect other species in its vicinity, usually to their detriment. Allelopathic effects have been demonstrated to be limiting factors for species distributions and ecological processes in some natural or agricultural communities. Based on the biphasic hormetic responses of plants to allelochemicals, ecological-limiting-factor models were introduced into the An-Johnson-Lovett hormesis model to improve modelling the phenomenon of allelopathic hormesis and to better reflect the nature of allelopathy as a limiting factor in ecological processes. Outcomes of the models have been compared for several sets of experimental data from the literature and good agreement between the models and data was observed, which indicates that the new models give some insight into the ecological mechanisms involved and may provide more options for modelling the allelopathic phenomenon as well as platforms for further research on plant allelopathic hormesis.
Liu, Yinghu; Chen, Xiaoqiu; Duan, Shunshan; Feng, Yuanjiao; An, Min
Since the 1980s, ecologicalmodels of health promotion have generated a great deal of enthusiasm among researchers and interventionists. These models emerged from conceptual developments in other fields, and only selected elements of the ecological approach have been integrated into them. In this article, we describe the tenets of the ecological approach and highlight those aspects that have been integrated
Since the 1980s, ecologicalmodels of health promotion have generated a great deal of enthusiasm among researchers and interventionists. These models emerged from conceptual developments in other fields, and only selected elements of the ecological approach have been integrated into them. In this article, we describe the tenets of the ecological approach and highlight those aspects that have been integrated
Population dynamic modelling often entails parameterizing quite sophisticated biological and ecological mechanisms. For models of moderate mechanistic complexity, this has traditionally been done in an \\
Eco-genetic individual-based models involve tracking the ecological dynamics of simulated individual organisms that are in part characterized by heritable parameters. We developed an eco-genetic individual-based model to explore ecological and evolutionary interactions of fish growth and maturation schedules. Our model is flexible and allows for exploration of the effects of heritable growth rates (based on von Bertalanffy and biphasic growth patterns), heritable maturation schedules (based on maturation reaction norm concepts), or both on individual- and population-level traits. In baseline simulations with rather simple ecological trade-offs and over a relatively short time period (<200 simulation years), simulated male and female fish evolve differential genetic growth and maturation. Further, resulting patterns of genetically determined growth and maturation are influenced by mortality rate and density-dependent processes, and maturation and growth parameters interact to mediate the evolution of one another. Subsequent to baseline simulations, we conducted experimental simulations to mimic fisheries harvest with two size-limits (targeting large or small fish), an array of fishing mortality rates, and assuming a deterministic or stochastic environment. Our results suggest that fishing with either size-limit may induce considerable changes in life-history trait expression (maturation schedules and growth rates), recruitment, and population abundance and structure. However, targeting large fish would cause more adverse genetic effects and may lead to a population less resilient to environmental stochasticity.
A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.
Can markets assist by providing support for ecological restoration, and if so, under what conditions? The first step in addressing this question is to develop a consistent methodology for economic evaluation of ecological restoration projects. A risk analysis process was followed in which a system dynamics model was constructed for eight diverse case study sites where ecological restoration is currently being pursued. Restoration costs vary across each of these sites, as do the benefits associated with restored ecosystem functioning. The system dynamics modelsimulates the ecological, hydrological and economic benefits of ecological restoration and informs a portfolio mapping exercise where payoffs are matched against the likelihood of success of a project, as well as a number of other factors (such as project costs and risk measures). This is the first known application that couples ecological restoration with system dynamics and portfolio mapping. The results suggest an approach that is able to move beyond traditional indicators of project success, since the effect of discounting is virtually eliminated. We conclude that systems dynamic modelling with portfolio mapping can guide decisions on when markets for restoration activities may be feasible. PMID:23524327
Crookes, D J; Blignaut, J N; de Wit, M P; Esler, K J; Le Maitre, D C; Milton, S J; Mitchell, S A; Cloete, J; de Abreu, P; Fourie nee Vlok, H; Gull, K; Marx, D; Mugido, W; Ndhlovu, T; Nowell, M; Pauw, M; Rebelo, A
Predicting abundance across a species' distribution is useful for studies of ecology and biodiversity management. Modeling of survey data in relation to environmental variables can be a powerful method for extrapolating abundances across a species' distribution and, consequently, calculating total abundances and ultimately trends. Research in this area has demonstrated that models of abundance are often unstable and produce spurious estimates, and until recently our ability to remove detection error limited the development of accurate models. The N-mixture model accounts for detection and abundance simultaneously and has been a significant advance in abundance modeling. Case studies that have tested these new models have demonstrated success for some species, but doubt remains over the appropriateness of standard N-mixture models for many species. Here we develop the N-mixture model to accommodate zero-inflated data, a common occurrence in ecology, by employing zero-inflated count models. To our knowledge, this is the first application of this method to modeling count data. We use four variants of the N-mixture model (Poisson, zero-inflated Poisson, negative binomial, and zero-inflated negative binomial) to model abundance, occupancy (zero-inflated models only) and detection probability of six birds in South Australia. We assess models by their statistical fit and the ecological realism of the parameter estimates. Specifically, we assess the statistical fit with AIC and assess the ecological realism by comparing the parameter estimates with expected values derived from literature, ecological theory, and expert opinion. We demonstrate that, despite being frequently ranked the "best model" according to AIC, the negative binomial variants of the N-mixture often produce ecologically unrealistic parameter estimates. The zero-inflated Poisson variant is preferable to the negative binomial variants of the N-mixture, as it models an ecological mechanism rather than a statistical phenomenon and generates reasonable parameter estimates. Our results emphasize the need to include ecological reasoning when choosing appropriate models and highlight the dangers of modeling statistical properties of the data. We demonstrate that, to obtain ecologically realistic estimates of abundance, occupancy and detection probability, it is essential to understand the sources of variation in the data and then use this information to choose appropriate error distributions. PMID:19425427
The defense budget is shrinking. Weapon systems are getting more complex. Test requirements are increasing. The training and war gaming scenarios are getting more demanding as fielded systems and training simulators are integrated to support combined arms training. To cope with these requirements and still stay within the budget, the Department of Defense is relying on modeling and simulation. The state of the modeling and simulation (M&S) art has advanced to the point where a user can now create incredibly realistic, extremely detailed models which can augment test and evaluation, support the acquisition process, enhance training and war gaming, facilitate intelligence gathering, and support detailed engineering.
Analyses of ecological data should account for the uncertainty in the process(es) that generated the data. However, accounting for these uncertainties is a difficult task, since ecology is known for its complexity. Measurement and\\/or process errors are often the only sources of uncertainty modeled when addressing complex ecological problems, yet analyses should also account for uncertainty in sampling design, in
Noel Cressie; Catherine A. Calder; James S. Clark; Jay M. Ver Hoef; Christopher K. Wikle
The paper discusses an ecologicalmodel of assessment (i.e., one which examines the interaction between the child and his environment) and how it might be used with emotionally disturbed adolescents. A literature review focuses on current trends in assessment; the origins of the ecological perspective; and the ecological perspective in the school…
This research addresses the state of the art in nanorobot design and simulation focusing on the leukemia disease as well as ongoing applications on addressing the challenges posed by cancer treatment, especially chemotherapy. Nanotechnology and cancer biology, along with a new concept to leukemia treatment are the basis for nanorobot design. Robot architecture consists of Body, Ultrasonic Sensors, Folate material
Arosha Senanayake; R. G. Sirisinghe; Phang Shih Mun
The ecosystem service concept has emphasized the role of people within socio-ecological systems (SESs). In this paper, we review and discuss alternative ways of representing people, their behaviour and decision-making processes in SES models using an agent-based modelling (ABM) approach. We also explore how ABM can be empirically grounded using information from social survey. The capacity for ABM to be generalized beyond case studies represents a crucial next step in modelling SESs, although this comes with considerable intellectual challenges. We propose the notion of human functional types, as an analogy of plant functional types, to support the expansion (scaling) of ABM to larger areas. The expansion of scope also implies the need to represent institutional agents in SES models in order to account for alternative governance structures and policy feedbacks. Further development in the coupling of human-environment systems would contribute considerably to better application and use of the ecosystem service concept.
Rounsevell, M. D. A.; Robinson, D. T.; Murray-Rust, D.
the context of stream ecology. Within this context, we summarise the key innovations of a new family of spatial statistical models that describe spatial relationships in DENs. Finally, we discuss how different network analyses may be combined to address more complex and novel research questions. While our main focus is streams, the taxonomy of network analyses is also relevant anywhere spatial patterns in both network and 2-D space can be used to explore the influence of multi-scale processes on biota and their habitat (e.g. plant morphology and pest infestation, or preferential migration along stream or road corridors).
Peterson, Erin E.; Ver Hoef, Jay M.; Isaak, Dan J.; Falke, Jeffrey A.; Fortin, Marie-Josée; Jordon, Chris E.; McNyset, Kristina; Monestiez, Pascal; Ruesch, Aaron S.; Sengupta, Aritra; Som, Nicholas; Steel, E. Ashley; Theobald, David M.; Torgersen, Christian E.; Wenger, Seth J.
A difficulty in using diffusion models to predict large scale animal population dispersal is that individuals move differently based on local information (as opposed to gradients) in differing habitat types. This can be accommodated by using ecological diffusion. However, real environments are often spatially complex, limiting application of a direct approach. Homogenization for partial differential equations has long been applied to Fickian diffusion (in which average individual movement is organized along gradients of habitat and population density). We derive a homogenization procedure for ecological diffusion and apply it to a simple model for chronic wasting disease in mule deer. Homogenization allows us to determine the impact of small scale (10-100 m) habitat variability on large scale (10-100 km) movement. The procedure generates asymptotic equations for solutions on the large scale with parameters defined by small-scale variation. The simplicity of this homogenization procedure is striking when compared to the multi-dimensional homogenization procedure for Fickian diffusion,and the method will be equally straightforward for more complex models. PMID:21194012
Garlick, Martha J; Powell, James A; Hooten, Mevin B; McFarlane, Leslie R
Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulationmodels such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecologicalmodeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.
Grimm, Volker; Revilla, Eloy; Berger, Uta; Jeltsch, Florian; Mooij, Wolf M.; Railsback, Steven F.; Thulke, Hans-Hermann; Weiner, Jacob; Wiegand, Thorsten; DeAngelis, Donald L.
For the modeling of systems, the computers are more and more used while the other "media" (including the human intellect) carrying the models are abandoned. For the modeling of knowledges, i.e. of more or less general concepts (possibly used to model systems composed of instances of such concepts), the object-oriented programming is nowadays widely used. For the modeling of processes existing and developing in the time, computer simulation is used, the results of which are often presented by means of animation (graphical pictures moving and changing in time). Unfortunately, the object-oriented programming tools are commonly not designed to be of a great use for simulation while the programming tools for simulation do not enable their users to apply the advantages of the object-oriented programming. Nevertheless, there are exclusions enabling to use general concepts represented at a computer, for constructing simulationmodels and for their easy modification. They are described in the present paper, together with true definitions of modeling, simulation and object-oriented programming (including cases that do not satisfy the definitions but are dangerous to introduce misunderstanding), an outline of their applications and of their further development. In relation to the fact that computing systems are being introduced to be control components into a large spectrum of (technological, social and biological) systems, the attention is oriented to models of systems containing modeling components. PMID:10803299
The usefulness of water quality simulationmodels for environmental management is explored with a focus on prediction uncertainty. Ecological risk and environmental analysis often involve scientific assessments that are highly uncertain. Still, environmental manage- ment decisions are being made, often with the support of a mathematical simulationmodel. In the area of pollutant transport and fate in surface waters, few
Land use change is one of the major factors affecting global environmental conditions. Prevalent types of land-use change include replacing forests with agriculture, mines or ranches; forest degradation from collection of firewood; and forest logging. A global effect of wide-scale deforestation is an increase in atmospheric carbon dioxide concentration, which may affect climate. Regional effects include loss of biodiversity and disruption of hydrologic regimes. Local effects include soil erosion, siltation and decreases in soil fertility, loss of extractive reserves, and disruption of indigenous people. Modeling land use change requires combining socioeconomic and ecological factors because socioeconomic forces frequently initiate land-use change and are affected by the subsequent ecological degradation. This paper describes a modeling system that integrates submodels of human colonization and impacts to estimate patterns and rates of deforestation under different immigration and land use scenarios. Immigration which follows road building or paving is a major factor in the rapid deforestation of previously inaccessible areas. Roads facilitate colonization, allow access for large machines, and provide transportation routes for mort of raw materials and produce.
Dale, V.H.; Pedlowski, M.A.; O'Neill, R.V.; Southworth, F.
The per capita ecological footprint (EF) is one of the most widely recognized measures of environmental sustainability. It aims to quantify the Earth's biological resources required to support human activity. In this paper, we summarize relevant previous literature, and present five factors that influence per capita EF. These factors are: National gross domestic product (GDP), urbanization (independent of economic development), distribution of income (measured by the Gini coefficient), export dependence (measured by the percentage of exports to total GDP), and service intensity (measured by the percentage of service to total GDP). A new ecological footprint model based on a support vector machine (SVM), which is a machine-learning method based on the structural risk minimization principle from statistical learning theory was conducted to calculate the per capita EF of 24 nations using data from 123 nations. The calculation accuracy was measured by average absolute error and average relative error. They were 0.004883 and 0.351078% respectively. Our results demonstrate that the EF model based on SVM has good calculation performance. PMID:22291949
Rapid disappearance and deterioration of wetlands as a consequence of increasing human utilization coupled with growing recognition by the scientific community of the ecological importance of these areas indicate the need to investigate ecologically sound...
The analysis of socio-ecological systems requires new, qualitatively distinct, evaluation schemes and appropriate investigation tools that enable an integrated assessment of ecological, social, and economic factors since human land use is a major force driving landscape change, landscape dynamics can be better understood in the context of complex social-ecological systems (SESs). Tourist resorts are deemed as socio-ecological systems, and tourism
D. Lacitignola; I. Petrosillo; M. Cataldi; G. Zurlini
Industrial ecology education is being developed and delivered predominantly within the domains of engineering and management. Such an approach could prove somewhat limiting to the broader goal of developing industrial ecology as an integrated knowledge base inclusive of diverse disciplines, contributing to sustainable development. This paper hypothesizes that industrial ecology could be optimally delivered across broader disciplines if it were
Sustainable development has become a central part of the agenda in the building design professions; however, in recent years, the concept of ecologically sustainable development has gained ground which aims to balance both economic and environmental facets of sustainability. This has necessitated new approaches to ecological sustainable design that includes ecological facets to design. Such a design approach that draws
For the broad understanding of sustainable development, items such as seasonal change, timing of restrained harvesting and the rate of regeneration of natural resources, as well as the theories of population growth are crucial. Similarly, in the world of computing as a whole and computing simulation in particular, three important components of models are theory, data and program. A model
Medical and health educational services are insufficient to control AIDS risk behavior. A new conceptual model that can guide more effective behavioral change strategies for whole communities is required to modify sexual practices and control the AIDS epidemic. We integrated learning theories with an ecologicalmodel to create a behavioral?ecological conceptual model of sexual risk behavior. We assumed a developmental
Melbourne F. Hovell; Eva R. Hillman; Elaine Blumberg; Carol Sipan; Cathie Atkins; C. Richard Hofstetter; C. Arthur Myers
The area of research is included in the European prioritary fundamental research in geometry, partial differential equations and mathematical modeling of engineering problems. The mathematical research, the solving, the optimization and the software methods will be integrated in the prioritary European themes, such as the use of the eolian and solar energy or fluid flows in the production of electric,
Ecological and socioeconomic data were integrated to study landscape change for the Dungeness River basin in the Olympic Peninsula, Washington State. A multinomial logit procedure was used to evaluate twenty-two maps representing various data themes to derive transition probabilities of land cover change. Probabilities of forest disturbance were greater on private land than public. Between 1975 and 1988, forest cover increased, grassy/brushy covers decreased, and the number of forest patches increased about 30%. Simulations were run to estimate future land cover. These results were represented as frequency distributions for proportion cover and patch characteristics.
Flamm, R.O. (Florida Marine Research Institute, St. Petersburg, FL (United States)); Gottfried, R. (Univ. of the South, Sewanee, TN (United States)); Lee, R.G.; Naiman, R.J. (Univ. of Washington, Seattle, WA (United States)); Turner, M.G. (Oak Ridge National Laboratory, TN (United States)); Wear, D. (USDA Forest Service, Research Triangle Park, NC (United States))
\\u000a The monitoring of irrigation requirements at district or regional scale can be based on the use of ecological process-based\\u000a models and remote sensing data. The former simulates the time evolution (usually at daily scale) of the main biophysical variables\\u000a which determine crop photosynthesis and water consumption rates; the latter allows to provide the spatial distribution of\\u000a these variables over a
Marco Acutis; Michele Rinaldi; Francesco Mattia; Alessia Perego
This work investigates the Black Sea ecosystem and the changes it had undergone in the second half of the 20th century from a fisheries perspective using Ecopath, a widely adopted fisheries model. Different states of the Black Sea ecosystem were modeled using 5 simulation scenarios: Simulation 1, represents the quasi-pristine conditions of the Black Sea ecosystem during early 1960's; Simulation 2, represents the over-enrichment period of the ecosystem during early 1980's before the fisheries collapse and the outburst of alien ctenophore Mnemiopsis leidyi; Simulation 3, represents the changes in the ecosystem along with the outburst of Mnemiopsis in 1989; Simulation 4, represents the aftermath effects in the components of the Black Sea ecosystem just after the collapse of the fisheries; and Simulation 5, represents the recovery period of the fish stocks in the very beginning of the 1990's. According to the results of the model runs, it was found that the Black Sea ecosystem in its quasi-pristine conditions during early 1960's was top-down controlled. The piscivorous pelagic fish and dolphins exerted predation pressure on small pelagic fish species and suppressed their over-development. Our findings suggest that after the removal of these top predators from the ecosystem due to fishing and whaling, the small pelagic fish species had the opportunity to thrive themselves along with the over-enrichment of the Black Sea and reached high biomass levels in 1980's. Small pelagic fishes prevailed in the Black Sea ecosystem until the highly debated outburst of alien ctenophore Mnemiopsis leidyi. In 1989, the biomass of small pelagic fish species declined drastically and their population did not recover until the very beginning of 1990's due to various ecological and anthropogenic effects put forward by the outcomes of the simulations.
Many problems in applied science and engineering involve physical phenomena that behave randomly in time and/or space. Examples are diverse and include turbulent flow over an aircraft wing, Earth climatology, material microstructure, and the financial markets. Mathematical models for these random phenomena are referred to as stochastic processes and/or random fields, and Monte Carlo simulation is the only general-purpose tool for solving problems of this type. The use of Monte Carlo simulation requires methods and algorithms to generate samples of the appropriate stochastic model; these samples then become inputs and/or boundary conditions to established deterministic simulation codes. While numerous algorithms and tools currently exist to generate samples of simple random variables and vectors, no cohesive simulation tool yet exists for generating samples of stochastic processes and/or random fields. There are two objectives of this report. First, we provide some theoretical background on stochastic processes and random fields that can be used to model phenomena that are random in space and/or time. Second, we provide simple algorithms that can be used to generate independent samples of general stochastic models. The theory and simulation of random variables and vectors is also reviewed for completeness.
A set of epizootiological models describing the influence of a microsporidian disease on the population dynamics of an herbivorous insect demonstrate the similarities and differences between the three major approaches now available for ecologicalmodeling. Simulationmodeling allows the incorporation of randomness or the timing of discrete events in the temporal dynamics. More complex models incorporating both temporal and spatial dynamics in variable and heterogeneous environments require the use of supercomputers. Under a number of realistic circumstances, the qualitative predictions of the approaches may differ.
The development of ecologically sound water allocation strategies that account for the needs of riverine ecosystems is a pressing\\u000a issue, especially in semiarid river basins. In the Aral Sea Basin, a search for strategies to mitigate ecological and socioeconomic\\u000a deterioration has been in process since the early 1990s. The Geographic Information System–based simulation tool TUGAI has\\u000a been developed to support
Maja Schlüter; Nadja Rüger; Andre G. Savitsky; Nina M. Novikova; Michael Matthies; Helmut Lieth
This paper investigates a discrete-time host–parasitoid ecologicalmodel with Hassell growth function for the host by qualitative analysis and numerical simulation. Local stability analysis of the system is carried out. Many forms of complex dynamics are observed, including chaotic bands with periodic windows, pitchfork and tangent bifurcations, attractor crises, intermittency, supertransients, and non-unique dynamics (meaning that several attractors coexist). The
Understanding the factors that contribute to the formation of population genetic structure is a central goal of phylogeographic research, but achieving this goal can be complicated by the stochastic variance inherent to genetic processes. Statistical approaches to testing phylogeographic hypotheses accommodate this stochasticity by evaluating competing models of putative historical population structure, often by simulating null distributions of the expected
Many important processes in biology occur at the molecular scale. A detailed understanding of these processes can lead to significant advances in the medical and life sciences. For example, many diseases are caused by protein aggregation or misfolding. One approach to studying these systems is to use physically-based computational simulations to model the interactions and movement of the molecules. While molecular simulations are computationally expensive, it is now possible to simulate many independent molecular dynamics trajectories in a parallel fashion by using super- or distributed- computing methods such as Folding@Home or Blue Gene. The analysis of these large, high-dimensional data sets presents new computational challenges. In this seminar, I will discuss a novel approach to analyzing large ensembles of molecular dynamics trajectories to generate a compact model of the dynamics. This model groups conformations into discrete states and describes the dynamics as Markovian, or history-independent, transitions between the states. I will discuss why the Markovian state model (MSM) is suitable for macromolecular dynamics, and how it can be used to answer many interesting and relevant questions about the molecular system. I will also discuss many of the computational and statistical challenges in building such a model, such as how to appropriately cluster conformations, determine the statistical reliability, and efficiently design new simulations.
