Laboratory-based Tests Research Articles

Laboratory Assessment of Manual Wheelchair Propulsion

Self-propelled manual wheelchairs offer several advantages over electric wheelchairs, including promoting physical activity and requiring less maintenance due to their simple design. While theoretical analyses provide valuable insights, laboratory testing remains the most reliable method for evaluating and improving the efficiency of manual wheelchair drives. This article reviews and analyzes the laboratory methods for assessing the efficiency of wheelchair propulsion documented in the scientific literature: (1) A wheelchair dynamometer that replicates real-world driving scenarios, quantifies the wheelchair’s motion characteristics, and evaluates the physical exertion required for propulsion. (2) Simultaneous measurements of body position, motion, and upper limb EMG data to analyze biomechanics. (3) A method for determining the wheelchair’s trajectory based on data from the dynamometer. (4) Measurements of the dynamic center of mass (COM) of the human–wheelchair system to assess stability and efficiency; and (5) data analysis techniques for parameterizing large datasets and determining the COM. The key takeaways include the following: (1) manual wheelchairs offer benefits over electric ones but require customization to suit individual user biomechanics; (2) the necessity of laboratory-based ergometer testing for optimizing propulsion efficiency and safety; (3) the feasibility of replicating real-world driving scenarios in laboratory settings; and (4) the importance of efficient data analysis techniques for interpreting biomechanical studies.

No differences between remote and laboratory-based testing of cardiac interoceptive accuracy using the phase adjustment task

In recent years, there has been an increased interest in remote testing methods for quantifying individual differences in interoception, the perception of the body’s internal state. Hampering the adoption of remote methods are concerns as to the quality of data obtained remotely. Using data from several studies, we sought to compare the performance of individuals who completed the Phase Adjustment Task—a new measure of cardiac interoceptive accuracy that can be administered via a smartphone application—supervised in a laboratory against those who completed the task remotely. Across a total sample of 205 individuals (119 remote and 86 laboratory), we observed no significant differences in task performance between the two groups. These results held when matching groups on demographic variables (e.g., age) and considering only individuals who had successfully completed a screener task. Overall, these data attest to the suitability of the Phase Adjustment Task for remote testing, providing an opportunity to collect larger and more diverse samples for future interoception research.

Real-world use of multiplex point-of-care molecular testing or laboratory-based molecular testing for influenza-like illness in a 2021 to 2022 US outpatient sample.

While molecular testing is recommended for symptomatic patients suspected of having coronavirus disease 2019 (COVID-19), limited data are available examining real-world use of tests for severe acute respiratory syndrome coronavirus (SARS-CoV-2) and the impact of SARS-CoV-2 testing on patient outcomes. In this retrospective cohort study using de-identified administrative claims data in the Optum Labs Data Warehouse, we identified 2 groups of patients with ≥1 outpatient claims with a procedure code for SARS-CoV-2 testing between January 2021 and September 2022. Group 1 had ≥1 claims with CPT code 0240U or 0241U ("Xpert Xpress") (N = 51,602); Group 2 had ≥1 claims for laboratory-based molecular testing (N = 317,192). Outcomes assessed on the identification date and through the 90-day follow-up included claims evidence of use of SARS-CoV-2, influenza, and respiratory syncytial virus (RSV) tests, diagnosis of active COVID-19, influenza, or RSV, and use of treatments (antivirals for COVID-19, influenza, and RSV and other treatments for COVID-19 and RSV). Patients in Group 1 had fewer tests for SARS-CoV-2, influenza, or RSV (mean ± standard deviation 1.6±1.4 versus 2.6±2.6, standardized difference -0.45), faster time to diagnosis of COVID-19 (median 0 versus 4 days, standardized difference -0.27) or influenza (median 0 versus 5 days, standardized difference -0.74), and faster time to treatment of COVID-19, influenza, or RSV (median 1 versus 5 days, standardized difference 0.16) than patients in Group 2. In this nationwide real-world study of outpatient testing, use of point-of-care molecular multiplex SARS-CoV-2 testing resulted in fewer claims for SARS-CoV-2, influenza, and RSV tests, faster time to diagnosis, and faster time to treatment than laboratory-based molecular testing.

