Repeat Testing Research Articles

Performance evaluation of the Access HBsAg and Access HBsAg confirmatory assays on the DxI 9000 Access Immunoassay Analyzer

IntroductionThis study evaluated the clinical and analytical performances of the Access HBsAg and the Access HBsAg Confirmatory assays on the DxI 9000 Access Immunoassay Analyzer (Beckman Coulter, Inc.). Materials and methodsDiagnostic specificity and sensitivity of the Access HBsAg and Access HBsAg Confirmatory assays were evaluated by comparing the Access assays to the final HBsAg sample status determined using the Architect, PRISM, or Elecsys HBsAg assays, along with Architect or PRISM HBsAg Confirmatory assays. Imprecision, sensitivity on seroconversion panels, analytical sensitivity on WHO, and recognition of HBV variants were also evaluated. ResultsA total of 7534 samples were included in the analysis (6047 blood donors, 1032 hospitalized patients, 455 positive patients’ samples). Access HBsAg assay sensitivity and specificity were at 100.00% (99.19–100.0) and 99.92% (99.82–99.97), respectively. Sensitivity of Access HBsAg Confirmatory assay was 100.00% (99.21–100.0) on the 464 HBsAg positive samples. The use of a high positive algorithm for the Access HBsAg assay, wherein samples with S/CO ≥ 100.00 were considered positive without requiring repeat or confirmatory testing, was successfully evaluated with all 450 specimens with S/CO greater than 100.00 (sensitivity 100.00%; 99.19–100.0). Access HBsAg assay demonstrated good analytical performance, equivalent recognition of seroconversion panels compared to Architect assay, and an analytical sensitivity between 0.022 and 0.025 IU/mL. All HBV genotypes, subtypes and mutants were well detected without analytical sensitivity loss. ConclusionAccess HBsAg and Access HBsAg Confirmatory assays demonstrated robust performances. They provide low samples volume requirements and a simplified process, no systematic retesting for high positive samples.

The Effect of Nano-Hydrated Lime on the Durability of Hot Mix Asphalt

Recently, some of Iraq's newly constructed asphalt concrete pavements showed premature failures with significant negative impacts on roadway safety and the economy. Using Nano hydrated lime (NHL) in pavement construction could be one of the possible steps to improve pavement durability. This article discusses how NHL affects the durability of hot mix asphalt. NHL was added in two methods to the asphalt concrete mixture for the wearing course. The first is the dry method, i.e., on the aggregate, whereas the second is the wet addition method, i.e., to the bitumen. The percentages were tried for each additional method; 1, 2, and 3% by weight of aggregate for the dry method and 0.5, 1, and 1.5% by weight of asphalt concrete for the wet method. The optimum asphalt cement contents were evaluated using the Marshall procedure. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their durability properties, including moisture damage and permanent deformation. These properties have been evaluated using indirect tensile strength and uniaxial repeated loading tests. The results show that the NHL has improved the permanent deformation characteristics and resistance to moisture susceptibility.

Is there a right answer? A cross-laboratory study of concrete slabs

Commissioning a new acoustic test lab is a non-standardized process and validating test procedures and conditions is complicated by a lack of test samples with established performance. To aid in validating the results at the Maxxon Acoustics Lab, two concrete slabs were fabricated and tested in a Gage Repeatability and Reproducibility-style test design at Intertek Labs. After shipment from York, PA to Hamel, MN, mounting and edge conditions were established (as previously presented) at the Maxxon Labs, and the Gage R&R-style testing was replicated at the Maxxon Lab. The results indicate sources of variability between labs that can be attributed to the standard test methods, physical differences in reverberation rooms and test chamber design, and sample mounting conditions. In addition to validation of a single lab, the results have lessons for the interpretation of lab test results to improve isolation performance comparison across products and assemblies to inform architectural acoustic design.

