Random Measurement Error Research Articles

Reproducibility and validity of diet quality scores derived from food-frequency questionnaires

Diet quality scores (DQSs) are frequently used to study diet-disease relations but the validity of these scores derived from FFQs has rarely been evaluated. To evaluate the validity and reproducibility of 6 commonly used DQSs derived from the FFQ, including the Alternate Healthy Eating Index-2010, Dietary Approaches to Stop Hypertension Trial score, alternative Mediterranean diet score, and 3 plant-based diet indices (overall, healthful, and unhealthful). This analysis included 1394 participants from the Men's Lifestyle Validation Study (N = 652) and the Women's Lifestyle Validation Study (N = 742). Participants completed a 152-item FFQ at the beginning of the study and 1 y later, as well as completed 2 weighed 7-d dietary records (7DDRs) and donated 2 blood samples 6 mo apart between FFQ assessments. The reproducibility of the FFQs was evaluated by rank intraclass correlation coefficients (ICCs). The validity was assessed by comparing FFQ-derived DQSs with those from the average of two 7DDRs using Spearman rank correlation coefficients deattenuated for random measurement error in the 7DDRs (rs). Furthermore, we calculated the correlations between DQSs and plasma biomarkers of diet, including fatty acids, folate, carotenoids, retinol, and α- and γ-tocopherol. Six FFQ-derived DQSs demonstrated moderate to high reproducibility (energy-adjusted ICCs: 0.61-0.84) and validity (energy-adjusted, deattenuated rs = 0.56-0.80) in both men and women. We consistently observed expected correlations between FFQ-derived DQSs with plasma fatty acids, including long-chain n-3 (ω-3) and trans fatty acids, most carotenoids, and γ-tocopherol (rs > 0.2). Our study demonstrates the validity of the FFQ to evaluate overall diet quality using 6 commonly used DQSs. In addition, these DQSs have qualitatively demonstrated biological relevance, as indicated by their correlations with circulating biomarkers.

Consistency and Reliability Analyses of a Comprehensive Index for the Evaluation of Teeth Alignment Performance.

(1) Introduction: The purpose of this work was to describe a method and propose a novel accuracy index to assess orthodontic alignment performance. (2) Methods: Fifteen patients who underwent orthodontic treatment using directly printed clear aligners were recruited. The study sample included 12 maxillary and 10 mandibular arches, whose pre-treatment, predicted and post-treatment digital models were superimposed on the untreated posterior teeth by means of a best-fit surface-based registration, which was also used to transfer three anatomical landmarks, digitally labeled on the crown of each anterior moving tooth, from the pre-treatment to the predicted and post-treatment models. The Teeth Alignment Performance (TAP) index, quantifying how close the final landmarks were to their expected final position, was proposed as an accuracy index of both individual tooth and group of teeth movement, and its inter-examiner repeatability was tested. (3) Results: No systematic inter-rater discrepancy associated with TAP was observed (p > 0.05), not even when a slight systematic inter-rater difference in landmark labelling was detected (for the upper central incisors, p < 0.001). In addition, all Intra-class Correlation Coefficient (ICC) values showed excellent inter-rater agreement (>0.95), and the small Random Error of Measurement (REM), ranging from 1% for the arch TAP to 3% for the lower canine TAP, indicated that this accuracy index is highly repeatable. (4) Conclusions: The TAP index was proven to be comprehensive, consistent and reliable in assessing the performance of teeth alignment according to a digital plan. The proposed method is also suitable to be implemented in the clinical digital workflow.

Potential impact of systematic and random errors in blood pressure measurement on the prevalence of high office blood pressure in the United States.

