Low Coefficient Of Variation Values Research Articles

Verification of the analytical performance of the serum Folate assay on the Abbott Alinity ci®

In the evolving landscape of clinical diagnostics, the significance of folate takes center stage as precision and innovation shape advancements in analytical methodologies. Folate, a pivotal element in cellular metabolism, governs physiological processes and serves as an indicator for various medical conditions. This study employs the Chemiluminescent Microparticle Immunoassay (CMIA), known for its accuracy, to assess the reproducibility and repeatability of serum folate levels. Folate's role in cellular metabolism influences diverse physiological functions, making its precise quantification crucial for identifying and monitoring conditions such as folate deficiency. The CMIA method emerges as a robust approach, leveraging immunological specificity for high precision and reliability. Utilizing the Abbott Alinity ci® Analyzer, a technologically advanced clinical chemistry instrument, this study incorporates a systematic analytical method verification procedure. This involves quantification through a standardized protocol and a comparative analysis against criteria set by esteemed societies (RICOS and FSCB), ensuring comprehensive insights into analysis techniques. The reproducibility test, evaluating the impact of various factors on assay results, reveals low Coefficient of Variation (CV) values (CV1: 10.25%, CV2: 8.58%, CV3: 9.13%) across different levels. The results align with quality control limits, emphasizing the method's reliability. Repeatability assessment demonstrates exceptionally low CV values (CV1: 4.84%, CV2: 3.41%, CV3: 1.89%), highlighting the method's stability and precision under controlled conditions.

Monitoring multiyear individual tree flowering and yield reveals high variation among ‘Pinkerton’ avocado trees

ABSTRACT Most avocado cv. Pinkerton scions in Israel are grafted on seedling rootstocks, resulting in unstable yields. The objective of this study was to evaluate tree multiyear yield variation among ‘Pinkerton’ trees. We evaluated the flowering and yield variations among trees in two commercial avocado orchards, in Kibbutz Dan and Kibbutz Kfar-HaNassi, for 4 years. The multiyear average yield of the individual trees ranged from 9.5 to 73.7 kg tree−1 in Dan, and 1.7 to 53.8 kg tree−1 in Kfar-HaNassi, with coefficient of variation (CV) of 42% and 54%, respectively. Multiyear flowering intensity ranged from 2.7 to 4.9 and 2.41 to 5 (out of 5), with generally lower CV values of 14% and 26%, respectively. Multiyear alternate bearing index (ABI) ranged from 0.24 to 0.85 and 0.2 to 1, with CV of 25% and 32%, respectively. In Dan, the yield was negatively correlated with ABI. In Kfar-HaNassi, the yield was positively correlated with flowering intensity and negatively correlated with ABI. These results show that it may be important to monitor long-term individual tree yield, because removing low-yielding trees and selecting genetic material characterised by high yield and low ABI may be advantageous for establishing orchards with stable high yields.

Reproducible generation of human liver organoids (HLOs) on a pillar plate platform via microarray 3D bioprinting.

Human liver organoids (HLOs) hold significant potential for recapitulating the architecture and function of liver tissues in vivo. However, conventional culture methods of HLOs, forming Matrigel domes in 6-/24-well plates, have technical limitations such as high cost and low throughput in organoid-based assays for predictive assessment of compounds in clinical and pharmacological lab settings. To address these issues, we have developed a unique microarray 3D bioprinting protocol of progenitor cells in biomimetic hydrogels on a pillar plate with sidewalls and slits, coupled with a clear bottom, 384-deep well plate for scale-up production of HLOs. Microarray 3D bioprinting, a droplet-based printing technology, was used to generate a large number of small organoids on the pillar plate for predictive hepatotoxicity assays. Foregut cells, differentiated from human iPSCs, were mixed with Matrigel and then printed on the pillar plate rapidly and uniformly, resulting in coefficient of variation (CV) values in the range of 15-18%, without any detrimental effect on cell viability. Despite utilizing 10-50-fold smaller cell culture volume compared to their counterparts in Matrigel domes in 6-/24-well plates, HLOs differentiated on the pillar plate exhibited similar morphology and superior function, potentially due to rapid diffusion of nutrients and oxygen at the small scale. Day 25 HLOs were robust and functional on the pillar plate in terms of their viability, albumin secretion, CYP3A4 activity, and drug toxicity testing, all with low CV values. From three independent trials of in situ assessment, the IC50 values calculated for sorafenib and tamoxifen were 6.2 ± 1.6 μM and 25.4 ± 8.3 μM, respectively. Therefore, our unique 3D bioprinting and miniature organoid culture on the pillar plate could be used for scale-up, reproducible generation of HLOs with minimal manual intervention for high-throughput assessment of compound hepatotoxicity.

