Intention to Act: Predicting Bystander Intervention in Violent Situations in South Korea.

The purpose of this study is to explore the predictors of bystanders' intentions to intervene and types of intended intervention in domestic violence (DV) and sexual violence (SV) situations in South Korea. Using nationally representative data from the 2016 National Fact-Finding Survey on Gender Equality (N = 7,399) and logistic regression-based models, this study focused on two key predictors, bystander gender and attitudes about gender equality, while controlling for age, educational level, and employment status. Our findings indicated that males and females were equally likely to state intentions to intervene in both DV and SV situations. While both males and females were more likely to state that they would intervene indirectly rather than directly, females were even less likely to intervene directly than were males for both situations. Attitudes indicative of gender equality further increased the intention to intervene for DV and SV situations in multivariate models. Gender equality attitudes, however, decreased the intentions to intervene directly in DV but not SV situations. Limitations and implications are discussed.

Suspending loads decreases load stability but may slightly improve body stability.

Here, we seek to determine how compliantly suspended loads could affect the dynamic stability of legged locomotion. We theoretically model the dynamic stability of a human carrying a load using a coupled spring-mass-damper model and an actuated spring-loaded inverted pendulum model, as these models have demonstrated the ability to correctly predict other aspects of locomotion with a load in prior work, such as body forces and energetic cost. We report that minimizing the load suspension natural frequency and damping ratio significantly reduces the stability of the load mass but may slightly improve the body stability of locomotion when compared to a rigidly attached load. These results imply that a highly-compliant load suspension could help stabilize body motion during human, animal, or robot load carriage, but at the cost of a more awkward (less stable) load.

Patient-Reported Outcomes of Periacetabular Osteotomy from the Prospective ANCHOR Cohort Study.

BACKGROUND: Current literature describing the periacetabular osteotomy (PAO) is mostly limited to retrospective case series. Larger, prospective cohort studies are needed to provide better clinical evidence regarding this procedure. The goals of the current study were to (1) report minimum 2-year patient-reported outcomes (pain, hip function, activity, overall health, and quality of life), (2) investigate preoperative clinical and disease characteristics as predictors of clinical outcomes, and (3) report the rate of early failures and reoperations in patients undergoing contemporary PAO surgery. METHODS: A large, prospective, multicenter cohort of PAO procedures was established, and outcomes at a minimum of 2 years were analyzed. A total of 391 hips were included for analysis (79% of the patients were female, and the average patient age was 25.4 years). Patient-reported outcomes, conversion to total hip replacement, reoperations, and major complications were documented. Variables with a p value of ≤0.10 in the univariate linear regressions were included in the multivariate linear regression. The backward stepwise selection method was used to determine the final risk factors of clinical outcomes. RESULTS: Clinical outcome analysis demonstrated major clinically important improvements in pain, function, quality of life, overall health, and activity level. Increasing age and a body mass index status of overweight or obese were predictive of improved results for certain outcome metrics. Male sex and mild acetabular dysplasia were predictive of lesser improvements in certain outcome measures. Three (0.8%) of the hips underwent early conversion to total hip arthroplasty, 12 (3%) required reoperation, and 26 (7%) experienced a major complication. CONCLUSIONS: This large, prospective cohort study demonstrated the clinical success of contemporary PAO surgery for the treatment of symptomatic acetabular dysplasia. Patient and disease characteristics demonstrated predictive value that should be considered in surgical decision-making. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Effects of independently altering body weight and mass on the energetic cost of a human running model.

The mechanisms underlying the metabolic cost of running, and legged locomotion in general, remain to be well understood. Prior experimental studies show that the metabolic cost of human running correlates well with the vertical force generated to support body weight, the mechanical work done, and changes in the effective leg stiffness. Further, previous work shows that the metabolic cost of running decreases with decreasing body weight, increases with increasing body weight and mass, and does not significantly change with changing body mass alone. In the present study, we seek to uncover the basic mechanism underlying this existing experimental data. We find that an actuated spring-mass mechanism representing the effective mechanics of human running provides a mechanistic explanation for the previously reported changes in the metabolic cost of human running if the dimensionless relative leg stiffness (effective stiffness normalized by body weight and leg length) is regulated to be constant. The model presented in this paper provides a mechanical explanation for the changes in metabolic cost due to changing body weight and mass which have been previously measured experimentally and highlights the importance of active leg stiffness regulation during human running.

Dynamics of carrying a load with a handle suspension.

Carrying loads with a compliant pole or backpack suspension can reduce the peak forces of the load acting on the body when the suspension natural frequency is tuned below the stepping frequency. Here we investigate a novel application for a load suspension that could be used to carry a load by hand, which is a common yet difficult method of load carriage and results in inherently asymmetric dynamics during load carriage. We hypothesize that the asymmetric dynamics of carrying a load in one hand will result in multiple locomotion frequency modes which can affect the forces of carrying a load with a handle suspension. We tested an adjustable-stiffness hand-held load suspension with four different natural frequency values while walking and running compared to a rigid handle. As expected, the peak forces acting on the body decrease compared to a rigid handle as the effective suspension stiffness decreases below the stepping frequency. However, the asymmetric dynamics of carrying a load with one hand introduce another frequency mode at half the stepping frequency which increases the peak forces acting on the body when the natural frequency of the handle is tuned near this frequency. We conclude that hand-held load suspensions should be designed to have a natural frequency below the half-stepping frequency of walking to minimize the peak forces and the musculoskeletal stress on the human body while carrying loads with one hand.

