Coefficient Of Variation Values Research Articles

1450-P: Profiles of Glycemic Control in People with Type 1 Diabetes Using CGM—A Clustering Approach in the SFDT1 Study

CGM-derived data are usually analyzed in silos, metric by metric, for diabetes care or therapeutic strategy. Simultaneous analysis of the various dimensions of glycemic control would allow a more comprehensive overview. We analyzed data of people with type 1 diabetes (PWT1D) in the SFDT1 cohort study. A K-means clustering model was developed with HbA1c, coefficient of variation (CV), time in range (TIR), time below 70 mg/dl (TBR), Gold score and Glycemic Risk Index (GRI). We included 618 participants (53% men, age 41±14 years) from 20 centres in France. The optimal model had 3 clusters. The “Euglycemia” cluster (n=280, 45%) was characterized by a high TIR (mean 69.3%); low TBR ​​(4.2%), TAR (time above 180 mg/dl: 26.5%), CV (35.7%), HbA1c (7.0%) and GRI (36.4) values. The “Hyperglycaemia" cluster (n=197, 32%) was characterized by high TAR (56.5%), GRI (71.8) and HbA1c (8.5%) and low TIR (40.3%), TBR (3.2%) and Gold score (2.3). The “Hypoglycemia” cluster (n=141, 23%) was characterized by high TBR (15.8%), CV (46.1%), GRI (69.2) and Gold score (3.0). Participants in the “Hyperglycemia” cluster were younger, socially vulnerable, and had more frequent hypertension than those in the “Euglycemia” cluster. To conclude, we identified three distinct, clinically relevant glycemic control profiles, enabling better characterization of PWT1D and, thus, more personalised management. Disclosure E.Cosson: Board Member; Abbott, Medtronic. G.A.Aguayo: None. L.Sablone: None. M.Huet: None. J.Riveline: Board Member; Abbott Diabetes, Medtronic, Dexcom, Inc., Novo Nordisk, Eli Lilly and Company, Sanofi. G.Fagherazzi: Advisory Panel; Roche Diabetes Care, Consultant; AbbVie Inc., Lilly. Sfdt1 study team: n/a.

Improving microstructural integrity, interstitial fluid, and blood microcirculation images from multi-b-value diffusion MRI using physics-informed neural networks in cerebrovascular disease.

To obtain better microstructural integrity, interstitial fluid, and microvascular images from multi-b-value diffusion MRI data by using a physics-informed neural network (PINN) fitting approach. Test-retest whole-brain inversion recovery diffusion-weighted images with multiple b-values (IVIM: intravoxel incoherent motion) were acquired on separate days for 16 patients with cerebrovascular disease on a 3.0T MRI system. The performance of the PINN three-component IVIM (3C-IVIM) model fitting approach was compared with conventional fitting approaches (i.e., non-negative least squares and two-step least squares) in terms of (1) parameter map quality, (2) test-retest repeatability, and (3) voxel-wise accuracy. Using the in vivo data, the parameter map quality was assessed by the parameter contrast-to-noise ratio (PCNR) between normal-appearing white matter and white matter hyperintensities, and test-retest repeatability was expressed by the coefficient of variation (CV) and intraclass correlation coefficient (ICC). The voxel-wise accuracy of the 3C-IVIM parameters was determined by 10,000 computer simulations mimicking our in vivo data. Differences in PCNR and CV values obtained with the PINN approach versus conventional fitting approaches were assessed using paired Wilcoxon signed-rank tests. The PINN-derived 3C-IVIM parameter maps were of higher quality and more repeatable than those of conventional fitting approaches, while also achieving higher voxel-wise accuracy. Physics-informed neural networks enable robust voxel-wise estimation of three diffusion components from the diffusion-weighted signal. The repeatable and high-quality biological parameter maps generated with PINNs allow for visual evaluation of pathophysiological processes in cerebrovascular disease.

