Test Performance Research Articles

Application and simulation of IEC water chillers for summer free cooling in data centers

Free cooling is regarded as the most effective way to reduce the energy consumption of the cooling system in data centers. This study proposes a novel water-medium indirect evaporative cooling (IEC) chiller used in a data center to achieve free cooling throughout the year as an alternative to electrical chillers. Field tests and numerical modeling of the IEC water chillers are both reported to evaluate the performance and efficiency. This paper first-time reports on the application of IEC water chillers to deliver year-round free cooling for a data center in Changji, China. The wet-bulb efficiency of the tested chiller is measured as 120% to 152.8% and the dew-point efficiency is 27% to 62.7%. A numerical model is established to verify the operating conditions, and some common operational optimizations are pointed out in this test for energy savings. PUE can be reduced to 1.212 after the optimization. More future performance predictions of the IEC water chillers are studied when the data center load rate increases and when the local weather changes in a year to discuss the year-round availability. For further study, the performance of IEC water chillers in different climate regions is also forecasted. The results indicate that it’s an effective way for IEC to achieve free cooling in regions where natural cold resources are abundant. In this study, the field test performance and prediction of IEC water chillers are provided as a typical and practical application as the natural cooling source in data centers in hot and dry areas.

Biochar derived from straw residue prepared via combined pre-treatment designed for efficient removal of tetracycline hydrochloride and sulfadiazine sodium salt

In this study, straw residue (SR) was prepared from corn straw by a combined pre-treatment method that involved both microbial treatment (Myrothecium verrucaria, Aspergillus niger, and Trichoderma reesei) and treatment with ρ-toluenesulfonic acid. After pre-treatment, the cellulose content of the residues reached 79.3 %, 72.1 %, 83.5 %, and 85.2 %, respectively. The results indicated that Aspergillus niger and Trichoderma reesei effectively destroyed the corn stover structure, improving the efficiency of the subsequent treatment. Following carbonation and activation processes, the SRs were converted into a series of biochars (ACCC, ACMC, ACTC, and ACNC) with large specific surface areas (2343, 2219, 2693, 2672 m2 g−1). The prepared biochars demonstrated excellent performance in adsorption tests performed using tetracycline hydrochloride (TC) and sulfadiazine sodium salt (SDZ) as adsorption models. The maximum adsorption capacities recorded for TC (908, 1117, 1216, and 1189 mg/g) and SDZ (930, 965, 1033, and 1083 mg/g) were higher than most of the other adsorbents. Furthermore, the potential adsorption mechanisms included pore filling, π-π interactions, hydrogen bonding, and electrostatic attraction. Even after 5 test cycles, the biochar retained over 75 % of its adsorption performance, highlighting its strong potential for applications in removing antibiotics from water.

Evaluation of hand-eye coordination fitness test performance in folk dance

Hand-eye coordination refers to the ability to perform tasks that require the simultaneous use of the hands and eyes, such as using visual-spatial perception to guide hand movements. An intricate comprehension of the brain’s functioning is vital for individuals to possess hand-eye coordination, which necessitates the integration of visual and motor abilities. The study assessed the level of hand-eye coordination fitness during folk dance. This study employed a quantitative methodology, with researchers utilizing a quasi-experimental approach evaluating the hand-eye coordination of participants in folk dance. This study comprised of seventh-grade students during the academic year 2023-2024. Researchers noted that individuals without previous performance experience encountered challenges in executing the dance action, while those who engaged in practice found it effortless. The researchers discovered a statistically significant disparity in the pretest and post-test scores of the respondents. The findings indicated that the respondents’ hand-eye coordination level may be improved and cultivated when executing a folk dance by diligently practicing the given pattern. The researchers suggested the utilization of the Drop Stick Game, Head Shoulder Knees and Ball, Chest Overhead Pass, and Clap-Catch Game. These four developmental exercises enhance hand-eye coordination and optimize performance. Additionally, it will aid students in cultivating hand-eye coordination, particularly during performances.

The Role of Hearing Aids in Improving Dual-Task Gait Performance in Older Adults With Presbycusis: A Cognitive and Motor Analysis.

