Standard Error Research Articles

Fast standard error estimation for joint models of longitudinal and time-to-event data based on stochastic EM algorithms

Summary Maximum likelihood inference can often become computationally intensive when performing joint modeling of longitudinal and time-to-event data, due to the intractable integrals in the joint likelihood function. The computational challenges escalate further when modeling HIV-1 viral load data, owing to the nonlinear trajectories and the presence of left-censored data resulting from the assay’s lower limit of quantification. In this paper, for a joint model comprising a nonlinear mixed-effect model and a Cox Proportional Hazards model, we develop a computationally efficient Stochastic EM (StEM) algorithm for parameter estimation. Furthermore, we propose a novel technique for fast standard error estimation, which directly estimates standard errors from the results of StEM iterations and is broadly applicable to various joint modeling settings, such as those containing generalized linear mixed-effect models, parametric survival models, or joint models with more than two submodels. We evaluate the performance of the proposed methods through simulation studies and apply them to HIV-1 viral load data from six AIDS Clinical Trials Group studies to characterize viral rebound trajectories following the interruption of antiretroviral therapy (ART), accounting for the informative duration of off-ART periods.

BIOS-04. THERAPIES FOR LEPTOMENINGEAL DISEASE: A NETWORK META-ANALYSIS

Abstract INTRODUCTION Leptomeningeal disease (LMD) has limited head-to-head comparison of available therapies, including systemic chemotherapy (SysCT), intrathecal (IT) or intraventricular therapy (ITV), whole-brain radiotherapy (WBRT), or cranio-spinal irradiation (CSI). No network meta-analysis (NMA) of randomized controlled trials (RCTs) of LMD has been reported so far. METHODS NMA was conducted using published LMD RCTs and reported following PRISMA-NMA guidelines. Primary outcome was survival, assessed using hazard ratios (HRs) and 95% confidence intervals (95%CI). Survival times were converted to HRs under exponential distribution assumption. LogHR standard errors were calculated using deaths per RCT arm. P-scores were used to estimate probability of treatment being superior. Analysis was performed in R using frequentist approach, followed by back-transforming logHRs for indirect and direct comparisons. Incremental effects of individual treatment components were estimated using additive model. Heterogeneity and inconsistency were assessed using tau-squared (τ²), I-squared (I²), and Q-statistics. Analyses were performed separately for main subnetwork with disconnected subnetworks accommodated in additive model. RESULTS Seven studies were included, incorporating 7 pairwise comparisons and 9 treatments. 3 subnetworks were identified. Primary subnetwork analysis included 5 studies. Compared to SysCT±RT (reference), logHRs (95%CI) under random effects model were: IT/ITV DepoCyt±SysCT±RT -0.094(-0.468,0.281); IT/ITV methotrexate(MTX)±cytarabine(AraC)±SysCT±RT 0.8567(0.066,1.647). IT/ITV MTX±SysCT±RT 0.318(-0.163,0.798); ITV Thiotepa±SysCT±RT 0.438(-0.294,1.169). Heterogeneity and inconsistency were not detected (τ²=0,I²=0%,Q-statistic=0.57,P=0.45). P-scores were highest for IT/ITV DepoCyt±SysCT±RT (0.894), followed by SysCT±RT (0.769). Disconnected-component-NMA demonstrated incremental logHR: AraC 0.539(-0.347,1.425); IT/ITV DepoCyt 0.052(-0.566,0.670); IT/ITV MTX 0.179(-0.484,0.840); ITV thiotepa 0.298(-0.767,1.362); proton CSI -0.250(-0.726,0.225). No component demonstrated statistically significant incremental benefit, with moderate heterogeneity and adequate fit present (τ²=0.1017,I²=57%,Q-statistic=4.65,P=0.098). CONCLUSIONS IT/ITV DepoCyt±SysCT±RT and SysCT±RT were found most effective. Lack of significant incremental benefit warrants evaluating older therapies in contemporary RCTs.

