Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in ...SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb. This study used Monte Carlo data simulation techniques to evaluate sample size requirements for common applied SEMs. Across a series of simulations, we systematically varied key model properties, including number of indicators and factors, magnitude of factor loadings and path coefficients, and amount of missing data. We investigated how changes in these parameters affected sample size requirements with respect to statistical power, bias in the parameter estimates, and overall solution propriety. Results revealed a range of sample size requirements (i.e., from 30 to 460 cases), meaningful patterns of association between parameters and sample size, and highlight the limitations of commonly cited rules-of-thumb. The broad “lessons learned” for determining SEM sample size requirements are discussed.
The purpose of this study was to investigate the influence of solid lubricants on the friction and wear behavior of Cu-based thermal-sprayed coatings. The ultimate goal was to identify the friction ...coefficient behavior of these systems as well as establish an understanding of the interfacial processes. Experiments were conducted using a flat-on-flat apparatus with uncoated pins against Cu-based thermal-sprayed systems with and without molybdenum disulfide (MoS
2
) as the solid lubricant. The results showed that the coefficient of friction for the samples with Cu-Al was similar to that of the uncoated system. The unlubricated systems (i.e., Cu-Al coated and uncoated) showed higher friction values compared with the one with the MoS
2
lubricant. Additional testing with re-application of the MoS
2
lubricant was also performed and overall showed the lowest steady-state friction. The wear behavior of the different configurations correlated well with the friction coefficient observations. In addition, ex situ cross-sectional analysis by means of focused ion beam/scanning electron microscopy was performed to capture the third body phenomena and explain the difference in the friction and wear behavior.
Major depressive disorder is the most common neuropsychiatric disorder, affecting 11% of veterans. Here we report results of a large meta-analysis of depression using data from the Million Veteran ...Program, 23andMe, UK Biobank and FinnGen, including individuals of European ancestry (n = 1,154,267; 340,591 cases) and African ancestry (n = 59,600; 25,843 cases). Transcriptome-wide association study analyses revealed significant associations with expression of NEGR1 in the hypothalamus and DRD2 in the nucleus accumbens, among others. We fine-mapped 178 genomic risk loci, and we identified likely pathogenicity in these variants and overlapping gene expression for 17 genes from our transcriptome-wide association study, including TRAF3. Finally, we were able to show substantial replications of our findings in a large independent cohort (n = 1,342,778) provided by 23andMe. This study sheds light on the genetic architecture of depression and provides new insight into the interrelatedness of complex psychiatric traits.
The purpose of this study was to investigate the friction and wear behavior of Co- and Ni-based materials under low and high temperature environmental conditions. The ultimate goal was to identify ...the underlying interfacial processes leading to the observed tribological behavior. Experiments were conducted using a high temperature flat-on-flat fretting apparatus with uncoated pins against a Ni-based counterface. The results showed that the coefficient of friction for this tribocouple decreased with increase in temperature. Similarly, the wear is evidently lower at elevated temperatures compared to the tests performed at lower temperatures. The emphasis of this study was placed on the correlation between the tribological behavior of the Co-based alloy and the third body formation process, characterized using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Ex situ cross-sectional analysis by means of optical microscopy and SEM revealed the formation of transferred oxidized material on the pin. The thickness and composition of the tribofilm varied depending on the sliding condition and correlated well with the friction and wear behavior. This behavior was consistent with the observation from the XPS.
•The friction and wear behavior of Co- and Ni-based materials was investigated under extreme conditions.•Ex situ characterization by means of SEM and XPS revealed importance of third bodies.•Coefficient of friction for this tribocouple decreased with increase in temperature due to oxide-based tribofilm formation.
In response to the novel Coronavirus Disease 2019 (COVID-19) pandemic, the Department of Veterans Affairs (VA) Million Veteran Program (MVP) organized efforts to better understand the impact of ...COVID-19 on Veterans by developing and deploying a self-reported survey.
The MVP COVID-19 Survey was developed to collect COVID-19 specific elements including symptoms, diagnosis, hospitalization, behavioral and psychosocial factors and to augment existing MVP data with longitudinal collection of key domains in physical and mental health. Due to the rapidly evolving nature of the pandemic, a multipronged strategy was implemented to widely disseminate the COVID-19 Survey and capture data using both the online platform and mailings.
