Stress exposure and stress generation in child and adolescent depression: A latent trait-state-error approach to longitudinal analyses.

In 2 longitudinal studies of negative life events and depressive symptoms in adolescents (N = 708) and in children (N = 508), latent trait-state-error structural equation models tested both the stress generation hypothesis and the stress exposure hypothesis. Results strongly suggested that self-reports of depressive symptoms reflect the influence of a perfectly stable trait factor as well as a less stable state factor. Support emerged for both the stress generation model and the stress exposure model. When the state depression factor was modeled as predicting stress, support for the stress generation model appeared to increase with age. When the trait depression factor was modeled as the predictor of stress, support for the stress generation model did not vary with the child's age. In both models, support for the stress exposure remained relatively constant across age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding smoking cessation: The role of smokers' quit history.

Many studies have found smokers' quit history to correlate with quitting smoking, but little is known about the psychological processes explaining this relationship. This study uses the integrative model of behavioral prediction to examine how quit history affects quit intention. Data from 3,428 Dutch smokers demonstrate that quit history affects (a) beliefs about quitting and (b) the degree to which self-efficacy predicts quit intention. It seems that a relatively unsuccessful history of prior quit attempts reduces self-efficacy over quitting and strengthens the relationship of self-efficacy with the intention to quit. The results are used to call for more process-oriented research in order to advance our understanding of the relationship between quit history and quit intention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does solitary substance use increase adolescents' risk for poor psychosocial and behavioral outcomes? A 9-year longitudinal study comparing solitary and social users.

This longitudinal study compared Grade 8 solitary cigarette smokers (n = 541), drinkers (n = 577), and marijuana users (n = 148) with adolescents who restricted their use of these substances to social settings (ns = 562, 1,426, and 388, respectively) on adolescent functioning and young adult outcomes. In Grade 8, solitary users held more positive beliefs about the consequences of substance use, earned poorer grades, engaged in more deviant behavior, and devoted less time to school and more time to social activities. By age 23, these solitary users had lower educational attainment, poorer self-rated health, and greater substance use problems. Results indicate the importance of better understanding and addressing the needs of this understudied group of high-risk youth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Knowledge building in mathematics: Supporting collaborative learning in pattern problems

While it has been suggested that patterning activities support early algebra learning, it is widely acknowledged that the shift from perceiving patterns to understanding algebraic functions—and correspondingly, from reporting empirical patterns to providing explanations—is difficult. This paper reports on the collaborations of grade 4 students (n = 68) from three classrooms in diverse urban settings, connected through a knowledge-building environment (Knowledge Forum), when solving mathematical generalizing problems as part of an early algebra research project. The purpose of this study was to investigate the underlying principles of idea improvement and epistemic agency and the potential of knowledge building—as supported by Knowledge Forum—to support student work. Our analyses of student-generated collaborative workspaces revealed that students were able to find multiple rules for challenging problems and revise their own conjectures regarding those rules. Furthermore, the discourse was sustained over 8 weeks and students were able to find similarities across problem types without the support of teachers or researchers, suggesting that these grade-4 students had developed a disposition for evidence use and justification that eludes much older students.     

Polymer‐based transistors used as pixel switches in active‐matrix displays

A 2‐in. active‐matrix display was demonstrated, containing 4096 solution‐processed polymer‐based transistors. By using the polymer‐dispersed liquid‐crystal display (LCD) effect, this results in a reflective, low‐power display with paper‐like contrast. The influence of the transistor parameters on the display performance is analyzed by use of a model for charging and discharging of the pixel capacitors. Good agreement was obtained between the model and the experimental data. Scaling behavior allows estimation of the performance required for transistors in a quarter‐VGA display. These requirements are met by solution‐processed pentacene transistors.     

