The Experts below are selected from a list of 5841 Experts worldwide ranked by ideXlab platform
Otso Ovaskainen - One of the best experts on this subject based on the ideXlab platform.
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characteristic spatial and temporal scales unify models of animal movement
The American Naturalist, 2011Co-Authors: Eliezer Gurarie, Otso OvaskainenAbstract:AbstractAnimal movements have been modeled with diffusion at large scales and with more detailed movement models at smaller scales. We argue that the biologically Relevant Behavior of a wide class of movement models can be efficiently summarized with two parameters: the characteristic temporal and spatial scales of movement. We define these scales so that they describe movement Behavior both at short scales (through the velocity autocorrelation function) and at long scales (through the diffusion coefficient). We derive these scales for two types of commonly used movement models: the discrete-step correlated random walk, with either constant or random step intervals, and the continuous-time correlated velocity model. For a given set of characteristic scales, the models produce very similar trajectories and encounter rates between moving searchers and stationary targets. Thus, we argue that characteristic scales provide a unifying currency that can be used to parameterize a wide range of ecological phenomen...
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Characteristic Spatial and Temporal Scales Unify Models of Animal Movement
The American Naturalist, 2011Co-Authors: Eliezer Gurarie, Otso OvaskainenAbstract:Animal movements have been modeled with diffusion at large scales and with more detailed movement models at smaller scales. We argue that the biologically Relevant Behavior of a wide class of movement models can be efficiently summarized with two parameters: the characteristic temporal and spatial scales of movement. We define these scales so that they describe movement Behavior both at short scales (through the velocity autocorrelation function) and at long scales (through the diffusion coefficient). We derive these scales for two types of commonly used movement models: the discrete-step correlated random walk, with either constant or random step intervals, and the continuous-time correlated velocity model. For a given set of characteristic scales, the models produce very similar trajectories and encounter rates between moving searchers and stationary targets. Thus, we argue that characteristic scales provide a unifying currency that can be used to parameterize a wide range of ecological phenomena related to movement.
Eliezer Gurarie - One of the best experts on this subject based on the ideXlab platform.
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characteristic spatial and temporal scales unify models of animal movement
The American Naturalist, 2011Co-Authors: Eliezer Gurarie, Otso OvaskainenAbstract:AbstractAnimal movements have been modeled with diffusion at large scales and with more detailed movement models at smaller scales. We argue that the biologically Relevant Behavior of a wide class of movement models can be efficiently summarized with two parameters: the characteristic temporal and spatial scales of movement. We define these scales so that they describe movement Behavior both at short scales (through the velocity autocorrelation function) and at long scales (through the diffusion coefficient). We derive these scales for two types of commonly used movement models: the discrete-step correlated random walk, with either constant or random step intervals, and the continuous-time correlated velocity model. For a given set of characteristic scales, the models produce very similar trajectories and encounter rates between moving searchers and stationary targets. Thus, we argue that characteristic scales provide a unifying currency that can be used to parameterize a wide range of ecological phenomen...
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Characteristic Spatial and Temporal Scales Unify Models of Animal Movement
The American Naturalist, 2011Co-Authors: Eliezer Gurarie, Otso OvaskainenAbstract:Animal movements have been modeled with diffusion at large scales and with more detailed movement models at smaller scales. We argue that the biologically Relevant Behavior of a wide class of movement models can be efficiently summarized with two parameters: the characteristic temporal and spatial scales of movement. We define these scales so that they describe movement Behavior both at short scales (through the velocity autocorrelation function) and at long scales (through the diffusion coefficient). We derive these scales for two types of commonly used movement models: the discrete-step correlated random walk, with either constant or random step intervals, and the continuous-time correlated velocity model. For a given set of characteristic scales, the models produce very similar trajectories and encounter rates between moving searchers and stationary targets. Thus, we argue that characteristic scales provide a unifying currency that can be used to parameterize a wide range of ecological phenomena related to movement.
Willi Mcfarland - One of the best experts on this subject based on the ideXlab platform.
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socioeconomic position and hiv risk Relevant Behavior among lower income heterosexuals in san francisco
Aids and Behavior, 2011Co-Authors: Michael P Arnold, Raymond H Fisher, Willi McfarlandAbstract:We assess whether there is evidence of an association between socioeconomic position (SEP) and HIV risk-Relevant Behavior among lower income heterosexual men and women in San Francisco. Respondents residing in low income areas with high heterosexual AIDS case burden in San Francisco were recruited through long-chain referral in 2006–2007. Risk measures included unprotected vaginal intercourse, concurrency and exchange sex. SEP was defined as household annual income, per capita income, and employment. Analyses utilized mixed and fixed effects models. A total of 164 men and 286 women were included in the study. SEP was only significant in the case of exchange sex among men: men reporting annual income greater than $30,000 had significantly lower odds of exchange sex relative to other men. Evaluating the connection between economic status and HIV requires additional studies covering diverse populations. Future studies should focus on community economic context as well as individual SEP.