International Diabetes Federation Position Statement on the 1-hour post-load plasma glucose for the diagnosis of intermediate hyperglycaemia and type 2 diabetes

Many individuals with intermediate hyperglycaemia (IH), including impaired fasting glycaemia (IFG) and impaired glucose tolerance (IGT), as presently defined, will progress to type 2 diabetes (T2D). There is confirmatory evidence that T2D can be prevented by lifestyle modification and/or medications, in people with IGT diagnosed by 2-h plasma glucose (PG) during a 75-gram oral glucose tolerance test (OGTT). Over the last 40 years, a wealth of epidemiological data has confirmed the superior value of 1-h plasma glucose (PG) over fasting PG (FPG), glycated haemoglobin (HbA1c) and 2-h PG in populations of different ethnicity, sex and age in predicting diabetes and associated complications including death. Given the relentlessly rising prevalence of diabetes, a more sensitive, practical method is needed to detect people with IH and T2D for early prevention or treatment in the often lengthy trajectory to T2D and its complications. The International Diabetes Federation (IDF) Position Statement reviews findings that the 1-h post-load PG ≥ 155 mg/dL (8.6 mmol/L) in people with normal glucose tolerance (NGT) during an OGTT is highly predictive for detecting progression to T2D, micro- and macrovascular complications, obstructive sleep apnoea, cystic fibrosis-related diabetes mellitus, metabolic dysfunction-associated steatotic liver disease, and mortality in individuals with risk factors. The 1-h PG of 209 mg/dL (11.6 mmol/L) is also diagnostic of T2D. Importantly, the 1-h PG cut points for diagnosing IH and T2D can be detected earlier than the recommended 2-h PG thresholds. Taken together, the 1-h PG provides an opportunity to avoid misclassification of glycaemic status if FPG or HbA1c alone are used. The 1-h PG also allows early detection of high-risk people for intervention to prevent progression to T2D which will benefit the sizeable and growing population of individuals at increased risk of T2D. Using a 1-h OGTT, subsequent to screening with a non-laboratory diabetes risk tool, and intervening early will favourably impact the global diabetes epidemic. Health services should consider developing a policy for screening for IH based on local human and technical resources. People with a 1-h PG ≥ 155 mg/dL (8.6 mmol/L) are considered to have IH and should be prescribed lifestyle intervention and referred to a diabetes prevention program. People with a 1-h PG ≥ 209 mg/dL (11.6 mmol/L) are considered to have T2D and should have a repeat test to confirm the diagnosis of T2D and then referred for further evaluation and treatment. The substantive data presented in the Position Statement provides strong evidence for redefining current diagnostic criteria for IH and T2D by adding the 1-h PG.

Immunoassay Testing of Alpha-Gal Specific Immunoglobulin-E: Data from a National Reference Laboratory.

Immunoassay measurements of serum alpha-gal (AG) specific IgE (sIgE) enable antibody detection and quantification with high sensitivity and specificity and are essential for AG syndrome diagnosis and patient management. We here present and analyze results from over 15 000 patient serum samples tested using the ImmunoCAP (Thermo/Phadia) assay. AG-sIgE levels and positivity rates were correlated to patient age, gender, geographic location, repeat testing results, sIgE levels to co-tested red meat whole allergen extracts, and Rocky Mountain spotted fever (RMSF) serology performed on a subset of patient samples. Of the tested samples, 36.7% contained detectable (>0.1 KUA/L) AG-sIgE. Antibody levels were higher in patients of older age, in samples submitted from lower midwestern and southern states, and during the June-December period of the year. Specific IgE to co-tested red meat whole allergens showed moderate to strong correlation to AG-sIgE and were of lower levels. Samples with positive RMSF IgG titers (≥1:64) were of overall higher AG-IgE levels. Findings are consistent with the role of lone star ticks in AG syndrome pathogenesis. Levels of measured sIgE to AG are higher than co-tested sIgE to red meat whole allergen, consistent with the improved diagnostic performance of component-resolved testing.

Research on the influence of heat release from cement hydration on the mechanical properties of casing

In order to study the influence of cement hydration heat release on the mechanical properties of casing, this paper calculates the wellbore temperature and pressure field based on the mathematical model of steady-state heat conduction of casing-cement ring-formation rock, establishes a mathematical model for the mechanical evaluation of cement hydration heat release and casing interaction, and performs finite element calculation and experimental simulation of the effect of cement hydration heat release on casing loss, and the results show that the results show: Along the axial direction of the wellbore, the maximum stress on the entire cement ring occurs in the lower position of the cement ring, and the maximum deformation on the casing occurs in the middle position. The axial stress variation range of the middle part of the casing is 50MPa, and the strain is 0.12%; The axial stress variation range of the outer ring is 235MPa, and the strain is 0.09%; The circumferential stress of the middle part varies from 500MPa to 0.255%. It is found that the stress and strain in the middle part of cement sheath are large, and yield is prone to occur. Under the action of cement hydration heat release, the long-axis elliptical deformation of (7.15∼31.8) mm occurs in the casing, that is, a large ovality is produced, which weakens the collapse strength of the casing. Two repeated tests showed that under the cement hydration heat release condition at the casing loss position, the temperature change of 60°C caused the increase of axial force of casing column and the increase of annular air pressure, which caused the non-uniform deformation of casing under the composite load of external extrusion and compression axial force.