Longissimus from Berkshire pigs in a small-scale supply chain have increased oxidative metabolism, tenderness and water-holding capacity, compared with Large White × Landrace pigs in a modern commercial supply chain

Context Selection for leanness in the modern Australian pig has resulted in inconsistent quality, including a lack of pork tenderisation during ageing. Inconsistent quality is potentially a result of differences in supply chain and breed as well as the variation in muscle fibre-type proportion in pork longissimus. Aim The aim was to investigate differences in fibre-type proportion and pork quality between Large White-Landrace pigs in a large supply chain and Berkshire pigs processed in a small supply chain. Methods Pigs (n = 22) from two suppliers with different breeds (Supplier 1, Large White × Landrace, SC1-LWLR, n = 12, modern commercial pigs; Supplier 2, Berkshire, SC2-Berk, n = 10, heritage pigs) were slaughtered and samples from the longissimus were extracted at 3, 24, and 48 h postmortem for enzyme and pH analyses. Longissimus samples were subjected to ageing for either 2 or 16 days postmortem (Day 2, Day 16), assessed for colour, muscle fibre-type proportion (%), muscle fibre diameter (μm), water-holding capacity (purge, % and cook loss, %), Warner–Bratzler peak shear force (WBSF, N), and protein denaturation temperature using differential scanning calorimetry (DSC, peak temperature, °C). Key results SC1-LWLR had higher purge than SC2-Berk (2.85% and 1.83% respectively; standard error of the difference (SED) = 0.33; P = 0.003), higher cook loss on Day 16 (24.63% and 16.79% respectively; SED = 1.62; P = 0.017) and higher WBSF on Day 2 and Day 16 (Day 2, 30.9 N and 26.7 N respectively; Day 16, 28.6 N and 22.0 N respectively; SED = 0.98, interaction P = 0.003). SC1-LWLR had a lower proportion of Type I (10.1% vs 16.0%; SED = 0.51) and Type IIA (14.0% vs 22.0%; SED = 0.77) and a higher proportion of Type IIB (75.9% vs 62.0%; SED = 0.74) (P < 0.001 for all) fibres. SC1-LWLR had lower DSC temperatures for two peaks. SC2-Berk had higher citrate synthase activity (P = 0.003) and glycolytic potential (P < 0.001) than SC1-LWLR. Conclusions SC2-Berk longissimus had improved quality compared with SC1-LWLR pork, most likely owing, in part, to higher proportion of oxidative and intermediate fibres in the Berkshires. However, effects of differences in environmental conditions and/or processing conditions cannot be ruled out. Implications The experiment increased our understanding of how variation in supply chains and muscle fibre-type proportion can impact the production of consistently high-quality pork.

The Moderating Roles of Economic Complexity in the Entrepreneurship‐Sustainable Environment Nexus for the Gulf Cooperation Council Economies

ABSTRACTThere are conflicting views on the effect of business and entrepreneurial activities on environmental degradation in developing economies. However, none of this study examines whether economic complexity can serve as a policy tool for mitigating the effect of entrepreneurial business activities on a sustainable environment. Economic complexity consists of the structural and economic transformation process from a simple production system to a more complex and innovation‐based one. It predicts the variations in income level and its impact on the choice of goods being produced in an economy. This study examines the moderating effect of economic complexity on the link between entrepreneurship and sustainable environment in Gulf Cooperation Council (GCC) countries from 2006 to 2020. It further examines the validity of the Entrepreneurial Environmental Kuznets Curve (EEKC). The study uses the Driscoll‐Kraay standard error fixed effect, Panels Corrected Standard Errors (PCSE), method of moment quantile regression and Dumitrescu–Hurlin causality that are robust to heteroscedasticity, cross‐sectional dependency and other pitfalls of least square estimating technique. The results validate the inverted U‐shaped EEKC hypothesis across all the quantiles. Economic complexity increases ecological degradation at the lower quantile levels, while it decreases environmental footprint at the upper quantiles. Furthermore, economic complexity moderates the detrimental impact of entrepreneurial activity on the environment at the higher quantiles. A two‐way relationship is established between entrepreneurial activity and the environment, while one one‐way connection from economic complexity to the environment was found. The study recommends that policymakers should encourage innovative rather than necessity entrepreneurs. Entrepreneurs should be encouraged to engage in business activities that are friendly toward preserving the ecological environment, and green innovative activities should be prioritised in their entrepreneurial activities.

