Standard Deviation Of Differences Research Articles

Heart rate variability: Obtaining the stress score from SDNN values

BACKGROUND: Heart Rate Variability (HRV) is a non-invasive method of assessing the autonomic nervous system response during exercise and fatigue. OBJECTIVE: The aim of the study was to analyze the validity and feasibility of the stress score index (SS) calculated from SDNN values during exercise. METHODS: 18 Men performed 2 running tests: 1) incremental exercise test; 2) 10-minute constant load test. Subjects underwent HRV analysis during the constant load test, before both tests, and afterward in a seated position at 3 intervals (0’–5’, 5’–10’, 10’–15’). The relationship between SDNN and SD2 was analyzed before, during, and after the test. SS was calculated as 1/SD2*1000. The Bland-Altman test analyzed the reliability of ESS. The bias, limits of agreement (LoA), standard deviation of difference, intraclass correlation (ICC), and person coefficient were calculated. RESULTS: The bias was 0.15 ± 2.54 (UperLOA: 2.54; LowerLOA: -2.23). In all conditions, SD2 and SDNN showed a positive linear relationship (r2 = 0.986); SS and ESS were correlated; and SS and ESS described a positive linear relationship (r2 = 0.993). CONCLUSIONS: The SS index calculation from SDNN is a reliable alternative during exercise.

Mathematical modeling of thin-layer drying kinetics and moisture diffusivity study of apple slices using infrared conveyor-belt dryer.

The drying features of apples at different infrared drying settings were investigated. The drying time, moisture-effective diffusion, and activation energy of infrared dried apples were measured experimentally and statistically as a function of slice thicknesses, radiation intensity, and air velocity. The infrared intensity of 0.225, 0.130, and 0.341W/cm2 , slice thicknesses of 6, 4, and 2mm, and airflow of 0.5, 1.0, and 1.5m/s were used to dry apple slices. The data shows that the drying time reduced as IR increased, but airflow and slice thickness increased. Eight statistical factors were used to compare 11 alternative mathematical drying models. The experimentally acquired drying curves were matched to the thin-layer drying equations. According to the calculations, the Midilli etal. equation had the greatest (efficiency and R2 ) and lowest (χ2 , sum of squared errors, standard error of estimate, standard error, standard deviation of difference) values. As a result, this equation is the best for modeling the drying curves of apple slices across all drying circumstances. The optimum moisture diffusivity value varied from 2.59 to 9.07 × 10-10 m2 /s. The mean activation energy was determined to be 19.02-29.83kJ/mol under various experimental conditions.

Heart Rate Variability Measured from Wearable Devices as a Marker of Disease Severity in Tetanus.

Tetanus is a disease associated with significant morbidity and mortality. Heart rate variability (HRV) is an objective clinical marker with potential value in tetanus. This study aimed to investigate the use of wearable devices to collect HRV data and the relationship between HRV and tetanus severity. Data were collected from 110 patients admitted to the intensive care unit in a tertiary hospital in Vietnam. HRV indices were calculated from 5-minute segments of 24-hour electrocardiogram recordings collected using wearable devices. HRV was found to be inversely related to disease severity. The standard deviation of NN intervals and interquartile range of RR intervals (IRRR) were significantly associated with the presence of muscle spasms; low frequency (LF) and high frequency (HF) indices were significantly associated with severe respiratory compromise; and the standard deviation of differences between adjacent NN intervals, root mean square of successive differences between normal heartbeats, LF to HF ratio, total frequency power, and IRRR, were significantly associated with autonomic nervous system dysfunction. The findings support the potential value of HRV as a marker for tetanus severity, identifying specific indices associated with clinical severity thresholds. Data were recorded using wearable devices, demonstrating this approach in resource-limited settings where most tetanus occurs.

A simple and low-cost paper-based device for simultaneous determination of hematocrit and hemoglobin levels in point-of-care settings

