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.     

Geometric orientation by humans: angles weigh in

Human participants were trained to navigate to two geometrically equivalent corners of a parallelogram-shaped virtual environment. The unique shape of the environment combined three distinct types of geometric information that could be used in combination or in isolation to orient and locate the goals: the angular amplitudes of the corners, the relative wall length relationships, and the principal axis of symmetry. In testing, participants were placed in manipulated versions of the training environment that tested which types of geometry they had encoded and how angular information weighed in against the other two geometric properties. The test environments were (a) a rectangular environment that removed the angular information, (b) a rhombic environment that removed wall length information and drastically reduced the principal axis, and (c) a reverse-parallelogram-shaped environment that placed angular information against both wall length and principal axis information. Participants chose accurately in the rectangular and rhombus environments, despite the removal of one of the cues. In the conflict test, participants preferred corners with the correct angular amplitudes over corners that were correct according to both wall length relationships and the principal axis. These results are comparable to recent findings with pigeons and suggest that angles are a salient orientation cue for humans.     

Influence of perceived social support and functioning on the quality of life of patients with schizophrenia and their caregivers

Perception of social support and functioning of patients with schizophrenia and their primary caregivers and its relationship to quality of life are described. Forty-five patients and their 45 relatives, treated at the Mental Health Services in Arica, Chile, participated. Both patients and caregivers in the study have a poor perception of social support with regard to extra-family people, as well as a low social integration. However, patients showed adequate capacity to function within their immediate family. Unlike what was found in developed countries, these patients showed moderate levels of quality of life, with a strong relationship with perceptions of the social support they receive from family and significant others and the ability to establish and maintain social contacts. Quality of life of primary caregivers is linked to patients' ability to establish and maintain social contacts within the family group, as in other social instances, such as keeping a job. The results of the study suggest the need to consider the design and application of programs of support for these patients and their caregivers, with the central aim of the social functioning of the above-mentioned patients and their familiar and community integration.     

Predictors of quality of life enjoyment and satisfaction in individuals living with HIV and AIDS in a resource-constrained setting in South Africa

The burden of HIV disease is concentrated in sub-Saharan Africa, particularly in South Africa (SA). Whilst there have been many studies conducted on the biomedical and socio-psychological aspects of HIV and AIDS, insufficient attention has been paid to the quality of life of those infected with the virus. The primary purpose of the study was to determine the predictors of quality of life enjoyment and satisfaction (Q-LES) among individuals infected with HIV. A battery of questionnaires, which included the Hospital Anxiety and Depression Scale (HADS) and the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q), were administered to 121 participants. Data was analysed using SPSS. Of the total sample (n = 121), 74% were females. The study found that a large proportion (49.5%) of the sample within the age group 25–49 years old experienced psychological distress. Those who were not on antiretroviral treatment (ART) were significantly affected (66%). Psychological distress was significantly prevalent among HIV positive individuals and also the strongest predictor of Q-LES among these individuals.     

Facial attractiveness impressions precede trustworthiness inferences: lower detection thresholds and faster decision latencies

Prior research has found a relationship between perceived facial attractiveness and perceived personal trustworthiness. We examined the time course of attractiveness relative to trustworthiness evaluation of emotional and neutral faces. This served to explore whether attractiveness might be used as an easily accessible cue and a quick shortcut for judging trustworthiness. Detection thresholds and judgment latencies as a function of expressive intensity were measured. Significant correlations between attractiveness and trustworthiness consistently held for six emotional expressions at four intensities, and neutral faces. Importantly, perceived attractiveness preceded perceived trustworthiness, with lower detection thresholds and shorter decision latencies. This reveals a time course advantage for attractiveness, and suggests that earlier attractiveness impressions could bias trustworthiness inferences. A heuristic cognitive mechanism is hypothesised to ease processing demands by relying on simple and observable clues (attractiveness) as a substitute for more complex and not easily accessible information (trustworthiness).     

The use of virtual reality in the study, assessment, and treatment of body image in eating disorders and nonclinical samples: a review of the literature

This article reviews research into the use of virtual reality in the study, assessment, and treatment of body image disturbances in eating disorders and nonclinical samples. During the last decade, virtual reality has emerged as a technology that is especially suitable not only for the assessment of body image disturbances but also for its treatment. Indeed, several virtual environment-based software systems have been developed for this purpose. Furthermore, virtual reality seems to be a good alternative to guided imagery and in vivo exposure, and is therefore very useful for studies that require exposure to life-like situations but which are difficult to conduct in the real world. Nevertheless, review highlights the lack of published controlled studies and the presence of methodological drawbacks that should be considered in future studies. This article also discusses the implications of the results obtained and proposes directions for future research.     

Some Thoughts on A. H. Louie’s “More Than Life Itself: A Reflection on Formal Systems and Biology”

We review and discuss A. H. Louie’s book “More than Life Itself: A Reflexion on Formal Systems and Biology” from an interdisciplinary viewpoint, involving both biology and mathematics, taking into account new developments and related theories.     

Application of Hellison's Teaching Personal and Social Responsibility Model in physical education to improve self-efficacy for adolescents at risk of dropping-out of school

This study evaluated improvement in self-efficacy and personal and social responsibility among at-risk of dropping-out of school adolescents participating in a program in which Hellison's Teaching Personal and Social Responsibility Model was applied in physical education classes during the course of an academic year. Thirty at-risk adolescents aged 13-14 years old (23 boys, 7 girls) were assigned to an intervention group (12 boys and 3 girls) or a comparison group (11 boys, 4 girls), the latter of which did not participate in the program. Quantitative results showed a significant improvement in the students' self-efficacy for enlisting social resources and in self-efficacy for self-regulated learning. Qualitative results showed an improvement in responsibility behaviors of participants in the intervention group. This suggests that the model could be effective for improving psychological and social development in at-risk adolescents, and that physical education classes may be an appropriate arena for working with these young people.     

Absence of effect of the change of food context in the activity-based anorexia phenomenon in rats

The goal of this study was to analyse how the context in which animals remain during the period of access to food modulates the development of activity-based anorexia in rats. For this purpose, the effect of changing the context of the activity period and the eating period was measured in terms of body weight loss, reduction in food intake and increase in physical activity. A 2 yen 2 factorial design was implemented, by having or not having access to a running wheel, and by being exposed or not exposed to a context change. Results showed that exposure to different contexts for the wheel and for the food did not affect weight loss, food intake or activity levels. These results are in line with the theoretical position of Epling and Pierce (1992) that activity is induced by the food restriction regime.     

The Reverse-Caricature Effect Revisited: Familiarization With Frontal Facial Caricatures Improves Veridical Face Recognition

Prior research suggests that recognition of a person's face can be facilitated by exaggerating the distinctive features of the face during training. We tested if this 'reverse-caricature effect' would be robust to procedural variations that created more difficult learning environments. Specifically, we examined whether the effect would emerge with frontal rather than three-quarter views, after very brief exposure to caricatures during the learning phase and after modest rotations of faces during the recognition phase. Results indicate that, even under these difficult training conditions, people are more accurate at recognizing unaltered faces if they are first familiarized with caricatures of the faces, rather than with the unaltered faces. These findings support the development of new training methods to improve face recognition.