Current Issues and Future Directions in Simulation-Based Training in North America

A number of emerging challenges including globalization, economic pressures, and the changing nature of work have combined to create a business environment that demands innovative, flexible training solutions. Simulations are a promising tool for creating more realistic, experiential learning environments to meet these challenges. Unfortunately, the current literature on simulation-based training paints a mixed picture as to the effectiveness of simulations as training tools, with most of the previous research focusing on the specific technologies used in simulation design and little theory-based research focusing on the instructional capabilities or learning processes underlying these technologies. This article examines the promise and perils of simulation-based training, reviews research that has examined the effectiveness of simulations as training tools, identifies pressing research needs, and presents an agenda for future theory-driven research aimed at addressing those needs

A Survey of Eclipsing Binary Stars in the Eastern Spiral Arm of M31

Results of an archival survey are presented using B-band imaging of the eastern spiral arm of M31. Focusing on the eclipsing binary star population, a matched-filter technique has been used to identify 280 binary systems. Of these, 127 systems (98 of which are newly discovered) have sufficient phase coverage to allow accurate orbital periods to be determined. At least nine of these binaries are detached systems which could, in principle, be used for distance determination. The light curves of the detached and other selected systems are presented along with a discussion of some of the more interesting binaries. The impact of unresolved stellar blends on these lightcurves is considered.Comment: 10 pages, accepted for publication in MNRA

GPU-based ultra-fast direct aperture optimization for online adaptive radiation therapy

Online adaptive radiation therapy (ART) has great promise to significantly reduce normal tissue toxicity and/or improve tumor control through real-time treatment adaptations based on the current patient anatomy. However, the major technical obstacle for clinical realization of online ART, namely the inability to achieve real-time efficiency in treatment re-planning, has yet to be solved. To overcome this challenge, this paper presents our work on the implementation of an intensity modulated radiation therapy (IMRT) direct aperture optimization (DAO) algorithm on graphics processing unit (GPU) based on our previous work on CPU. We formulate the DAO problem as a large-scale convex programming problem, and use an exact method called column generation approach to deal with its extremely large dimensionality on GPU. Five 9-field prostate and five 5-field head-and-neck IMRT clinical cases with 5\times5 mm2 beamlet size and 2.5\times2.5\times2.5 mm3 voxel size were used to evaluate our algorithm on GPU. It takes only 0.7~2.5 seconds for our implementation to generate optimal treatment plans using 50 MLC apertures on an NVIDIA Tesla C1060 GPU card. Our work has therefore solved a major problem in developing ultra-fast (re-)planning technologies for online ART

Stratigraphic Architecture of Bedrock Reference Section, Victoria Crater, Meridiani Planum, Mars

The Mars Exploration Rover Opportunity has investigated bedrock outcrops exposed in several craters at Meridiani Planum, Mars, in an effort to better understand the role of surface processes in its geologic history. Opportunity has recently completed its observations of Victoria crater, which is 750 m in diameter and exposes cliffs up to ∼15 m high. The plains surrounding Victoria crater are ∼10 m higher in elevation than those surrounding the previously explored Endurance crater, indicating that the Victoria crater exposes a stratigraphically higher section than does the Endurance crater; however, Victoria strata overlap in elevation with the rocks exposed at the Erebus crater. Victoria crater has a well-developed geomorphic pattern of promontories and embayments that define the crater wall and that reveal thick bedsets (3–7 m) of large-scale cross-bedding, interpreted as fossil eolian dunes. Opportunity was able to drive into the crater at Duck Bay, located on the western margin of Victoria crater. Data from the Microscopic Imager and Panoramic Camera reveal details about the structures, textures, and depositional and diagenetic events that influenced the Victoria bedrock. A lithostratigraphic subdivision of bedrock units was enabled by the presence of a light-toned band that lines much of the upper rim of the crater. In ascending order, three stratigraphic units are named Lyell, Smith, and Steno; Smith is the light-toned band. In the Reference Section exposed along the ingress path at Duck Bay, Smith is interpreted to represent a zone of diagenetic recrystallization; however, its upper contact also coincides with a primary erosional surface. Elsewhere in the crater the diagenetic band crosscuts the physical stratigraphy. Correlation with strata present at nearby promontory Cape Verde indicates that there is an erosional surface at the base of the cliff face that corresponds to the erosional contact below Steno. The erosional contact at the base of Cape Verde lies at a lower elevation, but within the same plane as the contact below Steno, which indicates that the material above the erosional contact was built on significant depositional paleotopography. The eolian dune forms exposed in Duck Bay and Cape Verde, combined with the geometry of the erosional surface, indicate that these outcrops may be part of a larger-scale draa architecture. This insight is possible only as a result of the larger-scale exposures at Victoria crater, which significantly exceed the more limited exposures at the Erebus, Endurance, and Eagle craters

