Ensemble diversity was investigated for 12 classifiers and 16 datasets using a generalization error and ambiguity decomposition of the model bias-variance relationship. Diversity was optimized using a genetic algorithm and particle swarm optimization. Classifiers with the greatest contribution to ensemble diversity were learning vector quantization, naïve Bayes classifier, and supervised neural gas, whereas the supervised artificial neural network (SANN) and support vector machines (SVM) classifiers were among the least informative for diversity. An important observation was that classifiers with the greatest optimized employment weights in diverse ensembles also had the greatest association between individual unoptimized diversity, D, and number of classes among datasets, with little association with dataset number of objects or features. The SANN and SVM classifiers had a significant association with the number of objects in datasets and were employed infrequently in diverse ensembles. In conclusion, the diversity of a classifier is more dependent on the number of classes of datasets and less dependent on the number of objects or features. A greater ensemble employment weight for a classifier also occurs when its range of generalization error and ambiguity over all datasets overlap.

A unified approach to regularize maximum likelihood models for linear, multivariate normal, logistic (binomial and polytomous), Poisson, and Cox proportional hazards based on between-predictor correlation is presented. Regularization is accomplished via penalization based on the strength of correlation between variables, using component-wise block boosting of predictors which maximally improve the fit. The advantage of the technique stems from its ability to remove or retain sets of correlated variables as well as overcome the sparseness problem associated with high-dimensional data, which are downfalls of competing regularization methods. Empirical real world datasets are employed with cross-validation (CV).

A noise eigenspace projection method is described to improve accuracy and parsimony for pattern classification. A set of 11 classifiers was employed with 10-fold cross validation on 13 publicly available datasets. For each dataset, a "baseline"' classification analysis was first performed using interclass principal component analysis (PCA) scores based on the signal eigenspace of the correlation matrix. Next, intraclass eigendecomposition was run and percentiles of feature values were projected onto noise eigenvectors from each class to develop an m-tuple of information-to-noise ratio (INR) estimators. The top 5 INR estimators were then used for classification analysis. By projecting percentiles of feature values on the class-specific noise eigenvectors, it was found that INR estimators resulted in a 14 percentage point increase in mean ensemble classifier fusion accuracy over datasets from 84% to 98% when compared with use of signal PCs for class prediction. Unlike feature selection, which identifies features whose values differ greatly across class labels, the proposed approach exploits the fact that the noise eigenspace from all input features differs across classes. We also only used the top 5 INR estimators, which is typically lower than the number of input features selected through filtering or wrapping. Lastly, for operational employment, we recommend use of the k-nearest neighbor (KNN) classifier because of its proximity to ensemble classifier fusion results, high performance, and low computational cost. In conclusion, use of INR estimators based on class-specific noise can greatly improve classification performance and model parsimony without use of input feature selection.

After subarachnoid hemorrhage (SAH), up to 95% of surviving patients suffer from post-SAH syndrome, which includes cognitive deficits with impaired memory, executive functions, and emotional disturbances.Although these long-term cognitive deficits are thought to result from damage to temporomesial–hippocampal areas, the underlying mechanisms remain unknown. To fill this gap in knowledge, we performed a systematic RNA sequencing screen of the hippocampus in a mouse model of SAH. SAH was induced by perforation of the circle of Willis in mice. Four days later, hippocampal RNA was obtained from SAH and control (sham perforation) mice. Next-generation RNA sequencing was used to determine differentially expressed genes in the whole bilateral hippocampi remote from the SAH bleeding site. Functional analyses and clustering tools were used to define molecular pathways. Differential gene expression analysis detected 642 upregulated and 398 downregulated genes (false discovery rate <0.10) in SAH compared to Control group. Functional analyses using IPA suite, Gene Ontology terms, REACTOME pathways, and MsigDB Hallmark gene set collections revealed suppression of oligodendrocytes/myelin related genes, and overexpression of genes related to complement system along with genes associated with innate and adaptive immunity, and extracellular matrix reorganization. Interferon regulatory factors, TGF-β1, and BMP were identified as major orchestrating elements in the hippocampal tissue response. The MEME-Suite identified binding motifs of Krüppel-like factors, zinc finger transcription factors, and interferon regulatory factors as overrepresented DNA promoter motifs. This study provides the first systematic gene and pathway database of the hippocampal response after SAH. Our findings suggest that damage of the entorhinal cortex by subarachnoid blood may remotely trigger specific hippocampal responses, which include suppression of oligodendrocyte function. Identification of these novel pathways may allow for development of new therapeutic approaches for post-SAH cognitive deficits.

