Strategy selection: An introduction to the modeling challenge

Modeling the mechanisms that determine how humans and other agents choose among different behavioral and cognitive processes-be they strategies, routines, actions, or operators-represents a paramount theoretical stumbling block across disciplines, ranging from the cognitive and decision sciences to economics, biology, and machine learning. By using the cognitive and decision sciences as a case study, we provide an introduction to what is also known as the strategy selection problem. First, we explain why many researchers assume humans and other animals to come equipped with a repertoire of behavioral and cognitive processes. Second, we expose three descriptive, predictive, and prescriptive challenges that are common to all disciplines which aim to model the choice among these processes. Third, we give an overview of different approaches to strategy selection. These include cost‐benefit, ecological, learning, memory, unified, connectionist, sequential sampling, and maximization approaches. We conclude by pointing to opportunities for future research and by stressing that the selection problem is far from being resolved.

Biosensor-based diagnostics of contaminated groundwater: assessment and remediation strategy

Shallow groundwater beneath a former airfield site in southern England has been heavily contaminated with a wide range of chlorinated solvents. The feasibility of using bacterial biosensors to complement chemical analysis and enable cost-effective, and focussed sampling has been assessed as part of a site evaluation programme. Five different biosensors, three metabolic (Vibrio fischeri, Pseudomonas fluorescens 10568 and Escherichia coli HB101) and two catabolic (Pseudomonas putida TVA8 and E. coli DH5alpha), were employed to identify areas where the availability and toxicity of pollutants is of most immediate environmental concern. The biosensors used showed different sensitivities to each other and to the groundwater samples tested. There was generally a good agreement with chemical analyses. The potential efficacy of remediation strategies was explored by coupling sample manipulation to biosensor tests. Manipulation involved sparging and charcoal treatment procedures to simulate remediative engineering solutions. Sparging was sufficient at most locations. (C) 2004 Elsevier Ltd. All rights reserved.

Feasibility of using in situ fusion for the determination of Co, Cr and Mn in Portland cement by direct solid sampling graphite furnace atomic absorption spectrometry

In situ fusion on the boat-type graphite platform has been used as a sample pretreatment for the direct determination of Co, Cr and Mn in Portland cement by solid sampling graphite furnace atomic absorption spectrometry (SS-GF AAS). The 3-field Zeeman technique was adopted for background correction to decrease the sensitivity during measurements. This strategy allowed working with up to 200 mu g of sample. The in situ fusion was accomplished using 10 mu L of a flux mixture 4.0% m/v Na(2)CO(3) + 4.0% m/v ZnO + 0.1% m/v Triton (R) X-100 added over the cement sample and heated at 800 degrees C for 20 s. The resulting mould was completely dissolved with 10 mu L of 0.1% m/v HNO(3). Limits of detection were 0.11 mu g g(-1) for Co, 1.1 mu g g(-1) for Cr and 1.9 mu g g(-1) for Mn. The accuracy of the proposed method has been evaluated by the analysis of certified reference materials. The values found presented no statistically significant differences compared to the certified values (Student`s t-test, p<0.05). In general, the relative standard deviation was lower than 12% (n = 5). (C) 2009 Elsevier B.V. All rights reserved.

Direct determination of iron in sand using solid sampling graphite furnace atomic absorption spectrometry

A fast and reliable method for the direct determination of iron in sand by solid sampling graphite furnace atomic absorption spectrometry was developed. A Zeeman-effect 3-field background corrector was used to decrease the sensitivity of spectrometer measurements. This strategy allowed working with up to 200 mu g of samples, thus improving the representativity. Using samples with small particle sizes (1-50 mu m) and adding 5 mu g Pd as chemical modifier, it was possible to obtain suitable calibration curves with aqueous reference solutions. The pyrolysis and atomization temperatures for the optimized heating program were 1400 and 2500 degrees C, respectively. The characteristic mass, based on integrated absorbance, was 56 pg, and the detection limits, calculated considering the variability of 20 consecutive measurements of platform inserted without sample was 32 pg. The accuracy of the procedure was checked with the analysis of two reference materials (IPT 62 and 63). The determined concentrations were in agreement with the recommended values (95% confidence level). Five sand samples were analyzed, and a good agreement (95% confidence level) was observed using the proposed method and conventional flame atomic absorption spectrometry. The relative standard deviations were lower than 25% (n = 5). The tube and boat platform lifetimes were around 1000 and 250 heating cycles, respectively.

