Narrow Confidence Limits Research Articles

Exploring the status of the Indonesian deep demersal fishery using length-based stock assessments

The deep demersal snapper-grouper fishery in Indonesia is a data-poor fisheries resource that provides food security and a source of income to millions globally. Owing to an ongoing crew-operated data recording system implemented in Indonesia since 2015, the stocks of this fishery can now be assessed using length-frequency data and updated life-history parameters. Here, we use two length-based methods, one that is fishery-specific and another that is more generalized, to assess the status of Indonesian stocks. Specifically, we develop a literature-based assessment method based on a patchwork of conventional approaches but tailored to the studied stocks, and compare it with a newly established and broadly applicable length-based Bayesian biomass estimation method (LBB). The methods were applied to 16 stocks from 4 Indonesian Fisheries Management Areas and were compared based on simulations, as well as the convergence of the resulting stock status classification and uncertainty of the results. Analyzing the effect of using the literature-based species/family-specific life-history parameter values for asymptotic length (Linf) and relative natural mortality (M/K) in LBB showed that different values do affect the estimated biomass indicator. Nevertheless, in more than half the cases, the stock status classification did not differ between the two methods, while LBB results became more reliable with narrower confidence limits. Simulations, as well as similar status indicators between the two models support the value of the literature-based approach as an assessment methodology for the Indonesian deep demersal fisheries. Narrower confidence ranges highlight the importance of using fishery-specific information when applying generalized stock assessment methods. While most catches had few immature fish, half of the assessed stocks were consistently shown to have low biomass, indicating that important Indonesian stocks are at high risk of overfishing.

Comparison of matrix-effect corrections for ordinary and uncertainty weighted linear regressions and determination of major element mean concentrations and total uncertainties of sixty-two international geochemical reference materials from wavelength-dispersive X-ray fluorescence spectrometry

In X-ray fluorescence (XRF) spectrometry, matrix-effect corrections for two types of linear regressions (ordinary and uncertainty-based weighted) have been performed for the first time and compared for the determination of major elements in rocks and minerals. The analytical data from different laboratories for 62 international geochemical reference materials (GRMs) were first processed to obtain better estimates of the mean values, along with lower uncertainties (narrower confidence limits of the mean), which were used in the XRF calibrations. The blank intensities were subtracted from the response for each GRM and the respective uncertainties were estimated. The uncertainty-based weighted least-squares linear regression (UWLR) model, being statistically more appropriate than the ordinary least-squares linear regression (OLR) model, provided more reliable regression equations than the OLR. All calculations and matrix-effect corrections were achieved through a newly developed online computer program. Similarly, matrix-effect corrections involving 11 α and 26 α (alphas) are presented and compared. The best UWLR method involving 26 α was successfully applied to the 62 GRMs and 4 similarly complex rock matrices as the calibrators. Both evaluations confirmed the usefulness of the UWLR model. This UWLR model was also compared with the OLR 26 α model for 62 GRMs treated as unknowns and shown to perform better. Thus, the UWLR model, along with the proposed matrix-effect correction method of 26 α, can be recommended as the most appropriate procedure for the calibration of XRF instruments, instead of the commonly used OLR models. This is the first time when 26 α are advantageously in a better estimate of influence coefficients used for major element determinations in rock and mineral samples. Because the UWLR calibration is based on a large number of GRMs of many rock and mineral types, it should be useful for all kinds of geological materials.

