The rapid evolution of male genitalia is a nearly ubiquitous pattern across sexually reproducing organisms, likely driven by the evolutionary pressures of male-male competition, male-female interactions, and perhaps pleiotropic effects of selection. The penis of many mammalian species contains a baculum, a bone that displays astonishing morphological diversity. The evolution of baculum size and shape does not consistently correlate with any aspects of mating system, hindering our understanding of the evolutionary processes affecting it. One potential explanation for the lack of consistent comparative results is that the baculum is not actually a homologous structure. If the baculum of different groups evolved independently, then the assumption of homology inherent in comparative studies is violated. Here, we specifically test this hypothesis by modeling the presence/absence of bacula of 954 mammalian species across a well-established phylogeny and show that the baculum evolved a minimum of nine times, and was lost a minimum of ten times. Three different forms of bootstrapping show our results are robust to species sampling. Furthermore, groups with a baculum show evidence of higher rates of diversification. Our study offers an explanation for the inconsistent results in the literature, and provides insight into the evolution of this remarkable structure.
Background: Baseball and softball are popular sports in the United States and are responsible for a large number of youth sports injuries each year. Purpose: To investigate recent differences in youth baseball and softball injuries evaluated in nationwide emergency departments. Study Design: Descriptive epidemiology study. Methods: The National Electronic Injury Surveillance System (NEISS) database was examined for softball and baseball injuries in pediatric patients (age, 7-21 years) from 2010 through 2019. Patients were classified as children (age, 7-13 years), adolescents (age, 14-18 years), or young adults (age, 19-21 years). Case narratives were used to categorize injuries as contact injuries (hit by bat or ball), field injuries (sliding into base, collision with another player, catching, or running), throwing injuries, or other. Results: An unweighted total of 24,717 baseball injuries and 13,162 softball injuries were recorded. A nationwide estimate of 861,456 baseball injuries and 511,117 softball injuries were sustained during the studied time period, with estimated respective injury rates of 86,146 and 51,112 per year. Injured softball players were most commonly adolescent (47%) and female (92%), while injured baseball players were most commonly children (54%) and male (90%). There was a greater proportion of baseball-related injuries involving the head/neck (41%) as compared with softball-related injuries (30%) ( P < .01). Conversely, a greater proportion of softball-related injuries involved the lower extremity (32%) as compared with baseball-related injuries (19%) ( P < .01). When comparing diagnosis, softball injuries were more often sprains/strains (28%) than baseball injuries (18%) ( P < .01). When comparing mechanisms of injury, baseball athletes were more likely to be evaluated with contact injuries than were softball athletes (49% vs 40%, P < .01). Conclusion: Youth baseball athletes were more likely to be injured through contact mechanisms and had a higher proportion of injuries related to the head/neck/face, whereas softball injuries more frequently involved the lower extremity and resulted in a sprain/strain. League guidelines should focus on reducing contact injuries within youth baseball, and injury-prevention programs should focus on reducing lower extremity injuries in youth softball.
The importance of emergency obstetric care (EmOC) in reducing maternal mortality has focused attention on both the skills of the clinicians to provide high quality care and on the health facilities in which the care is provided. Essential elements of EmOC include the capacity to perform cesarean sections for which an operating theater is needed. This article focuses on renovation of existing operating theaters to meet the necessary standards. While building, adding to, or renovating operating theaters can be expensive, this article emphasizes appropriate materials that are likely to be locally available and relatively inexpensive. The importance of proper maintenance is discussed.
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