225 results on '"Chang, Allan"'
Search Results
202. Development of the Birthweight Appropriateness Quotient: A New Measure of Infant's Size.
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Gibbons, Kristen S., McIntyre, H. David, Mamun, Abdullah, and Chang, Allan M. Z.
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ANTHROPOMETRY , *BIRTH weight , *CONFIDENCE intervals , *STATISTICAL correlation , *DISEASES , *FETAL growth retardation , *GESTATIONAL age , *REGRESSION analysis , *BODY mass index , *HUMAN services programs , *DESCRIPTIVE statistics , *TERTIARY care , *CHILDREN - Abstract
Introduction: The customised birthweight model can be used to improve detection of babies that may be at risk of adverse outcomes associated with abnormal growth, however it is currently used in conjunction with either an intrauterine growth standard or the individualised birthweight ratio (IBR), both of which have significant methodological flaws. Our aim was to investigate the statistical validity of the IBR and attempt to develop a new measurement to represent the appropriateness of an infant's size at birth that will support clinicians in identifying infants requiring further attention. Methods: Routinely collected hospital maternity and neonatal data on singleton, term births from a tertiary Australian hospital were extracted for the time period 1998–2009. The relationships between birthweight, customised birthweight and IBR are investigated using correlation, regression analysis and division of births into groups of < 2500 g, 2500–4000 g and > 4000 g. A new measure, the Birthweight Appropriateness Quotient (BAQ), is developed. The utility of the BAQ is compared with IBR and birthweight to identify infants with a composite neonatal morbidity outcome. Results: Statistical flaws with the IBR due to significant correlation between birthweight and customised birthweight and a heterogenous relationship between these two measurements across the range of birthweight are present. BAQ is uncorrelated with birthweight. Comparison of BAQ and IBR as indicators of adverse neonatal outcome demonstrates that BAQ identifies babies at risk due to their small size and those babies at risk due to inappropriate size. Conclusions for Practice: BAQ is a customised measurement of an infant's size free of the statistical flaws experienced by the IBR with the ability to identify at-risk infants. [ABSTRACT FROM AUTHOR]
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- 2020
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203. Protecting superconducting qubits from phonon mediated decay.
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Rosen, Yaniv J., Horsley, Matthew A., Harrison, Sara E., Holland, Eric T., Chang, Allan S., Bond, Tiziana, and DuBois, Jonathan L
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PHONONS , *FAULT tolerance (Engineering) , *SUPERCONDUCTORS , *BAND gaps , *QUANTUM computing - Abstract
For quantum computing to become fault tolerant, the underlying quantum bits must be effectively isolated from the noisy environment. It is well known that including an electromagnetic bandgap around the qubit operating frequency improves coherence for superconducting circuits. However, investigations of bandgaps to other environmental coupling mechanisms remain largely unexplored. Here, we present a method to enhance the coherence of superconducting circuits by introducing a phononic bandgap around the device operating frequency. The phononic bandgaps block resonant decay of defect states within the gapped frequency range, removing the electromagnetic coupling to phonons at the gap frequencies. We construct a multiscale model that derives the decrease in the density of states due to the bandgap and the resulting increase in defect state T1 times. We demonstrate that emission rates from in-plane defect states can be suppressed by up to two orders of magnitude. We combine these simulations with theory for resonators operating in the continuous-wave regime and show that improvements in quality factors are expected by up to the enhancement in defect T1 times. Furthermore, we use full master equation simulation to demonstrate the suppression of qubit energy relaxation even when interacting with 200 defect states. We conclude with an exploration of device implementation including tradeoffs between fabrication complexity and qubit performance. [ABSTRACT FROM AUTHOR]
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- 2019
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204. Plasmonic black metals in resonant nanocavities.
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Bora, Mihail, Behymer, Elaine M., Dehlinger, Dietrich A., Britten, Jerald A., Larson, Cindy C., Chang, Allan S. P., Munechika, Keiko, Nguyen, Hoang T., and Bond, Tiziana C.
