Power Of Test Research Articles

Exercise microdosing for skeletal muscle health applications to spaceflight.

Findings from a recent 70-day bedrest investigation suggested intermittent exercise testing in the control group may have served as a partial countermeasure for skeletal muscle size, function, and fiber-type shifts. The purpose of the current study was to investigate the metabolic and skeletal muscle molecular responses to the testing protocols. Eight males (29 ± 2 yr) completed muscle power (6 × 4 s; peak muscle power: 1,369 ± 86 W) and V̇o2max (13 ± 1 min; 3.2 ± 0.2 L/min) tests on specially designed supine cycle ergometers during two separate trials. Blood catecholamines and lactate were measured pre-, immediately post-, and 4-h postexercise. Muscle homogenate and muscle fiber-type-specific [myosin heavy chain (MHC) I and MHC IIa] mRNA levels of exercise markers (myostatin, IκBα, myogenin, MuRF-1, ABRA, RRAD, Fn14, PDK4) and MHC I, IIa, and IIx were measured from vastus lateralis muscle biopsies obtained pre- and 4-h postexercise. The muscle power test altered (P ≤ 0.05) norepinephrine (+124%), epinephrine (+145%), lactate (+300%), and muscle homogenate mRNA (IκBα, myogenin, MuRF-1, RRAD, Fn14). The V̇o2max test altered (P ≤ 0.05) norepinephrine (+1,394%), epinephrine (+1,412%), lactate (+736%), and muscle homogenate mRNA (myostatin, IκBα, myogenin, MuRF-1, ABRA, RRAD, Fn14, PDK4). In general, both tests influenced MHC IIa muscle fibers more than MHC I with respect to the number of genes that responded and the magnitude of response. Both tests also influenced MHC mRNA expression in a muscle fiber-type-specific manner. These findings provide unique insights into the adaptive response of skeletal muscle to small doses of exercise and could help shape exercise dosing for astronauts and Earth-based individuals.NEW & NOTEWORTHY Declines in skeletal muscle health are a concern for astronauts on long-duration spaceflights. The current findings add to the growing body of exercise countermeasures data, suggesting that small doses of specific exercise can be beneficial for certain aspects of skeletal muscle health. This information can be used in conjunction with other components of existing exercise programs for astronauts and might translate to other areas focused on skeletal muscle health (e.g., sports medicine, rehabilitation, aging).

The Relationship Between Various Jump Tests and Baseball Pitching Performance: A Brief Review

ABSTRACT Multidirectional ground reaction forces (GRFs) and jump tests within baseball pitchers provide insight into athletic ability and coordination to produce lower-body force and power. Lower-body power is a biomechanical feature that denotes physiological capacity through dynamic and passive tissue stretch-shortening in transferring energy from the ground through the kinetic chain. Optimized lower-body power may lessen the magnitude of forces on the upper extremity. Insufficient lower-body power may create a greater risk of upper-body injury. Lower-body power and its relationship to ball velocity have been minimally investigated, yet some research points to a correlation between jumping ability and fastball velocity. Because pitching is unilateral, practitioners should consider unilateral jumps to determine the extent of bilateral asymmetry or stride to drive leg differences that can guide training to remediate deficiencies. The purposes of this brief review are to (a) examine factors that influence vertical jump performance among baseball players, (b) examine research on pitching multidirectional GRFs, and (c) examine literature concerning jump performances to baseball pitching performance. Collectively, this review can assist coaches and practitioners in lower-body power testing and training for baseball pitchers.