Cognitive decline is a common challenge faced by older individuals with presbycusis; their performance on dual-task (DT) activities is generally lower compared to those without hearing loss. However, the influence of hearing aids on nonauditory cognitive decline in this population remains unclear. This study aims to investigate the effect of hearing aids on nonauditory DT performance in older adults with presbycusis. This study included older people with presbycusis who used hearing aids (P&HA group), those with presbycusis who did not use hearing aids (PoHA group), and a control group of healthy adults. Forward and backward digit span tests and timed up and go test (TUG) were administered to all individuals. TUG and motor and cognitive (forward and backward digit span) tasks were applied simultaneously to evaluate the participants' DT performance. The study comprised 60 individuals with presbycusis (19 females, 41 males; mean age: 73.23±6.49years) and 30 healthy adults (15 females, 15 males; mean age: 35.93±8.57years). Healthy adults performed better than the P&HA and PoHA groups in all the administered tests (p<0.05). There was a moderate negative relationship between the severity of hearing loss and the forward and backward digit span test performances (p<0.05). The P&HA group performed better than the PoHA group on the DT cognitive forward and backward digit span tests. The use of hearing aids and their proper fitting are important not only for improving communication skills and reducing listening effort but also for supporting nonauditory cognitive functions, minimizing the risk of falls during DT activities, and enhancing the overall quality of life.

Analysis of the relationship between upper body speed capacity and lower body strength of elite handball players specialized in winger position

Background and Study Aim. The physical demands of the winger position in elite handball require a unique combination of upper body speed and lower body strength. Therefore, identifying the optimal relationship between these two physical characteristics could improve performance for players in this role. This study aims to analyze the relationship between upper body speed capacity and lower body strength in elite handball players specializing in the winger position. Material and Methods. The study included 16 elite handball players specializing in the winger position from various teams in the National Handball League (Liga Zimbrilor). Four of these players were members of the Dinamo Bucharest team. Tests for evaluating the explosive strength of the lower limbs included the Squat Jump (SJ), Counter Movement Jump (CMJ), Counter Movement Jump with Free Arms (CMJb), and the maximum strength test (1RM) in squats. Specific technical training tests included triangular movement, a 30-meter sprint, and long-distance handball throws, focusing on speed and execution technique. Data analysis was conducted using KyPlot 6.0 software. Statistical indicators included median, standard deviation, coefficient of variation, and non-parametric Spearman correlation tests. Statistical significance was set at p &lt; 0.05. Results. The results show no statistically significant differences in lower limb strength between high-performance handball players (HPHP) and those specialized in the winger position (PSW) across various jump and squat tests (p &gt; 0.05). The Countermovement Jump (CMJ) test approached statistical significance (p = 0.084), while the CMJ with free arms (CMJb) and squat strength test did not show significant differences (p = 0.231 and p = 0.789, respectively). In the specific fitness tests, no significant differences were observed in the Triangle Movement test (p = 0.826), the 30-meter sprint (p = 0.404), or the handball throw test (p = 0.147). Correlation analysis indicated that squats and CMJb had positive correlations with improved performance in speed and distance tests, while CMJ showed a negative correlation with technical performance in agility tests. Conclusions. The findings suggest that lower limb strength and technical fitness are similar between elite handball players, regardless of specialization. This supports a unified training approach across player roles. However, targeted exercises like squats and CMJb may enhance specific performance aspects. These exercises improve dynamic strength and stability, which can benefit wingers' technical execution and speed.

Prevention of Overhead Shoulder Injuries in Throwing Athletes: A Systematic Review.

(1) Background: Shoulder pathologies are mostly found in overhead sports. Many risk factors have been identified, in particular a deficit in the kinetic chain. The aim of this review was to find out whether prevention by strengthening the kinetic chain can have an impact on the rate of shoulder injury in overhead pitching athletes. (2) Methods: A systematic review of the literature was carried out, including studies on the role of the kinetic chain in the prevention of overhead athletes. The studies used were works published over the last 10 years searched on PubMed, Cochrane Library, PEDro and Science Direct. They were also analyzed by methodological quality scales: the PEDro scale and the Newcastle-Ottawa scale. (3) Results: Eight studies met the inclusion criteria. The studies analyzed revealed a significant correlation between the use of the kinetic chain and the prevention of shoulder injuries, associating factors such as muscle strength, physical performance in tests (CMJ, FMS), static and dynamic balance and the ability to transfer energy from the lower to the upper body. (4) Conclusions: It is important to integrate core stability work and lower limb strengthening to minimize excessive stress on the shoulder complex, while optimizing force production and performance.

