SAT-Solving in Practice, with a Tutorial Example from Supervisory Control

Satisfiability solving, the problem of deciding whether the variables of a propositional formula can be assigned in such a way that the formula evaluates to true, is one of the classic problems in computer science. It is of theoretical interest because it is the canonical NP-complete problem. It is of practical interest because modern SAT-solvers can be used to solve many important and practical problems. In this tutorial paper, we show briefly how such SAT-solvers are implemented, and point to some typical applications of them. Our aim is to provide sufficient information (much of it through the reference list) to kick-start researchers from new fields wishing to apply SAT-solvers to their problems. Supervisory control theory originated within the control community and is a framework for reasoning about a plant to be controlled and a specification that the closed-loop system must fulfil. This paper aims to bridge the gap between the computer science community and the control community by illustrating how SAT-based techniques can be used to solve some supervisory control related problems.     

Using implementation intentions to increase attendance for cervical cancer screening.

This article evaluates an intervention based on P. A Gollwitzer's (1993) concept of implementation intentions. Women registered at a medical practice in rural England (N?=?114) completed measures of the theory of planned behavior variables before a manipulation that induced one half of the sample to form implementation intentions specifying when, where, and how they would make the appointment. Subsequent attendance was determined from medical records. Findings show that the theory of planned behavior variables and previous delay behavior provided good prediction of attendance. However, despite equivalent motivation to attend, participants who formed implementation intentions were much more likely to attend for screening compared with controls (92% vs. 69%). Evidence also suggests that implementation intentions attenuated the relationship between previous delay behavior and subsequent attendance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social-cognitive determinants of hoist usage among health care workers.

Injuries caused by unsafe manual handling of patients are a major source of ill health in health care workers. The present study evaluated the ability of 4 classes of variable to predict use of a hoist when moving a heavily dependent patient. Variables examined were occupational role characteristics, such as hours of work and type of shift worked; biographics, including age and height; aspects of occupational context, such as number of hoists available and number of patients; and motivational variables specified by the theory of planned behavior (Ajzen, 1985) and protection motivation theory (Rogers, 1983). Regression analyses showed that background and social-cognitive variables were able to account for 59% of variance in intention to use a hoist and 41% of variance in use of the hoist assessed 6 weeks later. Height, hoist availability, coworker injunctive norm, perceived behavioral control, response cost, response benefits, and social and physical costs of not using the hoist each explained independent variance in motivation to use a hoist at work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Screening for principal versus comorbid conditions in psychiatric outpatients with the Psychiatric Diagnostic Screening Questionnaire.

In examining the performance of screening scales, a distinction should be made between principal and additional diagnoses. The Psychiatric Diagnostic Screening Questionnaire (PDSQ) is a brief, psychometrically strong self-report scale designed to screen for the most common Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) Axis I disorders encountered in outpatient mental health settings. In the present report, the authors compared the performance of the PDSQ in identifying principal and comorbid disorders. Seven hundred ninety-nine psychiatric outpatients completed the PDSQ and were interviewed with the Structured Clinical Interview for DSM-IV. The sensitivity and negative predictive values of the PDSQ subscales were similar for principal and additional diagnoses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stages of Change or Changes of Stage? Predicting Transitions in Transtheoretical Model Stages in Relation to Healthy Food Choice.

Relatively little research has examined factors that account for transitions between transtheoretical model (TTM) stages of change. The present study (N=787) used sociodemographic, TTM, and theory of planned behavior (TPB) variables, as well as theory-driven interventions to predict changes in stage. Longitudinal analyses revealed that sociodemographic, TPB, and 1 of the interventions predicted transitions between most stages of change. In fact, only progression from the preparation stage was not predictable. However, given that this change of stage marks the transition between cognition and actual behavior, the identification of variables that bridge this gap is crucial for the development of interventions to promote stage transitions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using the question-behavior effect to promote disease prevention behaviors: Two randomized controlled trials.

