Background/Objective: InFLUenza Patient-reported Outcome (FLU-PRO Plus) is a 34-item patient-repo... more Background/Objective: InFLUenza Patient-reported Outcome (FLU-PRO Plus) is a 34-item patient-reported outcome instrument designed to capture the intensity and frequency of viral respiratory symptoms. This study evaluates whether FLU-PRO Plus responses could discriminate between symptoms of coronavirus disease 2019 (COVID-19) and influenza-like illness (ILI) with no COVID diagnosis, as well as forecast disease progression. Methods: FLU-PRO Plus was administered daily for 14 days. Exploratory factor analysis was used to reduce the FLU-PRO Plus responses on the first day to 3 factors interpreted as "symptom clusters." The 3 clusters were used to predict COVID-19 versus ILI diagnosis in logistic regression. Correlation between the clusters and quality of life (QoL) measures was used to assess concurrent validity. The timing of self-reported return to usual health in the 14-day period was estimated as a function of the clusters within COVID-19 and ILI groups. Results: Three hundred fourteen patients completed day 1 FLU-PRO Plus, of which 65% had a COVID-19 diagnosis. Exploratory factor analysis identified 3 symptom clusters: (1)general Body, (2) tracheal/bronchial, and (3) nasopharyngeal. Higher nasopharyngeal scores were associated with higher odds of COVID-19 compared with ILI diagnosis [adjusted odds ratio = 1.61 (1.21, 2.12)]. Higher tracheal/bronchial scores were associated with lower odds of COVID-19 [0.58 (0.44, 0.77)]. The 3 symptom clusters were correlated with multiple QoL measures (r = 0.14-0.56). Higher scores on the general body and tracheal/bronchial symptom clusters were associated with prolonged time to return to usual health [adjusted hazard ratios: 0.76 (0.64, 0.91), 0.80 (0.67, 0.96)]. Conclusion: Three symptom clusters identified from FLU-PRO Plus responses successfully discriminated patients with COVID-19 from non-COVID ILI and were associated with QoL and predicted symptom duration.
Declaration of originality: I declare that the work presented in this thesis is my own and other ... more Declaration of originality: I declare that the work presented in this thesis is my own and other published works have been referenced appropriately. The copyright of this thesis rests with the author. Unless otherwise indicated, its contents are licensed under a Creative Commons Attribution-Non Commercial 4.0 International Licence (CC BY-NC). Under this licence, you may copy and redistribute the material in any medium or format. You may also create and distribute modified versions of the work. This is on the condition that: you credit the author and do not use it, or any derivative works, for a commercial purpose. When reusing or sharing this work, ensure you make the licence terms clear to others by naming the licence and linking to the licence text. Where a work has been adapted, you should indicate that the work has been changed and describe those changes. Please seek permission from the copyright holder for uses of this work that are not included in this licence or permitted under UK Copyright Law.
The U.S. Coast Guard identified the problem of passenger vessels becoming overloaded due to incre... more The U.S. Coast Guard identified the problem of passenger vessels becoming overloaded due to increased passenger weight. Our project goal was to recommend an effective method that would allow vessel masters to know if their vessel has exceeded its maximum allowable weight. Through background research and interviews with people in the industry, we established twelve possible solutions to the problem. We recommended four solutions to help avoid passenger vessel overloading
Modelling and Simulation in Materials Science and Engineering, 2021
Quantum-mechanical (QM) simulations, thanks to their predictive power, can provide significant in... more Quantum-mechanical (QM) simulations, thanks to their predictive power, can provide significant insights into the nature and dynamics of defects such as vacancies, dislocations and grain boundaries. These considerations are essential in the context of the development of reliable, inexpensive and environmentally friendly alloys. However, despite significant progress in computer performance, QM simulations of defects are still extremely time-consuming with ab-initio/non-parametric methods. The two-centre Slater–Koster (SK) tight-binding (TB) models can achieve significant computational efficiency and provide an interpretable picture of the electronic structure. In some cases, this makes TB a compelling alternative to models based on abstraction of the electronic structure, such as the embedded atom model. The biggest challenge in the implementation of the SK method is the estimation of the optimal and transferable parameters that are used to construct the Hamiltonian matrix. In this pa...