Stress distributions and stiffness anisotropy of circumferentially corrugated shells under uniform external pressure

As an excellent pressure structure, circumferentially corrugated shells have been widely used in many fields, such as ocean engineering and aerospace. At present, the circumferentially corrugated shells have only obtained good buckling performance in tests and finite element analysis. However, the corrugated shells have not been further analyzed in theory, and some new problems have been found in tests. The geometrical parameters of shell structures determine the stress distributions and stiffness anisotropy, and the von Mises stress and local stiffness determine the collapse form and collapse location. The relationship between them has not been explained. The study of this problem will be beneficial to establish the active design theory of the circumferentially corrugated shells. Therefore, this paper aims to investigate the von Mises stress and stiffness anisotropy of the circumferentially corrugated shells. Some corrugated shells with uniform thickness and some corrugated shells with non-uniform thickness are established. The parameters used to represent the corrugated structure and the degree of stiffness anisotropy are proposed. The influence of corrugation parameters on the stress distributions and stiffness anisotropy is studied by finite element method and theoretical analysis, the mechanical behaviors of two types of shells under uniform lateral external pressure is perfectly explained. It provides a direction for the design and optimization of these shells. In addition, a new circumferentially corrugated shell is proposed at the end of this paper. It has good mechanical properties, which will make it possible to further reduce its weight.

Enhancing Blockchain Security by Developing the SHA256 Algorithm

Security plays a vital role in various domains, including blockchain technology. The Blockchain serves as a secure data structure for storing transactional records. Hash functions are employed in cryptography to ensure integrity and authentication within the blockchain. The widely used SHA256 algorithm has faced recent attacks, prompting the development of stronger hash functions. This paper presents a novel modification approach to enhance the performance of SHA256 by introducing an extended mechanism for generating a 288-bit message digest and reducing the number of rounds to 44 instead of 64 while preserving the diffusion of data through its complex iterative process, which involves multiple rounds of bitwise and logical operations. The change makes sure that even small changes to the input data cause noticeable variations in the output hash, thereby maintaining cryptographic properties. The suggested hash function SHA288 achieves improved security, collision resistance, and preimage resistance, while maintaining a faster execution time compared to SHA256. The tables and tests conducted on the suggested algorithm have revealed its remarkable safety and robustness in countering attacks as well as demonstrated outstanding performance in random tests, which further enhances its security measures.

Evaluation of the Faecal Occult Blood Test as a Screening Tool for Periodontal Disease: A Case-Control Study.

To assess the feasibility of using a faecal occult blood test (FOBT) kit as a screening tool for periodontal disease. Additionally, the study aimed to evaluate the test's sensitivity and specificity while exploring the influence of factors like age, sex and the number of teeth on its performance. A prospective observational case-control study involving 150 participants divided into three groups on the basis of the basic periodontal examination index: healthy (n = 21), gingivitis (n = 52) and periodontitis (n = 77). Salivary occult blood tests were conducted using the Onsite FOB-Hi Rapid Test. Descriptive and analytical statistical analyses were performed using Fisher's exact test and chi-square tests. The FOBT kit demonstrated a sensitivity of 91% and a specificity of 100%. The number of teeth significantly influenced test results (p value = 0.021, chi-square). Age (p value = 0.09, chi-square) and sex (p value = 0.213, chi-square) did not significantly impact the test's performance. The FOBT kit demonstrates high sensitivity (91.3%) and specificity (100%) as a screening tool for periodontal disease. Its affordability and global availability make it suitable for detecting periodontal disease across different age groups, sexes and numbers of teeth.

