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To investigate the merits of single versus multiple authorship in scholarly journals, several journals were examined regarding degrees of single versus multiple authorship, posture of multiple authorship, and author-article ratio of three physical education, recreation, and dance periodicals. The article discusses ramifications of the increasing trend toward multiple authorship. (SM)

Several factors have focused new attention on aging and the aged. A major concern emanating from these has been the role of physical fitness upon the health status of the aging. Benefits of exercise and educational and curricular modifications are identified to promote health and well-being among the elderly. (Author/BEF)

Using discrete particle simulations validated by experimental data acquired using the positron emission particle tracking technique, we study the efficiency of energy transfer from a vibrating wall to a system of discrete, macroscopic particles. We demonstrate that even for a fixed input energy from the wall, energy conveyed to the granular system under excitation may vary significantly dependent on the frequency and amplitude of the driving oscillations. We investigate the manner in which the efficiency with which energy is transferred to the system depends on the system variables and determine the key control parameters governing the optimization of this energy transfer. A mechanism capable of explaining our results is proposed, and the implications of our findings in the research field of granular dynamics as well as their possible utilization in industrial applications are discussed. [ABSTRACT FROM AUTHOR]

Abstract: We present self-diffusion calculations derived from discrete element simulations of an idealized granular material under gravity, which is energized through vertical, sinusoidal oscillations of a plane rigid floor. The bed of particles is agitated to a degree so that computed steady-state profiles of granular temperature and solids fraction are consistent with kinetic theory predictions. The average self-diffusivity for the entire assembly, computed both from the velocity autocorrelation function and the mean-square displacement, is found to compare well with an analytic expression taken from kinetic theory. [Copyright &y& Elsevier]

An investigation of the motion of a single particle rolling down a Galton's board is carried out using experiments, simulations and discrete dynamical models. The results obtained from the experimental simulation and discrete dynamical system approaches with regard to such properties as lateral diffusion coefficients and end distributions are found to be in reasonably good agreement. In addition, the existence of chaotic regimes is indicated by the experiments and simulations, and proven using the simple dynamical models for certain ranges of the key system parameters. [ABSTRACT FROM AUTHOR]

Investigates the behavior of a shallow bed of inelastic, frictional spheres which are energized by vertical sinusoidal oscillations of a plane floor. Long-term and instantaneous velocity fields; Evolution of the pressure tensor; Appearance of persistent vortices near vertical sidewalls.

Investigates macroscopic behavior of granular materials subjected to vibrations using three-dimensional granular dynamics simulations. Discrete element simulation model; Geometry and diagnostics; Comparison with kinetic theory predictions and experiments.

Demonstrates a nuclear magnetic resonance (NMR) imaging method to study highly energetic vibrating granular beds by spatial scanning. Importance of NMR as an experimental technique to study the behavior of moving granular materials; Ability to measure concentration, velocity and dissipation within the bulk granular materials.

In this paper, we compare the behaviours of two vibrofluidized granular systems, identical in terms of their composition, geometry and driving parameters, differing only in their initial conditions. It is found that, by increasing the strength with which a system is initially excited, considerable differences in system composition and dynamics persist even after the driving is returned to its typical value. The observed changes in particle mobility and packing density are shown to result in marked differences in segregative behaviour for equivalent steady-state systems distinguished only by the history of their driving. The ability to significantly increase the rate of segregation in a granular system simply through the application of a short burst of intense vibration clearly has potential industrial applications. [ABSTRACT FROM AUTHOR]

The decay of energy within particulate media subjected to an impulse is an issue of significant scientific interest, but also one with numerous important practical applications. In this paper, we study the dynamics of a granular system exposed to energetic impulses in the form of discrete taps from a solid surface. By considering a one-dimensional toy system, we develop a simple theory, which successfully describes the energy decay within the system following exposure to an impulse. We then extend this theory so as to make it applicable also to more realistic, three-dimensional granular systems, assessing the validity of the model through direct comparison with discrete particle method simulations. The theoretical form presented possesses several notable consequences; in particular, it is demonstrated that for suitably large systems, effects due to the bounding walls may be entirely neglected. We also establish the existence of a threshold system size above which a granular bed may be considered fully three dimensional. [ABSTRACT FROM AUTHOR]