Agro-ecological Assessment of the Preponderance of Rill Erosion Channels under Different Land Cover Types in Humid Tropics of Akamkpa, Southeastern Nigeria

Agro-ecological assessment of proliferation of rill erosion channels in the humid tropic was conducted between January and July 2022. The purpose of the study was to seek possibility of preventing proliferation of rill erosion channels using a variety of crops; vetiver grass, potato plant, groundnut and fallow vegetation in erosion control. Different land slopes of 4, 5 and 6 per cents representing blocks 1,2 and 3 were used for the study. Soil samples were collected from each unit for laboratory determination of soil textural characteristics. Plots dimension of 10m x 80m were delineated on each slope to form a block. Sub plots of 10m x 10m were delineated from each block for each crops cover types. In-situ measurement of parameters, viz; number of rill erosion channels, length, width and depth of channels were accomplished. The total number of rill channels from each crops’ plot was statistically analyzed to determine their Coefficient of Variation (CV). The CV values for vetiver, potatoes, groundnut, fallow vegetation and control plot indicated; 40.50%, 31.11%, 60.62%, 38.00% and 62.50% respectively. Result of channel characteristics showed that fallow plot recorded the lowest number of channels of 1.8, width of 2.3cm and length of 142.5cm respectively. Average length and depth recorded in vetiver plots are 143cm and 1.6cm, Potatoes has a total depth of 2.2cm and length of 194.3cm. Similar result was recorded in fallow plot, indicating that vetiver, potatoes and fallow vegetation exhibited similar erosion control potential. Conversely, the highest length, width and depth and number of rill channels were traced to control plot with a mean of 3.8 spillways, depth of 4.8cm, width of 25.8cm and mean length of 312.5cm seconded by groundnut plot. Implying, soil protection as well as crop production can be guaranteed with the right choice of crops in the humid tropics

Repeatability of a fully automated swept-source optical coherence tomography biometer and agreement with a low coherence reflectometry biometer

BackgroundTo evaluate the repeatability of a fully automated swept-source optical coherence tomography (SS-OCT) and its agreement with an optical low coherence reflectometry (OLCR) for several biometric parameters.MethodsIn this study, 74 eyes of 74 patients were measured using the Eyestar 900 SS-OCT and Lenstar LS 900 OLCR. Flat keratometry (K1) and steep keratometry (K2), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were measured three times with each device. The repeatability was analyzed with the intrasubject standard deviation, coefficient of variability (CoV), and coefficient of repeatability (CoR) for each instrument. The agreement between the instruments was evaluated with Bland-Altman analysis.ResultsK1, K2 and CCT CoV values were < 0.2%, < 0.4% and < 0.55%, respectively. Higher CoV values were found for ACD and LT ranging from 0.56% to 1.74%. The lowest CoV values were found for the AL measurements (0.03% and 0.06% for the Eyestar 900 and the Lenstar LS 900, respectively). AL measurements provided the highest repeatability, measured with both CoV and CoR values, and the CCT was the parameter with the lowest repeatability. The CCT and LT measurements were statistically significant between the two biometers (P < 0.001). The interval of the limits of agreement was < 0.6 D for K1 and K2, 15.78 µm for CCT, 0.21 mm for ACD, 0.34 mm for LT, and 0.08 mm for AL.ConclusionsBoth biometers provide repeatable measurements for the different parameters analyzed and can be used interchangeably.

РАЗРАБОТКА ОТЕЧЕСТВЕННОЙ ИММУНОФЕРМЕНТНОЙ ТЕСТ-СИСТЕМЫ ДЛЯ ДЕТЕКЦИИ ANTI-HEV IGМ В СЫВОРОТКЕ КРОВИ

Background. Though the Republic of Belarus does not belong to countries endemic for viral hepatitis E, numerous studies have proved that hepatitis E virus (HEV) actively circulates among humans and animals. However, the circulation is latent that makes it difficult to diagnose the infection in a timely manner. Objective. To develop and evaluate the quality of a domestic ELISA test system for the detection of anti-HEI IgM. Material and methods. 96-well plates, recombinant proteins ORF2 and ORF3 of the 3rd HEV genotype, conjugate of monoclonal antibodies to human IgM with horseradish peroxidase, solutions for dilution of serums and conjugate containing bovine serum albumin. Results. The recommended concentrations of recombinant polypeptides ORF2 and ORF3 of hepatitis E virus genotype 3 for sorption are 2 and 1 μg/ml, respectively. The optimum dilution of the conjugate is 1:13 000. False positive and false negative results were not detected, sensitivity and specificity being at least 99%. The mean value for coefficient of variation within one plate is 6.4%, within two plates is 11.3%. Conclusions. The characteristics of the developed national test system comply with the recommended standards, thus indicating the possibility of its implementation into clinical laboratory diagnostics.