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BLACK shales , *ELECTRICAL harmonics , *RESONATORS , *PLASMONIC Raman sensors , *RAMAN spectroscopy , *ADIABATIC processes - Abstract
We investigate a plasmonic resonant structure tunable from ultra-violet to near infrared wavelengths with maximum absorbance strength over 95% due to a highly efficient coupling with incident light. Additional harmonics are excited at higher frequencies extending the absorbance range to multiple wavelengths. We propose the concept of a plasmonic black metal nanoresonator that exhibits broadband absorbance characteristics by spacing the modes closer through increasing the resonator length and by employing adiabatic plasmonic nano-focusing on the tapered end of the cavity. [ABSTRACT FROM AUTHOR]
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- 2013
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205. Classification of female genito-urinary tract fistula: Inter- and intra-observer correlations.
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Goh, Judith T. W., Krause, Hannah G., Browning, Andrew, and Chang, Allan
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GENITOURINARY organs , *GENITALIA , *VESICOVAGINAL fistula , *BLADDER diseases , *SURGEONS , *GYNECOLOGY - Abstract
Background: Currently, there is no accepted standardized classification for genital tract fistulae. Many classifications have been proposed previously, mainly based on anatomical locations. This is the first paper on inter- and intra-observer correlations using a recently published classification system based on fixed reference points. Aim: To assess intra- and inter-observer reliability of a new classification for genito-urinary fistula. Methods: This is a prospective assessment of women with genito-urinary fistula. Women attending the Fistula Clinic in Ethiopia and Liberia were assessed by three fistula surgeons. The women were assessed in the outpatients and the fistulae were staged. In Liberia, where two surgeons were working together, inter-observer reliability was assessed. All women had the fistulae restaged in the operating theatre and intra-observer concordance was assessed. The clinicians were blinded to the outpatient results. Results: A total of 119 women were recruited. All women had intra-observer assessment and had the fistula examined by the same clinician in the outpatients and in the operating theatre. Fifty of these women had inter-observer assessment with two clinicians assessing the same women. The results demonstrated that this classification system had high concordance in intra- and inter-observer reproducibility. Conclusion: The new classification for genito-urinary fistulae utilizing fixed reference points is a useful tool in describing fistulae. This study has shown that this classification produced consistency in description amongst different clinicians and also by the same clinician in a different consultation. This therefore allows more precise communication of clinical findings. [ABSTRACT FROM AUTHOR]
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- 2009
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206. Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial.
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Strachan, Bryony K., Van Wijngaarden, Willem J., Sahota, Daljit, Chang, Allan, and James, David K.
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FETAL monitoring , *ELECTROCARDIOGRAPHY , *LABOR (Obstetrics) , *EQUIPMENT & supplies ,FETAL heart rate monitoring equipment - Abstract
SummaryBackground: There is a need to improve the sensitivity and specificity of fetal monitoring during labour. We compared the gold standard, cardiotocography, with cardiotocography plus time-interval analysis of the fetal electrocardiogram in fetal surveillance. The aim was to find out whether time-interval analysis decreased the need for operative intervention due to fetal distress.Methods: We did a randomised, prospective trial in five hospitals in the UK, Hong Kong, the Netherlands, and Singapore. 1038 women undergoing high-risk labours were randomly assigned fetal monitoring by cardiotocography alone, or cardiotocography plus fetal electrocardiography (ECG). Outcomes measured were rates of operative intervention, and neonatal outcome. Analysis was by intention to treat.Findings: 515 women were assigned management by cardiotocography, and 523 cardiotocography plus fetal ECG. There was a trend towards fewer operative interventions for presumed fetal distress in the time-interval analysis plus cardiotocography group (63 [13%] vs 78 [16%]), but this was not significant (relative risk 0.80 [95% CI 0.59-1.08], p=0.17). There was no significant difference between groups in the proportion of babies who had an umbilical arterial pH of 7.15 or less (51 [11%] vs 49 [11%]; 1.01 [0.7-1.47]), or in the frequency of unsuspected acidaemia (42 [9%] vs 35 [8%]; 1.17 [0.76-1.79]).Interpretation: The addition of time-interval analysis of the fetal electrocardiogram during labour did not show a significant benefit in decreasing operative intervention. There was no significant difference in neonatal outcome. [ABSTRACT FROM AUTHOR]
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- 2000
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207. Methods for isolation and viability assessment of biological organisms
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Chang, Allan
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- 2015
208. Rapid Clearance of Fetal DNA from Maternal Plasma.
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Lo, Y.M. Dennis, Jun Zhang, Leung, Tse N., Lau, Tze K., Chang, Allan M.Z., and Hjelm, N. Magnus
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FETAL cells from maternal blood , *DNA - Abstract
Investigates the clearance of fetal DNA from maternal plasma after delivery. Generation of higher time-resolution picture of fetal DNA clearance; Correlation between DNA and plasma samples; Role of the plasma nucleases in the clearance of the DNA from the plasma.
