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Abstract Background Indoor air pollution (IAP) from solid fuels is a serious health problem in low-income countries that can be alleviated using improved stoves. Although women are the principal users, few studies have investigated the self-assessed impact of the stoves on their health and lives. Methods This study was conducted in rural highland Guatemala, involving 89 intervention and 80 control Mayan Indian young women (mean 27.8 years, SD 7.2). Outcomes were assessed after approximately 18 months use of the new stove. Our objectives were to compare self-rated health and change in health among women participating in a randomised control trial comparing a chimney stove with an open fire, to describe impacts on women's daily lives and their perceptions of how reduced kitchen smoke affects their own and their children's health. Results On intention-to-treat analysis, 52.8% of intervention women reported improvement in health, compared to 23.8% of control women (p < 0.001). Among 84 intervention women who reported reduced kitchen smoke as an important change, 88% linked this to improvement in their own health, particularly for non-respiratory symptoms (for example eye discomfort, headache); 57% linked reduced smoke to improvement in their children's health, particularly sore eyes. Conclusion Women's perception of their health was improved, but although smoke reduction was valued, this was linked mainly with alleviation of non-respiratory symptoms like eye discomfort and headache. More focus on such symptoms may help in promoting demand for improved stoves and cleaner fuels, but education about more severe consequences of IAP exposure is also required.

Abstract Background Elderly population is on rise. It is an ethical dilemma how aggressive one should be when it comes to treat cancer in elderly. Presumed fear of increased postoperative morbidity and mortality has resulted in delivery of sub-optimal cancer surgery. Methods In this review article we visit physiology of the aged, tools available to assess surgical risks in oncogeriatric patients, and current practice in the management of common cancers encountered in surgical oncology, with the view of increasing awareness on optimising surgical management of senior patients with cancer. A pubmed search for cancer, surgery, elderly, was carried out. Results Cancer is on rise with increasing age predominantly affecting breast, gastrointestinal tract and lung. Increasingly more surgeons are offering surgery to elderly cancer patient but selection bias is prevalent. Available data reflect short and long-term outcome of cancer surgery in elderly is not greatly different to that of younger patient. Declining physiological reserve along with inability to respond adequately to physiological stress are salient age related changes. Comprehensive Geriatric Assessment (CGA) is not tested in surgical patient. There is need for a tool to define individualised operative risk. Preoperative assessment of cancer in elderly is designed to offer this information based on functional status of an individual utilising currently available tools of risk assessment. Conclusion All elderly cancer patients should be offered optimal treatment depending on their functional status not on chronological age. Oncogeriatric patient would benefit from dedicated multidisciplinary approach. Recruitment of elderly cancer patients to more clinical trials is needed to enhance our knowledge and to offer optimum treatment to this unique subgroup.

An overview of the state of the American diet, how it relates to public health outcomes and the obesity epidemic, and how it arises from the policy and infrastructure that have been developed over the course of the 20th and 21st centuries. The article concludes by laying out concrete solutions for urban revitalization, providing people in underserved communities sovereignty over their food supply, and work with multi-stakeholder cooperatives to overcome the effects of food insecurity and poor diet quality., (Copyright © 2023 Elsevier Inc. All rights reserved.)