Effects of 700 and 3500 MHz 5G radiofrequency exposure on developing zebrafish embryos

Telecommunications industries are rapidly deploying the fifth generation (5G) spectrum and there is public concern about the safety and health impacts of this type of Radio Frequency Radiation (RFR), in part because of the lack of comparable scientific evidence. In this study we have used a validated commercially available setting producing a uniform field to expose zebrafish embryos (ZFe) to unmodulated 700 and 3500 MHz frequencies. We have combined a battery of toxicity, developmental and behavioral assays to further explore potential RFR effects. Our neurobehavioral profiles include a tail coiling assay, a light/dark activity assay, two thigmotaxis anxiety assays (auditory and visual stimuli), and a startle response - habituation assay in response to auditory stimuli. ZFe were exposed for 1 and 4 h during the blastula period of development and endpoints evaluated up to 120 hours post fertilization (hpf). Our results show no effects on mortality, hatching or body length. However, we have demonstrated specific organ morphological effects, and behavioral effects in activity, anxiety-like behavior, and habituation that lasted in larvae exposed during the early embryonic period. A decrease in acetylcholinesterase activity was also observed and could explain some of the observed behavioral alterations. Interestingly, effects were more pronounced in ZFe exposed to the 700 MHz frequency, and especially for the 4 h exposure period. In addition, we have demonstrated that our exposure setup is robust, flexible with regard to frequency and power testing, and highly comparable. Future work will include exposure of ZFe to 5G modulated signals for different time periods to better understand the potential health effects of novel 5G RFR.

Spatial-extent inference for testing variance components in reliability and heritability studies

Abstract Clusterwise inference is a popular approach in neuroimaging to increase sensitivity, but most existing methods are currently restricted to the General Linear Model (GLM) for testing mean parameters. Statistical methods for testing variance components, which are critical in neuroimaging studies that involve estimation of narrow-sense heritability or test-retest reliability, are underdeveloped due to methodological and computational challenges, which would potentially lead to low power. We propose a fast and powerful test for variance components called CLEAN-V (CLEAN for testing Variance components). CLEAN-V models the global spatial dependence structure of imaging data and computes a locally powerful variance component test statistic by data-adaptively pooling neighborhood information. Correction for multiple comparisons is achieved by permutations to control family-wise error rate (FWER). Through analysis of task-functional magnetic resonance imaging (fMRI) data from the Human Connectome Project across five tasks and comprehensive data-driven simulations, we show that CLEAN-V outperforms existing methods in detecting test-retest reliability and narrow-sense heritability with significantly improved power, with the detected areas aligning with activation maps. The computational efficiency of CLEAN-V also speaks of its practical utility, and it is available as an R package.

Assessment of inter-individual variability in hamstring muscle recovery after a sport-specific sprint training in women and men.

Background: Hamstring muscles are most affected by multiple sprint-based sports as a result of muscle strain during sprinting, leading to reduced performance and increased risk of injury. Therefore, the purpose of the study was to assess inter-individual variability in hamstrings recovery after a sport-specific repeated-sprint training (RST), through sprint-specific markers of muscle recovery and associated muscle damage biomarkers in women and men. Methods: Healthy females (n = 14) and males (n = 15) underwent 10 repeated 40-m sprints with a 3-min rest pause between each repetition. Force-generating capacity (FGC) by the 90° hip :20° knee test and range of motion Jurdan test, together with serum biomarkers [sarcomeric mitochondrial creatine kinase (sMtCK), oxidative stress, irisin] were tested at baseline and 24-, 48- and 72-h post-exercise through a repeated measures design. Participants were classified according to FGC loss into high responders (HR) and low responders (LR). Results: 21 individuals (10 females, 11 males) were classified as HR (FGC loss >20% and recovery >48h), while 8 individuals (4 females, 4 males) were classified as LR. HR individuals showed unrecovered maximal voluntary isometric contraction (MVIC) torque until 72h post-training (p = 0.003, np 2 = 0.170), whereas only HR males showed decreased range of motion (p = 0.026, np 2 = 0.116). HR individuals also showed increased sMtCK (p = 0.016, np 2 = 0.128), oxidative stress (p = 0.038, np 2 = 0.106) and irisin (p = 0.019, np 2 = 0.123). Conclusion: There is inter-individual variability in the muscular response to a sport-specific RST, identifiable by MVIC torque assessment. The findings support that the 90° hip :20° knee test is a powerful indirect test to screen hamstrings recovery in both women and men, in a cost-effective way. However, the Jurdan test might not be able to monitor hamstrings recovery in sportswomen after RST. Decreases in muscle capacity are linked to damage to muscle sarcolemma and mitochondria until 72h post-exercise. Overall, 72h will not be adequate time to restore hamstrings structure and function after a sport-specific RST in both female and male responders.