Strategy of specification of management areas: rice grain yield as related to soil fertility

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Diet and feeding strategy of smooth butterfly ray Gymnura micrura in northeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Improved sampling for gradient-domain metropolis light transport

We present a generalized framework for gradient-domain Metropolis rendering, and introduce three techniques to reduce sampling artifacts and variance. The first one is a heuristic weighting strategy that combines several sampling techniques to avoid outliers. The second one is an improved mapping to generate offset paths required for computing gradients. Here we leverage the properties of manifold walks in path space to cancel out singularities. Finally, the third technique introduces generalized screen space gradient kernels. This approach aligns the gradient kernels with image structures such as texture edges and geometric discontinuities to obtain sparser gradients than with the conventional gradient kernel. We implement our framework on top of an existing Metropolis sampler, and we demonstrate significant improvements in visual and numerical quality of our results compared to previous work.

The Benefits of Sampling Sports During Childhood

Sampling may promote prolonged engagement in sport by limiting physical injuries (Fraser-Thomas et al., 2005). Overtraining injuries are a concern for young athletes who specialize in one sport and engage in high volumes of deliberate practice (Hollander, Meyers, & Leunes, 1995; Law, Côté, & Ericsson, 2007). For instance, young gymnasts who practice for over 16 hours a week have been shown to have higher incidences of back injuries (Goldstein, Berger, Windier, & Jackson, 1991). A sampling approach in child-controlled play (e.g. deliberate play) rather than highly adult-controlled practice (e.g. deliberate practice) has been proposed as a strategy to limit overuse and other sport-related injuries (Micheli, Glassman, & Klein, 2000). In summary, sampling may protect against sport attrition by limiting sport related injuries and allowing children to have early experiences in sport that are enjoyable. Psychosocial Benefits of Sampling Only a small percentage of children who participate in school sports ever become elite athletes. Therefore, the psychosocial outcomes of sport participation are particularly important to consider. Recent studies with youth between the ages of 11 to 17 have found that those who are involved in a variety of extracurricular activities (e.g. sports, volunteer, arts) score more favourably on outcome measures such as Grade Point Average (GPA; Fredricks & Eccles, 2006a) and positive peer relationships (Fredricks & Eccles, 2006b) than youth who participate in fewer activities. These patterns are thought to exist due to each extracurricular activity bringing its own distinct pattern of socialization experiences that reinforce certain behaviours and/or teach various skills (Fredricks & Eccles, 2006b; Rose-Krasnor, Bussen, Willoughby, & Chambers, 2006). This contention is corroborated by studies of children and youths' experiences in extracurricular activities indicating that youth have unique experiences in each activity that contribute to their development (Hansen, Larson, & Dworkin, 2003; Larson, Hansen, & Moneta, 2006). This has led Wilkes and Côté (2007) to propose that children who sample different activities (through their own choice or by virtue of parental direction), have a greater chance of developing the following five developmental outcomes compared to children who specialize in one activity: 1) life skills, 2) prosocial behaviour, 3) healthy identity, 4) diverse peer groups and 5) social capital.

Prescription drug samples: Does this marketing strategy counteract policies for quality use of medicines?

Prescription drug samples, as used by the pharmaceutical industry to market their products, are of current interest because of their influence on prescribing, and their potential impact on consumer safety. Very little research has been conducted into the use and misuse of prescription drug samples, and the influence of samples on health policies designed to improve the rational use of medicines. This is a topical issue in the prescription drug debate, with increasing costs and increasing concerns about optimizing use of medicines. This manuscript critically evaluates the research that has been conducted to date about prescription drug samples, discusses the issues raised in the context of traditional marketing theory, and suggests possible alternatives for the future.