BACKGROUND The Vein of Marshall Ethanol for Untreated Persistent AF (VENUS) trial demonstrated that adding vein of Marshall (VOM) ethanol infusion to catheter ablation (CA) improves ablation outcomes in persistent atrial fibrillation (AF). There was significant heterogeneity in the impact of VOM ethanol infusion on rhythm control. OBJECTIVE The purpose of this study was to assess the association between outcomes and (1) achievement of bidirectional perimitral conduction block and (2) procedural volume. METHODS The VENUS trial randomized patients with persistent AF (N = 343) to CA combined with VOM ethanol or CA alone. The primary outcome (freedom from AF or atrial tachycardia [AT] lasting longer than 30 seconds after a single procedure) was analyzed by 2 categories: (1) successful vs no perimitral block and (2) high (>20 patients enrolled) vs low-volume centers. RESULTS In patients with perimitral block, the primary outcome was reached 54.3% after VOM-CA and 37% after CA alone (P = .01). Among patients without perimitral block, freedom from AF/AT was 34.0% after VOM-CA and 37.0% after CA (P = .583). In high-volume centers, the primary outcome was reached in 56.4% after VOM-CA and 40.2% after CA (P = .01). In low-volume centers, freedom from AF/AT was 30.77% after VOM-CA and 32.61% after CA (P = .84). In patients with successful perimitral block from high-volume centers, the primary outcome was reached in 59% after VOM-CA and 39.1% after CA (P = .01). Tests for interaction were significant (P = .002 for perimitral block and P = .04 for center volume). CONCLUSION Adding VOM ethanol infusion to CA has a greater impact on outcomes when associated with perimitral block and performed in high-volume centers. Perimitral block should be part of the VOM procedure.

Interplanetary space radiation presents significant hazards to astronaut health and survival because it can cause both acute and chronic health effects including carcinogenesis. Mitigation of space radiation risks remains critical for enabling human missions beyond Earth orbit. Currently available options for space radiation shielding, such as water shielding, may not be sufficient at reducing space radiation dose and cancer risk to within current regulatory limits. Active magnetic shielding using superconductors has consistently been identified for further study due to its high potential benefit. In response, we have developed Monte Carlo models to determine the effectiveness of several of the latest magnetic shielding concepts, along with current passive shielding techniques, in terms of risk of exposure induced death. This was done for various Mars flyby mission profiles according to current space agency risk tolerance limits. Our study found that few shielding options were able to meet current risk tolerance limits without relying on astronauts of advanced age (>60 years). However, all of the magnetic shielding configurations provided substantial benefit in reducing space radiation cancer risk given high magnetic field strength (7 Tesla). With this information, space agencies can move towards engineering assessments of magnetic shielding technology and begin to advance the concept into a solution enabling interplanetary travel. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.

