Physical Sciences and Mathematics Commons^™

Person-Level And Household-Level Regression Estimation In Household Surveys, David G. Steel, Robert Graham Clark

Professor David Steel

A common class of survey designs involves selecting all people within selected households. Generalized regressionestimators can be calculated at either the person or household level. Implementing the estimator at the household level has the convenience of equal estimation weights for people within households. In this article the two approaches are compared theoretically and empirically for the case of simple random sampling of households and selection of all persons in each selected household. We find that the household level approach is theoretically more efficient in large samples and any empirical inefficiency in small samples is limited.

The 2003 Australian Breast Health Survey: Survey Design And Preliminary Results, Elmer V. Villanueva, Sandra C. Jones, Caroline Nehill, Simone K. Favelle, David G. Steel, Don Iverson, Helen Zorbas

Professor David Steel

The Breast Health Surveys, conducted by the National Breast Cancer Centre (NBCC) in 1996 and 2003, are designed to gain insight into the knowledge, attitudes and behaviours of a nationally representative sample of Australian women on issues relevant to breast cancer. In this article, we focus on major aspects of the design and present results on respondents' knowledge about mammographic screening. Methods: The 2003 BHS surveyed English-speaking Australian women aged 3069 without a history of breast cancer using computer-assisted telephone interviewing. Questions covered the following themes: knowledge and perceptions about incidence, mortality and risk; knowledge and behaviour regarding early detection, …

Contextual Effects In Modeling For Small Domain Estimation, Mohammad-Reza Namazi-Rad, David G. Steel

Professor David Steel

Many different Small Area Estimation (SAE) methods have been proposed to overcome the challenge of findingreliable estimates for small domains. Often, the required data for various research purposes are available at differentlevels of aggregation. Based on the available data, individual-level or aggregated-level models are used in SAE.However, parameter estimates obtained from individual and aggregated level analysis may be different, in practice.This may happen due to some substantial contextual or area-level effects in the covariates which may be misspecifiedin individual-level analysis. If small area models are going to be interpretable in practice, possible contextualeffects should be included. Ignoring these effects leads …

Estimates Of Probable Dementia Prevalence From Population-Based Surveys Compared With Dementia Prevalence Estimates Based On Meta-Analyses, Kaarin J. Anstey, Richard A. Burns, Carole Birrell, David G. Steel, Kim M. Kiely, Mary A. Luszcz

Professor David Steel

Background: National data on dementia prevalence are not always available, yet it may be possible to obtain estimates from large surveys that include dementia screening instruments. In Australia, many of the dementia prevalence estimates are based on European data collected between 15 and 50 years ago. We derived populationbased estimates of probable dementia and possible cognitive impairment in Australian studies using the Mini-Mental State Examination (MMSE), and compared these to estimates of dementia prevalence from meta-analyses of European studies.

Methods: Data sources included a pooled dataset of Australian longitudinal studies (DYNOPTA), and two Australian Bureau of Statistics National …

Investigation Of Relative Risk Estimates From Studies Of The Same Population With Contrasting Response Rates And Designs, Nicole M. Mealing, Emily Banks, Louisa R. Jorm, David G. Steel, Mark S. Clements, Kris D. Rogers

Professor David Steel

Background: There is little empirical evidence regarding the generalisability of relative risk estimates from studies which have relatively low response rates or are of limited representativeness. The aim of this study was to investigate variation in exposure-outcome relationships in studies of the same population with different response rates and designs by comparing estimates from the 45 and Up Study, a population-based cohort study (self-administered postal questionnaire, response rate 18%), and the New South Wales Population Health Survey (PHS) (computer-assisted telephone interview, response rate ~60%). Methods: Logistic regression analysis of questionnaire data from 45 and Up Study participants (n = 101,812) …

Fixed Rank Filtering For Spatio-Temporal Data, Noel Cressie, Tao Shi, Emily L. Kang

Professor Noel Cressie

Datasets from remote-sensing platforms and sensor networks are often spatial, temporal, and very large. Processing massive amounts of data to provide current estimates of the (hidden) state from current and past data is challenging, even for the Kalman filter. A large number of spatial locations observed through time can quickly lead to an overwhelmingly high-dimensional statistical model. Dimension reduction without sacrificing complexity is our goal in this article. We demonstrate how a Spatio-Temporal Random Effects (STRE) component of a statistical model reduces the problem to one of fixed dimension with a very fast statistical solution, a methodology we call Fixed …