Homogeneity of Two Semisolid Formulations Using Simple In-tube Mixing Method

To accelerate therapeutic effects, the mixtures of two or more topical pharmaceutical products having different medicinal purposes are often applied in the medical field. In this study, we aimed to develop a simple mixing method/procedure to achieve excellent homogeneity in the mixture of two topical products, a steroidal ointment and a skin moisturizer. To assess an in-tube mixing method as a simple mixing procedure, we injected both topical products into an empty resin tube, a flexible hollow tube with an open end that can be closed on one side, and a closed end on the other, removed as less air as possible inside the tube, and then thermocompressed (sealed) the open end to close it. The two topical products were then mixed uniformly by repeated finger pressure along the longitudinal axis of the tube. The homogeneity of the two topical products in the tube was evaluated by measuring the content of methyl paraoxybenzoate (MP), an additive loaded in the skin moisturizer. In addition, the mixability was qualitatively evaluated from the distribution of white petrolatum, another additive loaded in the steroid ointment, using Raman spectroscopy. As a result, the measured value of MP relative to the label claim was in the range of 100±12%, and the coefficients of variation value was also less than 12%. These results indicate that the in-tube mixing method using two topical products is approximately hologenetic preparations that do not cause therapeutic problems.

SEASONAL EFFECT ON BLOOD PRESSURE VARIABILITY IN HYPERTENSIVE PATIENTS ASSESSED BY DIFFERENT MEASUREMENT METHODS

Objective: The seasonal variation in temperature is well known to affect the level of blood pressure (BP). However, its impact on BP variability is uncertain. This study investigated the seasonal variation in BP variability in hypertensive patients assessed using office and out-of-office BP measurements. Design and method: Adult hypertensives on stable antihypertensive drug treatment were assessed with office (OBP), home (HBP), and ambulatory BP (ABP) measurements in winter, next summer, and in the next winter. BP variability was quantified using the standard deviation (SD) and coefficient of variation (CV). Results: Fifty-eight participants had complete data for winter and summer (mean age 65.2±7.9 [SD], 64% males, 21% obese, 48% smokers, 11% diabetes, 18% cardiovascular disease, 28% on a single antihypertensive drug, 38% on 2 drugs, 34% on &gt; 2 drugs). OBP, HBP and daytime ABP were lower in summer than in winter (P&lt;0.01), whereas nighttime ABP was unchanged (P = NS) (Figure). SD and CV for systolic OBP were higher in winter than summer (P&lt;0.01/&lt;0.05, respectively). BP variability assessed by HBP and ABP measurement did not differ in winter and summer (Figure). Forty participants had complete data for winter-summer-next winter. OBP, HBP and daytime ABP were higher in the second winter compared with summer excluding any order effect. Respective CV values showed no difference (p = NS). Conclusions: These preliminary data suggest that despite the considerable impact of seasonal changes in temperature on the levels of BP, its variability is not affected. Thus, variability appears to be an intrinsic feature of the individual's BP behaviour, which is largely unaffected by extrinsic seasonal factors.

Automated and rapid chemiluminescence immunoassay for cardiac troponin I based on digital microfluidics

Rapid diagnosis of acute myocardial infarction (AMI) is critical in the clinical setting. An automated and rapid chemiluminescence immunoassay system based on digital microfluidics (DMF) is suggested for cardiac troponin I (cTnI). This method involves a double antibody sandwich structure. The cTnI antigen in the sample to be analyzed was captured by magnetic beads encapsulated with the cTnI antibody, which was subsequently recognized by the biotin-labeled secondary antibody. Horseradish peroxidase (HRP)-labeled streptavidin may be conjugated to biotin and used to mark the cTnI antigen because of the unique way that biotin binds to avidin. The simultaneous recognition of the cTnI antigen by primary and secondary antibodies in sandwich form, as well as the high specificity of the reaction between streptavidin and biotin, considerably improves the sensitivity and specificity of this technique for cTnI detection. This approach has decent stability. For cTnI samples, the full process took 40 min, with a limit of detection (LOD) of 0.34 ng mL−1. Additionally, there was a significant correlation range from 0.39 to 25 ng mL−1, with a correlation value of 0.994. The CV (Coefficient of variation) value was 2.26%. This system is anticipated to be used for the clinical measurement of cTnI in human serum.