Objective: To test the efficacy of interventions based on the question-behavior effect in promoting the adoption of disease prevention behaviors. Design: In Study 1, adults from the general public were randomly allocated to complete a questionnaire about health checks (question-behavior effect condition) or not (control) and later received an invitation to attend for screening. In Study 2, health care professionals were randomly allocated to complete a questionnaire about influenza vaccination or not and later had the opportunity to receive a vaccination. Main Outcome Measures: We objectively assessed health check attendance (Study 1) and influenza vaccination (Study 2). Results: In Study 1, intention-to-treat analyses indicated that health check attendance was significantly higher in the question-behavior effect condition (68.3%) compared with the control condition (53.5%). In Study 2, intention-to-treat analyses indicated that influenza vaccination was significantly higher among participants in the question-behavior effect condition (42.0%) compared with the control condition (36.3%), and this effect persisted after controlling for demographic variables. Explanatory analyses indicated that the effects in both studies were attributable to completing rather than merely receiving the questionnaire and were stronger for those with positive attitudes or intentions about the target behavior. Conclusion: The question-behavior effect represents a simple, cost-effective means to increase disease prevention behaviors among the general public and health professionals. Implications for promoting health behaviors are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Psychosocial correlates of heterosexual condom use: a meta-analysis

Despite increasing incidence of HIV/AIDS, there has been no systematic review of correlates of condom use among heterosexual samples. To rectify this, the present study used meta-analysis to quantify the relationship between psychosocial variables and self-reported condom use. Six hundred sixty correlations distributed across 44 variables were derived from 121 empirical studies. Variables were organized in terms of the labeling, commitment, and enactment stages of the AIDS Risk Reduction Model (Catania, Kegeles, & Coates, 1990). Findings showed that demographic, personality, and labeling stage variables had small average correlations with condom use. Commitment and enactment stage variables fared better, with attitudes toward condoms, behavioral intentions, and communication about condoms being the most important predictors. Overall, findings support a social psychological model of condom use highlighting the importance of behavior-specific cognitions, social interaction, and preparatory behaviors rather than knowledge and beliefs about the threat of infection.     

Which survey questions change behavior? Randomized controlled trial of mere measurement interventions.

Objective: Evidence indicates that receiving a questionnaire about a behavior increases the likelihood that the person will perform that behavior—a phenomenon termed the mere measurement effect. This research tested the role of (a) the type of questions, and (b) questionnaire completion in optimizing the impact of mere measurement interventions designed to retain novice blood donors. Design: Novice blood donors (N = 4391) were randomly allocated to four conditions that varied the content of a questionnaire about blood donation (behavioral intention-only, behavioral intention plus regret, implementation intention-only, implementation intention plus regret) or to a no-questionnaire control condition. Main Outcome Measures: Objective measures of registration at blood drives were obtained at 6 and 12 months postbaseline. Results: Participants in the implementation intention-only condition donated more frequently at 6 months compared to participants in each of the other conditions. At 12 months both implementation intention conditions outperformed the other conditions. Implementation intentions increased the frequency of donations over 1 year by 12%. Measuring anticipated regret did not augment the impact of interventions whereas questionnaire completion had an important impact on donation behavior. Conclusion: Questions about implementation intentions but not behavioral intentions promote retention of novice blood donors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tellurium distribution in copper anode slimes smelting

Tellurium is a common minor constituent of copper anode slimes. The distribution of tellurium between the phases during slimes smelting is an important consideration, both in terms of metal quality and the capture of the oxidized tellurium. In this work, the oxidation by oxygen at 1100 °C of a silver-copper selenide matte containing 2 pct tellurium has been examined. The distribution of tellurium between the phases was determined as the extent of oxidation increased, and the system was modeled using a computational thermodynamics package. Oxidized tellurium was found to report to the slag, with none being removed with the gas. The thermodynamic model predicted, to an acceptable level, the tellurium content of all phases as oxidation progressed. It was used to show that oxidation by air rather than oxygen results in higher residual tellurium levels in silver metal and that the lower the smelting temperature, the greater the extent of tellurium elimination from silver to the slag.