Agreement Between a Portable Cholesterol Device and Laboratory-Based Testing in Older Adults

Agreement Between a Portable Cholesterol Device and Laboratory-Based Testing in Older Adults

Behaviour of paddled energy-absorbing rockbolts under complex loading laboratory conditions

Since their introduction in 2010, paddled energy-absorbing rockbolts have been widely used in seismically active hard rock mines. This paper provides new data and reviews previous work to quantify the performance of paddled energy-absorbing rockbolts under controlled laboratory conditions. Of significance is the realization that the typical split location in impact tests, at the centre between two paddle anchor points can at best provide an upper limit value. This inherent variability in performance under different testing configurations should be acknowledged and taken into consideration in the design of ground support in seismic conditions. This paper discusses the reduction in capacity of paddled rockbolts as a function of loading angle from a maximum value during axial tests (0° loading angle) to the lowest value during pure shear (loading angle of 90°). A significant reduction in displacement capacity is observed as the loading angle changes between axial (0°) and 40°. Beyond a 40° loading angle up to shear (90°) loading the reduction in displacement capacity is less significant. Due to the variances in the capacity observed through the variance of the testing configuration: loading mechanism, direction of loading, location / presence of a discontinuity, it must be recognized that results from laboratory-based testing are not independent of the testing configuration. This should be acknowledged when extrapolating anticipated performance in the field.

Accuracy of point-of-care SARS-CoV-2 detection using buccal swabs in pediatric emergency departments.

To optimize the identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children, specimen collection and testing method are crucial considerations. Ideally, specimen collection is easy and causes minimal discomfort, and the laboratory approach is simple, accurate, and rapid. In this prospective cohort study we evaluated the accuracy of a point-of care nucleic acid device using caregiver/patient self-collected buccal swabs. Participants were recruited in 14 Canadian tertiary care pediatric emergency departments. Children <18 years of age deemed to require SARS-CoV-2 testing were eligible. Caregivers or the patient-collected buccal swabs which were tested on the ABBOTT ID NOW. The reference standard was nasopharyngeal swab specimens collected by a healthcare provider tested via laboratory reverse transcription PCR (RT-PCR). We enrolled 2,640 study participants and 14.4% (381/2,640) were SARS-CoV-2 RT-PCR-positive. Eight percent (223/2,640) and 85.0% (2,244/2,640) were concordant test-positive and concordant test-negative, respectively. Sensitivity and specificity of the investigational approach were 58.5% [95% confidence interval (CI): 53.4, 63.5] and 99.3% (95% CI: 98.9, 99.6), respectively. Cycle threshold values were lower among concordant [median 17 (15, 21)] relative to discordant [median 30 (22, 35)] swabs (P < 0.001). Sensitivity was greatest among children <4 years of age, when caregivers performed the swabs, among unvaccinated children, and those with shorter symptom duration. Across multiple pain measures, less pain was associated with buccal swab testing. Although accuracy of the buccal swab point-of-care SARS-CoV-2 test was good and negative agreement was excellent, sensitivity was only 58.5%. Concordance was greater among those with higher viral loads, and the approach involving buccal swabs was less painful.IMPORTANCETo optimize the identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children, specimen collection and testing method are crucial considerations. Ideally, specimen collection is easy and causes minimal discomfort, and laboratory approach is simple, accurate, and rapid. We evaluated the accuracy and pain associated with buccal swab specimen collection by caregivers or children themselves who were tested using a point-of-care isothermal nucleic acid amplification SARS-CoV-2 test. This novel approach was compared to nasopharyngeal swab specimens tested using laboratory-based PCR tests. While negative agreement was excellent, positive percent agreement was less than 60%. Concordance was greater among those with higher viral loads, and thus, sensitivity is excellent when transmissibility is more likely to occur. Importantly, the approach involving buccal swabs was significantly less painful, and thus, children and their caregivers are more likely to agree to testing using such an approach.CLINICAL TRIALSRegistered at ClinicalTrials.gov (NCT05040763).

