Implications of Shock Wave Experiments with Precompressed Materials for Giant Planet Interiors

This work uses density functional molecular dynamics simulations of fluid helium at high pressure to examine how shock wave experiments with precompressed samples can help characterizing the interior of giant planets. In particular, we analyze how large of a precompression is needed to probe a certain depth in a planet's gas envelope. We find that precompressions of up to 0.1, 1.0, 10, or 100 GPa are needed to characterized 2.5, 5.9, 18, to 63% of Jupiter's envelope by mass.Comment: Submitted As Proceedings Article For The American Physical Society Meeting On Shock Compression Of Condensed Matter, Hawaii, June, 200

Propagation of highly nonlinear signals in a two dimensional network of granular chains

We report the first experimental observation of highly nonlinear signals propagating in a two dimensional system composed of granular chains. In this system one of the chains contacts two others to allow splitting and redirecting the solitary-like signal formed in the first chain. The system consists of a double Y-shaped guide in which high- and low-modulus chains of spheres are arranged in various geometries. We observed fast splitting of the initial pulse, rapid chaotization of the signal and sharp bending of the propagating acoustic information. Pulse and energy trapping was also observed in composite systems assembled from hard- and soft-particles in the branches

Predicting C-H/π\pi interactions with nonlocal density functional theory

We examine the performance of a recently developed nonlocal density functional in predicting a model noncovalent interaction, the weak bond between an aromatic $\pi$ system and an aliphatic C-H group. The new functional is a significant improvement over traditional density functionals, providing results which compare favorably to high-level quantum-chemistry techniques but at considerably lower computational cost. Interaction energies in several model C-H/$\pi$ systems are in generally good agreement with coupled-cluster calculations, though equilibrium distances are consistently overpredicted when using the revPBE functional for exchange. The new functional correctly predicts changes in energy upon addition of halogen substituents.Comment: 5 pages, 4 figure

ECONOMICALLY OPTIMAL WILDFIRE INTERVENTION REGIMES

Wildfires in the United States result in total damages and costs that are likely to exceed billions of dollars annually. Land managers and policy makers propose higher rates of prescribed burning and other kinds of vegetation management to reduce amounts of wildfire and the risks of catastrophic losses. A wildfire public welfare maximization function, using a wildfire production function estimated using a time series model of a panel of Florida counties, is employed to simulate the publicly optimal level of prescribed burning in an example county in Florida (Volusia). Evaluation of the production function reveals that prescribed fire is not associated with reduced catastrophic wildfire risks in Volusia County Florida, indicating a short-run elasticity of -0.16 and a long-run elasticity of wildfire with respect to prescribed fire of -0.07. Stochastic dominance is used to evaluate the optimal amount of prescribed fire most likely to maximize a measure of public welfare. Results of that analysis reveal that the optimal amount of annual prescribed fire is about 3 percent (9,000 acres/year) of the total forest area, which is very close to the actual average amount of prescribed burning (12,700 acres/year) between 1994-99.Resource /Energy Economics and Policy,

Segmentation of RT3D Ultrasound with Implicit Deformable Models Without Gradients

This paper presents the implementation and validation of a new 3D deformable model method, based on the Mumford-Shah functional for segmentation of three-dimensional real-time ultrasound. An experiment on 10 patients with primary hypertension was carried out to compare three segmentation methods for quantification of right and left ventricular ejection fraction: (1) manual tracing by an expert cardiologist, (2) 2D parametric deformable model, and (3) 3D implicit deformable model implemented with a level set framework. Deformable model segmentations were performed on denoised data using a (3D+Time) brushlet expansion. The clinical study showed superior performance of the deformable model in assessing ejection fraction when compared to MRI measures. It also showed that the three-dimensional deformable model improved EF measures, which is explained by a more accurate segmentation of small and convoluted ventricular shapes when integrating the third spatial dimension

LV Volume Quantification via Spatiotemporal Analysis of Real-Time 3-D Echocardiography