Statistically Coherent Calibration of X-Ray Fluorescence Spectrometry for Major Elements in Rocks and Minerals

We applied both the ordinary linear regression (OLR) and the new uncertainty weighted linear regression (UWLR) models for the calibration and comparison of a XRF machine through 59 geochemical reference materials (GRMs) and a procedure blank sample. The mean concentration and uncertainty data for the GRMs used for the calibrations (Supplementary Materials) (available here) filewere achieved from an up-to-date compilation of chemical data and their processing from well-known discordancy and significance tests. The drift-corrected XRF intensity and its uncertainty were determined from mostly duplicate pressed powder pellets. The comparison of the OLR (linear correlation coefficient r∼0.9523–0.9964 and 0.9771–0.9999, respectively, for before and after matrix correction) and UWLR models (r∼0.9772–0.9976 and 0.9970–0.9999, respectively) clearly showed that the latter with generally higher values of r is preferable for routine calibrations of analytical procedures. Both calibrations were successfully applied to rock matrices, and the results were generally consistent with those obtained in other laboratories although the UWLR model showed mostly narrower confidence limits of the mean (slope and intercept) or lower uncertainties than the OLR. Similar sensitivity (∼2.69–46.17 kc·s−1·%−1 for the OLR and ∼2.78–59.69 kc·s−1·%−1 for the UWLR) also indicated that the UWLR could advantageously replace the OLR model. Another novel aspect is that the total uncertainty can be reported for individual chemical data. If the analytical instruments were routinely calibrated from the UWLR model, this action would make the science of geochemistry more quantitative than at present.

Effects of food items and related nutrients on metabolic syndrome using Bayesian multilevel modelling using the Tehran Lipid and Glucose Study (TLGS): a cohort study

ObjectivesDiet and nutrition might play an important role in the aetiology of metabolic syndrome (MetS). Most studies that examine the effects of food intake on MetS have used conventional statistical...

PM2.5 and ozone, indicators of air quality, and acute deaths in California, 2004–2007

Since the London Great Smog of 1952 was estimated to have killed over 4000 people, scientists have studied the relationship between air quality and acute mortality. Currently, the association between air quality and acute deaths is usually taken as evidence for causality. As air quality has markedly improved since 1952, do contemporary datasets support this view? We use a large dataset, eight air basins in California for the years 2004–2007, to examine the possible association of ozone and PM2.5 with acute deaths after statistically removing seasonal and weather effects. Our analysis dataset is available on request. We conducted a regression-corrected, case-crossover analysis for all non-accidental deaths age 75 and older. We used stepwise regression to examine three causes of death. After seasonal and weather adjustments, there was essentially no predictive power of ozone or PM2.5 for acute deaths. The case-crossover analysis produced odds ratio very close to 1.000 (no effect). The very narrow confidence limits indicated good statistical power. We study recent air quality in both time-stratified, symmetric, bidirectional case-crossover and time series regression and both give consistent results. There is no statistically significant association between either ozone or PM2.5 and acute human mortality. In the absence of an association, causality is in question.

Effects of Mindfulness Practice on Performance-Relevant Parameters and Performance Outcomes in Sports: A Meta-Analytical Review.