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- 1999
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209. Real-Time Tracking of Carbon Dioxide Concentration Using an Optical Microsphere Resonator Sensor.
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Demory B, Echeveria L, Tolfa C, Harrison S, Khitrov V, Chang ASP, and Bond T
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Whispering gallery mode resonator sensors are nondisruptive optical sensors that can detect and monitor perturbations in a gaseous environment. Through its resonant properties of peak wavelength, amplitude, and quality factor (Q factor), changes in concentration can be quantified within seconds and monitored over days with great stability. In addition, the small footprint, low cost, and high sensitivity are ideal properties for a disposable sensor that can be utilized in extreme environments. The large Q factor of the resonant cavity enables long interaction lengths and amplifies the effect of small changes in the background refractive index, which is detectable in picometer shifts of the resonance wavelength. However, this measurement is susceptible to changes in other environmental factors such as temperature, pressure, and humidity, which manifest on the picometer wavelength scale, reinforcing the need to decouple the variables. In this work, we compare the spectral response of different diameter resonators to carbon dioxide, nitrogen, and its mixtures, observing the spectral shifting and broadening of the cavity resonance near 1550 nm. In addition, the effect of environmental temperature on spectral shifting due to the thermo-optic effect is characterized and quantified. Lastly, the gas concentrations are changed in real time to showcase the tracking and recovery capabilities of the resonator sensor., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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- 2024
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210. Prediction of large-for-gestational age infants in relation to hyperglycemia in pregnancy - A comparison of statistical models.
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Gibbons KS, Chang AMZ, Ma RCW, Tam WH, Catalano PM, Sacks DA, Lowe J, and David McIntyre H
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- Bayes Theorem, Blood Glucose, Female, Gestational Age, Humans, Infant, Logistic Models, Pregnancy, Pregnancy Outcome, Diabetes, Gestational diagnosis, Diabetes, Gestational epidemiology, Hyperglycemia diagnosis, Hyperglycemia epidemiology
- Abstract
Aims: Using data from a large multi-centre cohort, we aimed to create a risk prediction model for large-for-gestational age (LGA) infants, using both logistic regression and naïve Bayes approaches, and compare the utility of these two approaches., Methods: We have compared the two techniques underpinning machine learning: logistic regression (LR) and naïve Bayes (NB) in terms of their ability to predict large-for-gestational age (LGA) infants. Using data from five centres involved in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study, we developed LR and NB models and compared the predictive ability and stability between the models. Models were developed combining the risks of hyperglycaemia (assessed in three forms: IADPSG GDM yes/no, GDM subtype, OGTT z-score quintiles), demographic and clinical variables as potential predictors., Results: The two approaches resulted in similar estimates of LGA risk (intraclass correlation coefficient 0.955, 95% CI 0.952, 0.958) however the AUROC for the LR model was significantly higher (0.698 vs 0.682; p < 0.001). When comparing the three LR models, use of individual OGTT z-score quintiles resulted in statistically higher AUROCs than the other two models., Conclusions: Logistic regression can be used with confidence to assess the relationship between clinical and biochemical variables and outcome., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier B.V.)
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- 2021
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211. Low Base-Substitution Mutation Rate in the Germline Genome of the Ciliate Tetrahymena thermophil.
