Potato gun ocular injury

PURPOSE: This study aimed to identify a dangerous new weapon capable of causing damage to the ocular and periocular regions. METHODS: The authors report two patients who had penetrating ocular injury in the past year because of homemade recreational potato guns. RESULTS: In one 14-year-old boy, projectiles from the firing of a potato gun resulted in orbital and cranial injuries that were life threatening with widespread fractures, marked disruption of facial structures, a cerebrospinal fluid fistula requiring bifrontal surgical repair, and loss of one eye. In a separate accident with a different potato gun, a 14-year-old boy who was wearing glasses at the time of injury had a sight-threatening perforating corneal laceration. CONCLUSION: Practitioners must be aware of the existence of these new, homemade unregulated devices. Information about the use and construction of these guns is widespread on the Internet, but no injuries resulting from these guns currently are documented in the medical literature.     

Dimensional analysis of ionic transport problems in hydrated cement systems: Part 1. Theoretical considerations

The validity of the local equilibrium assumption in hydrated cement systems that a particular chemical reaction is instantaneous with respect to transport is examined using a dimensional analysis of electrochemical transport in cementitious materials. The transport equation parameters are scaled, resulting in a dimensionless equation. The dimensionless coefficient for each reaction/transport term determines its relative contribution to the overall process. The diffusion of ions in a reactive porous medium can be fully described on the basis of six independent dimensionless numbers. The analysis demonstrates that the kinetics of the reaction determine the appropriate time constant for the analysis. The formalism is applied to the dissolution of calcium hydroxide under an electrochemical potential gradient. The results are in agreement with previous observations and demonstrate quantitatively the local equilibrium hypothesis is valid in most practical cases where ions are transported by diffusion through a saturated material.     

Application of single-level,pointwise algebraic,and smoothed aggregation multigrid methods to direct numerical simulations of incompressible turbulent flows

Single- and multi-level iterative methods for sparse linear systems are applied to unsteady flow simulations via implementation into a direct numerical simulation solver for incompressible turbulent flows on unstructured meshes. The performance of these solution methods, implemented in the well-established SAMG and ML packages, are quantified in terms of computational speed and memory consumption, with a direct sparse LU solver (SuperLU) used as a reference. The classical test case of unsteady flow over a circular cylinder at low Reynolds numbers is considered, employing a series of increasingly fine anisotropic meshes. As expected, the memory consumption increases dramatically with the considered problem size for the direct solver. Surprisingly, however, the computation times remain reasonable. The speed and memory usage of pointwise algebraic and smoothed aggregation multigrid solvers are found to exhibit near-linear scaling. As an alternative to multi-level solvers, a single-level ILUT-preconditioned GMRES solver with low drop tolerance is also considered. This solver is found to perform sufficiently well only on small meshes. Even then, it is outperformed by pointwise algebraic multigrid on all counts. Finally, the effectiveness of pointwise algebraic multigrid is illustrated by considering a large three-dimensional direct numerical simulation case using a novel parallelization approach on a large distributed memory computing cluster.     

The contribution of parental discipline, parental monitoring, and school risk to early-onset conduct problems in African American boys and girls.

The association of parental discipline and monitoring with the early conduct problems of 123 boys and girls was assessed in a highly disadvantaged, African American sample. Prospective analyses indicated that, after earlier conduct problems were controlled for, coercive parent discipline and poor parental monitoring at age 4? were independent, reliable predictors of age 6 conduct problems for both boys and girls. The association of parental monitoring with later child conduct problems was mediated, in part, by parents' choice of higher risk schools for their children's kindergarten education. The association of family income with child conduct problems was mediated by parental discipline and monitoring. These models are consistent with previous research on older, European American, more advantaged, male samples, which supports the generality of the association of family processes with child conduct problems across child gender, age, and ethnicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controllability perceptions and reactions to symptoms of schizophrenia: A within-family comparison of relatives with high and low expressed emotion.

In a sample of 35 family members of patients with recent-onset schizophrenia, attributions of control and the content of critical comments were compared for 2 relatives of the same household who held discrepant expressed emotion (EE) attitudes (1 high and 1 low) toward their mentally ill family member. Attributions and the content of critical comments were also compared for low-EE relatives from low-EE homes versus low-EE relatives from high-EE homes. Our results indicate that high-EE relatives tend to attribute more control over behavior to patients than do low-EE relatives of the same patient. In addition, low-EE relatives from high-EE homes attribute more behavioral control to patients than do low-EE relatives from low-EE homes. These findings suggest that EE status is linked to attributions of control over behaviors, but additional patient factors or influences among family members may also affect EE attitudes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ReliaCloud‐NS: A scalable web‐based simulation platform for evaluating the reliability of cloud computing systems

This paper discusses the implementation, architecture, and use of a graphical web‐based application called ReliaCloud‐NS that allows users to (1) evaluate the reliability of a cloud computing system (CCS) and (2) design a CCS to a specified reliability level for both public and private clouds. The software was designed with a RESTful application programming interface for performing nonsequential Monte Carlo simulations to perform reliability evaluations of a CCS. Simulation results are stored and presented to the user in the form of interactive charts and graphs from within a web browser. The software contains multiple types of CCS components, simulations, and virtual machine allocation schemes. ReliaCloud‐NS also contains a novel feature that evaluates CCS reliability across a range of varying virtual machine allocations and establishes and graphs a CCS reliability curve. This paper discusses the software architecture, the interactive web‐based interface, and the different types of simulations available in ReliaCloud‐NS and presents an overview of the results generated from a simulation.     

Optimal actuation of nonlinear resonant systems

In this study, we examine a new approach for actuation of dynamical systems with minimum work and maximum amplitude while maintaining constraints on the actuation force. Two methodology issues are addressed in the paper: sensitivity analysis about the nonlinear transient response and exploration of the strongly nonlinear relationship between the two objectives and the actuation design variables. The optimization analysis is carried out on lightly damped Duffing systems. The formulation of the optimization problem is found ideally suited to resolve the difficulty of dependence of response on initial conditions. The tradeoff curve of work and amplitude is computed. The optimal actuation strove to compensate for the limited force amplitude by an abrupt change in the force in time. Finally the optimization procedure is demonstrated on the kinematic design of hovering insect flight. The optimal design gives 50% reduction in power consumption, with a larger cutback for an actuation with high acceleration.     

Fast Global Illumination on Dynamic Height Fields

We present a real-time method for rendering global illumination effects from large area and environmental lights on dynamic height fields. In contrast to previous work, our method handles inter-reflections (indirect lighting) and non-diffuse surfaces. To reduce sampling, we construct one multi-resolution pyramid for height variation to compute direct shadows, and another pyramid for each indirect bounce of incident radiance to compute inter-reflections. The basic principle is to sample the points blocking direct light, or shedding indirect light, from coarser levels of the pyramid the farther away they are from a given receiver point. We unify the representation of visibility and indirect radiance at discrete azimuthal directions (i.e., as a function of a single elevation angle) using the concept of a "casting set" of visible points along this direction whose contributions are collected in the basis of normalized Legendre polynomials. This analytic representation is compact, requires no precomputation, and allows efficient integration to produce the spherical visibility and indirect radiance signals. Sub-sampling visibility and indirect radiance, while shading with full-resolution surface normals, further increases performance without introducing noticeable artifacts. Our method renders 512×512 height fields (> 500K triangles) at 36Hz.