This paper outlines details of a method that includes uncertainty in deterministic simulations of oil and gas reservoirs. The method uses the probability distributions of reservoir and geological properties to obtain a likelihood distribution of the output variables. The Monte Carlo sampling (MCS) method is often-applied, but it is impractical for simulation studies because the number of computations becomes excessive. This paper uses an analytical thermal screening model to compare various variance-reduction methods with MCS simulations. The Latin hypercube sampling (LHS) method is then selected to conduct numerical simulations. The method allows computation of the partial correlation coefficients, which, as demonstrated, can be used to determine the sensitivity of process variables.
Network analysis is on the rise across scientific disciplines because of its ability to reveal complex, and often emergent, patterns and dynamics. Nonetheless, a growing concern in network analysis is the use of limited data for constructing networks. This concern is strikingly relevant to ecology and conservation biology, where network analysis is used to infer connectivity across landscapes. In this context, movement among patches is the crucial parameter for interpreting connectivity but because of the difficulty of collecting reliable movement data, most network analysis proceeds with only indirect information on movement across landscapes rather than using observed movement to construct networks. Statistical models developed for social networks provide promising alternatives for landscape network construction because they can leverage limited movement information to predict linkages. Using two mark-recapture datasets on individual movement and connectivity across landscapes, we test whether commonly used network constructions for interpreting connectivity can predict actual linkages and network structure, and we contrast these approaches to social network models. We find that currently applied network constructions for assessing connectivity consistently, and substantially, overpredict actual connectivity, resulting in considerable overestimation of metapopulation lifetime. Furthermore, social network models provide accurate predictions of network structure, and can do so with remarkably limited data on movement. Social network models offer a flexible and powerful way for not only understanding the factors influencing connectivity but also for providing more reliable estimates of connectivity and metapopulation persistence in the face of limited data.
Fletcher, Jr. , R. J.; Acevedo, M. A.; Reichert, B. E.; Pias, K. E.; Kitchens, W. M.
Network analysis is on the rise across scientific disciplines because of its ability to reveal complex, and often emergent, patterns and dynamics. Nonetheless, a growing concern in network analysis is the use of limited data for constructing networks. This concern is strikingly relevant to ecology and conservation biology, where network analysis is used to infer connectivity across landscapes. In this context, movement among patches is the crucial parameter for interpreting connectivity but because of the difficulty of collecting reliable movement data, most network analysis proceeds with only indirect information on movement across landscapes rather than using observed movement to construct networks. Statistical models developed for social networks provide promising alternatives for landscape network construction because they can leverage limited movement information to predict linkages. Using two mark-recapture datasets on individual movement and connectivity across landscapes, we test whether commonly used network constructions for interpreting connectivity can predict actual linkages and network structure, and we contrast these approaches to social network models. We find that currently applied network constructions for assessing connectivity consistently, and substantially, overpredict actual connectivity, resulting in considerable overestimation of metapopulation lifetime. Furthermore, social network models provide accurate predictions of network structure, and can do so with remarkably limited data on movement. Social network models offer a flexible and powerful way for not only understanding the factors influencing connectivity but also for providing more reliable estimates of connectivity and metapopulation persistence in the face of limited data. PMID:22084081
Fletcher, Robert J; Acevedo, Miguel A; Reichert, Brian E; Pias, Kyle E; Kitchens, Wiley M
The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulationmodel of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulationmodel, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulationmodel for the system.
Summary 1 We use a deterministic model to explore theoretically the ecological and evolutionary relevance of plastic changes in seed dispersal along ecological succession. Our model describes the effect of changing disturbance regime, age structure, density and inter- specific competition as the habitat matures, enabling us to seek the evolutionarily stable reaction norm for seed dispersal rate as a function
OPHELIE RONCE; STEPHANIE BRACHET; ISABELLE OLIVIERI; PIERRE-HENRI GOUYON; JEAN CLOBERT
A multimedia course in economic analysis was developed and used in conjunction with the United States Naval Academy. (See ED 043 790 and ED 043 791 for final reports of the project evaluation and development model.) This volume of the text discusses the simulation of behavioral relationships among variable elements in an economy and presents…
In this work, modeling, simulation and analysis of load following behaviour of microturbine (MT) as a Distributed Energy Resource (DER) have been performed. The system comprises a MT interconnected to the utility grid. The MT is capable of operating in both islanded and grid-connected modes. This work considers that the MT supplies power to variable general and critical loads. The
Profit in a competitive environment requires information to support efficient resource use in all endeavours including the forest and wood industry. The capacity to estimate value of a stand by modelling trees and simulating conversion along the whole value chain offers the potential to maximise efficiency, by enabling virtual trials of different production, processing and utilisation scenarios. Such a system
Modelling and simulation of gyrotrons have two interconnected aspects, namely beam formation in the electron-optical system (EOS) and beam-field interaction in the resonant cavity. In this paper we address both problems and outline the physical models and numerical techniques implemented in our problem-oriented package of computer codes. In order to illustrate our approach we present some results of numerical experiments
S. Sabchevski; T. Idehara; M. Glyavin; I. Ogawa; S. Mitsudo
Oceanographers and modelers often relate chlorophyll concentrations with phytoplankton carbon invoking a suitable C:Chla ratio. However C:Chl ratios are not constant in natural systems, thus making chlorophyll a deceptive measure of true biomass.In this paper we report on the adaptation of an algorithm for chlorophyll synthesis to a complex ecologicalmodel for the marine environment. Based on this model we have developed several simulation experiments to assess the performance of the chlorophyll synthesis and the phytoplankton photoadaptation strategy. The model was applied to three distinct settings, comprising distinctive model geometries and ambient conditions: a schematic setting corresponding to a virtual mesocosm without any transport scheme (0D), a 1D vertical open-ocean application to a 150 m deep water-column, and an application to an estuary using a 2D configuration. Conditions vary from spatially stable in the first case to a strong spatial and temporal heterogeneity in the case of the estuary. Our results fall within the range and reproduce some of the trends found in published data, supporting the idea that when conditions have strong changes of nutrient availability and light conditions, a photoacclimation mechanism becomes an essential requirement for reliable chlorophyll biomass estimates. This is particularly relevant if modelsimulations are to be used to study natural systems complemented by data retrieved from direct measurements.
Mateus, M.; Leitão, P. C.; de Pablo, H.; Neves, R.
The Agricultural Production Systems Simulator (APSIM) is a modular modelling framework that has been developed by the Agricultural Production Systems Research Unit in Australia. APSIM was developed to simulate biophysical process in farming systems, in particular where there is interest in the economic and ecological outcomes of management practice in the face of climatic risk. The paper outlines APSIM's structure
B. A. Keating; P. S. Carberry; G. L. Hammer; M. E. Probert; M. J. Robertson; D. Holzworth; N. I. Huth; J. N. G. Hargreaves; H. Meinke; Z. Hochman; G. McLean; K. Verburg; V. Snow; J. P. Dimes; M. Silburn; E. Wang; S. Brown; K. L. Bristow; S. Asseng; S. Chapman; R. L. McCown; D. M. Freebairn; C. J. Smith
Simulation and Modelling continue to play important roles underpining the computational sciences (1). In Computer Science we have a number of on-going simulation projects making use of field equation models, micro- scopic entity models and particle models to support research with Cahn- Hillard Cook (2) and Ginzburg-Landau equations, artificial agent models (predator-prey systems, battlefield simulations, robot tanks, robot soccer), planetary
Connectivity among populations and habitats is important for a wide range of ecological processes. Understanding, preserving, and restoring connectivity in complex landscapes requires connectivity models and metrics that are reliable, efficient, and process- based. We introduce a new class of ecological connectivity models based in electrical circuit theory. Although they have been applied in other disciplines, circuit-theoretic connectivity models are
BRAD H. MCRAE; BRETT G. DICKSON; TIMOTHY H. KEITT; VIRAL B. SHAH
|Industrial ecology education is being developed and delivered predominantly within the domains of engineering and management. Such an approach could prove somewhat limiting to the broader goal of developing industrial ecology as an integrated knowledge base inclusive of diverse disciplines, contributing to sustainable development. This paper…
This study presents an application of a well-calibrated integrative hydro-ecologicalmodel to examine water resources management in the upper and middle parts of the Yellow River basin, an arid and semiarid area in northwestern China. The hydro-ecologicalmodel was developed to simulate dynamic and accumulative hydrologic, ecologic, and economic variables at different spatial units. Four water management scenarios based on water use priorities, a business-as-usual scenario, an ecological scenario, an irrigation use efficiency scenario and water use scenario were designed and modeled over the period of 2011-2020 to reflect alternative water management pathways to the future. Water resource conditions were assessed in terms streamflow, actual evapotranspiration, soil water, groundwater yield, overall water yield, and derived indicator of drought index. Unit crop yield was to assess ecological production, and monetary values of crop productivity and water productivity were used to assess economic output. Scenario analysis results suggested that water stress would continue in the study region under both current water use patterns and ecological scenarios of river flow being fully satisfied.Water use scenarios would result in decreased water availability and ecosystem degradation in the long run. Improving irrigation use efficiency would be the most efficient approach in securing long-term water and food supply. The simulation results from this study provided useful information for evaluating long-term water resources management strategies, and will contribute to the knowledge of interdisciplinary modeling for water resources management in the study region.
The purpose of this talk is to give an overview of the role of modeling and simulation in Safeguards R&D and introduce you to (some of) the tools used. Some definitions are: (1) Modeling - the representation, often mathematical, of a process, concept, or operation of a system, often implemented by a computer program; (2) Simulation - the representation of the behavior or characteristics of one system through the use of another system, especially a computer program designed for the purpose; and (3) Safeguards - the timely detection of diversion of significant quantities of nuclear material. The role of modeling and simulation are: (1) Calculate amounts of material (plant modeling); (2) Calculate signatures of nuclear material etc. (source terms); and (3) Detector performance (radiation transport and detection). Plant modeling software (e.g. FACSIM) gives the flows and amount of material stored at all parts of the process. In safeguards this allow us to calculate the expected uncertainty of the mass and evaluate the expected MUF. We can determine the measurement accuracy required to achieve a certain performance.
Swinhoe, Martyn T. [Los Alamos National Laboratory
Acceleration driven instabilities of fluid mixing layers include the classical cases of Rayleigh-Taylor instability, driven by a steady acceleration and Richtmyer-Meshkov instability, driven by an impulsive acceleration. Our program starts with high resolution methods of numerical simulation of two (or more) distinct fluids, continues with analytic analysis of these solutions, and the derivation of averaged equations. A striking achievement has been the systematic agreement we obtained between simulation and experiment by using a high resolution numerical method and improved physical modeling, with surface tension. Our study is accompanies by analysis using stochastic modeling and averaged equations for the multiphase problem. We have quantified the error and uncertainty using statistical modeling methods.
In today's climate of government outsourcing and multiple stakeholder involvement in public sector management and service delivery, it is more important than ever to rethink and redesign the structure of how policy decisions are made, implemented, monitored, and adapted to new realities. The traditional command-and-control approach is now less effective because an increasing amount of responsibility to deliver public goods and services falls on networks of nongovernment agencies. Even though public administrators are seeking new decision-making models in an increasingly more complex environment, the public sector currently only sparsely utilizes Mediated Modeling (MM). There is growing evidence, however, that by employing MM and similar tools, public interest networks can be better equipped to deal with their long-term viability while maintaining the short-term needs of their clients. However, it may require a shift in organizational culture within and between organizations to achieve the desired results. This paper explores the successes and barriers to implementing MM and similar tools in the public sector and offers insights into utilizing them through a review of case studies and interdisciplinary literature. We aim to raise a broader interest in MM and similar tools among public sector administrators at various administrative levels. We focus primarily, but not exclusively, on those cases operating at the interface of ecology and socio-economic systems. PMID:20146770
van den Belt, Marjan; Kenyan, Jennifer R; Krueger, Elizabeth; Maynard, Alison; Roy, Matthew Galen; Raphael, Ian
Data assimilation, or the fusion of a mathematical model with ecological data, is rapidly expanding knowledge of ecological systems across multiple spatial and temporal scales. As the amount of ecological data available to a broader audience increases, quantitative proficiency with data assimilation tools and techniques will be an essential skill for ecological analysis in this data-rich era. We provide a data assimilation primer for the novice user by (1) reviewing data assimilation terminology and methodology, (2) showcasing a variety of data assimilation studies across the ecological, environmental, and atmospheric sciences with the aim of gaining an understanding of potential applications of data assimilation, and (3) applying data assimilation in specific ecological examples to determine the components of net ecosystem carbon uptake in a forest and also the population dynamics of the mayfly (Hexagenia limbata, Serville). The review and examples are then used to provide guiding principles to newly proficient data assimilation practitioners. PMID:21874332
Zobitz, J M; Desai, A R; Moore, D J P; Chadwick, M A
|The present study aimed to describe and evaluate a transformative, embodied, emergent learning approach to acquiring ecological literacy through higher education. A class of teacher candidates in a bachelor of education program filled out a survey, which had them rate their level of agreement with 15 items related to ecological macro-models.…
The present study aimed to describe and evaluate a transformative, embodied, emergent learning approach to acquiring ecological literacy through higher education. A class of teacher candidates in a bachelor of education program filled out a survey, which had them rate their level of agreement with 15 items related to ecological macro-models. Participants also completed self-efficacy measures pre- and postcourse. Overall,
The paper is a discussion of the ethical frame of corporate leadership. The ethical frame is a man- ager's ethical ecology. An ethical ecology is about the complex weave of moral obligations, in- tentions, actions, and consequences of doing business. This paper is a discussion of the ethical conceptual model or frame of a corporate leader. The paper looks at
This study presents an ecologicalmodel for religious education designed for Latvia that incorporates the principles and insights of ecofeminist theologians and religious educators. It is not only concerned with reclaiming women's place in the educational realm of the school through teaching religion, but with presenting a wider ecological perspective that is inclusive to women, men, and the Earth. Therefore
Genetically modified (GM) crops have become a real option in modern agriculture. They offer advantages for agricultural production, but they also raise concerns about their ecological and economic impacts. Decisions about GM crops are complex and call for decision support. This paper presents a qualitative multi-attribute model for the assessment of ecological and economic impacts at a farm-level of GM
Marko Bohanec; Antoine Messéan; Sara Scatasta; Frédérique Angevin; Bryan Griffiths; Paul Henning Krogh; Martin Žnidarši?; Sašo Džeroski
This paper tests the hypothesis that systems at the edge of chaos have the highest level of (thermodynamic) information, which supports the hypothesis that systems at the edge of the chaos can coordinate the most complex behavior. This is examined by the use of a realistic ecological lake model describing how an ecological system behaves (i.e. chaotic or ordered), and
In this paper, on the basis of the theories and methods of ecology and ordinary differential equation, an ecologicalmodel with an impulsive control strategy is established. By using the theories of impulsive equation, small amplitude perturbation skills and comparison technique, we get the condition which guarantees the global asymptotical stability of the lowest-level prey and mid-level predator eradication periodic
Rapid growth in land use has caused problems such as waste of natural resources, geological disasters and damage to heritage through the social, economic and environmental impacts of urban sprawl. In this paper, a new model and index system of urban ecological risk assessment (ERA) based on geographic information system (GIS) was built. To identify and classify urban ecological risk
Ecological niche models (ENMs) provide a means of characterizing the spatial distribution of suitable conditions for species, and have recently been applied to the challenge of locating potential distributional areas at the Last Glacial Maximum (LGM) when unfavorable climate conditions led to range contractions and fragmentation. Here, we compare and contrast ENM-based reconstructions of LGM refugial locations with those resulting from the more traditional molecular genetic and phylogeographic predictions. We examined 20 North American terrestrial vertebrate species from different regions and with different range sizes for which refugia have been identified based on phylogeographic analyses, using ENM tools to make parallel predictions. We then assessed the correspondence between the two approaches based on spatial overlap and areal extent of the predicted refugia. In 14 of the 20 species, the predictions from ENM and predictions based on phylogeographic studies were significantly spatially correlated, suggesting that the two approaches to development of refugial maps are converging on a similar result. Our results confirm that ENM scenario exploration can provide a useful complement to molecular studies, offering a less subjective, spatially explicit hypothesis of past geographic patterns of distribution.
Waltari, Eric; Hijmans, Robert J.; Peterson, A. Townsend; Nyari, Arpad S.; Perkins, Susan L.; Guralnick, Robert P.
Hydropower operations at Flaming Gorge Dam on the Green River in Utah, US, can produce rapid downstream changes in flow and stage during a day. These changes can, in turn, affect ecological resources below the dam, including riparian vegetation, trout, and endangered fish. Four hydropower operational scenarios featuring varying degrees of hydropower-induced flow fluctuation were evaluated with hydrologic models and multispectral aerial videography of the river. Year-round high fluctuations would support the least amount of stable spawning habitat for trout and nursery habitat for endangered fish, and would have the greatest potential for reducing growth and over winter survival of fish. Seasonally, adjusted moderate fluctuation and seasonally adjusted steady flow scenarios could increase food production and over winter survival and would provide the greatest amount of spawning and nursery habitat for fish. The year-round high fluctuation, seasonally adjusted high fluctuation, and seasonally adjusted moderate fluctuation scenarios would result in a 5% decrease in upper riparian zone habitat. the seasonally adjusted steady flow scenario would result in an 8% increase in upper riparian zone habitat. Lower riparian zone habitat would increase by about 17% for year-round and seasonally adjusted high fluctuating flow scenarios but decrease by about 24% and 69% for seasonally adjusted moderate fluctuating and steady flow scenarios, respectively.
Yin, S.C.L.; LaGory, K.E.; Hayse, J.W.; Hlohowskyj, I.; Van Lonkhuyzen, R.A.; Cho, H.E. [Argonne National Lab., IL (United States). Environmental Assessment Div.
Stable isotopes are increasingly being used as tracers in ecological studies. One application uses isotopic ratios to quantify the proportional contributions of multiple sources to a mixture. Examples include food sources for animals, water sources for plants, pollution sources...
Aquatic ecological populations and communities are affected by the nature and quality of the water in which they live. Specific factors that affect instream biota include chemical variables, biotic interactions, energy source, flow regime, and habitat structure. As watershed mana...
Network centric warfare (NCW) need to be supported by modeling and simulation systems, and the interoperability between different simulation systems is an important aspect to realize cooperation of varied military simulation systems and establish common simulation environment. However, complexities of the NCW and individual military simulation systems make the interoperability difficult to achieve. A large body of work shows that
Three Legionella pneumophila strains isolated from water samples and belonging to serogroups (sgs) 1, 6 and 9 were analysed for their capacity to colonise an experimental modelsimulating a domestic hot water distribution system. Ecological factors that could influence the persistence of the sgs such as intracellular life within protozoan hosts and bacterial interference by the production of antagonistic compounds were also studied. Viable counts of L. pneumophila increased both in the planktonic and in the sessile phases. Sg 6 showed a marked prevalence during the whole experiment and exhibited the highest host infection efficiency. Sg 1 was significantly less represented, but showed the highest capacity to reproduce in the protozoan hosts. Sg 9 was poorly represented and less adapted to intracellular life. Among the 14 bacteria constantly isolated in the system, five (35.7%) produced antagonistic substances against Legionella, with differences according to the bacterial strain and L. pneumophila sgs. PMID:21240698
Messi, P; Anacarso, I; Bargellini, A; Bondi, M; Marchesi, I; de Niederhäusern, S; Borella, P
Component-based modeling introduces an alternative approach for simulating watershed systems where a model can be composed of components from different disciplines, interlinked through shared boundary conditions. One advantage of component-based modeling is that it allows components to be created, tested, and maintained by independent groups, while still remaining compliant within a larger modeling system. By providing a basic framework in which components can be interlinked, watershed models can evolve more dynamically because groups are able to specialize in parts of the overall system. Despite these advantages of component-based modeling of watershed systems, there are also challenges. This paper addresses the metadata requirements for guiding development of a component-based watershed model so that different representations of the same process can be easily exchanged. We address this challenge by considering how two widely used watershed modeling systems, the Regional Hydro-EcologicSimulation System (RHESSys) and the Soil and Water Assessment Tool (SWAT), can be decomposed into components. We then implement prototype components from these models using the Open Modeling Interface (OpenMI) and test how different component configurations can be assembled to simulate rainfall/runoff processes using the Coweeta Hydrologic Laboratory as our study area. The result of this work is proposed metadata requirements for the organization of a component-based watershed modeling system, focusing in particular on the classification of model components and the structure required to enable plug-and-play of model components.