Hematocrit and hemoglobin levels are common blood tests used to assess the overall health status of patients as well as the oxygen-carrying capacity of the blood. The gold-standard technologies to determine the hematocrit and hemoglobin levels are precise and fast, but they are not pragmatic in extreme point-of-care settings due to the prohibitive cost, process complexity, and sophisticated facilities. Therefore, here, we report the development of a microfluidic paper-based analytical device to determine hematocrit and hemoglobin levels simultaneously. This device exploits the area of the stain formed by a spreading drop of 20 μl of whole blood on Whatman filter paper immobilized with sodium chloride and ethylenediaminetetraacetic acid for hematocrit level, whereas for hemoglobin concentration, it utilizes the gray color intensity of a 20 μl droplet of a mixture of blood and de-ionized water. The performance of the device is verified by comparing with gold-standard results of the automated hematology analyzer, showing a high degree of correlation (R2) of 0.9651 and 0.9701 for hematocrit and hemoglobin levels, respectively. The bias and standard deviation of the differences between the two measurements for hematocrit determination are 0.002 and 1.005, respectively, while the bias and standard deviation of differences between the two methods for hemoglobin determination are 0.065 and 0.398, respectively. This device is likely to provide a simple, fast, disposable, and inexpensive tool to determine the hematocrit and hemoglobin levels in resource-constraint settings.

Physiological and psychological stress response of blood donors during the blood donation process.

Blood donation can be a potentially stressful event, leading to the activation of an acute stress response. Knowing and identifying potential stressors could help in optimizing the donation experience. The present study aimed to measure the physiological and psychological stress changes before, during and after blood donation. Physiological and psychological stress response was assessed in 70 blood donors. To evaluate physiological stress response, pulse rate, respiratory rate, blood pressure (BP), beat-to-beat BP and lead II electrocardiogram were recorded. Baroreflex sensitivity was calculated using the available software. Psychological stress response was assessed using the State-Trait Anxiety Inventory scale. A significant increase in systolic blood pressure, diastolic blood pressure and mean arterial pressure was observed in the pre-donation period (p < 0.001). Among the time-domain parameters, SDSD (standard deviation of differences between adjacent respiratory rate intervals) and RMSSD (root mean square of the successive differences) were significantly lower during the post-donation period (p < 0.005, p < 0.007, respectively). Among the frequency-domain parameters, LF nu (relative power of the low-frequency band in normalized units), HF nu (relative power of the high-frequency band in normalized units) and LF% (relative power of the low-frequency band in percentage) were significantly lower before donation compared to during donation (p < 0.001, p < 0.001 and p < 0.012, respectively). LF nu, LF% and LF/HF ratio were also significantly lower during donation compared to after donation (p < 0.05, p < 0.016 and p < 0.042, respectively). Baroreflex sensitivity was also statistically higher during the pre-donation period. State score was significantly higher among the blood donors during the pre-donation period. Physiological and psychological stress is experienced by blood donors during the pre-donation period. A pre-donation informative conversation should be carried out with each blood donor and potential stressors should be identified in each.

Image encoding selection based on Pearson correlation coefficient for time series anomaly detection

Recently, anomaly detection in time-series data has received great attention from researchers due to its importance in problem-solving and predicting future system events. The majority of researchers combine convolutional neural networks (CNN) with image-encoding methods, including Gramian Angular Field (GAF) and Markov Transition Field (MTF). The selection of the right image-encoding method typically involves an iterative evaluation process that requires extensive computational time. This study proposes descriptive statistical analysis and Pearson correlation to find the correlation between statistical features in the encoded data from each image encoding and CNN accuracy. This information is essential for determining the image encoding method without image conversion processes and CNN trials, thus accelerating the computational time. The method tested on the initial dataset showed that the standard-deviation difference has the highest correlation with CNN accuracy (with a Pearson correlation coefficient of r = 0.944), followed by the mean difference (r = 0.705) and the count difference (r = 0.455), also resulting in a 95.35 % reduction in the computation time. The validity of this result was confirmed through the evaluation of several new datasets with different anomaly patterns, making this proposed approach suitable for selecting an appropriate image-encoding method.

Group trends and individual variability in writing development: a descriptive grammatical complexity analysis

Abstract This study aims to examine group trends and individual variability of descriptive Grammatical Complexity (GC) in writing development. A longitudinal sample of 41 high school EFL learners is followed for an academic year (12 waves of data collection), resulting in a corpus of 492 texts, coded for eight descriptive GC features of academic writing. Our analysis reveals different sets of descriptive GC features relevant to capturing group trends and individual variability in writing development. At the group level, two phrasal-level GC features could capture significant changes in group means over time; at the individual level, four types of clausal and phrasal GC features showed significant associations between individual variability over time (measured by Standard Deviation of differences) and gains (as measured by the increase of usage frequency). Findings are discussed with regard to modeling both inter-individual and intra-individual trajectories in writing development and pedagogical implications attuned to both group and individual needs.