Near‐Nozzle Mixing for Additive Manufacturing of Cementitious Mortar: A Homogeneity Study

AbstractThis paper investigates the Near‐nozzle Mixing (NNM) technique for 3D printing cementitious mortar, focusing on achieving continuous and homogeneous material properties. The NNM's ability to print Natural Sand Mortar (NSM), Recycled Aggregate Mortar (RAM), and Lightweight Mortar (LWM) was assessed. Fresh and hardened properties of each mortar were examined, emphasizing standard deviation (STD) and coefficient of variation (CV) to measure material homogeneity. Fresh properties included slump flow, yield stress, air void volume, density, and water‐to‐cement ratio, while hardened properties covered compressive strength, flexural strength, hardened density, and thermal conductivity. Results showed low CV values for all mortar types, indicating high consistency and homogeneity. NNM showed is capability to print of various materials with customized properties. NSM showed the highest compressive strength, RAM balanced strength and sustainability, and LWM provided the best thermal insulation. The study highlights NNM's versatility and potential for construction applications requiring tailored properties, proving it a promising additive manufacturing solution. The research serves as a foundation for future studies on graded multi‐material printing.

Whole-liver flip-angle shimming at 7 T using parallel-transmit kT -point pulses and Fourier phase-encoded DREAM mapping.

To obtain homogeneous signal throughout the human liver at 7 T. Flip angle (FA) shimming in 7T whole-liver imaging was performed through parallel-transmit kT -pointpulses based on subject-specific multichannel absolute maps from Fourier phase-encoded dual refocusing echo acquisition mode (PE-DREAM). The optimal number of Fourier phase-encoding steps for PE-DREAM mapping was determined for a 7T eight-channel parallel-transmission system. FA shimming experiments were performed in the liver of 7 healthy subjects with varying body mass index. In these subjects, first shimming and Fourier PE-DREAM mapping were performed. Subsequently, three small-flip-angle 3D gradient-echo scans were acquired, comparing a circularly polarized (CP) mode, a phase shim, and a kT -point pulse. Resulting homogeneity was assessed and compared with estimated FA maps and distributions. Fourier PE-DREAM with 13 phase-encoding steps resulted in a good tradeoff between accuracy and scan time. Lower coefficient of variation values (average [min-max] across subjects) of the estimated FA in the volume of interest were observed using kT -points (7.4 [6.6%-8.0%]), compared with phase shimming (18.8 [12.9%-23.4%], p < 0.001) and CP (43.2 [39.4%-47.1%], p < 0.001). kT -points delivered whole-liver images with the nominal FA and the highest degree of homogeneity. CP and phase shimming resulted in either inaccurate or imprecise FA distributions. Here, locations having suboptimal FA in the estimated FA maps corresponded to liver areas suffering from inconsistent signal intensity and T1 -weighting in the gradient-echo scans. Homogeneous whole-liver 3D gradient-echo acquisitions at 7 T can be obtained with eight-channel kT -point pulses calculated based on subject-specific multichannel absolute Fourier PE-DREAM maps.

