Selective laser melting (SLM) is an additive manufacturing process in which multiple, successive layers of metal powders are heated via laser in order to build a part. Modeling of SLM requires ...consideration of both heat transfer and solid mechanics. The present work describes continuum modeling of SLM as envisioned for eventual support of part-scale modeling of this fabrication process to determine end-state information such as residual stresses and distortion. The determination of the evolving temperatures is dependent on the material, the state of the material (powder or solid), the specified heating, and the configuration. Similarly, the current configuration is dependent on the temperatures, the powder-solid state, and the constitutive models. A multi-physics numerical formulation is required to solve such problems. This article describes the problem formulation, numerical method, and constitutive parameters necessary to solve such a problem. Additionally, various verification and example problems are simulated in the parallel, multi-physics finite element code Diablo, and the results presented herein.
In a study involving men with castration-resistant prostate cancer and bone metastases, the alpha emitter radium-223 significantly prolonged survival, as compared with placebo, and was associated ...with fewer adverse events.
More than 90% of patients with metastatic castration-resistant prostate cancer have radiologic evidence of bone metastases, which are a major cause of death, disability, decreased quality of life, and increased treatment cost among these patients.
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,
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Unlike deaths from many other types of cancer, deaths from prostate cancer are often due to bone disease and its complications.
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Current bone-targeted therapies have not been shown to improve survival, and the benefits derived from bisphosphonates, denosumab, and existing radioisotope treatments are primarily limited to pain relief and delay of skeletal events.
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Radium-223 dichloride (radium-223) is a targeted alpha emitter that selectively . . .
A dual pass stabilized mortar contact and mesh tying method is proposed. The method is fully symmetric in that no bias is made when choosing the multiplier space. Using a mesh dependent norm, the ...approach is shown to satisfy an inf–sup stability condition which is used to develop an a-priori error estimator for the bilateral constraint condition. The method was implemented for 3-D and is applicable to contact constraints with normal pressures and tied constraints with surface tractions. The addition of stabilization requires some special attention to show that the inequality constraints are treatable according to the standard KKT conditions. In fact, it is shown that the proposed scheme is equivalent to a particular form of intermediate surface constraint method. The examples compare the standard single surface mortar with the dual pass approach when applicable. Several sensitivity studies of the stabilization parameter are included in the results. A number of examples include nonlinear kinematics, plasticity and self-contact and all performed well for the proposed approach.
•Inf-sup stable, unbiased mortar approach with a-priori error estimate is developed.•Stabilization necessitates analysis showing contact satisfies the KKT condition.•Proposed scheme is shown to have equivalent intermediate surface representation.•Mesh convergence studies demonstrate no locking issues and optimal convergence.•Nonlinear problems are presented along with self-contact problems with buckling.
Summary
Determinants of trabecular bone score (TBS) and vertebral fractures assessed semiquantitatively (SQ1–SQ3) were studied in 496 women with fragility fractures. TBS was associated with age, ...parental hip fracture, alcohol intake and BMD, not SQ1–SQ3 fractures. SQ1–SQ3 fractures were associated with age, prior fractures, and lumbar spine BMD, but not TBS.
Introduction
Trabecular bone score (TBS) and vertebral fractures assessed by semiquantitative method (SQ1–SQ3) seem to reflect different aspects of bone strength. We therefore sought to explore the determinants of and the associations between TBS and SQ1–SQ3 fractures.
Methods
This cross-sectional sub-study of the Norwegian Capture the Fracture Initiative included 496 women aged ≥ 50 years with fragility fractures. All responded to a questionnaire about risk factors for fracture, had bone mineral density (BMD) of femoral neck and/or lumbar spine assessed, TBS calculated, and 423 had SQ1–SQ3 fracture assessed.
Results
Mean (SD) age was 65.6 years (8.6), mean TBS 1.27 (0.10), and 33.3% exhibited SQ1–SQ3 fractures. In multiple variable analysis, higher age (β
per SD
= − 0.26, 95% CI: − 0.36,− 0.15), parental hip fracture (β = − 0.29, 95% CI: − 0.54,− 0.05), and daily alcohol intake (β = − 0.43, 95% CI − 0.79, − 0.08) were associated with lower TBS. Higher BMD of femoral neck (β
per SD
= 0.34, 95% CI 0.25–0.43) and lumbar spine (β
per SD
= 0.40, 95% CI 0.31–0.48) were associated with higher TBS. In multivariable logistic regression analyses, age (OR
per SD
= 1.94, 95% CI 1.51–2.46) and prior fragility fractures (OR = 1.71, 95% CI 1.09–2.71) were positively associated with SQ1–SQ3 fractures, while lumbar spine BMD (OR
per SD
= 0.75 95% CI 0.60–0.95) was negatively associated with SQ1–SQ3 fractures. No association between TBS and SQ1–SQ3 fractures was found.
Conclusion
Since TBS and SQ1–SQ3 fractures were not associated, they may act as independent risk factors, justifying the use of both in post-fracture risk assessment.