We limited the findings of this paper to the initial phase of survey dissemination which began in May 2020. A total of 729,625 eligible MVP Veterans were invited to complete version 1 of the COVID-19 Survey. As of October 31, 2020, 58,159 surveys have been returned. The mean and standard deviation (SD) age of responders was 71 (11) years, 8.6% were female, 8.2% were Black, 5.6% were Hispanic, and 446 (0.8%) self-reported a COVID-19 diagnosis. Over 90% of responders reported wearing masks, practicing social distancing, and frequent hand washing.
The MVP COVID-19 Survey provides a systematic collection of data regarding COVID-19 behaviors among Veterans and represents one of the first large-scale, national surveillance efforts of COVID-19 in the Veteran population. Continued work will examine the overall response to the survey with comparison to available VA health record data.
The predator-prey interactions in the offshore food web of Lake Superior have been well documented, but the sensory systems mediating these interactions remain unknown. The deepwater sculpin, ...(Myoxocephalus thompsoni), siscowet (Salvelinus namaycush siscowet), and kiyi (Coregonus kiyi) inhabit low light level environments. To investigate the potential role of vision in predator-prey interactions, electroretinography was used to determine visual sensitivity for each species. Spectral sensitivity curves revealed peak sensitivity at 525 nm for each species which closely corresponds to the prevalent downwelling light spectrum at depth. To determine if sufficient light was available to mediate predator-prey interactions, visual sensitivity was correlated with the intensity of downwelling light in Lake Superior to construct visual depth profiles for each species. Sufficient daytime irradiance exists for visual interactions to approximately 325 m for siscowet and kiyi and 355 m for the deepwater sculpin during summer months. Under full moon conditions, sufficient irradiance exists to elicit ERG response to light available at approximately 30 m for the siscowet and kiyi and 45 m for the deepwater sculpin. Visual interactions are therefore possible at the depths and times when these organisms overlap in the water column indicating that vision may play a far greater role at depth in deep freshwater lakes than had been previously documented.
While genome wide association studies (GWASs) of Alzheimer's Disease (AD) in European (EUR) ancestry cohorts have identified approximately 83 potentially independent AD risk loci, progress in ...non-European populations has lagged. In this study, data from the Million Veteran Program (MVP), a biobank which includes genetic data from more than 650,000 US Veteran participants, was used to examine dementia genetics in an African descent (AFR) cohort. A GWAS of Alzheimer's disease and related dementias (ADRD), an expanded AD phenotype including dementias such as vascular and non-specific dementia that included 4012 cases and 18,435 controls age 60+ in AFR MVP participants was performed. A proxy dementia GWAS based on survey-reported parental AD or dementia (n = 4385 maternal cases, 2256 paternal cases, and 45,970 controls) was also performed. These two GWASs were meta-analyzed, and then subsequently compared and meta-analyzed with the results from a previous AFR AD GWAS from the Alzheimer's Disease Genetics Consortium (ADGC). A meta-analysis of common variants across the MVP ADRD and proxy GWASs yielded GWAS significant associations in the region of APOE (p = 2.48 × 10
), in ROBO1 (rs11919682, p = 1.63 × 10
), and RNA RP11-340A13.2 (rs148433063, p = 8.56 × 10
). The MVP/ADGC meta-analysis yielded additional significant SNPs near known AD risk genes TREM2 (rs73427293, p = 2.95 × 10
), CD2AP (rs7738720, p = 1.14 × 10
), and ABCA7 (rs73505251, p = 3.26 × 10
), although the peak variants observed in these genes differed from those previously reported in EUR and AFR cohorts. Of the genes in or near suggestive or genome-wide significant associated variants, nine (CDA, SH2D5, DCBLD1, EML6, GOPC, ABCA7, ROS1, TMCO4, and TREM2) were differentially expressed in the brains of AD cases and controls. This represents the largest AFR GWAS of AD and dementia, finding non-APOE GWAS-significant common SNPs associated with dementia. Increasing representation of AFR participants is an important priority in genetic studies and may lead to increased insight into AD pathophysiology and reduce health disparities.
