Carotid atherosclerotic plaque characterisation by measurement of ultrasound sound speed in vitro at high frequency, 20 MHz

PhDThe first part of the study was to characterise the acoustic properties of an IEC agar-based tissue mimicking material (TMM) at ultrasound frequencies centred around 20 MHz. The TMM acoustic properties measured were the amplitude attenuation coefficient (dB cm-1MHz-1), the sound speed (ms-1) and the backscattered power spectral density characteristics of spectral slope (dB MHz-1), y-axis intercept (dB) and reflected power (dB). The acoustic properties were measured over a temperature range of 22 - 37oC. Both the attenuation coefficient and sound speed, both group and phase, showed good agreement with the expected values of 0.5 dB cm-1 MHz-1 and 1540 ms-1 respectively with average values of 0.49 dB cm-1MHz-1 (st.dev. ± 0.03) and 1541.9 ms-1 (st.dev. ± 8.5). Overall, this non-commercial agar-based TMM was shown to perform as expected at the higher frequency range of 17-23 MHz and was seen to retain its acoustic properties of attenuation and speed of sound over a three year period. For the second part of the study, composite sound speed was measured in carotid plaque embedded in TMM. The IEC TMM was adapted to a clear agar gel. The contour maps from the attenuation plots were used to match the composite sound speed data to the photographic mask of plaque outline and thus the histological data. By solution of sets of simultaneous equations using a matrix inversion, the individual speed values for five plaque components were derived; TMM, elastin, fibrous/collagen, calcification and lipid. The results for derived sound speed in the adapted TMM were consistently close to the expected value of soft tissue, 1540 ms-1. The fibrous tissue showed a mean value of 1584 ms-1 at body temperature, 37oC. The derived sound speeds for elastic and lipid exhibited large inter-quartile ranges. The calcification had a significantly higher sound speed than the other plaque components at 1760 - 2000 ms-1

The History Of Election Day In Philadelphia: A Study In American Political Ritual

The dissertation is a history of Election Day practices, and the public discourse about Election Day, in the city of Philadelphia, from the early 1700s to the present time. The questions animating the work are two-fold. First, a historical question: how and why did Election Day disappear as a public celebration in Philadelphia’s civic calendar? Second, a theoretical question: what general statements can we make about the message that the performance of an Election Day sends to a population like the voting public of Philadelphia? The answer to the first question is that the disappearance of Election Day’s more spectacular, obvious, and public features— especially those that emphasized bodily communication—was part of a more general shift in American public culture. This was shift away from populist, vulgar forms of publicity toward a more personalized, sedate, and textualized style. The answer to the second question is that Election Day, like many other forms of ritual, is a mode of communication that addresses particularly the tensions and paradoxes within a society—whether these be tensions between classes of people or between worldviews. Because Election Day is a public illustration of the democratic paradox, it provides an important forum in which the public can reflect upon and struggle with central questions within the culture. Its disappearance as public holiday thus marks a significant loss for democratic life

A Borrowed Childhood Memory, New York City, 1923

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EVALUATION OF A WOBBLING MASS MODEL SIMULATING FEMALE IMPACT LANDINGS

Females involved in sport are more susceptible to injury during landing than their male counterparts, which may partially be attributed to their ability to attenuate the excessive loads experienced. This investigation aimed to evaluate a customised simulation model developed to replicate the kinetics of female impact landings. The model incorporated a rigid foot and shank, thigh and upper body segments, which each comprised wobbling and rigid masses. Model accuracy was defined by quantifying the differences between simulated and actual landings. The model reproduced ground reaction force profiles to 16% of the measured range and peak vertical force times to 8ms. The limitations of using a rigid foot were addressed and future applications of the model for gaining insight into load attenuation strategies used by females in landing were discussed

THE INFLUENCE OF MASS PROPORTIONS AND COUPLING STIFFNESS ON LOADING IN SIMULATED FOREFOOT-HEEL LANDINGS

The aim of this study was to gain a further insight into whole body mass proportion and coupling stiffness contributions to loading in forefoot-heel landings. Two landing performances were simulated using a customised wobbling mass model. Personalised segmental mass proportions and coupling stiffness values were independently and simultaneously modified in the model and the impact loads examined. A 10% larger rigid mass proportion increased the peak GFz and ankle moment by 0.73 BW and 0.38 N·m.kg-1, respectively. Reducing mass coupling stiffness had a smaller influence on loading than mass proportion and alleviated the larger peak GFz produced with relatively larger rigid mass proportions. A neuromuscular response that is tuned to an individual’s inherent mass properties may help to alleviate the excessive loads incurred in landing

