Adhesion as an interplay between particle size and surface roughness

Abstract Surface roughness plays an important role in the adhesion of small particles. In this paper we have investigated adhesion as a geometrical effect taking into account both the particle size and the size of the surface features. Adhesion is studied using blunt model particles on surfaces up to 10 nm root-mean-square (RMS) roughness. Measurements with particles both smaller and larger than surface features are presented. Results indicate different behavior in these areas. Adhesion of particles smaller than or similar in size to the asperities depend mainly on the size and shape of the asperities and only weakly on the size of the particle. For large particles also the particle size has a significant effect on the adhesion. A new model, which takes the relative size of particles and asperities into account, is also derived and compared to the experimental data. The proposed model predicts adhesion well over a wide range of particle/asperity length scales

The KiVa antibullying curriculum and outcome: Does fidelity matter?

Research on school-based prevention suggests that the success of prevention programs depends on whether they are implemented as intended. In antibullying program evaluations, however, limited attention has been paid to implementation fidelity. The present study fills in this gap by examining the link between the implementation of the KiVa antibullying program and outcome. With a large sample of 7413 students (7&ndash;12 years) from 417 classrooms within 76 elementary schools, we tested whether the degree of implementation of the student lessons in the KiVa curriculum was related to the effectiveness of the program in reducing bullying problems in classrooms. Results of multilevel structural equation modeling revealed that after nine months of implementation, lesson adherence as well as lesson preparation time (but not duration of lessons) were associated with reductions in victimization at the classroom level. No statistically significant effects, however, were found for classroom-level bullying. The different outcomes for victimization and bullying as well as the importance of documenting program fidelity are discussed.</p

Measuring the hedonic and utilitarian sources of consumer attitudes

It has been suggested theoretically that consumer attitudes have distinct hedonic and utilitarian components, and that product categories differ in the extent to which their overall attitudes are derived from these two components. This paper reports three studies that validate measurement scales for these constructs and, using them, show that these two attitude dimensions do seem to exist; are based on different types of product attributes; and are differentially salient across different consumer products and behaviors, in theoretically-consistent ways.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47067/1/11002_2004_Article_BF00436035.pd