PROMODEL's simulationmodeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel® is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, InnovateTM, and ProModel PITM (for process
We developed a mathematical model with two-way linked socio-ecological dynamics to study farmland abandonment and to understand\\u000a the regimes shifts of this socio-ecological system. The model considers that migration is a collective behavior socio-economically\\u000a driven and that the ecosystem is dynamic. The model identifies equilibria that vary from mass migration, farmland abandonment,\\u000a and forest regeneration, to no migration and forest
Many types of ecological or environmental problems would benefit from models based on people’s knowledge. To create ecologicalmodels with both expert and local people’s knowledge, a multi-step fuzzy cognitive mapping approach is proposed. A cognitive map can be made of almost any system or problem. Cognitive maps are qualitative models of a system, consisting of variables and the causal
This paper presents an agent-based, object-oriented ecologicalmodel of forest dynamics designed to examine the role of disturbance on diversity. Arborscapes is based on Swarm, an agent-based software platform that offers advantages for ecologicalmodeling, including a suite of standardized libraries of objects, schedules, and probes, and architectural features such as inheritance, message passing, encapsulation, and hierarchical structure. Object-oriented models
We propose two nutrient-phytoplankton models with instantaneous and time delayed recycling, investigate the dynamics and examine the responses to model complexities. Instead of the familiar specific uptake rate and growth rate functions, we assume only that the nutrient uptake and phytoplankton growth rate functions are positive, increasing and bounded above. We use geometrical and analytical methods to find conditions for the existence of none, one, or at most two positive steady states and analyze the stability properties of each of these equilibria. With the variation of parameters, the system may lose its stability and bifurcation may occur. We study the occurrence of Hopf bifurcation and the possibility of stability switching. Numerical simulations illustrate the analytical results and provide further insight into the dynamics of the models, biological interpretations are given.
Many real ecological systems show sudden changes in behavior, phenomena sometimes categorized as regime shifts in the literature. The relative importance of exogenous versus endogenous forces producing regime shifts is an important question. These forces' role in generating variability over time in ecological systems has been explored using tools from dynamical systems. We use similar ideas to look at transients in simple ecologicalmodels as a way of understanding regime shifts. Based in part on the theory of crises, we carefully analyze a simple two patch spatial model and begin to understand from a mathematical point of view what produces transient behavior in ecological systems. In particular, since the tools are essentially qualitative, we are able to suggest that transient behavior should be ubiquitous in systems with overcompensatory local dynamics, and thus should be typical of many ecological systems. PMID:18066628
The motivation for the Model-based Integrated Simulation (MILAN) project is to develop an extensible modeling, simulation, and design space exploration framework for the design of latency and energy efficient embedded systems for signal processing applica...
In Alpine areas, the temporal patterns of hydropower plants operations can have consequences for the water bodies which receive downstream releases in the form of "hydropeaking", typically consisting in sharp releases of turbinated water in the river reaches below dams. Hydropeaking may significantly affect also the thermal regime of rivers: typically power plants fed by hypolimnetic releases from large dams cause a reduction in summer temperature and an increase in winter temperatures for long distances downstream. Very few studies have addressed the effects of the short-term temperature fluctuations related to hydropeaking (i.e., thermopeaking) on aquatic fauna, although they can be a major cause of riverine habitat degradation posing serious threats to aquatic communities. In the Adige River watershed, warm thermopeaking occurs from September to January and results in additional (up to 4°C) heating to the natural dial fluctuations; cold thermopeaking occurs from March to July and cools down the temperature (up to 6°C), in contrast with the natural trend that would result in heating during the day. The biological effects of thermopeaking are difficult to study in nature, because they are associated with hydropeaking, which is known to cause a high catastrophic drift due to the increased intensity of bed scour. However, controlled simulations of thermopeaking events could be performed in artificial flumes. We used artificial flumes which had proved to perform discharge manipulations which simulate hydropeaking events, and conducted four simulations, two warm thermopeakings in early and late winter, and two cold-thermopeakings, in early and late summer, respectively. The impact of thermopeaking on benthic macroinvertebrates was assessed by collecting those organisms which are displaced from the substrate and drift in the water column. Displacement can be active (i.e., part of the behavioural repertoire of certain insect species), or passive (i.e., catastrophic and generated by any disturbance). Drifting invertebrates were collected at time intervals before the simulation, and at continuous, short-time intervals during the simulation in order to follow the changes in drift over a short time period during the simulation. We assessed the effects of thermopreaking on the benthos community by answering to the following questions: 1) Do thermal alterations induce an increase in drift of benthic invertebrates? 3) Do a reduction or an increase in water temperature have different effects of invertebrate drift? Benthic invertebrates responded more to the cold thermopeaking simulations, with differences among taxa with different life strategies and ecological requirements.
Maiolini, Bruno; Carolli, Mauro; Bruno, M. Cristina; Siviglia, Annunziato
With the exponential growth in the power of computing hardware and software, modeling and simulation is becoming a key enabler for the rapid design of reliable Microsystems. One vision of the future microsystem design process would include the following primary software capabilities: (1) The development of 3D part design, through standard CAD packages, with automatic design rule checks that guarantee the manufacturability and performance of the microsystem. (2) Automatic mesh generation, for 3D parts as manufactured, that permits computational simulation of the process steps, and the performance and reliability analysis for the final microsystem. (3) Computer generated 2D layouts for process steps that utilize detailed process models to generate the layout and process parameter recipe required to achieve the desired 3D part. (4) Science-based computational tools that can simulate the process physics, and the coupled thermal, fluid, structural, solid mechanics, electromagnetic and material response governing the performance and reliability of the microsystem. (5) Visualization software that permits the rapid visualization of 3D parts including cross-sectional maps, performance and reliability analysis results, and process simulation results. In addition to these desired software capabilities, a desired computing infrastructure would include massively parallel computers that enable rapid high-fidelity analysis, coupled with networked compute servers that permit computing at a distance. We now discuss the individual computational components that are required to achieve this vision. There are three primary areas of focus: design capabilities, science-based capabilities and computing infrastructure. Within each of these areas, there are several key capability requirements.
Quantum computation simulation has been a hot research topic recently and a few softwares used in research have been developed. Compared with these existed softwares and their approaches, this paper proposes an object oriented quantum cryptography simulationmodel. Furthermore, we also firstly integrate classical cryptography algorithms into this model. Finally, the advantages and disadvantages of this model over other simulation
This paper presents a knowledge based modeling system that allows a manufacturing engineer who has very limited knowledge of simulation methodology to quickly and correctly, develop and run a simulationmodel of an automated guided vehicle system (AGVS). The modeling system is capable of guiding and assisting the engineer with a level of “expertise” comparable to a trained simulation specialist.
The PERPEST model is a model that predicts the ecological risks of pesticides in freshwater ecosystems. This model simultaneously predicts the effects of a particular concentration of a pesticide on various (community) endpoints. In contrast to most effect models, PERPEST is based on empirical data extracted from the literature. This model is based on case-based reasoning, a technique that solves
Brink van den P. J; Jan Roelsma; Nes van E. H; Marten Scheffer; Theo C. M. Brock
In Europe, the Water Framework Directive (WFD) is providing a powerful regulatory driver to adopt integrated catchment management, and so pressurizing researchers to build suitable supporting tools. The WFD requires agencies to drive towards `good ecological quality' by 2015. After the initial step of characterising water bodies and the pressures on them, the next substantive step is the preparation of river basin management plans and proposed programmes of measures by 2009. Ecological quality is a complex concept and poorly defined, unless it is taken as a simple measure such as the abundance of a particular species of organism. There is clearly substantial work to do to build a practical but sound definition of ecological quality; practical in the sense of being easy to measure and explain to stakeholders, and sound in the sense that it reflects ecological complexity within catchments, the variability between catchments, and the conflicts demands for goods and services that human society places upon the ecological system. However ecological quality is defined, it will be driven by four interacting groups of factors. These represent the physical, chemical, ecological and socio-economic environments within and encompassing the catchment. Some of these groupings are better understood than others, for example hydrological processes and the transport of solutes are reasonably understood, even though they remain research areas in their own right. There are much larger gaps in our understanding at the interfaces, i.e. predicting how, for example, hydrological processes such as flow and river morphology influence ecological quality. Overall, it is clear we are not yet in a position to build deterministic models of the overall ecological behaviour of catchment. But we need predictive tools to support catchment management agencies in preparing robust plans. This poster describes our current exploration of soft modelling options to build a comprehensive macro-ecologicalmodel of UK catchments. This is taking place within the Catchment Science Centre, a joint venture between the University of Sheffield and the Environment Agency.
Lerner, R. N.; Lerner, D. N.; Surridge, B.; Paetzold, A.; Harris, B.; Anderson, C. W.
The ecological traits and functional capabilities of marine animals have changed significantly since their origin in the late Precambrian. These changes can be analysed quantitatively using multi-dimensional parameter spaces in which the ecological lifestyles of species are represented by particular combinations of parameter values. Here, we present models that describe the filling of this multi-dimensional ‘ecospace’ by ecological lifestyles during metazoan diversification. These models reflect varying assumptions about the processes that drove ecological diversification; they contrast diffusive expansion with driven expansion and niche conservatism with niche partitioning. Some models highlight the importance of interactions among organisms (ecosystem engineering and predator–prey escalation) in promoting new lifestyles or eliminating existing ones. These models reflect processes that were not mutually exclusive; rigorous analyses will continue to reveal their applicability to episodes in metazoan history.
A model waste based on a modest vegetarian diet is given, including composition and elemental analysis. Its use is recommended for evaluation of candidate waste treatment processes for a Controlled Ecological Life Support System (CELSS).
? Traditional approaches to ecologicalmodeling, based on mathematical equations, are hampered by the qualitative nature of ecological knowledge. In this article, we demonstrate that qualitative rea- soning provides alternative and productive ways for ecologists to develop, organize, and implement models. We present a qualitative theory of popula- tion dynamics and use this theory to capture and simulate commonsense theories
In this paper, models are described which have been developed to model both the way in which a population of cells respond to radiation and the way in which a population of patients respond to radiotherapy to assist the conduct of clinical trials in silico. Population balance techniques have been used to simulate the age distribution of tumour cells in the cell cycle. Sensitivity to radiation is not constant round the cell cycle and a single fraction of radiation changes the age distribution. Careful timing of further fractions of radiation can be used to maximize the damage delivered to the tumour while minimizing damage to normal tissue. However, tumour modelling does not necessarily predict patient outcome. A separate model has been established to predict the course of a brain cancer called glioblastoma multiforme (GBM). The model considers the growth of the tumour and its effect on the normal brain. A simple representation is included of the health status of the patient and hence the type of treatment offered. It is concluded that although these and similar models have a long way yet to be developed, they are beginning to have an impact on the development of clinical practice.
Models are required that permit the estimation of emitted field signatures from EMP simulators to design the simulator antenna structure, to establish the usable test volumes, and to estimate human exposure risk. This paper presents the capabilities and limitations of a variety of EMP simulatormodels useful to the Army's EMP survivability programs. Comparisons among frequency and time-domain models are provided for two powerful US Army Research Laboratory EMP simulators: AESOP (Army EMP Simulator Operations) and VEMPS II (Vertical EMP Simulator II).
Species reintroduction programmes, in prior- itizing areas for reintroductions, have traditionally used tools that include measures of habitat suitability and evaluations of area requirements for viable populations. Here we add two tools to this approach: evaluation of ecological requirements of species and evaluation of future suitability for species facing changing climates. We demonstrate this approach with two species for which
Enrique Martínez-Meyer; A. Townsend Peterson; Jorge I. Servín; Lloyd F. Kiff
Mangroves are coastal halophytes that tend to inhabit the low energy, tropical and sub-tropical coasts of the world. The mangrove habitats that occupy large swaths of the south Florida coastline are important habitats for a myriad of ecological and economic reasons. As such, the Florida legislature enacted the mangrove preservation act of 1996 to ensure the protection and proper trimming
Many analyses of ecological networks in recent years have introduced new indices to describe network properties. As a consequence, tens of indices are available to address similar questions, differing in specific detail, sensitivity in detecting the property in question, and robustness with respect to network size and sampling intensity. Furthermore, some indices merely reflect the number of species participating in
Carsten F. Dormann; Jochen Frund; Nico Bluthgen; Bernd Gruber
This book is a synthesis of what has been learned about ecological succession from the process of developing the models for the various systems which typically consisted of starting with the FORET model (an Appalachian deciduous forest). Modifying, testing, and applying such a model is the core of this work. Contents, abridged: Forest succession. Computer models of forest succession. Patch
Modelling an ecosystem requires knowledge of the system, obtained with experiments, and its abstraction within a mathematical framework. Systems methods can be used effectively in the latter phase of the modelling process. Indeed, when coupled with experimental work, these mathematical methods can help in the development of an ecologically realistic mathematical model. These models formalize hypotheses proposed to describe the
Background Bacillus anthracis, the causative agent of anthrax, is a globally distributed zoonotic pathogen that continues to be a veterinary and human health problem in Central Asia. We used a database of anthrax outbreak locations in Kazakhstan and a subset of genotyped isolates to model the geographic distribution and ecological associations of B. anthracis in Kazakhstan. The aims of the study were to test the influence of soil variables on a previous ecological niche based prediction of B. anthracis in Kazakhstan and to determine if a single sub-lineage of B. anthracis occupies a unique ecological niche. Results The addition of soil variables to the previously developed ecological niche model did not appreciably alter the limits of the predicted geographic or ecological distribution of B. anthracis in Kazakhstan. The A1.a experiment predicted the sub-lineage to be present over a larger geographic area than did the outbreak based experiment containing multiple lineages. Within the geographic area predicted to be suitable for B. anthracis by all ten best subset models, the A1.a sub-lineage was associated with a wider range of ecological tolerances than the outbreak-soil experiment. Analysis of rule types showed that logit rules predominate in the outbreak-soil experiment and range rules in the A1.a sub-lineage experiment. Random sub-setting of locality points suggests that models of B. anthracis distribution may be sensitive to sample size. Conclusions Our analysis supports careful consideration of the taxonomic resolution of data used to create ecological niche models. Further investigations into the environmental affinities of individual lineages and sub-lineages of B. anthracis will be useful in understanding the ecology of the disease at large and small scales. With model based predictions serving as approximations of disease risk, these efforts will improve the efficacy of public health interventions for anthrax prevention and control.
This paper surveys verification and validation of models, especially simulationmodels in operations research. For verification it discusses 1) general good programming practice (such as modular programming), 2) checking intermediate simulation outputs through tracing and statistical testing per module, 3) statistical testing of final simulation outputs against analytical results, and 4) animation. For validation it discusses 1) obtaining real-worl data,
The general concept of an integrated software support environment to enhance the productivity of the simulationmodeller has motivated several groups to design and implement such environments. Underlying each such development is a perspective, implicit or explicit, of the methodology of simulationmodelling. This paper rewews the experience of the Computer Aided Simulation Modellin8 (CASM)group at the London School of
Various ad hoc routing algorithms were proposed to increase the performance in ad hoc network. In order to estimate the performance of routing algorithms, they always simulate in ad hoc network environment, and a mobility model is also used for network simulation. There are two types of mobility models: trace and synthetic models. Trace models are more accurate than synthetic
Hsien-chou Liao; Yi-wei Ting; Shih-hsuan Yen; Chou-Chen Yang
Schizothorax Yunnansis is an unique fish species only existing in Lugu Lake, which is located in the southwestern China. The simulation and research on Schizothorax Yunnansis habitat environment have a vital significance to protect this rare fish. With the development of the tourism industry, there bring more pressure on the environmental protection. The living environment of Schizothorax Yunnansis is destroyed seriously because the water quality is suffering the sustaining pollution of domestic sewage from the peripheral villages. This paper analyzes the relationship between water quality change and Schizothorax Yunnansis ecological habitat and evalutes Schizothorax Yunnansis's ecological habitat impact based on HABITAT model. The results show that when the TP concentration in Lugu Lake does not exceed Schizothorax Yunnansis's survival threshold, Schizothorax Yunnansis can get more nutrients and the suitable habitat area for itself is increased. Conversely, it can lead to TP toxicity in the Schizothorax Yunnansis and even death. Therefore, unsuitable habitat area for Schizothorax Yunnansis is increased. It can be seen from the results that HABITAT model can assist in ecological impact assessment studies by translating results of hydrological, water quality models into effects on the natural environment and human society.
An ecological process model (BIOME-BGC) was used to assess boreal forest regional net primary production (NPP) and response to short-term, year-to-year weather fluctuations based on spatially explicit, land cover and biomass maps derived by radar remote sensing, as well as soil, terrain and daily weather information. Simulations were conducted at a 30-m spatial resolution, over a 1205 km(2) portion of the BOREAS Southern Study Area of central Saskatchewan, Canada, over a 3-year period (1994-1996). Simulations of NPP for the study region were spatially and temporally complex, averaging 2.2 (+/- 0.6), 1.8 (+/- 0.5) and 1.7 (+/- 0.5) Mg C ha(-1) year(-1) for 1994, 1995 and 1996, respectively. Spatial variability of NPP was strongly controlled by the amount of aboveground biomass, particularly photosynthetic leaf area, whereas biophysical differences between broadleaf deciduous and evergreen coniferous vegetation were of secondary importance. Simulations of NPP were strongly sensitive to year-to-year variations in seasonal weather patterns, which influenced the timing of spring thaw and deciduous bud-burst. Reductions in annual NPP of approximately 17 and 22% for 1995 and 1996, respectively, were attributed to 3- and 5-week delays in spring thaw relative to 1994. Boreal forest stands with greater proportions of deciduous vegetation were more sensitive to the timing of spring thaw than evergreen coniferous stands. Similar relationships were found by comparing simulated snow depth records with 10-year records of aboveground NPP measurements obtained from biomass harvest plots within the BOREAS region. These results highlight the importance of sub-grid scale land cover complexity in controlling boreal forest regional productivity, the dynamic response of the biome to short-term interannual climate variations, and the potential implications of climate change and other large-scale disturbances. PMID:12651512
Kimball, J. S.; Keyser, A. R.; Running, S. W.; Saatchi, S. S.
The Interactive Communication System SimulationModel (ICSSM), developed for the Rome Air Development Center, is capable of simulating a point-to-point communication system including its functional elements, components, propagation effects, and transmissi...
Campylobacteriosis, like many human diseases, has its own ecology in which the propagation of human infection and disease depends on pathogen survival and finding new hosts in order to replicate and sustain the pathogen population. The complexity of this process, a process common to other enteric pathogens, has hampered control efforts. Many unknowns remain, resulting in a poorly understood disease ecology. To provide structure to these unknowns and help direct further research and intervention, we propose an eco-environmental modeling approach for campylobacteriosis. This modeling approach follows the pathogen population as it moves through the environments that define the physical structure of its ecology. In this paper, we term the ecologic processes and environments through which these populations move "pathogen survival trajectories." Although such a modeling approach could have veterinary applications, our emphasis is on human campylobacteriosis and focuses on human exposures to Campylobacter through feces, food, and aquatic environments. The pathogen survival trajectories that lead to human exposure include ecologic filters that limit population size, e.g., cooking food to kill Campylobacter. Environmental factors that influence the size of the pathogen reservoirs include temperature, nutrient availability, and moisture availability during the period of time the pathogen population is moving through the environment between infected and susceptible hosts. We anticipate that the modeling approach proposed here will work symbiotically with traditional epidemiologic and microbiologic research to help guide and evaluate the acquisition of new knowledge about the ecology, eventual intervention, and control of campylobacteriosis.
This investigation presents the analysis of a model of teaching science called the Conceptual Change Model. This model stimulates students to identify their own and alternate science concepts, and to confront these concepts with dynamic situations that will incite a conceptual change and promote their ability to master and understand the conceptual systems that serve as foundations for scientific knowledge. During a previous research made by this investigator on the Conceptual Change Model, a proposal for a new teaching model came up which she called the Productive Ecological Koinos Model. This model incorporates, among other things, the teacher's reflection and inner thoughts about the concepts taught and the learning experiences achieved in concurrence with students. Using action research, an exploration and analysis was done that focused upon how students and teachers modified their perspective of science while testing the Productive Ecological Koinos Model during the teaching-learning processes that took place in a microbiology course. The action research design allows the researcher to analyze these points from the experiential perspective, while also allowing the researcher to participate in the study. The study employed qualitative research techniques such as reflective diaries, personal profiles of participants, document analysis, audio tape recordings and transcriptions. All of these techniques are accepted within action research (Elliot, 1991). The Wolcott Model was the data analysis method used in the research. The description, analysis and interpretation carried out allowed for the examination of the various components of the Productive Ecological Koinos Model with students and teachers as to the scientific terms virus and contagion, and their experiences during the learning process within and outside the classroom. From the analysis of the Model a modification cropped up which places emphasis on conscious introspection on the learning process. This new learning model has been named the Cognitive Reflection Model. Through this Model, an analysis and introspection is made on the cognitive foundations of the scientific concept from the perspectives of the experiences of both teachers and students. It proposes, among other things, scrutiny into what could be called "Reflexive Science" for the teaching of science subjects as a result of using the Cognitive Reflection Model.
The eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important in the global cycling of nitrogen. These organisms are unique in their ability to use the conversion of ammonia to
\\u000a The theory of evolution has recently been in turmoil, with great interest in applying empirical information from EvoDevo,\\u000a genomics, and ecology into the framework of quantitative genetic studies of evolution. Ciona is a small genus of sea squirts within the class Ascidiacea of the subphylum Tunicata, the sister group of vertebrates, a\\u000a phylogenetic position that has contributed to fuel the
Gabriele Procaccini; Ornella Affinito; Francesco Toscano; Paolo Sordino
\\u000a Conservation practitioners and resource managers must often work with limited data to answer critical, time-sensitive questions.\\u000a In many regions of the world, even the most basic information about the distribution of species is lacking. Knowing the geographic\\u000a extent of a given species or ecological system is the first step in planning for its management or conservation. The sustainable\\u000a management of
Josh J. Lawler; Yolanda F. Wiersma; Falk Huettmann
\\u000a Defining an appropriate role for expert knowledge in science can lead to contentious debate. The professional experience of\\u000a ecologists, elicited as expert judgment, plays an essential role in many aspects of landscape ecological science. Experts\\u000a may be asked to judge the relevance of competing research or management questions, the quality and suitability of available\\u000a data, the best balance of complexity
We argue that two styles of explanation—mechanistic and ecological—are needed in accounting for the behaviour of synthetic agents. An emphasis on mechanistic explanation in some current ALife models is identified, and parallels are drawn with issues in the philosophy of mind literature. We conclude that ecological or agent-level explanation does not come with representational baggage, and that mechanistic ex- planations
Ecological studies enable investigation of geographic variations in exposure to environmental variables, across groups, in\\u000a relation to health outcomes measured on a geographic scale. Such studies are subject to ecological biases, including pure\\u000a specification bias which arises when a nonlinear individual exposure-risk model is assumed to apply at the area level. Introduction\\u000a of the within-area variance of exposure should induce
Using a variant of the ecological-transactional model and developmental theories of delinquency on a nationally representative\\u000a sample of adolescents, the current study explored the ecological predictors of violent victimization, perpetration, and both\\u000a for three different developmental stages during adolescence. We examined the relative influence of individual and family characteristics,\\u000a peers, and neighborhood characteristics on the odds of experiencing violent victimization
Jennifer L. MatjaskoBelinda; Belinda L. Needham; Leslie N. GrundenAmy; Amy Feldman Farb
The measurement error model is a well established statistical method for regression problems in medical sciences, although\\u000a rarely used in ecological studies. While the situations in which it is appropriate may be less common in ecology, there are\\u000a instances in which there may be benefits in its use for prediction and estimation of parameters of interest. We have chosen\\u000a to
Robert J. Denham; Matthew G. Falk; Kerrie L. Mengersen
A simulationmodel for electrical discharges which is capable of modeling streamer and leader propagation over long distances is described. The model couples an electrostatic field solver, a chemistry package, and a package for solving the hydrodynamic eq...
D. F. Gordon P. Sprangle S. Slinker R. Fernsler M. Lampe
Saarenmaa, H., Stone, N.D., Folse, L.J., Packard, J.M., Grant, W.E., Makela, M.E. and Coulson, R.N., 1988. An artificial intelligence modelling approach to simulating animal\\/habitat interactions. Ecol. Modelling, 44: 125-141. Ecologicalmodellers have begun to recognize the potential of object-oriented program- ming techniques in structuring models. However, little has been done to take advantage of artificial intelligence's (AI) symbolic representations to
H. SAARENMAA; N. D. STONE; L. J. FOLSE; J. M. PACKARD; W. E. GRANT; M. E. MAKELA; R. N. COULSON
The National Hydrography and updated Watershed Boundary Datasets provide a ready-made framework for hydrographic modeling. Determining particular stream reaches or watersheds in poor ecological condition across large regions is an essential goal for monitoring and management. T...
Further development of process-based spatial models is needed to facilitate explanation in landscape ecology. We discuss the dual modeling goals of prediction and explanation and identify challenges faced in explaining landscape patterns. These challenges are especially acute in attempts to explain patterns that result from complex adaptive systems. We compare examples of two process models used to describe landscape changes
Daniel G. Brown; Richard Aspinall; David A. Bennett
This study uses structural equation modeling to investigate several predictors of hospital system satisfaction. Drawing on Street's ecological perspective, the researchers explore several individual, provider–patient interaction, and system perceptions and expectations, test a model of hospital system satisfaction, and discuss the implications of the structural equation modeling analysis. Specifically, it was hypothesized that individuals who rated themselves as having high
Scott D. Moore; Kevin B. Wright; Daniel R. Bernard
|The incorporation of mathematical modeling experiences into an undergraduate biology course is described. Detailed expositions of three models used to teach concepts of population ecology are presented, including introductions to major concepts, user instructions, trial data and problem sets. The models described are: 1) an exponential/logistic…
Community psychology (CP) research on the natural environment lacks a theoretical framework for analyzing the complex relationship between human systems and the natural world. We introduce other academic fields concerned with the interactions between humans and the natural environment, including environmental sociology and coupled human and natural systems. To demonstrate how the natural environment can be included within CP's ecological framework, we propose an ecologicalmodel of urban forest stewardship action. Although ecologicalmodels of behavior in CP have previously modeled health behaviors, we argue that these frameworks are also applicable to actions that positively influence the natural environment. We chose the environmental action of urban forest stewardship because cities across the United States are planting millions of trees and increased citizen participation in urban tree planting and stewardship will be needed to sustain the benefits provided by urban trees. We used the framework of an ecologicalmodel of behavior to illustrate multiple levels of factors that may promote or hinder involvement in urban forest stewardship actions. The implications of our model for the development of multi-level ecological interventions to foster stewardship actions are discussed, as well as directions for future research to further test and refine the model. PMID:22722897
This paper presents a product development process modeling and analysis technique using advanced simulation. The model computes the probability distribution of lead time in a resource -constrained project network where iterations take place among sequential, parallel and overlapped tasks. The model uses the design structure matrix representation to capture the information flows between tasks. In each simulation run, the expected
Since its release in 1993, MedModel has continued to make substantial strides in the evolution of healthcare simulation software. Until its arrival, the complex interdependencies and extreme number of variable outcomes exhibited by the ordinary healthcare system restricted the use of simulation to large forecasting or trend analysis models. MedModel was specifically designed to be simple to use and tailorable
Since its release in 1993, MedModel has continued to make substantial strides in the evolution of healthcare simulation software. Until its arrival, the complex interdependencies and extreme number of variable outcomes exhibited by the ordinary healthcare system restricted the use of simulation to large forecasting or trend analysis models. MedModel was specifically designed to be simple to use and tailorable
This research develops a data-integrated approach for constructing simulationmodels based on a real data set provided by Baylor Regional Medical Center (Baylor) in Grapevine, Texas. Tree-based models and kernel density estimation were utilized to extract important knowledge from the data for the simulation. Classification and Regression Tree model, a data mining tool for prediction and classification, was used to
Durai Sundaramoorthi; Victoria C. P. Chen; Seoung B. Kim; Jay M. Rosenberger; Deborah F. Buckley-Behan
Coupled atmospheric-biospheric models are a particularly valuable tool for studying the potential effects of land-use and land-cover changes on the near-surface atmosphere since the atmosphere and biosphere are allowed to dynamically interact through the surface and canopy energy balance. GEMRAMS is a coupled atmospheric-biospheric model comprised of an atmospheric model, RAMS, and an ecophysiological process-based model, GEMTM. In the first part of this study, the soil-vegetation-atmosphere-transfer (SVAT) scheme, LEAF2, from RAMS, coupled with GEMTM, are used to simulate energy, water and carbon fluxes over different cropping systems (winter wheat and irrigated corn) and over a mixed C3/C4 shortgrass prairie located at the USDA-ARS Central Plains Experimental Range near Nunn, Colorado, the LTER Shortgrass Steppe site. The new SVAT scheme, GEMLEAF, is forced with air temperature and humidity, wind speed and photosynthetic active radiation (PAR). Calculated canopy temperature and relative humidity, soil moisture and temperature and PAR are used to compute sunlit/shaded leaf photosynthesis (for C3 and C4 plant types) and respiration. Photosynthate is allocated to leaves, shoots, roots and reproductive organs with variable partition coefficients, which are functions of soil water conditions. As water stress increases, the fraction of photosynthate allocated to root growth increases. Leaf area index (LAI) is estimated from daily leaf biomass growth, using the vegetation-prescribed specific leaf area. Canopy conductance, computed and based on photosynthesis and relative humidity, is used to calculate latent heat flux. Simulated energy and CO2 fluxes are compared to observations collected using Bowen ratio flux towers during two growing seasons. Seasonality of the fluxes reflecting different plant phenologies agrees well with the observed patterns. In the second part of this study, simulations for two clear days are performed with GEMRAMS over a model domain centered at the SGS site. Simulated spatial differences in the energy fluxes can be associated with the highly heterogeneous landscape in this area.
Beltran-Przekurat, A. B.; Pielke, R. A.; Morgan, J. A.; Burke, I. C.
A survey was conducted to evaluate the current state of the art and technology of model/simulation capabilities at Rome Air Development Center, Griffiss AFB, NY. This memo presents a tabulation of 28 such models/simulations. These models/simulations are being used within RADC in the development and evaluations of Command, Control, Communications and Intelligence (C3I) technology. The results of this survey are incorporated in this memo.
Adélie penguins ( Pygoscelis adeliae), carabeater seals ( Lobodon carcinophagus), humpback ( Megaptera novaeangliae), and minke whales ( Balaenoptera bonaernsis) are found in the waters surrounding the Western Antarctic Peninsula. Each species relies primarily on Antarctic krill ( Euphausia superba) and has physiological constraints and foraging behaviors that dictate their ecological niches. Understanding the degree of ecological overlap between sympatric krill predators is critical to understanding and predicting the impacts on climate-driven changes to the Antarctic marine ecosystem. To explore ecological relationships amongst sympatric krill predators, we developed ecological niche models using a maximum entropy modeling approach (Maxent) that allows the integration of data collected by a variety of means (e.g. satellite-based locations and visual observations). We created spatially explicit probability distributions for the four krill predators in fall 2001 and 2002 in conjunction with a suite of environmental variables. We find areas within Marguerite Bay with high krill predator occurrence rates or biological hot spots. We find the modeledecological niches for Adélie penguins and crabeater seals may be affected by their physiological needs to haul-out on substrate. Thus, their distributions may be less dictated by proximity to prey and more so by physical features that over time provide adequate access to prey. Humpback and minke whales, being fully marine and having greater energetic demands, occupy ecological niches more directly proximate to prey. We also find evidence to suggest that the amount of overlap between modeled niches is relatively low, even for species with similar energetic requirements. In a rapidly changing and variable environment, our modeling work shows little indication that krill predators maintain similar ecological niches across years around Marguerite Bay. Given the amount of variability in the marine environment around the Antarctic Peninsula and how this affects the local abundance of prey, there may be consequences for krill predators with historically little niche overlap to increase the potential for interspecific competition for shared prey resources.
Friedlaender, Ari S.; Johnston, David W.; Fraser, William R.; Burns, Jennifer; Halpin, Patrick N.; Costa, Daniel P.
The paper discusses verification, validation, and accreditation of simulationmodels. The different approaches to deciding model validity are presented; how model verification and validation relate to the model development process are discussed; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are described; ways to document results are given; a recommended procedure is presented;
The recent public health reawakening to the role of the built environment has largely excluded consideration of the natural environment. This exclusion is despite the fact that land conservation, or green infrastructure, supports the most fundamental human needs and healthy lifestyles. Although the contemporary public health paradigm acknowledges the environment as an important construct in an "ecological" approach to health, environmental protection is not commonly viewed as an upstream approach to preventing disease. This guest commentary suggests that environmental health research and practice should consider green infrastructure as germane to a healthy human environment. PMID:22187855
This paper discusses fundamental concepts of uncertainty analysis relevant to both stochastic simulationmodels and deterministic models. A stochastic simulationmodel, called a simulationmodel, is a stochastic mathematical model that incorporates random numbers in the calculation of the model prediction. Queuing models are familiar simulationmodels in which random numbers are used for sampling interarrival and service times. Another example of simulationmodels is found in probabilistic risk assessments where atmospheric dispersion submodels are used to calculate movement of material. For these models, randomness comes not from the sampling of times but from the sampling of weather conditions, which are described by a frequency distribution of atmospheric variables like wind speed and direction as a function of height above ground. A common characteristic of simulationmodels is that single predictions, based on one interarrival time or one weather condition, for example, are not nearly as informative as the probability distribution of possible predictions induced by sampling the simulation variables like time and weather condition. The language of model analysis is often general and vague, with terms having mostly intuitive meaning. The definition and motivations for some of the commonly used terms and phrases offered in this paper lead to an analysis procedure based on prediction variance. In the following mathematical abstraction the authors present a setting for model analysis, relate practical objectives to mathematical terms, and show how two reasonable premises lead to a viable analysis strategy.
More than 31 million hectares of land are protected and managed in 16 refuges by the U.S. Fish and Wildlife Service (USFWS) in Alaska. The vastness and isolation of Alaskan refuges give rise to relatively intact and complete ecosystems. The potential for these lands to provide habitat for trust species is likely to be altered, however, due to global climate change, which is having dramatic effects at high latitudes. The ability of USFWS to effectively manage these lands in the future will be enhanced by a regional inventory and monitoring program that integrates and supplements monitoring currently being implemented by individual refuges. Conceptual models inform monitoring programs in a number of ways, including summarizing important ecosystem components and processes as well as facilitating communication, discussion and debate about the nature of the system and important management issues. This process can lead to hypotheses regarding future changes, likely results of alternative management actions, identification of monitoring indicators, and ultimately, interpretation of monitoring results. As a first step towards developing a monitoring program, the 16 refuges in Alaska each created a conceptual model of their refuge and the landscape context. Models include prominent ecosystem components, drivers, and processes by which components are linked or altered. The Alaska refuge system also recognizes that designing and implementing monitoring at regional and ecoregional extents has numerous scientific, fiscal, logistical, and political advantages over monitoring conducted exclusively at refuge-specific scales. Broad-scale monitoring is particularly advantageous for examining phenomena such as climate change because effects are best interpreted at broader spatial extents. To enable an ecoregional perspective, a rationale was developed for deriving ecoregional boundaries for four ecoregions (Polar, Interior Alaska, Bering Coast, and North Pacific Coast) from the Unified Ecoregions of Alaska. Ecoregional models were then developed to illustrate resources and processes that operate at spatial scales larger than individual refuges within each ecoregion. Conceptual models also were developed for adjacent marine areas, designated as the North Pacific, Bering Sea, and Beaufort-Chukchi Sea Marine Ecoregions. Although many more conceptual models will be required to support development of a regional monitoring program, these definitions of ecoregions and associated conceptual models are an important foundation.
To solve the problem of ignoring the calculation of environment pollution in traditional ecological footprint model accounts, this paper put forward an optimized ecological footprint (EF) model, taking the pollution footprint into account. In the meantime, the environmental capacity's calculation was also added into the system of ecological capacity, and further used to do ecological assessment of Pearl River Delta urban agglomeration in 2005. The results showed a perfect inosculation between the ecological footprint and the development characteristics and spatial pattern, and illustrated that the optimized EF model could make a better orientation for the environmental pollution in the system, and also, could roundly explain the environmental effects of human activity. The optimization of ecological footprint model had better integrality and objectivity than traditional models. PMID:18975759
Most simulationmodels evolve over time through a number of different metamorphic states. These states are typical to most simulation efforts within a specific simulation category (i.e. health care, military, material handling etc.). Using a cursory SWOT (strengths, weaknesses, opportunities, threats) analysis approach, this paper seeks to define the states as they occur in a typical automated material handling simulation
The capability of ecologicalmodels to make precise predictions was questioned with the discovery of chaos. Here it is shown that an alternative form of unpredictability is associated with some nonlinear models. The notion of a Wada basin, in which three or more basins share complexly interdigitated boundaries, represents this new form of unpredictability. It signifies that a single point
Summary Several models have been proposed to explain the variation that exists in female social relationships among diurnal primate species. While there are similarities among them, notably in the ecological cause of agonistic relationships among females within groups, their differences are most useful in testing which of the models most accurately reè ects the real world. These include the question
This paper examines the use of a behavioral-ecologicalmodel to diagnose and prescribe interventions for a community problem. The paper is presented as a case study of a community-based organization that used the model in the treatment and prevention of Chicano gang delinquency. Other purposes of this work included a replication and extension of similar work performed in a different
A number of models are available for exposure assessment; however, few are used as tools for both human and ecosystem risks. This discussion will consider two modeling frameworks that have recently been used to support human and ecological decision making. The study will compare ...
In order to study complex environmental and ecological problems of Poyang Lake it is necessary to integrate or modify various existing models including hydrological, biological, social economic and other models with GIS techniques. This paper firstly discuses the construction of digital watershed platform for Poyang Lake, which is an integrated GIS environment for spatial data pre-processing and post-processing as well
Geying Lai; Jie Chen; Yinwen Liu; Yu Fang; Meijuan Luo
|Presents family systems model for understanding adaptation and coping in childhood chronic illness. Provides overview of systems and social-ecological theories relevant to this population. Reviews literature on stress and coping in these families. Examines unique issues and discusses importance of these models for responding to families with…
Discussed is a comprehensive, ecologically based paradigm applicable across cultures and created to assess the effects of abusive traumatic experiences, the Trauma Outcome Process Assessment (TOPA) model (Rasmussen, 1999, 2004, 2007; Rasmussen, Burton, & Christopherson, 1992). The TOPA model comprehensively assesses the risk and protective factors and trauma outcomes that contribute to self-destructive and\\/or abusive behavior in youth. TOPA interventions
Consistent evidence demonstrates that many women who encounter the trauma of rape experience a range of both acute reactions and chronic psychological sequelae. This article reviews both the short- and long-term psychological adjustment issues associated with rape. In addition, we propose a culturally inclusive ecologicalmodel of sexual assault recovery (CIEMSAR), which integrates and extends existing models to better examine
We study a version of the Tangled Nature model of evolutionary ecology redefined in a phenotype space where mutants have properties correlated to their parents. The model has individual-based dynamics whilst incorporating species scale competitive constraints and a system scale resource constraint. Multiple species arise that coexist in a species interaction network with evolving global properties. Both the mean interaction
Abstract KRIPLANI NIKHIL, M. Transistor Modeling using advanced circuit simulator technology. (Under the direction of Michael B. Steer) The advanced MOSFET model based on the Berkeley Short Channel IGFET
This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...
In this paper we discuss verification and validation of simulationmodels. Four different approaches to deciding model validity are described; two different paradigms that relate verification and validation to the model development process are presented; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are discussed; a way to document results is given; a
Based on system analysis principles, by reviewing relevant theory and literature, got the lottery sales impact factor system. Draw out the lottery sales system causal feedback map by using system dynamics, and on this basis, established the lottery sales system flow diagram simulationmodel. This model can be used to simulate and analyze the various factors of the lottery sales;
The Oil Market Simulation (OMS) model is a LOTUS 1-2-3 spreadsheet that simulates the world oil market. OMS is an annual model that projects the world oil market through the year 2010 from a data base that begins in 1979. The geographic coverage includes ...
The purpose of this document is to lay out a plan for research on Crowd Control Modeling and Simulation. Models and simulations that predict or describe crowd behavior do not exist at the present time in a form that could be used to describe the dynamics ...
D. Scholl P. Mason L. Sayegh R. Constable A. Tijerina
Advances in technology allow Computer SimulationModels (CSM) to be used as a powerful tool to aid military decision makers. This thesis explores the usefulness of one of these models, the Joint Tactical Simulation (JTS). First, this thesis outlines the i...
Drylands comprise one-third of the Earth’s land area. They pose research, management, and policy challenges impacting the livelihoods of 2.5 billion people. Desertification is said to affect some 10-20% of the drylands and is assumed to expand with climate change and population growth. Recent paradigms stress the importance of understanding linkages between human-ecological (H-E) systems in order to achieve sustainable management policies. Understanding coupled H-E systems is difficult at local levels. It represents an even greater challenge at regional scales to guide priorities and policy decisions at national and international levels. System dynamic modelling may help facilitating the probblem. Desertification and land degradation are often modelled and mathematically defined in terms of soil erosion. The soil erosion process is usually described as a function of vegetation ground cover, rainfall characteristics, topography, soil characteristics and land management. On-going research based on system dynamic modelling, focussing on elucidating the inherent complexity of H-E systems across multiple scales, enables an assessment of the relative roles that climate, policy, management, land condition, vulnerability and human adaptation may play in desertification and dryland development. An early approach (1995) to study desertification through an H-E coupled model considered desertification to be stress beyond resilience, i.e. irreversible, using a predator-prey system approach. As most predator-prey models, it was based on two linked differential equations describing the evolution of both a human population (predator) and natural resources (prey) in terms of gains, losses and interaction. A recent effort used a model approach to assess desertification risk through system stability condition analysis. It is based on the assumption that soil erosion and the soil sub-system play an overriding final role in the desertification processes. It is stressing the role and importance of economic units, production costs, investments and profitability in natural resources exploitation. This paper presents a recently developed coupled H-E system dynamic model to simulate and analyse desertification syndromes. The model integrates socio-economic drivers with bio-physical drivers of biomass production and land degradation. It is based on the UN and GEF definitions of desertification. It analyses and simulates dryland dynamics and desertification through differential equations and numeric simulation. The model relates population pressure and dynamics over time to the growth and availability of biomass resources. The human population stock is described as a function of growth rate, death rate and resources dependent migration of people. The relative growth rate of the stock of resources is modelled as a function of climate and human exploitation pressure affecting the removal of resources, soil erosion and water availability over time. The model is applied, demonstrated and discussed for combinations of time series of simulated and observed data referring to “desertification” cases in the Sahel, the Mediterranean and Inner Mongolia, China. The results are compared to existing land and population related statistics and remotely sensed observations opening for land system “carrying capacity” analysis and discussions.