Background: Few investigations have examined dance-specific injury prevention programs (IPPs), and no published randomized controlled trials are available that evaluate IPPs for dance. Hypothesis: The implementation of an IPP will significantly reduce the risk of injury in professional ballet dancers. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: A randomized controlled trial was designed that entailed a superiority model for the intervention group. All professional dancers from a single ballet company were eligible to participate. Randomization and allocation were performed before the start of the season. The control group practiced and performed without change to preexisting standard operating practice. The IPP group was instructed to perform a 30-minute exercise program 3 times per week over the 52-week study period. Injuries were recorded. Standard continuous and categorical data comparisons and correlations were used. Cox proportional hazards regression models for recurrent failures were used wherein the hazard ratio indicates the relative likelihood of injury in the control versus intervention groups. Results: Of the 52 eligible dancers, 75% (n = 39) participated. Of these 39 dancers, 19 (9 males, 10 females; mean age, 26.6 ± 4.0 years) were randomized to the control group and 20 (11 males, 9 females; mean age, 25.1 ± 5.1 years) to the IPP group. No significant ( P > .05) difference was found in baseline demographics between groups. A total of 116 injuries were recorded for the entire study population (49 IPP; 67 control). Traumatic and chronic injuries accounted for 54% and 46% of injuries, respectively. The injury rate was 82% less (IPP hazard ratio, 0.18; z = –2.29; P = .022) in the IPP group after adjustment for confounding variables, and time between injuries was 45% longer (IPP hazard ratio, 0.55; z = –2.20; P = .028) than for controls. Conclusion: The present study is the first prospective randomized controlled investigation of an IPP for professional ballet. The results showed an 82% decrease in injury rate for the intervention group and an extended period from previous injury to subsequent injury. Registration: NCT04110002 ( ClinicalTrials.gov identifier ).

Background: Inhibition of the main protease 3CLpro of SARS-CoV and SARS-CoV-2 is being targeted in the search for antivirals to shorten patient recovery times from COVID-19 disease. We investigated 72 flavonoids for their potential to bind with the active catalytic site of 3CLpro for SARS-CoV and SARS-CoV-2.Methods: In silico molecular dynamics docking was performed using energy-minimized states of the flavonoids. Three variants of the active catalytic site of the protease 3CLpro were used: one based on x-ray crystallography for SARS-CoV, the second based on x-ray crystallography for SARS-CoV-2, and the third based on a 3D-modelled form of an amino acid sequence alignment of SARS-CoV-2 3CLpro from 8 humans. Docking involved characterization of the best putative pose in the "pocket" of the active site based on altering rotatable bonds in each molecule. The binding energy (kcal/mol) and number of hydrogen bonds were assessed during each pose. Mean binding energy across the 3 variants of 3CLpro was sorted in ascending order to rank each flavonoid, since more negative values indicate stronger binding. Results: The top 10 flavonoids identified were amentoflavone, gallocatechin gallate, diosmin, epigallocatechin gallate, hidrosmin, catechin gallate, elsamitrucin, pectolinaren, quercetin, and isoquercetin. Other flavonoids investigated with significant binding energies were hesperidin, rutin, rhoifolin, and peurarin. Conclusions: Many of the flavonoids identified have been reported in studies of in vitro laboratory-based inhibition of 3CLpro as well as in silico docking studies. Altogether, 14 flavonoids have now been identified in multiple studies: amentoflavone, daidzein, diosmin, epigallocatechin gallate, gallocatechin gallate, herbacetin, hesperidin, luteolin, naringin, peurarin, pectolinarin, quercetin, rhoifolin, and rutin. Existing antiviral clinical trials should consider adding an arm for combined therapy involving antiviral+flavonoid(s), assuming synergistic effects of combined therapy. Group sequential and adaptive human clinical trials should also be rapidly initiated though compassionate use to establish synergistic efficacy for one of more these flavonoids with antivirals. If efficacious synergism is observed, combinations of flavonoids could be consumed by the healthy public for prophylactic protection from SARS-CoV-2 infection providing formularies for dosing and frequency are established. Many of these flavonoids are already available as prescription-free supplements, so they are widely available.