The authors examined the proportion of US adults that would have their high blood pressure (BP) status changed if systolic BP (SBP) and diastolic BP (DBP) were measured with systematic bias and/or random error versus following a standardized protocol. Data from the 2017–2018 National Health and Nutrition Examination Survey (NHANES; n = 5176) were analyzed. BP was measured up to three times using a mercury sphygmomanometer by a trained physician following a standardized protocol and averaged. High BP was defined as SBP ≥130 mm Hg or DBP ≥80 mm Hg. Among US adults not taking antihypertensive medication, 32.0% (95%CI: 29.6%,34.4%) had high BP. If SBP and DBP were measured with systematic bias, 5 mm Hg for SBP and 3.5 mm Hg for DBP higher and lower than in NHANES, the proportion with high BP was estimated to be 44.4% (95%CI: 42.6%,46.2%) and 21.9% (95%CI 19.5%,24.4%). Among US adults taking antihypertensive medication, 60.6% (95%CI: 57.2%,63.9%) had high BP. If SBP and DBP were measured 5 and 3.5 mm Hg higher and lower than in NHANES, the proportion with high BP was estimated to be 71.8% (95%CI: 68.3%,75.0%) and 48.4% (95%CI: 44.6%,52.2%), respectively. If BP was measured with random error, with standard deviations of 15 mm Hg for SBP and 7 mm Hg for DBP, 21.4% (95%CI: 19.8%,23.0%) of US adults not taking antihypertensive medication and 20.5% (95%CI: 17.7%,23.3%) taking antihypertensive medication had their high BP status re‐categorized. In conclusions, measuring BP with systematic or random errors may result in the misclassification of high BP for a substantial proportion of US adults.

Distinct characteristics of correlation analysis at the single-cell and the population level.

Correlation analysis is widely used in biological studies to infer molecular relationships within biological networks. Recently, single-cell analysis has drawn tremendous interests, for its ability to obtain high-resolution molecular phenotypes. It turns out that there is little overlap of co-expressed genes identified in single-cell level investigations with that of population level investigations. However, the nature of the relationship of correlations between single-cell and population levels remains unclear. In this manuscript, we aimed to unveil the origin of the differences between the correlation coefficients at the single-cell level and that at the population level, and bridge the gap between them. Through developing formulations to link correlations at the single-cell and the population level, we illustrated that aggregated correlations could be stronger, weaker or equal to the corresponding individual correlations, depending on the variations and the correlations within the population. When the correlation within the population is weaker than the individual correlation, the aggregated correlation is stronger than the corresponding individual correlation. Besides, our data indicated that aggregated correlation is more likely to be stronger than the corresponding individual correlation, and it was rare to find gene-pairs exclusively strongly correlated at the single-cell level. Through a bottom-up approach to model interactions between molecules in a signaling cascade or a multi-regulator-controlled gene expression, we surprisingly found that the existence of interaction between two components could not be excluded simply based on their low correlation coefficients, suggesting a reconsideration of connectivity within biological networks which was derived solely from correlation analysis. We also investigated the impact of technical random measurement errors on the correlation coefficients for the single-cell level and the population level. The results indicate that the aggregated correlation is relatively robust and less affected. Because of the heterogeneity among single cells, correlation coefficients calculated based on data of the single-cell level might be different from that of the population level. Depending on the specific question we are asking, proper sampling and normalization procedure should be done before we draw any conclusions.

Error Analysis for Repeatability Enhancement of a Dual-Rotation Mueller Matrix Ellipsometer

Since the Mueller matrix ellipsometer has been used as a highly accurate tool for thin film measurement, the error analysis and repeatability enhancement of such a tool are of great importance. The existence of the Poisson–Gaussian mixed noise and the random bias of the trigger signal in the optical measurement system may reduce the repeatability and accuracy of a measurement. Utilizing the probabilistic analysis, the random errors in the Mueller matrix measurements are quantified. A quantitative analysis on the instrument matrix has been carried out to assess the individual effects for different error sources. We proposed a general optimal instrument matrix which is capable of minimizing the estimation variance for both Gaussian additive noise and Poisson shot noise. Besides, a peak-matching algorithm is proposed to compress the repeatability errors due to the bias of the trigger signal and the limited sampling frequency. The effectiveness of the proposed methods is shown using both virtual simulations and experiments carried out on our self-developed instrument, which potentially paves a way to reduce the requirements on motor performance, acquisition card resolution, and trigger accuracy, which are critical to cost reduction.

