Test Procedure Research Articles

Comparing two hazard curves when there is a treatment time-lag effect.

In cancer and other medical studies, time-to-event (eg, death) data are common. One major task to analyze time-to-event (or survival) data is usually to compare two medical interventions (eg, a treatment and a control) regarding their effect on patients' hazard to have the event in concern. In such cases, we need to compare two hazard curves of the two related patient groups. In practice, a medical treatment often has a time-lag effect, that is, the treatment effect can only be observed after a time period since the treatment is applied. In such cases, the two hazard curves would be similar in an initial time period, and the traditional testing procedures, such as the log-rank test, would be ineffective in detecting the treatment effect because the similarity between the two hazard curves in the initial time period would attenuate the difference between the two hazard curves that is reflected in the related testing statistics. In this paper, we suggest a new method for comparing two hazard curves when there is a potential treatment time-lag effect based on a weighted log-rank test with a flexible weighting scheme. The new method is shown to be more effective than some representative existing methods in various cases when a treatment time-lag effect is present.

On-board equipment testing procedure for the effects of electrostatic discharges

On-board equipment testing procedure for the effects of electrostatic discharges

Bootstrap test procedure for variance components in nonlinear mixed effects models in the presence of nuisance parameters and a singular Fisher information matrix

Bootstrap test procedure for variance components in nonlinear mixed effects models in the presence of nuisance parameters and a singular Fisher information matrix

Inference for Dependent Data with Learned Clusters

Abstract This paper presents and analyzes an approach to cluster-based inference for dependent data. The primary setting considered here is with spatially indexed data in which the dependence structure of observed random variables is characterized by a known, observed dissimilarity measure over spatial indices. Observations are partitioned into clusters with the use of an unsupervised clustering algorithm applied to the dissimilarity measure. Once the partition into clusters is learned, a cluster-based inference procedure is applied to a statistical hypothesis testing procedure. The procedure proposed in the paper allows the number of clusters to depend on the data, which gives researchers a principled method for choosing an appropriate clustering level. The paper gives conditions under which the proposed procedure asymptotically attains correct size. A simulation study shows that the proposed procedure attains near nominal size in finite samples in a variety of statistical testing problems with dependent data.

Comparison of available methods to evaluate cefiderocol susceptibility in Acinetobacter spp

Recently, considerable uncertainty has arisen concerning the appropriate susceptibility testing for cefiderocol in gram-negative bacilli, particularly in the context of its application to Acinetobacter spp. The optimal method for assessing the susceptibility levels of Acinetobacter spp. to cefiderocol remains a subject of debate due to substantial disparities observed in the values obtained through various testing procedures. This study employed four minimum inhibitory concentration (MIC) methodologies and the disk diffusion to assess the susceptibility of twenty-seven carbapenem resistant (CR)-Acinetobacter strains to cefiderocol. The results from our study reveal significant variations in the minimum inhibitory concentration (MIC) values obtained with the different methods and in the level of agreement in interpretation categories between the different MIC methods and the disk diffusion test. Among the MIC methods, there was relatively more consistency in reporting the interpretation categories. For European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, the categorical agreement (CA) for MIC methods ranged between 66.7 and 81.5%. On the other hand, the essential agreement (EA) values were as low as 18.5–29.6%. The CA between MIC methods and disk diffusion was 81.5%. These results emphasize the need for a reliable, accurate, and clinically validated methodology to effectively assess the susceptibility of Acinetobacter spp. to cefiderocol. The wide variability observed in our study highlights the importance of standardizing the susceptibility testing process for cefiderocol to ensure consistent and reliable results for clinical decision-making.

Generating linear, semidefinite, and second-order cone optimization problems for numerical experiments

The numerical performance of algorithms can be studied using test sets or procedures that generate such problems. This paper proposes various methods for generating linear, semidefinite, and second-order cone optimization problems. Specifically, we are interested in problem instances requiring a known optimal solution, a known optimal partition, a specific interior solution, or all these together. In the proposed problem generators, different characteristics of optimization problems, including dimension, size, condition number, degeneracy, optimal partition, and sparsity, can be chosen to facilitate comprehensive computational experiments. We also develop procedures to generate instances with a maximally complementary optimal solution with a predetermined optimal partition to generate challenging semidefinite and second-order cone optimization problems. Generated instances enable us to evaluate efficient interior-point methods for conic optimization problems.

