The myocardial and coronary histopathology and pathogenesis of hypoplastic left heart syndrome

AbstractHypoplastic left heart syndrome has the greatest mortality rate among all CHDs and without palliation is uniformly fatal. Despite noble efforts, the aetiology of this syndrome is unknown and a cure remains elusive. The genetic and anatomic heterogeneity of hypoplastic left heart syndrome supports a rethinking of old hypotheses and warrants further investigation into the histological and vascular variations recognised with this syndrome. In an effort to elucidate the pathogenesis of hypoplastic left heart syndrome, this review will focus on its unique myocardial and coronary pathology as well as evaluate the association of hypoplastic left heart syndrome with the endocardial fibroelastosis reaction.</jats:p

Prediction of Cooling Air Flow in Electric Generators

The cooling air flow in hydro power electric generators is investigated experimentally and numerically. A fully predictive numerical approach is presented and validated, in which the inlet and outlet boundaries are eliminated from the computational domain. Instead, a part of the space outside the machine is included in the computational domain, allowing for recirculation of the cooling air. The predicted flow is therefore driven solely by the rotation of the rotating parts of the generator. In this way, the predicted flow field is independent of any experimental data at the inlet, and is determined completely by the solution. Using the fully predictive approach, a number of parametric numerical studies are performed on the rotor and stator geometries. The effect of adding geometrical details to the rotor and stator are investigated, and stator baffles and rotor fan blades are concluded to increase the volume flow rate through the machine. The volume flow rate through the machine is found to vary linearly with the rotor rotational speed, while the required rotor axial power increases cubically with the rotor rotational speed. The numerical results are validated against experimental measurements in a real electric generator. Flow visualizations, and 5-hole probe and total pressure measurements are performed. A comparison of the numerical results and the experimental data reveals a good qualitative prediction of the flow by the fully predictive numerical approach. The sensitivity of the numerical results to different choices of inlet boundary conditions is also investigated. The level of detail in the boundary conditions proves to play an important role in predicting correct flow features. A half-scale laboratory model, based on the above studied electric generator, is specifically designed and manufactured for experimental studies of the cooling air flow. The measurement accuracy in the half-scale model is significantly improved compared to that in the real generator. The model is provided with static pressure holes and optical access for flow measurements using Particle Image Velocimetry (PIV). The fully predictive numerical approach is shown to yield quantitatively similar results as the experimental flow measurements. The numerical simulations are also performed with inlet and outlet boundary conditions, by specifying the inlet volume flow rates from the experimental measurements. The results of the fully predictive numerical approach are shown to agree better with the experimental data, than those of the simulations with inlet and outlet boundary conditions

Protein Docking by the Underestimation of Free Energy Funnels in the Space of Encounter Complexes

Similarly to protein folding, the association of two proteins is driven by a free energy funnel, determined by favorable interactions in some neighborhood of the native state. We describe a docking method based on stochastic global minimization of funnel-shaped energy functions in the space of rigid body motions (SE(3)) while accounting for flexibility of the interface side chains. The method, called semi-definite programming-based underestimation (SDU), employs a general quadratic function to underestimate a set of local energy minima and uses the resulting underestimator to bias further sampling. While SDU effectively minimizes functions with funnel-shaped basins, its application to docking in the rotational and translational space SE(3) is not straightforward due to the geometry of that space. We introduce a strategy that uses separate independent variables for side-chain optimization, center-to-center distance of the two proteins, and five angular descriptors of the relative orientations of the molecules. The removal of the center-to-center distance turns out to vastly improve the efficiency of the search, because the five-dimensional space now exhibits a well-behaved energy surface suitable for underestimation. This algorithm explores the free energy surface spanned by encounter complexes that correspond to local free energy minima and shows similarity to the model of macromolecular association that proceeds through a series of collisions. Results for standard protein docking benchmarks establish that in this space the free energy landscape is a funnel in a reasonably broad neighborhood of the native state and that the SDU strategy can generate docking predictions with less than 5 � ligand interface Ca root-mean-square deviation while achieving an approximately 20-fold efficiency gain compared to Monte Carlo methods