A Newly Bio-Based Material for the Construction Industry Using Gypsum Binder and Rice Straw Waste (Oryza sativa)

Construction is one of the economic sectors with the greatest influence on climate change. In addition to working procedures, the primary carbon footprint is attributed to the choice of materials and the energy required for their manufacturing. The underlying idea of this study is to minimize the effects and offer new solutions to emerging problems in the quest for materials that can be deemed as natural, such as gypsum (calcium sulphate dihydrate) and rice straw (Oryza sativa). The acquisition of these materials involves a lower carbon footprint compared to the conventional materials. It is well known since ancient times that gypsum and cereal straw can be used in construction, with numerous examples still available. Cereal straw is one of the oldest construction materials, traditionally combined with earth and occasionally with certain binders, with it continuing to be employed in construction in many countries to this day. This work showcases the feasibility of producing stable prefabricated elements from straw waste with construction gypsum, addressing a significant environmental concern posed by the alternative of having to burn such materials. In this study, for the proposed bio-based material, specific tests, such as thermal conductivity, flexural and compressive strength, and fire resistance, were carried out to evaluate the principal physical and mechanical characteristics for different compositions of water, gypsum, and straw fiber samples. The results highlighted the good performance of the proposed materials in order to spread their use in the green building industry. The addition of straw fibers improved, in different ways, some important physical characteristics of these components so as to diminish environmental pollution and to obtain better material performance. The tests highlighted the different behaviors of the proposed material with respect to the different cuts of the straw and as well as the water/gypsum ratio; this is not very well understood and probably depends on the micro structure of the straw fibers. The blocks with raw straw showed a significant improvement in the breaking mechanism (1775.42 N) compared to the blocks with cut straw (712.26 N) when subjected to bending tests, and their performance in compression tests was also acceptable. Additionally, a very interesting reduction in thermal conductivity was achieved by incorporating rice straw (0.233 W/mK), and high fire exposure times were obtained, with gypsum preventing the spread of ignition in any type of fiber.

Study on Impact Resistance of Alkali-Activated Slag Cementitious Material with Steel Fiber

Alkali-activated slag cementitious materials (AASCMs) use alkaline activators to activate blast furnace slag and waste slag to replace traditional Portland cement, which can reduce CO2 emissions. An impact resistance test and scanning electron microscopy (SEM) microscopic performance analysis of alkali-activated slag cementitious material specimens with four different steel-fiber contents are performed. The effects of steel-fiber volume content and strain rate on the dynamic elastic modulus Ed, dynamic compressive strength σd, dynamic peak compressive strain εc, and energy absorption of the AASCM-SS are studied. The results indicate that the dynamic elastic modulus Ed, dynamic compressive strength σd, and energy absorption of the AASCM-SS increase with the increase of strain rate, and the dynamic peak compressive strain εc decreases with the increase of strain rate. The dynamic elastic modulus Ed, dynamic compressive strength σd, and dynamic peak compressive strain εc of the SS-AASCM increase first and then decrease with the increase of steel-fiber content. When the steel-fiber content is 0.5%, the σd and εc of the AASCM-SS are the highest, increased by 9.9% and 19.3%. The energy absorption of AASCM-SS increases with the increase of steel-fiber content. A dynamic constitutive model of the FR-AASCM considering the influence of damage, strain rate, and steel-fiber volume fraction is established. The proposed constitutive model is in acceptable agreement with the experimental AASCM-SS dynamic stress–strain curve, and the correlation coefficient is 0.91.

Special Series on the Wechsler Adult Intelligence Scale-IV Performances in Five Asian Countries: Summary of Findings, Clinical Implications, and Future Directions.

This special series of exploratory studies compared WAIS-IV performances in five Asian countries: Japan, South Korea, Taiwan, India, and Indonesia with the U.S. The studies examined cognitive profiles across age groups to develop hypotheses on how culture can impact cognition. This summary article integrates the findings from each study to determine similarities and differences across Asian countries and proposes possible underlying cultural factors impacting cognition. In each study, raw scores corresponding to a subscale score of 10 were scored with U.S. norms across all age groups. Index scores were calculated with the adjusted scale scores. The impact of education on test performances was determined by correlating WAIS-IV scores with a ratio of educational attainment for each country with the U.S. for each age group. Findings from each country were then integrated to develop hypotheses on cultural factors that impacted cognitive profiles. East Asian countries (Japan, South Korea, Taiwan) demonstrated weaker Verbal Comprehension Index scores and stronger Processing Speed Index scores than the U.S. sample, although the latter was moderated by age. East Asian countries demonstrated stronger performances on Perceptual Reasoning versus Verbal Comprehension tests. East Asians and the Java subset of the Indonesian sample demonstrated a pattern of stronger performances in younger versus older cohorts which was significantly correlated with educational attainment. Cultural factors impacting cognition were proposed. Clinical implications of the findings were discussed and directions for future studies to examine the relationship between culture and cognition were recommended.