This paper presents a method of four-dimensional (4-D) (3-D+Time) space-frequency analysis for directional denoising and enhancement of real-time three-dimensional (RT3D) ultrasound and quantitative measures in diagnostic cardiac ultrasound. Expansion of echocardiographic volumes is performed with complex exponential wavelet-like basis functions called brushlets. These functions offer good localization in time and frequency and decompose a signal into distinct patterns of oriented harmonics, which are invariant to intensity and contrast range. Deformable-model segmentation is carried out on denoised data after thresholding of transform coefficients. This process attenuates speckle noise while preserving cardiac structure location. The superiority of 4-D over 3-D analysis for decorrelating additive white noise and multiplicative speckle noise on a 4-D phantom volume expanding in time is demonstrated. Quantitative validation, computed for contours and volumes, is performed on in vitro balloon phantoms. Clinical applications of this spatiotemporal analysis tool are reported for six patient cases providing measures of left ventricular volumes and ejection fraction

Psychometric properties of standardized balance confidence, fear of falling, and falls-efficacy measures in people with lower limb amputations

Background: In Canada, \u3e50% of community-dwelling lower limb amputees (LLA) fall at least once each year, a rate that is almost twice that of community-dwelling older adults. While the physical consequences of falls may be readily apparent, psychological sequelae that follow may be just as, if not more, detrimental than an actual fall itself. Current measures of balance confidence show no change in LLA following discharge from rehabilitation. The limited detectable change may be due to content validity challenges of the measures as they were not developed for the unique challenges faced by LLA. Objectives: 1) Review items from standardized scales measuring falls-related concerns with participants to determine the applicability of test items to the LLA population. 2) Solicit novel examples of relevant activities from participants to inform the development of an LLA-specific balance confidence scale. Proposed Methods: This cross-sectional study will include adult unilateral/bilateral LLA (n=60) recruited through the Outpatient Amputee Rehabilitation Program at Parkwood Institute. Falls-related concerns will be evaluated using seven relevant clinical measures of a concern for falling. Participants will be asked to identify inapplicable questions and to provide i) a list of activities they are physically able to do but are avoiding; and ii) a list of activities they currently do but are worried about becoming unsteady or falling when performed. Future Directions/Implications: The results of this project could provide important details for the creation of an amputee-specific measurement tool to better quantify psychological concerns related to falls

Understanding Parkinson’s Through Visual Narratives: “I’m Not Mrs. Parkinson’s”

Although it is accepted that individuals with Parkinson’s disease (PD) must navigate challenges such as receiving their diagnosis, and changing daily occupations, little is known about how they navigate. The purpose of this study is to deepen the current understanding of the experience of living with PD and its implications for occupation through a narrative visual methodology (photo-elicitation). Methods: Six individuals with PD were asked to take photographs and share verbal narrative accounts to illustrate their experience of living with PD. Findings: Results highlight the interrelationship between occupation and identity, as many of the participants stories were interpreted as foregrounding the negotiation of occupation, and how such negotiation shaped their sense of identity. Overall three major themes were identified: (1) Framing the meaning of PD (accepting the disease as part of who they were); (2) Negotiating engagement in occupation (ongoing deliberation whether to continue engaging in certain aspects of life as PD progressed); and (3) Being ready to accept changes that impact personal or social identity (Readiness to accept help and to identify as someone with PD). Conclusion: Attending to insights regarding the lived experience of PD will enhance quality of care through informing an enriched client-centered, occupation-based approach

Lv volume quantification via spatiotemporal analysis of real-time 3-d echocardiography

Abstract—This paper presents a method of four-dimensional (4-D) (3-D + Time) space–frequency analysis for directional denoising and enhancement of real-time three-dimensional (RT3D) ultrasound and quantitative measures in diagnostic cardiac ultrasound. Expansion of echocardiographic volumes is performed with complex exponential wavelet-like basis functions called brushlets. These functions offer good localization in time and frequency and decompose a signal into distinct patterns of oriented harmonics, which are invariant to intensity and contrast range. Deformable-model segmentation is carried out on denoised data after thresholding of transform coefficients. This process attenuates speckle noise while preserving cardiac structure location. The superiority of 4-D over 3-D analysis for decorrelating additive white noise and multiplicative speckle noise on a 4-D phantom volume expanding in time is demonstrated. Quantitative validation, computed for contours and volumes, is performed on in vitro balloon phantoms. Clinical applications of this spaciotemporal analysis tool are reported for six patient cases providing measures of left ventricular volumes and ejection fraction. Index Terms—Echocardiography, LV volume, spaciotemporal analysis, speckle denoising. I