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Long H, Winter DJ, Chang AY, Sung W, Wu SH, Balboa M, Azevedo RBR, Cartwright RA, Lynch M, and Zufall RA
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- Animals, Base Sequence, Germ-Line Mutation, Mutation Rate, Evolution, Molecular, Genome, Protozoan genetics, Selection, Genetic genetics, Tetrahymena thermophila genetics
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Mutation is the ultimate source of all genetic variation and is, therefore, central to evolutionary change. Previous work on Paramecium tetraurelia found an unusually low germline base-substitution mutation rate in this ciliate. Here, we tested the generality of this result among ciliates using Tetrahymena thermophila. We sequenced the genomes of 10 lines of T. thermophila that had each undergone approximately 1,000 generations of mutation accumulation (MA). We applied an existing mutation-calling pipeline and developed a new probabilistic mutation detection approach that directly models the design of an MA experiment and accommodates the noise introduced by mismapped reads. Our probabilistic mutation-calling method provides a straightforward way of estimating the number of sites at which a mutation could have been called if one was present, providing the denominator for our mutation rate calculations. From these methods, we find that T. thermophila has a germline base-substitution mutation rate of 7.61 × 10 - 12 per-site, per cell division, which is consistent with the low base-substitution mutation rate in P. tetraurelia. Over the course of the evolution experiment, genomic exclusion lines derived from the MA lines experienced a fitness decline that cannot be accounted for by germline base-substitution mutations alone, suggesting that other genetic or epigenetic factors must be involved. Because selection can only operate to reduce mutation rates based upon the "visible" mutational load, asexual reproduction with a transcriptionally silent germline may allow ciliates to evolve extremely low germline mutation rates., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)
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- 2016
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212. Customised birthweight models: do they increase identification of at-risk infants?
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Gibbons K, Chang A, Flenady V, Mahomed K, Gardener G, Gray PH, Beckmann M, and Rossouw D
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- Adult, Female, Humans, Infant, Newborn, Male, Obstetric Labor Complications, Pregnancy, Pregnancy Complications, Reference Values, Term Birth, Birth Weight, Fetal Growth Retardation diagnosis, Infant, Newborn, Diseases, Infant, Small for Gestational Age
- Abstract
Aim: The study aims to describe the cohort of women and babies who are classified as small-for-gestational age (SGA) at term by both an Australian customised birthweight model (CBM) and a commonly used population-based standard, and to investigate and compare the utility of these models in identifying babies at risk of experiencing adverse outcomes, Methods: Routinely collected data on 54 890 singleton-term births at the Mater Mothers' Hospitals, Brisbane, with birthweight less than 4000 g between January 1997 and December 2008, was extracted. Each birth was classified as SGA (<10th centile) or not SGA by either and/or both methods: population-based standards (SGApop ) and CBM (SGAcust ). Babies classified as SGApop , SGAcust or SGAboth were compared with those not classified as SGA by both methods using relative risk and 95% confidence interval, and those only classified as SGAcust were compared with those only classified as SGApop . Maternal demographics, maternal risk factors for fetal growth restriction, pregnancy and labour complications and adverse neonatal outcomes are reported., Results: A total of 4768 (8.7%) births were classified as SGApop , while 6479 (11.8%) were SGAcust of whom 4138 (63.9%) were also classified as SGApop . Maternal risk factors such as smoking and hypertension were statistically higher for the SGAcust group when compared with SGApop . For the majority of adverse neonatal outcomes, a trend was noted to increased identification using the CBM., Conclusion: The CBM provides a modest improvement when compared to a population-based standard to identity term infants at birth who are at risk of adverse neonatal outcomes., (© 2013 The Authors. Journal of Paediatrics and Child Health © 2013 Paediatrics and Child Health Division (Royal Australasian College of Physicians).)
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- 2013
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213. A test of agreement of customised birthweight models.
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Gibbons KS, Chang AM, Flenady VJ, Mahomed K, Gray PH, Gardener GJ, and Rossouw D
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- Australia, Confidence Intervals, Female, Fetal Development, Gestational Age, Humans, Infant, Newborn, Reference Values, Birth Weight physiology, Models, Biological, White People
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Background: The objective of this study was to determine whether the physiological effects on birthweight as described by customised birthweight models (CBMs) from various populations and locations are consistent when applied to a single sample., Methods: The predicted birthweight was calculated for 52 826 White-European singleton term births between 1997 and 2008 from a large Australian hospital using the same set of variables from 12 published CBMs. The accuracy of prediction was tested against both the actual birthweight and a reference model. Intraclass correlation coefficients (ICCs) along with 95% confidence intervals of the measurements, paired differences (predicted-actual birthweight) and absolute values of the paired differences are reported., Results: The average difference in predicted and actual birthweight was <200 g for all CBMs, with ICCs for all but one model indicating fair agreement (between 0.3 and 0.5). When compared with the reference model, eight of the 11 models had a difference in predicted birthweight of <220 g, and the ICCs indicated that the majority of models had strong agreement., Conclusion: All published CBMs demonstrated ability to predict birthweight with reasonable accuracy. The effects of maternal and fetal characteristics on birthweight appear to be consistent across birthweight models. This finding is a further step in validating the CBM, and provides greater evidence for the creation of a global model., (© 2013 Blackwell Publishing Ltd.)