Mindfulness as a present-oriented form of mental training affects cognitive processes and is increasingly considered meaningful for sport psychological training approaches. However, few intervention studies have examined the effects of mindfulness practice on physiological and psychological performance surrogates or on performance outcomes in sports. The aim of the present meta-analytical review was to examine the effects of mindfulness practice or mindfulness-based interventions on physiological and psychological performance surrogates and on performance outcomes in sports in athletes over 15years of age. A structured literature search was conducted in six electronic databases (CINAHL, EMBASE, ISI Web of Knowledge, PsycINFO, MEDLINE and SPORTDiscus). The following search terms were used with Boolean conjunction: (mindful* OR meditat* OR yoga) AND (sport* OR train* OR exercis* OR intervent* OR perform* OR capacity OR skill*) AND (health* OR adult* OR athlete*). Randomized and non-randomized controlled studies that compared mindfulness practice techniques as an intervention with an inactive control or a control that followed another psychological training program in healthy sportive participants were screened for eligibility. Eligibility and study quality [Physiotherapy Evidence Database (PEDro)] scales were independently assessed by two researchers. A third independent researcher was consulted to achieve final consensus in case of disagreement between both researchers. Standardized mean differences (SMDs) were calculated as weighted Hedges' g and served as the main outcomes in comparing mindfulness practice versus control. Statistical analyses were conducted using a random-effects inverse-variance model. Nine trials of fair study quality (mean PEDro score 5.4, standard deviation 1.1) with 290 healthy sportive participants (athletics, cyclists, dart throwers, hammer throwers, hockey players, hurdlers, judo fighters, rugby players, middle-distance runners, long-distance runners, shooters, sprinters, volleyball players) were included. Intervention time varied from 4weeks to over 2years. The practice frequency lasted from twice daily to just once a week, and the mean session time covered 50-60min. In favor of mindfulness practice compared with the control condition, large effects with narrow confidence limits and low heterogeneity were found for mindfulness scores [SMD 1.03, 90% confidence interval (CI) 0.67-1.40, p<0.001, I 2=17%]. Physiological performance indices depicted wide confidence limits accompanied with very large heterogeneity. However, the effect sizes remained very large, with confidence limits that did not overlap zero (SMD 3.62, 90% CI 0.03-7.21, p=0.10, I 2=98%). Moderate to large effects were observed for both psychological performance surrogates (SMD 0.72, 90% CI 0.46-0.98, p<0.001, I 2=14%) and performance outcomes in shooting and dart throwing (SMD 1.35, 90% CI 0.61-2.09, p=0.003, I 2=82%). Mindfulness practice consistently and beneficially modulates mindfulness scores. Furthermore, physiological and psychological surrogates improved to a meaningful extent following mindfulness practice, as well as performance outcomes in shooting and dart throwing. It seems reasonable to consider mindfulness practice strategies as a regular complementary mental skills training approach for athletes, at least in precision sports; however, more high-quality, randomized, controlled trials on mindfulness practice and performance improvements in diverse sport settings are needed.

Joint-specific risk of impaired function in fibrodysplasia ossificans progressiva (FOP).

Fibrodysplasia ossificans progressiva (FOP) causes progressive disability due to heterotopic ossification from episodic flare-ups. Using data from 500 FOP patients (representing 63% of all known patients world-wide), age- and joint-specific risks of new joint involvement were estimated using parametric and nonparametric statistical methods. Compared to data from a 1994 survey of 44 individuals with FOP, our current estimates of age- and joint-specific risks of new joint involvement are more accurate (narrower confidence limits), based on a wider range of ages, and have less bias due to its greater comprehensiveness (captures over three-fifths of the known FOP patients worldwide). For the neck, chest, abdomen, and upper back, the estimated hazard decreases over time. For the jaw, lower back, shoulder, elbow, wrist, fingers, hip, knee, ankle, and foot, the estimated hazard increases initially then either plateaus or decreases. At any given time and for any anatomic site, the data indicate which joints are at risk. This study of approximately 63% of the world's known population of FOP patients provides a refined estimate of risk for new involvement at any joint at any age, as well as the proportion of patients with uninvolved joints at any age. Importantly, these joint-specific survival curves can be used to facilitate clinical trial design and to determine if potential treatments can modify the predicted trajectory of progressive joint dysfunction.

Concordance of 18F-FDG PET Uptake in Tumor and Normal Tissues on PET/MRI and PET/CT.

The aim of this study was to assess the concordance of PET measurements of F-FDG uptake in tumor and normal tissues obtained on Australia's first clinical PET/MRI scanner in comparison to PET/CT, with comparison against published data. One hundred subjects were prospectively recruited from an unselected, heterogeneous group of cancer patients to undergo F-FDG PET/CT and PET/MRI on the same day. SUVs of physiological regions and tumor tissues obtained by PET/MRI and PET/CT were compared and benchmarked against existing published data. Physiological activity was measured in the thoracic aorta and right lobe of the liver. Tumor SUVs were analyzed by cancer type, body region, and a combined group of all lesions. There was an excellent correlation between SUV measurements in tumor lesions obtained by PET/MRI and PET/CT, across all body regions and in all tumor types studied. There was a less robust correlation for SUVs measured in areas of physiological activity, but the level of agreement still fell within 2 SDs of mean. Data from this study showed comparable or smaller systemic biases and narrower confidence limits than existing studies in the literature comparing SUVs from PET/MRI and PET/CT. F-FDG PET/MRI appears promising as an adjunct or alternative to PET/CT for quantitative evaluation in oncology, independent of body region and tumor type, across a wide range of SUVs.