Validity and reliability of linear encoder muscle power testing in persons with Parkinson's disease

Objective To investigate the construct validity ON medication and the reliability both ON and OFF medication of linear encoder muscle power testing in persons with Parkinson's disease (pwPD). Design A study using baseline data from one randomized controlled trial (study 1) and one cohort study (study 2). Setting University exercise lab. Participants Study 1: 35 healthy controls and 70 pwPD. Study 2: 20 pwPD. Intervention Study 1: baseline data. Study 2: 4 chair rise tests (2 ON and 2 OFF medication), in a randomized order, separated by 4 to 16 days. Main measures Linear encoder data were collected from a chair rise test. Known groups validity and convergent validity (i.e., construct validity) were assessed by comparing peak power between pwPD and healthy controls and associations between peak power and functional performance (i.e., 6-Min Walk Test, Timed Up and Go Test, Six-Spot Step Test), respectively. Reliability was assessed as day-to-day variation and by intraclass correlation coefficients. Results Peak power was comparable between pwPD and healthy controls (−7.2%, p = 0.17), but lower in moderately impaired pwPD compared to mildly impaired pwPD (−27%, p < 0.01) and healthy controls (−23%, p < 0.01). Moderate to strong associations were observed between peak power and functional performance (r2 = 0.44–0.51). Day-to-day variation ON and OFF medication were 1.0 and 1.3 W/kg, respectively, while intraclass correlation coefficients were 0.95 (0.87;0.98) and 0.93 (0.82;0.97), respectively. Conclusion Linear encoder muscle power testing shows inconsistent known groups validity, acceptable convergent validity ON medication, and excellent day-to-day reliability ON and OFF medication in pwPD.

Weighted Hazard Ratio Estimation for Delayed and Diminishing Treatment Effect

Nonproportional hazards (NPH) have been observed in confirmatory clinical trials with time to event outcomes. Under NPH, the hazard ratio does not stay constant over time and the log rank test is no longer the most powerful test. The weighted log rank test (WLRT) has been introduced to deal with the presence of nonproportionality. We focus our attention on the WLRT and the complementary Cox model based on time varying treatment effect proposed by Lin and León. We investigate whether the proposed weighted hazard ratio (WHR) approach is unbiased in scenarios where the WLRT statistic is the most powerful test. In the diminishing treatment effect scenario where the WLRT statistic would be most optimal, the time varying treatment effect estimated by the Cox model estimates the treatment effect very close to the true one. However, when the true hazard ratio is large the proposed model overestimates the treatment effect and the treatment profile over time. In the delayed treatment scenario, the estimated treatment effect profile over time is typically close to the true profile. For both scenarios, we have demonstrated analytically that the hazard ratio functions are approximately equal under small treatment effects. When the assumed rate of how quickly the treatment effect profile is diminishing or delaying differs in the analysis from that in the true data generating mechanism, the estimated hazard ratio profile from the WHR approach is biased. Since in practice the true HR time profile may differ from that assumed in the WHR analysis, it may be preferable to use alternative approaches for effect estimation.

Process evaluation of the 90-90-90 targets of surge project in Addis Ababa, Ethiopia: a case study evaluation.