Comparison of differences and random errors in pedicle diameter measurements between MRI and CT: observational study of 315 pedicles in Lenke type 1 adolescent idiopathic scoliosis patients

BACKGROUND CONTEXTPosterior spinal fusion with pedicle screws is commonly used for the treatment of adolescent idiopathic scoliosis (AIS). To reduce radiation exposure, methods other than computed tomography (CT) are desirable for preoperative determination of pedicle diameter. PURPOSEInvestigate the differences between magnetic resonance imaging (MRI) and CT measurements of pedicle diameter. STUDY DESIGNCross-sectional research. PATIENT SAMPLETwenty-one AIS Lenke type 1 patients (19 female and 2 males, mean age at surgery: 15.4 years) who underwent posterior spinal fusion between April 2009 and October 2019. OUTCOME MEASURESGap between CT and MRI pedicle diameters. METHODSThe inner and outer diameters of the right and left pedicles from T1 to L3 were measured separately by two spine surgeons for statistical comparisons. RESULTSThe respective minimum and maximum CT-MRI values were -3.7 mm and 4.7 mm for inner diameter and -4.6 mm and 5.3 mm for outer diameter. Regarding inter-examiner error, the probability of a 2 mm difference in measurement was less than 5% for both modalities. The probability of a 1 mm difference was also less than 5%, and that of a 3 mm or more difference was 2.1% for the inner diameter and 2.9% for the outer diameter. Whereas low body weight was significantly associated with measurement differences, pedicle laterality was not. CONCLUSIONSMRI does not have the reliability to measure pedicle size in AIS patients at present. However, with advancements in image processing technology, the accuracy of pedicle size measurement by MRI may soon improve.

A new gamma degradation process with random effect and state-dependent measurement error

In this paper, a new gamma-based degradation process with random effect is proposed that allows to account for the presence of measurement error that depends in stochastic sense on the measured degradation level. This new model extends a perturbed gamma model recently suggested in the literature, by allowing for the presence of a unit to unit variability. As the original one, the extended model is not mathematically tractable. The main features of the proposed model are illustrated. Maximum likelihood estimation of its parameters from perturbed degradation measurements is addressed. The likelihood function is formulated. Hence, a new maximization procedure that combines a particle filter and an expectation-maximization algorithm is suggested that allows to overcome the numerical issues posed by its direct maximization. Moreover, a simple algorithm based on the same particle filter method is also described that allows to compute the cumulative distribution function of the remaining useful life and the conditional probability density function of the hidden degradation level, given the past noisy measurements. Finally, two numerical applications are developed where the model parameters are estimated from two sets of perturbed degradation measurements of carbon-film resistors and fuel cell membranes. In the first example the presence of random effect is statistically significant while in the second example it is not significant. In the applications, the presence of random effect is checked via appropriate statistical procedures. In both the examples, the influence of accounting for the presence of random effect on the estimates of the cumulative distribution function of the remaining useful life of the considered units is also discussed. Obtained results demonstrate the affordability of the proposed approach and the usefulness of the proposed model.

The EU self-surplus puzzle: an indication of VAT fraud?

The world runs a trade surplus with itself: the reported values of exports exceed the reported values of imports. This is logically impossible but a well-known empirical fact. Less well-known is the fact that, in recent years, the EU has a trade surplus with itself that amounts to more than 80% of the global surplus. In this paper, we show that this EU self-surplus is worth a striking 307 billion Euro in 2018, equaling 1.9% of the Union’s GDP, which persists both in goods and services trade accounts. We further examine discrepancies in goods and services trade accounts at the country and country pair level. These are strongest between neighboring countries and exist for members of the Euro Area as well as non-members. Around the 2004 Eastern Enlargement, the EU self-surplus quadrupled. Our estimations suggest that Cyprus, Ireland, Luxembourg, and Sweden are EU Members with the most inaccurate statistical regimes. We observe systematic biases which unlikely root in random measurement error. By contrast, we suspect that a large fraction of the EU’s self-surplus puzzle seems related to fraud in value added tax (VAT). VAT exemptions for exporters provide strong incentives for the over-declaration of true export values. The resulting loss in tax income could amount to as much as 64 billion Euro per year.