Environmental impact analysis of ajmaline challenge protocols: a comparative assessment of carbon footprint reduction in Brugada Syndrome diagnosis

Abstract Background Climate change is an urgent public health crisis that significantly impacts disease development and health outcomes. The 2022 Lancet Countdown Report revealed that healthcare contributes with 5.2% of global emissions, prompting a call for environmentally conscious approaches. In this context, we explored the environmental impact of different ajmaline challenge protocols, aiming to contribute to a more sustainable medical landscape. Purpose This study aims to compare the carbon footprint of two ajmaline challenge protocols commonly used in diagnosing Brugada syndrome, an inherited cardiac disorder associated with sudden cardiac death. Methods We performed a retrospective and observational analysis of adult patients (pts) who underwent ajmaline testing between March 2020 and June 2023 in two hospitals. In Group A (infusion protocol), 1mg/kg of ajmaline diluted in 50 mL of 5% glucose solution was infused in 10 minutes, up to the target dose, until a positive result or termination criteria ensued. In Group B (bolus protocol), 10 mg of ajmaline were administered every 2 minutes, again up to the target dose of 1mg/kg (maximum of 100 mg) or test interruption was indicated. Greenhouse gas emissions resulting from material processing were estimated based on life cycle analyses of each product's composition. Material consumption, waste production, and direct measurement of weights were considered. Results A total of 101 pts were included, 49 pts in group A with a mean age of 47.3±14.3 years old and 52 patients in group B with a mean age of 43.9±16.6 years-old. No complications were observed in either group. Test performance was not evaluated, since both protocols have been previously validated. Group A, utilizing the infusion method, exhibited a higher environmental impact, producing 18.19 kg CO2eq, compared to 6.23 kg CO2eq (p&amp;lt;0.001) in Group B (bolus protocol). Group B not only demonstrated a 66% reduction in CO2eq emissions but also used significantly less plastic (16g vs 102g per test) and glass (1.58 kg vs 1,79Kg), emphasizing its environmental superiority. Conclusions Shifting from infusion to bolus in ajmaline challenge protocols results in a substantial reduction in carbon footprint. Our findings emphasize the potential impact of adopting more dematerialized approaches in cardiac testing, urging healthcare professionals to embrace sustainable practices. Despite the study's limited sample size, the global adoption of such environmentally friendly strategies promises significant positive effects on healthcare's environmental footprint.

ESC Heart Failure Association age-adjusted natriuretic peptide thresholds for a new diagnosis of heart failure: diagnostic accuracy study