Accuracy and optimal sampling in Monte Carlo solution of population balance equations

Implementation of a Monte Carlo simulation for the solution of population balance equations (PBEs) requires choice of initial sample number (N0), number of replicates (M), and number of bins for probability distribution reconstruction (n). It is found that Squared Hellinger Distance, H2, is a useful measurement of the accuracy of Monte Carlo (MC) simulation, and can be related directly to N0, M, and n. Asymptotic approximations of H2 are deduced and tested for both one-dimensional (1-D) and 2-D PBEs with coalescence. The central processing unit (CPU) cost, C, is found in a power-law relationship, C= aMNb0, with the CPU cost index, b, indicating the weighting of N0 in the total CPU cost. n must be chosen to balance accuracy and resolution. For fixed n, M × N0 determines the accuracy of MC prediction; if b > 1, then the optimal solution strategy uses multiple replications and small sample size. Conversely, if 0 < b < 1, one replicate and a large initial sample size is preferred. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2394–2402, 2015

The Benefits of Sampling Sports During Childhood

Sampling may promote prolonged engagement in sport by limiting physical injuries (Fraser-Thomas et al., 2005). Overtraining injuries are a concern for young athletes who specialize in one sport and engage in high volumes of deliberate practice (Hollander, Meyers, & Leunes, 1995; Law, Côté, & Ericsson, 2007). For instance, young gymnasts who practice for over 16 hours a week have been shown to have higher incidences of back injuries (Goldstein, Berger, Windier, & Jackson, 1991). A sampling approach in child-controlled play (e.g. deliberate play) rather than highly adult-controlled practice (e.g. deliberate practice) has been proposed as a strategy to limit overuse and other sport-related injuries (Micheli, Glassman, & Klein, 2000). In summary, sampling may protect against sport attrition by limiting sport related injuries and allowing children to have early experiences in sport that are enjoyable. Psychosocial Benefits of Sampling Only a small percentage of children who participate in school sports ever become elite athletes. Therefore, the psychosocial outcomes of sport participation are particularly important to consider. Recent studies with youth between the ages of 11 to 17 have found that those who are involved in a variety of extracurricular activities (e.g. sports, volunteer, arts) score more favourably on outcome measures such as Grade Point Average (GPA; Fredricks & Eccles, 2006a) and positive peer relationships (Fredricks & Eccles, 2006b) than youth who participate in fewer activities. These patterns are thought to exist due to each extracurricular activity bringing its own distinct pattern of socialization experiences that reinforce certain behaviours and/or teach various skills (Fredricks & Eccles, 2006b; Rose-Krasnor, Bussen, Willoughby, & Chambers, 2006). This contention is corroborated by studies of children and youths' experiences in extracurricular activities indicating that youth have unique experiences in each activity that contribute to their development (Hansen, Larson, & Dworkin, 2003; Larson, Hansen, & Moneta, 2006). This has led Wilkes and Côté (2007) to propose that children who sample different activities (through their own choice or by virtue of parental direction), have a greater chance of developing the following five developmental outcomes compared to children who specialize in one activity: 1) life skills, 2) prosocial behaviour, 3) healthy identity, 4) diverse peer groups and 5) social capital.

Ambient Water Monitoring Strategy for Iowa: 2016-2021, November 30, 2016

The Iowa Department of Natural Resources (DNR) Ambient Water Monitoring Program provides consistent, unbiased information about the condition of Iowa’s water resources to support decisions affecting the development, management and protection of these resources. To strengthen its services, the program worked with a variety of stakeholders and other DNR programs to develop a five-year strategy for Iowa’s ambient water monitoring efforts. The strategy identifies opportunities to improve the program’s effectiveness in several categories: monitoring objectives, sampling design, data management, products and services, and program evaluation and coordination. Iowa DNR managers and technical staff will use the new strategy to guide decisions affecting the ambient monitoring program over the next five years. The strategy should also serve as a robust informational resource for stakeholders, policy makers, legislators and the public.