Ultrasonic/Sonic Mechanisms for Drilling and Coring

Two apparatuses now under development are intended to perform a variety of deep-drilling, coring, and sensing functions for subsurface exploration of rock and soil. These are modified versions of the apparatuses described in Ultrasonic/Sonic Drill/Corers With Integrated Sensors (NPO-20856), NASA Tech Briefs, Vol. 25, No. 1 (January 2001), page 38. In comparison with the drilling equipment traditionally used in such exploration, these apparatuses weigh less and consume less power. Moreover, unlike traditional drills and corers, these apparatuses function without need for large externally applied axial forces

The effects of socioeconomic status and indices of physical environment on reduced birth weight and preterm births in Eastern Massachusetts

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Air pollution and social characteristics have been shown to affect indicators of health. While use of spatial methods to estimate exposure to air pollution has increased the power to detect effects, questions have been raised about potential for confounding by social factors.Methods: A study of singleton births in Eastern Massachusetts was conducted between 1996 and 2002 to examine the association between indicators of traffic, land use, individual and area-based socioeconomic measures (SEM), and birth outcomes ( birth weight, small for gestational age and preterm births), in a two-level hierarchical model.Results: We found effects of both individual ( education, race, prenatal care index) and area-based ( median household income) SEM with all birth outcomes. The associations for traffic and land use variables were mainly seen with birth weight, with an exception for an effect of cumulative traffic density on small for gestational age. Race/ethnicity of mother was an important predictor of birth outcomes and a strong confounder for both area-based SEM and indices of physical environment. The effects of traffic and land use differed by level of education and median household income.Conclusion: Overall, the findings of the study suggested greater likelihood of reduced birth weight and preterm births among the more socially disadvantaged, and a greater risk of reduced birth weight associated with traffic exposures. Results revealed the importance of controlling simultaneously for SEM and environmental exposures as the way to better understand determinants of health.This work is supported by the Harvard Environmental Protection Agency (EPA) Center, Grants R827353 and R-832416, and National Institute for Environmental Health Science (NIEHS) ES-0002

GPU-based fast gamma index calcuation

The gamma-index dose comparison tool has been widely used to compare dose distributions in cancer radiotherapy. The accurate calculation of gamma-index requires an exhaustive search of the closest Euclidean distance in the high-resolution dose-distance space. This is a computational intensive task when dealing with 3D dose distributions. In this work, we combine a geometric method with a radial pre-sorting technique , and implement them on computer graphics processing units (GPUs). The developed GPU-based gamma-index computational tool is evaluated on eight pairs of IMRT dose distributions. The GPU implementation achieved 20x~30x speedup factor compared to CPU implementation and gamma-index calculations can be finished within a few seconds for all 3D testing cases. We further investigated the effect of various factors on both CPU and GPU computation time. The strategy of pre-sorting voxels based on their dose difference values speed up the GPU calculation by about 2-4 times. For n-dimensional dose distributions, gamma-index calculation time on CPU is proportional to the summation of gamma^n over all voxels, while that on GPU is effected by gamma^n distributions and is approximately proportional to the gamma^n summation over all voxels. We found increasing dose distributions resolution leads to quadratic increase of computation time on CPU, while less-than-quadratic increase on GPU. The values of dose difference (DD) and distance-to-agreement (DTA) criteria also have their impact on gamma-index calculation time.Comment: 13 pages, 2 figures, and 3 table

Making sense of urban food festivals: cultural regeneration, disorder and hospitable cities

This article examines urban food festivals, and in doing so it carries out a case study of Nottingham’s Food and Drink Festival (NFDF). It contends that such festivals need to be understood in relation to local contexts, such as the reputation for alcohol-related disorder associated with Nottingham’s night-time economy. Rather than being used to attract tourism, NFDF was primarily directed at existing residents of Nottingham, where it sought to produce particular kinds of guests who would be able to invest in the city’s wider regeneration. Here, the article draws on recent academic work on hospitality in demonstrating how NFDF attempted to rebrand the city centre as a more hospitable place. It concludes by showing how visitors to NFDF exhibited a sense of generosity and pride, and argues that the meaning of urban food festivals cannot therefore simply be reduced to the logic of neoliberal governance