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- 2013
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214. Nanopillar array on a fiber facet for highly sensitive surface-enhanced Raman scattering.
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Yang X, Ileri N, Larson CC, Carlson TC, Britten JA, Chang AS, Gu C, and Bond TC
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A highly-sensitive optical fiber surface-enhanced Raman scattering (SERS) sensor has been developed by interference lithography. While one facet of the optical fiber is patterned with silver-coated nanopillar array as a SERS platform, the other end of the probe is used, in a remote end detection, to couple the excitation laser into the fiber and send the SERS signal to the spectrometer. SERS performance of the probe is characterized using trans-1,2-bis(4-pyridyl)-ethylene (BPE) monolayer and an enhancement factor of 1.2 × 10(7) can be achieved by focusing the laser directly onto the nanopillar array (front end detection). We also demonstrate that this probe can be used for in situ remote sensing of toluene vapor by the remote end detection. Such a fiber SERS probe shows great potential for molecular detection in various sensing applications.
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- 2012
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215. Validation and refinement of an Australian customised birthweight model using routinely collected data.
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Gibbons K, Chang A, Flenady V, Mahomed K, Gardener G, and Gray PH
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- Adult, Australia, Female, Humans, Infant, Newborn, Male, Birth Weight, Models, Biological
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Background: Published customised birthweight models designed to account for individual constitutional variation have not been validated in an independent population to verify the results., Aims: To validate our previously reported customised birthweight model with additional data from the same hospital and to revise this model using a larger, more refined dataset., Methods: With the accumulation of further data, a set of coefficients was derived based on the 12-year dataset. Using shrinkage statistics, records between July 2005 and December 2008 were used to validate the model. Stepwise multiple regression using a more refined dataset of births between January 1997 and December 2008 was used to derive updated coefficients. Performance of the model was assessed using individualised birthweight ratios and the absolute difference between customised and actual birthweight., Results: Previous coefficients were validated, with shrinkage of less than 1%, indicating that the model is stable over time. An updated set of coefficients based on a dataset of 61,630 births, including refined ethnicity categories and the addition of a smoking term, is presented, which resulted in improved model statistics (primarily an improved multiple correlation coefficient of 0.51)., Conclusion: The customised birthweight model appears to be stable over time in the same hospital. Initial comparisons to literature indicate that models from different geographic locations may lead to similar coefficients; but, there remains a need to formally assess this aspect of birthweight models. The updated coefficients differ slightly from those previously published and are considered superior because of refinement in the dataset., (© 2010 The Authors. Australian and New Zealand Journal of Obstetrics and Gynaecology © 2010 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.)
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- 2010
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216. Rigorous surface enhanced Raman spectral characterization of large-area high-uniformity silver-coated tapered silica nanopillar arrays.
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Gartia MR, Xu Z, Behymer E, Nguyen H, Britten JA, Larson C, Miles R, Bora M, Chang AS, Bond TC, and Liu GL
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- Nanostructures ultrastructure, Phenols, Reproducibility of Results, Sulfhydryl Compounds, Surface Properties, Nanostructures chemistry, Silicon Dioxide chemistry, Silver chemistry, Spectrum Analysis, Raman methods
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Surface enhanced Raman spectroscopy (SERS) has been increasingly utilized as an analytical technique with significant chemical and biological applications (Qian et al 2008 Nat. Biotechnol. 26 83; Fujita et al 2009 J. Biomed. Opt. 14 024038; Chou et al 2008 Nano Lett.8 1729; Culha et al 2003 Anal. Chem. 75 6196; Willets K A 2009 Anal. Bioanal. Chem. 394 85; Han et al 2009 Anal. Bioanal. Chem. 394 1719; Sha et al 2008 J. Am. Chem. Soc. 130 17214). However, production of a robust, homogeneous and large-area SERS substrate with the same ultrahigh sensitivity and reproducibility still remains an important issue. Here, we describe a large-area ultrahigh-uniformity tapered silver nanopillar array made by laser interference lithography on the entire surface of a 6 inch wafer. Also presented is the rigorous optical characterization method of the tapered nanopillar substrate to accurately quantify the Raman enhancement factor, uniformity and repeatability. An average homogeneous enhancement factor of close to 10(8) was obtained for benzenethiol adsorbed on a silver-coated nanopillar substrate.