E-cigarette use is prohibited in most smoke-free environments. The effect of this policy on tobacco consumption could be examined using the Experimental Tobacco Marketplace (ETM). The ETM allows observation of policy on smokers' purchasing behavior under conditions that simulate "real-world" circumstances. A within-subject design was used to evaluate the effect of workplace policy (Vaping Allowed vs. Not Allowed) and nicotine concentration (24 mg/mL vs. 0 mg/mL) on tobacco product consumption. Participants (n = 31) completed one sampling and two ETM/workplace sessions per week for 2 weeks. During the sampling session, participants were given an e-cigarette with a 2-day supply of a commercially available e-liquid of their preferred flavor. Before purchasing, participants were informed whether e-cigarette use was permitted. During the four ETM sessions, participants purchased for the following 24 hr, including the 4-hr work shift that started immediately after buying products in the ETM. The workplace session consisted of data entry tasks in a mock office environment. Participants could use any purchased tobacco products during two 15-min breaks. Condition order was counterbalanced. The results show that permitting E-cigarette use in the workplace increased e-liquid purchase on average, but nicotine concentration had no effect on e-liquid demand. Cigarette demand was unaltered across conditions. The present study suggests that allowing e-cigarette use in the workplace would increase demand for e-liquid regardless of nicotine strength. However, it would not change conventional cigarette demand. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Rationale: Delay discounting, in which an animal chooses between a small, immediate or large, delayed reinforcer, is an experimental model of impulsivity. In previous studies, d-amphetamine has both increased and decreased preference for larger-delayed reinforcers depending on experimental conditions., Objective: Identify genotype X environment interactions responsible for these disparate findings in a single study and assess the hypothesis that baseline-dependence unifies d-amphetamine's effects., Methods: Delay discounting by BALB/c and C57Bl/6 mice was evaluated using a choice procedure in which six delays to a larger reinforcer were presented in a single session. Components were presented both with and without stimuli that uniquely signaled reinforcer delays. d-Amphetamine's (0.1-1.7 mg/kg) effects on delay and magnitude sensitivity were assessed when specific stimuli did or did not uniquely signal the delay to a larger reinforcer. d-Amphetamine's effects were determined using a model-comparison approach., Results: During baseline, magnitude and delay sensitivity were identical across signal conditions for BALB/c mice and generally greater than the C57Bl/6 mice. For C57Bl/6 mice, magnitude and delay sensitivity were higher during the signaled than the unsignaled component. Amphetamine decreased delay sensitivity during both components for BALB/c mice, but this effect was attenuated by delay-specific stimuli. For C57Bl/6 mice, amphetamine decreased their high magnitude and delay sensitivity when delays were signaled and, conversely, increased the low magnitude and delay sensitivity when delays were unsignaled., Conclusions: BALB/c mice showed high delay and magnitude sensitivity regardless of signal conditions. C57Bl/6's magnitude and delay sensitivity depended on signaling. d-Amphetamine usually decreased high baseline delay- and magnitude sensitivity and increased low sensitivities, a baseline-dependence that occurred regardless of whether delay sensitivity was driven by biological (genotype) or environmental (signaling) variables. The C57Bl/6 mouse may be a good model of environmentally-induced impulsivity while BALB/c mice could model impulsivity with a strong genetic contribution., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: Research concerning trans-disease processes aims to ascertain an underlying mechanism of several seemingly dissonant behaviors, pathological conditions, or both. The theory of reinforcer pathology posits that excessive delay discounting and the maladaptive overvaluation of a particular commodity underlie a variety of dysfunctional health behavior ranging from substance abuse to overeating and financial responsibility. The present study extends recent health behavior research by examining the extent delay discounting and food valuation correlate with engagement in a latent factor model of health and financial behaviors among healthy-weight participants and participants with obesity using the Health Behaviors Questionnaire. Method: A total of 700 participants ( n = 340, body mass index [BMI] < 30; n = 360, BMI > 30 kg/m2) were recruited using Amazon Mechanical Turk. Participants completed a monetary delay discounting assessment, the Health Behaviors Questionnaire, and 2 measures of food valuation: Behavioral economic demand and the Power of Food Scale (PFS). Results: Utilizing structural equation modeling, both delay discounting and food valuation significantly correlated with engagement in health and financial behavior for both groups. The comparison of latent factors between groups indicated that participants with obesity were less likely to engage in multiple health behaviors and that these differences can be partially attributed to differences in delay discounting and food valuation. Conclusion: These results replicate previous research and further support the role of delay discounting as a trans-disease process. Given these results, trans-disease interventions, such as episodic future thinking, designed to specifically target reinforcer pathology may have a profound effect on overall functioning. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Introduction: The experimental tobacco marketplace (ETM) approximates real-world situations by estimating the effects of several, concurrently available products and policies on budgeted purchasing. Although the effects of increasing cigarette price on potentially less harmful substitutability are well documented, the effects of other, nuanced pricing policies remain speculative. This study used the ETM as a tool to assess the effects of two pricing policies, conventional cigarette taxation and e-liquid subsidization, on demand and substitutability., Methods: During sampling periods, participants were provided 2-day samples of 24 mg/mL e-liquid, after which ETM purchase sessions occurred. Across two ETM sessions, conventional cigarettes were taxed or e-liquid was subsidized in combination with increasing cigarette price. The other four available products were always price constant and not taxed or subsidized., Results: E-liquid functioned as a substitute for conventional cigarettes across all conditions. Increasing cigarette taxation and e-liquid subsidization increased the number of participants for which e-liquid functioned as a substitute. Cigarette taxation decreased cigarette demand, by decreasing demand intensity, and marginally increased the initial intensity of e-liquid substitution, but did not affect the functions' slopes (substitutability). E-liquid subsidization resulted in large increases in the initial intensity of e-liquid substitution, but did not affect e-liquid substitutability nor cigarette demand., Implications: 24 mg/mL e-cigarette e-liquid was the only product to significantly substitute for cigarettes in at least one condition throughout the experiment; it functioned as a significant substitute throughout all four tax and all four subsidy conditions. Increasing cigarette taxes decreased cigarette demand through decreases in demand intensity but did not affect e-cigarette substitution. Increasing e-liquid subsidies increased e-liquid initial intensity of substitution but did not affect cigarette demand., Conclusions: This study extended research on the behavioral economics of conventional cigarette demand and e-liquid substitutability in a complex marketplace. The results suggest that the most efficacious method to decrease conventional cigarette purchasing and increase e-liquid purchasing may involve greatly increasing cigarette taxes while also increasing the value of e-liquid through potentially less harmful product subsidization or differential taxation., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background and Aims: Government regulations of nicotine vaping products (NVP) have evolved rapidly during the past decade. The impact of NVP regulatory environment and vaping on cigarette demand is unknown. The current study aims to investigate whether or not respondents' reported cigarette demand, as measured by a hypothetical cigarette purchase task, varies with (1) smoking status, (2) vaping status or (3) NVP regulatory environment (country used as proxy)., Design: Cross-sectional survey data from wave 1 of the International Tobacco Control (ITC) Four Country Smoking and Vaping (4CV) Survey (2016)., Setting: Australia, Canada, England and the United States., Participants: A total of 10 316 adult smokers., Measurements: A hypothetical purchase task asked smokers to estimate how many cigarettes they would purchase for consumption in a single day across multiple cigarette prices. Responses were used to derive measures of cigarette demand. Overall sensitivity of cigarette consumption to price increases was quantified to index cigarette demand elasticity, whereas estimated consumption when cigarettes are free was used to index cigarette demand intensity., Findings: A majority of the non-daily smokers had previously smoked daily (72.3%); daily vapers were more likely to be former daily smokers (89.9%) compared to non-daily vapers (70.1%) and non-vapers (69.2%) (P < 0.001). The smoking status × vaping status interaction was significant for cigarette demand intensity (F = 4.93; P = 0.007) and elasticity (F = 7.30; P = 0.001): among non-daily smokers, vapers reported greater intensity but lower elasticity (i.e. greater demand) relative to non-vapers (Ps < 0.05). Among daily smokers, daily vapers reported greater intensity relative to non-vapers (P = 0.005), but vaping status did not impact elasticity (Ps > 0.38). Intensity was higher in Australia compared with all other countries (Ps < 0.001), but elasticity did not vary by country (F = 2.15; P = 0.09)., Conclusions: In a hypothetical purchase task, non-daily smokers showed lower price elasticity if they used e-cigarettes than if they did not, while there was no clear difference in elasticity between e-cigarette users and non-users among daily smokers or according to regulatory environment of their country with regard to e-cigarettes., (© 2018 Society for the Study of Addiction.)