Abstract Background Natriuretic peptide (NP) testing is an important part of the heart failure (HF) diagnostic pathway. The European Society of Cardiology (ESC) HF guidelines currently recommend a NT-proBNP cut-off &amp;lt;125pg/mL to rule out HF in the community.1 However, NP level increases with age and an NT-proBNP above 125pg/mL is common in older people in the general population. The ESC Heart Failure Association (HFA) recently published a practical algorithm for early diagnosis of HF recommending age-specific rule-in NT-proBNP thresholds: ≥125pg/ml for patients aged under 50 years, ≥250pg/ml for patients aged 50-75 years, and ≥500pg/ml for patients over 75 years (Figure 1).2 Purpose Our aim was to assess NT-proBNP test performance for HF diagnosis at the ESC HFA age-specific thresholds. Method We analysed our existing diagnostic accuracy study dataset containing primary care data from the Clinical Practice Research Datalink (CPRD) linked to inpatient Hospital Episode Statistics (HES) inpatient data between 2004 and 2018. NT-proBNP results were taken from the GP record (index test) and the primary outcome (reference standard) was a HF diagnostic code entered in CPRD or HES within six months of the test. NT-proBNP accuracy for HF was assessed by calculating sensitivity, specificity, positive predictive values (PPV), and negative predictive value (NPV). Receiver operating characteristic (ROC) curves were plotted to assess overall test performance. Results In total, 229,580 patients had an NP test and 21,102 (9.2%) were diagnosed with HF. The current ESC NT-proBNP threshold ≥125pg/mL had sensitivity 94.6% (95% confidence intervals [CI] 94.2 to 95.0), specificity 50.0% (95%CI 49.7 to 50.3), PPV 16.4% (16.1 to 16.6), NPV 98.9% (98.8 to 99.0)). Area under the ROC curve was 0.874 (0.871 to 0.877). Age-specific NT-proBNP thresholds performance: Below 50 years (≥125pg/mL): 32,882 people tested, HF prevalence 3.8%. Sensitivity 83.5 % (81.3 to 85.5), specificity 77.6% (77.2 to 78.1), PPV 13.0% (12.2 to 13.7), NPV 99.2% (99.0 to 99.3). 50 to 75 years ≥250pg/mL: 105,771 people tested, HF prevalence 9.8%. Sensitivity 88.5% (87.9 to 89.1), specificity 67.8% (67.5 to 68.0), PPV 23.1% (22.6 to 23.5), NPV 98.2% (98.1 to 98.3). Above 75 years ≥500pg/mL: 16,694 people tested, HF prevalence 17.5%. Sensitivity 84.4% (83.0 to 85.7), specificity 63.5% (62.7 to 64.3), PPV 32.8% (31.7 to 33.9), NPV 95.0% (94.6 to 95.5). Conclusion The age-specific NT-proBNP thresholds in the HFA practical algorithm had higher specificity so fewer people without HF would be referred, reducing demand for echocardiography and cardiology assessment overall meaning people with HF could be seen earlier. However, lower sensitivity means some cases of HF would initially be missed. NT-proBNP was a reliable ‘rule-out’ test at population level. The optimal NT-proBNP threshold will depend on the priorities and capacity of the national healthcare system.

Lindera aggregata improves intestinal function and alleviates depressive behaviors through the BDNF/TrkB/CREB signaling pathway induced by CUMS in mice

Depression is a common mental illness, which is highly related to intestinal motor dysfunction and causes a global burden of disease. Lindera aggregata (LA), a traditional medicinal herb, has been used to treat gastrointestinal disorders; however, the effect of LA on depression remains unclear. Here, we assessed the impact of LA on chronic unpredictable mild stress (CUMS)-induced depression in mice and explored the related mechanisms. The results showed that LA ameliorated depressive behaviors in mice exposed to CUMS, as evidenced by improved performance in the sucrose preference test, force swimming test, and open field test, as well as increased serum levels of adrenocorticotropic hormone and 5-hydroxytryptamine. In addition, LA increased the serum levels of D-xylose and ghrelin, indicating that LA can promote gastrointestinal motility. Additional studies revealed that LA relieved CUMS-induced hippocampal tissue damage, as shown by hematoxylin and eosin and Nissl staining. LA increased the expression levels of brain-derived neurotrophic factor (BDNF) and promoted the activation of tropomyosin receptor kinase B (TrkB) and cAMP response element-binding (CREB) in the hippocampus of CUMS-exposed mice or in corticosterone-injured HT22 cells. In conclusion, LA can improve CUMS-induced depressive behavior in mice, potentially through hippocampal neuroprotection mediated by the BDNF/TrkB/CREB signaling pathway, which also contributes to improved intestinal function.

Two-day cardiopulmonary exercise testing in long COVID post-exertional malaise diagnosis

BackgroundLong COVID patients present with a myriad of symptoms that can include fatigue, exercise intolerance and post exertional malaise (PEM). Long COVID has been compared to other post viral syndromes, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), where a reduction in day 2 cardiopulmonary exercise test (CPET) performance of a two-day CPET protocol is suggested to be a result of PEM. We investigated cardiopulmonary and perceptual responses to a two-day CPET protocol in Long COVID patients. Methods15 Long COVID patients [n=7 females; mean (SD) age: 53(11) yr; BMI = 32.2(8.5) kg/m2] performed a pulmonary function test and two ramp-incremental CPETs separated by 24 hr. CPET variables included gas exchange threshold (GET), peak oxygen uptake (V̇O2peak) and peak work rate (WRpeak). Ratings of perceived dyspnoea and leg effort were recorded at peak exercise using the modified 0–10 Borg Scale. PEM (past six months) was assessed using the modified DePaul Symptom Questionnaire (mDSQ). One-sample t-tests were used to test significance of mean difference between days (p<0.05). Results.mDSQ revealed PEM in 80 % of patients. Lung function was normal. Responses to day 1 CPET were consistent with the presence of aerobic deconditioning in 40 % of patients (V̇O2peak <80 % predicted, in the absence of evidence of cardiovascular and pulmonary limitations). There were no differences between day-1 and day-2 CPET responses (all p>0.05). ConclusionPEM symptoms in Long COVID patients, in the absence of differences in two-day CPET responses separated by 24 hours, suggests that PEM is not due to impaired recovery of exercise capacity between days.