Importance Catheter ablation of persistent atrial fibrillation (AF) has limited success. Procedural strategies beyond pulmonary vein isolation have failed to consistently improve results. The vein of Marshall contains innervation and AF triggers that can be ablated by retrograde ethanol infusion. Objective To determine whether vein of Marshall ethanol infusion could improve ablation results in persistent AF when added to catheter ablation. Design, Setting, and Participants The Vein of Marshall Ethanol for Untreated Persistent AF (VENUS) trial was an investigator-initiated, National Institutes of Health-funded, randomized, single-blinded trial conducted in 12 centers in the United States. Patients (N = 350) with persistent AF referred for first ablation were enrolled from October 2013 through June 2018. Follow-up concluded in June 2019. Interventions Patients were randomly assigned to catheter ablation alone (n = 158) or catheter ablation combined with vein of Marshall ethanol infusion (n = 185) in a 1:1.15 ratio to accommodate for 15% technical vein of Marshall ethanol infusion failures. Main Outcomes and Measures The primary outcome was freedom from AF or atrial tachycardia for longer than 30 seconds after a single procedure, without antiarrhythmic drugs, at both 6 and 12 months. Outcome assessment was blinded to randomization treatment. There were 12 secondary outcomes, including AF burden, freedom from AF after multiple procedures, perimitral block, and others. Results Of the 343 randomized patients (mean [SD] age, 66.5 [9.7] years; 261 men), 316 (92.1%) completed the trial. Vein of Marshall ethanol was successfully delivered in 155 of 185 patients. At 6 and 12 months, the proportion of patients with freedom from AF/atrial tachycardia after a single procedure was 49.2% (91/185) in the catheter ablation combined with vein of Marshall ethanol infusion group compared with 38% (60/158) in the catheter ablation alone group (difference, 11.2% [95% CI, 0.8%-21.7%]; P = .04). Of the 12 secondary outcomes, 9 were not significantly different, but AF burden (zero burden in 78.3% vs 67.9%; difference, 10.4% [95% CI, 2.9%-17.9%]; P = .01), freedom from AF after multiple procedures (65.2% vs 53.8%; difference, 11.4% [95% CI, 0.6%-22.2%]; P = .04), and success achieving perimitral block (80.6% vs 51.3%; difference, 29.3% [95% CI, 19.3%-39.3%]; P < .001) were significantly improved in vein of Marshall-treated patients. Adverse events were similar between groups. Conclusions and Relevance Among patients with persistent AF, addition of vein of Marshall ethanol infusion to catheter ablation, compared with catheter ablation alone, increased the likelihood of remaining free of AF or atrial tachycardia at 6 and 12 months. Further research is needed to assess longer-term efficacy. Trial Registration ClinicalTrials.gov Identifier: NCT01898221.

Background: The association of population mixing (PM1) with childhood acute lymphocytic leukemia (ALL(2)) has been reproduced in multiple studies. However, the mechanism underlying this association is unknown. Methods: Ecological study of incidence of pediatric ALL among 253 counties in the State of Texas (USA) using surrogates of genetic and environmental PM. ALL incidence data were obtained from Texas Cancer Registry and county population statistics from the US Census Bureau. Poisson regression was used to compare ALL incidence and PM. Results: There is substantial and variable genetic and environmental PM among counties in Texas. Indicators of genetic PM including proportion of multiracial households, ratio of Hispanics to non-Hispanics, and ratio of foreign to native-born residents were all significantly associated with a higher incidence of ALL (IRR3 1.81 (95CI 1.05-3.13), 1.67 (95CI 1.16-2.37), and 1.59 (95CI 1.03-2.48), respectively). Surrogates of environmental PM namely population density and persons per household were not associated with incidence of ALL; IRRs 1.29 (95CI 0.4-4.15) and 1.47 (95CI 0.89-2.43). Conclusions: These findings are consistent with prior patterns and magnitudes of PM association with ALL. Our findings suggest that the implicated mechanism of leukemogenesis in PM may be genetically transmitted rather than environmental.