International Journal of Chronic Obstructive Pulmonary Disease, 2021
Introduction: Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are important... more Introduction: Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are important events that may precipitate other adverse outcomes. Accurate AECOPD event identification in electronic administrative data is essential for improving population health surveillance and practice management. Objective: Develop codified algorithms to identify moderate and severe AECOPD in two US healthcare systems using administrative data and electronic medical records, and validate their performance by calculating positive predictive value (PPV) and negative predictive value (NPV). Methods: Data from two large regional integrated health systems were used. Eligible patients were identified using International Classification of Diseases (Ninth Edition) COPD diagnosis codes. Two algorithms were developed: one to identify potential moderate AECOPD by selecting outpatient/emergency visits associated with AECOPD-related codes and antibiotic/systemic steroid prescriptions; the other to identify potential severe AECOPD by selecting inpatient visits associated with corresponding codes. Algorithms were validated via patient chart review, adjudicated by a pulmonologist. To estimate PPV, 300 potential moderate AECOPD and 250 potential severe AECOPD events underwent review. To estimate NPV, 200 patients without any AECOPD identified by the algorithms (100 patients each without moderate or severe AECOPD) during the two years following the index date underwent review to identify AECOPD missed by the algorithm (false negatives). Results: The PPVs (95% confidence interval [CI]) for both moderate and severe AECOPD were high: 293/298 (98.3% [96.1-99.5]) and 216/225 (96.0% [92.5-98.2]), respectively. NPV was lower for moderate AECOPD (75.0% [65.3-83.1]) than for severe AECOPD (95.0% [88.7-98.4]). Results were consistent across both healthcare systems. Conclusion: This study developed healthcare utilization-based algorithms to identify moderate and severe AECOPD in two separate healthcare systems. PPV for both algorithms was high; NPV was lower for the moderate algorithm. Replication and consistency of results across two healthcare systems support the external validity of these findings.
Proceedings of Panoramic Radio Astronomy: Wide-field 1-2 GHz research on galaxy evolution — PoS(PRA2009), 2010
Spectroscopy of redshifted radio absorption of atomic and molecular species provide excellent pro... more Spectroscopy of redshifted radio absorption of atomic and molecular species provide excellent probes of the cold component of the gas in the early Universe which can be used to address many important issues, such as measuring baryonic content, probing large-scale structure and galaxy evolution, as well as obtaining independent measurements of various combinations of fundamental constants at large look-back times. However, such systems are currently very rare with only 80 detected in H I 21-cm and five in OH and millimetre-band species. Here we summarise the main selection criteria responsible for this and how the next generation of radio telescopes are expected to circumvent these through their wide instantaneous bandwidths and fields-of-view. Specifically: * Speaker.
Proceedings of the International Astronomical Union, 2012
Cool neutral gas provides the raw material for all star formation in the Universe, and yet, from ... more Cool neutral gas provides the raw material for all star formation in the Universe, and yet, from a survey of the hosts of high redshift radio galaxies and quasars, we find a complete dearth of atomic (H i 21-cm) and molecular (OH, CO, HCO + & HCN) absorption at redshifts z > ∼ 3 (Curran et al. 2008). Upon a thorough analysis of the optical photometry, we find that all of our targets have ionising (λ 912Å) ultraviolet continuum luminosities of LUV 10 23 W Hz −1. We therefore attribute this deficit to the traditional optical selection of targets biasing surveys towards the most ultraviolet luminous objects, where the intense radiation excites the neutral gas to the point where it cannot engage in star formation (Curran & Whiting 2010). However, this hypothesis does not explain why there is a critical luminosity, rather than a continuum where the detections gradually become fewer and fewer as the harshness of the radiation increases. We show that by placing a quasar within a galaxy of gas there is always a finite ultraviolet luminosity above which all of the gas is ionised. This demonstrates that these galaxies are probably devoid of star-forming material rather than this being at abundances below the sensitivity limits of current radio telescopes.
Monthly Notices of the Royal Astronomical Society, 2015
We report the discovery of a new 21-cm H I absorption system using commissioning data from the Bo... more We report the discovery of a new 21-cm H I absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5-1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between z = 0.4 and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at z = 0.44 towards the GHz-peaked spectrum radio source PKS B1740−517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for H I absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the H I gas is intrinsic to the host galaxy of the radio source. The narrow [O III] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMM-Newton satellite exhibit an absorbed X-ray spectrum that is
Publications of the Astronomical Society of Australia, 2000
We present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quas... more We present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quasars, forming an unbiassed sub-sample of the Parkes Flat-Spectrum Sample. Data are also presented for 12 optically selected QSOs, drawn from the Large Bright QSO Survey. The spectral energy distributions of the radio- and optically-selected sources are quite different. The optically selected QSOs are all very similar: they have blue spectral energy distributions curving downwards at shorter wavelengths. Roughly 90% of the radio-selected quasars have roughly power-law spectral energy distributions, with slopes ranging fromFv∝v0toFv∝v−2. The remaining 10% have spectral energy distributions showing sharp peaks: these are radio galaxies and highly reddened quasars. Four radio sources were not detected down to magnitude limits ofH∼ 19·6. These are probably high redshift (z> 3) galaxies or quasars. We show that the colours of our red quasars lie close to the stellar locus in the optical: the...
Monthly Notices of the Royal Astronomical Society: Letters, 2011
We report the detection of the third H I 21-cm absorber in the sight-line towards the z = 2.64 qu... more We report the detection of the third H I 21-cm absorber in the sight-line towards the z = 2.64 quasar MG J0414+0534 (4C +05.19). In addition to the absorption at the host redshift and in the z = 0.96 gravitational lens, we find, through a decimetre-wave spectral scan towards this source, strong absorption at z = 0.38. We believe this may be associated with 'Object X', an additional feature apparent in the field of the lensing galaxy and lensed images, on the basis of its close proximity to the quasar images and the possible detection of the [O III] doublet in a published optical spectrum. If real, the strength of the [O III] emission would suggest the presence of an active galactic nucleus, or a gas-rich galaxy undergoing rapid star formation, either of which is consistent with the strong outflows apparent in the 21-cm spectrum. Although this is the strongest intervening 21-cm absorber found to date (a column density of N H I 10 22 cm −2 , for a modest T s /f 300 K), simultaneous observations failed to detect any of the 18-cm OH lines at the 21-cm redshift. This suggests that, as for the lensing galaxy, this is not the primary location of the intervening material responsible for the very red colour of MG J0414+0534.