Taking the spatiotemporal heterogeneity of water-heat condition into consideration, the traditional ecological footprint (EF) model was modified with net primary productivity (NPP). In the meanwhile, water resource EF was calculated to complement the deficiency of water EF account which only included water's fishing function. The EF dynamics of Dongying City from 1996 to 2003 was analyzed by using the modified model. Based on traditional model, the EF of Dongying City in 1996-2003 increased from 1.766 hm2 to 2.644 hm2, and the ecological capacity (EC) decreased from 0.889 hm2 to 0.813 hm2; while based on the modified model, the EF increased from 2.819 hm2 to 3.776 hm2, and the EC decreased from 1.935 hm2 to 1.865 hm2. Comparing with that from traditional model, the ecological pressure calculated by the modified model was lesser, which suggested that to increase the utilization of water resource would alleviate the ecological pressure on the region. The modified EF model was more precise to reflect the natural resource utilization of Dongying City. PMID:19899481
This book is a synthesis of what has been learned about ecological succession from the process of developing the models for the various systems which typically consisted of starting with the FORET model (an Appalachian deciduous forest). Modifying, testing, and applying such a model is the core of this work. Contents, abridged: Forest succession. Computer models of forest succession. Patch dynamics in forested mosaics. Categories of dynamic landscapes. A theory of forest dynamics. Index.
Guyton's original integrative physiology model was a milestone in integrative physiology, combining significant physiological knowledge with an engineering perspective to develop a computational diagrammatic model. It is still used in research and teaching, with a small number of variants on the model also in circulation. However, though new research has added significantly to the knowledge represented by Guyton's model, and significant advances have been made in computing and simulation software, an accepted common platform to integrate this new knowledge has not emerged. This paper discusses the issues in the selection of a suitable platform, together with a number of current possibilities, and suggests a graphical computing environment for modelling and simulation. By way of example, a validated version of Guyton's 1992 model, implemented in the ubiquitous Simulink environment, is presented which provides a hierarchical representation amenable to extension and suitable for teaching and research uses. It is designed to appeal to the biomedical engineer and physiologist alike. PMID:20576310
Mangourova, Violeta; Ringwood, John; Van Vliet, Bruce
This paper employs ecological footprint analysis as a potential non-monetary metric of human consumption and ecological productivity in a simulation-modeling framework, applied to North America. The ecological footprint provides an indirect basis for considering the long-term ecological risk and sustainability of human settlements, regions or, in this case, a continent. We examine several scenarios for human consumption, ecological productivity and
Two new models for 'slip-stick' friction are presented. One, called the 'bristle model,' is an approximation designed to capture the physical phenomenon of sticking. This model is relatively inefficient numerically. The other model, called the 'reset integrator model,' does not capture the details for the sticking phenomenon, but is numerically efficient and exhibits behavior similar to the model proposed by
High performance computing is leading to unprecedented volumes of data. Relational databases offer a robust and scalable model for storing and analyzing scientific data. However, these features do not come without a cost—significant design effort is required to build a functional and efficient repository. Modeling protein simulation data in a relational database presents several challenges: the data captured from individual simulations are large, multi-dimensional, and must integrate with both simulation software and external data sites. Here we present the dimensional design and relational implementation of a comprehensive data warehouse for storing and analyzing molecular dynamics simulations using SQL Server.
This report provides documentation of the Oil Market Simulation (OMS) Model, the principal model used by the Energy Information Administration (EIA) to project future world oil prices. The OMS model is continually being updated and improved. The methodolo...
'Back-to-the-Future’ (BTF) attempts to solve the ‘fisheries crisis’ by using past ecosystems as policy goals for the future.\\u000a BTF provides an integrative approach to the strategic management of marine ecosystems with policies based on restoration ecology,\\u000a and an understanding of marine ecosystem processes in the light of findings from terrestrial ecology. BTF employs recent developments\\u000a in whole ecosystem simulationmodelling
Tony J. Pitcher; Cameron H. Ainsworth; Eny A. Buchary; Wai lung Cheung; Robyn Forrest; Nigel Haggan; Hector Lozano; Telmo Morato; Lyne Morissette
This paper reports results of research that developed a computerized simulationmodel for the aircraft line maintenance department in Continental Airlines. The original AUTOMOD model that was created duplicated the maintenance operations at Continental's major maintenance station at Newark. Modeling the day-to-day maintenance activities lead to the development of enhanced staffing models and a better understanding of resource requirements on
I propose a methodology of sensitivity analysis applicable to complex process-based models. In application and discussion of this methodology, a model is conceived as a mechanism that is composed by multiple interacting processes. In this approach, model structure is explicitly investigated by analyzing the relationship that exists between process interactions and the emergent properties of the model. The methodology focuses
We have developed 007, an intelligent modeling assistant that assists a human modeler in three main revision tasks: (i) representation of the physical models, (ii) clarification of goals and formulation of explicit requirements, and (iii) modification of the physical model. 007 helps users to formulate explicit, testable requirements and to assess the current model. It then executes generic repair plans
Water resources ecological footprint can directly reflect the pressure of human social and economic activities to water resources, and provide important reference for the rational utilization of water resources. Based on the existing ecological footprint models and giving full consideration of the water resources need of urban ecological system, this paper established a new calculation model of urban water resources ecological footprint, including domestic water account, process water account, public service water account, and ecological water requirement account. According to the actual situation of Shenyang City, the key parameters of the model were determined, and the water resources ecological footprint and ecological carrying capacity of the City were calculated and analyzed. From 2000 to 2009, the water resources ecological footprint per capita of the City presented an overall decreasing trend, but still had an annual ecological deficit. As compared to that in 2000, the water resources ecological footprint per capita was decreased to 0.31 hm2 in 2005, increased slightly in 2006 and 2007, and remained stable in 2008 and 2009, which suggested that the sustainable utilization of water resources in Shenyang City had definite improvement, but was still in an unsustainable development situation. PMID:23189707
This article describes and assesses the development of a major evaluation and policy research tool-microdata simulationmodeling-over the past two decades. The method of microdata simulationmodeling is described and its reliance on the development of large, nationally weighted household surveys is noted. After a brief tracing of the history of this evaluation method from the first-generation static models to
An individual-based simulation system is presented for modelingmultiple species at multiple trophic levels, on a spatially explicit, continuoustwo-dimensional landscape. Biologically motivated rules arespecified at an individual level, and resulting behaviors are observedat an ecosystem level. Individuals are represented by circles with freerange on a resource-producing plane. These circles grow allometricallywith biomass of fixed resources. Resource acquisition behaviorsinclude...
This paper outlines a seven-step planning process being implemented on two large river basin studies currently underway in North America. One study involves the management of lake levels and flows in Lake Ontario and the St. Lawrence River on the border between Canada and the US. The International Joint Commission that oversees all water management issues between these two countries supports this study. The other involves the Greater Everglades region in south Florida in the US. In both studies multiple agencies and multiple stakeholders are involved in an attempt to find better ways of meeting multiple economic, environmental and ecological objectives. Both studies were motivated by the desire to find ways of improving the habitat of ecosystems within their basins and at the same time providing no less, or if possible greater, economic and social benefits that are derived from reliable water supplies, flows, levels, and flood protection. The seven-step planning process attempts to provide a very transparent and fully participatory approach toward reaching a common vision among all agencies and stakeholders as to how their hydrological system can be adaptively managed to better meet current and future objectives. This paper presents the seven steps and focuses on how all the values of various objectives are being defined and considered, together, in an attempt to define what water management policy works best and to an agreement on just what is ‘best’.
Background Predicting the ecological niche and potential habitat distribution of a given organism is one of the central domains of ecological and biogeographical research. A wide variety of modeling techniques have been developed for this purpose. In order to implement these models, the users must prepare a specific runtime environment for each model, learn how to use multiple model platforms, and prepare data in a different format each time. Additionally, often model results are difficult to interpret, and a standardized method for comparing model results across platforms does not exist. We developed a free and open source online platform, the multi-models web-based (mMWeb) platform, to address each of these problems, providing a novel environment in which the user can implement and compare multiple ecological niche model (ENM) algorithms. Methodology mMWeb combines 18 existing ENMs and their corresponding algorithms and provides a uniform procedure for modeling the potential habitat niche of a species via a common web browser. mMWeb uses Java Native Interface (JNI), Java R Interface to combine the different ENMs and executes multiple tasks in parallel on a super computer. The cross-platform, user-friendly interface of mMWeb simplifies the process of building ENMs, providing an accessible and efficient environment from which to explore and compare different model algorithms.
Qiao, Huijie; Lin, Congtian; Ji, Liqiang; Jiang, Zhigang
|Proposes a teaching strategy to teach ecological concepts and terminology through the use of games and simulations. Includes examples from physiological ecology, population ecology, and ecosystem ecology. (Author/SOE)|
Ecologists have used agent-based models for a long time, but refer to them as “individual-based models” (IBMs). Common characteristics\\u000a of IBMs are discrete representation of unique individuals; local interactions; use of adaptive, fitness-seeking behaviour;\\u000a explicit representation of how individuals and their environment affect each other; and representation of full life cycles.\\u000a \\u000a Ecology has contributed to agent-based modelling in general by
This article discusses the application of the ecologicalmodel to formative research in a practical setting of a training program developed for the Child Growth Monitoring Project of the New York State WIC program. The ecologicalmodel was selected to guide the formative research because it offered a concrete framework to account for the reciprocal inter- action of behavior and
G. Newes-Adeyi; D. L. Helitzer; L. E. Caulfield; Y. Bronner
In the enhanced biological phosphorus removal (EBPR) process, the competition between polyphosphate accumulating organisms (PAO) and glycogen accumulating organisms (GAO) has been studied intensively in recent years by both microbiologists and engineers, due to its important effects on phosphorus removal performance and efficiency. This study addresses the impact of microbial ecology on assessing the PAO–GAO competition through metabolic modelling, focussing
A. Oehmen; G. Carvalho; C. M. Lopez-Vazquez; M. C. M. van Loosdrecht; M. A. M. Reis
Painted turtles (Chrysemys picta) are representatives of a vertebrate clade whose biology and phylogenetic position hold a key to our understanding of fundamental aspects of vertebrate evolution. These features make them an ideal emerging model system. Extensive ecological and physiological research provide the context in which to place new research advances in evolutionary genetics, genomics, evolutionary developmental biology, and ecological developmental biology which are enabled by current resources, such as a bacterial artificial chromosome (BAC) library of C. picta, and the imminent development of additional ones such as genome sequences and cDNA and expressed sequence tag (EST) libraries. This integrative approach will allow the research community to continue making advances to provide functional and evolutionary explanations for the lability of biological traits found not only among reptiles but vertebrates in general. Moreover, because humans and reptiles share a common ancestor, and given the ease of using nonplacental vertebrates in experimental biology compared with mammalian embryos, painted turtles are also an emerging model system for biomedical research. For example, painted turtles have been studied to understand many biological responses to overwintering and anoxia, as potential sentinels for environmental xenobiotics, and as a model to decipher the ecology and evolution of sexual development and reproduction. Thus, painted turtles are an excellent reptilian model system for studies with human health, environmental, ecological, and evolutionary significance. PMID:20147199
|This study examined how campus peer culture influences the ways in which multiracial students make meaning of their racial identity, and applies Urie Bronfenbrenner's ecologicalmodel of cognitive development to analyze elements in the college environment that stimulate or inhibit identity development. Discussion of the situation of multiracial…
Among rising rates of overweight and obesity, schools have become essential settings to promote health behaviors, such as physical activity (PA). As schools exist within a broader environment, the social ecologicalmodel (SEM) provided a framework to consider how different levels interact and influence PA. The purpose of this study was to provide insight on school-based PA promotion by investigating
Coccidioidomycosis is an endemic infectious disease in western North American deserts caused by the dimorphic ascomycete Coccidioides spp. Even though there has been an increase in the number of reported cases in the last years, few positive isolations have been obtained from soil samples in endemic areas for the disease. This low correlation between epidemiological and environmental data prompted us to better characterize the fundamental ecological niche of this important fungal pathogen. By using a combination of environmental variables and geospatially referenced points, where positive isolations had been obtained in southern California and Arizona (USA) and Sonora (Mexico), we have applied Genetic Algorithm for Rule Set Production (GARP) and Geographical Information Systems (GIS) to characterize the most likely ecological conditions favorable for the presence of the fungus. This model, based on environmental variables, allowed us to identify hotspots for the presence of the fungus in areas of southern California, Arizona, Texas, Baja California, and northern Mexico, whereas an alternative model based on bioclimatic variables gave us much broader probable distribution areas. We have overlapped the hotspots obtained with the environmental model with the available epidemiological information and have found a high match. Our model suggests that the most probable fundamental ecological niche for Coccidioides spp. is found in the arid lands of the North American deserts and provides the methodological basis to further characterize the realized ecological niche of Coccidioides spp., which would ultimately contribute to design smart field-sampling strategies. PMID:17395734
|Among rising rates of overweight and obesity, schools have become essential settings to promote health behaviors, such as physical activity (PA). As schools exist within a broader environment, the social ecologicalmodel (SEM) provided a framework to consider how different levels interact and influence PA. The purpose of this study was to provide…
The present paper contends that children with learning disabilities are better served when assessment and intervention are conceptualized within an ecological neuropsychology perspective than within the traditional deficit model perspective, which is the predominant approach to intervention in medical and educational settings. The deficit method conceptualizes problems as within the child, and the major consequence of this approach is that
Rik Carl D'Amato; Franci Crepeau-Hobson; Leesa V. Huang; Molly Geil
As most biologists are probably aware, technological advances in molecular biology during the last few years have opened up possibilities to rapidly generate large-scale sequencing data from non-model organisms at a reasonable cost. In an era when virtually any study organism can ‘go genomic’, it is worthwhile to review how this may impact molecular ecology. The first studies to put
A mathematical model for trophic and detrital dynamics of an Italian coastal lagoon is described, dominant importance is given to the ecological structure of the system. Three biotic components (phytoplankton producers, zooplankton consumers and bacterial pool decomposers) and three abiotic (nutrients, oxygen and organic matter) are considered. Temperature, solar radiation and wind are the environmental forcing functions acting on a
Vincent Hull; Chiara Mocenni; Margherita Falcucci; Nadia Marchettini
In this study, the authors tested a social ecologicalmodel of illness management in high-risk, urban adolescents with Type 1 diabetes. It was hypothesized that management behaviors would be associated with individual adolescent characteristics as well as family, peer, and provider relationships. Questionnaires were collected from 96 adolescents…
Bayesian statistical modeling has several benefits within an ecological context. In particular, when observed data are limited in sample size or representativeness, then the Bayesian framework provides a mechanism to combine observed data with other ''prior'' information. Prior information may be obtained from earlier studies, or in their absence, from expert knowledge. This use of the Bayesian framework reflects the
|Childhood anxiety is impairing and associated with later emotional disorders. Studying risk factors for child anxiety may allow earlier identification of at-risk children for prevention efforts. This study applied an ecological risk model to address how early childhood anxiety symptoms, child temperament, maternal anxiety and depression symptoms,…
Mian, Nicholas D.; Wainwright, Laurel; Briggs-Gowan, Margaret J.; Carter, Alice S.
The comprehensive aquatic systems model (CASM) was adapted for estimating ecological risks posed by toxic chemicals in rivers, lakes, and reservoirs in Québec, Canada. Populations of aquatic plants, invertebrates, and fish characteristic of these aquatic ecosystems were identified and generic food webs were constructed. Bioenergetics parameters that determine the growth dynamics of these populations were derived from published values for
Steven M. Bartell; Guy Lefebvre; Grégoire Kaminski; Michel Carreau; Kym Rouse Campbell
In combination with gender and culture, the authors argue that the migratory experience must be considered as a determinant of the health of immigrant women in its own right. Gender and other symbolic institutions are seen as intertwined in an ecologicalmodel of health. Bronfenbrenner's (1986) systems theory and a combination of theories of social cognition, social exchange and symbolic
Sediment is one of the primary stressors of concern for Total Maximum Daily Loads (TMDLs) for streams, and often it is a concern because of its impact on ecological endpoints. A modeling approach relating sediment to stream fish population dynamics is presented. Equations are d...
Marine protected area (MPA) networks have been proposed as a principal method for conserving biological diversity, yet patterns of diversity may ultimately complicate or compromise the development of such networks. We show how a series of ecological null models can be applied to assemblage data across sites in order to identify non-random biological patterns likely to influence the effectiveness of
Brice X. Semmens; Peter J. Auster; Michelle J. Paddack; Stuart A. Sandin
Wildlife tourism attractions are characterized as having intricately coupled human–wildlife interactions. Accordingly, the ability to mitigate negative impacts of tourism on wildlife necessitates research into the ecology of the system and of the human dimensions, since plans aimed at optimizing wildlife fitness must also be acceptable to tourists. We developed an integrated systems dynamics model for the management of tourist–stingray
Christina A. D. Semeniuk; Wolfgang Haider; Andrew Cooper; Kristina D. Rothley
Ecosystem health is a newly proposed concept that sets new goals for environmental management. Its definition, indexing and assessment methods are still being perfected. An EcologicalModeling Method (EMM) for lake ecosystem health assessment is proposed in this paper. The EMM's procedures are: (1) to analyze the ecosystem structure of a lake in order to determine the structure and complexity
Fu-Liu Xu; Richard W. Dawson; Shu Tao; Jun Cao; Ben-Gang Li
The article presents one systematic approach to the integration and explication of the ecologicalmodel of emotional disturbance in children (the development of disturbing interactions between children and their environments), which does not yet offer a coherent framework. (Author/DLS)
The evolutionary-ecologicalmodel presented here introduces a new concept, 'fission', in order to highlight the possibility of economically rational outcomes manifesting inert demand for human capital. The apparent paradox between the availability of skilled labour and an unresponsiveness of employers to its availability is shown to be the consequence of employer risk avoidance in the presence of 'fission', the dis-mantling
In this study, the authors tested a social ecologicalmodel of illness management in high-risk, urban adolescents with Type 1 diabetes. It was hypothesized that management behaviors would be associated with individual adolescent characteristics as well as family, peer, and provider relationships. Questionnaires were collected from 96 adolescents in poor metabolic control and their primary caregivers. Variables in each system
Sylvie Naar-King; Cheryl-Lynn Podolski; Deborah A. Ellis; Maureen A. Frey; Thomas Templin
The development of large-scale ecologicalmodels depends implicitly on a concept known as hierarchy theory which views biological systems in a series of hierarchical levels (i.e., organism, population, trophic level, ecosystem). The theory states that an explanation of a biological phenomenon is provided when it is shown to be the consequence of the activities of the system's components, which are
Understanding the complexity and ecological organization of protected area ecosystems, and their bioregional surroundings, is fundamental to maintaining their integrity. This research set out to integrate the bodies of systems and hierarchy theory to establish a framework for developing a conceptual model that would synthesize knowledge from diverse fields and identify key system processes, thereby providing new insight into ecosystem
As part of a broader exploratory effort to develop ecological risk assessment approaches to estimate potential chemical effects on non-target populations, we describe an approach for developing simple population models to estimate the extent to which acute effects on individual...
Ecological processes and hydrological processes are very tightly connected with each other. Especially, to estimate the amount of water outflow and water retention in forest, it is needed to quantify the role of vegetation in the forest. For this reason, Eco-hydrological modeling provides an useful tool to understand the forest ecosystem processes and services. But because the numerous processes is
E. Kim; S. Kang; A. Lee; S. Kim; K. Kim; J. Kim; D. Lee
The ultimate objective of this work is to provide a spatially distributed database of soil properties to serve as inputs to modelecological processes in western forests at the landscape scale. The Central Western Oregon Cascades are rich in biodiversity and they are a fascinati...