Three-dimensional CT imaging in extensor tendons using deep learning reconstruction: optimal reconstruction parameters and the influence of dose.

The purpose of this study was to assess the optimal reconstruction parameters and the influence of tube current in extensor tendons three-dimensional computed tomography (3D CT) using deep learning reconstruction, using iterative reconstruction as a reference. In the phantom study, a cylindrical phantom with a 3mm rod simulated an extensor tendon was used. The phantom images were acquired at tube current of 50, 100, 150, 200, and 250 mA. In the clinical study, CT scans of hand tendons were performed on nine hands from eight patients. All images were reconstructed using advanced intelligent clear-IQ engine (AiCE) parameters (body, body sharp, brain CTA, and brain LCD) and adaptive iterative dose reduction three dimensional (AIDR 3D). The objective image quality for tendon detectability was evaluated by calculating the low-contrast object specific contrast-to-noise ratio (CNRLO) in the phantom study and CNR and coefficient of variation (CV) in the clinical study. In the phantom study, CNRLO (at 200 mA) of AiCE parameters (body, body sharp, brain CTA, and brain LCD) and AIDR 3D were 5.2, 5.3, 5.3, 5.8, and 5.0, respectively. In the clinical study, AiCE brain CTA was higher CNR and lower CV values compared to other reconstruction parameters. AiCE without dose reduction may be an effective strategy for further improving the image quality of extensor tendons 3D CT. Our study suggests that the AiCE brain CTA is more suitable for extensor tendons 3D CT compared to other AiCE parameters.

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.

Comprehensive Evaluation of Rice Qualities under Different Nitrogen Levels in South China.

There is a need to comprehensively evaluate the rice quality of different rice varieties under different nitrogen treatments. Therefore, in this study, we used twenty-one hybrid indica rice varieties and twenty-three inbred japonica rice varieties with three nitrogen fertilizer levels to investigate differences in rice qualities. As compared with hybrid indica rice, inbred japonica rice had lower coefficient of variation values for grain shape, mild rice percentage, and head rice percentage, but relatively higher coefficient of variation values for chalkiness traits, appearance, and taste value of cooked rice. A principal component analysis and membership function method were used to comprehensively evaluate the qualities of rice. The overall eating quality value by sensory evaluation and head rice percentage explained 61.3% and 67.9% of the variations in comprehensive quality of hybrid indica rice and inbred japonica rice across different nitrogen levels, respectively. We also found that rice comprehensive quality was better under low nitrogen levels for hybrid indica rice, while for inbred japonica rice, properly increasing nitrogen application could improve the comprehensive quality.

Effects of a paddling-based high-intensity interval training prescribed using anaerobic speed reserve on sprint kayak performance.

The aim of this study was to investigate physiological and performance adaptations to high-intensity interval training (HIIT) prescribed as a proportion of anaerobic speed reserve (ASR) compared to HIIT prescribed using maximal aerobic speed (MAS). Twenty-four highly trained sprint kayak athletes were randomly allocated to one of three 4-weak conditions (N = 8) (ASR-HIIT) two sets of 6 × 60s intervals at ∆%20ASR (MAS-HIIT) six 2min paddling intervals at 100% maximal aerobic speed (MAS); or controls (CON) who performed six sessions/week of 1-h traditional endurance paddling at 70%-80% maximum HR. A graded exercise test was performed on a kayak ergometer to determine peak oxygen uptake (V̇O2peak), MAS, V̇O2/HR, and ventilatory threshold. Also, participants completed four consecutive upper-body wingate tests to asses peak and average power output. Significant increases in V̇O2peak (ASR-HIIT = 6.9%, MAS-HIIT = 4.8%), MAS (ASR-HIIT = 7.2%, MAS-HIIT = 4.8%), ASR (ASR-HIIT = -25.1%, MAS-HIIT = -15.9%), upper-body Wingate peak power output and average power output (p < 0.05 for both HIIT groups) were seen compared with pre-training. Also, ASR-HIIT resulted in a significant decrease in 500-m , and paddling time. Lower coefficient of variation values were observed for the percent changes of the aforementioned factors in response to ASR-HIIT compared to MAS-HIIT. Overall, a short period of ASR-HIIT improves 500-m and 1,000-m paddling performances in highly trained sprint kayak athletes. Importantly, inter-subject variability (CV) of physiological adaptations to ASR-HIIT was lower than MAS-HIIT. Individualized prescription of HIIT using ASR ensures similar physiological demands across individuals and potentially facilitates similar degrees of physiological adaptation.

