Jonathan C. Hardwick

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Cardiac output is regulated by the coordinate interactions of stimulatory sympathetic and inhibitory parasympathetic signals. Intracardiac parasympathetic ganglia are integrative centers of cardiac regulation, and modulation of the parasympathetic drive on the heart is accomplished by altering intrinsic cardiac ganglion neuron excitability. The pituitary(More)
This paper gives an overview of the implementation of NESL, a portable nested data-parallel language. This language and its implementation are the first to fully support nested data structures as well as nested data-parallel function calls. These features allow the concise description of parallel algorithms on irregular data, such as sparse matrices and(More)
The present study was done to establish whether peptidergic afferent inputs can modulate parasympathetic neurons of the guinea-pig cardiac ganglion. Whole mount preparations from the guinea-pig heart were utilized to localize afferent terminals by immunohistochemistry and for intracellular recordings from individual neurons in situ. Action potentials could(More)
1. Whole mount preparations from guinea-pig hearts were used to characterize the receptors and ionic mechanisms mediating the substance P (SP)-induced depolarization of parasympathetic postganglionic neurones of the cardiac ganglion. 2. Measurement of the amplitude of depolarization in response to superfusion of different tachykinin agonists (neurokinins A(More)
This paper describes the derivation of an empirically efficient parallel two-dimensional Delaunay triangulation program from a theoretically efficient CREW PRAM algorithm. Compared to previous work, the resulting implementation is not limited to dataaets with a uniform dktribution of points, achieves significantly better speedups over good serial code, and(More)
This paper presents work in progress on a new method of implementing irregular divide-and-conquer algorithms in a nested data-parallel language model on distributedmemory multiprocessors. The main features discussed are the recursive subdivision of asynchronous processor groups to match the change from data-parallel to control-parallel behavior over the(More)
Our understanding of PACAP expression and regulation of sympathetic neuronal function has been augmented considerably over the last few years. Among the three major VIP/PACAP receptor subtypes, the SCG appears to express preferentially one particular variant of the PACAP-selective PACAP1 receptor coupled to multiple intracellular signaling cascades. The in(More)
1. Our previous studies demonstrated that protein kinase C (PKC) activity is required for acetylcholine (ACh) sensitivity to recover fully at snake twitch fiber end plates after prolonged exposure to carbachol. In the present studies, we have investigated whether protein phosphatase(s), activated during carbachol exposure, dephosphorylated critical membrane(More)
Guinea pig atrial whole mount preparations containing the parasympathetic cardiac ganglia were used to establish the expression, distribution and actions of neuropeptide Y (NPY) in atrial tissues. NPY-immunoreactive fibers densely innervated the atrial myocardium and blood vessels. Fibers containing NPY also innervated intrinsic parasympathetic cardiac(More)
This paper describes the design and implementation of a practical parallel algorithm for Delaunay triangulation that works well on general distributions. Although there have been many theoretical parallel algorithms for the problem, and some implementations based on bucketing that work well for uniform distributions, there has been little work on(More)