Monthly Notices of the Royal Astronomical Society: Letters, 2007
We report the detection of H I 21-cm absorption in the z = 0.96 early-type lensing galaxy towards... more We report the detection of H I 21-cm absorption in the z = 0.96 early-type lensing galaxy towards MG J0414+0534 with the Green Bank Telescope. The absorption, with total N HI = 1.6 (T s /f) × 10 18 cm −2 , is resolved into two strong components, probably due to the two strongest lens components, which are separated by 0.4 ′′. Unlike the other three lenses which have been detected in H I, J0414+0534 does not exhibit strong OH absorption, giving a OH/H I column density ratio of N OH /N HI < ∼ 10 −6 (for T s = 100 K, T x = 10 K and f HI = f OH = 1). This underabundance of molecular gas may indicate that the extreme optical-near-IR colour (V − K = 10.26) along the line-of-sight is not due to the lens. We therefore suggest that despite the strong upper limits on molecular absorption at the quasar redshift, as traced by millimetre lines, the extinction occurs primarily in the quasar host galaxy.
Monthly Notices of the Royal Astronomical Society, 2011
From a survey for the redshifted H I 21-cm and OH 18-cm absorption in the hosts of a sample of ra... more From a survey for the redshifted H I 21-cm and OH 18-cm absorption in the hosts of a sample of radio galaxies and quasars, we detect H I in three of the 10 and OH in none of the 14 sources for which useful data were obtained. As expected from our recent result, all of the 21-cm detections occur in sources with ultraviolet (UV) continuum luminosities of L UV ≤ 10 23 W Hz −1. At these 'moderate' luminosities, we also obtain four non-detections, although, as confirmed by the equipartition of detections between the type 1 and type 2 objects, this near-50 per cent detection rate cannot be attributed to unified schemes of active galactic nuclei (AGNs). All of our detections are at redshifts of z 0.67, which, in conjunction with our faint source selection, biases against UV luminous objects. The importance of the UV luminosity (over AGN type) in the detection of the 21-cm absorption is further supported by the nondetections in the two high-redshift (z ∼ 3.6-3.8) radio galaxies, which are both type 2 objects, while having L UV > 10 23 W Hz −1. Our 21-cm detections in combination with those previously published give a total of eight (associated and intervening) H I-absorbing sources searched and undetected in OH. Using the detected 21-cm line strengths to normalize the limits, we find that only two of these eight sources may have been searched sufficiently deeply in OH, even though these are marginal.
Monthly Notices of the Royal Astronomical Society, 2008
We present the results of a z ≥ 2.9 survey for H I 21-cm and molecular absorption in the hosts of... more We present the results of a z ≥ 2.9 survey for H I 21-cm and molecular absorption in the hosts of radio quasars using the Giant Metrewave Radio Telescope and the Tidbinbilla 70-m telescope. Although the atomic gas has been searched to limits capable of detecting most known absorption systems, no H I was detected in any of the 10 sources. Previously published searches, which are overwhelmingly at redshifts of z 1, exhibit a 42 per cent detection rate (31 out of 73 sources), whereas the inclusion of our survey yields a 17 per cent detection rate (two out of 12 sources) at z > 2.5. We therefore believe that our high-redshift selection is responsible for our exclusive non-detections, and find that at ultraviolet (UV) luminosities of L UV 10 23 W Hz −1 , 21-cm absorption has never been detected. We also find this to not only apply to our targets, but also those at low redshift exhibiting similar luminosities, giving zero detections out of a total of 16 sources over z = 0.24 to 3.8. This is in contrast to the L UV 10 23 W Hz −1 sources where there is a near 50 per cent detection rate of 21-cm absorption. The mix of 21-cm detections and non-detections is currently attributed to orientation effects, where according to unified schemes of active galactic nuclei, 21-cm absorption is more likely to occur in sources designated as radio galaxies (type 2 objects, where the nucleus is viewed through dense obscuring circumnuclear gas) than in quasars (type 1 objects, where we have a direct view to the nucleus). However, due to the exclusively high UV luminosities of our targets it is not clear whether orientation effects alone can wholly account for the distribution, although there exists the possibility that the large luminosities are indicative of a changing demographic of galaxy types. We also find that below luminosities of L UV ∼ 10 23 W Hz −1 , both type 1 and type 2 objects have a 50 per cent likelihood of exhibiting 21-cm absorption. Finally, we do not detect molecular gas in any of the sources. The lack of H I absorption, combined with the results from Paper I, suggests these sources are not conducive to high molecular abundances.
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Papers by Thomas Whiting