Human Immunodeficiency Virus (HIV) is a major public health problem that continues to pose an enormous challenge to mankind's survival worldwide. In urban Ethiopia, the HIV prevalence among adults aged 15-49 years is 2.9%, while in Addis Ababa, it is 3.4%. To take the edge off, the Ethiopian government has been implementing the 90-90-90 strategy also known as the surge project, in urban cities. However, the implementation of the program has not been evaluated. Thus, we evaluated the process of the 90-90-90 targets of the surge project in Addis Ababa, Ethiopia. We conducted a case study with concurrent mixed-methods evaluation. We used indicator-driven evaluation dimensions -availability and accommodation dimensions from the health services access and compliance and fidelity from implementation fidelity frameworks to test the program process theory with a total of 52 indicators. We interviewed a total of 419 clients and 210 healthcare providers and reviewed 417 clients' cards and 17 registries. We also conducted 30 key informant interviews and resource inventory. A binary logistic regression analysis was done to identify factors associated with clients' satisfaction. We transcribed and translated the qualitative data and analysed thematically. Finally, we judged the overall process of the surge project based on the pre-seated judgmental criteria as; needs urgent improvement, needs improvement and well implemented. We found that 90% of the project process was as per the program process theory measured by the availability of resources (95.8%), compliance (88.0%), fidelity (84.7%), and accommodation of services (89.3%). We found a shortage of human power, test kits, and viral load testing machines. The commitment of health care providers, provider-client interaction, and clients' satisfaction with the service at card rooms were found to be poor. Moreover, being aged 15-24, being married and government government-employed were negatively associated with clients' satisfaction with antiretroviral therapy services. The process of the surge project needs improvement. Moreover, the achievements of the first two 90-90 targets were poor. Therefore, implementers need to take intensified action for the availability of resources and to improve the commitment of healthcare providers through refreshment training.

Integrating VR into Power Testing: Opportunities and Challenges

Integrating VR into Power Testing: Opportunities and Challenges

MORE POWERFUL HSIC-BASED INDEPENDENCE TESTS, EXTENSION TO SPACE-FILLING DESIGNS AND FUNCTIONAL DATA

The Hilbert-Schmidt independence criterion (HSIC) is a dependence measure based on reproducing kernel Hilbert spaces. This measure can be used for the global sensitivity analysis of numerical simulators whose objective is to identify the most influential inputs on the output(s) of the code. For this purpose, HSIC-based sensitivity measures and independence tests can be used for the ranking and screening of inputs, respectively. In this framework, this work proposes several improvements in the use of HSIC to increase their application spectrum and make the associated independence tests more powerful. First, we introduce a new method to perform the tests in a non-asymptotic framework. This method is much less central-processing-time expensive than the one based on permutation, while remaining as efficient. Then, the use of HSIC-based independence tests is extended to the case of some space-filling designs, where the independent and identically distributed condition of the observations is lifted. For this, a new procedure based on conditional randomization test is used. In addition, we also propose a more powerful test that relies on a well-chosen parameterization of the HSIC statistics: the kernel bandwidth parameter is optimized instead of the standard choices. Numerical studies are performed to assess the efficiency of these procedures and compare it to existing tests in the literature. Finally, HSIC-based indices for functional outputs are defined: they rely on appropriate and relevant kernels for this type of data. Illustrations are provided on temporal outputs of an analytical function and a compartmental epidemiological model.

Equivalence testing for multiple groups

SummaryTesting for equivalence, rather than testing for a difference, is an important component of some scientific studies. While the focus of the existing literature is on comparing two groups for equivalence, real‐world applications arise regularly that require testing across more than two groups. This paper reviews the existing approaches for testing across multiple groups and proposes a novel framework for multigroup equivalence testing under a Bayesian paradigm. This approach allows for a more scientifically meaningful definition of the equivalence margin and a more powerful test than the few existing alternatives. This approach also allows a new definition of equivalence based on future differences.

Effect of 1-Week Weight Loss While Maintaining Total Body Water on Jump Performance.

Jumping performance is influenced by body composition and excess fat mass impairs performance. Maintaining optimal fat mass and fat-free mass (FFM) is crucial for enhancing jump height. However, there is limited evidence on short-term weight loss programs that reduce fat mass without water restriction and their effects on muscle function and jumping performance. This study aimed to clarify the effects of a 1-week weight loss program on jumping height and muscle function of volleyball players. The weight loss group engaged in two 40 min slow-paced jogging sessions in addition to their daily training routine. Energy intake was restricted without limitations on water intake. Total body water and body composition using the deuterium dilution method, muscle strength, and jump height before and after 1 week were evaluated for those in the weight loss and control groups. Body mass was significantly reduced in the weight loss group (-2.7 ± 1.3%, p < 0.05) with a significant reduction in fat mass (-17.7 ± 10.7%, p < 0.05). Meanwhile, there were no significant changes in total body water or FFM. Muscle strength and power tests indicated no significant differences between the groups; no notable differences were observed in handgrip strength or knee extension torque. The height of a single vertical and continuous jump remained consistent pre- and postintervention in the control group. In the weight loss group, although the height of a single vertical jump exhibited a slight decline postintervention, the height of a continuous jump displayed no significant changes. The short-term weight loss program significantly reduced fat mass without compromising muscle function, which is crucial for sports performance. These findings may benefit other athletes who require fat mass reduction while maintaining muscle function and help create new programs during specific training phases.