Stream water‐quality monitoring conducted in support of the Iowa Nutrient Reduction Strategy (2016)

Monitoring of nitrogen and phosphorus in streams and rivers throughout Iowa is an essential element of the Iowa Nutrient Reduction Strategy (INRS). Sampling and analysis of surface water is necessary to develop periodic estimates of the amounts of nitrogen and phosphorus transported from Iowa. Surface and groundwater monitoring provides the scientific evidence needed to document the effectiveness of nutrient reduction practices and the impact they have on water quality. Lastly, monitoring data informs decisions about where and how best to implement nutrient reduction practices, by both point sources and nonpoint sources, to provide the greatest benefit at the least cost. The impetus for this report comes from the Water Resources Coordination Council (WRCC) which states in its 2014‐15 Annual Report “Efforts are underway to improve understanding of the multiple nutrient monitoring efforts that may be available and can be compared to the nutrient WQ monitoring framework to identify opportunities and potential data gaps to better coordinate and prioritize future nutrient monitoring efforts.” This report is the culmination of those efforts.

Cluster Analysis To Identify Elderly People's Profiles: A Healthcare Strategy Based On Frailty Characteristics.

The new social panorama resulting from aging of the Brazilian population is leading to significant transformations within healthcare. Through the cluster analysis strategy, it was sought to describe the specific care demands of the elderly population, using frailty components. Cross-sectional study based on reviewing medical records, conducted in the geriatric outpatient clinic, Hospital de Clínicas, Universidade Estadual de Campinas (Unicamp). Ninety-eight elderly users of this clinic were evaluated using cluster analysis and instruments for assessing their overall geriatric status and frailty characteristics. The variables that most strongly influenced the formation of clusters were age, functional capacities, cognitive capacity, presence of comorbidities and number of medications used. Three main groups of elderly people could be identified: one with good cognitive and functional performance but with high prevalence of comorbidities (mean age 77.9 years, cognitive impairment in 28.6% and mean of 7.4 comorbidities); a second with more advanced age, greater cognitive impairment and greater dependence (mean age 88.5 years old, cognitive impairment in 84.6% and mean of 7.1 comorbidities); and a third younger group with poor cognitive performance and greater number of comorbidities but functionally independent (mean age 78.5 years old, cognitive impairment in 89.6% and mean of 7.4 comorbidities). These data characterize the profile of this population and can be used as the basis for developing efficient strategies aimed at diminishing functional dependence, poor self-rated health and impaired quality of life.

Convergence Of A Specialized Root Trait In Plants From Nutrient-impoverished Soils: Phosphorus-acquisition Strategy In A Nonmycorrhizal Cactus.

In old, phosphorus (P)-impoverished habitats, root specializations such as cluster roots efficiently mobilize and acquire P by releasing large amounts of carboxylates in the rhizosphere. These specialized roots are rarely mycorrhizal. We investigated whether Discocactus placentiformis (Cactaceae), a common species in nutrient-poor campos rupestres over white sands, operates in the same way as other root specializations. Discocactus placentiformis showed no mycorrhizal colonization, but exhibited a sand-binding root specialization with rhizosheath formation. We first provide circumstantial evidence for carboxylate exudation in field material, based on its very high shoot manganese (Mn) concentrations, and then firm evidence, based on exudate analysis. We identified predominantly oxalic acid, but also malic, citric, lactic, succinic, fumaric, and malonic acids. When grown in nutrient solution with P concentrations ranging from 0 to 100 μM, we observed an increase in total carboxylate exudation with decreasing P supply, showing that P deficiency stimulated carboxylate release. Additionally, we tested P solubilization by citric, malic and oxalic acids, and found that they solubilized P from the strongly P-sorbing soil in its native habitat, when the acids were added in combination and in relatively low concentrations. We conclude that the sand-binding root specialization in this nonmycorrhizal cactus functions similar to that of cluster roots, which efficiently enhance P acquisition in other habitats with very low P availability.