The need for energy storage on renewable energy generator outputs to lessen the Geeth effect, i.e. short-term variations mainly associated with wind turbine active power output

Many studies investigating the short-term variations associated with the power output from wind turbine generators utilise simulated or modelled data in the analysis. This current study uses short-term empirical data downloaded directly from operational wind turbines via electrical power quality meters. The empirical data shows that the short-term variations (one-second or sub-one-second timeframe) occur continuously over most of the power output range. A novel name is proposed, the Geeth Effect, for this variability phenomenon. The Geeth Effect is measured using the coefficient of variation mathematical expression and is likely contributing to (i) lower-than-expected financial and environmental benefits associated with the vast increase in connected wind turbine capacity, (ii) significant challenges faced by the transmission system operator as they seek to deliver a stable electricity grid. Calculated coefficient of variation values include 64% (10-kW wind turbine), 46% (300-kW wind turbine), 30% (3-MW wind turbine), 1.4% (169-kW solar PV), and 3.2% (40-kW hydroelectric plant). Energy storage methods are recommended to minimise the Geeth Effect. Recommendations include the installation of (i) filters (supercapacitors) and (ii) battery energy storage systems, both systems connected to the output stage of the wind turbine generators. Supercapacitors are the preferred choice for wind turbines because of the continuous charge/discharge cycling events, which can be detrimental to battery energy systems. Low coefficient of variation values are desirable and high values undesirable.

Characterization of mechanical properties of soft tissues using sub-microscale tensile testing and 3D-Printed sample holder

Obtaining the mechanical properties of soft tissues is critical in many medical fields, such as regenerative medicine and surgical simulation training. Although various tissue-characterization methods have been developed, such as AFM, indentation, and elastography, there remain some limitations on their accuracy and validity for measuring small and fragile soft tissues. This paper presents a tensile testing technique to measure the mechanical properties of soft tissues directly and accurately. Tensile testing was chosen as the primary method because of its simple procedure and ability to derive mechanical properties without requiring many assumptions or complicated models. However, tensile testing on soft tissues presents challenges related to gripping the tissue sample without affecting its inherent properties, applying minuscule forces to the sample, and measuring the cross-section area and strain of the sample. To solve these issues, this study presents a sub-micro scale tensile testing system that uses a flexure mechanism and a novel 3D-printed sample holder for gripping the tissue samples. The system also measures tested samples' cross-section area and strain using two high-resolution cameras. The system was validated by testing standard materials and used to characterize the elastic modulus, yield stress, and yield strain of lung tissue slices from six different mice. The results from the validation tests showed a less than 2.5% error for elastic modulus values measured using the tensile tester. At the same time, results from the mice lung tissue measurements revealed qualitative findings that closely matched those seen in the literature and displayed low coefficient of variation values, demonstrating the high repeatability of the system.

On-Court Change of Direction Test: an Effective Approach To Assess COD Performance in Badminton Players.