Background: The Experimental Tobacco Marketplace (ETM) is a digital storefront in which participants can purchase tobacco products using an account balance that reflects their typical tobacco product purchasing. The ETM is also an ideal resource to investigate the harm-reduction potential of alternative nicotine products such as e-cigarettes. In a series of experiments, we explored the effects of harm-reduction narratives that encouraged e-cigarette substitution of conventional cigarettes in the ETM. These narratives incorporated different cognitive biases in order to determine which strategy is most effective., Methods: In both experiments, participants, recruited from Amazon Mechanical Turk, read a narrative about a friend that either falls ill or faces financial difficulties and then made purchases in the ETM. Some of these narratives specifically incorporated different cognitive biases including trusting authority. Across ETM trials, the price of conventional cigarettes increased while the price of the alternative products, including e-cigarettes, remained constant., Results: Across both experiments, a general pattern emerged supporting the effectiveness of narratives in increasing e-cigarette purchasing. Importantly, from a harm-reduction perspective, this increase in e-cigarette substitution frequently corresponded with a decrease in conventional cigarette purchasing., Conclusions: Narratives can decrease conventional cigarette and increase e-cigarette purchasing in an ETM that mimics real-world marketplaces. Invoking different cognitive biases may bolster this effect. Narratives can be a valuable harm-reduction tool because they are cost-effective, can be widely disseminated, and can be personalized to individuals., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Despite promising decreases in overall smoking rates, a significant proportion of the population continues to engage in this costly behavior. Substituting e-cigarettes for conventional cigarettes is an increasingly popular harm-reduction strategy. Narratives may be one method of increasing the substitutability of e-cigarettes. Participants (N = 160) were assigned to 1 of 4 narratives that described a close friend becoming ill. In the positive narrative, participants read about a friend that became ill but learned it was only the flu. In the negative narrative, the friend became ill from smoking cigarettes; in the negative regret narrative, the friend became ill from smoking cigarettes and explicitly expressed regret for having started smoking; and in the negative change narrative, the friend became ill from smoking, switched to e-cigarettes, and made a full recovery. Participants then completed an experimental tobacco marketplace (ETM) in which they could purchase conventional cigarettes and alternative nicotine products, including e-cigarettes. Across ETM trials, the price of conventional cigarettes increased while the price of the alternative products remained constant. Initial purchasing of conventional cigarettes decreased and initial purchasing of e-cigarettes increased in the negative-change group compared with the other three groups. This finding was moderated by conventional cigarette dependence and perception of e-cigarette risk but not previous e-cigarette exposure. Narratives can change conventional cigarette and e-cigarette purchasing in an ETM that mimics real-world marketplaces. Narratives can be a valuable harm-reduction tool because they are cost-effective, can be widely disseminated, and can be personalized to individuals. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Background: The experimental tobacco marketplace (ETM) provides a method to estimate, prior to implementation, the effects of new products or policies on purchasing across various products in a complex tobacco marketplace. We used the ETM to examine the relationship between nicotine strength and substitutability of alternative products for cigarettes to contribute to the literature on regulation of e-liquid nicotine strength., Methods: The present study contained four sampling and four ETM purchasing sessions. During sampling sessions, participants were provided 1 of 4 e-liquid strengths (randomised) to sample for 2 days followed by an ETM purchasing session. The nicotine strength sampled in the 2 days prior to an ETM session was the same strength available for purchase in the next ETM. Each participant sampled and could purchase 0 mg/mL, 6 mg/mL, 12 mg/mL and 24 mg/mL e-liquid, among other products, during the study., Results: Cigarette demand was unaltered across e-liquid strength. E-liquid was the only product to substitute for cigarettes across more than one e-liquid strength. Substitutability increased as a function of e-liquid strength, with the 24 mg/mL displaying the greatest substitutability of all products., Conclusions: The present study found that e-liquid substitutability increased with nicotine strength, at least up to 24 mg/mL e-liquid. However, the effects of e-liquid nicotine strength on cigarette purchasing were marginal and total nicotine purchased increased as e-liquid nicotine strength increased., Competing Interests: Competing interests: WKB is a principal in HealthSim, LLC, and NotifiUs, LLC., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2019. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Delay discounting, the devaluation of delayed reinforcers, is one defining behavioral economic characteristic of cigarette smokers. Attempts at abstinence by smokers that result in relapse are conceptualized in this framework as preference reversals. Despite preference reversals being predicted by delay discounting models, little research has investigated the association between discount rate and preference reversals. The present study extended this research by examining the relation between discounting and preference reversals. Because previous research indicates that cigarette smokers discount at higher rates than controls and that past and future discounting are symmetrical, the present study assessed the relation between these two processes when hypothetical money was distanced in the past and future, respectively. These assessments of delay discounting and preference reversals were adapted from Yi, Matusiewicz, and Tyson (2016) and examined in 68 smokers and 68 nonsmokers using the crowdsourcing program Amazon Mechanical Turk. Smokers discounted both past and future hypothetical money more steeply than demographically matched controls. Smokers switched preference from the smaller-sooner (SS) to the larger-later (LL) outcome more slowly than nonsmokers, consistent with smokers' steeper delay discounting. For each group, significant positive correlations between past and future discount rates and past and future preference reversals was obtained. The overall pattern of results illustrate symmetry between past and future discounting and preference reversals, respectively and that discount rate is positively associated with the timing of preference reversals. Importantly, the results confirm that cigarette smokers discount more and reverse preference from a SS to a LL reward later than controls. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The evolution of science derives, in part, from the development and use of new methods and techniques. Here, we discuss one development that may have impact on the understanding of tobacco regulatory science: namely, the application of behavioral economics to the complex tobacco marketplace. The purpose of this paper is to review studies that examine conditions impacting the degree to which electronic nicotine delivery system (ENDS) products substitute for conventional cigarettes in the Experimental Tobacco Marketplace (ETM). Collectively, the following factors constitute the current experimental understanding of conditions that will affect ENDS use and substitution for conventional cigarettes: increasing the base price of conventional cigarettes, increasing taxation of conventional cigarettes, subsidizing the price of ENDS products, increasing ENDS nicotine strength, and providing narratives that illustrate the potential health benefits of ENDS consumption in lieu of conventional cigarettes. Each of these factors are likely moderated by consumer characteristics, which include prior ENDS use, ENDS use risk perception, and gender. Overall, the ETM provides a unique method to explore and identify the conditions by which various nicotine products may interact with one another that mimics the real world. In addition, the ETM permits the efficacy of a broad range of potential nicotine policies and regulations to be measured prior to governmental implementation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Cigarette smokers show greater delay discounting (devaluation of delayed consequences) than non-smokers, suggesting that rapid devaluation of the future contributes to tobacco use through a mechanism in which tobacco-related health consequences are too delayed to discourage smoking. However, little work has quantified delay discounting in relation to electronic cigarette (EC) use, a tobacco product that many users believe to pose fewer negative health consequences than cigarettes., Methods: We assessed discounting of delayed monetary rewards in a web-based sample of 976 participants, stratified by both EC use (current and never) and cigarette use (current, former, and never)., Results: Controlling for demographic variance, current EC users generally showed greater discounting than never EC users (p = .019). Current cigarette smokers also showed greater discounting than former and never smokers (p < .001). However, the between-group difference for EC use was much smaller (η p 2  = .006) than for cigarette use (η p 2  = .026). Moreover, differences in discounting in relation to EC use were not statistically apparent in most pairwise comparisons. Most notably, the difference between former smokers who achieved smoking cessation by transitioning to ECs (i.e., exclusive EC users) and those who have never used ECs or cigarettes was nonsignificant and small (η p 2  = .010)., Conclusions: The smaller effect size for the association between delay discounting and current EC use, relative to current cigarette use, suggests that public perception of ECs as a safer alternative to cigarettes attenuates the role of delay discounting in decisions to use ECs., (Copyright © 2018. Published by Elsevier B.V.)

This review critically examines neurobehavioral theoretical developments in decision making in addiction in the 21st century. We specifically compare each theory reviewed to seven benchmarks of theoretical robustness, based on their ability to address: why some commodities are addictive; developmental trends in addiction; addiction-related anhedonia; self-defeating patterns of behavior in addiction; why addiction co-occurs with other unhealthy behaviors; and, finally, means for the repair of addiction. We have included only self-contained theories or hypotheses which have been developed or extended in the 21st century to address decision making in addiction. We thus review seven distinct theories of decision making in addiction: learning theories, incentive-sensitization theory, dopamine imbalance and systems models, opponent process theory, strength models of self-control failure, the competing neurobehavioral decision systems theory, and the triadic systems theory of addiction. Finally, we have directly compared the performance of each of these theories based on the aforementioned benchmarks, and highlighted key points at which several theories have coalesced., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Adolescence is marked by the continued development of the neural pathways that support choice and decision-making, particularly those involving dopamine signaling. Cocaine exposure during adolescence may interfere with this development and manifest as increased perseveration and delay discounting in adulthood, behavioral processes that are related to drug addiction. Adolescent mice were exposed to 30mg/kg/day of cocaine (n=11) or saline vehicle (n=10) for 14days and behavior was assessed in adulthood. In Experiment 1, performance on a spatial-discrimination-reversal procedure was evaluated. In the first two