Hierarchically hollow microcapsules with antibacterial and angiogenic properties for abdominal wall defects treatment

The utilization of mesh materials to repair abdominal wall defects (AWDs) is one of the most common operations in the surgical field. However, the repair efficiency for biological meshes is restricted by poor neovascularization and limited abilities to prevent bacterial contamination. To address these issues, we design a new type of hierarchically hollow microcapsules (HHMs) by microfluidics. The hollow mesoporous silica nanoparticles filled in the aqueous core of HHMs form the first hollow structure, while the polymer shell of HHMs with tailorable thickness forms the second hollow structure. Under the precise emulsification process of microfluidics, HHMs have a high monodispersity with the coefficient of variation value about 1.9%. Taking advantages of the hierarchically hollow structure, the resultant microcapsules can store large amounts of angiogenic molecules, and deliver these cargos in a controlled manner. In vitro experiments find that the bioactivities of angiogenic molecules are well preserved after microencapsulation and promote the capillary tube formation of endothelial cells. In addition, silver nanoparticles (AgNPs) are incorporated into the HHMs shell to provide antibacterial properties for these microcapsules. When AgNPs concentration set to 0.4‰, the colony counting is reduced by 99.8% for Gram-negative bacteria and 94.8% for Gram-positive bacteria, while the proliferation activity of normal cells remains more than 80.0%. In vivo experiments find that HHMs can facilitate the new blood vessel formation, restrain the bacteria adhesion, and decrease the inflammatory response after implantation into a rat model with AWDs. These unique characteristics of HHMs thus create a healthy environment for biological meshes to induce the regeneration of AWDs, accompanied by collagen deposition and granulation formation. Collectively, the proposed HHMs are promising devices in the application of defected tissue repair.

Wind Vulnerability of Flexible Outdoor Single-Post Billboards

Increased temperature due to global climate change is increasing the magnitude and frequency of extreme winds making billboard structures more vulnerable. This paper proposes a methodology to determine the structural safety of flexible outdoor single-post billboards. A CFD model of a flexible single-post billboard was performed as an example. Resultant wind forces were obtained for the previous model using different wind speeds. A mechanical numerical model of the billboard was realized, and this was subjected to the resultant wind forces. Internal forces for the most vulnerable places of the billboard were obtained for all different adopted wind speeds. Next, a reliability analysis of the billboard was performed considering several values for the bias factor and coefficient of variation for the internal forces caused by wind. Safety levels determined from the reliability analysis indicate that a billboard designed with a nominal wind speed of 180 km/h cannot achieve the target probability index of 3.2 for wind speed higher or equal to 200 km/h for any of the adopted probabilistic parameters. Significant differences in the found safety levels for the evaluated probability parameters indicate that billboard structures could undergo safety values below the target one with changes in the case where wind characteristics endanger this type of structure.

Optimization of operating parameters for spraying microbial (Bacillus thuringiensis and Beauveria bassiana) based bio-pesticide solutions for foliar application

Exposure to mechanical stresses developed due to different components of spraying system may cause permanent damage to the microbes of bio-pesticide solutions. To achieve maximum effectiveness of spray application, proper selection of nozzle size and operating pressure is critical. Two different classes of bio-pesticides viz. bacterial-based Bacillus thuringiensis (BBP solution) and fungal-based Beauveria bassiana (FBP solution) were evaluated for spray application by three hollow cone nozzles (1.14, 2.35 and 3.56 mm in diameter) at four operating pressures (145, 245, 345 and 445 kPa). It was observed that viability of bio-pesticide solutions increases with decrease in operating pressure and increase in nozzle size. The nozzle orifice diameter and operating pressure of the spraying system were optimized to get desired application rate, volume median diameter (VMD) and coefficient of variation (CV) of spray for maximum microbial viability of bio-pesticide solutions. The optimized values of application rate (323.94-and 325.58 L ha−1), VMD (225.88 and 231.89 µm), CV (84.49 and 85.99%) and viability (6.63 × 106 and 6.06 × 106 cfu ml−1) were obtained for BBP and FBP solutions, respectively at nozzle orifice size of 3.56 mm and 145 kPa operating pressure.

The influence of age on the match-to-match variability of physical performance in women's elite football.