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Erratum: Socioeconomic position and HIV risk-Relevant Behavior among lower-income heterosexuals in San Francisco (AIDS and Behavior DOI: 10.1007/s10461-009-9665-4)
Aids and Behavior, 2010Co-Authors: Michael P Arnold, H. Fisher Raymond, Willi McfarlandAbstract:We assess whether there is evidence of an association between socioeconomic position (SEP) and HIV risk-Relevant Behavior among lower income heterosexual men and women in San Francisco. Respondents residing in low income areas with high heterosexual AIDS case burden in San Francisco were recruited through long-chain referral in 2006-2007. Risk measures included unprotected vaginal intercourse, concurrency and exchange sex. SEP was defined as household annual income, per capita income, and employment. Analyses utilized mixed and fixed effects models. A total of 164 men and 286 women were included in the study. SEP was only significant in the case of exchange sex among men: men reporting annual income greater than $30,000 had significantly lower odds of exchange sex relative to other men. Evaluating the connection between economic status and HIV requires additional studies covering diverse populations. Future studies should focus on community economic context as well as individual SEP.
Michael P Arnold - One of the best experts on this subject based on the ideXlab platform.
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socioeconomic position and hiv risk Relevant Behavior among lower income heterosexuals in san francisco
Aids and Behavior, 2011Co-Authors: Michael P Arnold, Raymond H Fisher, Willi McfarlandAbstract:We assess whether there is evidence of an association between socioeconomic position (SEP) and HIV risk-Relevant Behavior among lower income heterosexual men and women in San Francisco. Respondents residing in low income areas with high heterosexual AIDS case burden in San Francisco were recruited through long-chain referral in 2006–2007. Risk measures included unprotected vaginal intercourse, concurrency and exchange sex. SEP was defined as household annual income, per capita income, and employment. Analyses utilized mixed and fixed effects models. A total of 164 men and 286 women were included in the study. SEP was only significant in the case of exchange sex among men: men reporting annual income greater than $30,000 had significantly lower odds of exchange sex relative to other men. Evaluating the connection between economic status and HIV requires additional studies covering diverse populations. Future studies should focus on community economic context as well as individual SEP.
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Erratum: Socioeconomic position and HIV risk-Relevant Behavior among lower-income heterosexuals in San Francisco (AIDS and Behavior DOI: 10.1007/s10461-009-9665-4)
Aids and Behavior, 2010Co-Authors: Michael P Arnold, H. Fisher Raymond, Willi McfarlandAbstract:We assess whether there is evidence of an association between socioeconomic position (SEP) and HIV risk-Relevant Behavior among lower income heterosexual men and women in San Francisco. Respondents residing in low income areas with high heterosexual AIDS case burden in San Francisco were recruited through long-chain referral in 2006-2007. Risk measures included unprotected vaginal intercourse, concurrency and exchange sex. SEP was defined as household annual income, per capita income, and employment. Analyses utilized mixed and fixed effects models. A total of 164 men and 286 women were included in the study. SEP was only significant in the case of exchange sex among men: men reporting annual income greater than $30,000 had significantly lower odds of exchange sex relative to other men. Evaluating the connection between economic status and HIV requires additional studies covering diverse populations. Future studies should focus on community economic context as well as individual SEP.
S Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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development of a matlab simulink model of a single phase grid connected photovoltaic system
IEEE Transactions on Energy Conversion, 2009Co-Authors: Michael Ropp, S GonzalezAbstract:Because of their deployment in dispersed locations on the lowest voltage portions of the grid, photovoltaic (PV) systems pose unique challenges to power system engineers. Computer models that accurately simulate the Relevant Behavior of PV systems would thus be of high value. However, most of today's models either do not accurately model the dynamics of the maximum power point trackers (MPPTs) or anti-islanding algorithms, or they involve excessive computational overhead for this application. To address this need, a Matlab/Simulink model of a single-phase grid-connected PV inverter has been developed and experimentally tested. The development of the PV array model, the integration of the MPPT with an averaged model of the power electronics, and the Simulink implementation are described. It is experimentally demonstrated that the model works well in predicting the general Behaviors of single-phase grid-connected PV systems. This paper concludes with a discussion of the need for a full gradient-based MPPT model, as opposed to a commonly used simplified MPPT model.
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Development of a MATLAB/Simulink Model of a Single-Phase Grid-Connected Photovoltaic System
IEEE Transactions on Energy Conversion, 2009Co-Authors: Michael Ropp, S GonzalezAbstract:Because of their deployment in dispersed locations on the lowest voltage portions of the grid, photovoltaic (PV) systems pose unique challenges to power system engineers. Computer models that accurately simulate the Relevant Behavior of PV systems would thus be of high value. However, most of today's models either do not accurately model the dynamics of the maximum power point trackers (MPPTs) or anti-islanding algorithms, or they involve excessive computational overhead for this application. To address this need, a Matlab/Simulink model of a single-phase grid-connected PV inverter has been developed and experimentally tested. The development of the PV array model, the integration of the MPPT with an averaged model of the power electronics, and the Simulink implementation are described. It is experimentally demonstrated that the model works well in predicting the general Behaviors of single-phase grid-connected PV systems. This paper concludes with a discussion of the need for a full gradient-based MPPT model, as opposed to a commonly used simplified MPPT model.