The complex network of the marine food chain with all the details of the behavior of individuals and the interactions with physical processes cannot be included into one generic model. Modelling requires simplification and idealization. The reduction of complex problems to simpler, but tractable problems are guided by the questions being addressed. Consequently, a variety of different models have been
Bioturbation is one of the most widespread forms of ecological engineering and has significant implications for the structure and functioning of ecosystems, yet our understanding of the processes involved in biotic mixing remains incomplete. One reason is that, despite their value and utility, most mathematical models currently applied to bioturbation data tend to neglect aspects of the natural complexity of bioturbation in favour of mathematical simplicity. At the same time, the abstract nature of these approaches limits the application of such models to a limited range of users. Here, we contend that a movement towards process-based modelling can improve both the representation of the mechanistic basis of bioturbation and the intuitiveness of modelling approaches. In support of this initiative, we present an open source modelling framework that explicitly simulates particle displacement and a worked example to facilitate application and further development. The framework combines the advantages of rule-based lattice models with the application of parameterisable probability density functions to generate mixing on the lattice. Model parameters can be fitted by experimental data and describe particle displacement at the spatial and temporal scales at which bioturbation data is routinely collected. By using the same model structure across species, but generating species-specific parameters, a generic understanding of species-specific bioturbation behaviour can be achieved. An application to a case study and comparison with a commonly used model attest the predictive power of the approach.
Schiffers, Katja; Teal, Lorna Rachel; Travis, Justin Mark John; Solan, Martin
Several mercury cycling models, including general mass balance approaches, mixed-batch reactors in streams or lakes, or regional process-based models, exist to assess the ecological exposure risks associated with anthropogenically increased atmospheric mercury (Hg) deposition, so...
Crop simulationmodels (CSM) were built to simulate the crop response to environment and soil on plot levels and were gradually applied for simulating regional behaviours of crop. Most of the models applied for simulating regional behaviour are general crop sim- ulation models or crop-specific simulationmodels. The models, which use cultivar specific information, are difficult to apply on regional
Groundwater solute transport models are now capable of simulating the migration of contaminants in complex real-world systems when sufficient data are available. A variety of numerical methods have been applied successfully to solving the transport equation, and no single method is best for all problems. Over the past 10 to 15 years techniques have been developed to simulate chemical reactions
This paper describes our design of a simulation environment for electronic textiles (e-textiles) and our experiences with that environment. This simulation environment, based upon Ptolemy II, enables us to model a diverse range of areas related to the design of electronic textiles, including the physical environment they will be used in, the behavior of the sensors incorporated into the fabric,
Thomas Martin; Mark Jones; Joshua Edmison; Tanwir Sheikh; Zahi Nakad
The use of Computational Fluid Dynamics (CFD) and in particular Large Eddy Simulation (LES) codes to model fires provides an efficient tool for the prediction of large-scale effects that include plume characteristics, combustion product dispersion, and heat effects to adjacent objects. This paper illustrates the strengths of the Fire Dynamics Simulator (FDS), an LES code developed by the National Institute
Noah L. Ryder; Jason A. Sutula; Christopher F. Schemel; Andrew J. Hamer; Vincent Van Brunt
Hydrologic processes are sensitive to the spatial distribution of hydrologic parameters in watersheds. A distributed hydrologic model which can simulate various components of a watershed hydrologic cycle such as surface water, channel water, soil water and groundwater as well their interactions is used to simulate various hydrologic processes in the Meilin watershed in this paper. The parameters with physical meanings
Our goal is to simulate the full hair geometry, consisting of approximately one hundred thousand hairs on a typical human head. This will require scalable methods that can simulate every hair as opposed to only a few guide hairs. Novel to this approach is that the individual hair\\/hair interactions can be modeled with physical parameters (friction, static attraction, etc.) at
Our goal is to simulate the full hair geometry, consisting of ap- proximately one hundred thousand hairs on a typical human head. This will require scalable methods that can simulate every hair as opposed to only a few guide hairs. Novel to this approach is that the individual hair\\/hair interactions can be modeled with physical parameters (friction, static attraction, etc.)
The paper Modeling Physics with Easy Java Simulations describes the use of the Easy Java Simulations (Ejs) modeling and authoring tool and shows how this tool can be used to teach mechanics concepts using computer modeling. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their results, and to communicate their results with others. The combination of computer modeling with theory and experiment can achieve insight and understanding that cannot be achieved with only one approach. Journal article available from http://scitation.aip.org/tpt/
Riverine backwater wetlands within river floodplains provide valuable ecological functions such as acting as filters for suspended sediment, nutrients and pesticides entering from adjacent agricultural fields, as well as habitat and refugia for aquatic biota. A 500 m long, 20 m wide riverine backwa...
Mathematical dosimetry models incorporate mechanistic determinants of chemical disposition in a living organism to describe relationships between exposure concentration and the internal dose needed for PBPK models and human health risk assessment. Because they rely on determini...
Abstract Many students are familiar with the idea of modeling chemical reactions in terms of ordinary dieren tial equations. However, these deterministic reaction rate equations are really a certain large-scale limit of a sequence of ner-scale probabilistic models. In studying this hierarchy of models, students can be exposed to a range of modern ideas in applied and compu- tational mathematics.
Water quality modelling has been employed as an effective tool to investigate the ecological situation of surface water sources. Within a researching collaboration of Vietnamese and French scientists, one portion, 40 km, of the Nhue river, outskirts of Hanoi city, northern Vietnam, has been investigated since the river has been highly impacted from anthropogenic activities and one 1-D ecological river model was formed based on the investigation. In this paper, biochemical process equations integrated with hydraulic conditions and human alterations are presented as the basis for ecological variation of this river system. Investigation showed that at the origin the river water remains untouched (nutrients are low in natural tropical water) while downstream the river is full of domestic pollutants (organic materials and nutrients). From the hydraulic, biological, chemical data and fieldwork experiments, the sensitivity analysis and parameter estimation have been carried out to verify the biochemical processes and optimise this model. Most calculations (simulation, sensitivity functions and parameter estimation) were performed with AQUASIM, a computer program designed for simulation and data analysis of 1-D river and other aquatic systems. The other supporting calculations for system analysis were implemented with IDENT based on output of a sensitivity analysis carried out with AQUASIM. The simulation results accomplished with available data indicate that the sediment exchanges and biodegradation processes emerge as the most important features that influence the water quality of the river where water is usually overloaded by domestic wastewater and where hydraulic characters are less pronounced. The model construction and simulation results have also pointed out that the river water quality has been spoiled dramatically after the main open-air sewer of the Hanoi city, the To Lich river, excesses to the Nhue. Beside, a metal speciation module was proposed to integrate with existing biochemical model in order to simulate the metal fractions in water column and metal exchange between river water and sediment.
A stochastic computer model for simulating the actions and behavior of nuclear power plant maintenance personnel is described. The model considers personnel, environmental, and motivational variables to yield predictions of maintenance performance quality and time to perform. The mode has been fully developed and sensitivity tested. Additional evaluation of the model is now taking place.
We present a brief overview of past and future applications of high performance computing in biofilm modeling. In particular we show that even relative simple two-dimensional models lead to computing expensive simulation experiments, due to data uncertainties inherent in all biofilm models.
Hermann J. Eberl; Nasim Muhammad; Rangarajan Sudarsan
A mathematical model was developed for simulating a convective batch lumber drying process. The model incorporates mass and heat transfer relationships within the lumber stack, as well as thermodynamic properties of the wood and drying air. It takes into account the change of air properties along the stack and its effect on the mass and heat transfer parameters. The model
The paper discusses the development of the Advanced Utility SimulationModel (AUSM), developed for the National Acid Precipitation Assessment Program (NAPAP), to forecast air emissions of pollutants from electric utilities. USM integrates generating unit engineering detail with d...
Stakeholders often have competing interests when selecting or planning new power plants. The purpose of developing this preliminary Electricity Portfolio SimulationModel (EPSim) is to provide a first cut, dynamic methodology and approach to this problem,...
|Describes a simulation using dice-tossing students in a population cluster to model the growth of cancer cells. This growth is recorded in a scatterplot and compared to an exponential function graph. (KHR)|
This report deals with the continuing effort to develop a chemical kinetic mechanism to describe the formation of photochemical smog. Using the technique of computer modeling to simulate smog chamber data, several explicit kinetic mechanisms for specific ...
Dielectric elastomers are used as base material for so-called electroactive polymer (EAP) actuators. A procedure and a specific constitutive model (for the acrylic elastomer VHB 4910) are presented in this work for finite element modeling and simulation of dielectric elastomer actuators of general shape and set-up. The Yeoh strain energy potential and the Prony series are used for describing the large strain time-dependent mechanical response of the dielectric elastomer. Material parameters were determined from uniaxial experiments (relaxation tests and tensile tests). Thereby the inverse problem was solved using iterative finite element calculations. A pre-strained circular actuator was built and activated with a predefined voltage. A three-dimensional finite element model of the circular actuator was created and the electromechanical activation process simulated. Simulation and actual measurements agree to a great extent, thus leading to a validation of both the constitutive model and the actuator simulation procedure proposed in this work.
Mathematical modelling and simulation are important tools when dealing with engineering systems that today are becoming increasingly more complex. Integrated production and recycling of materials are trends that give rise to heterogenous systems, which ar...
Enhancement of simulation options for stormwater best management practices (BMPs) and hydrologic source control is discussed in the context of the EPA Storm Water Management Model (SWMM). Options for improvement of various BMP representations are presented, with emphasis on inco...
Prediction uncertainty in stochastic simulationmodels can be described by a hierarchy of components: stochastic variability at the lowest level, input and parameter uncertainty at a higher level, and structural model uncertainty at the top. It is argued that a usual paradigm for analysis of input uncertainty is not suitable for application to structural model uncertainty. An approach more likely to produce an acceptable methodology for analyzing structural model uncertainty is one that uses characteristics specific to the particular family of models.
McKay, M.D.; Morrison, J.D. [Los Alamos National Lab., NM (United States). Technology and Safety Assessment Div.
Abstract We present a framework for the simulation and formal analysis of workow,models. We discuss (i) how a workow,model, implemented in the BPEL language, can be transformed into a dataow,network model, (ii) how potentially incorrect execution paths can be incorporated, and (iii) how the properties of a workow can be formally veried,using the SPIN model checker. For the several model
Structural equation modeling is a multivariate statistical method that allows evaluation of a network of relationships between manifest and latent variables. In this statistical technique, preconceptualizations that reflect research questions or existing knowledge of system structure create the initial framework for model development, while both direct and indirect effects and measurement errors are considered. Given the interesting features of this
G. B. Arhonditsis; C. A. Stow; L. J. Steinberg; M. A. Kenney; R. C. Lathrop; S. J. McBride; K. H. Reckhow
|The authors introduce the concept of "ecosystems." An ecosystem is one in which there is a true transaction between mutually dependent partners, with the assumption on college campuses that either may change so that mutual benefit may result. A model for bringing about change is presented, and methodology for using the model is described.…
This paper presents guidelines for conducting verifica- tion, validation and accreditation (VV&A) of simulationmodels. Fifteen guiding principles are introduced to help the researchers, practitioners and managers better com- prehend what VV&A is all about. The VV&A activities are described in the modeling and simulation life cycle. A taxonomy of more than 77 V&V techniques is provided to assist simulationists
This paper compares the application of different versions of the simulated counterparts of the Wald test, the score test,\\u000a and the likelihood ratio test in one- and multiperiod multinomial probit models. Monte Carlo experiments show that the use\\u000a of the simple form of the simulated likelihood ratio test delivers relatively robust results regarding the testing of several\\u000a multinomial probit model
Good team members seem to have the ability to simulate what others on the team will do in different situations. Team researchers have long studied what makes an effective team. Their methodology has been to examine how high and low performing teams accomp...
Transformers of two different designs, an unencapsulated pot core and an encapsulated toroidal core, have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim's PSPICE and Anology's SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.
Transformers of two different designs; and unencapsulated pot core and an encapsulated toroidal core have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim`s PSPICE and Anology`s SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.
The fugacity-based food web model was developed to simulate the bioaccumulation of dichloro-diphenyl-trichloroethanes (DDTs) in the aquatic ecosystem in the Bohai Bay. The internal exposure levels (IELs) of DDTs in various organism categories were calculated. Monte Carlo-based uncertainty analysis was performed to get the of IEL distributions of DDTs in organisms. Probabilistic ecological risk assessment (ERA) was performed based on IEL distributions and internal species sensitivity distributions (SSDs). The results show that fugacities and bioaccumulation factors (BAFs) generally increased with increasing trophic level in the food web. Octanol-water partition coefficient (K(ow)), DDT levels in water and the lipid contents had the greatest influences on IELs in the organism bodies. The ecological risks of DDTs were relatively high. The risk order was p,p'-DDT>p,p'-DDE>p,p'-DDD. At an internal hazard quotient (HQ(int)) criterion of 1/5, the risk probabilities were 0.10 (0.055-0.17), 0.079 (0.045-0.13) and 0.053 (0.028-0.092) for p,p'-DDT, p,p'-DDE and p,p'-DDD, respectively. The results from ERA based on the internal exposure approximated those based on external exposure. The food web model is a feasible method to predict the extent of bioaccumulation and IELs of hydrophobic organic pollutants in organisms as a step to evaluate their risk posed on aquatic ecosystems. PMID:21075423
\\u000a Understanding species distributions in space and time is essential to ecology, evolution, and conservation biology. There\\u000a is a growing need for robust habitat models that can adequately predict species distributions across broad spatial scales\\u000a (Guisan and Thuiller 2005). An invaluable tool for conservation biologists (Norris 2004), species distribution models can\\u000a be used to evaluate potential management actions, interpret the potential
Robert J. Fletcher Jr; Jock S. Young; Richard L. Hutto; Anna Noson; Christopher T. Rota
Model averaging, specifically information theoretic approaches based on Akaike’s information criterion (IT-AIC approaches),\\u000a has had a major influence on statistical practices in the field of ecology and evolution. However, a neglected issue is that\\u000a in common with most other model fitting approaches, IT-AIC methods are sensitive to the presence of missing observations.\\u000a The commonest way of handling missing data is
Sexual satisfaction is an integral component of sexual health and well-being, yet we know little about which factors contribute\\u000a to it among lesbian\\/bisexual women. To examine a proposed ecologicalmodel of sexual satisfaction, we conducted an internet\\u000a survey of married heterosexual women and lesbian\\/bisexual women in committed same-sex relationships. Structural equation modeling\\u000a included five final latent variables for heterosexual women
Alison W. Henderson; Keren Lehavot; Jane M. Simoni
While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity modelsimulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched netw...
Quantitative Modeling has been the basis of most of the initial research in operations, labeled as Operational Research in Europe, and was the basis of initial management consulting and Operations Research in the USA. Initially, quantitative modeling in Operational Research was oriented very much towards solving real-life problems in operations management rather than towards developing scientific knowledge. Later however, especially
The relative risk model (RRM) was applied in regional ecological risk assessments successfully. In this study, the RRM was developed through increasing the data of risk source and introducing the source-stressor-habitat exposure filter (SSH), the endpoint-habitat exposure filter (EH) and the stressor-endpoint effect filter (SE) to reflect the meaning of exposure and effect more explicit. Water environment which include water quality, water quantity and aquatic ecosystems was selected as the ecological risk assessment endpoints. The Luanhe River Basin located in the North China was selected as model case. The results showed that there were three low risk regions, one medium risk region and two high risk regions in the Luanhe River Basin. The results also indicated habitat destruction was the largest stressor with the risk scores as high as 11.87 for the Luanhe water environment, the second was oxygen consuming organic pollutants (9.28) and the third was nutrients (7.78). So these three stressors were the main influencing factors of the ecological pressure in the study area. Furthermore, animal husbandry was the biggest source with the risk scores as high as 20.38, the second was domestic sewage (14.00), and the third was polluting industry (9.96). For habitats, waters and farmland were enduring the bigger pressure and should be taken considerable attention. Water deterioration and ecological service values damaged were facing the biggest risk pressure, and secondly was biodiversity decreased and landscape fragmentation. PMID:20683654
We developed an integrated hydroecological model to provide a comprehensive set of hydrologic variables representing five major components of the flow regime at 856 aquatic-invertebrate monitoring sites in New Jersey. The hydroecological modelsimulates streamflow by routing water that moves overland and through the subsurface from atmospheric delivery to the watershed outlet. Snow accumulation and melt, evapotranspiration, precipitation, withdrawals, discharges, pervious- and impervious-area runoff, and lake storage were accounted for in the water balance. We generated more than 78 flow variables, which describe the frequency, magnitude, duration, rate of change, and timing of flow events. Highly correlated variables were filtered by principal component analysis to obtain a non-redundant subset of variables that explain the majority of the variation in the complete set. This subset of variables was used to evaluate the effect of changes in the flow regime on aquatic-invertebrate assemblage structure at 856 biomonitoring sites. We used non-metric multidimensional scaling (NMS) to evaluate variation in aquatic-invertebrate assemblage structure across a disturbance gradient. We employed multiple linear regression (MLR) analysis to build a series of MLR models that identify the most important environmental and hydrologic variables driving the differences in the aquatic-invertebrate assemblages across the disturbance gradient. The first axis of NMS ordination was significantly related to many hydrologic, habitat, and land-use/land-cover variables, including the average number of annual storms producing runoff, ratio of 25-75% exceedance flow (flashiness), diversity of natural stream substrate, and the percentage of forested land near the stream channel (forest buffer). Modifications in the hydrologic regime as the result of changes in watershed land use appear to promote the retention of highly tolerant aquatic species; in contrast, species that are sensitive to hydrologic instability and other anthropogenic disturbance become much less prevalent. We also found strong relations between an index of invertebrate-assemblage impairment, its component metrics, and the primary disturbance gradient. The process-oriented watershed modeling approach used in this study provides a means to evaluate how natural landscape features interact with anthropogenic factors and assess their effects on flow characteristics and stream ecology. By combining watershed modeling and indirect ordination techniques, we were able to identify components of the hydrologic regime that have a considerable effect on aquatic-assemblage structure and help in developing short- and long-term management measures that mitigate the effects of anthropogenic disturbance in stream systems.
Kennen, J. G.; Kauffman, L. J.; Ayers, M. A.; Wolock, D. M.; Colarullo, S. J.
The DMSS software support effort enhanced the capabilities and value of DMSS by accomplishing the following four objectives: (1) Addition of VATS/Pave Tack and Maverick Missile models; (2) Enhancing the existing software; (3) Creating meaningful, up-to-date documentation; and (4) Providing comprehensive training. The new models were developed using top-down structuring techniques and were implemented in RATFOR (a structured FORTRAN preprocessor). The existing models were restructured using top-down structuring techniques, RATFOR, and meaningful comments. The documentation was updated to adhere to MIL-STD-483 and 490.
An eco-hydrodynamic model was used to estimate the carrying capacity of pollutant loads and response of water quality to environmental change in Yeoja Bay, Korea. An energy-system model also was used to simulate the fluctuation in nutrients and organic matter in the bordering wetland. Most water quality factors showed a pulsed pattern, and the concentrations of nutrients and organic matter of seawater increased when input loads of nutrients increased due to freshwater discharge. The well-developed tidal zones and wetlands in the northern area of the bay were highly sensitive to input loads. Residence times of water, chemical oxygen demand (COD), and dissolved inorganic nitrogen (DIN) within the bay were estimated to be about 16 days, 43.2 days, and 50.2 days, respectively. Water quality reacted more sensitively to the effects of nitrogen and phosphorus input than to COD. A plan to reduce the present levels of COD and dissolved inorganic phosphorus (DIP) by 20-30% and DIN by at least 50% in pollutant loads is needed for satisfying the target water quality criteria. The natural removal rate of nutrients in wetlands by reeds was assessed to be approximately 10%.
Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of autonomous, interacting agents. Computational advances have made possible a growing number of agent-based models across a variety of application domains. Applications range from modeling agent behavior in the stock market, supply chains, and consumer markets, to predicting the spread of epidemics, mitigating the threat of bio-warfare,
We aligned two fundamentally different models of disea se transmission after a bioterrorist attack: a multi-agent model (BioWar) and the conventio nal Susceptible-Infected-Recovered (SIR) model. The purpose of this alignment is part of a gre ater validation process for BioWar. We conducted two model alignment studies based on smallpox and anthrax attack simulations. From these two studies we were able
Li-Chiou Chen; Kathleen M. Carley; Boris Kaminsky; Tiffany Tummino; Elizabeth Casman; Douglas Fridsma; Alex Yahja
This online report, published in Conservation Ecology, describes the framework for web-based collaborative teaching, and provides the layout of an ecologicalmodeling course as an example of how this method of teaching can be implemented. The course content consists of reading materials that describe the theory of systems analysis and modeling, guidelines on how models can be built, and numerous examples and illustrations. The interactive portion includes exercises that can be discussed with and evaluated by the instructor, and provides a means to mimic class discussions. In addition to the course content, the report also offers a discussion of the availability and relevance of other web-based tools, including links to those discussed.