Navigating Carbon Peaking and Neutrality in MENA: The Impact of Foreign Direct Investment and Trade Openness Using Panel PCSE and FGLS Techniques

ABSTRACTIn response to the global challenge of climate change and the drive towards carbon neutrality, this study investigates the effects of foreign direct investment (FDI) and trade openness (TO) on carbon emissions (CEM) within the Middle East and North Africa (MENA) region. The research spans 18 countries from 1990 to 2022, focusing on Sustainable Development Goal 13. Utilizing Porter's hypothesis and the Environmental Kuznets Curve (EKC) theory, the study applies quantitative methods including panel corrected standard errors (PCSE) and feasible generalized least squares (FGLS) to ensure robustness. To address potential endogeneity, two‐stage least squares and lagged effect estimations are employed. The findings reveal that both FDI and TO are associated with reduced CEM, indicating positive environmental impacts. Also, the pairwise causality tests show bidirectional causality between FDI, TO, and CEM, while a unidirectional causality is found from industrialization (IND) and energy consumption (EC) to CEM. These results underscore the importance of integrating FDI and TO into strategies for achieving carbon neutrality and advancing sustainable development goals, offering actionable insights for policymakers.

Age-Related Differences and Reliability of a Field-Based Fitness Test Battery in Young Trained Footballers: The Role of Biological Age

Background: the purpose of this study was to analyze the reliability of a field-based fitness test battery in young trained football players, according to biological age. Methods: 197 young trained football players (12–19 years old) participated in the study. We measured anthropometric measurements (i.e., height, sitting height, length leg, and body mass), a bilateral vertical jumping test (CMJ), a progressive loading test of squats and hip thrust, acceleration and speed tests (10 m and 30 m sprint tests), a change-of-direction ability test (V–cut test), and a cardiorespiratory fitness test (30–15 intermittent fitness test). Statistical data are shown as the mean ± standard deviation by PHV group in tests and retests. Test reliability was assessed through the intraclass correlation coefficient (ICC), with an ICC above 0.9 being considered high. To evaluate accuracy and repeatability, standard error of measurement, coefficient of variation, and minimum detectable change at 90% were determined and Bland–Altman diagrams were used, establishing a statistical significance of p < 0.05. Results: All of the tests showed non-significant differences between the test and retest in the pooled sample (p > 0.05). Furthermore, all of them presented a trivial effect size (<0.2) and high intraclass correlation coefficients (>0.9), which indicates the high reproducibility of the tests, despite some of them presenting a significant difference between trials (i.e., the CMJ, 10 m sprint, V–cut, and squat tests). Low measurement errors were found for all tests (coefficient of variation [CV] = 4.39–9.39), except for the CMJ and the progressive loading test for squat and hip thrust exercises (CV = 12.2–21.11). Similar results were found irrespective of biological age group. Conclusions: All tests were reliable for the pooled sample as well as for the biological age groups.

Unraveling Plastic Pollution in Protected Terrestrial Raptors Using Regurgitated Pellets