Uptake, translocation, and elimination in sediment-rooted macrophytes: a model-supported analysis of whole sediment test data.

Understanding bioaccumulation in sediment-rooted macrophytes is crucial for the development of sediment toxicity tests using macrophytes. Here, we explore bioaccumulation in sediment-rooted macrophytes by tracking and modeling chemical flows of chlorpyrifos, linuron, and six PCBs in water-sediment-macrophyte systems. Chemical fluxes across the interfaces between pore water, overlying water, shoots, and roots were modeled using a novel multicompartment model. The modeling yielded the first mass-transfer parameter set reported for bioaccumulation by sediment-rooted macrophytes, with satisfactory narrow confidence limits for more than half of the estimated parameters. Exposure via the water column led to rapid uptake by Elodea canadensis and Myriophyllum spicatum shoots, followed by transport to the roots within 1-3 days, after which tissue concentrations gradually declined. Translocation played an important role in the exchange between shoots and roots. Exposure via spiked sediment led to gradual uptake by the roots, but subsequent transport to the shoots and overlying water remained limited for the chemicals studied. These contrasting patterns show that exposure is sensitive to test set up, chemical properties, and species traits. Although field-concentrations in water and sediment will differ from those in the tests, the model parameters can be assumed applicable for modeling exposure to macrophytes in the field.

Assessing joint line positions by means of the contralateral knee: a new approach for planning knee revision surgery?

Reconstructing the natural joint line in knee revision surgery improves clinical and functional outcome but may be challenging when both cartilage and bone were removed during previous operations. Assessing joint lines (JLs) by means of bony landmarks is inadvisable because of large variations in human anatomy. Because of the inherent symmetry of the human body, we hypothesised that JLs may be directly assessed by measuring the distances from the bony landmarks to the JL of the contralateral knee by means of radiographic images. Using scaled weight-bearing radiographs in anteroposterior view of both knees, two independent observers measured the distances from the fibular head, the medial and lateral epicondyle, and the adductor tubercle to the JL. A two-sided p value of ≤0.05 was considered statistically significant. Two hundred knees of 100 patients (50 men and 50 women) were examined. For the fibular head, the mean difference between the treated and the control knee was 0.0 mm with narrow confidence limits ranging from -1.1 to 1.1. As a new assessment method, we have suggested to assess the JL by means of radiographs of the contralateral knee. The most precise parameter was found to be the distance between the fibular head and the JL. The level of arthritis, age, gender, visibility of the landmarks, and misalignment did not influence measurement accuracy. This parameter is the first tibia-related landmark for assessing the JL, which advantageously corresponds to the tibia-first technique in revision surgery. Diagnostic Study, Level II.

Global Sea Surface Temperature Forecasts Using an Improved Multimodel Approach

Abstract With the availability of hindcasts or real-time forecasts from a number of coupled climate models, multimodel ensemble forecasting systems have gained popularity in recent years. However, many models share similar physics or modeling processes, which may lead to similar (or strongly correlated) forecasts. Assigning equal weights to each model in space and time may result in a biased forecast with narrower confidence limits than is appropriate. Although methods for combining forecasts that take into consideration differences in model accuracy over space and time exist, they suffer from a lack of consideration of the intermodel dependence that may exist. This study proposes an approach that considers the dependence among models while combining multimodel ensemble forecast. The approach is evaluated by combining sea surface temperature (SST) forecasts from five climate models for the period 1960–2005. The variable of interest, the monthly global sea surface temperature anomalies (SSTA) at a 5° × 5° latitude–longitude grid, is predicted three months in advance using the proposed algorithm. Results indicate that the proposed approach offers consistent and significant improvements for all the seasons over the majority of grid points compared to the case in which the dependence among the models is ignored. Consequently, the proposed approach of combining multiple models, taking into account the interdependence that exists, provides an attractive strategy to develop improved SST forecasts.