The prognostic value of contrast stress echocardiography in a real-world population of symptomatic patients without known coronary artery disease

Abstract Background Coronary artery disease (CAD) is the leading cause of mortality and morbidity worldwide. In addition to diagnosis, non-invasive tests may also provide prognostic information useful in the risk stratification and management of CAD patients. Stress echocardiography (SE) is an accurate, non-invasive method for the detection of obstructive CAD. However, in real-world clinical practice the test performance may vary among different centres, depending on availability, local protocols, and operator expertise. Purpose To evaluate the prognostic value of contrast SE in a real-world population of symptomatic patients without known CAD. Methods This was a cohort follow-up study of patients without known CAD and symptoms of atypical chest pain, unexplained dyspnoea or palpitations who were referred to the echocardiography lab of a tertiary hospital for SE between January 2020 and December 2021. Patients with resting regional wall motion abnormalities were excluded. All patients underwent treadmill exercise stress echocardiography (ESE) or dobutamine stress echocardiography (DSE) if unable to exercise. Contrast agents were used in almost all patients (99%). The study population was followed-up for at least 2 years after SE by phone and/or electronic hospital records. Cardiac outcome was defined as anatomically or functionally significant stenosis on angiography, revascularization, acute coronary syndrome (ACS), or cardiac-related death. Results The study comprised 266 patients (mean age 58±12 years, 63% male) who underwent either ESE (58%) or DSE (42%). The patients' details are reported in Table 1. The most common indication for the exam was atypical chest pain, with a prevalence of 73%. SE exams were positive for inducible ischaemia in 14 (5%) patients. Symptoms during the exam were present in 3 (21%) patients with positive SE and 4 patients (2%) with negative SE (p=0.004). No serious complications (sustained ventricular tachycardia, myocardial infarction, or death) were recorded. During the follow-up (median 30, IQR 23–38 months), 264 patients (99%) were successfully contacted. Cardiac outcome occurred in 10 patients. Among 14 patients with positive SE, 8 underwent revascularization due to significant coronary artery stenosis. Among 250 patients with negative SE, 1 underwent revascularization due to significant coronary artery stenosis and 1 presented with ACS 13 months after the test (both patients underwent DSE). Negative predictive value was 99% over a median follow-up of 30 months, corresponding to an annualized event rate of 0.32% per year. A positive SE was significantly associated with cardiac outcome (log-rank test p&amp;lt;0.0001, Figure 1). Conclusion Contrast SE carries significant prognostic implications in symptomatic patients without known CAD. A positive test is strongly associated with the need for revascularization, while a normal test result has an excellent negative predictive value regarding cardiovascular morbidity and mortality.Figure 1

The Comparison of PISA 2015-2018 Mathematics Trend Items Based on Item Response Times

This study aims to explore the intricate relationship between students' response times, item characteristics, and the effort invested during the Programme for International Student Assessment (PISA) 2015 and 2018 cycles. Through the analysis of data obtained from 69 mathematics trend items administered in a computer-based format across both cycles, this research investigates the dynamics of students' response times and their implications on effort and item characteristics. Findings reveal a significant increase in students' mean response times in the 2018 cycle compared to 2015, indicating potentially heightened effort and solution behavior. Notably, item formats exerted a substantial influence on response times, with open-ended items consistently eliciting lengthier response times compared to multiple-choice items. Additionally, a correlation between response times and item difficulty emerged, suggesting that more challenging items tend to consume more time, possibly due to the complexity of involved cognitive processes. Item based effort, assessed through Response Time Fidelity (RTF) indices, highlighted that a majority of students exhibited solution behavior across both cycles to the items.. Moreover, a decrease in the proportion of students displaying rapid-guessing behavior was observed in the 2018 cycle, potentially reflecting increased engagement with the assessment. While providing insights into the interplay of response times, item characteristics, and effort, this study emphasizes the need for further exploration into the multifaceted nature of effort in educational assessments. Overall, this research contributes valuable perspectives on nuances surrounding test performance and effort evaluation within PISA mathematics assessments.

