1,233 research outputs found

    Characterization of Consolidated Granular Salt

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    Granular salt is likely to be used as backfill material and a seal system component within geologic salt formations serving as a repository for long-term isolation of nuclear waste. Pressure from closure of the surrounding salt formation will promote consolidation of granular salt, eventually resulting in properties comparable to native salt. Understanding the consolidation processes dependence on stress state, moisture availability, and temperature is important for demonstrating sealing functions and long-term repository performance. This study includes the characterization of laboratory-consolidated salt by means of microstructural observations, measurement of physical properties related to the pore structure, and quantification of pore sizes areas under differing conditions. Samples for this study were obtained from mine-run granular salt from the Waste Isolation Pilot Plant (WIPP) and Avery Island which were consolidated hydrostatically with varying conditions of stress up to 38 MPa, temperatures up to 250C, and moisture additions of 1%. Porosities achieved from consolidation ranged between 0.01 and 0.22. Microstructural observations using optical and scanning electron (SEM) microscopes were made to provide direct insight into deformation mechanisms during consolidation. Porosity, specific surface area, permeability, and tortuosity factor were quantified through multiple techniques including point counting, petrographic image analysis (PIA), porosimetry, and steady-state gas permeametry. Pore area distributions categorized into micropores (\u3c1000 m2) and macropores (\u3e1000 m2) were developed from Back-Scattered Electrons (BSE) SEM images analyzed in Fiji. Overall, the addition of moisture produces a higher degree of cohesion among grains, lower permeabilities and porosities as well as higher specific surface areas and lower macropore frequency at higher temperatures. A higher stress was also seen to lower porosity, increase specific surface area, and lower the frequency of micropores. Higher temperature samples experienced low porosities, more grain boundary cohesion, and, in WIPP samples, a higher frequency of macropores in the range from 1000 to 2500 m2. From microstructural observations, samples with 1% added moisture or those which were unvented during consolidation demonstrated clear pressure solution processes with tightly cohered grain boundaries and areas of occluded fluid pore spaces. Samples consolidated without additional moisture exhibited mainly cataclastic and plastic deformation. Recrystallization was also observed in samples consolidated at temperatures of 90C with added moisture and 250C. Porosities obtained from methods that measured both total and connected porosity were similar, suggesting a connected pore network within samples. From image analysis, a general trend of increase in specific surface area with a decrease in porosity was observed. Permeability values decreased with decreasing porosity and are comparable to permeability-porosity relationships for rock salt published by others. The tortuosity factor was calculated from the Carman-Kozeny model, which incorporates permeability, porosity, and specific surface area, and generally increased with decreasing porosity. Pore area analysis reveals porosities consisting predominately of macropores and minor changes in pore area frequencies with respect to consolidation conditions. It is well known that stress, temperature, and moisture affect the behavior of salt consolidation, but complete studies on deformation mechanisms and the evolving pore structure over a large range of conditions is not abundant. Information provided here enhances the current understanding of granular salt consolidation by offering direct insight into micro-mechanic processes and transformation of pore structure components

    A Study of Robert Schumann and his Impact on the German Song Cycle

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    The purpose of this research was to gain information about Robert Schumann and his impact on the German song cycle. The specific problems of the study were as follows: 1.) To trace the origins and development of the song cycle; 2.) To identify the significance of Robert Schumann to the German song cycle; and 3.) To analyze Frauenliebe und-Leben (‘A Woman’s Life and Love’), a song cycle composed by Schumann in 1840, in terms of form, style, and vocal technique. This research investigates the return of Robert Schumann from instrumental music back to vocal music and how he helped develop the German song cycle genre

    CHANGES IN LUMBAR JOINT MOMENTS USING A FEMALE SPECIFIC TORSO AND DYNAMIC BREAST MODEL DURING RUNNING

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    This study aimed to investigate the effect of breast mass and motion on lumbar flexor / extensor moments during running. Kinematic and kinetic data were collected for a female participant running at 2.6 m/s. An MRI scan was used to calculate breast mass and centre of mass location. An OpenSim model was customised with two point-mass segments added to the torso to represent the breasts. Three model variations were constructed (combined breast and torso mass; separate breast and torso mass without breast motion; separate breast and torso mass with breast motion). Findings show that neglecting breast motion causes peak lumbar extensor moments to be underestimated by ~3.4%, compared with a combined breast and torso mass model. These results highlight the importance of including breast motion in female specific MSK models, during activities such as running

    CHANGES IN LUMBAR JOINT MOMENTS USING A FEMALE SPECIFIC TORSO MODEL DURING RUNNING

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    The purpose of this study was to quantify the peak lumbar joint flexor / extensor moments following changes in torso and breast mass during running using an innovative computer musculoskeletal model. Kinematic and kinetic data were collected for a female participant running at 2.6 m/s. An MRI scan of the breasts was used to calculate breast mass and centre of mass location relative to the torso. An OpenSim whole body model was customised with two point-mass segments added to the torso to represent the breasts. Key findings have shown that changes in breast mass can cause peak lumbar flexor / extensors moments to be over or underestimated by up to ~18%. These results suggest that including the mass of the breasts in female specific models, during dynamic activities such as running, is an important aspect that must be considered for future work