“O Youth and Beauty:” Children's looks and children's cognitive development

We use data from the 11 waves of the U.S. Study of Early Child Care and Youth Development 1991–2005, following children from ages 6 months through 15 years. Observers rated videos of them, obtaining measures of looks at each age. Given their family income, parents’ education, race/ethnicity, and gender, being better-looking raised subsequent changes objective learning outcomes. The gains imply a long-run impact on cognitive achievement of about 0.04 standard deviations per standard deviation of differences in looks. Similarly specified models describing changes in reading and arithmetic scores at ages 7, 11 and 16 in the U.K. National Child Development Survey 1958 cohort show larger effects, 0.20 standard deviations. The extra gains persist when instrumenting children's looks by their mother's looks, and do not work through measures of teachers’ reports of closeness to children, mothers’ reports of children's behavior, their victimization by bullies, or self-confidence. Results from the U.K. data show that greater childhood beauty raises educational attainment both directly and indirectly, through impacts on test scores, thus contributing to higher adult earnings.

Six Years of IKFS-2 Global Ozone Total Column Measurements

Atmospheric ozone plays an important role in the biosphere’s absorbing of dangerous solar UV radiation and its contributions to the Earth’s climate. Nowadays, ozone variations are widely monitored by different local and remote sensing methods. Satellite methods can provide data on the global distribution of ozone and its anomalies. In contrast to measurement techniques based on solar radiation measurements, Fourier-transform infrared (FTIR) satellite measurements of thermal radiation provide information, regardless of solar illumination. The global distribution of total ozone columns (TOCs) measured by the IKFS-2 spectrometer aboard the “Meteor M N2” satellite for the period of 2015 to 2020 is presented. The retrieval algorithm uses the artificial neural network (ANN) based on measurements of TOCs by the Aura OMI instrument and the method of principal components for representing IKFS-2 spectral measurements. Latitudinal and seasonal dependencies on the ANN training errors are analyzed and considered as a first approximation of the TOC measurement errors. The TOCs derived by the IKFS-2 instrument are compared to independent ground-based and satellite data. The average differences between the IKFS-2 data and the independent TOC measurements are up to 2% (IKFS-2 usually slightly underestimates the other data), and the standard deviations of differences (SDDs) vary from 2 to 4%. At the same time, both the analysis of the ANN approximation errors of the OMI data and the comparison of the IKFS-2 results with independent data demonstrate an increase in discrepancies towards the poles. In the spring–winter period, SDDs reach 8% in the Southern and 6% in the Northern Hemisphere. The technique presented can be used to process the IKFS-2 spectral data, and as a result, it can provide global information on the TOCs in the period of 2015–2020, regardless of the solar illumination and the presence of clouds.

Effects of foam rolling and strength training on post exercise hypotension in normotensive women: A cross-over study

Foam rolling (FR) has recently become very popular among athletes and recreational exercisers and is often used during warm up prior to strength training (ST) to induce self-myofascial release. The purpose was to examine the acute effects of ST and FR performed in isolation or in combination on blood pressure (BP) responses during recovery in normotensive women. Sixteen normotensive and strength trained women completed four interventions: 1) rest control (CON), 2) ST only, 3) FR only, and 4) ST immediately followed by FR (ST + FR). ST consisted of three sets of bench press, back squat, front pull-down, and leg press exercises at 80% of 10RM. FR was applied unilaterally in two sets of 120 s to each of the quadriceps, hamstring, and calf regions. Systolic (SBP) and diastolic (DBP) BP were measured before (rest) and every 10 min, for 60 min, following (Post 10–60) each intervention. Cohen's d effect sizes were calculated to indicate the magnitude effect by the formula d = Md/Sd, where Md is the mean difference and Sd is the standard deviation of differences. Cohen's d effect-sizes were defined as small (≥0.2), medium (≥0.5), and large (≥0.8). There were significant reductions in SBP for ST at Post-50 (p < 0.001; d = −2.14) and Post-60 (p < 0.001; d = −4.43), for FR at Post-60 (p = 0.020; d = −2.14), and for ST + FR at Post-50 (p = 0.001; d = −2.03) and Post-60 (p < 0.001; d = −2.38). No change in DBP was observed. The current findings suggest that ST and FR performed in isolation can acutely reduce SBP but without an additive effect. Thus, ST and FR can both be used to acutely reduce SBP and, importantly, FR can be added to a ST regimen without furthering the SBP reduction during recovery.