The aim of this research was to assess the reliability of a specific change of direction test (i.e., “On-Court COD test”) in youth badminton players, evaluate the effect of age on On-Court COD performance, and examine its correlations with linear speed, change of direction speed, and vertical jump tests. Forty-two young badminton players (27 males and 15 females; age: 17.3±1.6 years, body height: 170.3±7.5 cm, body mass: 59.0±9.7 kg) were divided into two age groups (Under 17 years and under 19 years). Tests included: linear sprints (5, 10, and 20-m), bilateral/unilateral countermovement jumps, a hexagon test, traditional and modified 505 change of direction tests; and On-court COD. Results showed an excellent intraclass correlation coefficient score (0.90) and a very low coefficient of variation values (1.6%) for the On-Court COD test. Comparing age groups, under 19 players were significantly faster in linear sprints (i.e., 5, 15 and 20-m; small to moderate effect sizes) and in all change of direction tests (moderate to large effect sizes). Moreover, the On-Court COD test showed moderate to large (r=.513-.779) relationships with both acceleration and COD abilities in under 17 players, and with linear sprints, COD, and jump performances in under 19 players. These data indicate that the On-Court COD test is a useful and reliable means to assess COD performance in youth badminton players and it is associated with acceleration, sprint and jump performance.

Modulus of Elasticity of Elastic Tubes Used in Neuromuscular Rehabilitation Programs.

The elastic tubes have been used for clinical rehabilitation programs in which exercises are performed with submaximal intensities due to the difficulty in the measure the applied force. The authors aimed to quantify the elastic constant of elastic tubes used in neuromuscular rehabilitation programs predicting the force related to elastic tube elongation. A force test was performed by stretching the elastic tubes to determine the relationship between force and elongation. Eight elastic tubes with progressive levels of resistance represented by colors (yellow, red, blue, gray, black, grape, purple, and gold-low to higher resistance) were used. Experimental. The test and retest were compared using the paired t test. The agreement and reliability between the test versus retest of pooled means colors were analyzed by plotting the Bland-Altman graph and intraclass correlation coefficient and the coefficient of variation. Pearson correlation was used to verify the validity between measurements. The force values generated from the elastic tube elongation increase according to the color and thickness of elastic tubes with a strong and significant association between them (P < .0001). The elastic constant measurements were similar and presented high intraclass correlation coefficient values, low coefficient of variation values, and were reproducible (P < .0001). The force could be quantified according to elastic tube length variation by the linear regression equation with reproducibility. It gives greater measurement precision and better training load control when using elastic tubes in strength training programs.

Insufficient sampling frequencies skew heart rate variability estimates: Implications for extracting heart rate metrics from neuroimaging and physiological data

BackgroundWhile cardiac pulsations are widely present within physiological and neuroimaging data, it is unknown the extent this information can provide valid and reliable heart rate and heart rate variability (HRV) estimates. The objective of this study was to demonstrate how a slight temporal shift due to an insufficient sampling frequency can impact the validity/accuracy of deriving cardiac metrics. MethodsTwenty-two participants were instrumented with valid/reliable industry-standard or open-source electrocardiograms. Five-minute lead II recordings were collected at 1000 Hz in an upright orthostatic position. Following artifact removal, the 1000 Hz recording for each participant was downsampled to frequencies ranging 2–500 Hz. The validity of each participant’s downsampled recording was compared against their 1000 Hz recording (“reference-standard”) using Bland-Altman plots with 95 % limits of agreement (LOA), coefficient of variation (CoV), intraclass correlation coefficients, and adjusted r-squared values. ResultsDownsampled frequencies of ≥ 50 and ≥ 90 Hz produced highly robust measures with narrow log-transformed 95 % LOA (<±0.01) and low CoV values (≤3.5 %) for heart rate and HRV metrics, respectively. Below these thresholds, the log-transformed 95 % LOA became wider (LOA range: ±0.1–1.9) and more variable (CoV range: 1.5–111.6 %). ConclusionThese results provide an important consideration for obtaining cardiac information from physiological data. Compared to the “reference-standard” ECG, a seemingly negligible temporal shift of the systolic contraction (R wave) greater than 11-milliseconds (90 Hz) away from its true value, lessened the validity of the HRV. Further research is warranted to determine the minimum sampling frequency required to obtain valid heart rate/HRV metrics from pulsatile waveforms.

