New Approaches to Final Cooling

A high-energy muon collider scenario requires a "final cooling" system that reduces transverse emittance by a factor of ~10 while allowing longitudinal emittance increase. The baseline approach has low-energy transverse cooling within high-field solenoids, with strong longitudinal heating. This approach and its recent simulation are discussed. Alternative approaches which more explicitly include emittance exchange are also presented. Round-to-flat beam transform, transverse slicing, and longitudinal bunch coalescence are possible components of the alternative approach. A more explicit understanding of solenoidal cooling beam dynamics is introduced.Comment: 6 p

Dangers of Youth Sport Specialization

Year-round training in a single sport is increasingly common among youth athletes. Contributing factors may include external pressures, early recruiting, pursuit of scholarships, and private leagues.Risks may include: overuse injuries, muscle imbalances, degenerative disorders, acute traumatic injuries, and psychological pathologies.This review examined evidence of injury risks associated with early specialization. Evidence from this review can aid educational efforts for athletes, parents, and coaches. Peer-reviewed literature was obtained using the search terms youth sport specialization, injury risks, and psychological effects in SportDiscus, PsycInfo, and Google Scholar, resulting in ­­­­­40 articles reviewed for common themes. Research suggests specializing in one sport during youth development increases risk of short- and long-term injury. Acute injuries may include muscle strains and ligament sprains. Overuse injuries may include apophyseal injuries, osteochondrosis, epiphyseal injuries, muscle imbalance, and ligament or tendon trauma. Research suggests athletes may develop psychological challenges, growth impairments, and physiological imbalances due to early specialization. Athletes, parents, and coaches can benefit from increased education on the adverse effects of early specialization. An increase in overall fitness, coordination, muscle conditioning, healthy bone growth, and psychological health may be achieved by cross training and adequate rest seasons. This may decrease injury predispositions in youth