EVALUATION OF PLANAR RECONSTRUCTION ACCURACY FOR TWO TECHNIQUES INCORPORATING CAMERA TILT

Planar analyses of sporting activities routinely employ scaling techniques with the camera elevated above the activity. An alternative technique for planar reconstruction can be derived from the DLT. This study compared reconstruction accuracy for scaling with 2D-DLT for a large field of view as camera tilt increased. Four calibration and 30 reconstruction markers on a vertical plane were recorded at tilt angles from 0° to 6°. Locations for the reconstruction markers were estimated using both techniques and compared to their known values. The smallest reconstruction errors were obtained using 2D- DLT and were unaffected by lilt angle (

A PILOT STUDY OF THE KNEE JOINT ACTION CONTRIBUTIONS TO LOADING IN LANDINGS PERFORMED BY FEMALES

Females are particularly susceptible to knee injuries in landing. This investigation aimed to gain further insight into the contributions of female knee joint actions to loading in landing. A wobbling mass model was used to simulate landings executed with a self-selected strategy. The selected knee actions were modified and the resulting loads were examined. A 0.05 s change in knee joint action timing substantially increased the peak vertical ground reaction force (GFz) by 1.55 BW. Conversely, a small reduction in peak GFz (0.06 BW) was produced using a 10 % more extended knee during the impact. The prominent influence the knee joint action timing had on loading may be attributed to the need to maintain coordinated and continuous load attenuation. Subject-specific modifications to landing strategies were found to achieve load reductions

Optimised performance of the backward longswing on rings

Many elite gymnasts perform the straight arm backward longswing on rings in competition. Since points are deducted if gymnasts possess motion on completion of the movement, the ability to successfully perform the longswing to a stationary final handstand is of great importance. Sprigings et al. (1998) found that for a longswing initiated from a still handstand the optimum performance of an inelastic planar simulation model resulted in a residual swing of more than 3° in the final handstand. For the present study, a three-dimensional simulation model of a gymnast swinging on rings, incorporating lateral arm movements used by gymnasts and mandatory apparatus elasticity, was used to investigate the possibility of performing a backward longswing initiated and completed in handstands with minimal swing. Root mean square differences between the actual and simulated performances for the orientations of the gymnast and rings cables, the combined cable tension and the extension of the gymnast were 3.2°, 1.0°, 270 N and 0.05 m respectively. The optimised simulated performance initiated from a handstand with 2.1° of swing and using realistic changes to the gymnast's technique resulted in 0.6° of residual swing in the final handstand. The sensitivity of the backward longswing to perturbations in the technique used for the optimised performance was determined. For a final handstand with minimal residual swing (2°) the changes in body configuration must be timed to within 15 m s while a delay of 30 m s will result in considerable residual swing (7°)

The memory and identity theory of ICD-11 complex posttraumatic stress disorder

The 11th version of the International Classification of Diseases (ICD-11) includes complex posttraumatic stress disorder (CPTSD) as a separate diagnostic entity alongside posttraumatic stress disorder (PTSD). ICD-11 CPTSD is defined by six sets of symptoms, three that are shared with PTSD (reexperiencing in the here and now, avoidance, and sense of current threat) and three (affective dysregulation, negative self-concept, and disturbances in relationships) representing pervasive "disturbances in self-organization" (DSO). There is considerable evidence supporting the construct validity of ICD-11 CPTSD, but no theoretical account of its development has thus far been presented. A theory is needed to explain several phenomena that are especially relevant to ICD-11 CPTSD such as the role played by prolonged and repeated trauma exposure, the functional independence between PTSD and DSO symptoms, and diagnostic heterogeneity following trauma exposure. The memory and identity theory of ICD-11 CPTSD states that single and multiple trauma exposure occur in a context of individual vulnerability which interact to give rise to intrusive, sensation-based traumatic memories and negative identities which, together, produce the PTSD and DSO symptoms that define ICD-11 CPTSD. The model emphasizes that the two major and related causal processes of intrusive memories and negative identities exist on a continuum from prereflective experience to full self-awareness. Theoretically derived implications for the assessment and treatment of ICD-11 CPTSD are discussed, as well as areas for future research and model testing. (PsycInfo Database Record (c) 2023 APA, all rights reserved)