The threat of plastic pollution has escalated to unprecedented levels, with particular concern surrounding microplastics (MPs) and artificial fibers or particles (AFs) due to their wide distribution across ecosystems and their bioavailability to wildlife. Although research on the impact of plastic on wild birds is rapidly growing, knowledge of terrestrial species remains limited, especially regarding raptors, which have been significantly understudied. Here, we investigated the prevalence of MPs and AFs in regurgitated pellets from six protected terrestrial raptor species, namely the Cinereous Vulture (Aegypius monachus), the Bonelli’s Eagle (Aquila fasciata), the Little Owl (Athene noctua), the Lesser Kestrel (Falco naumanni), the Red Kite (Milvus milvus), and the Barn Owl (Tyto alba), collected between 2022 and 2023. Our analysis revealed that 68% of the pellets contained MPs (47 out of 69), and 81% contained AFs (56 out of 69). Additionally, two macroplastics were found inside the pellets: a cable tie in a Red Kite and a bird identification ring in a Cinereous Vulture. The concentrations (mean ± standard error of the mean) were 2.39 ± 0.39 MPs/pellet and 5.16 ± 0.72 AFs/pellet. The concentration of MPs and AFs varied significantly among some of the studied species; however, no significant differences were observed among urban, rural, and protected areas. This could indicate that contamination levels are mainly related to the type of species. Fibers emerged as the predominant contaminant shape, with six different polymers identified, among which PET, PE, and acrylics were the most prevalent. These findings highlight that plastic pollution has reached protected terrestrial raptors and that the impact of plastic on their life cycles needs to be assessed.

Effect of Interrupting Prolonged Sitting with Frequent Activity Breaks on Postprandial Glycemia and Insulin Sensitivity in Adults with Type 1 Diabetes on Continuous Subcutaneous Insulin Infusion Therapy: A Randomized Crossover Pilot Trial.

Objective: This study examined acute effects of interrupting prolonged sitting with short activity breaks on postprandial glucose/insulin responses and estimations of insulin sensitivity in adults with type 1 diabetes (T1D). Method: In a randomized crossover trial, eight adults (age = 46 ± 14 years [mean ± SD], body mass index [BMI] = 27.2 ± 3.8 kg/m2) receiving continuous subcutaneous insulin infusion (CSII) therapy completed two 6-h conditions as follows: uninterrupted sitting (SIT) and sitting interrupted with 3-min bouts of simple resistance activities (SRAs) every 30 min. Basal and bolus insulin were standardized across conditions except in cases of hypoglycemia. Postprandial responses were assessed using incremental area-under-the-curve (iAUC) and total AUC (tAUC) from half-hourly venous sampling. Meal-based insulin sensitivity determined from glucose sensor and insulin pump (SiSP) was assessed from flash continuous glucose monitor and insulin pump data. Outcomes were analyzed using mixed models adjusted for sex, BMI, treatment order, and preprandial values. Results: Glucose iAUC did not differ by condition (SIT: 19.8 ± 3.0 [estimated marginal means ± standard error] vs. SRA: 14.4 ± 3.0 mmol.6 h.L-1; P = 0.086). Despite CSII being standardized between conditions, insulin iAUC was higher in SRA compared to SIT (137.1 ± 22.7 vs. 170.9 ± 22.7 mU.6 h.L-1; P < 0.001). This resulted in a lower glucose response relative to the change in plasma insulin in SRA (tAUCglu/tAUCins: 0.32 ± 0.02 vs. 0.40 ± 0.02 mmol.mU-1; P = 0.03). SiSP was also higher at dinner following the SRA condition, with no between-condition differences at breakfast or lunch. Conclusion: Regularly interrupting prolonged sitting in T1D may increase plasma insulin and improve insulin sensitivity when meals and CSII are standardized. Future studies should explore underlying mechanistic determinants and the applicability of findings to those on multiple daily injections. Trial Registration: Australian and New Zealand Clinical Trial Registry Identifier-ACTRN12618000126213 (www.anzctr.org.au).

Reliability and Validity of the L Test in Persons With Multiple Sclerosis.

