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Search Results: 1 - 10 of 6169 matches for " Ian Woolley "
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Trends in detectable viral load by calendar year in the Australian HIV observational database
Law Matthew G,Woolley Ian,Templeton David J,Roth Norm
Journal of the International AIDS Society , 2011, DOI: 10.1186/1758-2652-14-10
Abstract: Background Recent papers have suggested that expanded combination antiretroviral treatment (cART) through lower viral load may be a strategy to reduce HIV transmission at a population level. We assessed calendar trends in detectable viral load in patients recruited to the Australian HIV Observational Database who were receiving cART. Methods Patients were included in analyses if they had started cART (defined as three or more antiretrovirals) and had at least one viral load assessment after 1 January 1997. We analyzed detectable viral load (>400 copies/ml) in the first and second six months of each calendar year while receiving cART. Repeated measures logistic regression methods were used to account for within and between patient variability. Rates of detectable viral load were predicted allowing for patients lost to follow up. Results Analyses were based on 2439 patients and 31,339 viral load assessments between 1 January 1997 and 31 March 2009. Observed detectable viral load in patients receiving cART declined to 5.3% in the first half of 2009. Predicted detectable viral load based on multivariate models, allowing for patient loss to follow up, also declined over time, but at higher levels, to 13.8% in 2009. Conclusions Predicted detectable viral load in Australian HIV Observational Database patients receiving cART declined over calendar time, albeit at higher levels than observed. However, over this period, HIV diagnoses and estimated HIV incidence increased in Australia.
Preparation of Pure Gaussian States via Cascaded Quantum Systems
Shan Ma,Matthew J. Woolley,Ian R. Petersen,Naoki Yamamoto
Mathematics , 2014,
Abstract: This paper provides an alternative approach to the problem of preparing pure Gaussian states in a linear quantum system. It is shown that any pure Gaussian state can be generated by a cascade of one-dimensional open quantum harmonic oscillators, without any direct interaction Hamiltonians between these oscillators. This is physically advantageous from an experimental point of view. An example on the preparation of two-mode squeezed states is given to illustrate the theory.
Linear quantum systems with diagonal passive Hamiltonian and a single dissipative channel
Shan Ma,Ian R. Petersen,Matthew J. Woolley
Mathematics , 2015,
Abstract: Given any covariance matrix corresponding to a so-called pure Gaussian state, a linear quantum system can be designed to achieve the assigned covariance matrix. In most cases, however, one might obtain a system that is difficult to realize in practice. In this paper, we restrict our attention to a special class of linear quantum systems, i.e., systems with diagonal passive Hamiltonian and a single dissipative channel. The practical implementation of such a system would be relatively simple. We then parametrize the class of pure Gaussian state covariance matrices that can be achieved by this particular type of linear quantum system.
Quantum filtering for multiple diffusive and Poissonian measurements
Muhammad F. Emzir,Matthew J. Woolley,Ian R. Petersen
Mathematics , 2015, DOI: 10.1088/1751-8113/48/38/385302
Abstract: We provide a rigorous derivation of a quantum filter for the case of multiple measurements being made on a quantum system. We consider a class of measurement processes which are functions of bosonic field operators, including combinations of diffusive and Poissonian processes. This covers the standard cases from quantum optics, where homodyne detection may be described as a diffusive process and photon counting may be described as a Poissonian process. We obtain a necessary and sufficient condition for any pair of such measurements taken at different output channels to satisfy a commutation relationship. Then, we derive a general, multiple measurement quantum filter as an extension of a single-measurement quantum filter. As an application we explicitly obtain the quantum filter corresponding to homodyne detection and photon counting at the output ports of a beam splitter, correcting an earlier result.
An Investigation of the Effect of the Swamping Phenomenon on Several Block Procedures for Multiple Outliers in Univariate Samples  [PDF]
Thomas W. Woolley
Open Journal of Statistics (OJS) , 2013, DOI: 10.4236/ojs.2013.35035

In its broadest sense, this paper reviews the general outlier problem, the means available for addressing the discordancy (or lack thereof) of an outlier (or outliers), and possible strategies for dealing with them. Two alternate approaches to the multiple outlier problem, consecutive and block testing, and their respective inherent weaknesses, masking and swamping, are discussed. In addition, the relative susceptibility of several tests for outliers in normal samples to the swamping phenomena is reported.

The Significance of HIV ‘Blips’ in Resource-Limited Settings: Is It the Same? Analysis of the Treat Asia HIV Observational Database (TAHOD) and the Australian HIV Observational Database (AHOD)
Rupa Kanapathipillai, Hamish McManus, Adeeba Kamarulzaman, Poh Lian Lim, David J. Templeton, Matthew Law, Ian Woolley
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086122
Abstract: Introduction Magnitude and frequency of HIV viral load blips in resource-limited settings, has not previously been assessed. This study was undertaken in a cohort from a high income country (Australia) known as AHOD (Australian HIV Observational Database) and another cohort from a mixture of Asian countries of varying national income per capita, TAHOD (TREAT Asia HIV Observational Database). Methods Blips were defined as detectable VL (≥ 50 copies/mL) preceded and followed by undetectable VL (<50 copies/mL). Virological failure (VF) was defined as two consecutive VL ≥50 copies/ml. Cox proportional hazard models of time to first VF after entry, were developed. Results 5040 patients (AHOD n = 2597 and TAHOD n = 2521) were included; 910 (18%) of patients experienced blips. 744 (21%) and 166 (11%) of high- and middle/low-income participants, respectively, experienced blips ever. 711 (14%) experienced blips prior to virological failure. 559 (16%) and 152 (10%) of high- and middle/low-income participants, respectively, experienced blips prior to virological failure. VL testing occurred at a median frequency of 175 and 91 days in middle/low- and high-income sites, respectively. Longer time to VF occurred in middle/low income sites, compared with high-income sites (adjusted hazards ratio (AHR) 0.41; p<0.001), adjusted for year of first cART, Hepatitis C co-infection, cART regimen, and prior blips. Prior blips were not a significant predictor of VF in univariate analysis (AHR 0.97, p = 0.82). Differing magnitudes of blips were not significant in univariate analyses as predictors of virological failure (p = 0.360 for blip 50–≤1000, p = 0.309 for blip 50–≤400 and p = 0.300 for blip 50–≤200). 209 of 866 (24%) patients were switched to an alternate regimen in the setting of a blip. Conclusion Despite a lower proportion of blips occurring in low/middle-income settings, no significant difference was found between settings. Nonetheless, a substantial number of participants were switched to alternative regimens in the setting of blips.