Times-History Finite Element Dynamic Analysis - Soil Nail Wall - San Manuel Casino - Highland, California

The site of the proposed Phase II Parking Facility at the San Manuel Resort Casino, Highland, California, is on a sloped terrain where there is a 35 ft. grade differential from the north to the south end of the planned structure. PB&A, Inc. was selected to design a 12,000 square foot Soil-Nailed wall with a maximum height of 37 ft. to protect the Parking Structure from the soil pressures resulting from sloping ground conditions at the site. The project site is located within 100 feet of the San Andreas Fault in the highly seismic Southern California region, characterized by numerous active faults and high level seismic activity. The alignment of the Soil-Nailed wall is located at the edge of the Alquist-Priolo Earthquake Fault Zone. The proximity of the Soil Nail Wall to this major seismic fault necessitated the preparation of a dynamic analysis to better assess the behavior of the wall during a seismic event. The main objective of this analysis was to determine the maximum deformation the Soil-Nailed Wall would undergo during an earthquake so that an adequate separation could be defined between the structure of the parking garage and the Soil-Nailed Wall. In addition, vertical soil nails (V-Nails) were to be installed directly behind the shotcrete facing of the wall to provide localized surface stability during construction. The effect of the V-Nails was to be studied in relationship to the overall performance of the wall. The Geotechnical Engineer of Record, Kleinfelder, provided three sets of spectra-matched outcropping acceleration time histories from three representative earthquakes: Duzce earthquake, Turkey (11/12/1999), Landers earthquake, United States (06/28/1992) and Chi-Chi earthquake, Taiwan China (09/20/1999). Using the information gleaned from these time histories, PB&A constructed a half-space model in PLAXIS, a Finite Element software application widely used in the industry. To construct the model, engineers used the Mohr-Columb soil model applied to layers of soil at the project site. The soil strength and stiffness parameters were based on the recommended values outlined in the Geotechnical Report and the shotcrete wall and soil nails were modeled with the plate (Beam) and ground anchor element, respectively. It was necessary to transform the acceleration time histories to the proper depth at the bottom of the PLAXIS model, as the acceleration time histories were recorded as the outcropping motions,. To accomplish this, the deconvolution process was performed in the SHAKE91 program. In the staged construction calculation, the horizontal and vertical displacement, velocity and acceleration are recorded at the top and the bottom of the wall in each step

3D Printing Provides a Precise Approach in the Treatment of Tetralogy of Fallot, Pulmonary Atresia with Major Aortopulmonary Collateral Arteries.

Patients with tetralogy of Fallot, pulmonary atresia, and multiple aortopulmonary collateral arteries (Tet PA MAPCAs) have a wide spectrum of anatomy and disease severity. Management of these patients can be challenging and often require multiple high-risk surgical and interventional catheterization procedures. These interventions are made challenging by complex anatomy that require the proceduralist to mentally reconstruct three-dimensional anatomic relationships from two-dimensional images. Three-dimensional (3D) printing is an emerging medical technology that provides added benefits in the management of patients with Tet PA MAPCAs. When used in combination with current diagnostic modalities and procedures, 3D printing provides a precise approach to the management of these challenging, high-risk patients. Specifically, 3D printing enables detailed surgical and interventional planning prior to the procedure, which may improve procedural outcomes, decrease complications, and reduce procedure-related radiation dose and contrast load

Application of Concave-Up P-Y Elements in Static Analysis of Piles in Laterally Spreading Ground

Concave-up p-y behavior in liquefied sand has been observed by many researchers due to the dilatant tendency of sand that is dense of its critical state being suppressed in undrained loading. However, static analysis method often scale down the concave-down p-y curves that characterize drained loading, thereby missing the potentially important influence of concave-up behavior on pile response. For lateral spreading problems, large shear strains are typically assigned to the liquefied layer, which presupposes that the liquefied sand is soft and weak. This assumption is incompatible with the strengthening, stiffening concave-up p-y material. This paper presents a static lateral spreading analysis of a pile using concave-up p-y materials to demonstrate how this incompatibility can lead to unrealistic results