A in silico molecular dynamics (MD) docking investigation was conducted to identify drugs (ligands) which could potentially be of interest for repurposing. We sought ligands which formed the strongest binding potential energy with the x-ray crystallography-based active site of the SARS-CoV-2 protease C3Lpro. A total of 11,013 ligands were obtained from DrugBank. Because of the larger size of the active site of 3CLpro, we chose ligands whose molecular weight (MW) was greater than 400 (daltons) and less than 700, which resulted in 5,920 ligands. After correction of bonds and hydrogens, there were 4,634 ligands available for docking. Docking results indicate that the top 10 investigational and experimental drugs with binding energy (BE)≤-9 kcal/mol were Lorecivivint, Tivantinib, Omipalisib, DrugBank B08450, SRT-2104, R-428, DrugBank B01897, Bictegravir, Ridinilazole, and Itacitinib, while the top 10 approved drugs with BE≤-8.2 were Olaparib, Etoposide, Ouabain, Indinavir, Idelalisib, Trametinib, Lumacaftor, Ergotamine, Canagliflozin, and Edoxaban. There were two antiviral drugs among the top 30 hits, which were Bictegravir (investigational) and Indinavir (approved). The top 10 antivirals with BE≤-8.2 were Bictegravir, Tegobuvir, Filibuvir, Saquinavir, Fostemsavir, Indinavir, Temsavir, Pimodivir, Amenamevir, and Doravirine. Interestingly, the antiviral Remdesavir ranked low among the top 30 antivirals, since its BE was a low value of -7.5 kcal/mol. In silico toxicology and ADME (absorption, distribution, metabolism, excretion) prediction indicates that only 20% (6/30) of the top ligands were “drug-like,” and none were “lead-like,” since the lower bound of MW was 400. Another interesting finding was that the investigational natural supplement Diosmin (DrugBank ID B08995), used without prescription for varicose veins, ranked 22 overall (out of 3,896 with BE≤-6) with a strong BE=-8.8, and formed 8 hydrogen bonds with the active site for the putative best pose. Its energy-minimized 3D structure deeply penetrated and fully covered the width of the active site’s pocket. Diosmin had a lower BE than 97% of the top 30 antiviral drugs and formed more hydrogen bonds with the active site than 93% of the top 30 antivirals. Diosmin could therefore potentially serve as a strong inhibitor of the 3CLpro protease of SARS-CoV-2 and could be investigated in human clinical trials. Since a prescription is not required for its use, it could also be explored as a self-medicating natural alternative to prescribed synthetic drugs. Lastly, the green tea component epigallocatechin gallate (DrugBank ID B12116) also had a low BE=-8.3, and formed 2 hydrogen bonds with the active site, which was a BE that was better than 70% of the top 30 antivirals.

Ischiofemoral impingement (IFI) is a cause of deep gluteal space syndrome. The prevalence of radiographic findings in patients with hip pain is unknown. To assess if there is a correlation between femoral neck-shaft angle (NSA) and the distance of the ischiofemoral space (IFS) and quadratus femoris space (QFS) and to determine the prevalence of quadratus femoris (QF) edema in patients with hip pain. A retrospective case series was conducted involving 100 consecutive hip or pelvis magnetic resonance imaging scans on patients presenting with hip pain. NSA, IFS and QFS distances were measured and presence of QF edema was noted. Analysis of the groups (QF edema vs no edema) was performed using two-tailed t-test and Pearson correlation. There were 18 hips in the edema group (mean age 51.11years +/- 10.5) and 82 hips in the non-edema group (mean age 40.79years +/- 15.9). Within the edema group, there was a moderate positive correlation between NSA and QFS (r=0.498, P=0.036) and a weak positive correlation between NSA and IFI (0.312, P=0.208). The prevalence of QF edema in this study was 18% with only 28% of those subjects having clinical symptoms of IFI. Patients with QF edema had significantly narrower QFS and IFS distances (P<0.001). The prevalence of QF edema is 18% in a consecutive sample of adults with hip pain. In patients with QF edema, only 28% have symptoms of IFI. In patients with QF edema, there was a moderate positive correlation between NSA and QFS.