sessions following the first reversal, cocaine-exposed mice produced more preservative errors relative to controls. In Experiment 2, cocaine-exposed mice displayed steeper delay discounting than saline-exposed mice, effects that were reversed by acute cocaine administration. Experiment 3 examined responding maintained by a range of fixed-ratio schedules of reinforcement. An analysis based on a theoretical framework called Mathematical Principles of Reinforcement (MPR) was applied to response-rate functions of individual mice. According to MPR, differences in response-rate functions in adulthood were due to a steepening of the delay-of-reinforcement gradient, disrupted motoric capacity (lower maximum response rates), and enhanced reinforcer efficacy for the adolescent cocaine- compared with saline-exposed mice. Overall, these experiments suggest that chronic exposure to cocaine during adolescence may impair different features of 'executive functions' in adulthood, and these may be related to distortions in the impact of reinforcing events., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Adolescence is characterized by neural and behavior development that includes increases in novel experiences and impulsive choice. Experimental rodent models can characterize behavior phenotypes that typify adolescence. The present experiment was designed to characterize differences between adolescent (post-natal day (PND) 34-60) and adult (PND 70-96) BALB/c mice using a response-initiated spatial discrimination reversal (SDR) and incremental repeated acquisition of response chains (IRA) procedures. During SDR, adolescents omitted more trials and were slower to initiate trials than adults, but the age groups did not differ on accuracy and perseveration measures. During IRA, adolescents displayed poorer overall performance (measured by progress quotient), lower accuracy at individual chain links, and completed fewer long response chains (>3 links) than adults. In both procedures (SDR and IRA), the poorer performance of adolescents appeared to be related to the use of a response device that was spatially removed from reinforcer delivery. These results indicate that SDR and IRA performance can be established during the brief rodent adolescent period but that these two age groups' performances differ. We hypothesize that adolescent behavior is more sensitive than adult behavior to the spatiotemporal distance between response device and location of reinforcer delivery., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The importance of delay discounting to many socially important behavior problems has stimulated investigations of biological and environmental mechanisms responsible for variations in the form of the discount function. The extant experimental research, however, has yielded disparate results, raising important questions regarding Gene X Environment interactions. The present study determined the influence of stimuli that uniquely signal delays to reinforcement on delay discounting in two inbred mouse strains using a rapid-acquisition procedure. BALB/c and C57BL/6 mice responded under a six-component, concurrent-chained schedule in which the terminal-link delays preceding the larger-reinforcer were presented randomly across components of an individual session. Across conditions, components were presented either with or without delay-specific auditory stimuli, i.e., as multiple or mixed schedules. A generalized matching-based model was used to incorporate the impact of current and previous component reinforcer-delay ratios on current component response allocation. Sensitivity to reinforcer magnitude and delay were higher for BALB/c mice, but within-component preference reached final levels faster for C57Bl/6 mice. For BALB/c mice, acquisition of preference across blocks of a component was faster under the multiple than the mixed schedule, but final levels of sensitivity to reinforcement were unaffected by schedule. The speed of acquisition of preference was not different across schedules for C57Bl/6 mice, but sensitivity to reinforcement was higher under the multiple than the mixed schedule. Overall, differences in the acquisition and final form of the discount function were determined by a Gene X Environment interaction, but the presence of delay-specific stimuli attenuated genotype-dependent differences in magnitude and delay sensitivity., (© Society for the Experimental Analysis of Behavior.)

This paper discusses a method for overcoming the problem of weak sinks representing wells that result from spatial discretization effects when using MODPATH, the particle-tracking postprocessor for the ground water flow model MODFLOW. Weak sink cells are model cells that represent a well that does not discharge at a sufficiently large rate to capture all of the flow entering the cell; therefore, flowpaths within these cells cannot be uniquely defined because it is impossible to know whether a given water particle discharges to the well or passes through the cell. Creating a submodel of the well cell by using the nested rediscretization method can eliminate this ambiguity by converting the weak sink cell into a strong sink cell. The method is designed to be run manually for each well and for steady-state conditions. Other advantages, disadvantages, technical considerations, and limitations of the method are presented. Software created for the method consists of five Fortran programs that are operated using a set of instructions. A practical application of the method is presented by using an example wellhead-protection problem that demonstrates that nested rediscretization can provide more accurate particle-tracking results than those obtained by using a coarsely discretized model alone.

Any attempts at health care reform must take into account the needs of the patient, provider, and payer. Health care reform does not have to be a puzzle. The need to reduce medical costs must not be paramount to the equally important concerns of patient protection and provider fairness. The Georgia Comprehensive Protection Act will go a long way toward finding answers to the managed care puzzle.