Do serial troponins predict the need for cardiac evaluation in trauma patients after ground-level fall?

PurposeTroponin T levels are routinely checked in trauma patients after experiencing a ground-level fall to identify potential cardiac causes of syncope. An elevated initial troponin prompts serial testing until the...

Body composition in early pubescent children with obesity: effects following 1 year of nonintervention.

Little is known about whether body composition changes differently between children with and without obesity following 1 year of nonintervention. Therefore, we investigated body composition in early pubescent children (8-12 yr) with and without obesity before and after a period of 1 year of nonintervention. Early pubescent children (8-12 yr; Tanner stage ≤ 3) with (body mass index, BMI ≥ 95th percentile) and without obesity (15th < BMI < 85th percentile) were recruited. At baseline, 88 children (n = 25 without obesity) completed dual-energy X-ray absorptiometry imaging (DXA) for body composition measurements [%body fat, fat mass, fat-free mass (FFM)]. One year later, 47 participants (n = 15 without obesity) returned for repeat testing. The children without obesity were older (11.0 ± 1.0 vs. 10.0 ± 1.2 yr; means ± SD) (P = 0.013). There was no group difference in height, and both groups increased in height similarly after 1 year (147.7 ± 8.9 to 154.5 ± 9.2 cm without vs. 145.6 ± 5.8 to 152.5 ± 5.9 cm with obesity) (P < 0.001). Weight was greater (P < 0.001) in children with obesity at baseline as was the increase in weight after 1 yr (9.25 vs. 5.82 kg) (interaction, P = 0.005). Fat mass increased by 4.4 kg in children with obesity and by 1.1 kg in children without obesity (interaction, P < 0.001). However, there was no difference in fat-free mass between those with and without obesity at baseline (29.9 ± 5.9 vs. 31.6 ± 4.8 kg) (P = 0.206) with both groups increasing similarly over 1 year (gain of 4.87 vs. 4.85 kg with and without obesity, respectively). Without intervention, the increase in fat mass is four times greater in children with obesity after 1 year as compared with children without obesity.NEW & NOTEWORTHY Little is known about changes in body composition in children with and without obesity following 1 year of nonintervention. We report that without intervention, fat mass gain is significantly greater in children with obesity after 1 year compared with those without obesity. Body mass index (BMI) and %body fat measurements after 1 year yielded no significant increase suggesting that BMI and %fat alone are not suitable measures for tracking changes in adiposity among children.

Laboratory stewardship perceptions and testing patterns at a pediatric tertiary care center.

Despite stewardship efforts, laboratory testing overuse persists across medicine. To understand laboratory stewardship perceptions and testing patterns at a tertiary care pediatric hospital so that we could identify potential improvement opportunities. An electronic survey exploring laboratory stewardship was sent to all pediatric medicine resident and staff physicians. Laboratory testing data were also assessed for patterns of testing and overuse. The survey response rate was 54% (43/80). The results indicated good familiarity with stewardship but poor familiarity with testing specifics (eg, cost). A mobile reference application was the most preferred quality improvement intervention, and online modules were the least desired. Overuse was apparent, with as many as 53% of laboratory tests being repeated within 7 days and only half of repeated tests subsequently yielding abnormal results. Altogether, the data we collated demonstrated poor understanding of laboratory stewardship and substantial repeat testing with few abnormal results. These study findings suggest that laboratory stewardship is lacking at our center, and that multiple improvement opportunities exist.