Combining Outputs From The North American Regional Climate Change Assessment Program By Using A Bayesian Hierarchical Model, Emily L. Kang, Noel Cressie, Stephan R. Sain

Professor Noel Cressie

We investigate the 20-year-average boreal winter temperatures generated by an ensemble of six regional climate models (RCMs) in phase I of the North American Regional Climate Change Assessment Program. We use the long-run average (20-year integration) to smooth out variability and to capture the climate properties from the RCM outputs. We find that, although the RCMs capture the large-scale climate variation from coast to coast and from south to north similarly, their outputs can differ substantially in some regions. We propose a Bayesian hierarchical model to synthesize information from the ensemble of RCMs, and we construct a consensus climate signal …

Modeling Dynamic Controls On Ice Streams: A Bayesian Statistical Approach, L Mark Berliner, Kenneth Jezek, Noel Cressie, Yongku Kim, Calvin Lam, Cornelis Van Der Veen

Professor Noel Cressie

Our main goal is to exemplify the study of ice-stream dynamics via Bayesian statistical analysis incorporating physical, though imperfectly known, models using data that are both incomplete and noisy. The physical-statistical models we propose account for these uncertainties in a coherent, hierarchical manner. The initial modeling assumption estimates basal shear stress as equal to driving stress, but subsequently includes a random corrector process to account for model error. The resulting stochastic equation is incorporated into a simple model for surface velocities. Use of Bayes' theorem allows us to make inferences on all unknowns given basal elevation, surface elevation and surface …

A Method For Evaluating Bias In Global Measurements Of Co2 Total Columns From Space, D Wunch, P O. Wennberg, G C. Toon, B J. Connor, B Fisher, G B. Osterman, C Frankenberg, L Mandrake, C O'Dell, P Ahonen, S C. Biraud, R Castano, Noel Cressie, D Crisp, N M. Deutscher, A Eldering, M L. Fisher, David W. Griffith, M Gunson, P Heikkinen, G Keppel-Aleks, E Kyro, R Lindemaier, Ronald Macatangay, J Mendonca, J Messerschmidt, C E. Miller, I Morino, J Notholt, F A. Oyafuso, M Rettinger, J Robinson, C M. Roehl, R J. Salawitch, V Sherlock, K Strong, R Sussmann, T Tanaka, D R. Thompson, O Uchino, Thorsten Warneke, Steven C. Wofsy

Professor Noel Cressie

We describe a method of evaluating systematic errors in measurements of total column dry-air mole fractions of CO2 (XCO2) from space, and we illustrate the method by applying it to the v2.8 Atmospheric CO2 Observations from Space retrievals of the Greenhouse Gases Observing Satellite (ACOS-GOSAT) measurements over land. The approach exploits the lack of large gradients in XCO2 south of 25S to identify large-scale offsets and other biases in the ACOS-GOSAT data with several retrieval parameters and errors in instrument calibration. We demonstrate the effectiveness of the method by comparing the ACOS-GOSAT data in the Northern Hemisphere with ground truth …

Dynamical Random-Set Modeling Of Concentrated Precipitation In North America, Noel Cressie, Renato Assuncao, Scott H. Holan, Michael Levine, Orietta Nicolis, Jun Zhang, Jian Zou

Professor Noel Cressie

In order to study climate at scales where policy decisions can be made, regional climate models (RCMs) have been developed with much finer resolution (~50 km) than the ~500 km resolution of atmosphere-ocean general circulation models (AOGCMs). The North American Regional Climate Change Assessment Program (NARCCAP) is an international program that provides 50-km resolution climate output for the United States, Canada, and northern Mexico. In Phase I, there are six RCMs, from which we choose one to illustrate our methodology. The RCMs are updated every 3 hours and contain a number of variables, including temperature, precipitation, wind speed, wind direction, …

Rejoinder, Peter Craigmile, Catherine Caldert, Hongfei Li, Rajib Paul, Noel Cressie

Professor Noel Cressie

We agree with Schmidt that it is essential that researchers from many diverse areas have access to affordable, but still trustworthy, software. In this research project, substantial effort went into preparing datasets. Much of the data came from different government agencies, with databases arranged in multiple formats, often including variables that were not immediately relevant to our scientific pursuits. In our work on this project, the use of SAS was essential to producing clean datasets.