The L Test has been developed to assess balance and gait disorders. Our aim in this study was to estimate the test-retest reliability and validity of the L Test when used with 82 persons with multiple sclerosis (PwMS). For these participants, we examined the degree of agreement between the results of a first and second administration of the L Test (separated by one day), using Bland-Altman analysis and intra-class correlation coefficients (ICCs). We computed minimal detectable change (MDC) and standard error of measurement (SEM) values for the L Test and evaluated concurrent validity by correlating L Test results with the Timed Up and Go test (TUG) and the 10-minute Walk Test (10MWT). Prior to administering these measurements, we randomized the sequence of the test administrations to our participants. The Bland-Altman analysis showed that L Test was reproducible, with upper and lower limits of agreement of 0.99 and -1.45 seconds, respectively. The L Test demonstrated excellent test-retest reliability, with an ICC value of 0.996 (95% CI: 0.994-0.998). Cronbach's alpha coefficient was 0.996. The performance of the L Test is measured by seconds required to complete the task, and we found the L Test SEM value to be 0.35 seconds, and its MDC value to be 0.97 seconds. The L Test showed a strong correlation with both the TUG test (rho = 0.936; p < .001) and the 10MWT (rho = 0.925; p < .001). We concluded that the L Test is a reliable and valid \ tool for assessing functional mobility and balance in PwMS.

Identification of Novel Genetic Loci Affecting Age at Onset of Parkinson's Disease: A Genome-wide Association Study.

The age at onset (AAO) of Parkinson's disease (PD) varies widely among individuals and significantly influences disease progression and prognosis. However, few genome-wide association studies (GWASs) have investigated genetic variants determining AAO, particularly in East Asian populations. To identify single-nucleotide polymorphisms (SNPs) affecting AAO of PD in Korean patients. We conducted a GWAS on AAO of PD in 1048 Korean patients using sex-adjusted linear regression models. Additionally, we conducted downstream analyses of our primary GWAS results. rs2134545 demonstrated genome-wide significance (β = -2.459; standard error [SE] = 0.851; P = 1.898 × 10-8) and is an intergenic SNP near the ALCAM gene associated with an average AAO reduction of 3.47 years. Additionally, rs4366309 (LYST; MIR1537) demonstrated suggestive significance (β = 2.949; SE = 1.072; P = 8.68 × 10-8) and was associated with an average delay of 3.05 years. The polygenic risk score based on known PD risk loci also affected the AAO for European and Korean PD risk loci, respectively (β = -0.149; P < 0.001 and β = -0.096; P = 0.002). However, the proportion of variance was small (r2 = 0.022 and 0.009, respectively). We identified a novel SNP associated with the AAO of PD near the ALCAM gene, distinct from previously reported PD risk loci. These findings need further functional validation; however, they suggest unique genetic pathways influencing the AAO of PD and highlight the need for further research in diverse populations. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Progesterone and Estradiol Levels Associated with Concussion and Clinical Outcomes and Recovery in Female Athletes and Cadets.

Introduction: Female athletes are underrepresented in concussion research, and few studies have investigated associations of ovarian hormones with concussion outcomes. This study explored associations of concussion with levels and variability of progesterone, estradiol, and their ratio (P/E) and examined relationships of hormone levels with clinical measures and recovery after concussion in CARE Consortium female athletes and cadets.Methods: Female participants enrolled (n = 749) at pre-injury baseline. Participants with concussion (mean age 19.34 years; n = 130, 90 athletes, 40 non-athlete cadets) completed one or more visits at non-standardized times of day: immediately post-injury, 24-hours post-injury, upon initiating the return-to-play protocol (Init RTP), and seven days following unrestricted return-to-play (PRTP). Controls (mean age 19.85 years; n = 67, 61 athletes, 6 non-athlete cadets) completed similar visits. Linear mixed models and general linear models tested associations of hormone levels and/or variation with concussion status, symptoms, and recovery, controlling for self-reported birth control use at pre-injury baseline.Results: Female participants with concussion had higher progesterone levels relative to controls on average across all visits (mean difference (ln ng/mL) (standard error) MD = 0.26(0.08), t(193) = 3.03, p = 0.003). Those with concussion had elevated estradiol at 24 hours (MD = 0.27(0.09), t(506) = 3.04, p = 0.02), Init RTP (MD = 0.38(0.09), t(508) = 4.29, p < 0.001), and PRTP (MD = 0.30(0.09), t(515) = 3.25, p = 0.01) relative to pre-injury baseline, and compared to controls at Init RTP (MD = 0.35(0.12), t(429) = 2.78, p = 0.006). Concussed participants had a lower range of estradiol over 7-28 days than controls (B(SE) = -0.24(0.09), F(1,145) = 6.43, p = 0.01). Acutely after concussion, estradiol was positively associated with Brief Symptom Inventory Global Severity Index scores (B(SE) = 0.29(0.12), F(1,102) = 5.60, p = 0.02). No significant relationships were found between hormones and recovery.Conclusions: These results, which warrant further research, suggest ovarian hormones may be associated with concussion and psychological symptom severity post-concussion.