Circular economy (CE) focuses on resource-productivity and eco-efficiency improvement in a comprehensive way, especially on the industrial structure optimization of new technology development and application, equipment renewal and management renovation. The leather industry on the one side boosts the local economic development, on the other side however leads to the tremendous environment pollution and biological chains destruction. The CE model
Critical review of explanations for patterns of natural succession suggests a strong, common basis for theoretical understanding, but also suggests that several well known models are incomplete as explanations of succession. A universal, general cause for succession is unlikely, since numerous aspects of historical and environmental circumstances will impinge on the process in a unique manner. However, after disturbance, occupation
Sediment is one of the main stressors of concern for TMDLs (Total Maximum Daily Loads) for streams, and often it is a concern because of its impact on biological endpoints. The National Research Council (NRC) has recommended that the EPA promote the development of models that ca...
|The Developing Mindful Learners Model (DMLM), developed within the framework of Howard Gardner's multiple intelligences theory, connects three factors--content, framework, and world vision--for the purpose of helping underachieving students to become more "mindful": i.e., to become one who welcomes new ideas, considers more than one perspective,…
Stream hydrology strongly affects the structure of aquatic communities. Changes to air temperature and precipitation driven by increased greenhouse gas concentrations are shifting timing and volume of streamflows potentially affecting these communities. The variable infiltration capacity (VIC) macroscale hydrologic model has been employed at regional scales to describe and forecast hydrologic changes but has been calibrated and applied mainly to
Seth J. Wenger; Charles H. Luce; Alan F. Hamlet; Daniel J. Isaak; Helen M. Neville
We study a model for competing species that explicitly accounts for effects due to discreteness, stochasticity and spatial extension of populations. If a species does better locally than the other by an amount ?, the global outcome depends on the initial densities (uniformly distributed in space), ? and the size of the system. The transition point moves to lower values
|Despite a recent focus on engaging students in epistemic practices, there is relatively little research on how learning environments can support the simultaneous, coordinated development of both practice and the knowledge that emerges from and supports scientific activity. This study reports on the co-construction of modeling practice and…
The Developing Mindful Learners Model (DMLM), developed within the framework of Howard Gardner's multiple intelligences theory, connects three factors--content, framework, and world vision--for the purpose of helping underachieving students to become more "mindful": i.e., to become one who welcomes new ideas, considers more than one perspective,…
By adopting FVCOM-simulated 3-D physical field and based on the biological processes of chub mackerel (Scomber japonicas) in its early life history from the individual-based biological model, the individual-based ecologicalmodel for S. japonicas at its early growth stages in the East China Sea was constructed through coupling the physical field in March-July with the biological model by the method of Lagrange particle tracking. The model constructed could well simulate the transport process and abundance distribution of S. japonicas eggs and larvae. The Taiwan Warm Current, Kuroshio, and Tsushima Strait Warm Current directly affected the transport process and distribution of the eggs and larvae, and indirectly affected the growth and survive of the eggs and larvae through the transport to the nursery grounds with different water temperature and foods. The spawning grounds in southern East China Sea made more contributions to the recruitment to the fishing grounds in northeast East China Sea, but less to the Yangtze estuary and Zhoushan Island. The northwestern and southwestern parts of spawning grounds had strong connectivity with the nursery grounds of Cheju and Tsushima Straits, whereas the northeastern and southeastern parts of the spawning ground had strong connectivity with the nursery grounds of Kyushu and Pacific Ocean. PMID:22937663
An ecologicalmodel is derived from recent studies, based on 60 years of empirical observations and experimental data, that conceptualizes how Cootes Paradise Marsh was transformed from a lush emergent marsh with considerable ecological diversity in all trophic levels, to one that is currently turbid, devoid of vegetation, and dominated by a few exotic plant and fish species. This conceptual
Although the systematic utility of ecological niche modeling is generally well known (e.g., concerning the recog- nition and discovery of areas of endemism for biogeographic analyses), there has been little discussion of applications concerning species delimitation, and to date, no empirical evaluation has been conducted. However, ecological niche mod- eling can provide compelling evidence for allopatry between populations, and can
CHRISTOPHER J. RAXWORTHY; COLLEEN M. INGRAM; Nirhy Rabibisoa; RICHARD G. PEARSON
In this paper, on the basis of the theories and methods of ecology and ordinary differential equations, an ecologicalmodel with an impulsive control strategy and distributed time delay is established. By using impulsive equation theories, small amplitude perturbation skills and the comparison technique, we get the condition which guarantees the global asymptotical stability of the prey (x) and predator
Human-dominated ecosystems such as in South Florida's Everglades region are greatly affected by societal actions and choices, and efforts to restore degraded ecosystems must take into account the societal drivers of ecosystem change. A conceptual model of societal-ecological interactions within the region illustrates connections between major societal drivers, such as water management and land use, and ecological stressors, such as
Christine C. Harwell; Christopher W. Deren; George H. Snyder; William D. Solecki; James Wilson; Mark A. Harwell
The development and application of energy technologies for all aspects from generation to storage have improved dramatically with the advent of advanced computational tools, particularly modeling and simulation. Modeling and simulation are not new to energy technology development, and have been used extensively ever since the first commercial computers were available. However, recent advances in computing power and access have broadened the extent and use, and, through increased fidelity (i.e., accuracy) of the models due to greatly enhanced computing power, the increased reliance on modeling and simulation has shifted the balance point between modeling and experimentation. The complex nature of energy technologies has motivated researchers to use these tools to understand better performance, reliability and cost issues related to energy. The tools originated in sciences such as the strength of materials (nuclear reactor containment vessels); physics, heat transfer and fluid flow (oil production); chemistry, physics, and electronics (photovoltaics); and geosciences and fluid flow (oil exploration and reservoir storage). Other tools include mathematics, such as statistics, for assessing project risks. This paper describes a few advancements made possible by these tools and explores the benefits and costs of their use, particularly as they relate to the acceleration of energy technology development. The computational complexity ranges from basic spreadsheets to complex numerical simulations using hardware ranging from personal computers (PCs) to Cray computers. In all cases, the benefits of using modeling and simulation relate to lower risks, accelerated technology development, or lower cost projects.
The simulation of monsoons, in particular the Indian summer monsoon, has proven to be a critical test of a general circulation model`s ability to simulate tropical climate and variability. The Monsoon Numerical Experimentation Group has begun to address questions regarding the predictability of monsoon extremes, in particular conditions associated with El Nino and La Nina conditions that tend to be associated with drought and flood conditions over the Indian subcontinent, through a series of seasonal integrations using analyzed initial conditions from successive days in 1987 and 1988. In this paper the authors present an analysis of simulations associated with the Atmospheric Model Intercomparison Project (AMIP), a coordinated effort to simulate the 1979--1988 decade using standardized boundary conditions with approximately 30 atmospheric general circulation models. The 13 models analyzed to date are listed. Using monthly mean data from these simulations they have calculated indices of precipitation and wind shear in an effort to access the performance of the models over the course of the AMIP decade.
Sperber, K.R. [Lawrence Livermore National Lab., CA (United States). Program for Climate Model Diagnosis and Intercomparison; Palmer, T.N. [European Centre for Medium-Range Weather Forecasts, Reading (United Kingdom)
Metabolic and energetic efficiency, and hence fitness of organisms to survive, should be maximal in their habitats. This tenet of evolutionary biology invalidates the linear-nothreshold (LNT) model for the risk consequences of environmental agents. Hormesis in response to selection for maximum metabolic and energetic efficiency, or minimum metabolic imbalance, to adapt to a stressed world dominated by oxidative stress should therefore be universal. Radiation hormetic zones extending substantially beyond common background levels, can be explained by metabolic interactions among multiple abiotic stresses. Demographic and experimental data are mainly in accord with this expectation. Therefore, non-linearity becomes the primary model for assessing risks from low-dose ionizing radiation. This is the evolutionary imperative upon which risk assessment for radiation should be based.
. A class of truncated unimodal discrete-time single species models for which low or high densities result in extinction in\\u000a the following generation are considered. A classification of the dynamics of these maps into five types is proven: (i) extinction\\u000a in finite time for all initial densities, (ii) semistability in which all orbits tend toward the origin or a semi-stable
Model systems can facilitate and focus research efforts but ill-chosen or inapt ones can distract or impede scientific progress. In this Opinion article, we pose the question: how can the literature provide appropriate general conclusions if the model systems upon which the literature is based are unrepresentative of the relevant biological diversity? A good example of this problem is the endophyte-grass symbiosis, which is considered to be a classic example of mutualistic interactions. Meta-analysis of the primary literature demonstrates that the conceptual framework for endophyte-grass interactions has largely been based on endophyte-plant-herbivore studies of two agricultural grass species, tall fescue and perennial ryegrass. Consistent with conventional wisdom, the meta-analysis indicates that endophytes slightly increase grass resistance to herbivores. By contrast, endophytes appear not to affect plant performance or competitive ability. The positive effects of endophytes appear to be dependent on genetic variation in the host and endophyte, and on nutrient availability in soils. Thus, the agronomic grass model systems fail to capture the breadth of variability inherent in wild grass-endophyte populations and communities. PMID:16890473
Saikkonen, Kari; Lehtonen, Päivi; Helander, Marjo; Koricheva, Julia; Faeth, Stanley H
The Oil Market Simulation (OMS) model is a LOTUS 1-2-3 spreadsheet that simulates the world oil market. OMS is an annual model that projects the world oil market through the year 2010 from a data base that begins in 1979. The geographic coverage includes all market economies, with net imports from the centrally planned economies taken as an assumption. The model estimates the effects of price changes on oil supply and demand and computes an oil price path over time that allows supply and demand to remain in balance within the market economies area as a whole. 2 figs., 2 tabs.
The Oil Market Simulation (OMS) model is a LOTUS 1-2-3 spreadsheet that simulates the world oil market. OMS is an annual model that projects the world oil market through the year 2010 from a data base that begins in 1979. The geographic coverage includes all market economies, with net imports from the centrally planned economies taken as an assumption. The model estimates the effects of price changes an oil supply and demand and computes an oil price path over time that allows supply and demand to remain in balance within the market economies area as a whole.
Five algorithms producing daily solar radiation surrogates using daily temperatures and rainfall were evaluated using measured solar radiation data for seven U.S. locations. The algorithms were compared both in terms of accuracy of daily solar radiation estimates and terms of response when used in a plant growth simulationmodel (CERES-wheat). Requirements for accuracy of solar radiation for plant growth simulationmodels are discussed. One algorithm is recommended as being best suited for use in these models when neither measured nor satellite estimated solar radiation values are available.
Techniques are presented for modeling and randomly sampling many of the multivariate probabilistic input processes that drive discrete-event simulation experiments. Emphasis is given to bivariate and trivariate extensions of the univariate beta, Johnson, and Bézier dist ribution families because of the flexibility of these families to model a wide range of shapes for the marginal distributions while also representing the
Michael E. Kuhl; Julie S. Ivy; Emily K. Lada; Natalie M. Steiger; Mary Ann Flanigan Wagner; James R. Wilson
Dielectric elastomers are used as base material for so-called electroactive polymer (EAP) actuators. A procedure and a specific constitutive model (for the acrylic elastomer VHB 4910) are presented in this work for finite element modeling and simulation of dielectric elastomer actuators of general shape and set-up. The Yeoh strain energy potential and the Prony series are used for describing the
This paper intends to present a model of power transformers used in simulation of power inverters. Electromagnetic induction refers to the phenomenon by witch electric current is generated in a closed circuit by the fluctuation of current in another circuit placed next to it. For modeling of power transformers, we implemented a Matlab software, based on mathematical equations who describe
This paper presents a new landscape management model using a simulated annealing approach. The model is capable of achieving target landscape structure, in the form of composition and configuration objectives, in a near optimal fashion by spatially and temporally scheduling treatment interventions. Management objectives and constraints are identified in an objective function. Penalty cost functions for each objective establish common
A dynamic model of a centrifugal compressor capable of system simulation in the virtual test bed (VTB) computational environment is presented. The model is based on first principles, i.e. the dynamic performance including the losses is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. In this study, the compressor losses, such as incidence and
This paper presents a model for studying the impact of individual agents characteristics in emergent groups, on the evacuation efficiency as a result of local interactions. We used the physically based model of crowd simulation proposed by Helbing (6) and generalized it in order to deal with different individualities for agent and group behaviors. In addition, we present a framework
Adriana Braun; Soraia Raupp Musse; Luiz Paulo Luna De Oliveira; Bardo E. J. Bodmann
This panel session is to discuss the issues and current research in hierarchical modeling for discrctc event simulation. Three academic researchers are to briefly describe their research in hierarchical modeling and the issues and one industrial practitioner will present the issues from a user’s perspective.
Robert G. Sargent; Joe H. Mize; David H. Withers; Bernard P. Zeigler
This panel session is 1.0 discuss the issucs and current research in hierarchical modeling for discrete event simulation. Three academic researchcrs are to briefly describe their research in hicrarchical modeling and the issues and one industrial practitioncr will present the issues from a user's perspcctivc. 1 BACKGROUND
R. G. Sargent; J. H. Mize; D. H. Withers; B. P. Zeigler
A new modeling approach for large-eddy simulation (LES) is obtained by combining a ``regularization principle'' with an explicit filter and its inversion. This regularization approach allows a systematic derivation of the implied subgrid model, which resolves the closure problem. The central role of the filter in LES is fully restored, i.e., both the interpretation of LES predictions in terms of
This paper introduces a method for handling deformation in interactive, real time computer graphics simulations which involve deformable objects and require a high degree of visual realism. Our proposal, the virtual structure, is a “divide and conquer” approach, which combines a novel physical model with a geometric modelling utilizes the theory of elasticity and Newtonian mechanics, applied by a numerical
This paper documents the use of recently developed symbolic software for modeling of a US Army M113 armoured personnel carrier and numerical simulation of the generated nonlinear ordinary differential equations of motion. A brief discussion of the symbolic software used for modeling, analysis, and control system design of multiple body systems is presented. This software is used to create a
Eric Salter; Chris LaVigna; Mike Mattice; Mary Devito; Robert Testa
Although the systematic utility of ecological niche modeling is generally well known (e.g., concerning the recognition and discovery of areas of endemism for biogeographic analyses), there has been little discussion of applications concerning species delimitation, and to date, no empirical evaluation has been conducted. However, ecological niche modeling can provide compelling evidence for allopatry between populations, and can also detect divergent ecological niches between candidate species. Here we present results for two taxonomically problematic groups of Phelsuma day geckos from Madagascar, where we integrate ecological niche modeling with mitochondrial DNA and morphological data to evaluate species limits. Despite relatively modest levels of genetic and morphological divergence, for both species groups we find divergent ecological niches between closely related species and parapatric ecological niche models. Niche models based on the new species limits provide a better fit to the known distribution than models based upon the combined (lumped) species limits. Based on these results, we elevate three subspecies of Phelsuma madagascariensis to species rank and describe a new species of Phelsuma from the P. dubia species group. Our phylogeny continues to support a major endemic radiation of Phelsuma in Madagascar, with dispersals to Pemba Island and the Mascarene Islands. We conclude that ecological niche modeling offers great potential for species delimitation, especially for taxonomic groups exhibiting low vagility and localized endemism and for groups with more poorly known distributions. In particular, niche modeling should be especially sensitive for detecting recent parapatric speciation driven by ecological divergence, when the environmental gradients driving speciation are represented within the ecological niche models. PMID:18066927
Raxworthy, Christopher J; Ingram, Colleen M; Rabibisoa, Nirhy; Pearson, Richard G
The DMSS software support effort enhanced the capabilities and value of DMSS by accomplishing the following four objectives: (1) Addition of VATS/Pave Tack and Maverick Missile models; (2) Enhancing the existing software; (3) Creating meaningful, up-to-da...
This paper is the first of two describing the conclusions from a study to determine the state of the art in timber harvesting computer simulationmodeling. Five models were evaluated -- Forest Harvesting SimulationModel (FHSM), Full Tree Field Chipping (FTFC), Harvesting System Simulator (HSS), Simulation Applied to Logging Systems (SAPLOS), and Timber Harvesting and Transport Simulator (THATS) -- for their potential use in southern forest harvesting operations. In Part I, modeling characteristics and overall model philosophy are identified and illustrated. This includes a detailed discussion of the wood flow process in each model, accounting strategies for productive/non-productive times, performance variables, and the different types of harvesting systems modelable. In Part II we discuss user implementation problems. Those dealt with in detail are: What questions can be asked of the model. What are the modeling tradeoffs, and how do they impact on the analysis. What are the computer skills necessary to effectively work with the model. What computer support is needed. Are the models operational. The results provide a good picture of the state of the art in timber harvesting computer simulation. Much learning has occurred in the generation of these models, and many modeling and implementation problems have been uncovered, some of which remain unsolved. Hence, the user needs to examine closely the model and the intended application so that results will represent usable, valid data. It is recommended that the development of timber harvesting computer simulationmodeling continue, so that existing and proposed timber harvesting strategies can be adequately evaluated. A set of design criteria are proposed. (Refs. 21).
This paper introduces control system design based softwares, SIMNON and MATLAB/SIMULINK, for power electronics system simulation. A complete power electronics system typically consists of a rectifier bridge along with its smoothing capacitor, an inverter, and a motor. The system components, featuring discrete or continuous, linear or nonlinear, are modeled in mathematical equations. Inverter control methods,such as pulse-width-modulation and hysteresis current control, are expressed in either computer algorithms or digital circuits. After describing component models and control methods, computer programs are then developed for complete systems simulation. Simulation results are mainly used for studying system performances, such as input and output current harmonics, torque ripples, and speed responses. Key computer programs and simulation results are demonstrated for educational purposes.
There is increasing focus on the model development aspect of systems simulation, termed “Model Engineering”. Current software development tools consist primarily of CASE tools with simulation extensions or simulation tools with model-building extensions. The need for a Computer-Aided SimulationModel Engineering (CASME) environment is identified and discussed. In particular, a CASME environment should support a model building process based on
Most of our knowledge about avian haemosporidian parasites comes from the Hawaiian archipelago, where recently introduced Plasmodiumrelictum has contributed to the extinction of many endemic avian species. While the ecology of invasive malaria is reasonably understood, the ecology of endemic haemosporidian infection in mainland systems is poorly understood, even though it is the rule rather than the exception. We develop a mathematical model to explore and identify the ecological factors that most influence transmission of the common avian parasite, Leucocytozoonfringillinarum (Apicomplexa). The model was parameterized from White-crowned Sparrow (Zonotrichialeucophrys) and S. silvestre / craigi black fly populations breeding in an alpine ecosystem. We identify and examine the importance of altricial nestlings, the seasonal relapse of infected birds for parasite persistence across breeding seasons, and potential impacts of seasonal changes in black fly emergence on parasite prevalence in a high elevation temperate system. We also use the model to identify and estimate the parameters most influencing transmission dynamics. Our analysis found that relapse of adult birds and young of the year birds were crucial for parasite persistence across multiple seasons. However, distinguishing between nude nestlings and feathered young of the year was unnecessary. Finally, due to model sensitivity to many black fly parameters, parasite prevalence and sparrow recruitment may be most affected by seasonal changes in environmental temperature driving shifts in black fly emergence and gonotrophic cycles. PMID:24073288
Murdock, Courtney C; Foufopoulos, Johannes; Simon, Carl P
Most of our knowledge about avian haemosporidian parasites comes from the Hawaiian archipelago, where recently introduced Plasmodiumrelictum has contributed to the extinction of many endemic avian species. While the ecology of invasive malaria is reasonably understood, the ecology of endemic haemosporidian infection in mainland systems is poorly understood, even though it is the rule rather than the exception. We develop a mathematical model to explore and identify the ecological factors that most influence transmission of the common avian parasite, Leucocytozoonfringillinarum (Apicomplexa). The model was parameterized from White-crowned Sparrow (Zonotrichialeucophrys) and S. silvestre / craigi black fly populations breeding in an alpine ecosystem. We identify and examine the importance of altricial nestlings, the seasonal relapse of infected birds for parasite persistence across breeding seasons, and potential impacts of seasonal changes in black fly emergence on parasite prevalence in a high elevation temperate system. We also use the model to identify and estimate the parameters most influencing transmission dynamics. Our analysis found that relapse of adult birds and young of the year birds were crucial for parasite persistence across multiple seasons. However, distinguishing between nude nestlings and feathered young of the year was unnecessary. Finally, due to model sensitivity to many black fly parameters, parasite prevalence and sparrow recruitment may be most affected by seasonal changes in environmental temperature driving shifts in black fly emergence and gonotrophic cycles.
Murdock, Courtney C.; Foufopoulos, Johannes; Simon, Carl P.
The observed scaling invariance properties of rainfall time series have often been put forward to justify the choice of multifractal (scaling) models for rainfall stochastic modelling. These models are nevertheless seldom validated on real hydrological applications. Two types of multifractal models - the first one with a Log-Poisson generator and the second one with a uniform generator - were calibrated on a 8 year point rainfall series with a five minute time step. The results obtained with the rainfall series simulated with these models on two hydrological applications (the computation of intensity-duration-frequency, IDF, curves and the conception of a urban drainage storage volume) were compared with those obtained with the original measured rainfall series. The disagreements reveal some limitations of the multifractal models. On the one hand, using the vocabulary of the multifractalists, the models are calibrated on the basis of the statistical properties of the simulated undressed series while the IDF curves are computed on the dressed series. The statistical properties of both types of series clearly differ if a canonical model is used : here the model with the Log-Poisson generator. On the other hand, the optimal dimensions of the storage volume depend on the shape of the hyetographs. The discordances between the volumes obtained with the simulated or measured rainfall series indicate that the temporal structure of the simulated rainfall intensity series (i.e. the shapes of the simulated hyetographs) are not comparable with the one of the measured series. As a conclusion, multifractal models appear to reproduce accuratly only some of the properties of the real measured series. Their appropriateness should not be a priori asserted but verified for each considered application.
