A requirements specification for a software design support system

Most existing software design systems (SDSS) support the use of only a single design methodology. A good SDSS should support a wide variety of design methods and languages including structured design, object-oriented design, and finite state machines. It might seem that a multiparadigm SDSS would be expensive in both time and money to construct. However, it is proposed that instead an extensible SDSS that directly implements only minimal database and graphical facilities be constructed. In particular, it should not directly implement tools to faciliate language definition and analysis. It is believed that such a system could be rapidly developed and put into limited production use, with the experience gained used to refine and evolve the systems over time

An algorithm for generating abstract syntax trees

The notion of an abstract syntax is discussed. An algorithm is presented for automatically deriving an abstract syntax directly from a BNF grammar. The implementation of this algorithm and its application to the grammar for Modula are discussed

Acoustic Tests of a Flexible Spacecraft Model

Acoustic tests of flexible spacecraft mode

The Mystro system: A comprehensive translator toolkit

Mystro is a system that facilities the construction of compilers, assemblers, code generators, query interpretors, and similar programs. It provides features to encourage the use of iterative enhancement. Mystro was developed in response to the needs of NASA Langley Research Center (LaRC) and enjoys a number of advantages over similar systems. There are other programs available that can be used in building translators. These typically build parser tables, usually supply the source of a parser and parts of a lexical analyzer, but provide little or no aid for code generation. In general, only the front end of the compiler is addressed. Mystro, on the other hand, emphasizes tools for both ends of a compiler

Construction of a menu-based system

The development of the user interface to a software code management system is discussed. The user interface was specified using a grammar and implemented using a LR parser generator. This was found to be an effective method for the rapid prototyping of a menu based system

The parser generator as a general purpose tool

The parser generator has proven to be an extremely useful, general purpose tool. It can be used effectively by programmers having only a knowledge of grammars and no training at all in the theory of formal parsing. Some of the application areas for which a table-driven parser can be used include interactive, query languages, menu systems, translators, and programming support tools. Each of these is illustrated by an example grammar

Mothers' and Fathers' Labor Supply in Fragile Families: The Role of Child Health

We estimate the effect of poor child health on the labor supply of mothers and fathers post welfare reform, using a national sample of mostly unwed parents and their children-a group at high risk of living in poverty. We account for the potential endogeneity of child health and find that having a young child in poor health reduces the mother's probability of working, the mother's hours of work, and the father's hours of work. These results suggest that children's health problems may diminish their parents' capacity to invest in their health.

Effects of Child Health on Sources of Public Support

We estimate the effects of having a child in poor health on the mother's receipt of both cash assistance and in-kind public support in the form of food, health care, and shelter. We control for a rich set of covariates, include state fixed effects, and test for the potential endogeneity of child health. Mothers with children in poor health are 5 percentage points (20%) more likely to rely on TANF and 16 percentage points more likely to rely on cash assistance (TANF and/or SSI) than those with healthy children. They are also more likely than those with healthy children to receive Medicaid and housing assistance, but not WIC or food stamps.

Mother's Labor Supply in Fragile Families: The Role of Child Health

A growing body of research indicates that low socioeconomic status in early childhood sets the stage for increasing disadvantages in both health and educational capital over the child's life course and can cause low socioeconomic status to persist for generations. The study estimated the effects of poor child health on the labor supply of mothers with one-year-old children using a national longitudinal data set that oversampled unmarried parents in the post welfare reform era. It was found that having a child in poor health reduces the mother's probability of working by eight percentage points and her hours of work by three per week when she is employed. Another important finding is that the father having children with another partner increases the mothers' labor supply, even after controlling for the focal child's health status and numerous other covariates.

Effects of Child Health on Parents' Relationship Status

We use data from the national longitudinal Fragile Families and Child Wellbeing Study to estimate the effect of poor child health on father presence. We look at whether parents live in the same household 12-18 months after the child's birth and also at how their relationships changed along a continuum (married, cohabiting, romantically involved, friends, or not involved) during the same period. We find that having an infant in poor health reduces the likelihood that parents will live together and increases the likelihood that they will become less committed to their relationship, particularly among parents with low socioeconomic status.