Transferability of Model-Based Static Coefficient of Friction

The accurate determination of static coefficients of friction (COFs) is crucial in engineering design, yet standard reference values often show considerable variability. As a result, engineers frequently need to perform experimental COF measurements to ensure the reliable transferability of model-based COFs to real-world components. However, the effectiveness of cost-efficient laboratory tests, typically conducted on standardized samples, in reflecting actual component performance is often questioned as it is not trivial to transfer and scale the tribosystem. This study addresses this issue by conducting friction coefficient experiments on interference fits and flange connections, comparing the results with laboratory-based COF tests. The findings reveal a strong correlation when the tribological conditions of the real assembly are replicated in the lab. This research offers a method to enhance the accuracy and transferability of COF values from lab tests to practical applications, providing engineers with a more reliable approach to friction testing.

Deep Learning-Enhanced Paper-Based Vertical Flow Assay for High-Sensitivity Troponin Detection Using Nanoparticle Amplification.

Successful integration of point-of-care testing (POCT) into clinical settings requires improved assay sensitivity and precision to match laboratory standards. Here, we show how innovations in amplified biosensing, imaging, and data processing, coupled with deep learning, can help improve POCT. To demonstrate the performance of our approach, we present a rapid and cost-effective paper-based high-sensitivity vertical flow assay (hs-VFA) for quantitative measurement of cardiac troponin I (cTnI), a biomarker widely used for measuring acute cardiac damage and assessing cardiovascular risk. The hs-VFA includes a colorimetric paper-based sensor, a portable reader with time-lapse imaging, and computational algorithms for digital assay validation and outlier detection. Operating at the level of a rapid at-home test, the hs-VFA enabled the accurate quantification of cTnI using 50 μL of serum within 15 min per test and achieved a detection limit of 0.2 pg/mL, enabled by gold ion amplification chemistry and time-lapse imaging. It also achieved high precision with a coefficient of variation of <7% and a very large dynamic range, covering cTnI concentrations over 6 orders of magnitude, up to 100 ng/mL, satisfying clinical requirements. In blinded testing, this computational hs-VFA platform accurately quantified cTnI levels in patient samples and showed a strong correlation with the ground truth values obtained by a benchtop clinical analyzer. This nanoparticle amplification-based computational hs-VFA platform can democratize access to high-sensitivity point-of-care diagnostics and provide a cost-effective alternative to laboratory-based biomarker testing.

Autonomic Reactivity to Mental Stress is Associated with Cardiovascular Mortality

Abstract Background and Aims The mechanisms linking acute psychological stress to cardiovascular disease (CVD) mortality are incompletely understood. We studied the relationship of electrocardiographic measures of autonomic dysfunction during acute mental stress provocation and CVD death. Methods In a pooled cohort of 765 participants with stable CVD from two related studies, we collected Holter data during standardized laboratory-based mental stress testing with a speech task and followed them for events. We assessed autonomic function using low frequency (LF) heart rate variability (HRV) in five-minute intervals before, during, and after stress induction, and specifically examined changes from rest to stress. We employed cause-specific survival models to examine its association with CVD and all-cause mortality, controlling for demographic and CVD risk factors. Results The mean (SD) age was 58 (10) years, 35% were women, and 44% self-identified as Black. After a median follow-up of 5.6 years, 37 (5%) died from CVD causes. A stress-induced low frequency (LF) HRV decrease (67% of sample), versus increase, was associated with a hazard ratio (HR) of 3.48 (95% confidence interval, 3.25, 3.73) for CVD mortality. Low rest LF HRV (bottom quartile) was also independently associated with CVD mortality, HR = 1.75 (1.58, 1.94), versus normal rest LF HRV (upper three quartiles). The combination of stress-induced LF HRV decrease and low rest LF HRV was associated with HR = 5.73 (5.33, 6.15) versus the normal stress/rest LF HRV reference. We found similar results with HF HRV. Conclusions Stress-induced LF HRV decrease and low rest LF HRV are both independently and additively associated with a higher CVD mortality risk. Additional research is needed to assess whether targeting autonomic dysfunction may improve CVD outcomes.