Purpose
Machine learning classification algorithms (classifiers) for prediction of treatment response are becoming more popular in radiotherapy literature. General Machine learning literature ...provides evidence in favor of some classifier families (random forest, support vector machine, gradient boosting) in terms of classification performance. The purpose of this study is to compare such classifiers specifically for (chemo)radiotherapy datasets and to estimate their average discriminative performance for radiation treatment outcome prediction.
Methods
We collected 12 datasets (3496 patients) from prior studies on post‐(chemo)radiotherapy toxicity, survival, or tumor control with clinical, dosimetric, or blood biomarker features from multiple institutions and for different tumor sites, that is, (non‐)small‐cell lung cancer, head and neck cancer, and meningioma. Six common classification algorithms with built‐in feature selection (decision tree, random forest, neural network, support vector machine, elastic net logistic regression, LogitBoost) were applied on each dataset using the popular open‐source R package caret. The R code and documentation for the analysis are available online (https://github.com/timodeist/classifier_selection_code). All classifiers were run on each dataset in a 100‐repeated nested fivefold cross‐validation with hyperparameter tuning. Performance metrics (AUC, calibration slope and intercept, accuracy, Cohen's kappa, and Brier score) were computed. We ranked classifiers by AUC to determine which classifier is likely to also perform well in future studies. We simulated the benefit for potential investigators to select a certain classifier for a new dataset based on our study (pre‐selection based on other datasets) or estimating the best classifier for a dataset (set‐specific selection based on information from the new dataset) compared with uninformed classifier selection (random selection).
Results
Random forest (best in 6/12 datasets) and elastic net logistic regression (best in 4/12 datasets) showed the overall best discrimination, but there was no single best classifier across datasets. Both classifiers had a median AUC rank of 2. Preselection and set‐specific selection yielded a significant average AUC improvement of 0.02 and 0.02 over random selection with an average AUC rank improvement of 0.42 and 0.66, respectively.
Conclusion
Random forest and elastic net logistic regression yield higher discriminative performance in (chemo)radiotherapy outcome and toxicity prediction than other studied classifiers. Thus, one of these two classifiers should be the first choice for investigators when building classification models or to benchmark one's own modeling results against. Our results also show that an informed preselection of classifiers based on existing datasets can improve discrimination over random selection.
There are large variations in the incidence, registration methods and reported causes of sudden cardiac arrest/sudden cardiac death (SCA/SCD) in competitive and recreational athletes. A crucial ...question is to which degree these variations are genuine or partly due to methodological incongruities. This paper discusses the uncertainties about available data and provides comprehensive suggestions for standard definitions and a guide for uniform registration parameters of SCA/SCD. The parameters include a definition of what constitutes an 'athlete', incidence calculations, enrolment of cases, the importance of gender, ethnicity and age of the athlete, as well as the type and level of sporting activity. A precise instruction for autopsy practice in the case of a SCD of athletes is given, including the role of molecular samples and evaluation of possible doping. Rational decisions about cardiac preparticipation screening and cardiac safety at sport facilities requires increased data quality concerning incidence, aetiology and management of SCA/SCD in sports. Uniform standard registration of SCA/SCD in athletes and leisure sportsmen would be a first step towards this goal.
Objectives. To identify the prevalence of adverse childhood experiences (ACEs) among sexual or gender minorities (SGMs) and examine the impact of ACEs on their health.
Methods. We analyzed 2021 ...Behavioral Risk Factor Surveillance System (BRFSS) data. Respondents from Arkansas, Iowa, Mississippi, Nevada, and Wisconsin completed modules on 10 individual ACEs, sexual orientation and gender identity, and health.
Results. Among the 38 483 eligible respondents, 2329 (6.1%) identified as an SGM. SGMs reported higher ACE prevalence than did their non-SGM counterparts. ACEs partially attenuated relationships between SGMs and a higher risk for depression, cardiovascular disease, chronic kidney disease, electronic nicotine delivery system use, and cannabis use.