Introduction: The fluctuation of external match load throughout a season is influenced by several contextual factors. While some, have been deeply analysed in men's football literature, information is lacking on how other contextual elements, such as player's age or experience, may affect the match-to-match variability of locomotor activities. In fact, aging has been described as a multifactorial process with the potential to affect human performance. The aim of this study is to assess if the variability of match locomotor performances fluctuates according to the players' age. Methods: 59 female players from four top-level clubs were divided into three age groups and monitored during two seasons using GPS APEX (STATSports, Northern Ireland), with a sampling frequency of 10Hz, in 150 official matches to determine the coefficient of variation (CV) of full-match and 1-min peak locomotor demands of total distance (TD), high-speed running distance, sprint distance (SpD), accelerations, and decelerations. To test whether there was a group effect of age on match-to-match variability we used a one-way ANOVA with CV% as the independent variable. Results: CV values of full match variables ranged from 3.8% to 27.8%, with total distance (3.8%) in the peak age group and SpD (27.8%) in the pre-peak age group. Similarly, CV values of 1-min peaks ranged from 4.1% (post-peak group) in TD to 22.3% (peak group) in SpD. Discussion: The main finding was that there were no significant differences between the different age groups in the metrics analysed although trends indicate less variability in the post-peak age group.

An assessment of microvascular hemodynamics in human macula

An adequate blood supply to meet the energy demands is essential for any tissue, particularly for high energy demand tissues such as the retina. A critical question is: How is the dynamic match between neuronal demands and blood supply achieved? We present a quantitative assessment of temporal and spatial variations in perfusion in the macular capillary network in 10 healthy human subjects using a non-invasive and label-free imaging technique. The assessment is based on the calculation of the coefficient of variation (CoV) of the perfusion signal from arterioles, venules and capillaries from a sequence of optical coherence tomography angiography images centred on the fovea. Significant heterogeneity of the spatial and temporal variation was found within arterioles, venules and capillary networks. The CoV values of the capillaries and smallest vessels were significantly higher than that in the larger vessels. Our results demonstrate the presence of significant heterogeneity of spatial and temporal variation within each element of the macular microvasculature, particularly in the capillaries and finer vessels. Our findings suggest that the dynamic match between neuronal demands and blood supply is achieved by frequent alteration of local blood flow evidenced by capillary perfusion variations both spatially and temporally in the macular region.

Analysis of corneal topographic and endothelial cell properties in newly diagnosed obstructive sleep apnea patients: A case-control study

PurposeTo investigate the topographic features and endothelial cell changes in the corneas of patients with newly diagnosed obstructive sleep apnea (OSA). BackgroundThis cross-sectional case-control study included 98 patients with OSA and 90 healthy controls. OSA was diagnosed on the basis of a polysomnographic sleep examination. Patients with OSA were grouped according to their apnea-hypopnea index (AHI) scores. Corneal topographic measurements were obtained using the Scheimpflug–Placido disk topographer, and keratometry values, anterior chamber parameters, thinnest corneal thickness, symmetry index (SI), keratoconus vertex (KV), and the Baiocchi-Calossi-Versaci index, including keratoconus (KC) screening indexes, were recorded. The corneal endothelium was visualizedby specular microscopy, and the endothelial cell density, coefficient of variability (CV), and percentage of hexagonal cells (HEX) were recorded. ResultsIn this study, 32 patients had mild, 34 patients had moderate, and 32 patients had severe OSA. The mean back KV (KVb) and back SI values were significantly higher in the OSA group than in the control group (P <0.001, P = 0.035, respectively). As body mass index (BMI) increased, KVb also increased significantly (r = 0.281; P = 0.009). The mean CV and HEX values differed significantly between the OSA and control groups (P = 0.012 and P = 0.002, respectively). In addition, a significant correlation was found between AHI and KVb and CV values (r = 0.315; P <0.001 and r = 0.231; P = 0.011, respectively). ConclusionsThis study revealed abnormal changes in the corneal endothelial morphology and topographic KC screening indexes in relation to OSA severity in patients and controls. Further research is required to determine the effect of BMI on corneal topographic findings in patients with OSA.