A meta-analysis of diagnostic test performance of peripheral arterial tonometry studies.

The objective of this meta-analysis was to analyze agreement in apnea-hypopnea index (AHI) determination between peripheral arterial tonometry (PAT) and polysomnography (PSG) studies. Mean AHI bias and standard deviation extracted from Bland-Altman plots reported in studies were pooled in a meta-analysis, which was then used to calculate percentage errors of limit agreement in AHI determination by PAT using PSG AHI as the reference. Individual participant data (where reported in studies) were used to compute Cohen's kappa to assess agreement between PSG and PAT on sleep apnea severity and for computing the sensitivity and specificity of PAT at different AHI thresholds using PSG AHI as the reference. From 17 studies and 1,318 participants (all underwent simultaneous PSG and use of the WatchPAT device), a pooled mean AHI bias of 0.30 (standard error [SE], 0.74) and a WatchPAT AHI percentage error of 230% was calculated. The meta-analysis of Cohen's kappa for agreement between PSG and WatchPAT studies for classifying patients with no sleep apnea, mild, moderate, or severe sleep apnea severity was 0.45 (SE, 0.06), 0.29 (SE, 0.05), 0.25 (SE, 0.07), and 0.64 (SE, 0.05), respectively. At AHI thresholds of 5, 15 and 30 events/h, WatchPAT studies showed pooled sensitivities and specificities of 94.11% and 43.47%, 92.21% and 72.39%, and 74.11% and 87.10%, respectively. Likelihood ratios were not significant at any AHI threshold. The results of this meta-analysis suggest clinically significant discordance between WatchPAT and PSG measurements of AHI, significant sleep apnea severity misclassification by PAT studies, and poor diagnostic test performance. Iftikhar IH, Finch CE, Shah AS, Augunstein CA, Ioachimescu OC. A meta-analysis of diagnostic test performance of peripheral arterial tonometry studies. J Clin Sleep Med. 2022;18(4):1093-1102.

Mixture model analysis of Transition Edge Sensor pulse height spectra.

To calibrate an optical transition edge sensor (TES), for each pulse of the light source (e.g. pulsed laser), one must determine the ratio of the expected number of photons that deposit energy and the expected number of photons created by the laser. Based on the estimated pulse height generated by each energy deposit, we form a pulse height spectrum with features corresponding to different numbers of deposited photons. We model the number of photons that deposit energy per laser pulse as a realization of a Poisson process, and the observed pulse height spectrum with a mixture model method. For each candidate feature set, we determine the expected number of photons that deposit energy per pulse and its associated uncertainty based on the mixture model weights corresponding to that candidate feature set. From training data, we select the optimal feature set according to an uncertainty minimization criterion. We then determine the expected number of photons that deposit energy per pulse and its associated uncertainty for test data that is independent of the training data. Our uncertainty budget accounts for random measurement errors, systematic effects due to mismodeling feature shapes in our mixture model, and possible imperfections in our feature set selection method.