Lower Extremity Asymmetry Values Derived From Multiple Strength Testing Modes Are Associated With Perceived Functional Capabilities Among University Athletes.

Background: Muscle strength asymmetry and athlete introspective measures are associated with musculoskeletal (MSK) sport injury and reinjury. However, the interrelationship between mechanical and subjective measures of concentric and eccentric limb function needs further exploration. This includes investigating if an athlete's perception of their overall MSK function influences limb asymmetry across different testing modalities. Objectives: To (i) explore the interrelationship between mechanical and subjective measures of lower limb function in university athletes and (ii) compare the consistency in interlimb strength asymmetries across different strength tests in groups of athletes with good, fair, and poor perceived limb function. Methods: University athletes (n = 175; n = 87 females) from six sports completed four tests of muscle strength, power, and plyometric function along with an assessment of perceived limb function using the Sport Fitness Index (SFI). Participants were categorized into high (GOODSFI), fair (FAIRSFI), and poor (POORSFI) perceived overall MSK function (perceived function) groups. Strength asymmetry indexes evaluated interlimb differences in concentric and eccentric maximal strength, countermovement jump (CMJ) impulse, unilateral CMJ height, and reactive strength index in unilateral repeat hop testing. Cumulative link mixed-effects models assessed the relationship between strength asymmetries and perceived limb function. Results: The POORSFI group showed increased asymmetry in concentric strength testing (p = 0.022), more consistent interlimb asymmetries (p < 0.001), and reduced overall muscle strength compared to the GOODSFI group. Conclusion: Higher interlimb asymmetry in maximal concentric strength measures along with reduced muscle strength was found in the POORSFI group compared to the GOODSFI group. The POORSFI group also showed greater consistency in muscle strength asymmetry derived across different tasks.

Antioxidant Activities of Steviol Glycosides from Moroccan Cultivated Stevia Rebaudiana Bertoni Leaves: An In Vitro Study

This study explores the antioxidant potential of three steviol glycosides isolated from Stevia Rebaudiana Bertoni leaves acclimatized in Morocco. Pure compounds were isolated and characterized by column chromatography, and their antioxidant activities were assessed using Ferric Reducing Antioxidant Power (FRAP) and Total Antioxidant Capacity (TAC) tests. The process of soxhlet extraction followed by column purification revealed three steviol glycosides with the following yields: steviolbioside (0.26%), rebaudioside-A (0.63%), and stevioside which exhibited the highest abundance (1.47%). Antioxidant activity tests showed that the compounds exhibited remarkable antioxidant properties, particularly in TAC test of 69.54, 72.32, and 51.6 mg AAE/1gDM for stevioside, steviolbioside, and rebaudioside-A respectively.

Analysis of the Effect of the Addition of Aluminum Powder on Polyester-Glass Composite Properties in Tensile and Hardness Test

The study aimed to analyse the influence of aluminum powder on the mechanical properties of polyester-glass composites. Composite materials were made of glass fibres with random fibre direction and polyester resin with the addition of aluminum powder as a filler. The strength parameters of materials obtained during the static tensile test and hardness test were compared. The results were subjected to statistical analysis, taking into account the change in the amount of filler, microstructure was also observed using optical microscopy. An analysis of the results showed that the addition of aluminum powder amounting to 2% of the weight of the composites reduces their hardness and, at the same time, the longitudinal modulus of elasticity.The addition of aluminum powder amounting to 5% and 10% of the weight of the composites increased the hardness of the composites while reducing the Young's modulus. The values of hardness measurements were subjected to statistical analyses at significance level α = 95. The Shapiro-Wilk test confirmed that the hardness variables for all tested samples were in normal distributions, and therefore the most powerful parametric tests were used to test the differences. Using the Student's t-test, it was confirmed that between pairs of variables in configurations: a standard sample with a modified sample, for all tested samples there are significant statistical differences in the distributions of hardness values. Studies have shown that the modification of the mechanical and strength properties of composite materials, through the use of an aluminum filler, makes it possible to obtain materials with variable parameters that can be useful and attractive in many new areas, depending on the application and user requirements.