Background Although pulmonary vein isolation (PVI) is effective in the treatment of paroxysmal atrial fibrillation (AF), its success rates in persistent AF are suboptimal. Ablation strategies to improve outcomes including additional lesions beyond PVI have not consistently shown benefit. Recurrence as perimitral flutter (PMF) is a common form of ablation failure. The vein of Marshall (VOM) contains myocardial connections and abundant sympathetic and parasympathetic innervation implicated in the genesis and maintenance of AF, and is anatomically co-localized with the mitral isthmus, the ablation target of PMF. VOM ethanol infusion is effective in targeting these arrhythmia substrates. Objective To test the safety and efficacy of VOM ethanol infusion when added to PVI in patients undergoing either de novo ablation of persistent AF or after a previous ablation failure. Study design VENUS-AF and MARS-AF are prospective, multicenter, randomized, controlled trials. VENUS-AF will enroll patients undergoing their first catheter ablation of persistent AF. MARS-AF will enroll patients undergoing ablation after previous ablation failure(s). Patients (n = 405) will be randomized to PVI alone or in combination with VOM ethanol infusion. The primary endpoints include procedural safety and freedom from AF or atrial tachycardia (AT) of more than 30 seconds on 30-day continuous event monitors at 6 and 12 months after randomization procedure (single-procedure success), off antiarrhythmic drugs. Key secondary endpoints include AF burden, freedom from AF/AT after repeat procedures and quality of life. Conclusions The VENUS-AF and MARS-AF will determine the safety and potential rhythm control benefit of VOM ethanol infusion when added to PVI in patients with persistent AF undergoing de novo or repeat ablation, respectively.

Natural and synthetic small molecules from the NCI Developmental Therapeutics Program (DTP) were employed in molecular dynamics-based docking with DNA repair proteins whose RNA-Seq based expression was associated with overall cancer survival (OS) after adjustment for the PCNA metagene. The compounds employed were required to elicit a sensitive response (vs. resistance) in more than half of the cell lines tested for each cancer. Methodological approaches included peptide sequence alignments and homology modeling for 3D protein structure determination, ligand preparation, docking, toxicity and ADME prediction. Docking was performed for unique lists of DNA repair proteins which predict OS for AML, cancers of the breast, lung, colon, and ovaries, GBM, melanoma, and renal papillary cancer. Results indicate hundreds of drug-like and lead-like ligands with best-pose binding energies less than -6 kcal/mol. Ligand solubility for the top 20 drug-like hits approached lower bounds, while lipophilicity was acceptable. Most ligands were also blood-brain barrier permeable with high intestinal absorption rates. While the majority of ligands lacked positive prediction for HERG channel blockage and Ames carcinogenicity, there was a considerable variation for predicted fathead minnow, honey bee, and Tetrahymena pyriformis toxicity. The computational results suggest the potential for new targets and mechanisms of repair inhibition and can be directly employed for in vitro and in vivo confirmatory laboratory experiments to identify new targets of therapy for cancer survival.

Purpose: The purpose of this study was (1) to determine the prevalence of burnout in orthopaedic surgeons and (2) to determine whether there is an association or correlation between subject-specific variables (age, attending physician, resident, postgraduate year level, gender, number of calls, total hours worked, and total hours of sleep) and burnout. Methods: Surgeons were prospectively enrolled and provided with a validated wearable device. Subject-specific variables were recorded. Participants completed the Maslach Burnout Inventory and Patient-Reported Outcomes Measurement Information System (PROMIS-29) weekly. Burnout and burnout risk were defined. Multivariate analysis and bivariate correlations were used to determine the association and correlation between subject-specific variables and burnout. Residents were compared to attending surgeons. Results: Of the 26 enrolled subjects, 21 (15 males, 6 females; mean age 37.2 ± 10.9) completed the 4-week study. Residents worked significantly more hours per week than attending surgeons (68.5 ± 15.2 versus 49.9 ± 7.5, P = 0.009). Of the orthopaedic surgeons, 6 (28.6%) experienced burnout, and 7 (33.3%) orthopaedic surgeons were at risk for burnout. There was no significant difference in burnout rates between residents and attending surgeons (P > 0.05). The number of overnight calls was significantly correlated with increased burnout (r = 0.435, P = 0.049). Female gender was significantly associated (P = 0.041) and correlated (r = 0.558, P = 0.009) with burnout. There was no significant association with burnout between the number of hours worked and hours of sleep. Conclusions: The rate of burnout was less than 50% among orthopaedic surgeons. The number of overnight calls and female gender are significantly correlated with increased burnout. There was no significant correlation between hours worked and hours of sleep in surgeon burnout. Clinical Relevance: Burnout is an increasingly common problem among orthopaedic surgeons, and it can have significant negative effects on surgeons’ health and patients’ outcomes. Identifying the predictors of burnout would allow surgeons to address these risk factors and reduce burnout.