DETERMINATION OF THE COMPRESSION STRENGTH RP OF MULTILAYER PLATES MADE OF SLAGOSITALS

The methodology of creating multifunctional acoustic automated devices has been further developed, it is based on the construction of simple algorithms for transforming and processing signals of measuring instruments. A differential acoustic method for controlling the physical and mechanical parameters of multilayer plates made of slag glass-ceramics has been investigated. A structural diagram of an automated device for measuring acoustic control of the ultimate compressive strength Rр of a controlled slag glass-ceramics plate is proposed. The option of automation of the measurement process considered in the article makes it possible to carry out measuring control of the strength characteristics for a relatively short period of time and by averaging the results of measurements of the physical and mechanical parameters of slag glass-ceramic plates, leads to a decrease in the values of random measurement errors and thereby contributes to an increase in the accuracy of measurements of physical and mechanical parameters of slag glass-ceramics products. The values of the relative increments of the attenuation coefficient ∆ƞ23/ƞ4were obtained, while the ranges of the values of the attenuation coefficient of a transmission of various waveforms of the piezoelectric transducer correspond to the ranges of the compressive strength Rр of the test sample. At the same time, the control of the strength of the material Rр at multiple frequencies is due to the fact that even a slight change in the geometric parameters of the slag glass-ceramics slab leads to a change in the generalized parameters of the universal transformation functions of the measuring differential acoustic devices, which are associated with the physical and mechanical characteristics of the controlled material of the sample The proposed two-parameter differential acoustic control method allows to keep in mind the linkage between temperature and mechanical parameters: the unequal distribution of the temperature along the length of the sample and the uneven distribution deformation of temperature with the localization of this plastic component in the middle part of the slag glass-ceramics plate, which is most significantly affected by temperature and, as a consequence, is subject to gradual destruction.

Analysis of the error distribution density convergence with its orthogonal decomposition in navigation measurements

Modern trends towards the expansion of online services lead to the need to determine the location of customers, who may also be on a moving object (vessel or aircraft, others vehicle – hereinafter the “Vehicle”). This task is of particular relevance in the fields of medicine – when organizing video conferencing for diagnosis and/or remote rehabilitation, e.g., for post-infarction and post-stroke patients using wireless devices, in education – when organizing distance learning and when taking exams online, etc. For the analysis of statistical materials of the accuracy of determining the location of a moving object, the Gaussian normal distribution is usually used. However, if the histogram of the sample has “heavier tails”, the determination of latitude and longitude’s error according to Gaussian function is not correct and requires an alternative approach. To describe the random errors of navigation measurements, mixed laws of a probability distribution of two types can be used: the first type is the generalized Cauchy distribution, the second type is the Pearson distribution, type VII. This paper has shown that it’s possible obtaining the decomposition of the error distribution density using orthogonal Hermite polynomials, without having its analytical expression. Our numerical results show that the approximation of the distribution function using the Gram-Charlier series of type A makes it possible to apply the orthogonal decomposition to describe the density of errors in navigation measurements. To compare the curves of density and its orthogonal decomposition, the density values were calculated. The research results showed that the normalized density and its orthogonal decomposition practically coincide.

Correction of residence time distributions and hydraulic indexes affected by tracer release duration in surface flow constructed wetlands

In tracer experiments of surface flow constructed wetlands, residence time distributions (RTDs) are generally originated from the normalized concentration data of recovered tracers based on ideal instantaneous tracer release mode. However, this tracer release mode is commonly approximated by finite-continuous tracer release over a relatively short duration. As a result, the accuracy of RTDs and hydraulic indexes cannot be guaranteed if the RTD data and index values were still calculated based on the instantaneous release. To solve this problem, a method for correcting the original RTD data and the index values affected by tracer release duration was proposed. The correction of hydraulic indexes can be performed using analytical formulas, whereas the correction of the RTDs requires an RTD model (such as the gamma distribution and one-dimensional advection-dispersion model) or a smoothing algorithm (such as the simple moving average algorithm) to avoid the increasing effect of random measurement errors caused by the direct use of the RTD correction formulas. The correction method was successfully verified by a specially designed tracer test, and its practical application effect was exemplified. A Monte Carlo test also proved that the RTD correction owed certain robustness to tracer release instability, while the correction of some hydraulic indexes that reflect flow dispersion and comprehensive hydraulic efficiency had inferior robustness. Aside from this, the influence of tracer release duration on RTDs and hydraulic indexes without any correction was analyzed. It was found that the release duration caused the shape of the original RTDs to be more skewed in the positive direction of the x-axis and changed from “thin and high” to “fat and short”, while the duration of the release caused the positive relative errors of most indexes, which became more serious with an increase in the duration or worsening hydraulic performance. Based on these influence rules, 0.01 was defined as the threshold of the normalized release duration which needs to correct RTDs and hydraulic indexes, considering that the relative errors between the uncorrected and corrected indexes were less than 5% when the normalized duration was less than this threshold.

