Real-Time Tracking of Carbon Dioxide Concentration Using an Optical Microsphere Resonator Sensor.

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.

Prediction of large-for-gestational age infants in relation to hyperglycemia in pregnancy - A comparison of statistical models.

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.

Development of the Birthweight Appropriateness Quotient: A New Measure of Infant's Size.

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.

Low Base-Substitution Mutation Rate in the Germline Genome of the Ciliate Tetrahymena thermophil.

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.

Customised birthweight models: do they increase identification of at-risk infants?

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.

A test of agreement of customised birthweight models.

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.

Nanopillar array on a fiber facet for highly sensitive surface-enhanced Raman scattering.

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.

Validation and refinement of an Australian customised birthweight model using routinely collected data.

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.

Rigorous surface enhanced Raman spectral characterization of large-area high-uniformity silver-coated tapered silica nanopillar arrays.

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.

Plasmon resonant cavities in vertical nanowire arrays.

We investigate tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides. Resonances are observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors over 10(3) are possible due to plasmon focusing in the interwire space.

Hormonal and metabolic factors associated with variations in insulin sensitivity in human pregnancy.

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.

Classification of female genito-urinary tract fistula: Inter- and intra-observer correlations.

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.

Electrostatic force assisted exfoliation of prepatterned few-layer graphenes into device sites.

We present a novel fabrication method for incorporating nanometer to micrometer scale few-layer graphene (FLG) features onto substrates with electrostatic exfoliation. We pattern highly oriented pyrolytic graphite using standard lithographic techniques and subsequently, in a single step, exfoliate and transfer-print the prepatterned FLG features onto a silicon wafer using electrostatic force. We have successfully demonstrated the exfoliation/printing of 18 nm wide FLG nanolines and periodic arrays of 1.4 mum diameter pillars. Furthermore, we have fabricated graphene nanoribbon transistors using the patterned graphene nanoline. Our electrostatic force assisted exfoliation/print process does not need additional adhesion layers and could be stepped and repeated to deliver the prepatterned graphitic material over wafer-sized areas and allows the construction of graphene-based integrated circuits.

Predicting the risk of failure of closure of obstetric fistula and residual urinary incontinence using a classification system.

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.

Prepartum and intrapartum caesarean section rates at Mater Mothers' Hospital Brisbane 1997-2005.

AIM: To document the rise in prepartum and intrapartum caesarean section and the demographic and medical factors contributing to the rise. METHODS: Data from 52,423 deliveries between January 1997 to May 2005 were analysed for yearly change in caesarean section rates and multiple demographic and medical factors. RESULTS: The prepartum caesarean section rate increased by 1.6% per year and the intrapartum caesarean section rate by 0.8% per year. There was no increase in the overall prevalence of obesity, short stature, advanced maternal age, medical complications or previous caesarean section. There were significant increases in nulliparity, private care, induction of labour and the use of electronic monitoring, but these were insufficient to explain the magnitude of the rise. CONCLUSION: The increase in prepartum and intrapartum caesarean section displayed was not fully explained by medical and demographic changes in the population.

Design of optical path for wide-angle gradient-index antireflection coatings.

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.

Visible three-dimensional metallic photonic crystal with non-localized propagating modes beyond waveguide cutoff.

We report experimental realization of a 5-layer three-dimensional (3D) metallic photonic crystal structure that exhibits characteristics of a 3D complete bandgap extending from near-infrared down to visible wavelength at around 650 nm. The structure also exhibits a new kind of non-localized passband mode in the infrared far beyond its metallic waveguide cutoff. This new passband mode is drastically different from the well-known defect mode due to point or line defects. Three-dimensional finite-difference-time-domain simulations were carried out and the results suggest that the passband modes are due to intra-structure resonances.

Path analysis modeling indicates free transport increases ambulance use for minor indications.

INTRODUCTION: Clinically unnecessary ambulance transport is increasing, diverting limited resources from patients needing ambulance transport. It was anecdotally observed that inappropriate ambulance use increased after abolition of a direct patient cost for ambulance transport. HYPOTHESIS: In July 2003, direct patient fees were abolished in favor of a universally applied ambulance levy, potentially leading to increased ambulance use by patients with low illness acuity and admission rates. METHODS: The influence of age, illness acuity, and need for admission on ambulance use was assessed for 55,397 emergency department attendances in 2002 and 2004. Ambulance users were compared with nonusers in both years and attendances for 2002 compared with 2004 using chi-square test for two groups. Logistic regression provided a multivariate model leading to ambulance use. Path analysis modeling to assess interrelationships between factors associated with ambulance use was developed. RESULTS: Ambulance users in both years were older, had more acute illness, and had greater need for admission compared with nonusers. The odds ratio (OR) of arrival by ambulance in 2004 compared with 2002 was 1.14 (95% confidence interval, [CI], 1.12 to 1.17). In 2002, ambulance users were older (OR, 1.42; 95% CI, 1.40 to 1.43), were more likely to need admission (OR, 2.28; 95% CI, 2.16 to 2.4) and had higher illness acuity (OR, 2.02; 95% CI, 1.94 to 2.09). There was a negative correlation between 2004 and illness acuity. CONCLUSIONS: Ambulance use increased in 2004 after patient transport fees were abolished. Increased use was associated with decreased age, clinical acuity, and admission need. Abolishing direct patient cost stimulates ambulance use, potentially including inappropriate transport. Path analysis to assess the effect of changed funding on ambulance use could be used to the influence of other locally relevant factors contributing to ambulance use.

Customised birthweight: coefficients for an Australian population and validation of the model.

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.

The prevalence and impact of overweight and obesity in an Australian obstetric population.

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.