We studied the effects of sample size and distribution scale/shape for 3 types of skewness (g1, G1, and b1) and kurtosis (g2, G2, and b2) using 18 simulated probability distributions. In general, skewness and kurtosis always increased with increasing sample size. The order in the skewness coefficients over all distributions and parameters was typically b1, g1, G1. The same pattern was observed for kurtosis, for which order was b2, g2, G2. In terms of a change in sign, mean skewness values (g1, G1, b1) at low sample sizes were unreliable below n=50 for the Beta distribution and unreliable below n=100 for the Student's t and Laplace distributions. Mean kurtosis values for g2 and b2 but not G2 at the smallest samples size were unreliable for most distributions. In fact, b2 was less reliable than g2 for the Laplace, Erlang, exponential, power, and Weibull distributions. Skewness and kurtosis were also dependent on sample size. For skewness G1, the symmetric distributions (normal, Student's t, Laplace, and Logistic) had near-zero mean differences between samples size n=10 and n=100 for each of the scale/shape parameter values used. Whereas the stable, Pareto, and Weibull distributions had the greatest mean differences. Mean differences across sample size for kurtosis G2 within each scale/shape parameter were much greater, and this was also observed among symmetric distributions (Student's t, Laplace, Logistic). The greatest differences of kurtosis G2 across sample size were observed for the Student's t, stable, Pareto, and Weibull distributions. Regarding scale/shape, for skewness G1 the greatest variation was observed for the stable, Weibull, Pareto, and lognormal distributions. While for kurtosis G2, the greatest differences were observed for the Pareto, Weibull, Student's t, and lognormal distributions. The s.d. of skewness cluster analysis shows that the Weibull, and Student's t distributions were unlike any other distributions, since their s.d. decreased drastically with increasing parameter value. Lastly, the lognormal distribution was unlike any other distribution, since its s.d. of skewness greatly increased across increasing parameter values. Students and practitioners should be aware of the types of skewness and kurtosis used in various software packages and their differences. The observed effect of sample size and scale/shape on skewness and kurtosis is also noteworthy and may provide new insights into future research.

To estimate the intra-observer repeatability of shear wave elastography in the UCL of the elbow, and to compare shear wave velocities between dominant and non-dominant arms.

ObjectivesThe purpose of this study was to determine orthopaedic surgery residents' and attending surgeons' resting heart rate (RHR) and heart rate variability (HRV) and if there is a correlation between subject-specific variables (age, attending surgeon, resident, postgraduate year (PGY) level, gender, number of calls, total hours worked, and total hours of sleep) and surgeon RHR and HRV.MethodsOrthopaedic surgery residents and attending surgeons at a single institution were prospectively enrolled and provided a validated wearable device to determine hours of sleep, RHR and HRV. Demographic information, hours worked and overnight calls were recorded. Bivariate correlations were determined using the Spearman rank correlation. Multiple linear regression models were constructed to determine the effect of relevant variables. All p values were reported, and a significance level of α=0.05 was used (p<0.05).ResultsTwenty-one of 26 enrolled subjects completed the 4-week study. The average RHR and HRV for orthopaedic surgeons was 61.8+10.0 bpm and 42.96+21.2ms, respectively. Residents had a significantly higher RHR (66.4+8.4 vs 55.6+8.9, p=0.011) compared with attending surgeons. Overnight calls had the strongest association with decreased HRV (r=−0.447; p=0.038), moderate positive correlation with RHR (r=0.593; p=0.005) and weak negative correlation with HRV (r=−0.469; p=0.032). There was no significant correlation between PGY level, gender, total hours worked and total hours of sleep with RHR or HRV.ConclusionOrthopaedic surgeons have poor RHR and HRV. Additionally, the number of overnight calls had the strongest correlation with worse RHR and HRV.Level of evidenceLevel II; diagnostic, individual cross-sectional study with a consistently applied reference standard.