Efficiencies of Thermophilic Bacteria Species in Degrading Biodegradable Low-density Polyethylene Mixtures in Aquatic Ecosystems

The study examined the efficiencies of bacteria thermophiles responsible for the depolymerization of biodegradable Low-Density Polyethylene (LDPE) blends in two aquatic environments to suggest model bacteria species that could be used for reducing the accumulation of single-use LDPE in both marine and freshwater ecosystems. Each of the biodegradable LDPE, polyethylene, and cellulose was placed in respirometry jars filled with 500 mls of the freshwater and marine water respectively in a randomized design of 4 by 2 by 3 following the American Standard Testing and Materials (ASTM) procedure. To identify the bacteria species, bacterial isolation was done using pour plate and streak methods. The bacteria species were identified by morphological, biochemical, and molecular methods. The thermophilic bacteria species were confirmed by sequencing to be Bacillus cereus, Pseudomonas species among others. The results revealed that the bacteria isolates on LDPE were responsible for the biodegradation processes of the LDPE. This study concluded that Bacillus cereus and Pseudomonas species have the bioremediation potentials to break down single-use biodegradable Low-Density Polyethylene (LDPE) in aquatic environments within six (6) months.

Lumbar and Cervical Concurrent Muscle Activity Analysis During Hamstring Length Testing to Design a Customized Treatment Plan: An Observational Cross-Sectional Study.

Hamstring length plays a significant role in a spectrum of clinical entities, from injury prevention and gait dysfunction to posture correction. Evidence suggests that the prevalence of hamstring tightness (HT)/reduced length is increasing. Despite the number of available tests and treatment protocols, HT is still a functional diagnosis. This study's primary goal is to evaluate concurrent muscle (CM) usage during these testing procedures to design a unique, customized treatment protocol. The study was conducted in two stages. In phase 1, Active Straight Leg Raise (ASLR), Active Total Knee Extension (ATKE), and Active Seated Total Knee Extension (ASTKE) were carried out. Next, two pressure gauges (PGs) were placed to align with the natural lumbar and cervical curvatures while testing ASLR and ATKE. After analyzing the results for pressure gauge placement, phase 2 data were collected for tests ASLR and ATKE with PG. The results of ASLR and ATKE, both with and without PG, indicate a high prevalence rate, whereas the results of ASTKE show no prevalence. Changes in the PG values indicate CM usage. Dichotomization revealed that participants with normal test scores (non-HT group) had increased usage of CM work. Positive and negative changes in PG indicate the involved CM group. In regular practice, most healthcare professionals and fitness trainers prefer ASTKE due to the ease of the testing procedure. Directing co-professionals on their choice of tests is challenging, whereas providing knowledge about CM use paves the way for creating customized treatment plans.

Accommodative Strategies and School Administrator’s Managerial Effectiveness in Public Secondary Schools in Akwa Ibom South-South Senatorial District

This study investigated the relationship between Accommodative Strategies and School Administrator’s Managerial effectiveness in Public Secondary Schools in Akwa Ibom South-south Senatorial district. In order to achieve the purpose of this study three purposes, three research questions were raise and three null hypotheses were formulated to guide the study. The sub-variables of the study which were self-regulation, emotional adjustment, and communication adjustment and administrators’ managerial effectiveness were reviewed under conceptual framework and empirical studies, the sample size consisted of 77 respondents representing the population of 95 drawn using simple random sampling technique. Data were collected using a structured closed ended questionnaire title, Accommodative Strategies Questionnaire (ASQ) and Administrators Managerial Effectiveness Questionnaire (AMEQ). The reliability of the instrument was established by using the data from trial testing procedure which yielded .76, which showed that the instrument was reliable to be used in the study. Research questions and hypotheses were answered using PPMC (Pearson Product Moment Correlation) analyses at .05 level of significant. The findings of the study revealed that accommodative strategies such as self-regulation, emotional adjustment and communication adjustment relate significantly to the school administrators’ managerial effectiveness in secondary school students in Akwa Ibom South-South senatorial district. The findings of this study would contribute to knowledge in the sense that, researchers in different places and times would likely used as reference document conducted further studies on related issue.

Adding experimental treatment arms to multi-arm multi-stage platform trials in progress.