An Isolated Reduction of the FEV3/FVC Ratio Is an Indicator of Mild Lung Injury

The FEV3/FVC ratio is not discussed in the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines for lung function interpretation in spite of narrow confidence limits of normal and its association with smoking. We sought to determine whether a reduction in only the FEV3/FVC ratio was associated with physiologic changes compared with subjects with normal FEV1/FVC and FEV3/FVC ratios. Lung volumes and diffusion were studied in individuals with concomitant spirometry. Patients with restriction on total lung capacity (TLC) were excluded, as were repeat tests on the same patient. A total of 13,302 subjects were divided into three groups: (1) normal FEV1/FVC and FEV3/FVC (n = 7,937); (2) only a reduced FEV3/FVC (n = 840); and (3) reduced FEV1/FVC (n = 4,525). Subjects with only a reduced FEV3/FVC compared with those with normal FEV1/FVC and FEV3/FVC ratios had higher mean % predicted TLC (99.1% vs 97.1%, P &lt; .001), residual volume (RV) (109.4% vs 102.3%, P &lt; .001), and RV/TLC ratio (110.1% vs 105.4%, P &lt; .001). They had lower mean % predicted FEV1 (82.6% vs 90.2%, P &lt; .001), inspiratory capacity (94.5% vs 98.2%, P &lt; .001), and diffusing capacity of lung for carbon monoxide (Dlco) (78.3% vs 81.9%, P &lt; .001). Their mean BMI was lower (30.8 vs 31.5, P &lt; .005), they were older (61.2 vs 57.2, P &lt; .001), and more likely male (52.0% vs 40.4%, P &lt; .001), with no racial differences. Comparing this group to those with a reduced FEV1/FVC, similar but greater differences were noted in all of the previous measurements, though mean age and sex were not significantly different. The FEV3/FVC ratio should be routinely reported on spirometry. An isolated reduction may indicate an early injury pattern of hyperinflation, air trapping, and loss of Dlco.

An update of the statistical methods underlying the FELS method of skeletal maturity assessment

Background: Evaluation of skeletal maturity provides clinicians and researchers a window into the developmental progress of the skeleton. The FELS method for maturity assessment provides a point estimate and standard error based on 98 skeletal indicators.Aim: This paper outlines the statistical methodology used by the original FELS method and evaluates improvements that address the following: serial correlation in the calibration sample is now considered, a Bayesian estimation method is now employed to improve estimation near ages 0 and 18 years and uncertainty in the calibration due to sampling is now accounted for when computing confidence limits.Subjects and methods: The original FELS method was calibrated using 677 Fels Longitudinal Study participants. In the improved method, serial correlation is accounted for using GEE, a Bayesian analysis with a prior centred on chronological age is used and the bootstrap is used to account for all sources of variation.Results: Accounting for serial correlation resulted in larger slopes for ordinal indicators. The Bayesian paradigm led to narrower confidence limits and a natural interpretation of skeletal age. Sampling variability in the calibration parameters was negligible.Conclusion: Improvements to the statistical basis of the FELS method provide a more effective method of estimating skeletal maturity.

A global compilation of coral sea-level benchmarks: Implications and new challenges