Hierarchical Model Building, Fitting, And Checking: A Behind-The-Scenes Look At A Bayesian Analysis Of Arsenic Exposure Pathways, Peter F. Craigmile, Catherine A. Calder, Hongfei Li, Rajib Paul, Noel Cressie

Professor Noel Cressie

In this article, we present a behind-the-scenes look at a Bayesian hierarchical analysis of pathways of exposure to arsenic (a toxic heavy metal) using the Phase I National Human Exposure Assessment Survey carried out in Arizona. Our analysis combines individual-level personal exposure measurements (biomarker and environmental media) with water, soil, and air observations from the ambient environment. We include details of our model-building exercise that involved a combination of exploratory data analysis and substantive knowledge in exposure science. Then we present our strategies for model fitting, which involved piecing together components of the hierarchical model in a systematic fashion to …

Accounting For Uncertainty In Ecological Analysis: The Strengths And Limitations Of Hierarchical Statistical Modeling, Noel Cressie, Catherine Calder, James Clark, Jay Ver Hoef, Christopher Wikle

Professor Noel Cressie

Analyses of ecological data should account for the uncertainty in the process(es) that generated the data. However, accounting for these uncertainties is a difficult task, since ecology is known for its complexity. Measurement and/or process errors are often the only sources of uncertainty modeled when addressing complex ecological problems, yet analyses should also account for uncertainty in sampling design, in model specification, in parameters governing the specified model, and in initial and boundary conditions. Only then can we be confident in the scientific inferences and forecasts made from an analysis. Probability and statistics provide a framework that accounts for multiple …

Spectral Density Estimation Through A Regularized Inverse Problem, Chunfeng Huang, Tailen Hsing, Noel Cressie

Professor Noel Cressie

In the study of stationary stochastic processes on the real line, the covariance function and the spectral density function are parameters of considerable interest. They are equivalent ways of expressing the temporal dependence in the process. In this article, we consider the spectral density function and propose a new estimator that is not based on the periodogram; the estimator is derived through a regularized inverse problem. A further feature of the estimator is that the data are not required to be observed on a grid. When the regularization condition is based on the function's first derivative, we give the estimator …

Air-Drying Of Banana: Influence Of Experimental Parameters, Slab Thickness, Banana Maturity And Harvesting Season, Minh-Hue Nguyen, William E. Price

William E. Price

Air-drying of banana slabs has been investigated and the influence of experimental parameters such as temperature, relative humidity and slab thickness has been studied. This was in part re-investigated because of inconsistencies in previous studies, particularly in relation to derived water diffusion coefficients. In addition, it is shown that harvest season and hence initial moisture content has a very marked influence on the drying kinetics. By contrast banana maturity (ripeness) has little influence on the kinetics despite there being significant differences in morphology and chemical composition between green and ripe bananas. The effect of these two variables on the drying …

Increased Probiotic Yogurt Or Resistant Starch Intake Does Not Affect Isoflavone Bioavailability In Subjects Consuming A High Soy Diet, Theresa A. Larkin, William E. Price, Lee B. Astheimer

William E. Price

Objective: Probiotics and prebiotics that affect gut microflora balance and its associated enzymeactivity may contribute to interindividual variation in isoflavone absorption after soy intake, possiblyenhancing isoflavone bioavailability. This study examined the effects of the consumption ofbioactive yogurt (a probiotic) or resistant starch (a known prebiotic) in combination with high soyintake on soy isoflavone bioavailability.Methods: Using a crossover design, chronic soy consumption was compared with soy plusprobiotic yogurt or resistant starch in older male and postmenopausal females (n 31). Isoflavonebioavailability was assessed at the beginning and end of each 5-wk dietary period by samplingplasma and urine after a standardized soy meal.Results: …

Fractionation Of Sedimentary Arsenic From Port Kembla Harbour, Nsw, Australia, Glennys A. O'Brien, William E. Price, Bryan E. Chenhall, Muhammad Damris

William E. Price

The binding of arsenic in sediments of the heavily industrialised Port Kembla Harbour, NSW, Australia, has been investigated. Both dredge and core samples have been used to develop a sieving/sequential extraction (SE) procedure. Dredge samples included oxic surficial and deeper anoxic sediment. The main core sample analysed was 18 cm deep, sliced at 2 cm intervals. Sediment was sieved to three size ranges (250 microm) and each of these was then subjected to a four step SE, sequentially solubilizing arsenic as ion exchangeable, 1 M HCl soluble, NH(2)OH.HCl soluble, and strong oxidising acid soluble. Concentrations of 50-500 mg As kg(-1) …