Sensitivity Analysis of Performance Tests for Six-Degree-of-Freedom Serial Industrial Robots

Abstract The international standard ISO 9283:1998 is popular for performance tests of industrial robots at present. It is desirable that the tests described in this standard should be sensitive to error sources of robot end positioning/orientation. In this paper, first, the kinematic and the joint stiffness model parameters are identified experimentally for two models of six-DOF (degree-of-freedom) serial industrial robots (i.e., the ABB IRB 1410 and UR5 robots). Then, the standard deviations of the derived model parameters are obtained as error inputs for the sensitivity analysis of the performance tests including the positioning/orientation accuracy/repeatability tests. By simulating the error sensitivity of the positioning/orientation accuracy/repeatability test methods for industrial robots, it is analyzed whether the tests described in the ISO 9283:1998 Standard are sensitive to the focused error sources, showing the limitations of the evaluation index of the ISO 9283:1998 Standard. The results show that for six-DOF serial industrial robots, the positioning accuracy test is the key to determining their motion performance. The orientation accuracy and repeatability tests are not necessary if the positioning accuracy and repeatability tests can be done for six-DOF serial industrial robots. Finally, the improvement suggestion of the performance test method is proposed. The research of this paper is beneficial for improving the performance evaluation methods of industrial robots. It can also help robot manufacturing enterprises analyze and improve the positioning/orientation accuracy/repeatability of their products.

Advancements in integrated robotic sensing: A European perspective.

Robotic Non-destructive Testing and Sensing stands at the forefront of technological innovation, offering capabilities in assessing structural integrity, safety, and material quality across diverse industries. This comprehensive review article provides a detailed exploration of the field, focusing on the substantial contributions of European researchers and institutions. The need for non-destructive testing has been a constant in industries that rely on structural integrity, including aerospace, manufacturing, energy, construction, and healthcare. Traditional testing methods, such as radiography, ultrasonic testing, magnetic particle testing, and dye penetrant testing, have been integral for quality control and safety assurance. However, the robotisation of such methods has marked a profound shift, enabling precise, fast, efficient, and repeatable testing while minimising human exposure to hazardous environments. European researchers and institutions have played an instrumental role in driving the evolution of integrated robotic sensing. The historical perspective of the field reveals the pioneering spirit of Europe, as collaborative initiatives led to the development of robotic platforms equipped with advanced sensors and testing techniques. A critical aspect of the European impact on robotic inspection applications lies in developing advanced sensors, innovative robotic platforms, novel robotic path-planning and control approaches and data collection and visualisation tools. These developments continue to influence the global landscape of robotic sensing. European researchers remain at the forefront of current trends and innovations as the field continues to evolve. This review article will delve into these recent advancements, highlighting Europe's pivotal role in pushing the boundaries of technology and application. The implications and applications of robotic sensing reverberate across multiple sectors worldwide. From inspecting critical aerospace components to ensuring the quality of manufactured goods, these technologies underpin safety and quality standards.

Analytical Method Validation of Thorium in Ore Sample Using UV-Vis Spectrophotometer

Monazite contains several rare earth elements (REE) along with radioactive elements, i.e., thorium (Th) and uranium (U). Thorium content in monazite is several times higher than uranium. Monazite contains around 12% thorium oxide, but the thorium content in this mineral varies depending on location. To determine the thorium content in monazite, an appropriate and validated analytical method is needed so that the reliability of the test results can be trusted. Apart from that, method validation is one of the clauses in SNI ISO/IEC 17025:2017 that must be fulfilled by the laboratory to be certified and produce reliable data. This research aims to validate analytical methods for non-standard and modified methods that are likely to be used outside the scope. In this research, the method used to digest and analyze thorium in mineral samples refers to the ASTM E2941-14 method with several modifications. Therefore, the analysis method needs to be validated. Validation of the analytical method is carried out by testing several parameters such as linearity and working range tests, accuracy, precision (repeatability), Limit of Detection (LOD), and Limit of Quantitation (LOQ). The results of linearity, accuracy, and repeatability tests that meet the acceptance requirements can be used as a method of validation evaluation. The results of the method validation parameter test met the acceptance requirements, with the linearity test showing a coefficient of determination (R2) of 0.997, the accuracy test showing % a recovery value of 106.22%, and the precision (repeatability) test showing %RSD of 3.76% with LOD value is 0.650 mg/L, and LOQ is 0.724 mg/L. Based on the results of these parameter tests, the method for analyzing thorium in mineral samples was validated.

