Doctor of Philosophy

dissertationGranular diamond composites are particulate reinforced composites, where the particulate phase is a grade of high-hardness polycrystalline diamond, embedded in a tougher, hard-material matrix. Granular diamond composites are hierarchically-structured materials. In addition to the macrostructure and microstructure, granular diamond composites have a mesostructure that encompasses the morphology of the matrix and granules and is characterized by parameters such as component volume fraction, granular sphericity, and matrix uniformity. The mesostructure is functionally designed to improve the performance of the composite in petroleum well-drilling applications by increasing the fracture resistance while maintaining the wear resistance. The impact of the mesostructure on the flexural strength, wear resistance, impact resistance, and in-field performance was measured. Physical testing showed that volume fraction of the tougher, matrix phase can be increased significantly before the wear resistance of the composite decreases appreciably. But the testing also showed that the method developed to produce the composites resulted in component materials with inferior properties. The flexural strength of a polycrystalline-diamond/tungsten-carbide material system was explored using several modeling techniques, including analytic, two-dimensional numeric, and three-dimensional numeric models. Residual stresses, arising from the change in conditions after the material is formed in a high-temperature, high-pressure sintering process, have a significant impact on the calculated strength of the composite. Dilatational residual stresses have never been treated in a rigorous manner in the literature and are often neglected completely. In this study, the thermal and dilatational residual stresses were modeled. Stresses from externally applied loads preferentially concentrate in the stiffer diamond phase. Thermal residual stresses strengthen the stiffer and weaker diamond phase through residual compression and weaken the carbide phase through residual tension. The dilatational residual stresses partially counteract the thermal residual stresses. Without thermal residual stresses the composite would have lower strength due to premature failure in the diamond phase. Without dilatational residual stresses the composite would have lower strength due to premature failure in the carbide phase. The strengths predicted by the enhanced models match the measured strengths quite well, despite significant uncertainty in the material properties and process parameters

In Vitro Bacterial Contamination of Amniotic Fluid: Effects on Fluorescence Polarization Lung Maturity Testing

Objective: We sought to determine the effect of bacteria on fluorescence polarization (FPOL) testing of amniotic fluid

The 2011 Eco3D Flight Campaign: Vegetation Structure and Biomass Estimation from Simultaneous SAR, Lidar and Radiometer Measurements

The Eco3D campaign was conducted in the Summer of 2011. As part of the campaign three unique and innovative NASA Goddard Space Flight Center airborne sensors were flown simultaneously: The Digital Beamforming Synthetic Aperture Radar (DBSAR), the Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) and the Cloud Absorption Radiometer (CAR). The campaign covered sites from Quebec to Southern Florida and thereby acquired data over forests ranging from Boreal to tropical wetlands. This paper describes the instruments and sites covered and presents the first images resulting from the campaign

Efficacy of group exercise–based cancer rehabilitation delivered via telehealth (TeleCaRe) : protocol for a randomized controlled trial

Background: Access to rehabilitation to support cancer survivors to exercise is poor. Group exercise–based rehabilitation may be delivered remotely, but no trials have currently evaluated their efficacy. Objective: We aimed to evaluate the efficacy of a group exercise–based cancer rehabilitation program delivered via telehealth compared to usual care for improving the quality of life of cancer survivors. Methods: A parallel, assessor-blinded, pragmatic randomized controlled trial with embedded cost and qualitative analysis will be completed. In total, 116 cancer survivors will be recruited from a metropolitan health network in Melbourne, Victoria, Australia. The experimental group will attend an 8-week, twice-weekly, 60-minute exercise group session supervised via videoconferencing supplemented by a web-based home exercise program and information portal. The comparison group will receive usual care including standardized exercise advice and written information. Assessments will be completed at weeks 0 (baseline), 9 (post intervention), and 26 (follow-up). The primary outcome will be health-related quality of life measured using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire at week 9. Secondary measures include walking capacity (6-minute walk test), physical activity (activPAL accelerometer), self-efficacy (Health Action Process Approach Questionnaire), and adverse events. Health service data including hospital length of stay, hospital readmissions, and emergency department presentations will be recorded. Semistructured interviews will be completed within an interpretive description framework to explore the patient experience. The primary outcome will be analyzed using linear mixed effects models. A cost-effectiveness analysis will also be performed. Results: The trial commenced in April 2022. As of June 2022, we enrolled 14 participants. Conclusions: This trial will inform the future implementation of cancer rehabilitation by providing important data about efficacy, safety, cost, and patient experience. Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN12621001417875; https://tinyurl.com/yc5crwtr International Registered Report Identifier (IRRID): PRR1-10.2196/3855

Impact of deploying multiple point-of-care tests with a 'sample first' approach on a sexual health clinical care pathway. A service evaluation.