Biosynthesis and characterization of silver nanoparticles using polysaccharides from Caulerpa racemosa and evaluation of their antioxidant, antibacterial, and anticancer activities

In recent years, using biological materials to synthesize metallic nanoparticles has emerged as an efficient and cost-effective approach. This work synthesized silver nanoparticles (AgNPs) from Caulerpa racemosa (Cr) - Polysaccharide (Ps). UV–vis spectroscopy examined the synthesised Cr-Ps-AgNPs, revealing a colour shift and a surface plasmon resonance peak at 450 nm. The Fourier transform infrared spectroscopy is used to detect functional groups within the polysaccharide and to investigate nanoparticle interactions. Scanning Electron Microscopy revealed that the biosynthesized Cr-AgNPs varied in size from 32 to 77 nm. X-ray diffraction confirmed that the Cr-Ps-AgNPs were crystalline. Also, dynamic light scattering showed that the Cr-Ps-AgNPs particles, which were biosynthesized nanoparticles, had a size distribution that was polydisperse, with an average diameter of 42.8 nm. In a dose-dependent manner, the biosynthesized Cr-Ps-AgNPs demonstrate high antioxidant activity in the DPPH, reducing power, and total antioxidant scavenging tests. The antibacterial activity of Cr-Ps-AgNPs against Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus pyogenes was assessed using an agar well diffusion test, which revealed dose-dependent activity. The cytotoxicity investigation showed a dose-dependent activity against breast cancer cells (MCF-7), with an inhibitory concentration (IC50) of 38 μg/mL. The results of this study show that synthesised Cr-Ps-AgNPs exhibit antioxidant, antibacterial, and anticancer properties.

Robust and powerful gene-environment interaction tests using rare genetic variants in case-control studies

Robust and powerful gene-environment interaction tests using rare genetic variants in case-control studies

Antioxidant Effect of Levetiracetam and Brivaracetam Acting on Presynaptic SV2A Receptors: An In-vitro Study

Introduction: Epilepsy is a serious psychological condition associated with social stigma, psychiatric co-morbidity, and a high economic burden. It is pertinent to develop novel treatment methods given the ever-evolving nature of the disease. Recently, various newer Antiepileptic Drugs (AEDs) have been under study, among which a newer targeted modality consists of SV2A receptors. Aim: To compare the antioxidant properties or free radical scavenging activity of the newer heterogeneous AEDs acting on the SV2A receptors, namely Levetiracetam (LEV) and Brivaracetam (BRV). Materials and Methods: This in-vitro study was conducted at Department of Pharmacology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India from July 2021 to August 2021. The study evaluated the antioxidant properties of LEV and BRV using various assays such as the Ferric Reducing Antioxidant Power (FRAP) test, DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, Nitric Oxide (NO) radical scavenging assay, Superoxide Dismutase activity (SOD), and catalase activity. The obtained results were expressed using specific formulas related to the absorbance of the respective chemicals, along with the percentage of inhibition, and have been tabulated in Microsoft excel Sheet Version 16.16.27. Halfmaximal Inhibitory Concentration (IC50) values were calculated using scatter plot graphs. Results: The FRAP values for LEV were reported to be significantly higher compared to BRV at concentrations of 20, 40, 60, 80 μg/mL, while at 100 μg/mL, BRV showed better ferric reducing activity. Although both drugs exhibited antioxidant activity, the results clearly identified LEV as a better NO radical scavenger, with a percentage of inhibition reaching up to 80.52%. During the SOD assay, the percentage inhibition of superoxide generation by LEV was found to be 99.02%, while that of BRV was 97.07% at a concentration of 100 μg/mL. LEV (0.573) also showed a higher degradation of H2O2 per minute than BRV (0.065) at a concentration of 100 μg/mL. Conclusion: The results showed that both drugs, BRV and LEV, exhibited significant antioxidant capacity. However, LEV demonstrated increased antioxidant potency and efficacy compared to BRV.