Sensitivity analysis for random measurement error using regression calibration and simulation-extrapolation.

Sensitivity analysis for random measurement error can be applied in the absence of validation data by means of regression calibration and simulation-extrapolation. These have not been compared for this purpose. A simulation study was conducted comparing the performance of regression calibration and simulation-extrapolation for linear and logistic regression. The performance of the two methods was evaluated in terms of bias, mean squared error (MSE) and confidence interval coverage, for various values of reliability of the error-prone measurement (0.05-0.91), sample size (125-4000), number of replicates (2-10), and R-squared (0.03-0.75). It was assumed that no validation data were available about the error-free measures, while correct information about the measurement error variance was available. Regression calibration was unbiased while simulation-extrapolation was biased: median bias was 0.8% (interquartile range (IQR): -0.6;1.7%), and -19.0% (IQR: -46.4;-12.4%), respectively. A small gain in efficiency was observed for simulation-extrapolation (median MSE: 0.005, IQR: 0.004;0.006) versus regression calibration (median MSE: 0.006, IQR: 0.005;0.009). Confidence interval coverage was at the nominal level of 95% for regression calibration, and smaller than 95% for simulation-extrapolation (median coverage: 85%, IQR: 73;93%). The application of regression calibration and simulation-extrapolation for a sensitivity analysis was illustrated using an example of blood pressure and kidney function. Our results support the use of regression calibration over simulation-extrapolation for sensitivity analysis for random measurement error.

Test-retest Reliability of the Korean Matrix Sentence-in-noise Recognition in Sound-field Testing Condition

Purpose: This study aimed to measure the test-retest reliability of the Korean Matrix sentence-in-noise test in a sound-field testing condition.Methods: Fifty-five listeners with normal hearing participated. The sound-field speech-in-noise test was administered with a front loudspeaker by presenting noise at a fixed level (65 dB SPL) while adaptively adjusting the sentence level based on the listener’s response. The speech reception thresholds (SRTs) corresponding to 50% sentence-in-noise intelligibility were obtained using speech-shaped noise (SSN), International Collegium of Rehabilitative Audiology (ICRA) noise, and International Speech Test Signal (ISTS) noise. For the test-retest reliability, each subject was tested twice in a 2-week interval. The test-retest reliabilities were judged by the intraclass correlation coefficient (ICC), the minimal detectable change (MDC) values, and Bland-Altman plots.Results: The test-retest reliabilities of the Korean Matrix sentence test were good (ICC, 0.84~0.86) across SSN, ICRA, ISTS noises. The MDC was 0.92 dB SNR for SSN and 2.83 and 2.98 dB SNR for ICRA and ISTS, indicating the random measurement error varied across the types of noise.Conclusion: The Korean Matrix sentence-in-noise test can be used as a reliable tool to assess speech-in-noise intelligibility in sound-field testing condition. Further study across various sessions would strengthen the present finding.

Revisiting nutrition\u2013labor productivity link: new empirical evidence from farm households in Ethiopia

