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The nongeneric six- and eightdimensional orbits of SO(4,2) are described in explicitly covariant way. relevant Hamiltonian dynamical systems constructed canonically quantized. It is shown that the resulting unitary representations conformal group fit into classification by Mack (G. Mack, Comm. Math. Phys. 55 (1977),1).

The cognitive walkthrough (Lewis et al. 1990; Polson et al. 1992a) is a usability inspection method that focuses on evaluating a design for ease of learning, particularly by exploration. This focus is motivated by the observation that many users prefer to learn software by exploration (Carroll and Rosson 1987; Fischer 199 1). Instead of investing time for comprehensive formal training when a s ...

"Bone density is an important and little-investigated variable about which we should like to know more" (American Journal of Physical Anthropology, 1954). Here an anthropologist echoed a nutritionist (Nutrition Reviews, 1952) regarding photoelectric densitometer estimates of x-ray opacity expressed as thickness of an aluminium or ivory step-wedge (or bone slabs) exposed on the same film as a li...

In any society, professional or otherwise, certain individuals stand out by virtue of their ability, leadership qualities, other personal attributes, or combinations thereof. Mack Fulwyler had all of these but somehow even more. His philosophy of life, revealed in the manner with which he dealt with others, reminded one of Henry Thoreau with respect to the grandeur of nature, Thomas Edison with...