Steven A. MacKay

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The motions of a large number (495) of preaggregative D. discoideum NC-4 cells in sparse fields are recorded on time-lapse film and analysed using a specially constructed computer graphics system. All films are produced under a standard set of conditions, so that the range of cell behaviours under given conditions can be characterized. The mean velocity of(More)
Refinement of a perfusion technique permitted the simultaneous measurement of cAMP-elicited [3H]cAMP secretion and intracellular [3H]cAMP levels in sensitive D. discoideum amoebae. These data were compared with measurements of the rate of [32P]cAMP synthesis by extracts of amoebae sonicated at different times during the cAMP signaling response. cAMP(More)
Post-smolt anadromous brown trout Salmo trutta, sea trout, from two Scottish west coast rivers, the Balgy and Shieldaig, flowing into adjacent sea lochs were tracked simultaneously using arrays of moored acoustic receivers to determine dispersal patterns and loss rates. Fish tended to stay close to their natal rivers for the first 14 day after entering the(More)
An accurate three-dimensional (3D) representation of heart wall motion would be an important means of evaluating cardiac function. To accomplish this, we have developed an interactive computer graphics system designed to enter the time-dependent 3D positions of bifurcations of the coronary arterial tree. These bifurcations are precise markers of the(More)
We have previously reported the detection of cAMP waves within monolayers of aggregating Dictyostelium discoideum cells (K. J. Tomchik and P.N. Devreotes, 1981, Science 212, 443-446). The computer-assisted analysis presented here of the fluorographic images of the cAMP waves reveals (1) all the waves have a consistent width and height; (2) cAMP(More)
We have studied the three-dimensional (3D) motion of left ventricular (LV) epicardial points by tracking one to three dozen coronary artery bifurcations in eleven human subjects. Wall motion was analyzed using several different coordinate systems: (1) cylindrical centered about the LV long axis, (2) spherical with origin at the LV center-of-gravity (COG),(More)
We describe an interactive graphics system for the entry of three-dimensional moving points from multiple perspective views. This work represents a major extension of Galatea, our system for graphics-assisted 2D motion analysis. 3D Galatea permits reconstruction of 3D time-dependent positions from 2D entries in two or more perspective views. The system(More)
Cardiac wall motion has been studied extensively. It is usually determined by indirect two-dimensional measurements for the true three-dimensional (3D) motion with its specific speed and direction. Errors are also introduced by using internally fixed reference systems and by the inability to identify precise points on the heart wall during the cardiac(More)