9 research outputs found
Manifestation of Resonance-Related Chaos in Coupled Josephson Junctions
Chaotic features of systems of coupled Josephson junctions are studied.
Manifestation of chaos in the temporal dependence of the electric charge,
related to a parametric resonance, is demonstrated through the calculation of
the maximal Lyapunov exponent, phase-charge and charge-charge Lissajous
diagrams and correlation functions. The number of junctions in the stack
strongly influences the fine structure in the current voltage characteristics
and a strong proximity effect results from the nonperiodic boundary conditions.
The observed resonance-related chaos exhibits intermittency over a range of
conditions and parameters. General features of the system are analyzed by means
of a linearized equation and the criteria for a breakpoint region with no chaos
are obtained. Such criteria could clarify recent experimental observations of
variations in the power output from intrinsic Josephson junctions in high
temperature superconductors.Comment: 13 pages, 16 figure
The Ambulatory Pediatric Association Fellowship in Pediatric Environmental Health: A 5-Year Assessment
Background: Evidence is mounting that environmental exposures contribute to causation of disease in children. Yet few pediatricians are trained to diagnose, treat, or prevent disease of environmental origin. Objectives: To develop a cadre of future leaders in pediatric environmental health (PEH), the Ambulatory Pediatric Association (APA) launched a new 3-year fellowship in 2001—the world’s first formal training program in PEH. Sites were established at Boston Children’s Hospital, Mount Sinai School of Medicine, George Washington University, University of Cincinnati, and University of Washington. Fellows are trained in epidemiology, biostatistics, toxicology, risk assessment, and preventive medicine. They gain clinical experience in environmental pediatrics and mentored training in clinical research, policy development, and evidence-based advocacy. Thirteen fellows have graduated. Two sites have secured follow-on federal funding to enable them to continue PEH training. Discussion: To assess objectively the program’s success in preparing fellows for leadership careers in PEH, we conducted a mailed survey in 2006 with follow-up in 2007. Conclusions: Fifteen (88%) of 17 fellows and graduates participated; program directors provided information on the remaining two. Nine graduates are pursuing full-time academic careers, and two have leadership positions in governmental and environmental organizations. Ten have published one or more first-authored papers. Seven graduates are principal investigators on federal or foundation grants. The strongest predictors of academic success are remaining affiliated with the fellowship training site and devoting <20% of fellowship time to clinical practice. Conclusion: The APA fellowship program is proving successful in preparing pediatricians for leadership careers in PEH