Showing papers by "RAND Corporation published in 1986"

A logic programming framework for planning and simulation

Abstract: A common theme underlying various models that explain information technology adoption is the inclusion of perceptions of an innovation as key independent variables. Although a fairly significant body of research that empirically tests these models is now in existence, some questions with regard to both the antecedents as well as the consequents of perceptions remain unanswered. This paper reports the results of a field study examining adoption of an information technology innovation represented by an expert systems application. Two research objectives that have both theoretical and practical relevance motivated and guided the study. One, the study challenges an assumption which is implicit in technology acceptance models: that of the non-existence of moderating influences on the relationship between perceptions and adoption decisions. Specifically, the study examines the effects of an important moderating influence – personal innovativeness – on this relationship. Two, the study seeks to shed further light on the determinants of perceptions by examining the relative efficacy of mass media and interpersonal communication channels in facilitating perception development. Theoretical and practical implications that follow from the results are discussed.

Voyager 2 in the Uranian System: Imaging Science Results

Abstract: Voyager 2 images of the southern hemisphere of Uranus indicate that submicrometersize haze particles and particles of a methane condensation cloud produce faint patterns in the atmosphere. The alignment of the cloud bands is similar to that of bands on Jupiter and Saturn, but the zonal winds are nearly opposite. At mid-latitudes (-70 degrees to -27 degrees ), where winds were measured, the atmosphere rotates faster than the magnetic field; however, the rotation rate of the atmosphere decreases toward the equator, so that the two probably corotate at about -20 degrees . Voyager images confirm the extremely low albedo of the ring particles. High phase angle images reveal on the order of 10(2) new ringlike features of very low optical depth and relatively high dust abundance interspersed within the main rings, as well as a broad, diffuse, low optical depth ring just inside the main rings system. Nine of the newly discovered small satellites (40 to 165 kilometers in diameter) orbit between the rings and Miranda; the tenth is within the ring system. Two of these small objects may gravitationally confine the e ring. Oberon and Umbriel have heavily cratered surfaces resembling the ancient cratered highlands of Earth's moon, although Umbriel is almost completely covered with uniform dark material, which perhaps indicates some ongoing process. Titania and Ariel show crater populations different from those on Oberon and Umbriel; these were probably generated by collisions with debris confined to their orbits. Titania and Ariel also show many extensional fault systems; Ariel shows strong evidence for the presence of extrusive material. About halfof Miranda's surface is relatively bland, old, cratered terrain. The remainder comprises three large regions of younger terrain, each rectangular to ovoid in plan, that display complex sets of parallel and intersecting scarps and ridges as well as numerous outcrops of bright and dark materials, perhaps suggesting some exotic composition.

Does breastfeeding really save lives, or are apparent benefits due to biases?

Abstract: Analysis of mothers recall data collected in 1976-77 by a probability survey in Peninsular Malaysia shows an association between breastfeeding up to 6 months of age and improved survival of infants throughout the 1st year of life. Inappropriate sample selection and inadequate control of confounding can introduce large biases in these analyses. The magnitude and direction of these biases are presented. Even when these biases are dealt with unsupplemented breastfeeding appears more beneficial than supplemented breastfeeding. The younger the infant and the longer the breastfeeding the greater the estimated benefits in terms of deaths averted. The use of powdered infant formula did not appear to offset the detrimental effects of early weaning and supplementation. The positive relationships found in these analyses between breastfeeding and survival are not due to death precluding or terminating breastfeeding. Nor are they likely to be due to a shift away from breastfeeding because of recent illness which was also controlled in the analyses. Nor are they likely to be due to other factors that both increase mortality risk and shorten breastfeeding; when such factors are taken into account the beneficial effects of breastfeeding become stronger and imply that if there had been no breastfeeding in this sample twice as many babies would have died after the 1st week of life. (authors)

Tracking, Inequality, and the Rhetoric of Reform: Why Schools Don't Change:

Abstract: This paper looks critically at the historical, political, and economic context of differentiated schooling. The argument is made that this context explains the failure to address inequality in the ...