Evaluation of Hepatitis C Virus Transmission Through Endoscopy Procedures in the Country of Georgia.

Exposure to healthcare procedures might be a source of hepatitis C virus (HCV) transmission in Georgia, one of the few countries currently on track to eliminate hepatitis C. While there has been a history of iatrogenic transmission of HCV, the risk of HCV transmission related to endoscopic procedures has not been previously assessed in Georgia. The goal of this study was to assess HCV seroconversion among individuals undergoing endoscopic procedures to estimate the relative role and incidence of HCV infection attributable to endoscopic procedures. A prospective cohort study was conducted in four endoscopy units in two cities (Tbilisi and Kutaisi) of Georgia during April-September, 2021. Recruitment of study participants was conducted using convenience sampling, and every eligible patient was approached and invited to participate in the study. Study population included adults (age ≥ 18 years) who received an endoscopic procedure (gastroscopy, colonoscopy and bronchoscopy) in inpatient or outpatient unit at the study sites. HCV antibody (anti-HCV) testing was conducted using rapid diagnostic test (RDT) on the same day they underwent the endoscopic procedure. Patients with a non-reactive anti-HCV baseline test were retested after 6 months. Patients with reactive baseline tests were excluded from the study and linked to further testing and care. Participants with a reactive result on follow-up RDTs were retested using a lab-based anti-HCV and HCV ribonucleic acid (RNA) test. A total of 981 HCV antibody non-reactive participants were enrolled; 590 (64.8%) of them were reached and retested after 6 months. At retesting, two out of 590 (0.3%) individuals had a reactive anti-HCV result on RDT and both were negative on laboratory-based anti-HCV and HCV RNA tests. Based on the results of this study, endoscopic procedures were not shown to contribute to HCV transmission in Georgia.

Laboratory-based molecular test alternatives to RT-PCR for the diagnosis of SARS-CoV-2 infection.

Laboratory-based molecular test alternatives to RT-PCR for the diagnosis of SARS-CoV-2 infection.

Multiple Organ Dysfunction Syndrome in Malawian Children with Cerebral Malaria.

More than 1,000 children under 5 years of age die every day from malaria. Cerebral malaria (CM) is the most severe and deadly manifestation of the disease. The occurrence of multiple organ dysfunction syndrome (MODS) has been associated with increased mortality in adult patients with CM. However, little is known about the frequency and severity of MODS in children with CM. This was a retrospective study of 199 pediatric patients with CM admitted to a referral hospital in Blantyre, Malawi, between January 2019 and May 2023. Data were abstracted from charts to calculate scores using four established scoring systems: Pediatric Logistic Organ Dysfunction-2 (PELOD-2), Pediatric Sequential Organ Failure Assessment (pSOFA), Signs of Inflammation in Children that Can Kill (SICK), and Lambaréné Organ Dysfunction Score (LODS). Mortality was 16% (n = 32). All four scoring systems were predictive of mortality, but the PELOD-2 and pSOFA scores outperformed the others with area under the curve values of 0.75 and 0.67, respectively. Multiple organ dysfunction syndrome was diagnosed in 182 patients (91%) using the PELOD-2 score, 172 patients (86%) using the pSOFA score, 99 patients (50%) using the SICK score, and 30 patients (15%) using the LODS. The PELOD-2 and pSOFA identify MODS in children with CM but require laboratory-based testing that is often unavailable in malaria-endemic areas. Furthermore, these scoring systems may identify primary malarial disease pathology rather than true organ dysfunction. Simplified scoring systems designed to recognize and quantify MODS in this patient population may provide opportunities for improved resource allocation and timely, organ-specific treatment.