Preparation of Samples for the Study of Rheological Parameters of Digested Pulps in a Bioreactor of an Agricultural Biogas Plant

The studies of the rheology of digested pulp from agricultural biogas plants have often been fragmentary and non-standardised due to their complexity and time-consuming nature. As a result of measurements, it was possible to develop a procedure and range of measurements for the correct determination of the parameters of the carrier substance. The applicability of the coaxial cylinder measurement system was demonstrated for assessing the rheological parameters of digested pulp from a fermenter that utilises agricultural biomass. To determine the characteristics of solid particles, the Zingg diagram was used, inter alia, allowing the comparison of particles from each fraction. The analysis of the shape and size of solid particles may help to describe the onset of motion of this phase, flow type, or sedimentation type. The authors propose a completely new research approach to obtain an appropriate, repeatable test conditions of medium, which is the carrier liquid from the biogas plant reactor. The proposed methodology and the scenario of the entire study make it possible to achieve scalable and comparable test results in any laboratory. The proposed solution eliminates the influence of most external factors on the sample and rheological measurements, and the effectiveness of the presented procedure was confirmed in tests.

A67 REDUCING INAPPROPRIATE GAMMA-GLUTAMYL TRANSFERASE TESTING FOR INPATIENTS: A QUALITY IMPROVEMENT INITIATIVE IN LAB WASTE REDUCTION APPLYING THE MODEL FOR CONTINUOUS IMPROVEMENT

Abstract Background Review of the literature identifies a rising trend in laboratory testing, with over 30% of tests estimated to be inappropriately repeated. Laboratory overutilization increases healthcare costs, and can lead to overdiagnosis, overtreatment and negative health outcomes. Indications for repeat Gamma Glutamyl Transferase (GGT) testing in adults are limited, particularly repeat testing within the same admission. Aims Our aim was to reduce the inappropriate ordering of repeat GGT testing by 25% for all inpatients at the London Health Sciences Centre (LHSC) over a one-year study period. Methods An interprofessional team was created to help engage relevant stakeholders, collect baseline data and reassess the indications for GGT testing. A combination of root cause analysis tools, specifically the Ishikawa diagram and Pareto chart, were employed to identify potential factors contributing to the overutilization of GGT testing. After prioritizing potential solutions, intervention bundles were developed, and Plan-Do-Study-Act (PDSA) cycles were created to target correctable factors. In PDSA cycle #1, the process started by eliminating GGT as a laboratory testing option in the three most commonly used admission order care sets. Considering the hierarchy of intervention effectiveness, PDSA cycle #2 involved implementing a computerized Clinical Decision Support (CDS) system to restrict the reordering of GGT tests within 72 hours of the same admission. Results Baseline data showed that in 2022, a total of 62,542 GGT tests were ordered, with an average of approximately 5,200 GGT tests ordered per month. Of these, 16.4% were ordered through the top 3 most prevalent admission order care sets, and around 25% of all GGT tests were repeats within 72 hours of admission. Referring to Figure 1, PDSA cycle #1 yielded no significant reduction in GGT testing. PDSA cycle #2 successfully reduced the proportion of repeat GGT tests ordered by 12% within two months of implementation, leading to an estimated annualized cost savings of approximately $37,440. Conclusions Our results establish the effectiveness of CDS systems in reducing laboratory testing overutilization, suggesting their superiority to individual care set targeting interventions, and emphasize the potential for cost-effective CDS development in contemporary healthcare. Funding Agencies None

Multicenter evaluation of BioCode GPP for syndromic molecular detection of gastrointestinal pathogens from stool specimens.

This study highlights performance of a novel technology for timely and accurate detection and differentiation of 17 common bacterial, viral, and protozoan causes of gastroenteritis. Utilizing molecular tests such as the BioCode Gastrointestinal Pathogen Panel may improve the detection of gastrointestinal pathogens and provide actionable results, particularly for patient populations at most risk.