A strategy to treat coagulopathy in patients with massive hemorrhage

To investigate the topographic features and endothelial cell changes in the corneas of patients with newly diagnosed obstructive sleep apnea (OSA).This cross-sectional case-control study included 98 patients with OSA and 90 healthy controls. OSA was diagnosed on the basis of a polysomnographic sleep examination. Patients with OSA were grouped according to their apnea-hypopnea index (AHI) scores. Corneal topographic measurements were obtained using the Scheimpflug–Placido disk topographer, and keratometry values, anterior chamber parameters, thinnest corneal thickness, symmetry index (SI), keratoconus vertex (KV), and the Baiocchi-Calossi-Versaci index, including keratoconus (KC) screening indexes, were recorded. The corneal endothelium was visualizedby specular microscopy, and the endothelial cell density, coefficient of variability (CV), and percentage of hexagonal cells (HEX) were recorded.In this study, 32 patients had mild, 34 patients had moderate, and 32 patients had severe OSA. The mean back KV (KVb) and back SI values were significantly higher in the OSA group than in the control group (P <0.001, P = 0.035, respectively). As body mass index (BMI) increased, KVb also increased significantly (r = 0.281; P = 0.009). The mean CV and HEX values differed significantly between the OSA and control groups (P = 0.012 and P = 0.002, respectively). In addition, a significant correlation was found between AHI and KVb and CV values (r = 0.315; P <0.001 and r = 0.231; P = 0.011, respectively).This study revealed abnormal changes in the corneal endothelial morphology and topographic KC screening indexes in relation to OSA severity in patients and controls. Further research is required to determine the effect of BMI on corneal topographic findings in patients with OSA.

Within-person variability of urinary neonicotinoids and their metabolites and recommendation for sampling strategy

Humans are exposed to neonicotinoid insecticides (NEOs) from various routes. Urine has been widely used to characterize the internal exposure levels of NEOs in humans. However, variable sampling methods can result in highly variable measurements of NEOs, potentially leading to misunderstanding of human exposure. In this study, we collected the first morning voids urine (FMVU), spot urine (SU), and 24 h urine (24hU) samples from 8 healthy adults during 7 consecutive days. The concentration, variability, and reproducibility of six parent NEOs (p-NEOs) and three NEOs metabolites (m-NEOs) were measured. Over 79 % of the urine samples had detectable levels of NEOs. Dinotefuran (DIN) and olefin-imidacloprid (of-IMI) were excreted in the highest concentration of p-NEO and m-NEO, respectively. All of the p-NEOs except thiacloprid (THD) and of-IMI were recommended as biomarkers for biomonitoring studies. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were used to evaluate the temporal variability and reproducibility of urinary NEOs in SU, FMVU and 24hU, respectively. We observed low ICCs ranging from 0.016 to 0.39 for NEOs regardless of the sample types. However, the higher CV and lower ICC values observed in SU samples suggested lower reproducibility compared to FMVU and 24hU samples. Significant correlations of several NEOs between FMVU and 24hU were also observed in the current study. Considering the comparable concentrations and similarity between FMVU and 24hU, our study proposed possible biomarkers and indicated that the potential for FMVU samples to estimate adequately an individual's exposure to NEOs. Therefore, we suggested FMVU as a sampling strategy in future human biomonitoring studies, while multiple samples were recommended to detect exposure over time intervals of weeks or months.

A New Hybrid Exponentially Weighted Moving Average Control Chart with Repetitive Sampling for Monitoring the Coefficient of Variation

The implementation of Statistical Quality Control (SQC) has been tracked in various areas, such as agriculture, environment, industry, and health services. The employment of SQC methodologies is frequently employed for monitoring and identification of process irregularities across various fields. This research proposes and implements a novel SQC methodology in agricultural areas. A control chart is one of the SQC tools that facilitates real-time monitoring of multiple activities, including agricultural yield, industrial yield, and hospital outcomes. Advanced control charts with symmetrical data are being subjected to the new SQC method, which is suitable for this purpose. This research aims to develop a novel hybrid exponentially weighted moving average control chart for detecting the coefficient of variation (CV) using a repetitive sampling method called the HEWMARS-CV control chart. It is an effective tool for monitoring the mean and variance of a process simultaneously. The HEWMARS-CV control chart used the repetitive sampling scheme to generate two pairs of control limits to enhance the performance of the control chart. The proposed control chart is compared with the classical HEWMA and Shewhart control charts regarding the average run length (ARL) when the data has a normal distribution. The Monte Carlo simulation method is utilized to approximate the ARL values of the proposed control charts to determine their performance. The proposed control chart detects small shifts in CV values more effectively than the existing control chart. An illustrative application related to monitor the wheat yield at Rothamsted Experimental Station in Great Britain is also incorporated to demonstrate the efficiency of the proposed control chart. The efficiency of the proposed HEWMARS-CV control chart on the real data shows that the proposed control chart can detect a shift in the CV of the process, and it is superior to the existing control chart in terms of the average run length.