A novel approach to assess internal pore structure and quantify tortuosity of clogged pervious concrete through image analysis techniques

ABSTRACT The major objective of this research was to develop an innovative approach to characterise the pore structure of pervious concrete (PC) mixtures and quantify tortuosity in pre- and post-clogged conditions through 2D and 3D image analysis. Four different types of PC mixtures were prepared and subjected to computed tomography (CT) scanning to retrieve morphological information covering over 1900 images, followed by tortuosity quantification of each of 200 interconnected pore paths using vascular modelling toolkit (VMTK). The porosity of PC obtained from laboratory-based tests was 10–25% lower than image analyses. Further, along the depth of PC, a significant decrease in the number of pores in the top 60–80 mm was observed due to clogging, which revealed that maintenance be adopted only in the top 80 mm. Control and clogged PC with smaller sized aggregates and lower w/c ratio were more tortuous compared to higher w/c ratio while opposite for larger sized aggregates, ascribed to the occurrence of shorter interconnected pore paths comprising larger pore diameter, remarking that permeability will depend on both tortuosity and path diameter. CT scanning was used in predicting tortuosity and pore interconnectivity of PC through VMTK approach extensively used in medical science and seldom used in engineering.

The effects of HIV self-testing on HIV incidence and awareness of status among men who have sex with men in the United States: Insights from a novel compartmental model

BackgroundThe OraQuick In-Home HIV self-test represents a fast, inexpensive, and convenient method for users to assess their HIV status. If integrated thoughtfully into existing testing practices, accompanied by efficient pathways to formal diagnosis, self-testing could enhance both HIV awareness and reduce HIV incidence. However, currently available self-tests are less sensitive, particularly for recent infection, when compared to gold-standard laboratory tests. It is important to understand the impact if some portion of standard testing is replaced by self-tests. We used a compartmental model to evaluate the effects of self-testing in diverse scenarios among gay, bisexual and other men who have sex with men (MSM) in the United States for the period 2020–2030, and to understand which scenarios maximize the advantages of self-testing. MethodsWe introduced a novel 4-compartment model for HIV self-testing. We employed the model under different screening rates, self-test proportions, and delays to diagnosis for those identified through self-tests to determine the potential effects of self-testing on HIV incidence and awareness of status when applied to the US MSM population. We studied scenarios in which self-tests supplement laboratory-based tests, with no replacement, and scenarios in which some replacement occurs. We also examined how future improvements in self-test sensitivity may affect our results. ResultsWhen HIV self-tests are supplemental rather than substitutes for laboratory-based testing, self-testing can decrease HIV incidence among MSM in the US by up to 10 % and increase awareness of status among MSM from 85 % to 91 % over a 10-year period, provided linkage to care and formal diagnosis occur promptly following a positive self-test (90 days or less). As self-tests replace a higher percentage laboratory-based testing algorithms, increases in overall testing rates were necessary to ensure reductions in HIV incidence. However, such needed increases were relatively small (under 10 % for prompt engagement in care and moderate levels of replacement). Improvements in self-test sensitivity and/or decreases in the detection period may further reduce any necessary increases in overall testing by up to 40 %. ConclusionsIf properly utilized, self-testing can provide significant long-term reductions to HIV incidence and improve awareness of HIV status. Ensuring that self-testing increases overall testing and that formal diagnosis and engagement in care occur promptly following a positive self-test are necessary to maximize the benefits of self-testing. Future improvements in self-test sensitivity and reductions in the detection period would further reduce HIV incidence and the potential risks associated with replacing laboratory tests with self-tests.

A-236 Rapid multiplexed PCR (polymerase chain reaction) tests for respiratory disease improve process and time to diagnosis versus laboratory-based molecular testing