A study of the role of seven historically significant fast-response hygrometers and sensor calibration on eddy covariance H2O fluxes and surface energy balance closure

Water vapor fluxes are a major component of the surface energy balance, hydrological cycle, and ecosystem processes. As newer sensors are developed for eddy covariance measurements, the role of different technologies and calibration uncertainties on H2O fluxes and surface energy balance closure should be assessed. Here, a field intercomparison is described testing historically significant fast-response hygrometers: Lyman-α, KH2O, LI-7000, LI-7500, LI-7200, EC155, and EC150. This study occurred in southeastern Wyoming in September 2015. Three methods of calibration are investigated: standard calibration with a dew point generator and zero-air gas, referencing to a first principles slow-response hygrometer, and piecewise calibration between fast-response hygrometers based on blocks of time with consistent relationships between 5-minute data. Differences in fluxes among the infrared gas analyzers were largest when using the standard calibration (maximum difference of 15.9%, standard deviations of differences between 4.1–6.0%) with differences reduced by 0.3–0.6 × when the calibrations were referenced to a first principles hygrometer. The smallest differences occurred using the piecewise calibration, which emphasizes the intrinsic differences among the sensor technologies, where differences were further reduced by 0.04–0.09 × (maximum difference of 8.2%, standard deviations of differences between 2.3–3.0%). The Lyman-α and KH2O experienced severe drifts, though their piecewise calibrations were generally within the range of the others. The two most influential factors beyond calibration uncertainty were the oxygen correction for the ultraviolet absorption sensors, especially the KH2O, and the tube attenuation spectral correction for closed-path analyzers, mostly with the lower flow EC155. The effect of hygrometers on the energy balance closure was minor with some uncertainty associated with the standard calibration, though this was less than the change in closure associated with the choice of sonic anemometer. These results focus attention on the need to further develop accurate calibration methodologies that are suitable for all flux tower sites.

Effect of Ramipril on Cardiac Autonomic Neuropathy in Patients With Type II Diabetes Mellitus.

Background Cardiovascular autonomic neuropathy (CAN), an important form of DAN is caused by the impairment of the autonomic nerve fibers that innervate the heart and blood vessels and leads to abnormalities in cardiovascular dynamics. The earliest finding of CAN, even at the subclinical stage, is a decrease in heart rate variability (HRV). Objective The objective is to assess the effect of ramipril 2.5mg once daily on cardiac autonomic neuropathyin type II DM patients as an add-on to a standard antidiabetic regimen for a duration of 12 months. Materials and methods A prospective, open-label,randomized, parallel-group study was conducted on type II DM with autonomic dysfunction. Patients in Group A received tablet ramipril 2.5mg daily along with the standard antidiabetic regimen which consist of Tab Metformin 500mg twice a day and Tab Vildagliptin 50mg twice a day and group B received only the standard antidiabetic regimen for 12 months. Results Among 26 patients with CAN, 18 patients completed the study. After one year in group A, Delta HR value increases from 9.77±1.71 to 21.44±8.44 and the E:I ratio (ratio of the longest R-R interval during expiration and shortest R-R intervalduring inspiration) improved from 1.23±0.35 to 1.29±0.23 signifying significant improvement in parasympathetic tone. Results of the postural test showed significant improvement in SBP.Analysis of HRV by time domain method showed that the standard deviation of RR (SDRR) interval and Standard deviation of differences between adjacent RR interval (SDSD)value increased significantly in group A.Analysis of HRV frequency domain indices showed that LFP:HFP ratio improved after treatment in ramipril group indicating improvement in sympatho-vagal balance. Conclusion Ramipril improves parasympathetic component more as compared to sympathetic component of DCAN in type II DM. Ramipril could be a promising option having favorable long-term outcomes in diabetic patients especially when treatment begins at subclinical stage.

Validation of a monoclonal unconjugated estriol antibody for use in prenatal maternal serum screening.