Post-traumatic stress disorder (PTSD) is a major problem among military veterans and civilians alike, yet its pathophysiology remains poorly understood. We performed a genome-wide association study ...and bioinformatic analyses, which included 146,660 European Americans and 19,983 African Americans in the US Million Veteran Program, to identify genetic risk factors relevant to intrusive reexperiencing of trauma, which is the most characteristic symptom cluster of PTSD. In European Americans, eight distinct significant regions were identified. Three regions had values of P < 5 × 10
: CAMKV; chromosome 17 closest to KANSL1, but within a large high linkage disequilibrium region that also includes CRHR1; and TCF4. Associations were enriched with respect to the transcriptomic profiles of striatal medium spiny neurons. No significant associations were observed in the African American cohort of the sample. Results in European Americans were replicated in the UK Biobank data. These results provide new insights into the biology of PTSD in a well-powered genome-wide association study.
We developed an algorithm for identifying U.S. veterans with a history of posttraumatic stress disorder (PTSD), using the Department of Veterans Affairs (VA) electronic medical record (EMR) system. ...This work was motivated by the need to create a valid EMR‐based phenotype to identify thousands of cases and controls for a genome‐wide association study of PTSD in veterans. We used manual chart review (n = 500) as the gold standard. For both the algorithm and chart review, three classifications were possible: likely PTSD, possible PTSD, and likely not PTSD. We used Lasso regression with cross‐validation to select statistically significant predictors of PTSD from the EMR and then generate a predicted probability score of being a PTSD case for every participant in the study population (range: 0–1.00). Comparing the performance of our probabilistic approach (Lasso algorithm) to a rule‐based approach (International Classification of Diseases ICD algorithm), the Lasso algorithm showed modestly higher overall percent agreement with chart review than the ICD algorithm (80% vs. 75%), higher sensitivity (0.95 vs. 0.84), and higher accuracy (AUC = 0.95 vs. 0.90). We applied a 0.7 probability cut‐point to the Lasso results to determine final PTSD case‐control status for the VA population. The final algorithm had a 0.99 sensitivity, 0.99 specificity, 0.95 positive predictive value, and 1.00 negative predictive value for PTSD classification (grouping possible PTSD and likely not PTSD) as determined by chart review. This algorithm may be useful for other research and quality improvement endeavors within the VA.
Resumen
Spanish s by Asociación Chilena de Estrés Traumático (ACET)
Validación de un algoritmo basado en registros médicos electrónicos para identificar el trastorno por estrés postraumático en veteranos de los EE. UU.
VALIDACIÓN DE ALGORITOMO DE TEPT
Desarrollamos un algoritmo para identificar a los veteranos de EE. UU. con historial de trastorno de estrés postraumático (TEPT), utilizando el sistema de registro médico electrónico (RME) del Departamento de Asuntos de Veteranos (AS). Este trabajo fue motivado por la necesidad de crear un fenotipo válido, basado en RME para identificar miles de casos y controles para un estudio de asociación del genoma del TEPT en los veteranos. Utilizamos la revisión manual de tablas (n = 500) como gold estándar. Tanto para el algoritmo como para la revisión de la tabla, fueron posibles tres clasificaciones: PTSD probable, PTSD posible y probablemente no PTSD. Usamos la regresión Lasso con validación cruzada para seleccionar los factores de pronóstico estadísticamente significativos del TEPT a partir de la RME y luego generar una puntuación de probabilidad pronosticada de ser un caso de TEPT para cada participante en la población del estudio (rango: 0–1.00). Comparando el rendimiento de nuestro enfoque probabilístico (algoritmo Lasso) con un enfoque basado en reglas (algoritmo de Clasificación Internacional de Enfermedades CIE), el algoritmo Lasso mostró un porcentaje de acuerdo global modestamente más alto con la revisión de tablas que el algoritmo CIE (80% vs. 75). %), mayor sensibilidad (0.95 frente a 0.84) y mayor precisión (AUC = 0.95 frente a 0.90). Aplicamos un punto de corte de probabilidad de 0.7 a los resultados de Lasso para determinar el estado final de control de caso de TEPT para la población de AV. El algoritmo final tuvo una sensibilidad de 0.99, una especificidad de 0.99, un valor predictivo positivo de 0.95 y un valor predictivo negativo de 1.00 para la clasificación de TEPT (agrupación de TEPT posible y probablemente no TEPT) según lo determinado por la revisión de la tabla. Este algoritmo puede ser útil para otros esfuerzos de investigación y mejora de la calidad dentro del AV.
