The thermal Sunyaev-Zel'dovich effect as a probe of cluster physics and cosmology.

Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.The universe is a complex environment playing host to a plethora of macroscopic and microscopic processes. Understanding the interplay and evolution of such processes will help to shed light on the properties and evolution of the universe. The juxtaposition is that in order to study small scale effects one needs to observe large scale structure as the latter objects trace the history of our universe. Galaxy groups and clusters are the largest known objects in the universe and thus provide a means to probe the evolution of structure formation in the universe as well as the underlying cosmology. In this thesis we investigate how clusters observed through the Sunyaev-Zel’dovich (SZ) effect can be used to constrain cosmological models. In addition, we present the first results of the Atacama Cosmology Telescope (ACT), a mm-wave telescope measuring the small-scale microwave background anisotropy, and conclude with preliminary SZ cluster detection performed on the latest ACT sky maps. In the first part of this thesis we investigate the ability of high resolution cosmic microwave background (CMB) experiments to detect hot gas in the outer regions of nearby group halos. We construct two hot gas models for the halos; a simpler adiabatic formalism with the gas described by a polytropic equation of state, and a more general gas description which incorporates feedback effects in line with constraints from X-ray observations. We calculate the thermal Sunyaev- Zel’dovich (tSZ) signal in these halos and compare it to the sensitivities of upcoming and current tSZ survey experiments such as ACT, PLANCK and the South Pole Telescope (SPT). Through the application of a multi-frequency Wiener filter, we derive mass and redshift based tSZ detectability limits for the various experiments, incorporating effects of galactic and extragalactic foregrounds as well as the CMB. In this study we find that galaxy group halos with virial masses below 1014M. can be detected at z ~< 0.05 with the mass limit dropping to 3 − 4 × 1013M. at z ~< 0.01. Probing such halos with the tSZ effect allows one to map the hot gas in the outer regions, providing a means to constrain gas processes, such as feedback, as well as the distribution of baryons in the local universe. In the fourth chapter, we extend this analysis and determine the ability of ACT to constrain galactic feedback and star formation in clusters and groups using the tSZ effect. We present a new microwave deblender, which provides a means of extracting accurate halo fluxes and radial profiles from maps of the tSZ effect. Considering various surveys that could be performed by ACT, we use multi-frequency filtering on simulated sky maps to predict how well such surveys will constrain gas properties using a Fisher matrix analysis. We find that the current ACT survey will be unable to constrain any gas parameters. However, if ACT were to survey a smaller area then we will be able to constrain feedback. Furthermore, with greater sensitivity, we will be able to place interesting constraints on the gas feedback, and baryon and stellar fractions. The fifth chapter in this thesis concerns itself with the first results of the Atacama Cosmology Telescope Project. In this section we discuss the map-making method as well as telescope beam characterisation, an understanding of which is important in any subsequent map analyses. In addition, we present maps of eight clusters observed at 148 GHz via the SZ effect, and provide flux and signal to noise estimates of the clusters. In the final chapter we present a preliminary analysis of the latest 148 GHz ACT maps from the 2008 observing season. We study the sky maps using single frequency wiener filtering, allowing for CMB, dust and correlated noise contamination. To substantiate our results, we compare the number counts, recovered fluxes and sample purity from simulated sky maps. The compounding effects of CMB and correlated noise result in high contamination levels below a signal to noise ratio of 6, however our investigation shows that above 8¾ our cluster sample is ¼ 80% pure. A cluster list containing 44 detections, of which 8 are previously known, is also presented, along with a Table listing the candidate cluster positions and fluxes. The candidate cluster catalogue will be used for follow-up studies using optical and X-ray observations.Correct mathematical forms are found in the electronic version of the thesis

Hepatic transcriptomic profiles from barramundi, Lates calcarifer, as a means of assessing organism health and identifying stressors in rivers in northern Queensland

Resource managers need to differentiate between sites with and without contaminants and those where contaminants cause impacts. Potentially, transcriptomes could be used to evaluate sites where contaminant-induced effects may occur, to identify causative stressors of effects and potential adverse outcomes. To test this hypothesis, the hepatic transcriptomes in Barramundi, a perciforme teleost fish, (Lates calcarifer) from two reference sites, two agriculturally impacted sites sampled during the dry season, and an impacted site sampled during the wet season were compared. The hepatic transcriptome was profiled using RNA-Seq. Multivariate analysis showed that transcriptomes were clustered based on site and by inference water quality, but not sampling time. The largest differences in transcriptomic profile were between reference sites and a site sampled during high run-off, showing that impacted sites can be identified via RNA-Seq. Transcripts with altered abundance were linked to xenobiotic metabolism, peroxisome proliferation and stress responses, indicating putative stressors with the potential for adverse outcomes in barramundi

