Satisfiability Testing for Boolean Formulas Using Δ-trees

The tree-based data structure of -tree for propositional formulas is introduced in an improved and optimised form. The -trees allow a compact representation for negation normal forms as well as for a number of reduction strategies in order to consider only those occurrences of literals which are relevant for the satisfiability of the input formula. These reduction strategies are divided into two subsets (meaning- and satisfiability-preserving transformations) and can be used to decrease the size of a negation normal form A at (at most) quadratic cost. The reduction strategies are aimed at decreasing the number of required branchings and, therefore, these strategies allow to limit the size of the search space for the SAT problem.     

Psychosocial Treatment Strategies in the MTA Study: Rationale, Methods, and Critical Issues in Design and Implementation

The Collaborative Multimodal Treatment Study of Children with Attention Deficit Hyperactivity Disorder (ADHD), the MTA, is the first multisite, cooperative agreement treatment study of children, and the largest psychiatric/psychological treatment trial ever conducted by the National Institute of Mental Health. It examines the effectiveness of Medication vs. Psychosocial treatment vs. their combination for treatment of ADHD and compares these experimental arms to each other and to routine community care. In a parallel group design, 579 (male and female) ADHD children, aged 7–9 years, 11 months, were randomly assigned to one of the four experimental arms, and then received 14 months of prescribed treatment (or community care) with periodic reassessments. After delineating the theoretical and empirical rationales for Psychosocial treatment of ADHD, we describe the MTA's Psychosocial Treatment strategy applied to all children in two of the four experimental arms (Psychosocial treatment alone; Combined treatment). Psychosocial treatment consisted of three major components: a Parent Training component, a two-part School Intervention component, and a child treatment component anchored in an intensive Summer Treatment Program. Components were selected based on evidence of treatment efficacy and because they address comprehensive symptom targets, settings, comorbidities, and functional domains. We delineate key conceptual and logistical issues faced by clinical researchers in design and implementation of Psychosocial research with examples of how these issues were addressed in the MTA study.Deceased     

Comparative analysis of different correction methods for measuring Rod-and-Frame Test performance

A comparative analysis was conducted of five different methods for scoring the Rod-and-Frame Test to examine the convergent validities of each of the five methods with performance on the Embedded Figures Test for a sample of 408 13- to 16-yr.-olds. The scoring methods included the absolute error, the algebraic error, the absolute value of the algebraic error, the frame effect, and an assessment of relative field dependence. Correlations obtained among the five methods and the Embedded Figures Test indicated different patterns for boys and girls. In general, the method which employed the absolute value of the algebraic error yielded the strongest convergent validity coefficients with scores on the Embedded Figures Test and Group Embedded Figures Test for boys (.62 and -.54, respectively), although, for girls, the absolute algebraic error and absolute error both yielded coefficients of .50 with Embedded Figures Test scores and -.46 with Group Embedded Figures Test scores.     

The development of the Cultural Health Attributions Questionnaire (CHAQ)

Current general health belief measures that are used to assess health behaviors do not capture the full range of health beliefs present among Latinos. The purpose of this study was to develop a reliable and valid measure of Latino health beliefs, the Cultural Health Attributions Questionnaire (CHAQ). Three hundred forty participants were recruited in 2 metropolitan areas with large Latino populations. Exploratory factor analysis revealed 2 highly interpretable 12-item subscales: the Equity Attribution and the Behavioral-Environmental Attribution scales. Examination of the relationships between the subscales and measures of acculturation provided evidence of construct validity. Moreover, the prediction of health care behavior by the CHAQ also indicated initial criterion validity.     

Family functioning and early onset of sexual intercourse in Latino adolescents

The purpose of this study was to identify factors associated with early onset of sexual intercourse. Within an ecological system's conceptual framework, familial factors associated with early onset of sexual activity were identified in a sample of 425 adolescents from San Juan metro area schools. Measures included questions about sexual activity, sexual permissiveness, and such familial variables as: discipline, parental supervision, and parental support. Significant relationships were observed between early onset of sexual intercourse and parental supervision, discipline, parental support, and parents' marital status. Results suggest the key role of parents and family in prevention of HIV-risk behaviors among adolescents in terms of delaying sexual onset. Overall, the study described youths who postponed sexual activity as having greater support, supervision, and parental involvement.     

Representation and working memory in early arithmetic

Working memory has been implicated in the early acquisition of arithmetic skill, but the relations among different components of working memory, performance on different types of arithmetic problems, and development have not been explored. Preschool and Grade 1 children completed measures of phonological, visual-spatial, and central executive working memory, as well as nonverbal and verbal arithmetic problems, some of which included irrelevant information. For preschool children, accuracy was higher on nonverbal problems than on verbal problems, and the best and only unique predictor of performance on the standard nonverbal problems was visual-spatial working memory. This finding is consistent with the view that most preschoolers use a mental model for arithmetic that requires visual-spatial working memory. For Grade 1 children, performance was equivalent on nonverbal and verbal problems, and phonological working memory was the best predictor of performance on standard verbal problems. For both age groups, problems with added irrelevant information were substantially more difficult than standard problems, and in some cases measures of the central executive predicted performance. Assessing performance on different components of working memory in conjunction with different types of arithmetic problems provided new insights into the developing relations between working memory and how children do arithmetic.