The Canadian safety net for the elderly.

Recently various analysts have called attention to the apparent success of the Canadian social assistance system in reducing poverty among the elderly and have suggested that there may be lessons to be drawn from the Canadian experience that are relevant to the evolution of the U.S. Supplemental Security Income (SSI) program.

Codons and hypercycles.

Several hypotheses on the origin of codon assignments imply that the present protein synthesizing machinery was already in place when the assignments were made. These are examined by computer modeling. The results do not suggest that assignments were optimized for resistance to reading and mutation errors, nor that the assignments are random.

The issue unresolved: innovating and adapting disability programs for the third era of Social Security.

The history of the Social Security programs in the United States falls into several distinct eras, defined by changing social, demographic, and economic conditions. At present the retirement component of these programs is moving into a stage of program maturation, which poses certain relatively well-understood changes to policymakers. The disability programs are also moving into the same set of societal conditions, but their impact is considerably more difficult to predict.

The challenge of the 21st century: innovating and adapting Social Security systems to economic, social, and demographic changes in the English-speaking Americans.

The Social Security Programs in the United States are complex and have evolved over a long span of years. However, it is possible to categorize much of this experience into two different eras in which Social Security functioned in a distinctive environment, and a third era that is now beginning. The middle third of this century was an "age of invention," in which the programs grew rapidly under favorable social and economic conditions.

The New Beneficiary Data System: the first phase.

The completion of field work for the 1991 New Beneficiary Followup has transformed the 1982 New Beneficiary Survey from a simple cross-sectional data collection effort to the first step in a new longitudinal data base, which is further enriched with information obtained from administrative records. The resulting New Beneficiary Data System will make it possible to develop a better understanding of the dynamics of the experience of aged and disabled populations over the long term. A review of 24 reports prepared by Social Security Administration analysts who have used data from the first wave of interviews reveals a great deal of variation among different types of beneficiaries with respect to income, assets, pensions, work, health, and other factors.