Homogeneity of the selected food mixes

The article presents the results of homogeneity assessments for selected food mixes based on computer image analysis. The study was conducted on müsli and condiment mixes standardly available on the consumer market. A total of 40 different ready-for-use products were analysed. Collected samples from three package of each product were placed in a special chamber and then photographed. Photographs were then subjected to computer image analysis to acquire information on the percentage content of individual components. Homogeneity assessment was based on the contents of a selected component called tracer and the coefficient of variation (CV). Lower CV values (3.02–27.31%) and thus better homogeneity was observed for condiment mixes as compared to müsli mixes (3.57–59.15%). Fourteen of twenty condiment mixes had adequate (acceptable at CV ≤ 10%) mixing degree. For the müsli, only six of the tested mixes had appropriate homogeneity. The presented results are a preliminary to developing an image-based methodology for determining the uniformity of granular dry food mixes.

Comparison between Dense L-Band and C-Band Synthetic Aperture Radar (SAR) Time Series for Crop Area Mapping over a NISAR Calibration-Validation Site

Crop area mapping is important for tracking agricultural production and supporting food security. Spaceborne approaches using synthetic aperture radar (SAR) now allow for mapping crop area at moderate spatial and temporal resolutions. Multi-frequency SAR data is highly useful for crop monitoring because backscatter response from vegetation canopies is wavelength dependent. This study evaluates the utility of C-band Sentinel-1B (Sentinel-1) and L-band ALOS-2 (PALSAR) data, collected during the 2019 growing season, for generating accurate active crop extent (crop vs. non-crop) classifications over an agricultural region in western Canada. Evaluations were performed against the Agriculture and Agri-Food Canada satellite-based Annual Cropland Inventory (ACI), an open data product that maps land cover across the extent of Canada’s agricultural land. Classifications were performed using the temporal coefficient of variation (CV) approach, where an optimal crop/non-crop delineating CV threshold (CVthr) is selected according to Youden’s J-statistic. Results show that crop area mapping agreed better with the ACI when using Sentinel-1 data (83.5%) compared to PALSAR (73.2%). Analysis of performance by crop reveals that PALSAR’s poorer performance can be attributed to soybean, urban, grassland, and pasture ACI classes. This study also compared CV values to in situ wet biomass data for canola and soybeans, showing that crops with lower biomass (soybean) had correspondingly lower CV values.

A low coefficient of variation in hepatic triglyceride concentration in an inbred rat strain

BackgroundInbred strains are characterized by less genetic variation, which suggests usefulness of inbred strains for evaluations of various parameters. In this study, experimental reproducibility in several parameters was compared between an outbred Wistar rat and Wistar King A Hokkaido (WKAH/HkmSlc) rat, the inbred strain that is originated from Wistar rats.MethodsDifference of variations was investigated in parameters of body compositions and liver functions such as body weight, liver weight, liver triglycerides (TG), liver cholesterol and plasma alanine aminotransferase activity (ALT) between WKAH rats and outbred Wistar rats by using the coefficient of variation (CV).ResultsThere was no difference in the CVs of body weight and relative liver weight between WKAH and Wistar rats. The CVs of body weight and relative liver weight were below 10% in both WKAH and Wistar rats. The CVs of TG, cholesterol, and ALT in Wistar rats were between 30 and 40%, whereas those in WKAH rats were between 10 and 25%. A low CV level of TG was observed in WKAH rats compared to that in Wistar rats regardless of the duration of the experimental period in those rat strains.ConclusionThe low CV values in metabolic parameters involved in liver functions in the inbred rats suggested an advantage of using inbred rather than outbred rats for the evaluation of liver lipid metabolism.