I present a quality-controlled compilation of sea-level data from U–Th dated corals, encompassing 30 studies of 13 locations around the world. The compilation contains relative sea level (RSL) data from each location based on both conventional and open-system U–Th ages. I have applied a commonly used age quality control criterion based on the initial 234U/238U activity ratios of corals in order to select reliable ages and to reconstruct sea level histories for the last 150,000yr. This analysis reveals scatter of RSL estimates among coeval coral benchmarks both within individual locations and between locations, particularly during Marine Isotope Stage (MIS) 5a and the glacial inception following the last interglacial. The character of data scatter during these time intervals imply that uncertainties still exist regarding tectonics, glacio-isostacy, U-series dating, and/or coral position. To elucidate robust underlying patterns, with confidence limits, I performed a Monte Carlo-style statistical analysis of the compiled coral data considering appropriate age and sea-level uncertainties. By its nature, such an analysis has the tendency to smooth/obscure millennial-scale (and finer) details that may be important in individual datasets, and favour the major underlying patterns that are supported by all datasets. This statistical analysis is thus functional to illustrate major trends that are statistically robust (‘what we know’), trends that are suggested but still are supported by few data (‘what we might know, subject to addition of more supporting data and improved corrections’), and which patterns/data are clear outliers (‘unlikely to be realistic given the rest of the global data and possibly needing further adjustments’). Prior to the last glacial maximum and with the possible exception of the 130–120ka period, available coral data generally have insufficient temporal resolution and unexplained scatter, which hinders identification of a well-defined pattern with usefully narrow confidence limits. This analysis thus provides a framework that objectively identifies critical targets for new data collection, improved corrections, and integration of coral data with independent, stratigraphically continuous methods of sea-level reconstruction.

21st World Congress on Ultrasound in Obstetrics and Gynecology, 18-22 September 2011, Los Angeles, USA: presentations and awards

21st World Congress on Ultrasound in Obstetrics and Gynecology, 18-22 September 2011, Los Angeles, USA: presentations and awards

Sequential adjuvant chemotherapy and radiotherapy in endometrial cancer – Results from two randomised studies

Introduction Endometrial cancer patients with high grade tumours, deep myometrial invasion or advanced stage disease have a poor prognosis. Randomised studies have demonstrated the prevention of loco-regional relapses with radiotherapy (RT) with no effect on overall survival (OS). The possible additive effect of chemotherapy (CT) remains unclear. Two randomised clinical trials (NSGO-EC-9501/EORTC-55991 and MaNGO ILIADE-III) were undertaken to clarify if sequential combination of chemotherapy and radiotherapy improves progression-free survival (PFS) in high-risk endometrial cancer. The two studies were pooled. Methods Patients ( n = 540; 534 evaluable) with operated endometrial cancer International Federation of Obstetrics and Gynaecology (FIGO) stage I–III with no residual tumour and prognostic factors implying high-risk were randomly allocated to adjuvant radiotherapy with or without sequential chemotherapy. Results In the NSGO/EORTC study, the combined modality treatment was associated with 36% reduction in the risk for relapse or death (hazard ratio (HR) 0.64, 95% confidence interval (CI) 0.41–0.99; P = 0.04); two-sided tests were used. The result from the Gynaecologic Oncology group at the Mario Negri Institute (MaNGO)-study pointed in the same direction (HR 0.61), but was not significant. In the combined analysis, the estimate of risk for relapse or death was similar but with narrower confidence limits (HR 0.63, CI 0.44–0.89; P = 0.009). Neither study showed significant differences in the overall survival. In the combined analysis, overall survival approached statistical significance (HR 0.69, CI 0.46–1.03; P = 0.07) and cancer-specific survival (CSS) was significant (HR 0.55, CI 0.35–0.88; P = 0.01). Conclusion Addition of adjuvant chemotherapy to radiation improves progression-free survival in operated endometrial cancer patients with no residual tumour and a high-risk profile. A remaining question for future studies is if addition of radiotherapy to chemotherapy improves the results.