Norms, convergent validity, test–retest reliability, and practice effects for verbal fluency overall performance, clustering, and switching in Spanish-speaking children

Objective We conducted two empirical studies (in a cross-sectional and a longitudinal design) with the aim at establishing normative data (including norms for strategy use [i.e., clustering and switching strategies] and performance over time), and examining the convergent validity, the test–retest reliability (3–4 wks interval) and the changes in performance with practice (1 year interval) of the different verbal fluency (VF) quantitative and qualitative scores in Spanish-speaking children and adolescents. Method In S1 (n = 620 6- to 15-year-old Spanish-speaking children and adolescents), MANCOVA and Pearson’s correlations were employed. In S2 (n = 148 6- to 12-year-old Spanish-speaking children), intraclass correlation coefficient (ICC), paired t-tests, and Confirmatory Factor Analysis (CFA) were used. Results S1 results showed an age effect on all VF measures (quantitative and qualitative). The number of switches/clusters was more related to total word productivity and to executive functions (EF) than the mean cluster size. In S2, a significant increase in phonological VF performance was observed on number of switches and word productivity scores from baseline (Time 1) to repeat testing at Time 2. Practice effects were observed at Time 3 on all measures except for semantic and phonological mean cluster size. Test–retest reliability coefficients at Time 2 for number of clusters and switches, but not for mean cluster size, fell in the moderate range, ranging from ICCs .61 to ICCs .81. Test–retest reliability coefficients for total word productivity were higher (ICCs above .80) and stronger when testing as a unity with CFA methods (ϕ=.94, p < .001). Conclusions These data may be relevant for informing the neuropsychological assessment of spontaneous cognitive flexibility in children with typical development (TD) and those with developmental or acquired disorders.

Projected Colorectal Cancer Incidence and Mortality Based on Observed Adherence to Colonoscopy and Sequential Stool-Based Screening.

Modeling supporting recommendations for colonoscopy and stool-based colorectal cancer (CRC) screening tests assumes 100% sequential participant adherence. The impact of observed adherence on the long-term effectiveness of screening is unknown. We evaluated the effectiveness of a program of screening colonoscopy every 10 years vs annual high-sensitivity guaiac-based fecal occult blood testing (HSgFOBT) using observed sequential adherence data. The MIcrosimulation SCreening ANalysis (MISCAN) model used observed sequential screening adherence, HSgFOBT positivity, and diagnostic colonoscopy adherence in HSgFOBT-positive individuals from the National Colonoscopy Study (single-screening colonoscopy vs ≥4 HSgFOBT sequential rounds). We compared CRC incidence and mortality over 15 years with no screening or 10 yearly screening colonoscopy vs annual HSgFOBT with 100% and differential observed adherence from the trial. Without screening, simulated incidence and mortality over 15 years were 20.9 (95% probability interval 15.8-26.9) and 6.9 (5.0-9.2) per 1,000 participants, respectively. In the case of 100% adherence, only screening colonoscopy was predicted to result in lower incidence; however, both tests lowered simulated mortality to a similar level (2.1 [1.6-2.9] for screening colonoscopy and 2.5 [1.8-3.4] for HSgFOBT). Observed adherence for screening colonoscopy (83.6%) was higher than observed sequential HSgFOBT adherence (73.1% first round; 49.1% by round 4), resulting in lower simulated incidence and mortality for screening colonoscopy (14.4 [10.8-18.5] and 2.9 [2.1-3.9], respectively) than HSgFOBT (20.8 [15.8-28.1] and 3.9 [2.9-5.4], respectively), despite a 91% adherence to diagnostic colonoscopy with FOBT positivity. The relative risk of CRC mortality for screening colonoscopy vs HSgFOBT was 0.75 (95% probability interval 0.68-0.80). Findings were similar in sensitivity analyses with alternative assumptions for repeat colonoscopy, test performance, risk, age, and projection horizon. Where sequential adherence to stool-based screening is suboptimal and colonoscopy is accessible and acceptable-as observed in the national colonoscopy study, microsimulation, comparative effectiveness, screening recommendations.

Prevention of Blowout Tests in Large-Diameter Boreholes with Soundless Chemical Demolition Agents and Fracturing Characteristics of Hard Sandstones

Increasing the diameter of the drillhole can facilitate drillhole breakage using soundless chemical demolition agents, but it is prone to cause drillhole blowout, resulting in crushing failure. This paper conducted a blowhole prevention test on a large borehole using the internal insertion cooling pipe method (ICBPM) to test the expansion pressure of cooling pipes with different diameters. During this test, a fracture occurred in a hole with a 75 mm inner diameter in the rectangular sandstone specimens with high strength. It was found that utilizing the ICBPM can effectively hinder the development of blowholes. Expansion and blowhole prevention are optimized with a 0.14 mass ratio of the cooling water to demolition agent and a maximum expansion stress of 49.0 MPa. The guiding effect of the minimum resistance line is significant. In repeated tests, all fissures are distributed in a Y-shape on the free surface where the minimum resistance line is located. The acoustic emission signals from statically fractured hard rock increase abruptly before damage, and the development of rock expansion and fracturing can be obtained through strain monitoring. These results suggest that the ICBPM can reduce the expansion time with a strong crushing effect, satisfying the need to process more crushing projects.