Reliability and characterisation of the 20-maximum trampoline jump test

BACKGROUND: The 20-maximum trampoline jump test is a commonly used performance measure in competitive trampoline gymnastics. However, its reliability and characteristics are poorly understood. OBJECTIVE: To determine the reliability of the 20-maximum trampoline jump test and describe its characteristics. METHODS: Thirty-two national and international level trampoline gymnasts (18 ± 5 years) performed two, 20-maximal straight jump tests, separated by 24–72 hours. Time of flight (total, jumps 1–10 and jumps 11–20), force (average and peak), horizontal displacement and contact time were measured by a competition standard system. Test-retest reliability was assessed using intraclass correlation coefficient (ICC), typical error, and coefficient of variation (CV). RESULTS: Total time of flight significantly decreased between trial 1 (31.80 ± 1.98 s) and trial 2 (31.43 ± 1.99 s; p&lt; 0.05), however test-retest reliability was excellent (ICC = 0.96, CV = 1.3%). Other time of flight and force measures significantly decreased from trial 1 to trial 2, whereas contact time increased. All secondary measures displayed very high ICC (0.95–0.99) and low CV values (0.5–1.9%), except horizontal displacement (ICC = 0.54, CV = 20.6%). CONCLUSION: The 20-maximum test possesses excellent reliability for the assessment of trampoline performance in a wide population of national and international level gymnasts.

Evaluation of PEG-based hydrogel influence on estrogen receptor driven responses in MCF7 breast cancer cells.

Extracellular matrix (ECM) mimicking hydrogel scaffolds have greatly improved the physiological relevance of in vitro assays, but introduce another dimension that creates variability in cell related readouts when compared to traditional 2D cells-on-plastic assays. We have developed a synthetic poly(ethylene glycol) (PEG) based ECM mimicking hydrogel and tested it against two gold standard animal-based naturally derived hydrogel scaffolds in MCF7 cell response. We have used the percent coefficient of variation (CV) as a metric to evaluate the reproducibility of said responses. Results indicated that PEG hydrogels performed similarly to naturally derived gold standards, and variance was similar in basic characterization assays, such as viability and cell adherence. PEG based hydrogels had lower CV values in estrogen receptor driven responses to several doses of estrogen in both estrogen receptor transactivation and estrogen induced proliferation.

Use of the anaerobic speed reserve to normalize the prescription of high-intensity interval exercise intensity

The aim of this study was to compare the perceptual and physiological responses and time-to-exhaustion in high intensity interval exercise (HIIE) protocols that are prescribed based on the relative anaerobic speed reserve (ASR) or maximal aerobic speed (MAS) in athletes with different ASR values, as well as the coefficient of variation (CV) of the abovementioned variables. Eleven long-distance runners and ten rugby players were submitted to five experimental sessions on different days; the first and second session were intended for the determination of the anthropometry, MAS and maximal sprint (MSS). In the subsequent sessions, three HIIE15:15s protocols were performed until exhaustion (110%MAS, Δ25%ASR, and Δ50%ASR) in random order. The anthropometric characteristics and variables obtained from the MAS and MSS tests in the different groups were compared by Student’s unpaired t-test. The analysis of mixed models for repeated measures (groups and protocols) was used to compare the speed, delta blood lactate, rating of perceived exertion, and time-to-exhaustion. Rugby players presented higher ASR (13.6 ± 0.9 km h−1) compared to long-distance runners (12.6 ± 0.9 km h−1) (P = .049). For the HIIE15:15s protocols, there were no protocol and group interaction effects. However, lower CV values were observed for time-to-exhaustion (a mean reduction of 52%) and delta blood lactate (a mean reduction of 48%) in Δ25%ASR and Δ50%ASR when compared to 110%MAS. Furthermore, the rating of perceived exertion CV was similar in all HIIE15:15s protocols. The prescription of intensity of HIIE based on the ASR was able to reduce the inter-subject variability of lactate and time-to-exhaustion in rugby players and long-distance runners.