Is Binary Grading Better Than WHO System for Grading Epithelial Dysplasia? A Systematic Review and Meta-Analysis.

This meta-analysis summarizes the current evidence on the intra- and inter-observer agreement between WHO and the binary grading systems used to assess epithelial dysplasia (ED). A systematic search for observational studies that compared the level of agreement among pathologists between WHO and binary grading systems for ED was conducted using three databases: Medline, Scopus, and EBSCOhost. For the meta-analysis, summary estimations of kappa value (κ) and standard error (SE) were utilized. The pooled analysis of observations by 46 pathologists from a total of eight studies showed better interobserver agreement in the interpretation of ED for the binary system (κ = 0.31; 95% confidence interval [CI], 0.23-0.40) in comparison with the WHO (κ = 0.14; 95% CI, 0.10-0.19). The intra-observer agreement was reported only by five studies and was also found to be higher for the binary system (κ = 0.44; 95% CI, 0.31-0.57) compared to the WHO (κ = 0.25; 95% CI, 0.11-0.39). Our results validate that the binary system has better overall intra-observer and interobserver agreement than the WHO system. Further studies with larger cohorts are mandatory before clinically relevant conclusions are drawn, as evidence remains inadequate.

FDI, industrialisation and environmental quality in SSA—the role of institutional quality towards environmental sustainability

In light of the quest to achieve economic development without compromising environmental quality, we empirically examine whether institutional quality (INSQY) can help moderate the possible harmful effects of foreign direct investments (FDI) and industrialisation on environmental quality in sub-Saharan Africa (SSA). We utilise the Driscoll and Kraay standard error estimation technique on a panel of 45 SSA countries from 2000 to 2019. The results indicate that FDI and industrialisation generally have a significant harmful effect on the environment. Our findings reveal that INSQY directly promotes environmental quality. Notably, the results confirm that INSQY plays a stimulating role in mitigating the adverse effects of FDI and industrialisation on environmental quality. The results further validate the environmental Kuznets curve (EKC) hypothesis in SSA. These findings contribute to environmental sustainability literature and offer policymakers insights on how INSQY can enhance environmental quality. Our empirical results are also robust to different estimation techniques, such as the two-stage least squares. We recommend SSA leaders strengthen institutional capacities, enforce environmental regulations, and implement strict policies to ensure environmental quality while promoting industrialisation and FDI inflows.

Austrian FDI in Asian economies: Does knowledge capital matter?

PurposeWhile Austrian foreign direct investment (FDI) in Asian economies experiences a rising trend, the following question arises: Why does Austria invest more in certain economies over others? This study intends to assess the factors that drive Austrian investment in Asian economies.Design/methodology/approachBased on the ownership, location and internalization framework and the knowledge capital approach, this study hypothesizes that knowledge capital significantly attracts FDI from Austria. Meanwhile, this study applies the panel-corrected standard error method to analyze data for 11 Asian economies from 1990 to 2022.FindingsAfter considering endogeneity, the results show a positive and significant correlation between expenditure in research and development per gross domestic product (GDP) in the host economies and FDI inflow from Austria. In addition, the study reveals that factors such as market size, trade openness and natural resources in the host economies significantly influence Austria’s FDI, which indicates that Austrian investors fall into the three main FDI typologies: market-seeking, resources-seeking and efficiency-seeking.Originality/valueThis study fills the literature gap by becoming the first to analyze the determinants of Austrian FDI in Asian economies, thus enriching our understanding of Austria’s global investment pattern.