A new method for detecting and interpreting biodiversity and ecological community thresholds

Summary 1. Existing methods for identifying ecological community thresholds are designed for univariate indicators or multivariate dimension-reduction of community structure. Most are insensitive to responses of individual taxa with low occurrence frequencies or highly variable abundances, properties of the vast majority of taxa in community data sets. We introduce Threshold Indicator Taxa ANalysis (TITAN) to detect changes in taxa distributions along an environmental gradient over space or time, and assess synchrony among taxa change points as evidence for community thresholds. 2. TITAN uses indicator species scores to integrate occurrence, abundance and directionality of taxa responses. It identifies the optimum value of a continuous variable, x, that partitions sample units while maximizing taxon-specific scores. Indicator z scores standardize original scores relative to the mean and SD of permuted samples along x, thereby emphasizing the relative magnitude of change and increasing the contributions of taxa with low occurrence frequencies but high sensitivity to the gradient. TITAN distinguishes negative (z−) and positive (z+) taxa responses and tracks cumulative responses of declining [sum(z−)] and increasing [sum(z+)] taxa in the community. Bootstrapping is used to estimate indicator reliability and purity as well as uncertainty around the location of individual taxa and community change points. 3. Using two simulated data sets, TITAN correctly identified taxon and community thresholds in more than 99% of 500 unique versions of each simulation. In contrast, multivariate change-point analysis did not distinguish directional taxa responses, resulting in much wider confidence intervals that in one instance failed to capture thresholds in 38% of the iterations. 4. Retrospective analysis of macroinvertebrate community response to a phosphorus gradient supported previous threshold estimates, although TITAN produced narrower confidence limits and revealed that several taxa declined at lower levels of phosphorus. Re-analysis of macroinvertebrate responses to an urbanization gradient illustrated disparate change points for declining (0·81–3·3% urban land) and increasing (6·8–26·6%) taxa, whereas the published threshold estimate (20–30%) missed the declining-taxa threshold because it could not distinguish their synchronous decline from the gradual increase in ubiquitous taxa. 5.Synthesis and applications. By deconstructing communities to assess synchrony of taxon-specific change points, TITAN provides a sensitive and precise alternative to existing methods for assessing community thresholds. TITAN has tremendous potential to inform conservation of rare or threatened species, develop species sensitivity models, identify reference conditions and to support development of numerical regulatory criteria.

Rhinite, conjonctivite et asthme

The FEV3/FVC ratio is not discussed in the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines for lung function interpretation in spite of narrow confidence limits of normal and its association with smoking. We sought to determine whether a reduction in only the FEV3/FVC ratio was associated with physiologic changes compared with subjects with normal FEV1/FVC and FEV3/FVC ratios.Lung volumes and diffusion were studied in individuals with concomitant spirometry. Patients with restriction on total lung capacity (TLC) were excluded, as were repeat tests on the same patient. A total of 13,302 subjects were divided into three groups: (1) normal FEV1/FVC and FEV3/FVC (n = 7,937); (2) only a reduced FEV3/FVC (n = 840); and (3) reduced FEV1/FVC (n = 4,525).Subjects with only a reduced FEV3/FVC compared with those with normal FEV1/FVC and FEV3/FVC ratios had higher mean % predicted TLC (99.1% vs 97.1%, P < .001), residual volume (RV) (109.4% vs 102.3%, P < .001), and RV/TLC ratio (110.1% vs 105.4%, P < .001). They had lower mean % predicted FEV1 (82.6% vs 90.2%, P < .001), inspiratory capacity (94.5% vs 98.2%, P < .001), and diffusing capacity of lung for carbon monoxide (Dlco) (78.3% vs 81.9%, P < .001). Their mean BMI was lower (30.8 vs 31.5, P < .005), they were older (61.2 vs 57.2, P < .001), and more likely male (52.0% vs 40.4%, P < .001), with no racial differences. Comparing this group to those with a reduced FEV1/FVC, similar but greater differences were noted in all of the previous measurements, though mean age and sex were not significantly different.The FEV3/FVC ratio should be routinely reported on spirometry. An isolated reduction may indicate an early injury pattern of hyperinflation, air trapping, and loss of Dlco.