Age-related changes in three-dimensional foot motion during barefoot walking in children aged between 7 and 11 years old

Background: The biomechanical complexity of children’s feet changes throughout childhood, yet kinematic development of the feet is poorly understood. Further work exploring the kinematic profile of children’s feet would be beneficial to help inform our understanding of the typical development of children’s feet. Research Question: Do three-dimensional segmental kinematics of the feet during gait relate to age in a sample of children age 7–11 years? Methods: This study was a secondary analysis of an existing database representing one hundred and twenty-one children age 7 – 11 years (90 male, 31 female; mean ± SD: age 9.57 ± , 1.17 years, height 1.37 ± 0.08 m, body mass 35.61 ± 9.33 kg). Fifteen, 9 mm retroreflective markers were attached to the right shank and foot of each participant in, line with the 3DFoot model. Multi-segmental joint kinematics were collected during barefoot walking. Sagittal, frontal, and transverse planar motion was described for the shank-calcaneus, calcaneus-midfoot, and midfoot-metatarsals segment of the right foot. Principal component analysis (PCA) was used to reduce the major modes of variation in the data to fully explore foot segment motion over the entire gait cycle. Correlations and multiple regression between PCA outputs with age, and potential confounding factors are presented. Results: Significant positive correlations were found between age and greater calcaneus, dorsiflexion, midfoot inversion and adduction, and metatarsal dorsiflexion, plantarflexion and abduction. There were no significant confounding effects of height, body mass, walking speed or gender on the relationships between age and PCA outputs. Significance: The findings from this study demonstrated a relationship between foot kinematics and age suggesting that the development of foot kinematics is ongoing until at least the age of 11 years. This work offers a comprehensive data set of inter-segmental kinematics which helps to advance understanding of the development of the pediatric foot

Influence of team rating on running performance in elite Gaelic football

It is currently unknown how team rating influences running performance in Gaelic football. Global positioning system technologies were used to quantify match-running performance within 5 elite Gaelic football teams over a period of 5 years (2012-2016). In total 780 player data sets were collected over 95 matches. Running performance variables included total distance, high-speed distance (≥17 km·h), and the percentage of high-speed distance. Team ratings were determined objectively using the Elo rating system for Gaelic football. Reference team rating had trivial effects on total distance (p = 0.011, partial η = 0.008) and high-speed distance (p = 0.011, partial η = 0.008). Opposition team rating had small effects on total distance (p = 0.005, partial η = 0.016) and high-speed distance (p = 0.001, partial η = 0.020). Top-tier teams cover greater total distances and high-speed distance than lower tier teams. Players cover considerably less total distance and high-speed distance against tier-3 and tier-4 teams. Tier-1 players ran a significantly higher percentage of distance at high speed than players who played for tier-2 teams (p = 0.020). The competitive advantage of top-tier Gaelic football teams is closely linked with their ability to demonstrate a higher physical intensity than lower tier teams

The influence of match outcome on running performance in elite Gaelic football

Introduction: Match outcome has been linked to running performance in many sports; however, the association has not yet been examined in Gaelic football. Methods: GPS technologies (4-Hz, VX Sport, Lower Hutt, New Zealand) were used with 5 elite Gaelic football teams over a period of 5 years (2012–2016), amounting to 95 matches. In total, 780 full match data sets were collected. Game movements were divided into total distance and high-speed distance (≥17 km h−1). Match outcomes were divided into big losses (≥6 points), small losses (≤5points), draws, small wins (≤5 points) and big wins (≥6 points). Results: Team (P ≤ 0.001), playing position (P ≤ 0.001) and match outcome (P ≤ 0.034) had a significant effect on total and high-speed distance. In the first (P = 0.008) and second (P = 0.002) quarters of games players ran significantly less high-speed distance in big losses in comparison to draws. In the fourth quarter, players ran significantly less high-speed distance in big losses than in draws (P = 0.001), small wins (P = 0.044) and big wins (P = 0.011). Conclusion: The current study confirms that running performance is a contributing factor to match outcome in Gaelic football. Coaches should be aware how contextual factors can influence running performance

Transcriptomic, lipid, and histological profiles suggest changes in health in fish from a pesticide hot spot.