Unconjugated estriol (uE3) is used as a marker for fetal aneuploidy in maternal serum screening tests. The goal of this study was to examine the validity of a new immunoassay for uE3 that uses a monoclonal antibody (m-uE3) rather than the more commonly used polyclonal antibody (p-uE3). Assays were performed in the Special Chemistry laboratory at Women and Infants Hospital of Rhode Island. Residual fresh (n = 100) and frozen (n = 533) second trimester serum samples from routine clinical care were tested using p-uE3 and/or m-uE3 assays. Assay results were compared between methods using Bland-Altman plots. A median equation was developed for m-uE3 results. Down syndrome risks were compared between the two assays in a case-control sample set (21 cases each matched with five controls for the completed week of gestation, duration of freezer storage and race). Log-transformed serum uE3 levels were highly correlated between the assays (r = 0.93, p < 0.001), with the m-uE3 assay levels yielding, on average, 23% higher (standard deviation of differences in log uE3 concentrations = 0.07) results. Assay and gestation-based median equations were calculated and used to convert m-uE3 concentrations to multiples of the median (MoM). The m-uE3 MoM values fit a log Gaussian distribution well with a log standard deviation of 0.11. Down syndrome risk results were not significantly different between assays. The m-uE3 assay, with results expressed in MoMs, is suitable for screening and as a monoclonal-based assay offers the advantage of a predictable and indefinite supply of antibody to perform the assay.

Quantification of swallowing movements by ultrasound imaging in normal and disordered subjects

Ultrasound imaging may be useful for tracking oral-pharyngeal structures of the vocal tract critical for effective swallowing, but use of this technology has been hampered by a lack of validation against standard clinical measures derived from x-ray video fluoroscopy (Modified Barium Swallow Studies or MBSS). Here, we compare quantitative tracking of hyoid bone and tongue motion from ultrasound imaging and simultaneously measured MBSS from a range of participants with disordered and healthy swallowing behavior. The proximal edge of the hyoid bone in MBSS and ultrasound recordings is tracked using CASM (Computational Analysis of Swallowing Mechanics) software, while tongue motion is tracked using TonguePART software, originally developed for analysis of speech. Hyoid trajectories and velocities measured from synchronized ultrasound and MBSS recordings are compared and standard deviations of differences between the two measurements are evaluated. Tongue motion during swallowing is characterized by analysis of root, dorsum, and blade displacement, velocity, and timingas well as tongue base retraction in the pharynx. Preliminary findings show quantitatively similar patterns in ultrasound and MBSS, suggesting that ultrasound has potential utility as an accessible tool for bedside diagnosis and biofeedback. Characteristic patterns separating normal from healthy swallowing, as well as potential therapeutic targets for biofeedback treatment of dysphagia, will be discussed.

Abstract P238: Gait Characteristics in Older Adults Using the Protokinetics Zeno Walkway: The Atherosclerosis Risk in Communities Study

Introduction: Slowed gait speed in older adults is associated higher vascular disease burden, greater risk of dementia, and falls. Gait mat measurement technology captures speed as well as additional gait parameters, with potential importance for better risk prediction and identification in older adults, but normative data are needed. We assessed correlations between mat-measured gait speed and gait parameters to identify potential targets for future gait research. We hypothesized that gait parameters would not correlate with overall mat-measured gait speed as strongly as overall gait speed correlates within repeat trials of mat or stopwatch-measured trials. Methods: Participants (n = 402, mean age: 81 years, 54% women, 19% Black race) from the Atherosclerosis Risk in Communities Study completed two consecutive usual pace walks on Zeno Walkway™ gait mats at visit 8. Two-hundred thirty-six participants additionally completed two 4-meter usual pace walks timed by stopwatch. We assessed validity using the difference between the faster of two trials each for mat- and stopwatch-measured gait speed using Bland-Altman plots, and Pearson’s correlations, and examined reliability with consecutive trials within measurement type. We reported mean, standard deviation, range, and correlation of 37 gait parameters with gait speed, as well as intra-person variability (coefficient of variation) and parameter asymmetry between footfalls. Results: Participants had an average gait speed of 0.92 m/sec (SD 0.19 m/sec) measured by mat and 0.99 m/sec (SD 0.21 m/sec) by stopwatch. Mat-measured gait speed was strongly correlated with stopwatch measured speed (Pearson’s Correlation 0.85). Mat-measured walks were on average 0.08 m/sec faster than paired stopwatch-measured walks (standard deviation of difference 0.11 m/sec, p&lt;0.001), regardless of gait speed. Consecutive mat walks had higher Pearson’s and R-squared correlations (0.95 and 0.90) than consecutive stopwatch walks (0.89 and 0.83). Of 37 gait parameters tested, 9 were positively correlated (Pearson’s correlations 0.64 to 0.76) and 7 were negatively correlated (Pearson’s correlations -0.64 to -0.42) with gait speed. Parameter variability in single stance center of pressure distance and gait speed was moderately negatively correlated (Pearson’s correlation -0.50). Correlations between gait speed and gait parameter asymmetry were low (&lt;|0.33|). Conclusions: Gait mat technology shows high reliability and high correlation with stop-watch measurement in older adults in the ARIC population. Additional gait parameters were largely not strongly correlated with gait speed, including step-to-step measures of variability and asymmetry, suggesting avenues for future research to evaluate gait differences more granularly as more sensitive indicators of health risk in older adults.