Data assimilation and uncertainty analysis of environmental assessment problems—an application of Stochastic Transfer Function and Generalised Likelihood Uncertainty Estimation techniques

Abstract Stochastic Transfer Function (STF) and Generalised Likelihood Uncertainty Estimation (GLUE) techniques are outlined and applied to an environmental problem concerned with marine dose assessment. The goal of both methods in this application is the estimation and prediction of the environmental variables, together with their associated probability distributions. In particular, they are used to estimate the amount of radionuclides transferred to marine biota from a given source: the British Nuclear Fuel Ltd (BNFL) repository plant in Sellafield, UK. The complexity of the processes involved, together with the large dispersion and scarcity of observations regarding radionuclide concentrations in the marine environment, require efficient data assimilation techniques. In this regard, the basic STF methods search for identifiable, linear model structures that capture the maximum amount of information contained in the data with a minimal parameterisation. They can be extended for on-line use, based on recursively updated Bayesian estimation and, although applicable to only constant or time-variable parameter (non-stationary) linear systems in the form used in this paper, they have the potential for application to non-linear systems using recently developed State Dependent Parameter (SDP) non-linear STF models. The GLUE based-methods, on the other hand, formulate the problem of estimation using a more general Bayesian approach, usually without prior statistical identification of the model structure. As a result, they are applicable to almost any linear or non-linear stochastic model, although they are much less efficient both computationally and in their use of the information contained in the observations. As expected in this particular environmental application, it is shown that the STF methods give much narrower confidence limits for the estimates due to their more efficient use of the information contained in the data. Exploiting Monte Carlo Simulation (MCS) analysis, the GLUE technique is used to estimate how the errors involved in the STF model structure and observations influence the model outputs and errors. The discussion on updating information originating from different locations using GLUE procedure is also given. A final aim of the paper is to use the results obtained in this particular example to explore the differences between the GLUE and STF approaches.

Stimulus size and the variability of the threshold response in the central and peripheral visual field

Purpose: The investigation of the peripheral visual field has shown considerable interest for the investigation of field loss attributed to anticonvulsant therapy. The purpose was to determine the within‐visit between‐subject, the between‐visit between‐subject, and the between‐location variability of the threshold response in the normal eye with increase in stimulus eccentricity out to 60° as a function of stimulus size.Methods: Forty‐eight normal subjects attended for a total of three visits (mean age = 49.5 years, SD = 18.9, range 22–84 years). At the first visit, one randomly assigned eye of each subject was examined with the Humphrey Field Analyzer 750 (Carl Zeiss, Jena, Germany) and the Full Threshold algorithm using Programs 30–2 and 60–4 and stimulus sizes III and V. The combination of stimulus size and of program, and the order of the combination within‐ and between‐sessions, were randomized for each subject. The results of the first visit were considered as a familiarization period and were discarded. The protocol at the second and third visits was identical to that at the first visit for each subject.Results: The ratio of the SD of the group mean sensitivity was determined at each stimulus location for stimulus size III compared with stimulus size V for Programs 30–2 and 60–4 at visit 3. The SDs were greater than unity for Program 30–2 (p &lt; 0.0001) and for Program 60–4 (p &lt; 0.0001) indicating greater variability for the size III stimulus. The SDs were also greater than unity for the central inner zone (p &lt; 0.0001), central outer zone (p &lt; 0.0001) and peripheral inner zone (p &lt; 0.0001). The ratios in the peripheral outer zone were not quite greater than unity (p = 0.054). The ratios increased with increase in eccentricity by up to 2.7 times between 15° and 30° eccentricity and by up to 2.7 times between 30° and 60° eccentricity. The group mean ratio did not vary significantly between the two visits for Program 30–2 stimulus size III (p = 0.563), Program 60–4 stimulus size III (p = 0.935) and for Program 60–4 stimulus size V (p = 0.005). However, the group mean SD was lower at visit 3 compared with visit 2 for Program 30–2 stimulus size V (p = 0.0004). The SDs associated with the extreme peripheral locations in the superior and nasal fields were smaller for stimulus size III because the threshold was frequently attenuated by lid and facial contour.Conclusions: Considerably narrower confidence limits for normality for the peripheral regions of Program 30–2 and for 60–4 are demonstrated with the use of Goldmann size V.