Barramundi (Lates calcarifer) were collected at the beginning (1st sampling) and end (2nd sampling) of the wet season from Sandy Creek, an agriculturally impacted catchment in the Mackay Whitsundays region of the Great Barrier Reef catchment area, and from Repulse Creek, located approximately 100 km north in Conway National Park, to assess the impacts of pesticide exposure. Gill and liver histology, lipid class composition in muscle, and the hepatic transcriptome were examined. The first sample of Repulse Creek fish showed little tissue damage and low transcript levels of xenobiotic metabolism enzymes. Sandy Creek fish showed altered transcriptomic patterns, including those that regulate lipid metabolism, xenobiotic metabolism, and immune response; gross histological alterations including lipidosis; and differences in some lipid classes. The second sampling of Repulse Creek fish showed similar alterations in hepatic transcriptome and tissue structure as fish from Sandy Creek. These changes may indicate a decrease in health of pesticide exposed fish

Concurrent Validity of Lower Limb Muscle Strength by Handheld Dynamometry in Children 7 to 11 Years Old

Context: The assessment of pediatric muscle strength is necessary in a range of applications, including rehabilitation programs. Handheld dynamometry (HHD) is considered easy to use, portable, and low cost, but validity to measure lower limb muscle strength in children has not been assessed. Objective: To determine the concurrent validity of lower limb torque from HHD compared with isokinetic dynamometry (ID) in children aged from 7 to 11 years old. Design: A descriptive assessment of concurrent validity of lower limb joint torques from HHD compared with ID. Methods: Sixty-one typically developing children underwent assessment of maximal hip, knee, and ankle isometric torque by HHD and ID using standardized protocols. Joint positions were selected to represent maximal strength and were replicated between devices. Concurrent validity was determined by Pearson correlation, limits of agreement, and Bland–Altman plots. Results: Correlations between HHD and ID were moderate to large for knee extension (r 95% CI, .39 to .73), small to large for plantar flexion (r 95% CI, .29 to .67), knee flexion (r 95% CI, .16 to .59), hip flexion (r 95% CI, .21 to .57), hip extension (r 95% CI, .18 to .54), and hip adduction (r 95% CI, .12 to .56), and small to moderate for dorsiflexion (r 95% CI, −.11 to .39) and hip abduction (r 95% CI, −.02 to .46). Limits of agreement for all joint torques were greater than 10% indicating large error in HHD measured torque compared with ID. A positive proportional bias was detected for plantarflexion, indicating that HHD underestimated torque to a greater extent in participants with higher torque values. Conclusions: Maximal torque values from HHD and ID are consistent with those previously reported in the literature. Poor concurrent validity of HHD may have arisen from issues around joint position, joint stabilization, and the experience of the tester to prevent an isokinetic contraction. Pediatric lower limb muscle strength assessed by HHD should be interpreted with caution

Concurrent Validity of Lower Limb Muscle Strength by Handheld Dynamometry in Children 7 to 11 Years Old

Context The assessment of pediatric muscle strength is necessary in a range of applications, including rehabilitation programmes. Hand-held dynamometry is considered easy to use, portable and low cost, but validity to measure lower limb muscle strength in children has not been assessed. Objective To determine the concurrent validity of lower limb torque from hand-held dynamometry (HHD) compared to isokinetic dynamometry (ID) in children age 7 to 11 years old. Design A descriptive assessment of concurrent validity of lower limb joint torques from HHD compared to ID. Methods Sixty-one typically developing children underwent assessment of maximal hip, knee and ankle isometric torque by HHD and ID using standardized protocols. Joint positions were selected to represent maximal strength and were replicated between devices. Concurrent validity was determined by Pearson’s correlation, limits of agreement, and Bland-Altman plots. Results Correlations between HHD and ID were moderate-to-large for knee extension (r 95%CI: 0.39 to 0.73), small-to-large for plantarflexion (r 95%CI: 0.29 to 0.67), knee flexion (r 95%CI: 0.16 to 0.59), hip flexion (r 95%CI: 0.21 to 0.57), hip extension (r 95%CI: 0.18 to 0.54), and hip adduction (r 95%CI: 0.12 to 0.56), and small-to-moderate for dorsiflexion (r 95%CI: -0.11 to 0.39) and hip abduction (r 95%CI: -0.02 to 0.46). Limits of Agreement for all joint torques were greater than 10% indicating large error in HHD measured torque compared to ID. A positive proportional bias was detected for plantarflexion, indicating that HHD underestimated torque to a greater extent in participants with higher torque values. Conclusions Maximal torque values from HHD and ID are consistent with those previously reported in the literature. Poor concurrent validity of HHD may have arisen from issues around joint position, joint stabilization and the experience of the tester to prevent an isokinetic contraction. Pediatric lower limb muscle strength assessed by hand-held dynamometry should be interpreted with caution