    A METHOD FOR CALCULATING DYNAMIC BREAST CENTRE OF MASS DURING RUNNING

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    This study aimed to develop a novel method for calculating breast centre of mass (COM) during running for use in musculoskeletal modelling. Magnetic resonance imaging (MRI) scans and kinematic data were collected from a female participant running at 2.6 m·s-1. A breast surface marker array was used to calculate the COM of 16 segments, based upon tissue composition from the MRI scan. The motion of the surface markers were used to calculate breast COM position during running. Breast COM was more superior, medial and posterior than the nipple marker. Breast COM range of motion was lower (~50%) in all directions during running when compared to the nipple marker. Results suggest that the localised breast deformation is the key factor in calculating breast COM during running

    Longitudinal analysis of the developing rhesus monkey brain using magnetic resonance imaging: birth to adulthood.

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    We have longitudinally assessed normative brain growth patterns in naturalistically reared Macaca mulatta monkeys. Postnatal to early adulthood brain development in two cohorts of rhesus monkeys was analyzed using magnetic resonance imaging. Cohort A consisted of 24 rhesus monkeys (12 male, 12 female) and cohort B of 21 monkeys (11 male, 10 female). All subjects were scanned at 1, 4, 8, 13, 26, 39, and 52 weeks; cohort A had additional scans at 156 weeks (3 years) and 260 weeks (5 years). Age-specific segmentation templates were developed for automated volumetric analyses of the T1-weighted magnetic resonance imaging scans. Trajectories of total brain size as well as cerebral and subcortical subdivisions were evaluated over this period. Total brain volume was about 64 % of adult estimates in the 1-week-old monkey. Brain volume of the male subjects was always, on average, larger than the female subjects. While brain volume generally increased between any two imaging time points, there was a transient plateau of brain growth between 26 and 39 weeks in both cohorts of monkeys. The trajectory of enlargement differed across cortical regions with the occipital cortex demonstrating the most idiosyncratic pattern of maturation and the frontal and temporal lobes showing the greatest and most protracted growth. A variety of allometric measurements were also acquired and body weight gain was most closely associated with the rate of brain growth. These findings provide a valuable baseline for the effects of fetal and early postnatal manipulations on the pattern of abnormal brain growth related to neurodevelopmental disorders

    Stepfamily Relationship Quality and Children’s Internalizing and Externalizing Problems

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    The stepfamily literature is replete with between-group analyses by which youth residing in stepfamilies are compared to youth in other family structures across indicators of adjustment and well-being. Few longitudinal studies examine variation in stepfamily functioning to identify factors that promote the positive adjustment of stepchildren over time. Using a longitudinal sample of 191 stepchildren (56% female, mean age = 11.3 years), the current study examines the association between the relationship quality of three central stepfamily dyads (stepparent–child, parent–child, and stepcouple) and children's internalizing and externalizing problems concurrently and over time. Results from path analyses indicate that higher levels of parent–child affective quality are associated with lower levels of children's concurrent internalizing and externalizing problems at Wave 1. Higher levels of stepparent–child affective quality are associated with decreases in children's internalizing and externalizing problems at Wave 2 (6 months beyond baseline), even after controlling for children's internalizing and externalizing problems at Wave 1 and other covariates. The stepcouple relationship was not directly linked to youth outcomes. Our findings provide implications for future research and practice

    Dog Welfare, Well-Being and Behavior: Considerations for Selection, Evaluation and Suitability for Animal-Assisted Therapy

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    Health care and human service providers may include dogs in formal intervention settings to positively impact human physical, cognitive and psychosocial domains. Dogs working within this context are asked to cope with a multitude of variables including settings, populations, activities, and schedules. In this article, the authors highlight how both the preparation and operation of dogs within animal-assisted therapy (AAT) differs from less structured animal-assisted activities (AAA) and more exclusive assistance animal work; the authors highlight the gaps in our knowledge in this regard, and propose an ethically sound framework for pragmatic solutions. This framework also emphasizes the need for good dog welfare to safeguard all participants. If dogs are not properly matched to a job or handler, they may be subjected to unnecessary stress, anxiety, and miscommunication that can lead to disinterest in the work, overt problematic behavioral or health outcomes, or general unsuitability. Such issues can have catastrophic outcomes for the AAT. The authors propose standards for best practices for selection, humane-based preparation and training, and ongoing evaluation to ensure the health, welfare and well-being of dogs working in AAT, which will have concomitant benefits for clients and the professionalism of the field
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