A Fragmentation Study Of Isoflavones In Negative Electrospray Ionization By Msn Ion Trap Mass Spectrometry And Triple Quadrupole Mass Spectrometry, Jinguo Kang, Larry A. Hick, William E. Price

William E. Price

This study has elucidated the fragmentation pathway for deprotonated isoflavones in electrospray ionization using MSn ion trap mass spectrometry and triple quadrupole mass spectrometry. Genistein-d4 and daidzein-d3 were used as references for the clarification of fragment structures. To confirm the relationship between precursor and product ions, some fragments were traced from MS2 to MS5. The previous literature for the structurally related flavones and flavanones located the loss of ketene (C2H2O) to ring C, whereas the present fragmentation study for isoflavones has shown that the loss of ketene occurs elsewhere at ring A. In the further fragmentation of the [M-H-CH3]•- radical …

Tissue Distribution Of Lignans In Rats In Response To Diet, Dose-Response, And Competition With Isoflavones, Timothy Murray, J. Kang, Lee Astheimer, William E. Price

William E. Price

This paper investigates the occurrence and distribution of the lignan metabolites enterodiol (END) and enterolactone (ENL) and the isoflavone daidzein (DAID) in rat tissues using liquid chromatography - electrospray ionisation mass spectrometry (LC – ESI/MSn) following a variety of dietary regimes. Further, we examined the dose-response and distribution of END and ENL in liver, testes, prostate and lung, and investigated the effects of competition between lignans and isoflavones on metabolite distribution. In liver, testes, prostate & lung tissue, dose related increases in END concentration were observed. In the testes, the co-administration of 60 mg/kg SDG with 60 mg/kg isoflavones produced …

Effect Of Organic Solvents On The Separation Of Benzoic Acids By Capillary Electrophoresis, Young J. Lee, William E. Price, Margaret Sheil

William E. Price

The effect of organic modifiers on the separation of a number of closely related isomeric benzoic acids by capillary electrophoresis is described. It is shown that while a single modifier concentration cannot help resolve the entire electropherogram, organic modifiers do significantly enhance the resolution of parts of the separation system by comparison with 40 mmol l-1 phosphate buffer. The effects on separation and retention times are discussed in terms of the effects on electroosmotic flow and the electrophoretic mobilities of the charged solutes. The effects were found to be modifier specific, although the trends were in the same direction (ie., …

Occurrence Of Phytoestrogens In Municipal Wastewater And Surface Waters, Jinguo Kang, William E. Price

William E. Price

Phytoestrogens (isoflavones, enterolignans and coumestrol) in wastewater samples and surface water samples have been analysed by LC-ESI-MSn. In wastewater samples, high levels of enterolactone (581 – 2111 ng/L), daidzein (341 – 1688 ng/L) and enterodiol (60 – 834 ng/L) were detected in raw sewage, but the vast majority of the analysed phytoestrogens were removed effectively in treatment process. The removal rates of the analysed phytoestrogens in the two advanced tertiary treatment plants were > 99%; a case study in one of the treatment plants showed that most of the residual phytoestrogens were removed by biological treatment using activated sludge. In surface …

Corrigendum To ‘‘The Chaperone Action Of Bovine Milk As1- And As2-Caseins And Their Associated Form As-Casein’’ [Arch. Biochem. Biophys. 510 (2011) 42–52], Teresa M. Treweek, David C. Thorn, William E. Price, John A. Carver

William E. Price

No abstract provided.

The Effect Of Dextran On Subunit Exchange Of Αa-Crystallin, A. Ghahghaei, A. Rekas, W. E. Price, J. A. Carver

William E. Price

α-Crystallin, a member of small heat shock protein (sHsp) family, is comprised of αA and αB subunits and acts as a molecular chaperone by interacting with unfolding proteins to prevent their aggregation. The αA-crystallin homopolymer consists of 30-40 subunits that are undergoing dynamic exchange. α-Crystallin and αA-crystallin are poorer chaperones in the presence of the crowding agent, dextran. Using fluorescence resonance energy transfer, it is shown that the αAcrystallin subunit exchange rate strongly increased with temperature. Binding of reduced ovotransferrin to αA-crystallin markedly decreases the rate of subunit exchange, as does the presence of dextran. In addition, in the presence …

The Key Importance Of Soy Isoflavone Bioavailability To Understanding Health Benefits, T. A. Larkin, William E. Price, L. Astheimer