Abstract Background The Infectious Disease Society of America recommends molecular testing for symptomatic patients suspected of having COVID-19. Molecular tests can be performed at the point of care or in a centralized laboratory, using different methodologies, and can be singleplex or multiplex. Limited data are available examining the use of these tests in clinical practice and impact of different test types on patient outcomes; however, common antiviral treatments for both COVID-19 and influenza are more effective when taken earlier and are not indicated for use more than 5 and 2 days after symptom onset, respectively. The aim of this study was to describe the diagnostic journey for non-inpatients who received molecular testing for respiratory pathogens in the laboratory versus those who received testing using a rapid, multiplexed real-time RT-PCR test that can be performed at the point of care. Methods De-identified administrative claims were analyzed from July 1, 2020 through September 30, 2022 for commercially insured and Medicare Advantage enrollees in the Optum Labs Data Warehouse. Patients with ≥1 medical claim for a non-inpatient visit with a procedure code for testing for SARS-CoV-2 were identified; patients who received antigen testing at index were excluded. Patients were followed for up to 90 days. Two patient groups were selected for the final study sample: 1) Patients with ≥1 claim with CPT code 0240U or 0241U with a point-of-care or laboratory place of service on the index date (proprietary laboratory analyses codes for Xpert® Xpress CoV-2/Flu/RSV, or “Xpert Xpress”); and 2) Patients with other laboratory-based molecular testing on the index date. Standardized difference of &amp;gt;0.10 or &amp;lt;-0.10 was considered a significant imbalance in proportions or means. Results In total, 51,602 patients received testing with Xpert Xpress while 317,192 received laboratory testing. Patients who were tested with Xpert Xpress were significantly older (mean 49.82 vs 42.19, SD 0.3), had a higher Charlson Comorbidity Index (mean 0.7 vs 0.35, SD 0.29), and were more likely to have a respiratory risk factor (6.09% vs 2.38%, SD 0.19). On average, patients who were tested with Xpert Xpress had significantly fewer tests for SARS-CoV-2 on the index date (mean 1.2 vs 1.58, SD -0.55), and fewer tests for SARS-CoV-2, influenza, or RSV on the index date and through the end of the 90-day fixed follow-up period (mean 1.64 vs 2.57, SD -0.45). They were also significantly more likely to be diagnosed with COVID-19 on the index date (23.31% vs 16.53%, SD 0.17). Among patients with a diagnosis for COVID-19, mean time to diagnosis was significantly shorter among patients tested with Xpert Xpress (4.85 vs 8.86 days, SD -0.27; median 0 vs 4 days). This finding was also consistent for influenza (4.05 vs 20.28 days, SD -0.74; median 0 vs 5 days). Conclusions Testing with Xpert Xpress at index resulted in fewer total tests and faster diagnosis compared to testing in the laboratory. Rapid, multiplex PCR testing provides a faster time to diagnosis and may support more appropriate and effective treatment.

A-213 Comparison of low-density lipoprotein cholesterol (LDL-c) estimates by in-lab and point-of-care devices in the context of emerging LDL-c equations

Abstract Background Low-density lipoprotein cholesterol (LDL-c) and lipid measurements are used for hyperlipidemia diagnosis, cardiovascular disease risk classification, and medication management. Millions of lipid panels are performed annually. Given the widespread need for lipid testing, there are two CLIA-waived point-of-care (POC) lipid testing devices. These devices were FDA-approved using the Friedewald equation to estimate LDL-c based on measurements of (triglycerides (TG), high-density lipoprotein cholesterol (HDL-c), and total cholesterol (TC). However, in laboratory-based testing, the Friedewald equation is being replaced by newer, more accurate equations such as the NIH-Sampson equation. These equations use the same lipid panel results to estimate LDL-c and only differ in the arithmetic of the estimation. The study objective is to evaluate how differences between the in-clinic POC machines and in-laboratory lipid measurements affect the estimated LDL-c results and are compounded by differences in the equations used for LDL-c estimation. Methods This retrospective observational study collected deidentified lipid results (TG, HDL-c, TC, LDL-c) and demographic data (age, gender) for all samples that had lipid panel results from in-lab and POC within twenty-four hours of each other in a single hospital system between 2014 and 2023. Three hundred twenty samples were identified; samples with non-numerical values or results outside of the reportable range for TG, HDL-c, or TC were not included in subsequent LDL-c calculations using the Friedewald and NIH-Sampson equations (69 results). Patients under the age of 18 were excluded (2 results). Two hundred and forty-nine samples met inclusion criteria; this cohort showed non-significant differences in lipid, age, and gender distributions relative to all POC results tested in the same time frame. Results Consistent with prior reports, we observed discordance between POC and the in-lab lipid measurements, particularly for TG (Bland-Altman: bias:-23.04 mg/dL, standard deviation:61.3 mg/dL). Regardless of the testing platform, LDL-c results are higher on an individual and population-based level with the NIH-Sampson equation. These analytical differences may not change clinical management if the cardiovascular risk classification using estimated LDL-c is unchanged. However, the risk classification based on the in-lab versus in-clinic testing differed for 20-30% of patients. The most pronounced difference in LDL-c estimation occurred when the POC machine used Friedewald and in-lab testing used NIH-Sampson, and resulted in 5% more patients differentially classified. Conclusions This study highlights the need for transparency in lipid panel reports regarding which LDL-c equation is used in both POC and in-lab testing formats, and the need for readily available tools for conversion between different LDL-c estimation equations.