The numerical simulation has become an indispensable tool in the design, production and process set up of deep drawn parts.\\u000a The advantages of these tools are nowadays well known. If the numerical model correctly describes both the technological procedure\\u000a and process parameters, the use of numerical simulation allows to save time, money and effort. One of the challenges to guarantee
For the first time, we combine concepts of theoretical food web modeling, the metabolic theory of ecology, and ecological stoichiometry with the use of functional trait databases to predict the coexistence of invertebrate taxa in streams. We developed a mechanistic model that describes growth, death, and respiration of different taxa dependent on various environmental influence factors to estimate survival or extinction. Parameter and input uncertainty is propagated to model results. Such a model is needed to test our current quantitative understanding of ecosystem structure and function and to predict effects of anthropogenic impacts and restoration efforts. The model was tested using macroinvertebrate monitoring data from a catchment of the Swiss Plateau. Even without fitting model parameters, the model is able to represent key patterns of the coexistence structure of invertebrates at sites varying in external conditions (litter input, shading, water quality). This confirms the suitability of the model concept. More comprehensive testing and resulting model adaptations will further increase the predictive accuracy of the model. PMID:23691656
Construction of mathematical simulationmodels helps to organize current information and extend inferences from available\\u000a data. During the past two decades, microbial ecology has undergone rapid developments in both quantity and quality of available\\u000a data. In particular, considerable advances have been made in our knowledge of microbial food web dynamics in the Duplin River\\u000a watershed at Sapelo Island, Georgia. Here
Device simulation has two main purposes: to understand and to depict the physical processes in the interior of a device, and\\u000a to make reliable predictions of the behavior of the next device generation. Towards these goals, the quality of the implemented\\u000a physical models is decisive, forcing heuristic fit models to be replaced by “first-principle”-based models. Since transport\\u000a schemes using moments
The relative risk model (RRM) was applied in regional ecological risk assessments successfully. In this study, the RRM was\\u000a developed through increasing the data of risk source and introducing the source–stressor–habitat exposure filter (SSH), the\\u000a endpoint–habitat exposure filter (EH) and the stressor–endpoint effect filter (SE) to reflect the meaning of exposure and\\u000a effect more explicit. Water environment which include water
Jingling LiuQiuying ChenYongli Li; Qiuying Chen; Yongli Li
All women of childbearing age who are capable of becoming pregnant should consume 0.4 mg/400 microg of folic acid daily. Folic acid decreases the incidence of neural tube defects in newborns. Despite continued public health initiatives, many women still do not consume the recommended daily requirement. This article analyzes the use of the social ecologicalmodel in folic acid public health initiatives and emphasizes assessing the outcomes of such initiatives. PMID:16282224
Quinn, Lisa A; Thompson, Sharon J; Ott, M Katherine
Little is known about the social and contextual correlates (e.g., social norms, environment, social networks, and organizational\\u000a support) influencing the adoption and maintenance of regular physical activity among minority and underserved populations.\\u000a The purpose of this review was to apply the social ecologicalmodel to better understand physical activity among African American\\u000a women. A review of the literature pertaining to
The ecologicalmodel of Carel van Schaik provides clear predictions for female-female relationships in relation to scramble or contest within-group competition and contest between-group competition. These predictions were applied to data from a 12-year field study on Hanuman langurs (Presbytis entellus) that ranged freely around Jodhpur (India). It appears that hierarchical relationships between females (unstable, inconsistent, individualistic, with low rates
\\u000a We describe the fundamentals and applications of trophic models of ecological systems and show how a simple mass balance approach\\u000a of the early 1980s was further developed into a very advanced complex software package, freely available on the internet (Ecopath\\u000a with Ecosim, EwE, http:\\/\\/www.ecopath.org). Through its three decades of evolution, the approach became increasingly popular, with over three hundred Ecopath
\\u000a This is part of an ongoing exploration of incorporating fuzzy logic into spatially explicit, individual-based ecologicalmodels\\u000a of dispersal. Following the theoretical discussion of Robinson (2002), a prototypical model of small mammal dispersal behavior\\u000a was used to demonstrate how the fuzzy control of dispersal agents could be implemented (Robinson and Graniero 2005a). The\\u000a implementation showed how the Extensible Component Objects
Morgantown Energy Technology Center is developing an advanced moving-bed gasifier, which is the centerpiece of the Integrated Gasifier Combined-Cycle (IGCC) system, with the features of good efficiency, low cost, and minimal environmental impact. A mathematical model of the gasifier, the METC-Gasifier Advanced Simulation (MGAS) model, has been developed for the analysis and design of advanced gasifiers and other moving-bed gasifiers. This report contains the technical and the user manuals of the MGAS model. The MGAS model can describe the transient operation of coflow, counterflow, or fixed-bed gasifiers. It is a one-dimensional model and can simulate the addition and withdrawal of gas and solids at multiple locations in the bed, a feature essential for simulating beds with recycle. The model describes the reactor in terms of a gas phase and a solids (coal or char) phase. These phases may exist at different temperatures. The model considers several combustion, gasification, and initial stage reactions. The model consists of a set of mass balances for 14 gas species and three coal (pseudo-) species and energy balances for the gas and the solids phases. The resulting partial differential equations are solved using a finite difference technique.
Syamlal, M. [EG and G Washington Analytical Services Center, Inc., Morgantown, WV (United States); Bissett, L.A. [USDOE Morgantown Energy Technology Center, WV (United States)
G. I. Taylor showed that dynamic material properties could be deduced from the impact of a projectile against a rigid boundary. The Taylor anvil test became very useful with the advent of numerical simulations and has been used to infer and/or to validate material constitutive constants. A new experimental facility has been developed to conduct Taylor anvil impacts to support validation of constitutive constants used in simulations. Typically, numerical simulations are conducted assuming 2-D cylindrical symmetry, but such computations cannot hope to capture the damage observed in higher velocity experiments. A computational study was initiated to examine the ability to simulate damage and subsequent deformation of the Taylor specimens. Three-dimensional simulations, using the Johnson-Cook damage model, were conducted with the nonlinear Eulerian wavecode CTH. The results of the simulations are compared to experimental deformations of 6061-T6 aluminum specimens as a function of impact velocity, and conclusions regarding the ability to simulate fracture and reproduce the observed deformations are summarized.
Anderson, C. E., Jr.; Chocron, I. S.; Nicholls, A. E.
The Joint Forces Air Component Commander (JFACC) in military air operations controls the allocation of resources (wings, squadrons, air defense systems, AWACS) to different geographical locations in the theater of operations. The JFACC mission is to define a sequence of tasks for the aerospace systems at each location, and providing feedback control for the execution of these tasks in the presence of uncertainties and a hostile enemy. Honeywell Labs has been developing an innovative method for control of military air operations. The novel model predictive control (MPC) method extends the models and optimization algorithms utilized in traditional model predictive control systems. The enhancements include a tasking controller and, in a joint effort with USC, a probabilistic threat/survival map indicating high threat regions for aircraft and suggesting optimal routes to avoid these regions. A simulation/modeling environment using objected-oriented methodologies has been developed to serve as an aide to demonstrate the value of MPC and facilitate its development. The simulation/modeling environment is based on an open architecture that enables the integration, evaluation, and implementation of different control approaches. The simulation offers a graphical user interface displaying the battlefield, the control performance, and a probability map displaying high threat regions. This paper describes the features of the different control approaches and their integration into the simulation environment.
We simulated male gypsy moth flight phenology for the location of 1371 weather stations east of 100° W longitude and north of 35° N latitude in North America. The output of these simulations, based on average weather conditions from 1961 to 1990, was submitted to two map-interpolation methods: multiple regression and universal kriging. Multiple regression was found to be as accurate as universal kriging and demands less computing power. A map of the date of peak male gypsy moth flight was generated by universal kriging. This map itself constitutes a useful pest-management planning tool; in addition, the map delineates the potential range of the gypsy moth based on its seasonality at the northern edge of its current distribution in eastern North America. The simulation and map-interpolation methods described in this paper thus constitute an interesting approach to the study and monitoring of the ecological impacts of climate change and shifts in land-use patterns at the sub-continental level.
The report documents the development of a conceptual model for assessing the ecological risk to the water quality function (WQF) of bottomland hardwood riparian ecosystems (BHRE) in the Tifton-Vidalia upland (TVU) ecoregion of Georgia. Previous research h...
Sea level rise (SLR) has the potential to affect a variety of coastal habitats with a myriad of deleterious ecological effects and to overwhelm human settlements along the coast. SLR should be given serious consideration when more than half of the U.S. population lives within 50 miles of the coast. SLR effects will be felt along coastal beaches and in estuarine waters, with consequences to barrier islands, submerged aquatic vegetation beds, sand and mud flats, oyster reefs, and tidal and freshwater wetlands. Managers of these coastal resources must be aware of potential consequences of SLR and adjust their plans accordingly to protect and preserve the resources under their care. The Gulf Coast provides critical habitats for a majority of the commercially important species in the Gulf of Mexico, which depend on inshore waters for either permanent residence or nursery area. The ecosystem services provided by these coastal habitats are at risk from rising sea level. Our team will assess the risk to coasts and coastal habitats from SLR in a 5-year project. We will apply existing models of circulation and transport from the watershed to the sea. The ultimate prediction will be of sediment loadings to the estuary as a result of overland flow, shoreline and barrier island erosion, and salinity transport, all of which will be used to model the evolution of intertidal marshes (MEM II). Over the five-year course of our research we will be simulating hydrodynamics and transport for all three NERRS reserves, including: Apalachicola, Weeks Bay and Grand Bay. The project will result in products whereby managers will be able to assess marshes, oyster reefs, submerged aquatic vegetation, predict wetland stability and indentify restoration locations for marsh and oyster habitats. In addition, we will produce Decision Support tools that will enable managers to predict future coastal erosion rates for management-specified shorelines. Project outcomes will enable the management community to prioritize risk management strategies, reformulate set back requirements, improve guidelines for construction of breakwaters and other coastal infrastructure, and assess water resources impacts and protection needs.
Hagen, S. C.; Lewis, G.; Bartel, R.; Batten, B.; Huang, W.; Morris, J.; Slinn, D. N.; Sparks, J.; Walters, L.; Wang, D.; Weishampel, J.; Yeh, G.
Modern ecology recognizes that modelling systems across scales and at multiple levels—especially to link population and ecosystem dynamics to individual adaptive behaviour—is essential for making the science predictive. ‘Pattern-oriented modelling’ (POM) is a strategy for doing just this. POM is the multi-criteria design, selection and calibration of models of complex systems. POM starts with identifying a set of patterns observed at multiple scales and levels that characterize a system with respect to the particular problem being modelled; a model from which the patterns emerge should contain the right mechanisms to address the problem. These patterns are then used to (i) determine what scales, entities, variables and processes the model needs, (ii) test and select submodels to represent key low-level processes such as adaptive behaviour, and (iii) find useful parameter values during calibration. Patterns are already often used in these ways, but a mini-review of applications of POM confirms that making the selection and use of patterns more explicit and rigorous can facilitate the development of models with the right level of complexity to understand ecological systems and predict their response to novel conditions.
Relations between political violence and child adjustment are matters of international concern. Past research demonstrates the significance of community, family, and child psychological processes in child adjustment, supporting study of interrelations between multiple social ecological factors and child adjustment in contexts of political violence. Testing a social ecologicalmodel, 300 mothers and their children (M = 12.28 years, SD = 1.77) from Catholic and Protestant working class neighborhoods in Belfast, Northern Ireland, completed measures of community discord, family relations, and children's regulatory processes (i.e., emotional security) and outcomes. Historical political violence in neighborhoods based on objective records (i.e., politically motivated deaths) were related to family members' reports of current sectarian antisocial behavior and nonsectarian antisocial behavior. Interparental conflict and parental monitoring and children's emotional security about both the community and family contributed to explanatory pathways for relations between sectarian antisocial behavior in communities and children's adjustment problems. The discussion evaluates support for social ecologicalmodels for relations between political violence and child adjustment and its implications for understanding relations in other parts of the world. PMID:20423550
Cummings, E Mark; Merrilees, Christine E; Schermerhorn, Alice C; Goeke-Morey, Marcie C; Shirlow, Peter; Cairns, Ed
Relations between political violence and child adjustment are matters of international concern. Past research demonstrates the significance of community, family and child psychological processes in child adjustment, supporting study of inter-relations between multiple social ecological factors and child adjustment in contexts of political violence. Testing a social ecologicalmodel, 300 mothers and their children (M= 12.28 years, SD = 1.77) from Catholic and Protestant working class neighborhoods in Belfast, Northern Ireland completed measures of community discord, family relations, and children’s regulatory processes (i.e., emotional security) and outcomes. Historical political violence in neighborhoods based on objective records (i.e., politically motivated deaths) were related to family members’ reports of current sectarian and non-sectarian antisocial behavior. Interparental conflict and parental monitoring and children’s emotional security about both the community and family contributed to explanatory pathways for relations between sectarian antisocial behavior in communities and children’s adjustment problems. The discussion evaluates support for social ecologicalmodels for relations between political violence and child adjustment and its implications for understanding relations in other parts of the world.
Cummings, E. Mark; Merrilees, Christine E.; Schermerhorn, Alice C.; Goeke-Morey, Marcie C.; Shirlow, Peter; Cairns, Ed
As most biologists are probably aware, technological advances in molecular biology during the last few years have opened up possibilities to rapidly generate large-scale sequencing data from non-model organisms at a reasonable cost. In an era when virtually any study organism can ‘go genomic', it is worthwhile to review how this may impact molecular ecology. The first studies to put the next generation sequencing (NGS) to the test in ecologically well-characterized species without previous genome information were published in 2007 and the beginning of 2008. Since then several studies have followed in their footsteps, and a large number are undoubtedly under way. This review focuses on how NGS has been, and can be, applied to ecological, population genetic and conservation genetic studies of non-model species, in which there is no (or very limited) genomic resources. Our aim is to draw attention to the various possibilities that are opening up using the new technologies, but we also highlight some of the pitfalls and drawbacks with these methods. We will try to provide a snapshot of the current state of the art for this rapidly advancing and expanding field of research and give some likely directions for future developments.
Significant warming has been observed in every ocean, yet our ability to predict the consequences of oceanic warming on marine biodiversity remains poor. Experiments have been severely limited because, until now, it has not been possible to manipulate seawater temperature in a consistent manner across a range of marine habitats. We constructed a “hot-plate” system to directly examine ecological responses to elevated seawater temperature in a subtidal marine system. The substratum available for colonisation and overlying seawater boundary layer were warmed for 36 days, which resulted in greater biomass of marine organisms and a doubling of space coverage by a dominant colonial ascidian. The “hot-plate” system will facilitate complex manipulations of temperature and multiple stressors in the field to provide valuable information on the response of individuals, populations and communities to environmental change in any aquatic habitat.
Smale, Dan A.; Wernberg, Thomas; Peck, Lloyd S.; Barnes, David K. A.
A crop growth simulationmodel has been used to assess the potential for maize production in Zambia under various crop management systems, ranging from low input subsistence farming to large scale commercial farming using high input cropping technologies....
J. Huygen C. A. van Diepen C. H. van Immerzeel H. van Keulen F. de Koning
We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios, and the small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.
Devanathan, Ramaswami; Van Brutzel, Laurent; Chartier, Alan; Gueneau, Christine; Mattsson, Ann E.; Tikare, Veena; Bartel, Timothy; Besmann, T. M.; Stan, Marius; Van Uffelen, Paul
We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios and small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.
Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Van Brutzel, Laurent [LSCE/CEA, Gif-sur-Yvette, France; Chartier, Alain [LSCE/CEA, Gif-sur-Yvette, France; Christine, Gueneau [LSCE/CEA, Gif-sur-Yvette, France; Mattsson, Ann [Sandia National Laboratories (SNL); Tikare, Veena [Sandia National Laboratories (SNL); Bartel, Timothy [Sandia National Laboratories (SNL); Besmann, Theodore M [ORNL; Stan, Marius [Los Alamos National Laboratory (LANL); Van Uffelen, Paul [Institute for Transuranium Elements, Germany
This paper presents a dynamic simulationmodel for a hybrid electric scooter (HES) designed by NPUST in Taiwan. The HES is built in a parallel hybrid configuration with a 24 V 370 W auxiliary power electric motor, a 24 V 600 W generator, a 24 V 15 AH battery, and an electronically controlled fuel injection internal combustion engine (ICE). Because
The standard Penna ageing model with sexual reproduction is enlarged by adding additional bit-strings for love: Marriage happens only if the male love strings are sufficiently different from the female ones. We simulate at what level of required difference the population dies out.
Stauffer, Dietrich; Cebrat, Stanis?aw; Penna, T. J. P.; Sousa, A. O.
The interaction of particles, drops, and bubbles with a fluid (gas or liquid) is important in a number of engineering problems. The present works seeks to extend the understanding of these interactions through numerical simulation. To model many of these relevant flows, it is often important to consider finite Reynolds number effects on drag, lift, torque and history force. Thus,
This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM&S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment to providing
David A. Dixon; Bruce C. Garrett; Tp Straatsma; Donald R. Jones; Ronald S. Studham; Robert J. Harrison; Jeffrey A. Nichols
This annual report describes the 2000 research accomplishments for the Theory, Modeling, and Simulation (TM and S) directorate, one of the six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). EMSL is a U.S. Department of Energy (DOE) national scientific user facility and is the centerpiece of the DOE commitment
David A Dixon; Bruce C Garrett; TP Straatsma; Donald R Jones; Scott Studham; Robert J Harrison; Jeffrey A Nichols
This is the final report covering progress on a two year research effort towards the development of basic technology for adaptive modeling and real-time computer simulation to support decision-making in a number of critical planning situations that arise ...
This three-volume report describes the development of a water supply simulationmodel (WSSM), a system of computer programs that allows for a systematic evaluation of the physical and economic characteristics of a water distribution system in a spatial framework. The WSSM concept...
The resurgence of airships has created a need for dynamics models and simulation capabilities of these lighter-than-air vehicles. The focus of this thesis is a theoretical framework that integrates the flight dynamics, structural dynamics, aerostatics and aerodynamics of flexible airships. The study begins with a dynamics model based on a rigid-body assumption. A comprehensive computation of aerodynamic effects is presented,
This paper deals with the modeling and simulation of system-wide transients in LMFBRs. Unprotected events (i.e., the presumption of failure of the plant protection system) leading to core-melt are not considered in this paper. The existing computational capabilities in the area of protected transients in the US are noted. Various physical and numerical approximations that are made in these codes are discussed. Finally, the future direction in the area of model verification and improvements is discussed.
Agrawal, A.K.; Khatib-Rahbar, M.; Curtis, R.T.; Hetrick, D.L.; Girijashankar, P.V.
A simulation conceptual model is the simulation developer's way of translating modeling requirements (i. e., what is to be represented by the simulation) into a detailed design framework (i. e., how it is to be done), from which the software, hardware, networks (in the case of distributed simulation), and systems\\/equipment that will make up the simulation can be built. Standards
Techniques and features that have been found useful for modeling and simulating intelligent multimedia communications networks are described. Key ingredients are a robust, commercially available and supported simulation language and a modeling and simulation architecture that consists of custom-designed modules of the features that clearly occur in communication network simulation. The simulation architecture used is described at length.
It has been argued that current approaches for ecological risk assessment (ERA) do not provide value relevance for risk managers and that the uncertainty in the predictions is large. One important reason for this is that current approaches are based on individual-level endpoints, but the environmental protection goals are defined on the population level. Population models may be useful tools to link the individual to the population and thus increase value relevance and reduce uncertainty. However, this requires that simple models and guidance on how to use them are made available for risk assessors. In the present study, an approach for developing simple generic models for the ERA of fish populations is presented. Fish have high ecological and economic value and are frequently used in ERA. It is, therefore, highly desirable to develop better methods for ERA of fish populations. The models were based on five types of life histories, and they were set up to be useful in a number of different management scenarios based on different environmental protection goals. A decision framework was set up for three levels of models (continuous, time limited, and varying exposure) and three levels of environmental protection. Data from previously published studies were tested for two of the environmental protection levels. The models provided maximum acceptable concentrations (MAC) that fell between the MACs of traditional ERA based on acute or chronic data, respectively. PMID:21805500
This paper illustrates the advantages of a multilevel/hierarchical approach for predictive modeling, including flexibility of model formulation, explicitly accounting for hierarchical structure in the data, and the ability to predict the outcome of new cases. As a generalization of the classical approach, the multilevel modeling approach explicitly models the hierarchical structure in the data by considering both the within- and between-group variances leading to a partial pooling of data across all levels in the hierarchy. The modeling framework provides means for incorporating variables at different spatiotemporal scales. The examples used in this paper illustrate the iterative process of model fit