Do sustainable business practices enhance firm profitability? An empirical study of Indian listed companies

This study employs a panel data model to examine the impact of sustainable business practices on profitability in the Indian market, focusing on 49 companies listed in the S&amp;amp;amp;P BSE ESG 100 index from 2015 to 2022. Sustainable business practices are measured by ESG composite scores and individual environmental, social, and governance scores. Profitability is represented by return on equity and return on assets. Utilizing the Panel Corrected Standard Error technique to address data issues like autocorrelation and heteroscedasticity, the study finds that sustainable business practices insignificantly impact profitability. However, the social pillar has a significantly positive correlation with return on assets, with each unit improvement in the social score resulting in a 0.1323 increase in return. Conversely, the governance pillar negatively impacts return on assets, with each unit increase in governance score resulting in a decrease of 0.1527 units in profitability. Interestingly, larger companies experienced reduced returns on both assets and equity, as financial risk also lowered returns. These findings emphasize the relevance of companies’ socially responsible behavior, suggesting that managers and investors should prioritize sustainable practices for long-term benefits. Additionally, the findings advocate for robust regulatory frameworks focused on sustainability.

Cultural Tension and Large- and Small-Scale Internal Conflicts

This study analyzes how cultural tensions (i.e., ethnic and religious) affect various internal conflicts (e.g., civil war to civil disorder) across different regions. The study also examines the role of governance in mitigating the effects of cultural tensions on the emergence and escalation of conflict. The comprehensive study has 136 countries from 1990 to 2021, and panels are separated by region and OECD status. The study uses two-way fixed effects with Driscoll and Kraay standard errors to account for heteroscedasticity, autocorrelation, and cross-sectional dependence. Although there are some regional variations and nuances, the results indicate cultural tensions are significant determinants of (1) the broad measure of internal conflict, (2) civil wars/coups d’état, and (3) political violence/terrorism. Therefore, one implication is that cultural tension continues to drive internal conflict. A second implication is that even in OECD countries, where institutions and governance structures are robust, cultural tensions can still significantly contribute to the emergence and risks of internal conflict. However, ethnic and religious tensions are less influential in smaller-scale conflicts, such as civil disorders, where government stability is a more important determinant. Furthermore, the study finds that government strength is vital in moderating all forms of internal conflict, indicating that even moderate cultural tensions can escalate into significant conflicts in the presence of weak governance. The study underscores the ongoing importance of addressing ethnic and religious tensions. Policy recommendations to reduce cultural tensions include (1) promoting cultural inclusiveness within societal/political dimensions, (2) promoting tolerance, (3) allowing some autonomy to cultural enclaves, and (4) actively monitoring cultural tensions and policy initiatives.

A note on potential gains in precision of radiation risk estimates from joint analysis.

In estimating radiation-related risk of cancer and other diseases based on the RERF Life Span Study (LSS), joint analyses can be performed where multiple health outcome endpoints are combined in the same model, allowing some parameters to be estimated in common among all endpoints with possible increase in precision of radiation risk and other model parameter estimates. Using as a basis excess relative risk (ERR) and excess absolute risk (EAR) models of the type commonly used in analysis of LSS data at RERF, we use maximum likelihood theory to compute the asymptotic relative standard error of endpoint-specific radiation effect and other parameter estimates using joint analyses as compared to traditional independent analysis. We show that some gains in precision of endpoint-specific radiation risk parameter estimates can be achieved by sharing effect modifier and other model parameters, but only small or negligible gains in precision are achieved for endpoint-specific background modifying or effect modifying parameters when other model parameters are shared. The magnitude of the precision gain for radiation risk estimates depends on the number of endpoints, the baseline incidence rate of the endpoint, and the type of model being used.

