David Calhoun

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The effects of propantheline bromide (PB), cimetidine (CM) and thiopropazate hydrochloride (TP) on the course of stress ulcer formation were investigated. Gastric ulcers were induced by subjecting rats to forced exertion. Intragastric administration of PB, CM or TP produced dose-dependent inhibition of gastric ulceration with parallel dose-response curves.(More)
The rising popularity of cloud computing and big data applications has led to massive volumes of rack-to-rack traffic featuring diverse communication patterns denoted as *-cast that combines unicast, multicast, incast and all-to-all cast. Effective support of these traffic patterns in data center networks is still an open problem. We propose a hybrid(More)
With the rapidly increasing aggregate bandwidth requirements of data centers there is a growing interest in the insertion of optically interconnected networks with high-radix transparent optical switch fabrics. Silicon photonics is a particularly promising and applicable technology due to its small footprint, CMOS compatibility, high bandwidth density, and(More)
Cellular senescence is an irreversible growth phase characteristic of normal cells. We have found that human senescent fibroblasts can be induced to undergo programmed cell death (apoptosis) by ceramide, TNF-alpha, or okadaic acid. The most profound effects were induced by TNF-alpha and okadaic acid treatment. In the present study, we also evaluated the(More)
—Silicon photonic interconnection networks can provide significant advantages in bandwidth densities and data communication energy efficiencies over electronic-interconnected systems. However, due to the circuit switched nature of photonics, the latencies associated with circuit setup and reconfiguration must be managed to avoid added delays in application(More)
—Optical interconnects, which support the transport of large bandwidths over warehouse-scale distance, can help to further scale data-movement capabilities in high performance computing (HPC) platforms. However, due to the circuit switching nature of optical systems and additional peculiarities, such as sensitivity to temperature and the need for wavelength(More)
We test a high-resolution wave-propagation algorithm for hyperbolic conservation laws on mapped quadrilateral and hexahedral grids in the context of adaptive mesh refinement. We discuss some of the issues related to using non-Cartesian grids with AMR and study a test problem in which a grid refinement interface is fixed in space on a highly skewed portion(More)