An Investigation on the Possible Application Areas of Low-Cost PM Sensors for Air Quality Monitoring.

In recent years, the availability on the market of low-cost sensors (LCSs) and low-cost monitors (LCMs) for air quality monitoring has attracted the interest of scientists, communities, and professionals. Although the scientific community has raised concerns about their data quality, they are still considered a possible alternative to regulatory monitoring stations due to their cheapness, compactness, and lack of maintenance costs. Several studies have performed independent evaluations to investigate their performance, but a comparison of the results is difficult due to the different test conditions and metrics adopted. The U.S. Environmental Protection Agency (EPA) tried to provide a tool for assessing the possible uses of LCSs or LCMs by publishing guidelines to assign suitable application areas for each of them on the basis of the mean normalized bias (MNB) and coefficient of variance (CV) indicators. Until today, very few studies have analyzed LCS performance by referring to the EPA guidelines. This research aimed to understand the performance and the possible application areas of two PM sensor models (PMS5003 and SPS30) on the basis of the EPA guidelines. We computed the R2, RMSE, MAE, MNB, CV, and other performance indicators and found that the coefficient of determination (R2) ranged from 0.55 to 0.61, while the root mean squared error (RMSE) ranged from 11.02 µg/m3 to 12.09 µg/m3. Moreover, the application of a correction factor to include the humidity effect produced an improvement in the performance of the PMS5003 sensor models. We also found that, based on the MNB and CV values, the EPA guidelines assigned the SPS30 sensors to the "informal information about the presence of the pollutant" application area (Tier I), while PMS5003 sensors were assigned to the "supplemental monitoring of regulatory networks" area (Tier III). Although the usefulness of the EPA guidelines is acknowledged, it appears that improvements are necessary to increase their effectiveness.

Quality Control of Targeted Plasma Lipids in a Large-Scale Cohort Study Using Liquid Chromatography-Tandem Mass Spectrometry.

High-throughput metabolomics has enabled the development of large-scale cohort studies. Long-term studies require multiple batch-based measurements, which require sophisticated quality control (QC) to eliminate unexpected bias to obtain biologically meaningful quantified metabolomic profiles. Liquid chromatography-mass spectrometry was used to analyze 10,833 samples in 279 batch measurements. The quantified profile included 147 lipids including acylcarnitine, fatty acids, glucosylceramide, lactosylceramide, lysophosphatidic acid, and progesterone. Each batch included 40 samples, and 5 QC samples were measured for 10 samples of each. The quantified data from the QC samples were used to normalize the quantified profiles of the sample data. The intra- and inter-batch median coefficients of variation (CV) among the 147 lipids were 44.3% and 20.8%, respectively. After normalization, the CV values decreased by 42.0% and 14.7%, respectively. The effect of this normalization on the subsequent analyses was also evaluated. The demonstrated analyses will contribute to obtaining unbiased, quantified data for large-scale metabolomics.

Probability of unsatisfactory performance of monopile foundations for offshore wind turbines considering variations in seabed properties

Safe design of monopiles for Offshore Wind Turbines (OWT) requires an accurate estimation of the foundation soil material properties. Uncertainty in soils is mainly due to their inherent variability which involves various spatial and temporal processes they have been exposed to over their natural geological process. The limited amount of information from geotechnical investigations in the seabed, considering the size of OWT farms, adds to the uncertainty. Commonly used deterministic design approaches idealize soil layers by assigning average values to the mechanical soil properties and make use of empirical correlations that can significantly differ from offshore conditions. Probabilistic design approaches have been suggested in the literature to account for the effect of uncertainties on the foundation’s performance by applying a coefficient of variation (COV) to soil properties. Such methods include theoretical investigations by applying selected COV values to predetermined mean CPT profiles for sands and undrained shear strength for clays. This study calculates the probability of unsatisfactory performance, Pfsys, of monopiles in sands by implementing variation in friction angle and unit weight using current API and DNV-GL design guidelines. Monte Carlo Simulation is employed to generate random fields using lognormal, normal, and uniform distributions. Pfsys is presented for a case study found in the literature and a design exercise for which local COV for the Belgian coast is also proposed.