Modeling VI and VDRL feedback functions: Searching normative rules through computational simulation.

We present the mathematical description of feedback functions of variable interval and variable differential reinforcement of low rates as functions of schedule size only. These results were obtained using an R script named Beak, which was built to simulate rates of behavior interacting with simple schedules of reinforcement. Using Beak, we have simulated data that allow an assessment of different reinforcement feedback functions. This was made with unparalleled precision, as simulations provide huge samples of data and, more importantly, simulated behavior is not changed by the reinforcement it produces. Therefore, we can vary response rates systematically. We've compared different reinforcement feedback functions for random interval schedules, using the following criteria: meaning, precision, parsimony, and generality. Our results indicate that the best feedback function for the random interval schedule was published by Baum (1981). We also propose that the model used by Killeen (1975) is a viable feedback function for the random differential reinforcement of low rates schedule. We argue that Beak paves the way for greater understanding of schedules of reinforcement, addressing still open questions about quantitative features of simple schedules. Also, Beak could guide future experiments that use schedules as theoretical and methodological tools.

Encouraging physical fitness in Brazilian adolescents with excess weight: can they outperform their eutrophic peers in some activities?

BACKGROUND: There is the need to encourage physical activity (PA) among adolescents with overweight or obesity. OBJECTIVES: The present study aimed to assess the relationship between health-related physical fitness (PF) and nutritional status, and to identify those activities more suited to adolescents with excess weight. METHODS: This cross-sectional study included 3,062 in-school adolescents, aged 10-18 years. We collected information on sex, age, weight, height, skinfold thickness, trunk height and leg length, and calculated body mass index (BMI) z-score, fat mass percentage, and peak height velocity (PHV). Participants were tested for PF by the 20-m shuttle run test (cardiorespiratory fitness); medicine ball throw and standing long jump tests (musculoskeletal fitness) and sit and reach test (flexibility). We used generalized linear mixed models (GLMM) to analyze the relationship between nutritional status and performance in the fitness tests, controlled for maturity offset and fat mass percentage. RESULTS: 1,563 (51%) were boys, mean age 12.6 years (±1.8), 22.8% were overweight and 12.5% had obesity. In both sexes, adolescents with obesity did better in the upper body strength test than their eutrophic peers. Boys with obesity had worse cardiorespiratory fitness and lower body muscular strength than eutrophic boys. Girls with obesity had similar cardiorespiratory fitness and better lower body strength than eutrophic girls. CONCLUSION: In muscular strength fitness tests, adolescents with obesity performed similarly to, or better than, their eutrophic peers. Motivation to maintain regular PA is reinforced by positive experiences. Interventions that emphasize muscular strength PF should be developed for adolescents with obesity.

Sensitivity and Specificity of Bedside Screening Tests for Detection of Aspiration in Patients Admitted to a Public Rehabilitation Hospital.

Early detection of dysphagia and specifically aspiration is essential to prevent and reduce complications of hospitalized patients in rehabilitation centers. Bedside screening test are often used to evaluate swallowing disorders, but their results may be questionable due to insufficient and inconsistent sensitivity and specificity. To compare the sensitivity and specificity of various bedside screening tests for detecting aspiration in hospitalized rehabilitation patients. A prospective observational study was performed in 150 consecutive patients of a tertiary rehabilitation hospital. Patients were evaluated regarding clinical predictors for aspiration, maximum phonation time (MPT), Eating Assessment Tool 10 (EAT-10) questionnaire, tongue strength and endurance (Iowa Oral Performance Instrument [IOPI]) and a swallowing test (Volume-Viscosity Swallow Test [V-VST]). Flexible Endoscopic Evaluation of Swallowing (FEES) was the reference test. Of the 144 patients included, 22% aspirated on FEES. Previous history of pneumonia, dysarthria, wet voice, and abnormal cough reflex were significantly associated with aspiration. The sensitivity, specificity and accuracy for V-VST (83.3%, 72.6%, 74.8%, respectively) and EAT-10 (82.8%, 57.7%, 62.8%, respectively) to detect aspiration were superior than those of other methods. Maximum tongue strength on IOPI and MPT presented high sensitivity but low specificity to detect aspiration. Clinical predictors of aspiration (previous history of pneumonia, dysarthria, wet voice, and abnormal cough reflex) associated with either V-VST or EAT-10 may be good screening methods to detect aspiration in patients hospitalized in a rehabilitation center.

The Edmonton Obesity Staging System: assessing a potential tool to improve the management of obesity surgery in the Brazilian public health services.

BACKGROUND: Limited access to publicly funded, insurance-covered, and self-paid obesity surgery is a reality worldwide. Waiting lists for procedures are usually based on chronologic criteria and body mass index (BMI)-defined obesity categorization. Obesity classification systems assess overall health and have been proposed as an alternative. OBJECTIVE: To investigate the correlation between BMI-based classification and the Edmonton Obesity Staging System (EOSS) to support current evidence that the assessment of the clinical severity of obesity could be a helpful tool to maximize access to surgery. SETTING: University hospital, Brazil. METHODS: Retrospective analysis of all 2011 to 2014 adult patients who underwent obesity surgery under the public health system. Data on sex, age, presurgical BMI, and co-morbidities were extracted from hospital records. Spearman correlation coefficients were used to assess the strength and direction of the relationship between BMI classification and EOSS. RESULTS: Of 565 patients, 79% were female, mean age 44.1 ± 10.9 years and mean BMI 46.9 ± 6.2 kg/m2. The most common EOSS stage was 2 (86.5%), followed by stages 3 (8.5%) and 1 (4.9%). There was no correlation between the severity of obesity measured by BMI and EOSS (ρ = -.030, P = .475). Older patients had higher Edmonton scores (ρ = .308, P < .001). No difference was observed regarding sex. CONCLUSIONS: No correlation was found between EOSS and BMI and between these and sex. Age correlated with both obesity indicators. EOSS was reproducible in Brazilian surgical patients and may be an important tool from a health services perspective contributing to the more efficient use of limited resources for obesity surgery.