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- 2010
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217. Hormonal and metabolic factors associated with variations in insulin sensitivity in human pregnancy.
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McIntyre HD, Chang AM, Callaway LK, Cowley DM, Dyer AR, Radaelli T, Farrell KA, Huston-Presley L, Amini SB, Kirwan JP, and Catalano PM
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- Adult, Body Mass Index, Cholesterol blood, Cross-Sectional Studies, Fatty Acids, Nonesterified blood, Female, Glucose Tolerance Test, Humans, Insulin blood, Insulin-Like Growth Factor Binding Protein 3 blood, Insulin-Like Growth Factor Binding Proteins blood, Insulin-Like Growth Factor I metabolism, Insulin-Like Growth Factor II metabolism, Leptin blood, Prospective Studies, Regression Analysis, Triglycerides blood, Tumor Necrosis Factor-alpha blood, Pregnancy blood
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Objective: The objective of this study was to determine maternal hormonal and metabolic factors associated with insulin sensitivity in human pregnancy., Research Design and Methods: This was a prospective observational cross-sectional study of 180 normal pregnant women, using samples collected at the time of a blinded oral glucose tolerance test (OGTT) between 24 and 32 weeks' gestation as an ancillary to the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. The study was conducted at two public university teaching hospitals, Cleveland, Ohio, and Brisbane, Australia. Fasting maternal serum cholesterol, triglycerides, free fatty acids, insulin, leptin, tumor necrosis factor-alpha, placental growth hormone (PGH), insulin-like growth factors (IGFs) 1 and 2, and insulin-like growth factor binding proteins (IGFBPs) 1 and 3 were assayed. Correlation and multiple regression analyses were used to determine factors associated with maternal insulin sensitivity (IS) estimated using both OGTT-derived (IS(OGTT)) and fasting (using the homeostasis model assessment [HOMA]; IS(HOMA)) insulin and glucose concentrations., Results: Insulin sensitivity correlated (r = x and y for IS(OGTT) and IS(HOMA,) respectively) with fasting maternal serum leptin (-0.44 and -0.52), IGFBP1 (0.42 and 0.39), and triglycerides (-0.31 and -0.27). These factors were significantly associated with insulin sensitivity in multiple regression analyses (adjusted R(2) 0.44 for IS(OGTT) and IS(HOMA)). These variables explained more than 40% of the variance in estimates of insulin sensitivity., Conclusions: Maternal hormonal and metabolic factors related to the placenta, adipose tissue, and the growth hormone axis are associated with the variation in insulin sensitivity seen during normal human pregnancy.
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- 2010
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218. Predicting the risk of failure of closure of obstetric fistula and residual urinary incontinence using a classification system.
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Goh JT, Browning A, Berhan B, and Chang A
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- Adult, Female, Fibrosis, Humans, Pregnancy, Prospective Studies, Risk Assessment, Risk Factors, Treatment Failure, Vagina pathology, Vaginal Fistula pathology, Obstetric Labor Complications surgery, Urinary Incontinence etiology, Vaginal Fistula complications, Vaginal Fistula surgery
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The aim of this study is to assess the possibility of predicting the risk of failure of closure and post-fistula urinary incontinence. Women attending the fistula clinics were assessed pre-operatively, and fistulae were staged prospectively, using a previously published classification system. Assessment for fistula closure and residual urinary incontinence was performed, prior to discharge. Of the 987 women who were assessed, 960 had successful closure of their fistulae. Of those with successful closure, 229 complained of urinary incontinence following surgery. Women with fistulae located closest to the external urinary meatus had the highest rate of urinary incontinence following fistula closure. Women with significant vaginal scarring and circumferential fistulae also had significantly higher rates of urinary incontinence and higher risk of failure of closure. The classification used is able to predict women at risk of post-fistula urinary incontinence and failure of closure.
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- 2008
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219. Design of optical path for wide-angle gradient-index antireflection coatings.