BackgroundAmong others, the productive use of surplus labor is a viable mechanism to transform the agricultural sector and thus the whole economy in low-income countries. It is critically important to understand the factors that condition labor productivity to design and deploy effective agricultural and labor market policies. A few studies confirm that, at low-income levels, improving nutrition can contribute to the labor productivity of households. These studies rely heavily on self-reported farm data, which are prone to systematic and random measurement errors. The empirical evidence on this topic remains inadequate and inconclusive for this reason. Here, we substantiate whether better nutritional status enhances the labor productivity of farm households using objective measures of plot-level data from a recent household survey in Ethiopia. We also employ alternative measures of nutrition status indicators known as, Food Consumption Score (FCS) and Household Dietary Diversity Score (HDDS), inter alia, to capture additional aspects of nutrition such as diet quality and diversity, which are overlooked by calorie intake data. To deal with possible endogeneity, we employ a panel fixed effect estimation technique with a rich set of household socioeconomic and plot characteristics.ResultsWe observe that the impact of current nutritional status, as measured by HDDS, on labor productivity varies considerably depending on the initial level of diet quality and diversity with a stronger and positive effect for low-consumption households. In an alternative specification, we also observe a positive farm labor productivity effect of current nutritional status as measured by FCS with a homogenous effect across households. However, the effect of the outcome of past nutritional status as evaluated by the Activity of Daily Living Index (ADLI) seems negligible.ConclusionOur findings indicate that improving nutrition can contribute to farm labor productivity at least for households with low current diet quality and diversity. Also, based on the findings, we conclude that there is a possibility of a low consumption–low productivity trap in Ethiopia.

Minimal detectable change of the disc‐fovea angle for ocular torsion assessment

AbstractPurposeThe disc‐fovea angle (DFA) is used as a relevant indicator of ocular torsion change in cyclovertical strabismus. However, interpretation of the variation in time must differentiate whether a real change has occurred or if the disparity is due to random measurement error. The aim of the study was to obtain the minimal detectable change (MDC) of the DFA. It represents the minimal variation between two measurements that may be considered a real ocular torsion change.MethodsA prospective cross‐sectional study was conducted in San Carlos Clinical Hospital of Madrid, Spain. Sixty healthy right eyes from 60 patients (31 men and 29 women) were recruited. Three digital fundus photographs were obtained, and between measurements, the patient moved their head away from the head support and then returned. Two observers quantified the DFA with software designed with MATLAB. Test‐retest and interrater reliability were calculated.ResultsMean participant age was 56.1 years (SD 16.6, range 25–85). Mean DFA was 8.1° (SD 3.5, range 1.3–18.5). Test‐retest reliability for Observer 1 (Ob1), Observer 2 (Ob2) and interrater reliability were excellent (ICC 0.80, 0.83 and 0.95, respectively). Precision was 2.9° (Ob1) and 3.0° (Ob2), and the MDC95 was 4.1° (Ob1) and 4.2° (Ob2). Bland‐Altman analysis revealed an absence of bias and a homoscedastic distribution of the differences.ConclusionsThe MDC of the DFA in fundus photography was 4°, which represents the minimal change that may be considered a real change in ocular torsion. This result may improve the interpretation of ocular torsion changes in surgery and clinical scenarios.

Examining interindividual differences in select muscle and whole-body adaptations to continuous endurance training.

What is the central question of the study? Do interindividual differences in trainability exist for morphological and molecular skeletal muscle responses to aerobic exercise training? What is the main finding and its importance? Interindividual differences in trainability were present for some, but not all, morphological and molecular outcomes included in our study. Our findings suggest that it is inappropriate, and perhaps erroneous, to assume that variability in observed responses reflects interindividual differences in trainability in skeletal muscle responses to aerobic exercise training. Studies have interpreted a wide range of morphological and molecular changes in human skeletal muscle as evidence of interindividual differences in trainability. However, these interpretations fail to account for the influence of random measurement error and within-subject variability. The purpose of the present study was to use the standard deviation of individual response (SDIR ) statistic to test the hypothesis that interindividual differences in trainability are present for some but not all skeletal muscle outcomes. Twenty-nine recreationally active males (age: 21±2years; BMI: 24±3kg/m2 ; ; 45±7ml/kg/min) completed 4weeks of continuous training (REL; n=14) or control (n=15). Maximal enzyme activities (citrate synthase and β-hydroxyacyl-CoA dehydrogenase), capillary density, fibre type composition, fibre-specific succinate dehydrogenase activity and substrate storage (intramuscular triglycerides and glycogen), and markers of mitophagy (BCL2-interacting protein 3 (BNIP3), BNIP3-like protein, parkin and PTEN-induced kinase 1) were measured in vastus lateralis samples collected before and after the intervention. We also calculated SDIR values for , peak work rate and the onset of blood lactate accumulation for the REL group and a separate group that exercised at the negative talk test stage. Although positive SDIR values - indicating interindividual differences in trainability - were obtained for aerobic capacity outcomes, maximal enzyme activities, capillary density, all fibre-specific outcomes and BNIP3 protein content, the remaining outcomes produced negative SDIR values indicating a large degree of random measurement error and/or within-subject variability. Our findings question the interpretation of heterogeneity in observed responses as evidence of interindividual differences in trainability and highlight the importance of including control groups when analysing individual skeletal muscle response to exercise training.

