Conservation of energy and momenta in nonholonomic systems with affine constraints

We characterize the conditions for the conservation of the energy and of the components of the momentum maps of lifted actions, and of their `gauge-like' generalizations, in time-independent nonholonomic mechanical systems with affine constraints. These conditions involve geometrical and mechanical properties of the system, and are codified in the so-called reaction-annihilator distribution

Progressive segmented health insurance: Colombian health reform and access to health services

Equal access for poor populations to health services is a comprehensive objective for any health reform. The Colombian health reform addressed this issue through a segmented progressive social health insurance approach. The strategy was to assure universal coverage expanding the population covered through payroll linked insurance, and implementing a subsidized insurance program for the poorest populations, those not affiliated through formal employment. A prospective study was performed to follow-up health service utilization and out-of-pocket expenses using a cohort design. It was representative of four Colombian cities (Cendex Health Services Use and Expenditure Study, 2001). A four part econometric model was applied. The model related medical service utilization and medication with different socioeconomic, geographic, and risk associated variables. Results showed that subsidized health insurance improves health service utilization and reduces the financial burden for the poorest, as compared to those non-insured. Other social health insurance schemes preserved high utilization with variable out-of-pocket expenditures. Family and age conditions have significant effect on medical service utilization. Geographic variables play a significant role in hospital inpatient service utilization. Both, geographic and income variables also have significant impact on out-of-pocket expenses. Projected utilization rates and a simulation favor a dual policy for two-stage income segmented insurance to progress towards the universal insurance goal. Copyright © 2006 John Wiley & Sons, Ltd.