Multi-arm multi-stage (MAMS) platform trials efficiently compare several treatments with a common control arm. Crucially MAMS designs allow for adjustment for multiplicity if required. If for example, the active treatment arms in a clinical trial relate to different dose levels or different routes of administration of a drug, the strict control of the family-wise error rate (FWER) is paramount. Suppose a further treatment becomes available, it is desirable to add this to the trial already in progress; to access both the practical and statistical benefits of the MAMS design. In any setting where control of the error rate is required, we must add corresponding hypotheses without compromising the validity of the testing procedure.To strongly control the FWER, MAMS designs use pre-planned decision rules that determine the recruitment of the next stage of the trial based on the available data. The addition of a treatment arm presents an unplanned change to the design that we must account for in the testing procedure. We demonstrate the use of the conditional error approach to add hypotheses to any testing procedure that strongly controls the FWER. We use this framework to add treatments to a MAMS trial in progress. Simulations illustrate the possible characteristics of such procedures.

Familywise error for multiple time-to-event endpoints in a group sequential design.

We investigate the familywise error rate (FWER) for time-to-event endpoints evaluated using a group sequential design with a hierarchical testing procedure for secondary endpoints. We show that, in this setup, the correlation between the log-rank test statistics at interim and at end of study is not congruent with the canonical correlation derived for normal-distributed endpoints. We show, both theoretically and by simulation, that the correlation also depends on the level of censoring, the hazard rates of the endpoints, and the hazard ratio. To optimize operating characteristics in this complex scenario, we propose a simulation-based method to assess the FWER which, better than the alpha-spending approach, can inform the choice of critical values for testing secondary endpoints.

The physical capabilities of national league female American Flag Football players

Flag Football is the fastest growing format of American Football and is a recent addition to the 2028 Olympics. The Flag format is a non-contact version of American Football, where tackles are made by removing flags from players hips. Activity profiles in the NFL (Sanchez et al., 2013, App Sci, 13:9278; Wellman et al., 2016, J Strength Cond Res, 30, 11–19) have highlighted the need for high levels of strength, power, and speed. Given the similarities within Flag, these physical capabilities may be equally applicable to Flag players. However, a lack of literature on the Flag format, and the paucity of research in female football, irrespective of format, exists. Therefore, the aim of this study was to explore the physical fitness capabilities of a national league Women’s Flag Football team. Fourteen participants (age 28 ± 5 years; stature 166 ± 8 cm; mass 79 ± 29 kg) from a national league Women’s Flag team took part in a physical fitness testing battery comprising; countermovement jump (CMJ), squat jump (SJ), broad jump (BJ), 20-yard sprint and shuttle, and the Isometric mid-thigh pull (IMTP). Participants were familiarised with testing procedures and initially completed a standardised warm-up. Mean and SD results from the jump assessments were as follows; CMJ jump height 25.1 ± 5.9 cm, peak power 39.1 ± 7.1 w/kg; SJ jump height 24.6 ± 6.3 cm, peak power 39.3 ± 6.6 w/kg; broad jump 1.89 ± 0.28 m. Absolute and relative peak force in the IMTP was 2201 ± 422 N and 30.1 ± 4.1 N/kg respectively. The Dynamic Strength Index (DSI) calculated from CMJ and IMTP peak force was 0.76 ± 0.12. Lastly, 20-yard sprint and shuttle times were 3.43 ± 0.28 and 5.36 ± 0.38 s respectively. Significant correlations were found between mean CMJ jump height and mean sprint time (p 0.001; r = −0.780), between mean CMJ jump height and mean shuttle time (p <.001; r −0.857), between mean BJ distance and mean shuttle time (p <0.01; r = 0.870) and between mean BJ distance and CMJ jump height (p <.001; r = −0.911). This study is the first of its kind to report the physical capabilities of female flag football players. The findings of this study may help develop the understanding of a growing and soon to be Olympic sport.

Development of sleepiness in professional truck drivers: Real-road testing for driver drowsiness and attention warning (DDAW) system evaluation.

All new vehicle types within the European Union must now be equipped with a driver drowsiness and attention warning system starting from 2022. The specific requirements for the test procedure necessary for type approval are defined in the Annex of EU Regulation C/2021/2639. The objectives of this study were to: (i) investigate how sleepiness develops in professional truck drivers under real-road driving conditions; and (ii) assess the feasibility of a test procedure for validating driver drowsiness and attention warning systems according to the EU regulation. Twenty-four professional truck drivers participated in the test. They drove for 180 km on a dual-lane motorway, first during daytime after a normal night's sleep and then at nighttime after being awake since early morning. The results showed higher sleepiness levels during nighttime driving compared with daytime, with a faster increase in sleepiness with distance driven, especially during the night. Psychomotor vigilance task results corroborated these findings. From a driver drowsiness and attention warning testing perspective, the study design with sleep-deprived drivers at night was successful in inducing the targeted sleepiness level of a Karolinska Sleepiness Scale score of ≥ 8. Many drivers who reported a Karolinska Sleepiness Scale ≥ 8 during the drives also acknowledged feeling sleepy in the post-drive questionnaire. Reaching high levels of sleepiness on real roads during daytime is more problematic, not the least from legal and ethical perspectives as higher traffic densities during the daytime lead to increased risks.