Sustainable Development and the Sustainability of Competitive Advantage: A Dynamic and Sustainable View of the Firm

Does the need for sustainable development hinder businesses’ ability to create value? Is a firm’s competitiveness negatively affected by considering that need? After quickly reviewing the main literature contributions on the relationship between business and society, and drawing from resource‐based view of the firm and sustainable development literature, this paper presents a proposal for a dynamic and sustainable view of the firm. It shows how considering the changes introduced into the competitive landscape by sustainable development influences the way in which companies develop their resources, capabilities and activities, fostering the persistence of competitive advantages based on knowledge and innovation.     

Exponential Stability of Slowly Time-Varying Nonlinear Systems

Let be a time-varying vector field depending on t containing a regular and a slow time scale (α large). Assume there exist a k (τ)≥1 and a γ(τ) such that ∥x _τ(t, t ₀, x ₀)∥≤k(τ) e ^{−γ(τ)(t−t0)}∥x ₀∥, with x _τ(t, t ₀, x ₀) the solution of the parametrized system with initial state x ₀ at t ₀. We show that for α sufficiently large is exponentially stable when “on average”γ(τ) is positive. The use of this result is illustrated by means of two examples. First, we extend the circle criterion. Second, exponential stability for a pendulum with a nonlinear slowly time-varying friction attaining positive and negative values is discussed. Date received: January 22, 2000. Date revised: April 14, 2001.     

Classroom context and teachers' perceptions of problem behaviors.

73 teachers of kindergarten to 8th grade viewed disruptive- or nondisruptive-context videotaped vignettes and rated each portrayal in terms of severity, manageability, tolerance, and contagion to investigate the effects of context on Ss' perceptions of 5 problem behaviors (blaming, poor peer cooperation, negative aggression, inattention, and failure anxiety). ANCOVA showed that contagion yielded significant differences (stronger within the disruptive context), suggesting that the target child was held responsible for the classroom disorder. Correlational data explained the relationship between the 4 areas, suggesting a dichotomy between quality (type of behavior) and quantity (degree or severity of behavior) for interpreting perceptions. Low tolerance was associated with higher levels of severity and more outer-directed behaviors. Contagion had more active, observable components and was related more to the qualitative dimension. Manageability (also active, observable, and teacher centered) was strongly influenced by quantitative factors (greater extremes of atypical behavior). (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Secretarial attitudes towards word processors as a function of familiarity and locus of control

The purpose of the present study was to investigate dimensions of secretarial anxiety, eagerness, and curiosity with respect to word processing equipment. Such variables as familiarity, formal training, physical proximity to the equipment, degree of influence in the decision to acquire a word processor, and frequency of use were seen as potential predictors of such attitudes. Additionally, two trait-like dimensions were measured, locus of control and complexity. Questionnaires were sent to 408 secretaries employed at a mid-western university. The response rate was 59 per cent (n = 241). People who had not used word processing equipment were more anxious than those individuals who had. Moreover, frequency of use for people with experience was related to greater change in anxiety levels. While familiarity reduced anxiety, it also tended to reduce curiosity. Frequency of word processor use was related to several variables. For instance, frequency of use was related to how positively the person evaluated the processor as affecting their work capabilities. Heavy users felt that the manuals were less helpful. Internally controlled individuals were more eager, curious and less anxious, while cognitively complex individuals were more curious about word processors. The applied implications of the findings are discussed.     

Subdoctoral education in psychology: A study of issues and attitudes.

Discusses several psychological conferences and committee's attitudes toward the desirability of "programs to train for psychological service at less than the doctoral level." 7 central areas of contention concerning subdoctoral training are (1) type of training, (2) level of training, (3) responsibility for training, (4) locus of training, (5) degree and/or title, (6) roles and duties, and (7) implications for psychology. The 7 issues served as the basis of the specific questions in a large scale survey. The sample (N = 4308) included American Psychological Association members of the Clinical, School, and Counseling Divisions of Psychology and chairmen of graduate departments of psychology. Results indicate that "the large majority of psychologists recognize the need for and approve the training of people at less than the doctoral level to do psychological work." A consensus as to how this is to be implemented was not reached. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)