William E. Price

Research over the past two decades has provided significant epidemiological and other evidence for the health benefits of the consumption of soy-based foods. A large number of dietary intervention studies have examined the effects of soy isoflavones on risk factors for cardiovascular disease and hormone-dependent cancers. However, these report large variability in outcome measures, very limited reproducibility between studies and in some cases, controversy between results of clinical trials using dietary soy or soy protein and isoflavone supplementation. This highlights a major gap in our understanding of soy isoflavone uptake, metabolism, distribution, and overall bioavailability. There are many potential factors …

Using Calibration Approaches To Compensate For Remaining Matrix Effects In Quantitative Liquid Chromatography Electrospray Ionization Multistage Mass Spectrometric Analysis Of Phytoestrogens In Aqueous Environmental Samples, Jinguo Kang, Larry A. Hick, William E. Price

William E. Price

Signal suppression is a common problem in quantitative LC-ESI-MSn analysis in environment samples, especially in highly loaded wastewater samples with highly complex matrix. Optimization of sample preparation and improvement of chromatographic separation are prerequisite to improve reproducibility and selectivity. Matrix components may be reduced if not eliminated by a series of sample preparation steps. However, extensive sample preparation can be time-consuming and risk the significant loss of some trace analytes. The best way to further compensate matrix effects is the use of internal standard for each analyte. However, in a multi-component analysis, finding appropriate internal standards for every analyte is …

Index-Compressed Vector Quantisation Based On Index Mapping, Jamshid Shanbehzadeh, Philip Ogunbona

Professor Philip Ogunbona

The authors introduce a novel coding technique which significantly improves the performance of the traditional vector quantisation (VQ) schemes at low bit rates. High interblock correlation in natural images results in a high probability that neighbouring image blocks are mapped to small subsets of the VQ codebook, which contains highly correlated codevectors. If, instead of the whole VQ codebook, a small subset is considered for the purpose of encoding neighbouring blocks, it is possible to improve the performance of traditional VQ schemes significantly. The performance improvement obtained with the new method is about 3dB on average when compared with traditional …

Cmos Sensor Cross-Talk Compensation For Digital Cameras, Wanqing Li, Philip Ogunbona, Yu Shi, Igor Kharitonenko

Professor Philip Ogunbona

This paper presents two algorithms for removing the cross-talk effect in CMOS sensor based color-imaging systems. The algorithms work on the Bayer raw data and have low computational complexity. Experimental results on Macbeth color chart and real images demonstrated that both algorithms can effectively eliminate the cross-talk effect and produce better quality images with conventional color interpolation and correction algorithms designed for CCD image sensors. Complexity of the algorithms is also analyzed.

Finding Distinctive Facial Areas For Face Recognition, Ce Zhan, Wanqing Li, Philip O. Ogunbona

Professor Philip Ogunbona

One of the key issues for local appearance based face recognition methods is that how to find the most discriminative facial areas. Most of the existing methods take the assumption that anatomical facial components, such as the eyes, nose, and mouth, are the most useful areas for recognition. Other more elaborate methods locate the most salient parts within the face according to a pre-specified criterion. In this paper, a novel method is proposed to identify the discriminative facial areas for face recognition. Unlike the existing methods that only analyze the given face, the proposed method identifies the distinctive areas of …

High-Capacity Steganography Using A Shared Colour Palette, G. Brisbane, R. Safavi-Naini, P. Ogunbona

Professor Philip Ogunbona

Seppanen, Makela and Keskinarkaus (SMK) have proposed a high-capacity steganographic technique to conceal information within a colour image. The technique is significant because of the high volume of data that is embedded into pixels but it results in a high level of noise and so the quality of the resulting image is not acceptable. A new type of coding structure is proposed, which maintains a high capacity but lowers the level of noise. Secondly, an adaptive algorithm is used to identify pixel values that have a high capacity to distortion ratio. Also the maximum size of the coding structures is …

On The Computational Complexity Of The Lbg And Pnn Algorithms, Jamshid Shanbehzadeh, Philip Ogunbona

Professor Philip Ogunbona

This correspondence compares the computational complexity of the pair-wise nearest neighbor (PNN) and Linde–Buzo–Gray (LBG) algorithms by deriving analytical expressions for their computational times. It is shown that for a practical codebook size and training vector sequence, the LBG algorithm is indeed more computationally efficient than the PNN algorithm.