On the issue of diagnostic accuracy of methods for analyzing the parameters of regular astigmatism

This study evaluates the diagnostic accuracy of various methods for measuring the parameters of regular astigmatism. The study included 83 patients (122 eyes) with regular astigmatism exceeding 1.0 D. Three groups were formed depending on the type of astigmatism. Spherical and cylindrical (power and axis) components of refraction were determined using automatic refractometry. The results were refined with subjective tests: power and axis tests with a cross-cylinder. The criterion for diagnostic accuracy was the level of corrected visual acuity. To assess the impact of cylinder position on visual acuity, discrete deviations of the axis of trial astigmatic lenses from the correct position (determined based on subjective tests) were modeled at 5, 10, and 15 degrees in both clockwise and counterclockwise directions. In the overall sample of observations, coincidence of results was found only in one-third of cases, with a tendency for discrepancies in data between the two methods in nearly 70% of cases. Statistical processing revealed significant differences only in the magnitude of the cylinder in the group with against-the-rule astigmatism (p<0.0005). An increase in maximum visual acuity corrected based on subjective test data was noted. With a deviation of the cylinder axis from the correct position by 10-15 degrees, regardless of the type of astigmatism, a significant tendency for a decrease in visual acuity was identified. At the same time, with a deviation of the cylinder axis within 5 degrees, a significant decrease in visual acuity was noted only in with-the-rule astigmatism and counterclockwise deviation. To achieve maximum visual acuity in the correction of regular astigmatism, objective method data must be refined with subjective tests. The results of modeling the deviation of the axis of the corrective lens from the proper position can be considered when evaluating the functional outcomes of TIOL implantation.

Effect of duration and infection control barriers of light curing unit on hardness of Bulk Fill composite resin.

This study aimed to investigate the impact of the duration of light curing unit (LCU) usage and the use of infection control barriers on the hardness of Bulk Fill composite resin after curing. The hypotheses were that extended usage of the LCU would not reduces its output power and resin hardness, and that the presence of polyethylene film barriers exacerbates the reduction in resin hardness. Based on the absence or presence of polyethylene film (PE) and the number of layers used, a 3M LED curing light (EliparTM DeepCure-S; 3M ESPE, St Paul, MN, USA) was divided into three groups: PE0, PE1, and PE3. The curing light was used 30 times daily for 20 s per exposure, at frequencies of 0, 6, and 12 months. Maximum output power tests were conducted for each group of curing lights. Custom-made plastic modules were used to stack Bulk Fill composite resin (Filtek Bulk Fill Posterior Restorative; 3M ESPE) to a thickness of 4 mm. Each group of curing lights was used to cure the modules in a direct contact manner for 20 s. Vickers hardness measurements were taken at the top and bottom surfaces of the resin specimens using a digital microhardness tester. A one-way or two-way ANOVA analyzed the power of LCUs, Vickers hardness of Bulk Fill composite resin, and hardness decrease percentage across groups. Pairwise comparisons used the Tukey test (α = 0.05). As the duration of usage increased, both the power of the curing light and the hardness of the resin significantly decreased. Significant differences were observed in power and resin hardness among the PE0, PE1, and PE3 groups. When the duration of usage was 6 months or less, only multi-layered PE films led to a significant increase in the percentage decrease of hardness of cured resin from top to bottom. However, at 12 months, both single-layer and multi-layered PE films resulted in a significant increase in the percentage decrease of hardness of cured resin from top to bottom. The output power of the light curing unit decreases with prolonged usage, thereby failing to meet the curing requirements of Bulk Fill composite resin. The use of single-layer PE as an infection control barrier is recommended.