To examine colloid transport in geochemically heterogeneous porous media at a scale comparable to field experiments, we monitored the migration of silica-coated zirconia colloids in a two-dimensional layered porous media containing sand coated to three different extents by ferric oxyhydroxides. Transport of the colloids was measured over 1.65 m and 95 days. Colloid transport was modeled by an a...

Background. The precision and limitations of ventricular pacemapping as a method to localize the site of earliest breakthrough of ventricular tachycardia (VT) were investigated in a canine model of experimental myocardial infarction. Methods and Results. Forty-one episodes of VT induced in 10 animals were mapped using a standard grid of 64 endocardial and epicardial bipolar electrodes to determ...

BACKGROUND Endo-epicardial dissociation (EED) of electric activations resulting in transmural conduction of fibrillation waves (breakthroughs) has been postulated to contribute to the complexity of the substrate of atrial fibrillation (AF). The aim of this study was to elucidate the correlation between EED and incidence of breakthrough and to test the plausibility of transmural conduction versu...

PURPOSE We constructed a risk prediction instrument stratifying patients with primary vesicoureteral reflux into groups according to their 2-year probability of breakthrough urinary tract infection. MATERIALS AND METHODS Demographic and clinical information was retrospectively collected in children diagnosed with primary vesicoureteral reflux and followed for 2 years. Bivariate and binary log...

How can companies simultaneously excel at today’s business while building tomorrow’s? It is a delicate organizational task. But new principles based on five years of research show that established organizations can build new futures when they design breakthrough new business units so that they can forget, borrow, and learn. Creating the future requires both breakthrough ideas and breakthrough e...

“Space drives,” “Warp drives,” and “Wormholes:” these concepts may sound like science fiction, but they are being written about in reputable journals. To assess the implications of these emerging prospects for future spaceflight, NASA supported the Breakthrough Propulsion Physics Project from 1996 through 2002. This project has three grand challenges: (1) Discover propulsion that eliminates the...

Treatment of chronic non-cancer pain with opioid therapy has escalated in recent years, resulting in exploding therapeutic use and misuse of prescription opioids and multiple adverse drug events. Breakthrough pain is defined as a transient exacerbation of pain experienced by individuals who have relatively stable and adequately controlled baseline cancer pain. Further, the definition of breakth...

[1] Tracer buoyancy has been shown to influence breakthrough from two-well tracer experiments conducted in porous media. Two-well tracer experiments are presented from fractured crystalline bedrock, in which the specific gravity of the tracer injectate varied from 1.0002 to 1.0133. Under the forced hydraulic conditions imposed, no difference in breakthrough was noted for the three experiments. ...