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Background & Aims: Obesity has been associated with gastroesophageal reflux disease (GERD) and its complication, but the mechanism is unclear. We evaluated the association between obesity and function of lower esophageal sphincter (LOS) in subjects without GERD. Methods: We prospectively recruited consecutive obese (BMI >30) patients referred for weight reduction procedure and age- and sex-matched overweight (BMI 25–30) and normal weight (BMI ≥20 and <25) subjects. Exclusion criteria included esophagitis, reflux symptoms, use of proton pump inhibitor, hiatus hernia >2 cm, and diabetes mellitus with microvascular complication. All participants underwent combined 2-hour postprandial esophageal manometry and pH monitoring after a standard test meal followed by 24-hour ambulatory pH monitoring. Results: Eighty-four subjects (obese, 28; overweight, 28; normal weight, 28) were studied. All 3 groups had comparable mean LOS pressure, LOS length, and peristaltic function. During the postprandial period, both obese and overweight groups had substantial increase in 2-hour rate of transient lower esophageal sphincter relaxation (TLOSR) (normal weight: 2.1 ± 1.2 vs overweight: 3.8 ± 1.6 vs obese: 7.3 ± 2.0, P < .001), proportion of TLOSR with acid reflux (normal weight: 17.6% ± 22.0% vs overweight 51.8% ± 22.5% vs obese: 63.5% ± 21.7%, P < .001), and gastroesophageal pressure gradient (GOPG) (normal weight: 4.5 ± 1.2 mm Hg vs overweight: 7.1 ± 1.4 mm Hg vs obese: 10.0 ± 1.5 mm Hg, P < .001). Using multiple regression model, BMI (r 2: 0.70, B: 0.28, 95% CI: 0.24–0.33, P < .001) and waist circumference (r 2: 0.65, unstandardized regression coefficient [B]: 0.10, 95% CI: 0.08–0.11, P < .001) were significantly correlated with TLOSR. Conclusions: Obesity is associated with increased TLOSR and acid reflux during the postprandial period in subjects without GERD. Abnormal postprandial LOS function may be an early event in the pathogenesis of obesity-related GERD. [Copyright &y& Elsevier]

The complexity of human''s cooperative behavior cannot be fully explained by theories of kin selection and group selection. If reciprocal altruism is to provide an explanation for altruistic behavior, it would have to depart from direct reciprocity, which requires dyads of individuals to interact repeatedly. For indirect reciprocity to rationalize cooperation among genetically unrelated or even culturally dissimilar individuals, information about the reputation of individuals must be assessed and propagated in a population. Here, we propose a new framework for the evolution of indirect reciprocity by social information: information selectively retrieved from and propagated through dynamically evolving networks of friends and acquaintances. We show that for indirect reciprocity to be evolutionarily stable, the differential probability of trusting and helping a reputable individual over a disreputable individual, at a point in time, must exceed the cost-to-benefit ratio of the altruistic act. In other words, the benefit received by the trustworthy must out-weigh the cost of helping the untrustworthy. [Copyright &y& Elsevier]

The topology and the capacity of a traditional multilayer neural system, as measured by the number of connections in the network, has surprisingly little impact on its generalization ability. This paper presents a new adaptive modular network that offers superior generalization capability. The new network provides significant fault tolerance, quick adaption to novel inputs, and high recognition accuracy. We demonstrate this paradigm on recognition of unconstrained handwritten characters. [ABSTRACT FROM AUTHOR]