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Chen M, Chang HC, Chang AS, Lin SY, Xi JQ, and Schubert EF
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What we believe to be a new principle is introduced for the design and selection of gradient-index antireflection profiles that are effective over a wide range of incident angles as well as wavelengths at a given physical film thickness. It is shown that at oblique incidence the smoothness of the optical path of incident light inside a gradient-index film has a crucial effect on the overall reflection. Thus the smoothness of variations in refractive angle (rather than that of the index profile itself) needs to be maximized for wide-angle operation. As an example, the performance of Gaussian and Quintic profiles at large incident angles are considered in light of this point of view.
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- 2007
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220. Customised birthweight: coefficients for an Australian population and validation of the model.
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Pain S, Chang AM, Flenady V, and Chan FY
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- Australia, Body Height, Body Mass Index, Female, Humans, Infant, Newborn, Male, Normal Distribution, Reference Values, Birth Weight, Models, Statistical
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Background: Published birthweight references in Australia do not fully take into account constitutional factors that influence birthweight and therefore may not provide an accurate reference to identify the infant with abnormal growth. Furthermore, studies in other regions that have derived adjusted (customised) birthweight references have applied untested assumptions in the statistical modelling., Aims: To validate the customised birthweight model and to produce a reference set of coefficients for estimating a customised birthweight that may be useful for maternity care in Australia and for future research., Methods: De-identified data were extracted from the clinical database for all births at the Mater Mother's Hospital, Brisbane, Australia, between January 1997 and June 2005. Births with missing data for the variables under study were excluded. In addition the following were excluded: multiple pregnancies, births less than 37 completed week's gestation, stillbirths, and major congenital abnormalities. Multivariate analysis was undertaken. A double cross-validation procedure was used to validate the model., Results: The study of 42,206 births demonstrated that, for statistical purposes, birthweight is normally distributed. Coefficients for the derivation of customised birthweight in an Australian population were developed and the statistical model is demonstrably robust., Conclusions: This study provides empirical data as to the robustness of the model to determine customised birthweight. Further research is required to define where normal physiology ends and pathology begins, and which segments of the population should be included in the construction of a customised birthweight standard.
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- 2006
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221. The prevalence and impact of overweight and obesity in an Australian obstetric population.
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Callaway LK, Prins JB, Chang AM, and McIntyre HD
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- Adult, Australia epidemiology, Body Mass Index, Female, Hospitals, Maternity, Humans, Infant, Newborn, Obesity complications, Pregnancy, Prevalence, Retrospective Studies, Obesity epidemiology, Overweight, Pregnancy Complications epidemiology, Pregnancy Outcome
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Objective: To assess the prevalence and impact of overweight and obesity in an Australian obstetric population., Design, Setting and Participants: The Mater Mother's Hospital (MMH), South Brisbane, is an urban tertiary referral maternity hospital. We reviewed data for the 18 401 women who were booked for antenatal care at the MMH, delivered between January 1998 and December 2002, and had a singleton pregnancy. Of those women, 14 230 had an estimated pre-pregnancy body mass index (BMI) noted in their record; 2978 women with BMI < or = 20 kg/m2 were excluded from further study; the remaining 11 252 women were divided into four categories: "normal" (BMI 20.01-25 kg/m(2)), "overweight" (BMI 25.01-30 kg/m(2)), "obese" (BMI 30.01-40 kg/m(2)) and "morbidly obese" (BMI > 40 kg/m(2))., Main Outcome Measures: Prevalence of overweight and obesity in an obstetric population; maternal, peripartum and neonatal outcomes associated with raised BMI., Results: Of the 14 230 women, 6443 (45%) were of normal weight, and 4809 (34%) were overweight, obese or morbidly obese. Overweight, obese and morbidly obese women were at increased risk of adverse outcomes (figures represent adjusted odds ratio [AOR] [95% CI]): hypertensive disorders of pregnancy (overweight 1.74 [1.45-2.15], obese 3.00 [2.40-3.74], morbidly obese 4.87 [3.27-7.24]); gestational diabetes (overweight 1.78 [1.25-2.52], obese 2.95 [2.05-4.25], morbidly obese 7.44 [4.42-12.54]); hospital admission longer than 5 days (overweight 1.36 [1.13-1.63], obese 1.49 [1.21-1.86], morbidly obese 3.18 [2.19-4.61]); and caesarean section (overweight 1.50 [1.36-1.66], obese 2.02 [1.79-2.29], morbidly obese 2.54 [1.94-3.32]). Neonates born to obese and morbidly obese women had an increased risk of birth defects (obese 1.58 [1.02-2.46], morbidly obese 3.41 [1.67-6.94]); and hypoglycaemia (obese 2.57 [1.39-4.78], morbidly obese 7.14 [3.04-16.74]). Neonates born to morbidly obese women were at increased risk of admission to intensive care (2.77 [1.81-4.25]); premature delivery (< 34 weeks' gestation) (2.13 [1.13-4.01]); and jaundice (1.44 [1.09-1.89])., Conclusions: Overweight and obesity are common in pregnant women. Increasing BMI is associated with maternal and neonatal outcomes that may increase the costs of obstetric care. To assist in planning health service delivery, we believe that BMI should be routinely recorded on perinatal data collection sheets.