Effects of a 30-min rest with a nap chair on task performance, sleepiness, and neurophysiological measures in men with suspected brain fatigue: a randomized controlled crossover trial

BackgroundIt has been suggested that a short nap in the afternoon may improve sleepiness, alertness, and task performance. The present study evaluated the effects of a 30-min rest with a new nap chair on task performance, sleepiness, and neurophysiological measures.MethodsA randomized controlled crossover trial with a 1-week interval was carried out at the BOOCS Clinic Fukuoka in Japan. The subjects were male workers aged 20 to 64 years with suspected brain fatigue, which was defined by the Profile of Mood Status 2. The intervention was a 30-min rest with an office chair or a nap chair. The primary outcome was the performance in the Uchida-Kraepelin test. The secondary outcomes included the Karolinska Sleepiness Scale and 15-min heart rate variability (HRV). The changes after the nap-chair rest and office-chair rest were compared. Repeated measures analysis of variance with nesting was used in the statistical analysis.ResultsTwenty participants were eligible and entered the crossover trial. The overall 15-min score in the Uchida-Kraepelin test improved after the nap-chair rest and after the office-chair rest to almost the same extent (5.9 vs. 5.5 points, P = 0.68). The Karolinska Sleepiness score significantly decreased after the nap-chair rest, and the between-treatment difference in the decrease was highly significant (P = 0.0004). The average duration of sleep during rest was prominently longer in the nap-chair rest than in the office-chair rest (19.0 vs. 7.6 min, P = 0.002). No participants experienced REM sleep during the rest. LF and HF powers of the HRV were greater during the nap-chair rest than during the office-chair rest, the difference in the HF power being substantial.ConclusionA 30-min rest with the nap chair did not appreciably improve the performance in the Uchida-Kraepelin test as compared with the office-chair rest. The nap-chair rest induced a substantially longer sleep accompanied with a parasympathetic activation, thereby resulting in a material improvement in sleepiness after the rest.

Biomarker Assessment in Parkinson's Disease Dementia and Dementia with Lewy Bodies by the Immunomagnetic Reduction Assay and Clinical Measures.

Plasma biomarker assays provide an opportunity to reassess whether Alzheimer's disease, Parkinson's disease dementia (PDD), and dementia with Lewy bodies (DLB) plasma biomarkers are diagnostically useful. We hypothesized that immunomagnetic reduction (IMR) of plasma biomarkers could differentiate between patients with PDD and DLB and healthy patients when combined with established clinical testing measures. Plasma samples from 61 participants (12 PDD, 12 DLB, 37 controls) were analyzed using IMR to quantify amyloid-β 42 (Aβ42), total tau (t-tau), phosphorylated tau at threonine 181 (p-tau181), and α-synuclein (α-syn). Receiver operating characteristic curve (ROC) analysis was used to obtain sensitivity, specificity, and area under the ROC curve. Biomarker results were combined with clinical measures from the Unified Parkinson's Disease Rating Scale (UPDRS), Montreal Cognitive Assessment, and Hoehn-Yahr stage to optimize diagnostic test performance. Participants with PDD had higher α-syn than those with DLB and healthy participants and were distinguishable by their biomarker products Aβ42×p-tau181 and Aβ42×α-syn. Patients with DLB had higher p-tau181 than those with PDD and healthy participants and were distinguishable by their concentrations of α-syn×p-tau181. Plasma α-syn plus UPDRS versus either test alone increased sensitivity, specificity, and AUC when healthy patients were compared with those with PDD and DLB. Combined clinical examination scores and plasma biomarker products demonstrated utility in differentiating PDD from DLB when p-tau181 was combined with UPDRS, α-syn was combined with UPDRS, and α-syn×p-tau181 was combined with UPDRS. In this pilot study, IMR plasma p-tau181 and α-syn may discriminate between PDD and DLB when used in conjunction with clinical testing.