Conclusions. Evaluating and better understanding the ACE and health outcome relationship among SGMs should be prioritized. Targeted interventions are needed to mitigate the impact of ACE-associated sequelae in this population. (Am J Public Health. 2023;113(12):1343–1351. https://doi.org/10.2105/AJPH.2023.307420 )
Summary Background Bone metastases frequently cause skeletal events in patients with metastatic castration-resistant prostate cancer. Radium-223 dichloride (radium-223) selectively targets bone ...metastases with high-energy, short-range α-particles. We assessed the effect of radium-223 compared with placebo in patients with castration-resistant prostate cancer and bone metastases. Methods In this phase 3, double-blind, randomised ALSYMPCA trial, we enrolled patients who had symptomatic castration-resistant prostate cancer with two or more bone metastases and no known visceral metastases, who were receiving best standard of care, and had previously either received or were unsuitable for docetaxel. Patients were stratified by previous docetaxel use, baseline total alkaline phosphatase level, and current bisphosphonate use, then randomly assigned (2:1) to receive either six intravenous injections of radium-223 (50 kBq/kg) or matching placebo; one injection was given every 4 weeks. Randomisation was done with an interactive voice response system, taking into account trial stratification factors. Participants and investigators were masked to treatment assignment. The primary endpoint was overall survival, which has been reported previously. Here we report on time to first symptomatic skeletal event, defined as the use of external beam radiation to relieve bone pain, or occurrence of a new symptomatic pathological fracture (vertebral or non-verterbal), or occurence of spinal cord compression, or tumour-related orthopeadic surgical intervention. All events were required to be clinically apparent and were not assessed by periodic radiological review. Statistical analyses of symptomatic skeletal events were based on the intention-to-treat population. The study has been completed and is registered with ClinicalTrials.gov , number NCT00699751. Findings Between June 12, 2008, and Feb 1, 2011, 921 patients were enrolled, of whom 614 (67%) were randomly assigned to receive radium-223 and 307 (33%) placebo. Symptomatic skeletal events occurred in 202 (33%) of 614 patients in the radium-223 group and 116 (38%) of 307 patients in the placebo group. Time to first symptomatic skeletal event was longer with radium-223 than with placebo (median 15·6 months 95% CI 13·5–18·0 vs 9·8 months 7·3–23·7; hazard ratio HR=0·66, 95% CI 0·52–0·83; p=0·00037). The risks of external beam radiation therapy for bone pain (HR 0·67, 95% CI 0·53–0·85) and spinal cord compression (HR=0·52, 95% CI 0·29–0·93) were reduced with radium-233 compared with placebo. Radium-223 treatment did not seem to significantly reduce the risk of symptomatic pathological bone fracture (HR 0·62, 95% CI 0·35–1·09), or the need for tumour-related orthopaedic surgical intervention (HR 0·72, 95% CI 0·28–1·82). Interpretation Radium-223 should be considered as a treatment option for patients with castration-resistant prostate cancer and symptomatic bone metastases. Funding Algeta and Bayer HealthCare Pharmaceuticals.
Adverse childhood experiences (ACEs) are known determinants of negative health outcomes. Sexual and gender minority (SGM) individuals have higher ACE scores than non-SGM individuals. The SGM-ACE ...scale was developed to better assess this population but is not yet validated in SGM subgroups.
This study aims to validate the sexual and gender minority adverse childhood experiences (SGM-ACE) scale among sexual minority men (SMM) and sexual minority women (SMW), while testing measurement invariance across both groups.
A cross-sectional survey included 530 sexual minority adults (265 men, 265 women) in the United States. Cronbach's alpha established internal consistency reliability. Validity was assessed via confirmatory factor analysis (CFA) for the SGM-ACE's theoretical structure and Pearson's correlations for concurrent validity with substance use outcomes (alcohol, cannabis, and drugs). Multigroup structural equation modeling (SEM) determined measurement invariance between SMM and SMW.
The CFA of the original model exhibited good fit. Fit was improved after removing the institutionalization item, chi-square (
) = 14.26, degrees of freedom (
) = 9,
= 0.113, minimum discrepancy (CMIN/
) = 1.59, comparative fit index (CFI) = 0.99, root mean square error of approximation (RMSEA) = 0.03, 90% confidence interval (CI): (0.00-0.06), and standardized root mean square residual (SRMR) = 0.02. Internal consistency reliability was established (α = 0.78). SGM-ACE exhibited weak, yet significant relationships with each substance use outcome. Multigroup SEM indicated measurement invariance between SMM and SMW.
This study provides psychometric validation of the SGM-ACE, establishing measurement invariance between SMM and SMW. Future research should explore its utility in diverse SGM minority subgroups.
The prevalence of mental health problems among young adults is widely recognized. However, limited research has examined the mental health of Arab American young adults specifically. To address this ...gap in the literature, this study aimed to investigate the effects of multiple stressors including adverse childhood experiences (ACEs), discrimination, and bullying victimization on the mental health of first‐ and second‐generation Arab American young adults. The participants (N = 162) were recruited from a Midwest university using online and in‐person methods. They were screened and completed a demographic questionnaire and self‐report measures of ACEs, discrimination, bullying victimization, and mental health. Hierarchical multiple regression analysis was conducted to examine the effect of psychosocial stressors on mental health and the moderating effect of generation (first vs. second) on that relationship. Female gender, increased perceived discrimination, and more ACEs were associated with lower mental health scores (β = −0.316, p < 0.001, β = −0.308, p < 0.001, and β = −0.230, p = 0.002, respectively). There was a significant negative relationship between victimization and mental health for first‐generation Arab Americans (β = −0.356, p = 0.010). However, that association all but disappeared for second‐generation participants (β = 0.006, p = 0.953). The results highlight the impact of multiple adversities on Arab American young adults' mental health and indicate important nuances related to their generation in the association between bullying victimization and mental health. Implications for practice and future research are discussed.
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