Cross-Validation of Equations for Estimating 1 Repetition Maximum From Repetitions to Failure for the Bench Press and Leg Extension.

Roberts, TD, Smith, RW, Arnett, JE, Ortega, DG, Schmidt, RJ, and Housh, TJ. Cross-validation of equations for estimating 1 repetition maximum from repetitions to failure for the bench press and leg extension. J Strength Cond Res XX(X): 000-000, 2024-Eighteen previously published equations (EQs) that estimate 1 repetition maximum (1RM) from repetitions to failure (RTF) were cross-validated for the bench press (BP) and leg extension (LE) movements. Forty-three recreationally active men (age: 20.58 ± 1.47 years; body mass [BM]: 81.66 ± 13.65 kg) completed a 1RM test and RTF at 80% of the 1RM test for the LE, and 39 of the 43 men (age: 20.61 ± 1.48 years; BM: 83.58 ± 12.73 kg) completed the same tests for the BP. The EQs were categorized as generic (the source did not indicate its applicability for a specific movement) or movement-specific (BP-specific and LE-specific EQs). The generic EQs were cross-validated for both movements, whereas the BP-specific and LE-specific EQs were cross-validated for their respective movements only. The cross-validation criteria included calculations of the constant error (CE) (mean differences between estimated and measured 1RM), Pearson Correlation Coefficient, standard error of the estimate, and total error. The level of significance was set at p ≤ 0.05. After the initial cross-validation analyses of the previously published EQs, the most accurate EQs were modified by subtracting their cross-validation CE from the original EQ to improve their accuracy for estimating BP and LE 1RM by eliminating systematic error. The modified EQs were then cross-validated using the same statistical procedures. Based on the cross-validation analyses, we recommend the following EQs: BP 1RM = (RTF0.1 × weight) + 1.49 and LE 1RM = (RTF0.1 × weight) + 1.06 using weights that result in 4-10 RTF.

Reliability, measurement error, and validity of the Arabic version of the Patient-Specific Functional Scale in patients with upper extremity musculoskeletal disorders.

To evaluate the measurement properties of the Arabic Patient-Specific Functional Scale (PSFS) in individuals with upper extremity musculoskeletal disorders. Participants with upper extremity musculoskeletal disorders (N = 139) completed the PSFS, Upper Extremity Functional Index (UEFI), the Disabilities of the Arm, Shoulder and Hand (DASH), Numeric Pain Rating Scale (NPRS) and the Global Assessment of Function scale (GAF). The same outcome measures were completed again with one week in addition to the Global Rating of Change Scale. The test-retest reliability, measurement error, floor and ceiling effects, and construct validity of the PSFS were examined. The PSFS demonstrated very good test-retest reliability (ICC2,1 = 0.82; 95% CI: 0.71-0.88), with no evidence of floor or ceiling effects. The standard error of measurement was determined to be 0.74 while the minimal detectable change was 1.73 points. The PSFS demonstrated significant negative correlation with DASH, NPRS (-0.58, -0.35), and significant positive correlation with the UEFI and GAF (0.56, 0.50). The PSFS demonstrated statistically higher correlation with the DASH and UEFI compared with the NPRS (p < 0.004) supporting our predefined construct validity hypotheses. The Arabic PSFS is an applicable, reliable, and valid outcome measure of upper-extremity activity limitations for patients with upper extremity musculoskeletal disorders.

Impact of Shadow Economy on Tax Revenue in Sub-Saharan Africa

This study tends to focus on how shadow economy and trade openness influence tax revenue in the Sub-Saharan Africa (SSA). The study used four SSA countries to test this relationship from 1991 to 2017. The study employs pool OLS with robust standard error to address the potential threat of heteroscedasticity. The result from this estimation indicate that shadow economy diminished the amount of tax revenue generated by these countries. Thus, the study recommends that appropriate measures should be put in place to curtail the size of the shadow economy because of its detrimental effects on tax revenue.