Brake Wear and Airborne Particle Mass Emissions from Passenger Car Brakes in Dynamometer Experiments Based on the Worldwide Harmonized Light-Duty Vehicle Test Procedure Brake Cycle

Brake wear particles, as the major component of non-exhaust particulate matter, are known to have different emissions, depending on the type of brake assembly and the specifications of the vehicle. In this study, brake wear and wear particle mass emissions were measured under realistic vehicle driving and full friction braking conditions using current commercial genuine brake assemblies. Although there were no significant differences in either PM10 or PM2.5 emissions between the different cooling air flow rates, brake wear decreased and ultrafine particle (PM0.12) emissions increased with the increase in the cooling air flow rate. Particle mass measurements were collected on filter media, allowing chemical composition analysis to identify the source of brake wear particle mass emissions. The iron concentration in the brake wear particles indicated that the main contribution was derived from disc wear. Using a systematic approach that measured brake wear and wear particle emissions, this study was able to characterize correlations with elemental compositions in brake friction materials, adding to our understanding of the mechanical phenomena of brake wear and wear particle emissions.

Strength of Composite Pressure Insulators for High Voltage Circuit Breakers: An Experimental and Numerical Investigation.

Glass fiber-reinforced composite cylinders, capable of withstanding internal pressure generated during service, are increasingly utilized as insulators in high voltage circuit breakers. Different testing procedures have been suggested by various standards to assess the pressure resistance of these components. Due to its simplicity and cost-effectiveness, the split-disk testing method is the most widely used for evaluating the hoop strength of pressure cylinders during the development and verification phases. However, the method presents several aspects, such as those related to the influence of specimen geometry and friction, which require further examination since they may impact the outcome of the experimental tests. The investigation, carried out by a combination of experimental testing and finite element analyses, shows that the friction between the specimen and the semi-disks has a noteworthy effect on the hoop load applied to the specimen. Almost constant load distributions along the hoop direction, representative of the real operating conditions in a pressurized cylinder, can be achieved via proper lubrication of the contact surfaces. Furthermore, FE analyses demonstrate that the notch geometry suggested by specific standards (short notch) is not capable of inducing a uniform strain distribution in the notched region. A different notch geometry (long notch) is proposed in the study to attain a more uniform strain field over the reduced area region. The experimental results indicate that the strength measured on the short notch specimens is higher than that determined on the long notch specimens, thus confirming the significant influence of strain distribution on the strength properties measured with the split-disk method.

A Microfluidic Chip-Based Automated System for Whole-Course Monitoring the Drug Responses of Organoids.

Tumor patients-derived organoids, as a promising preclinical prediction model, have been utilized to evaluate ex vivo drug responses for formulating optimal therapeutic strategies. Detecting adenosine triphosphate (ATP) has been widely used in existing organoid-based drug response tests. However, all commercial ATP detection kits containing the cell lysis procedure can only be applied for single time point ATP detection, resulting in the neglect of dynamic ATP variations in living cells. Meanwhile, due to the limited number of viable organoids from a single patient, it is impractical to exhaustively test all potential time points in search of optimal ones. In this work, a multifunctional microfluidic chip was developed to perform all procedures of organoid-based drug response tests, including establishment, culturing, drug treatment, and ATP monitoring of organoids. An ATP sensor was developed to facilitate the first successful attempt on whole-course monitoring the growth status of fragile organoids. To realize a clinically applicable automatic system for the drug testing of lung cancer, a microfluidic chip based automated system was developed to perform entire organoid-based drug response test, bridging the gap between laboratorial manipulation and clinical practices, as it outperformed previous methods by improving data repeatability, eliminating human error/sample loss, and more importantly, providing a more accurate and comprehensive evaluation of drug effects.