抽象
Traditional and Simplified Chinese s by the Asian Society for Traumatic Stress Studies (AsianSTSS)
簡體及繁體中文撮要由亞洲創傷心理研究學會翻譯
Validation of an Electronic Medical Record‐Based Algorithm for Identifying Posttraumatic Stress Disorder in U.S. Veterans
Traditional Chinese
標題: 用以找出患創傷後壓力症美國退役軍人的電子健康紀錄為本演算法的效度驗證
撮要: 我們採用美國退伍軍人事務部(VA)電子健康紀錄(EMR)系統, 建立用以找出曾患創傷後壓力症(PTSD)的美國退役軍人的演算法。我們有見針對退役軍人患PTSD的基因組關連研究需有一個有效的EMR為本表型, 以找出數以千計的個案和對照, 因而作此研究。我們以人手進行圖表回顧作為黃金標準 (n = 500)。在演算法和圖表回顧中的分類法都有三種有可能:很大機會患PTSD、有可能患PTSD、 很大機會沒有患PTSD。我們採用Lasso迴歸法並進行交叉驗證, 從EMR選取具統計顯著性的PTSD預測變量, 然後對每個研究樣本作出患PTSD的概率分數預測(值域: 0–1.00)。我們採用的概率分析法(Lasso 演算法) 相比規條為本的分析法 (國際疾病分類 ICD 演算法), 在圖表回顧方面反映稍為較高的整體吻合百分比 (80% vs. 75%), 並有較高敏感度(0.95 vs. 0.84)和準確度(AUC = 0.95 vs. 0.90)。針對Lasso的分析結果, 我們以0.7概率作為取錄點以最後定義VA人口的PTSD個案對照狀態。圖表回顧對於PTSD 分類 (把有可能患 PTSD 及很大機會沒患PTSD結合 ) , 最後的演算法敏感度為 0.99、特殊度 0.99、正向預測值 0.95、負向預測值1.00。此演算法對VA的其他研究和非量化改善計劃可能有所幫助。
Simplified Chinese
标题: 用以找出患创伤后压力症美国退役军人的电子健康纪录为本算法的效度验证
撮要: 我们采用美国退伍军人事务部(VA)电子健康纪录(EMR)系统, 建立用以找出曾患创伤后压力症(PTSD)的美国退役军人的算法。我们有见针对退役军人患PTSD的基因组关连研究需有一个有效的EMR为本表型, 以找出数以千计的个案和对照, 因而作此研究。我们以人手进行图表回顾作为黄金标准 (n = 500)。在算法和图表回顾中的分类法都有三种有可能:很大机会患PTSD、有可能患PTSD、 很大机会没有患PTSD。我们采用Lasso回归法并进行交叉验证, 从EMR选取具统计显著性的PTSD预测变量, 然后对每个研究样本作出患PTSD的概率分数预测(值域: 0–1.00)。我们采用的概率分析法(Lasso 算法) 相比规条为本的分析法 (国际疾病分类 ICD 算法), 在图表回顾方面反映稍为较高的整体吻合百分比 (80% vs. 75%), 并有较高敏感度(0.95 vs. 0.84)和准确度(AUC = 0.95 vs. 0.90)。针对Lasso的分析结果, 我们以0.7概率作为取录点以最后定义VA人口的PTSD个案对照状态。图表回顾对于PTSD 分类 (把有可能患 PTSD 及很大机会没患PTSD结合 ) , 最后的算法敏感度为 0.99、特殊度 0.99、正向预测值 0.95、负向预测值1.00。此算法对VA的其他研究和非量化改善计划可能有所帮助。
ABSTRACT
Introduction
Post‐traumatic stress disorder (PTSD) and traumatic brain injury (TBI) confer risk for Alzheimer's disease and related dementias (ADRD).
Methods
This study from the Million ...Veteran Program (MVP) evaluated the impact of apolipoprotein E (APOE) ε4, PTSD, and TBI on ADRD prevalence in veteran cohorts of European ancestry (EA; n = 11,112 ADRD cases, 170,361 controls) and African ancestry (AA; n = 1443 ADRD cases, 16,191 controls). Additive‐scale interactions were estimated using the relative excess risk due to interaction (RERI) statistic.
Results
PTSD, TBI, and APOE ε4 showed strong main‐effect associations with ADRD. RERI analysis revealed significant additive APOE ε4 interactions with PTSD and TBI in the EA cohort and TBI in the AA cohort. These additive interactions indicate that ADRD prevalence associated with PTSD and TBI increased with the number of inherited APOE ε4 alleles.
Discussion
PTSD and TBI history will be an important part of interpreting the results of ADRD genetic testing and doing accurate ADRD risk assessment.
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