Transcatheter Versus Surgical Closure of Perimembranous Ventricular Septal Defects in Children A Randomized Controlled Trial

ObjectivesThe objective of this study was to evaluate the safety and efficacy of the surgical versus transcatheter approach to correct perimembranous ventricular septal defects (pmVSDs) in a prospective, randomized, controlled clinical trial.BackgroundpmVSD is a common congenital heart disease in children. Surgical closure of pmVSD is a well-established therapy but requires open-heart surgery with cardiopulmonary bypass. Although the transcatheter approach is associated with significant incidence of complete atrioventricular block, it may provide a less invasive alternative. Critical comparison of the safety and efficacy of the 2 interventions necessitates a prospective, randomized, controlled trial.MethodsBetween January 2009 and July 2010, 229 children with pmVSD were randomly assigned to surgical or transcatheter intervention. Clinical, laboratory, procedural, and follow-up data over a 2-year period were compared.ResultsNeither group had mortality or major complications. However, statistical analysis of the 2 groups demonstrated significant differences (p < 0.001) in minor adverse events (32 vs. 7), quantity of blood transfused, duration of the procedure, median hospital stay, median intensive care unit stay, median hospitalization cost, and median blood loss. During a median follow-up of 2 years, the left ventricular end-diastolic dimension of both groups returned to normal and there was no difference in closure rate, adverse events, and complications between groups.ConclusionsTranscatheter device closure and surgical repair are effective interventions with excellent midterm results for treating pmVSD in children. Transcatheter device closure has a lower incidence of myocardial injury, less blood transfused, faster recovery, shorter hospital stay, and lower medical expenses. (Transcatheter Closure Versus Surgery of Perimembranous Ventricular Septal Defects; NCT00890799

Reconstructing High-Precision Coral Reef Geomorphology from Active Remote Sensing Datasets: A Robust Spatial Variability Modified Ordinary Kriging Method

Active remote sensing technology represented by multi-beam and lidar provides an important approach for the effective acquisition of underwater coral reef geomorphological information. A spatially continuous surface model of coral reef geomorphology reconstructed from active remote sensing datasets can provide important geomorphological parameters for the research of coral reef geomorphological and ecological changes. However, the surface modeling methods commonly used in previous studies, such as ordinary kriging (OK) and natural neighborhood (NN), often represent a “smoothing effect”, which causes the strong spatial variability of coral reefs to be imprecisely reflected by the reconstructed surfaces, thus affecting the accurate calculation of subsequent geomorphological parameters. In this study, a spatial variability modified OK (OK-SVM) method is proposed to reduce the impact of the “smoothing effect” on the high-precision reconstruction of the complex geomorphology of coral reefs. The OK-SVM adopts a collaborative strategy of global parameter transformation, local residual correction, and extremum correction to modify the spatial variability of the reconstructed model, while maintaining high local accuracy. The experimental results show that the OK-SVM has strong robustness to spatial variability modification. This method was applied to the geomorphological reconstruction of the northern area of a coral atoll in the Nansha Islands, South China Sea, and the performance was compared with that of OK and NN. The results show that OK-SVM has higher numerical accuracy and attribute accuracy in detailed morphological fidelity, and is more adaptable in the geomorphological reconstruction of coral reefs with strong spatial variability. This method is relatively reliable for achieving high-precision reconstruction of complex geomorphology of coral reefs from active remote sensing datasets, and has potential to be extended to other geomorphological reconstruction applications

Characteristics of Strain-Induced In(x)Gai(1-x)As Nanowires Grown on Si(111) Substrates

Large strain-energy arising from lattice mismatch allows one-dimensional heteroepitaxial growth of In(chi)Gal(1-chi)As on silicon substrates without any catalyst or pattern assistance. In this paper, we show that in contrast to nanowires (NWs) grown by metal-catalyzed vapor-liquid-solid mechanism, strain-induced In chi Ga1-chi As NWs have several unique morphological features including no tapering, slight bending, and composition-dependent NW height saturation. Although small fluctuation exists, no systematic composition variations are observed over the entire In chi Ga1-chi As NW length within the resolution of the energy-dispersive X-ray spectroscopy analysis.close10

Wafer-Scale Production of Uniform InAsyP1-y Nanowire Array on Silicon for Heterogeneous Integration

One-dimensional crystal growth allows the epitaxial integration of compound semiconductors on silicon (Si), as the large lattice-mismatch strain arising from heterointerfaces can be laterally relieved. Here, we report the direct heteroepitaxial growth of a mixed anion ternary InAsyP1-y nanowire array across an entire 2 in. Si wafer with unprecedented spatial, structural, and special uniformity across the entire 2 in. wafer and dramatic improvements in aspect ratio (>100) and area density (>5 ?? 10 8/cm2). Heterojunction solar cells consisting of n-type InAsyP1-y (y = 0.75) and p-type Si achieve a conversion efficiency of 3.6% under air mass 1.5 illumination. This work demonstrates the potential for large-scale production of these nanowires for heterogeneous integration of optoelectronic devices.close9