An in vitro technique to measure resistance to compression and kinking of endotracheal tubes

Background: During intraoperative care, ventilatory parameters including peak inflating pressure (PIP) and exhaled tidal volumes are continuously monitored to assess changes in respiratory resistance and compliance. Changes in these parameters, such as an increase in PIP or a decrease in the exhaled tidal volume, may indicate various pathologic processes that may require immediate attention to prevent inadequate ventilation resulting in hypoxemia or hypercarbia. A kinked endotracheal tube (ETT) may mimic other pathologic processes including bronchospasm, mainstem intubation, or ventilator malfunction. As newer ETTs are developed, a key factor in their design should be resistance to kinking or occlusion due to patient positioning. Methods: The current project developed and describes the process for using a repeatable in vitro mechanical test to determine resistance to kinking by an ETT. Results: The mechanical testing procedure can be used to determine the compression force and distance required to kink an ETT under different conditions including temperature. The force required to induce devastating kink failure was lower during heated testing conditions. The addition of airflow through the ETTs during compression testing confirms the occurrence of airway obstruction at approximately the same time a mechanical kink is observed on the force-versus-distance curves. Conclusions: These procedures may be used to characterize and evaluate ETT designs under in vitro conditions mimicking those in the clinical practice.

Optimized Design and Operation Control of Refrigerant Direct Cooling Thermal Management System for Power Battery

In order to solve the compatibility problem of lithium batteries thermal management and cabin comfort in electric vehicles, a refrigerant direct cooling thermal management system is designed in this article, which is expected to balance the temperature demands of entire vehicle at different driving conditions. A one‐dimensional model is established to investigate the system performance, whose accuracy has been verified by the testing bench of a prototype fixed with a 16‐battery module. By the aid of this model, the thermal characteristics of the battery pack and the passenger cabin are obtained, and the compressor speed as well as the valves are selected as control units by sensitivity analysis of the important components. Subsequently, detailed control strategies around the variable frequency of compress speed and switch regulation for the valves are proposed based on the temperature changes, torque, and operating power consumption of the system in different control modes. Under the test conditions of the global light‐duty vehicle test procedure, it is found that cabin temperature can be quickly stabilized about 26 °C under different ambient temperatures. Additionally, the battery pack can be effectively maintained within the safe operating temperature range of 20–40 °C.

The legal aspects of cybersecurity vulnerability disclosure: To the NIS 2 and beyond

This paper focuses on the legal aspects of responsible vulnerability disclosure, bug bounty programs and legal risks associated with their implementation in the Czech Republic. Firstly, the authors introduce the basics of vulnerability disclosure procedures, identify different organisational models, and identify risks that may arise on the part of the organisation launching the bug bounty program or the hackers participating in it. The identified risks are divided into those arising from civil law, administrative law, and criminal law. For each identified risk, the authors then propose appropriate technical, organisation or legal solutions that can be applied to eliminate or reduce these risks. Nevertheless, the authors identified two areas that cannot be sufficiently mitigated through existing tools and laws and are likely to require legislative intervention – the matter of safeguarding the anonymity of reporters through confidentiality, and the problematic ability to consent to the testing procedures by the public bodies.

Method for accelerated testing of wind turbine gearbox bearings based on frictional energy in the rolling contact

This paper investigates a method for a novel accelerated test procedure for rolling bearings in wind turbine gearboxes. Established test procedures e. g. highly accelerated lifetime tests (HALT) mainly reflect fatigue damage and not slip-induced damage patterns (e.g. smearing). A commonly used criterion to rate the severity of an operating point regarding slip-induced damage is the frictional energy. Frictional energy is introduced into the rolling contact as soon as there is a significant combination of simultaneously occurring slip and pressure. Up to now only critical thresholds for this criterion that must not be exceeded have been identified on small-scale component test rigs. However, the permissible amount and duration of overshoots of the critical threshold that lead to damage in the actual application are not understood yet. Therefore, the aim is to conduct tests on full-size test rigs in which frictional energy is applied until slip-induced damage occurs. In order to perform these tests in a reasonable time, it is essential to accelerate the test procedures. Thus, this paper introduces a method for accelerated test procedures based on frictional energy in the rolling contact. The requirement is that the same cumulated frictional energy as in field operation is applied in a shorter time on the test rig. A further requirement is that the frictional power in the accelerated test procedure never exceeds the maximum frictional power occurring in the field. This paper shows the theoretical background regarding frictional energy and the transfer to the test procedure.