Extensive Lower-Extremity Deep Venous Thrombosis Following Arthroscopic Anterior Cruciate Ligament Reconstruction Related to May-Thurner Syndrome: A Case Report.

CASE: An extensive iliofemoral-popliteal deep venous thrombosis following arthroscopic anterior cruciate ligament reconstruction presented on the ninth postoperative day as the result of underlying May-Thurner syndrome. The patient was managed with therapeutic anticoagulation and mechanical disruption of the thrombus. The focal stenosis of the left common iliac vein was addressed with angioplasty and stent placement. Repeat venography demonstrated no residual stenosis of the vein. CONCLUSION: A multidisciplinary approach remains necessary for treating and reducing the risk of post-thrombotic syndrome. The present case further emphasizes the need for aggressive workup and response when a patient presents with left-sided deep venous thrombosis associated with underlying May-Thurner syndrome.

Glenohumeral mismatch affects micromotion of cemented glenoid components in total shoulder arthroplasty.

BACKGROUND: The "rocking horse" phenomenon is considered the main cause of glenoid component loosening by eccentric loading of the glenoid rim. This study aimed to investigate the influence of increasing glenohumeral implant mismatch on bone-implant interface micromotion in a cemented all-polyethylene pegged glenoid biomechanical model. METHODS: Five glenoid sizes, 40 mm, 44 mm, 48 mm, 52 mm, and 56 mm, representing +2 mm, +6 mm, +10 mm, +14 mm, and +18 mm glenohumeral mismatch, respectively, were cyclically loaded according to ASTM Standard F2028-08 at a constant frequency of 2 Hz to a size-dependent humeral head subluxation translation. Additional glenoid components were cyclically loaded to their subluxation translations at a constant humeral head rate of 4.4 mm/s. Component micromotion was characterized as compression, distraction, and superior-inferior translation measured by differential variable reluctance transducers. RESULTS: During constant frequency tests, 52-mm and 56-mm glenoids were unable to complete cyclic testing because of catastrophic failure of the glenoid-implant interface and permanent glenoid deformation, probably due to increasing severity of testing parameters. When tested at a constant humeral head speed, 48-mm, 52-mm, and 56-mm glenoids had significantly increased glenoid distraction and glenoid translation at cycle 50,000 compared with cycle 1. Distraction and translation measurements for 52-mm and 56-mm glenoids were significantly greater compared with 40-mm, 44-mm, and 48-mm glenoids at 50,000 cycles. CONCLUSIONS: In a biomechanical model, optimal glenohumeral mismatch in cemented pegged glenoid implants is multifactorial and has not been definitively established. However, our data suggest that a radial mismatch of less than +10 mm may decrease the risk of glenoid micromotion.

A model of human walking energetics with an elastically-suspended load.

Elastically-suspended loads have been shown to reduce the peak forces acting on the body while walking with a load when the suspension stiffness and damping are minimized. However, it is not well understood how elastically-suspended loads can affect the energetic cost of walking. Prior work shows that elastically suspending a load can yield either an increase or decrease in the energetic cost of human walking, depending primarily on the suspension stiffness, load, and walking speed. It would be useful to have a simple explanation that reconciles apparent differences in existing data. The objective of this paper is to help explain different energetic outcomes found with experimental load suspension backpacks and to systematically investigate the effect of load suspension parameters on the energetic cost of human walking. A simple two-degree-of-freedom model is used to approximate the energetic cost of human walking with a suspended load. The energetic predictions of the model are consistent with existing experimental data and show how the suspension parameters, load mass, and walking speed can affect the energetic cost of walking. In general, the energetic cost of walking with a load is decreased compared to that of a stiffly-attached load when the natural frequency of a load suspension is tuned significantly below the resonant walking frequency. The model also shows that a compliant load suspension is more effective in reducing the energetic cost of walking with low suspension damping, high load mass, and fast walking speed. This simple model could improve our understanding of how elastic load-carrying devices affect the energetic cost of walking with a load.

Ethnic group differences in police notification about intimate partner violence.

We analyzed data from the National Crime Victimization Survey to test whether individuals from different ethnic groups differentially notify the police after incidents of partner violence. After finding that minority groups notified the police about intimate partner violence (IPV) events more than non-minorities, we found that socioeconomic status differences between minorities and non-minorities explained a statistically significant proportion of the reasons underlying the differences in notification. We suggest that the pattern of our results supports a structural perspective and has potential implications about the subjective and objective efficacy of police involvement in IPV.

The relevance of relationship satisfaction and continuation to the gender symmetry debate.

In prior research, Ackerman and Field (2011) found that intimate partner violence (IPV) affects the relationship satisfaction of females more than the relationship satisfaction of males. The current research replicated those findings on a different sample of men and women. In addition to confirming past findings, it also found that gendered patterns in IPV differed substantially for current versus former relationships. Subsequent analyses indicated that gendered differences in whether relationships are continued or terminated after IPV apparently explained these patterns. The current analyses illustrate how relationship continuation differences across gender can produce sample selection biases that substantially affect conclusions about whether partner violence is perpetrated equally by men and women. More specifically, the results of this research are consistent with the conclusion that female IPV victims are more likely than are male victims to become dissatisfied with aggressive opposite-sex partnerships and subsequently terminate their aggressive relationships. For this reason, research that relies only upon the analysis of current relationships will underestimate the amount of partner violence committed by men.