Impact of telemedicine on glycemic control in type 2 diabetes mellitus during the COVID-19 lockdown period.

The lockdown at the start of coronavirus disease 2019 (COVID-19) pandemic in Saudi Arabia (March 2020 to June 2020) shifted routine in-person care for patients with type 2 diabetes mellitus (T2DM) to telemedicine. The aim of this study was to investigate the impact telemedicine had during this period on glycemic control (HbA1c) in patients with T2DM. 4,266 patients with T2DM were screened from five Ministry of National Guard Health Affairs hospitals in the Kingdom of Saudi Arabia. Age, gender, body mass index (BMI), HbA1c (before and after the COVID-19 lockdown), duration of T2DM, comorbidities and antidiabetic medications data were obtained. Mean and standard deviation of differences in HbA1c were calculated to assess the impact of telemedicine intervention. Correlations between clinically significant variances (when change in the level is ≥0.5%) in HbA1c with demographics and clinical characteristic data were determined using chi square test. Most of the participants were Saudis (97.7%) with 59.7% female and 56.4% ≥60 years of age. Obesity was 63.8%, dyslipidemia 91%, and hypertension 70%. Mean HbA1c of all patients slightly rose from 8.52% ± 1.5% before lockdown to 8.68% ± 1.6% after lockdown. There were n=1,064 patients (24.9%) whose HbA1c decreased by ≥0.5%, n =1,574 patients whose HbA1c increased by ≥0.5% (36.9%), and n =1,628 patients whose HbA1c changed by <0.5% in either direction (38.2%). More males had significant improvements in glycemia compared to females (28.1% vs 22.8%, p<0.0001), as were individuals below the age of 60 years (28.1% vs 22.5%, p<0.0001). Hypertensive individuals were less likely than non-hypertensive to have glycemic improvement (23.7% vs 27.9%, p=0.015). More patients on sulfonylureas had improvements in HbA1c (42.3% vs 37.9%, p=0.032), whereas patients on insulin had higher HbA1c (62.7% vs 56.2%, p=0.001). HbA1c changes were independent of BMI, duration of disease, hyperlipidemia, heart and kidney diseases. Telemedicine was helpful in delivering care to T2DM patients during COVID-19 lockdown, with 63.1% of patients maintaining HbA1c and improving glycemia. More males than females showed improvements. However, the HbA1c levels in this cohort of patients pre- and post-lockdown were unsatisfactorily high, and may be due to in part lifestyle, age, education, and hypertension.

A detailed quasigeoid model of the Hong Kong territories computed by applying a finite-element method of solving the oblique derivative boundary-value problem

Abstract New gravity and precise levelling measurements have been performed throughout the Hong Kong territories to modernize a vertical geodetic datum that is currently realized by heights of levelling benchmarks defined in the Hong Kong Principal Datum (HKPD). Modernization of the HKPD involved delivering various products, including new detailed geoid and quasigeoid models and newly determined orthometric and normal heights of levelling benchmarks. In this study, we present the result of gravimetric quasigeoid modelling. The method used to compute a detailed gravimetric quasigeoid model is based on the finite-element method to solve the geodetic boundary-value problem with oblique derivative boundary conditions considered directly at computational nodes on the discretized Earth’s topography. The result of a gravimetric quasigeoid modelling shows a good agreement with a geometric quasigeoid model at the Global Navigation Satellite System (GNSS)-levelling benchmarks. The standard deviation of differences between the gravimetric and geometric quasigeoid heights of ±3.3 cm is compatible with the expected accuracy of gravity, levelling, and GNSS measurements.

The associations between physical-test performance and match performance in women's Rugby Sevens players.

