David Calhoun

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—With the extraordinary growth in parallelism at all system scales driven by multicore architectures, computing performance is increasingly determined by how efficiently high-bandwidth data is communicated among the numerous compute resources. High-performance systems are especially challenged by the growing energy costs dominated by data movement. As(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)
—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)
Left ventricular hypertrophy and diastolic dysfunction (LVDD) remain highly frequent markers of cardiac damage and risk of progression to symptomatic heart failure, especially in resistant hypertension (RHTN). We have previously demonstrated that administration of sildenafil in hypertensive rats improves LVDD, restoring phosphodiesterase type 5 (PDE-5)(More)
—iOS is Apple's mobile operating system and is presently used on the iPhone, iPad, and iPod Touch. The hardware platforms associated with the iOS operating system provide a powerful platform for sensor applications. In this paper, we provide a case study on the development of a digital multimeter (DMM) using an iPod Touch. The DMM case study addresses the(More)
Background—Vascular endothelial function declines with advancing age, due in part to increased oxidative stress and inflammation, and this age-related vascular dysfunction has been identified as an independent risk factor for cardiovascular diseases (CVD). This double-blind, placebo-controlled trial investigated the effects of a dietary supplement(More)
Background—Increased relative wall thickness in hypertensive left ventricular hypertrophy (LVH) has been shown by echocardiography to allow preserved shortening at the endocardium despite depressed LV midwall circumferential shortening (MWCS). Depressed MWCS is an adverse prognostic indicator, but whether this finding reflects reduced global or regional LV(More)
  • Ambika P. Ashraf, Jessica A. Alvarez, Tanja Dudenbostel, David Calhoun, Russell Griffin, Xudong Wang +2 others
  • 2014
OBJECTIVE The role of vitamin D in cardiovascular health remains debated as results have been inconsistent. Previous studies have not considered the bioavailability of 25-hydroxy vitamin D [25(OH)D]. Objectives of our study were to investigate the association between serum concentrations of total, free and bioavailable 25(OH)D and independent predictors of(More)