OBJECTIVES: To assess clinical service value of STI point-of-care test (POCT) use in a 'sample first' clinical pathway (patients providing samples on arrival at clinic, before clinician consultation). Specific outcomes were: patient acceptability; whether a rapid nucleic acid amplification test (NAAT) for Chlamydia trachomatis/Neisseria gonorrhoeae (CT/NG) could be used as a POCT in practice; feasibility of non-NAAT POCT implementation for Trichomonas vaginalis (TV) and bacterial vaginosis (BV); impact on patient diagnosis and treatment. METHODS: Service evaluation in a south London sexual health clinic. Symptomatic female and male patients and sexual contacts of CT/NG-positive individuals provided samples for diagnostic testing on clinic arrival, prior to clinical consultation. Tests included routine culture and microscopy; CT/NG (GeneXpert) NAAT; non-NAAT POCTs for TV and BV. RESULTS: All 70 (35 males, 35 females) patients approached participated. The 'sample first' pathway was acceptable, with >90% reporting they were happy to give samples on arrival and receive results in the same visit. Non-NAAT POCT results were available for all patients prior to leaving clinic; rapid CT/NG results were available for only 21.4% (15/70; 5 males, 10 females) of patients prior to leaving clinic. Known negative CT/NG results led to two females avoiding presumptive treatment, and one male receiving treatment directed at possible Mycoplasma genitalium infection causing non-gonococcal urethritis. Non-NAAT POCTs detected more positives than routine microscopy (TV 3 vs 2; BV 24 vs 7), resulting in more patients receiving treatment. CONCLUSIONS: A 'sample first' clinical pathway to enable multiple POCT use was acceptable to patients and feasible in a busy sexual health clinic, but rapid CT/NG processing time was too long to enable POCT use. There is need for further development to improve test processing times to enable POC use of rapid NAATs

Microscale thermophoresis quantifies biomolecular interactions under previously challenging conditions

Item does not contain fulltextMicroscale thermophoresis (MST) allows for quantitative analysis of protein interactions in free solution and with low sample consumption. The technique is based on thermophoresis, the directed motion of molecules in temperature gradients. Thermophoresis is highly sensitive to all types of binding-induced changes of molecular properties, be it in size, charge, hydration shell or conformation. In an all-optical approach, an infrared laser is used for local heating, and molecule mobility in the temperature gradient is analyzed via fluorescence. In standard MST one binding partner is fluorescently labeled. However, MST can also be performed label-free by exploiting intrinsic protein UV-fluorescence. Despite the high molecular weight ratio, the interaction of small molecules and peptides with proteins is readily accessible by MST. Furthermore, MST assays are highly adaptable to fit to the diverse requirements of different biomolecules, such as membrane proteins to be stabilized in solution. The type of buffer and additives can be chosen freely. Measuring is even possible in complex bioliquids like cell lysate allowing close to in vivo conditions without sample purification. Binding modes that are quantifiable via MST include dimerization, cooperativity and competition. Thus, its flexibility in assay design qualifies MST for analysis of biomolecular interactions in complex experimental settings, which we herein demonstrate by addressing typically challenging types of binding events from various fields of life science

SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems

Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS DR8 (which occurred in Jan 2011). This paper presents an overview of the four SDSS-III surveys. BOSS will measure redshifts of 1.5 million massive galaxies and Lya forest spectra of 150,000 quasars, using the BAO feature of large scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z<0.7 and at z~2.5. SEGUE-2, which is now completed, measured medium-resolution (R=1800) optical spectra of 118,000 stars in a variety of target categories, probing chemical evolution, stellar kinematics and substructure, and the mass profile of the dark matter halo from the solar neighborhood to distances of 100 kpc. APOGEE will obtain high-resolution (R~30,000), high signal-to-noise (S/N>100 per resolution element), H-band (1.51-1.70 micron) spectra of 10^5 evolved, late-type stars, measuring separate abundances for ~15 elements per star and creating the first high-precision spectroscopic survey of all Galactic stellar populations (bulge, bar, disks, halo) with a uniform set of stellar tracers and spectral diagnostics. MARVELS will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10-40 m/s, ~24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. (Abridged)Comment: Revised to version published in The Astronomical Journa