Channelized hotelling observer-based low-contrast detectability on the ACR CT accreditation phantom: Part II. Repeatability study.

Objective and quantitative evaluation for low-contrast detectability that correlates with human observer performance is lacking for routine CT quality control testing. Channelized Hotelling observer (CHO) is considered a strong candidate to fill the need but has long been deemed impractical to implement due to its requirement of a large number of repeated scans in order to provide accurate and precise estimates of index of detectability (d'). In our previous work, we optimized a CHO model observer on the American College of Radiology (ACR) CT accreditation phantom and achieved accurate measurement of d' with only 1-3 repeat scans. In this work, we aim to validate the repeatability of the proposed CHO-based low-contrast evaluation on four scanner models using the ACR CT accreditation phantom. The repeatability test was performed on four different scanners from two major CT manufacturers: Siemens Force and Alpha; Canon Prism and Prime SP. An ACR CT phantom was scanned 10 times, each time after repositioning of the phantom. For each repositioning, 3 repeated scans were acquired at 24, 12, and 6 mGy on all four scanner models. CHO was applied at the measured dose levels for different low-contrast object sizes (4-6mm). The CHO was also applied to images created using deep learning-based reconstructions on Canon Prism and to four different scan/reconstruction modes on the Siemens Alpha, a photon-counting-detector (PCD)-CT. The repeatability was evaluated by the probability that a measurement would fall within the±15% tolerance (P<15% ). With the CHO setting optimized for the ACR phantom and the use of 3 repeated scans and 9 non-overlapping slices per scan, the CHO measurement could provide high repeatability with P<15% of 98.8%-99.9% at 12 mGy with IR reconstruction on all four scanners. On scanner A, P<15% were 91.5%-99.9% at the three dose levels and for all three object sizes while the numbers were 93.6%-99.998% on scanner B. P<15% were 96.5%-97.2% for the two deep learning reconstructions and 97.0%-99.97% for the four scan/reconstruction modes on the PCD-CT. The CHO provided highly repeatable measurements with over 95% probability that a CHO measurement would lie within the±15% tolerance for most of the dose levels and object sizes on the ACR phantom. The repeatability was maintained when the CHO was applied to images created with a commercial deep learning-based reconstruction and various scan/reconstruction modes on a PCD-CT. This study demonstrates that practical implementation of CHO for routine quality control and performance evaluation is feasible.

Using Repeated Light-Weight Deflectometer Test Data to Predict Flexible Pavement Responses Based on the Mechanistic–Empirical Design Method

This study investigated the potential of lightweight deflectometer (LWD) data in predicting layer moduli and response measurements within the Mechanistic–Empirical Pavement Design Guide. To achieve this goal, field repeated LWD tests and laboratory repeated load triaxial tests were carried out on granular base material compacted at 3% and 6% water content, sandy subgrade soil compacted at 3%, 4% and 9% water content and silty sand subgrade soil compacted at 8% and 10% water content. The results revealed that substituting traditional repeated load triaxial (RLT) data with LWD data for predicting these parameters was notably effective for cohesionless materials, especially for unbound granular materials (UGMs) compacted at optimum water content. The accuracy and reliability of predictions were remarkably high, showcasing the potential of LWD to enhance efficiency and precision in pavement design within this context. Conversely, for cohesive road materials, the study emphasized the importance of considering specific material properties and water content when integrating LWD into the Mechanistic–Empirical Pavement Design Guide. The distinctive characteristics and behaviors of cohesive materials necessitate a nuanced approach. This understanding is critical to ensuring the accuracy and reliability of pavement design and assessment across diverse conditions. In summary, the study presents a promising avenue for utilizing LWD data in cohesionless road materials, offering potential cost and time-saving advantages. Additionally, it underscores the necessity of tailored approaches when considering material properties and moisture content for cohesive materials, thereby advancing the field of pavement engineering by providing insights for improved practices and adaptable frameworks.