B-192 Covid on the PCR Pro: a consumer-friendly PCR test

Abstract Background The emergence of COVID-19 highlighted the need for rapid and accurate diagnostic solutions that can be deployed on a broad scale. The complexity and long turn-around-time of PCR testing typically performed in molecular laboratories is not compatible with community-wide screening. To overcome these challenges, we present the Co-Dx PCR Pro™, a rapid and simple test platform developed for self-collection and at-home use. The instrument is controlled from the user’s smartphone or tablet and performs sample treatment, RT-PCR, and DNA melting analysis. An automatic calling algorithm provides a simple, “Detected,” or, “Not detected,” result. We demonstrate the utility of this platform using a test for the detection of SARS-COV-2. Methods A self-collected anterior nasal swab sample and 2 mLs of water are added to the collection cup. Closing the lid of the cup initiates rehydrating a dried Proteinase K mixture to digest proteins in the sample. After a brief Proteinase K heat-kill step, the instrument mixes the sample with a dried PCR master mix. Primers target two SARS-COV-2 specific genes (RdRp and E gene) and the human RNase P gene as a control. The sample undergoes an RT step followed by 45 cycles of PCR and DNA melting analysis. Detection is by an automatic calling algorithm that identifies a SARS-COV-2 amplicon melting peak at 82°C and RNase P peak at 87°C. The total runtime is less than 30 minutes. The limit of detection for the assay was assessed by contriving intact virus in negative sample matrix, which was then applied to dry swabs. In addition, frozen and banked clinical samples were tested using the Logix Smart®™ Covid-19 test as a comparator assay. A third party performed a usability assessment by having (1) naïve users follow the instructions and self-administer the test (2) expert trained users perform an independent assessment of the assay. Participants were then asked to complete a usability assessment. Results The 95% limit of detection was 2,100 copies/swab using contrived nasal swabs. Clinical samples were blinded to the operator and run on the platform. All samples resulted in a diagnosis concordant with the comparator assay. The usability assessment was performed by six naïve users and resulted in a systems usability scale score of “Best” (84.2 ± 14.3, out of 100). The two expert users determined an 80% limit of detection of 700 genome equivalents and “ease of use,” and “satisfaction,” scores of 4.5/5.0 and 5.0/5.0, respectively. Conclusions Performance of the PCR Pro platform is on par with laboratory-based PCR testing. The benefits of our assay are its speed and the low complexity platform accessible to the lay. This platform could improve access to molecular diagnostic testing, including use at home. Future expansion to include common respiratory pathogens (Flu, RSV, Strep) will increase utility. Additionally, anonymized results can be aggregated and provide a wealth of epidemiological information at the community level to better inform public health initiatives and health outcomes.

