Ocean barrier layers' effect on tropical cyclone intensification

Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.     

Six year follow-up after catheter ablation of atrial fibrillation: a palliation more than a true cure

Long-term outcomes after pulmonary vein isolation for atrial fibrillation (AF) remain uncertain. In particular, the influence of rigorous arrhythmia monitoring on outcomes is not yet clear. In this study, 103 patients with symptomatic AF who underwent catheter ablation at a single academic medical center from 2002 to 2006 were evaluated, with a median follow-up time of 6 years. The primary end point was the success rate of catheter ablation, defined as the absence of any atrial arrhythmia recurrence lasting >10 seconds at the clinical visit and electrocardiographic or long-term cardiac rhythm recording after a single procedure and after the last procedure. In all, 153 procedures were performed, with a median of 1 (interquartile range 1 to 2) per patient as follows: 61 had 1, 35 had 2, 6 had 3, and 1 had 4 catheter ablations. Freedom from all atrial arrhythmias was present in 23% of patients at 6 years after a single procedure and in 39% of patients after the last procedure. No clinical predictors of AF recurrence were recognized after a single procedure, whereas after the last procedure, in univariate and multivariate Cox regression analysis, only nonparoxysmal AF (hazard ratio 1.92, 95% confidence interval 1.07 to 3.47, p = 0.02) was a predictor of recurrence. In conclusion, AF recurrence at 6-year follow-up after catheter ablation in a selected group of patients with symptomatic drug-refractory AF was relatively high, with 2/3 of AF relapses occurring in the first year of follow-up. Strict clinical surveillance after catheter ablation should be considered to help guide clinical decisions.     

Predictors of poor dental arch relationship in young children with unilateral cleft lip and palate

The aim of this cross-sectional outcome study using retrospective data capture of treatment histories was to examine the characteristics of young children with unilateral cleft lip and palate who had poor dental arch relationship (i.e., Goslon 5). The study sample comprised 120 children born with nonsyndromic complete unilateral cleft lip and palate between 1995 and 2003, and were aged between 5.0 and 7.0 years (mean age, 5.1 years) at the time of data collection. The dental arch relationship was assessed using the Goslon yardstick from intraoral dental photographs. An independent investigator recorded treatment histories from the clinical notes. The inter- and intraexaminer agreements evaluated by weighted kappa statistics were high. There was no association between dental arch relationship and the type of presurgical orthopedics or pharyngeal flap. Dental arch relationship was associated with the initial cleft size (odds ratio, OR = 1.3; 95% confidence interval, CI = 1.1-1.5, p < 0.01), surgeon grade for palate repair (OR = 5.0, 95% CI = 1.2-19.9, p < 0.05), and primary gingivoperiosteoplasty (OR = 2.8, 95% CI = 1.0-8.1, p = 0.05). These data suggest that intraoral dental photographs provide a reliable method for rating dental arch relationship. Wide initial cleft, high-volume surgeon, and primary gingivoperiosteoplasty are predictors of poor dental arch relationship outcome in young children with unilateral cleft lip and palate. These findings may improve treatment outcome by modifying the treatment protocol for patients with unilateral cleft lip and palate.