Lower Extremity Musculoskeletal Injury in US Military Academy Cadet Basic Training: A Survival Analysis Evaluating Sex, History of Injury, and Body Mass Index

Background: Injury incidence for physically active populations with a high volume of physical load can exceed 79%. There is little existing research focused on timing of injury and how that timing differs based on certain risk factors. Purpose/Hypothesis: The purpose of this study was to report both the incidence and timing of lower extremity injuries during cadet basic training. We hypothesized that women, those with a history of injury, and those in underweight and obese body mass index (BMI) categories would sustain lower extremity musculoskeletal injury earlier in the training period than men, those without injury history, and those in the normal-weight BMI category. Study Design: Cohort study; Level of evidence, 2. Methods: Cadets from the class of 2022, arriving in 2018, served as the study population. Baseline information on sex and injury history was collected via questionnaire, and BMI was calculated from height and weight taken during week 1 at the United States Military Academy. Categories were underweight (BMI <20), middleweight (20-29.99), and obese (≥30). Injury surveillance was performed over the first 60 days of training via electronic medical record review and monitoring. Kaplan-Meier survival curves were used to estimate group differences in time to the first musculoskeletal injury. Cox proportional hazard regression was used to estimate hazard ratios (HRs). Results: A total of 595 cadets participated. The cohort was 76.8% male, with 29.9% reporting previous injury history and 93.3% having a BMI between 20 and 30. Overall, 16.3% of cadets (12.3% of male cadets and 29.7% of female cadets) experienced an injury during the follow-up period. Women experienced significantly greater incident injury than did men (P <.001). Separation of survival curves comparing the sexes and injury history occurred at weeks 3 and 4, respectively. Hazards for first musculoskeletal injury were significantly greater for women versus men (HR, 2.63; 95% CI, 1.76-3.94) and for those who reported a history of injury versus no injury history (HR, 1.76; 95% CI, 1.18-2.64). No differences were observed between BMI categories. Conclusion: Female cadets and those reporting previous musculoskeletal injury demonstrated a greater hazard of musculoskeletal injury during cadet basic training. This study did not observe an association between BMI and injury

Diving into the vertical dimension of elasmobranch movement ecology

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

Electric Vehicle Modeling Utilizing DC Motor Equations

This paper discusses modeling an electric utility vehicle powered by a separately wound DC motor. Many modeling techniques use steady state efficiency maps and torque-speed curves to describe the performance of electric motors, which can overlook transient response dynamics, current limits, and thermal limits that may affect the end vehicle performance. This paper discusses using bond-graph techniques to develop a causal model of an electric vehicle powered by a separately wound DC motor and development of the appropriate feedforward and feed-back controllers required for route following. The causal model performance is compared to a PSAT model of the same electric vehicle, which uses motor torque-speed curve and efficiency map.Center for Electromechanic

Free software production as critical social practice

This paper analyses the phenomenon of free and open source software (FOSS) in the light of Luc Boltanski and Ève Chiapello's The new spirit of capitalism. It argues that collaborative FOSS production by volunteer software developers is a species of critical social practice in Boltanski and Chiapello's sense: rooted in resistance to capitalist social relations, and yet also a source of values that justify the new routes to profitability associated with contemporary network capitalism. Advanced via collective projects that are sustained by hacker norms and privately legislated ‘copyleft’ law, the FOSS ethos is apparently antithetical to private property-based accumulation. Yet it can be shown to embody the ‘new spirit of capitalism’ in its most distilled form; moreover FOSS developers have instituted new forms of property and new modes of profit creation around software that are in the process of being adapted for use in other economic sectors. Meanwhile, the private law constraints on profit-seeking that have emerged from the FOSS movement are counteracting some of the social pathologies that accompany network capitalism only to consolidate others. The paper concludes by identifying likely bases for a renewal of critique given these realities