Bearing performance and failure mechanisms of HSCM piles in marine soft soil under lateral loads

Helix Stiffened Cement Mixing (HSCM) pile represents a novel type of grouted composite pile known for its excellent compressive and tensile performance. Based on field tests, this study introduces a laboratory-based test design methodology and piling technique for HSCM piles. A comprehensive analysis of their horizontal bearing capacity, pile-soil failure mode, optimal piling technique, and reinforcement mechanism is performed. SEM-EDS technology is utilized at a microscopic scale to examine the reinforcement mechanism of HSCM piles. Through ABAQUS finite element simulation, a full-scale model simulating the HSCM pile-soil interaction is developed. The analysis includes pile cross-sectional stress, displacement, and pile-soil failure mode. The p−y curve of the HSCM pile is then plotted, elucidating the reinforcement mechanism of cemented soil. The results indicate that compared to ordinary helical piles, the horizontal bearing capacity of HSCM piles increases by 125.9%. SEM-EDS images reveal that cement and kaolin form a mutual bond, enhancing the strength of the soil around the pile. Additionally, unlike other composite piles, the direction of soil flow around HSCM piles encircles the first helix of the pile core. This research offers a design basis for understanding the horizontal bearing performance and failure mechanisms of HSCM piles in marine soft soil.

CMFHMDA: a prediction framework for human disease-microbe associations based on cross-domain matrix factorization.

Predicting associations between microbes and diseases opens up new avenues for developing diagnostic, preventive, and therapeutic strategies. Given that laboratory-based biological tests to verify these associations are often time-consuming and expensive, there is a critical need for innovative computational frameworks to predict new microbe-disease associations. In this work, we introduce a novel prediction algorithm called Predicting Human Disease-Microbe Associations using Cross-Domain Matrix Factorization (CMFHMDA). Initially, we calculate the composite similarity of diseases and the Gaussian interaction profile similarity of microbes. We then apply the Weighted K Nearest Known Neighbors (WKNKN) algorithm to refine the microbe-disease association matrix. Our CMFHMDA model is subsequently developed by integrating the network data of both microbes and diseases to predict potential associations. The key innovations of this method include using the WKNKN algorithm to preprocess missing values in the association matrix and incorporating cross-domain information from microbes and diseases into the CMFHMDA model. To validate CMFHMDA, we employed three different cross-validation techniques to evaluate the model's accuracy. The results indicate that the CMFHMDA model achieved Area Under the Receiver Operating Characteristic Curve scores of 0.9172, 0.8551, and 0.9351$\pm $0.0052 in global Leave-One-Out Cross-Validation (LOOCV), local LOOCV, and five-fold CV, respectively. Furthermore, many predicted associations have been confirmed by published experimental studies, establishing CMFHMDA as an effective tool for predicting potential disease-associated microbes.

Garmin Fénix 7® underestimates performance at the lactate threshold in comparison to standardized blood lactate field test

Introduction &amp; Purpose Lactate threshold (LT) is a critical performance measure traditionally obtained using costly laboratory-based tests. Wearables offer a practical and noninvasive alternative for LT assessment in recreational and professional athletes. However, the comparability of these estimates with the gold standards requires further evaluation. This study therefore aimed to compare pace and heart rate (HR) at the LT between the Garmin Fenix 7® threshold running test and a standardized blood lactate field test. Methods In our sample of 26 participants (nf = 7 and nm = 19; 25.97 (± 6.26) years, BMI: 24.58 (± 2.8) kg/m2) we determined running pace and HR at LT with two subsequent tests. First, all participants were equipped with a Fenix 7® smartwatch for a calibration phase of 5 weeks. Subsequently, all performed the Fenix 7® threshold running test, which guides the athlete through incrementing HR zones. Based on that, the watch estimated pace and HR at LT. After a break of at least 48 h, they were tested in a standardized, graded blood lactate field test analyzed by the modified D-Max method (Cheng et al, 1992). Results Pace at LT calculated by Fenix 7® (M =11.87 km/h ± 1.26 km/h) was 11,8% lower compared to the field test (M =13.28 km/h ± 1.72 km/h), which was significant (p &lt; .001, d = -1.19). HR estimated by the watch at LT was 1,72% lower (p &gt; .05). LT data obtained in the field test showed greater overall variance. Conclusion Our results suggest sufficient accuracy of Fenix 7® LT estimates for recreational athletes. It can be assumed that for professional athletes, it would fail to provide the nuanced data needed for high-quality training management.