103 research outputs found
Dynamics of a bouncing dimer
We investigate the dynamics of a dimer bouncing on a vertically oscillated
plate. The dimer, composed of two spheres rigidly connected by a light rod,
exhibits several modes depending on initial and driving conditions. The first
excited mode has a novel horizontal drift in which one end of the dimer stays
on the plate during most of the cycle, while the other end bounces in phase
with the plate. The speed and direction of the drift depend on the aspect ratio
of the dimer. We employ event-driven simulations based on a detailed treatment
of frictional interactions between the dimer and the plate in order to
elucidate the nature of the transport mechanism in the drift mode.Comment: 4 pages, 5 figures, Movies:
http://physics.clarku.edu/~akudrolli/dime
Dynamic buckling and fragmentation in brittle rods
We present experiments on the dynamic buckling and fragmentation of slender
rods axially impacted by a projectile. By combining the results of Saint-Venant
and elastic beam theory, we derive a preferred wavelength lambda for the
buckling instability, and experimentally verify the resulting scaling law for a
range of materials including teflon, dry pasta, glass, and steel. For brittle
materials, buckling leads to the fragmentation of the rod. Measured fragment
length distributions show two clear peaks near lambda/2 and lambda/4. The
non-monotonic nature of the distributions reflect the influence of the
deterministic buckling process on the more random fragmentation processes.Comment: 4 pages, 5 figures, submitted to Physical Review Letter
Impact testing to determine the mechanical properties of articular cartilage in isolation and on bone
The original publication is available at www.springerlink.comNon peer reviewedPostprin
Evaluating teaching effectiveness in nursing education:An Iranian perspective
BACKGROUND: The main objective of this study was to determine the perceptions of Iranian nurse educators and students regarding the evaluation of teaching effectiveness in university-based programs. METHODS: An exploratory descriptive design was employed. 143 nurse educators in nursing faculties from the three universities in Tehran, 40 undergraduate, and 30 graduate students from Tehran University composed the study sample. In addition, deans from the three nursing faculties were interviewed. A researcher-developed questionnaire was used to determine the perceptions of both faculty and students about evaluating the teaching effectiveness of nurse educators, and an interview guide was employed to elicit the views of deans of faculties of nursing regarding evaluation policies and procedures. Data were analyzed using parametric and nonparametric statistics to identify similarities and differences in perceptions within the Iranian nurse educator group and the student group, and between these two groups of respondents. RESULTS: While faculty evaluation has always been a major part of university based nursing programs, faculty evaluation must be approached more analytically, objectively, and comprehensively to ensure that all nursing educators receive the fairest treatment possible and that the teaching-learning process is enhanced. CONCLUSION: Educators and students stressed that systematic and continuous evaluation as well as staff development should be the primary goals for the faculty evaluation process. The ultimate goals is the improvement of teaching by nurse educators
Evidence based practice in clinical physiotherapy education: a qualitative interpretive description
The numerical method for three-dimensional impact with friction of multi-rigid-body system
Analysis of rolling friction effects on oblique rebound by redefining tangential restitution and friction
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