Revista de Economía Institucional , 2010,
Abstract: the essay offers a new understanding of how financial markets work. the key departure from conventional theory is to recognize that investors do not invest directly in securities but through agents such as fund managers. agents have better information and different objectives than their customers (principals) and this asymmetry is shown as the source of inefficiency: mispricing, bubbles and crashes. a separate outcome is that agents are in a position to capture for themselves the bulk of the returns from financial innovations. principal/agent problems do a good job of explaining how the global finance sector has become so bloated, profitable and prone to crisis. remedial action involves the principals changing the way they contract with, and instruct agents. the essay ends with a manifesto of policies that pension funds and other large investors can adopt to mitigate the destructive features of delegation both for their individual benefit and to promote social welfare in the form of a leaner, more efficient and more stable finance sector.
Por qué los mercados financieros son tan ineficientes y explotadores, y una propuesta de solución
Paul Woolley
Revista de Economía Institucional , 2010,
Abstract: Este ensayo presenta una nueva manera de entender el funcionamiento de los mercados financieros. Su diferencia clave con la teoría convencional es que reconoce que los inversionistas no invierten directamente en valores sino a través de agentes tales como los administradores de fondos. Los agentes tienen objetivos diferentes y mejor información que sus clientes, y esta asimetría es fuente de ineficiencia: mala fijación de precios, burbujas y colapsos de Bolsa. Un resultado independiente es que los agentes pueden capturar la masa de ganancias de las innovaciones financieras. Los problemas de principal-agente ayudan a explicar por qué el sector financiero global se ha vuelto tan hipertrofiado, rentable y propenso a crisis. La acción remedial consiste en que los principales modifiquen la manera de contratar o instruir a los agentes. El ensayo termina con un manifiesto de políticas que los fondos de pensiones y otros grandes inversionistas pueden adoptar para atenuar los efectos destructivos de la delegación sobre sus beneficios individuales, y promover el bienestar social en forma de un sector financiero más esbelto, eficiente y estable.
Splenectomy Associated Changes in IgM Memory B Cells in an Adult Spleen Registry Cohort
Paul U. Cameron,Penelope Jones,Malgorzata Gorniak,Kate Dunster,Eldho Paul,Sharon Lewin,Ian Woolley,Denis Spelman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0023164
Abstract: Asplenic patients have a lifelong risk of overwhelming post-splenectomy infection and have been reported to have low numbers of peripheral blood IgM memory B cells. The clinical value of quantitation of memory B cells as an indicator of splenic abnormality or risk of infection has been unclear. To assess changes in B cell sub-populations after splenectomy we studied patients recruited to a spleen registry (n = 591). A subset of 209 adult asplenic or hyposplenic subjects, and normal controls (n = 140) were tested for IgM memory B cells. We also determined a) changes in IgM memory B cells with time after splenectomy using the cross-sectional data from patients on the registry and b) the kinetics of changes in haematological markers associated with splenectomy(n = 45). Total B cells in splenectomy patients did not differ from controls, but memory B cells, IgM memory B cells and switched B cells were significantly (p<0.001) reduced. The reduction was similar for different indications for splenectomy. Changes of asplenia in routine blood films including presence of Howell-Jolly bodies (HJB), occurred early (median 25 days) and splenectomy associated thrombocytosis and lymphocytosis peaked by 50 days. There was a more gradual decrease in IgM memory B cells reaching a stable level within 6 months after splenectomy. IgM memory B cells as proportion of B cells was the best discriminator between splenectomized patients and normal controls and at the optimal cut-off of 4.53, showed a true positive rate of 95% and false positive rate of 20%. In a survey of 152 registry patients stratified by IgM memory B cells around this cut-off there was no association with minor infections and no registry patients experienced OPSI during the study. Despite significant changes after splenectomy, conventional measures of IgM memory cells have limited clinical utility in this population.
The Potential Energy Surface in Molecular Quantum Mechanics
Brian Sutcliffe,R. Guy Woolley
Physics , 2013,
Abstract: The idea of a Potential Energy Surface (PES) forms the basis of almost all accounts of the mechanisms of chemical reactions, and much of theoretical molecular spectroscopy. It is assumed that, in principle, the PES can be calculated by means of clamped-nuclei electronic structure calculations based upon the Schr\"{o}dinger Coulomb Hamiltonian. This article is devoted to a discussion of the origin of the idea, its development in the context of the Old Quantum Theory, and its present status in the quantum mechanics of molecules. It is argued that its present status must be regarded as uncertain.
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