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- 2006
- Full Text
- View/download PDF
222. Chronic venous leg ulcers: effect of a community nursing intervention on pain and healing.
- Author
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Edwards H, Courtney M, Finlayson K, Lindsay E, Lewis C, Shuter P, and Chang A
- Subjects
- Aged, Aged, 80 and over, Chronic Disease, Female, Humans, Male, Middle Aged, Models, Nursing, Nursing Assessment, Nursing Evaluation Research, Pain diagnosis, Pain prevention & control, Patient Education as Topic, Queensland, Referral and Consultation, Skin Care methods, Skin Care nursing, Social Support, Treatment Outcome, Varicose Ulcer complications, Community Health Nursing organization & administration, Pain etiology, Self-Help Groups organization & administration, Varicose Ulcer nursing, Wound Healing
- Abstract
Aim: To investigate the effectiveness of a new community nursing model of care for clients with chronic leg ulcers in terms of levels of pain and ulcer healing., Method: A randomised controlled trial comparing the new model of care with standard community nursing care was conducted with a sample of 56 clients with chronic venous leg ulcers, 28 clients in the intervention group and 28 in the control group. Data were collected on admission to the study and at 12 weeks from admission., Results: Significant improvements in levels of pain and ulcer healing were found in the intervention group receiving the new model of care., Conclusion: Results from this study have implications for health professionals providing care for clients with chronic leg ulcers.
- Published
- 2005
- Full Text
- View/download PDF
223. Using group-sequential analysis to achieve the optimal sample size.
- Author
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Rogers MS, Chang AM, and Todd S
- Subjects
- Sampling Studies, Data Interpretation, Statistical, Randomized Controlled Trials as Topic, Sample Size
- Published
- 2005
- Full Text
- View/download PDF
224. Postpartum urinary retention.
- Author
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Yip SK, Sahota D, Pang MW, and Chang A
- Subjects
- Female, Humans, Pregnancy, Puerperal Disorders diagnosis, Puerperal Disorders therapy, Urinary Retention diagnosis, Urinary Retention therapy
- Published
- 2004
- Full Text
- View/download PDF
225. Four-year follow-up of women who were diagnosed to have postpartum urinary retention.
- Author
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Yip SK, Sahota D, Chang AM, and Chung TK
- Subjects
- Female, Follow-Up Studies, Humans, Logistic Models, Prevalence, Time Factors, Puerperal Disorders complications, Urinary Incontinence, Stress epidemiology, Urinary Retention complications
- Abstract
Objective: The purpose of this study was to evaluate the long-term prevalence of urinary incontinence in women with postpartum urinary retention., Study Design: A telephone interview was conducted by contacting a cohort of 691 women who delivered vaginally 4 years ago, of which 101 women had been diagnosed as having postpartum urinary retention. A structured telephone interview consisted of 9 questions on the possible outcomes of postpartum urinary retention., Results: Of the original cohort of 691 women, 394 women were contacted. Seventy-three women had had postpartum urinary retention, and 321 women had not. In women who had had postpartum urinary retention, the prevalence of the outcome variables were urinary stress incontinence (28.8%), fecal incontinence (2.7%), frequency (39.1%), nocturia (65.2%), urgency (26.1%), urge incontinence (26.1%), and coital incontinence (13%). Analyses showed that there was no significant difference between women with and without urinary retention., Conclusion: Women who had had postpartum urinary retention did not have a higher prevalence of urinary stress incontinence.
- Published
- 2002
- Full Text
- View/download PDF
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