Evaluating the relationships between physical-test and match performance in team sports could be useful for training prescription and athlete evaluation. Here we investigated these relationships in women's Rugby Sevens. Thirty provincial-representative players performed Bronco-fitness, countermovement-jump, acceleration, speed, and strength tests within two weeks before a two-day tournament. Match-running and match-action performance measures were provided by GPS units and video analysis. Generalised and general linear mixed models were employed to estimate the effect of a two standard-deviation difference in physical-test measures on match measures. Effect magnitudes were assessed via standardisation (using the between-player SD) and, for effects on tries scored, also via match winning (based on simulating matches). Evidence for substantial and trivial true magnitudes was provided by one-sided interval-hypothesis tests and Bayesian analysis. There was good evidence of positive effects of many physical-test measures on match high-intensity running, with large effects for jump height and acceleration. There was some evidence of small-moderate positive effects of speed and Bronco, and of small-moderate negative effects of maximal strength and jump height, on match total running and high intensity changes in speed. The evidence was generally inadequate for associations between physical-test measures and match actions, but there was good evidence of small-large positive effects of back squat and jump height on tries scored. Enhancing players' jump height and back-squat performance might therefore increase the likelihood of match success in women's Rugby Sevens.

Racial effects on Masimo pulse oximetry: a laboratory study

Recent publications have suggested that pulse oximeters exhibit reduced accuracy in dark-skinned patients during periods of hypoxemia. Masimo SET® (Signal Extraction Technology®) has been designed, calibrated, and validated using nearly equal numbers of dark and light skinned subjects, with the goal of eliminating differences between pulse oximetry saturation (SpO2) and arterial oxygen saturation (SaO2) values due to skin pigmentation. The accuracy concerns reported in dark-skinned patients led us to perform a retrospective analysis of healthy Black and White volunteers. Seventy-five subjects who self-identified as being racially Black or White underwent a desaturation protocol where SaO2 values were decreased from 100 to 70%, while simultaneous SpO2 values were recorded using Masimo RD SET® sensors. Statistical bias (mean difference) and precision (standard deviation of difference) were − 0.20 ± 1.40% for Black and − 0.05 ± 1.35% for White subjects. Plots of SpO2 versus SaO2 show no significant visible differences between races throughout the saturation range from 70 to 100%. Box plots grouped in 1% saturation bins, from 89–96%, and plotted against concomitant SaO2 values, show that occult hypoxemia (SaO2 < 88% when SpO2 = 92–96%) occurred in only 0.2% of White subject data pairs, but not in any Black subjects. There were no clinically significant differences in bias (mean difference of SpO2-SaO2) found between healthy Black and White subjects. Occult hypoxemia was rare and did not occur in Black subjects. Masimo RD SET® can be used with equal assurance in people with dark or light skin. These laboratory results were obtained in well-controlled experimental conditions in healthy volunteers—not reflecting actual clinical conditions/patients.

Feasibility of deconvolution-based multiphase CT angiography perfusion maps in acute ischemic stroke: Simulation and concordance with CT perfusion

ObjectivesIntegration of CT perfusion (CTP) with requisite non-contrast CT and CT angiography (CTA) stroke imaging may allow efficient stroke lesion volume measurement. Using surrogate images from CTP, we simulated the feasibility of using multiphase CTA (mCTA) to generate perfusion maps and assess target mismatch profiles. Materials and methodsPatients with acute ischemic stroke who received admission CTP were included in this study. Four CTP images (surrogate mCTA, one pre-contrast and three post-contrast, starting at the arterial peak then at 8 s intervals) were selected according to the CTP arterial time-density curve to simulate non-contrast CT and mCTA images. Cerebral blood flow (CBF) and Tmax maps were calculated using the same model-based deconvolution algorithm for the standard CTP and surrogate mCTA studies. Infarct and penumbra were delineated with CBF < 20% and Tmax > 6 s threshold, respectively. Classification accuracy of surrogate mCTA target mismatch (infarct <70 ml; penumbra ≥15 ml; mismatch ratio ≥1.8) with respect to standard CTP was assessed. Agreement between infarct and penumbra volumes from standard CTP and surrogate mCTA maps were evaluated by Bland-Altman analysis. ResultsOf 34 included patients, 28 had target mismatch and 6 did not by standard CTP. Accuracy of classifying target mismatch profiles with surrogate mCTA was 79% with respect to that from standard CTP. Mean ± standard deviation of differences (standard CTP minus surrogate mCTA) of infarct and penumbra volumes were 9.8 ± 14.8 ml and 20.1 ± 45.4 ml, respectively. ConclusionsSurrogate mCTA ischemic lesion volumes agreed with those from standard CTP and may be an efficient alternative when CTP is not practical.