Determination of Wind Velocity Projections Taking into Account Measurements of Airspeed, Angles of Attack and Sideslip

The paper deals with the problem of estimating the projections of the wind velocity in flight. The proposed method allows to obtain estimates for three projections of wind speed in the normal Earth coordinate system using data from the satellite navigation system, as well as on-board aerometric measurements of airspeed, angles of attack and glide. The main idea underlying the method is that satellite measurements of three aircraft velocity projections relative to the Earth’s coordinate system are very accurate (errors usually do not exceed 0.2 m/s). This makes it possible to use satellite velocity measurements as a kind of reference, just as in practical metrology, in order to assess the errors of measurement tools, they are compared with a standard, that is, a significantly more accurate measurement tool. In order to implement this approach not in a metrological laboratory, but on board an aircraft, it is proposed to use the relationships known from the flight dynamics between the velocity projections in the Earth’s and associated coordinate systems, the angles of attack and glide, and the wind speed. Then, the three wind speed projections are assigned unknown parameters, which are found using parameter identification. It is assumed that the wind has a constant speed and direction in the processed section of the flight. The accuracy characteristics of the proposed algorithm were evaluated based on the data obtained on the flight simulator of a modern training aircraft. In the course of simulation, random measurement errors were generated at the levels corresponding to the flight experiment. The influence of the type of maneuvers on the accuracy the three wind speed projections estimates was also studied. It is shown that for all considered maneuvers, that is "barrel", "snake", stepwise inputs, the errors in estimating the horizontal components of wind speed generally do not exceed 5 %, the vertical component 10 %, with the duration of the sliding processing interval of 0.5 and 1.0 s, which allows not only to estimate the constant wind speed, but also to track its change.

The Solution of the Inverse Problem of Identifying the Thermal Conductivity Tensor in Anisotropic Materials

On the basis of A. N. Tikhonov's regularization theory, a technique has been developed for solving inverse heat conduction problems of identifying the thermal conductivity tensor in a two-dimensional domain. Such problems are replaced by problems of identifying the principal heat conductivity coefficients and the orientation angle of the principal axes, with the principal coefficients being approximated by Schoenberg’s cubic splines. As a result, the problem is reduced to determining the unknown coefficients in these approximations and the orientation angle of the principal axes. With known boundary and initial conditions, the temperature in the domain will depend only on these coefficients and the orientation angle. If one expresses it by the Taylor formula for two terms of series and substitutes it into the Tikhonov functional, then the determination of the increments of the coefficients and the increment of the orientation angle can be reduced to solving a system of linear equations with respect to these increments. By choosing a certain regularization parameter as well as some functions for the principal thermal conductivity coefficients and the orientation angle as an initial approximation, one can implement an iterative process for determining these coefficients. After obtaining the vectors of the coefficients and the angle of orientation as a result of the converging iterative process, it is possible to determine the root-mean-square discrepancy between the temperature obtained and the temperature measured as a result of the experiment. It remains to choose the regularization parameter in such a way that this discrepancy is within the root-mean-square discrepancy of the measurement error. When checking the efficiency of using the proposed method, a number of two-dimensional test problems for bodies with known thermal conductivity tensors were solved. The influence of random measurement errors on the error in the identification of the thermal conductivity tensor was analyzed.