Semiautonomy and Leaving Home in Early Adulthood

Abstract: Studies of leaving home in early adulthood have been inconsistent in whether semiautonomous nonhousehold-based living arrangements such as dormitories barracks and other group quarters are included as "away from home." This study uses data from the National Longitudinal Study of the High School Class of 1972 (NLS72) to trace the living arrangements sequences of young adults to clarify how semiautonomy should best be treated. This study used a 25% random subsample of the entire NLS72 sample of more than 22000. The authors divide living arrangements into 3 categories: 1) residentially dependent 2) semiautonomous and 3) residentially independent. Results show that 1) 21% of males and 18% of females experience residential semiautonomy in their 1st year after high school; 2) in 1973 73% of the young women and 49% of the young men no longer residentially dependent were in semiautonomous living arrangements; 3) in 1973 and 1974 95% or more of those living semiautonomously were either attending school or serving in the military; and 4) by 1979 the few still in semiautonomy were increasingly civilian non-students (35% of males and 85% of females). Treating the semiautonomous as if they had not left home raises the median duration between finishing high school and leaving home by 19 months comapred with treating the semiautonomous as if they had left. Those who were living semiautonomously at the 1st observation were usually more likely to be independent at the later survey than were those who residentially dependent at Time 1 although the effects are often quite small and depend on the type of semiautonomy. 55% of school-leavers and 64% of those ending military service returned home from semiautonomjy between 1973 and 1974. In 1976 52% of former students and 57% of those leaving military service reappeared in the partental home. The authors conclude that studies of leaving home in the US need to consider how semiautonomy is to be treated and such treatment should depend on the type of study being conducted.

Evolving electronic communication networks: an empirical assessment

Abstract: Understanding electronic communication and the patterns that characterize its development are critical to realizing full benefits from computer‐supported work. Cooperative work depends on effective communication and on the ability of organizations to manage the technology of communication appropriately. Organizations that do not understand the political and social dimensions of their communications system will inevitably fail to achieve their purposes.

An Economic Model of Teenage Pregnancy Decision-Making

Abstract: In this paper, we model unmarried teenagers’ decisions about their pregnancy outcome by considering that the teenager contrasts her expected utility (1) as a married mother, (2) as an unmarried mother, or (3) after abortion. We use crosssectional data on 297 California teenagers aged 13-19 who were pregnant for the first time between 1972 and 1974. Both Anglo and Mexican-American girls are included. We find that pregnant girls who are eligible for or are receiving public assistance are more likely to give birth and remain unmarried. Teenagers with greater time values are more likely to choose abortion, and Mexican-American girls are more likely to carry their pregnancies to term.

Response Bias and Reliability in Sensitive Topic Surveys

Abstract: Estimates of survey response bias and reliability are presented for six topics: receipt of welfare, income, alcohol use, drug use, criminal history, and embarrassing medical conditions. The estimates are derived from published full-design criterion validity studies. The common assumption that these characteristics are underreported is, in part, based on partial validity studies; the bias in estimating response parameters using partial designs is demonstrated. Evidence from the full-design studies suggests that the response biases for these topics center near zero but that the responses are unreliable or noisy. Implications for survey design and methodological research are considered.

Expert systems for legal decision making

Abstract: AI technology is being used to develop expert systems that solve complex problems in the legal area. Most of these systems employ rules to describe the strategies and procedures used by litigators to analyze legal issues. The tasks performed by these systems include interpreting the law, anticipating the legal consequences of proposed actions, predicting the effects of changes in legislation, as well as analyzing and managing cases. The special characteristics of the legal domain cause certain problems for expert system builders. We discuss some of these problems and describe LDS and SAL, two expert systems we have developed for case evaluation and settlement in the product liability area. SAL (System for Asbestos Litigation) evolved from the earlier and more general expert system, LDS (Legal Decisionmaking System). We also describe XPL, an explanation facility we developed for use by SAL and other expert system applications.

Object-oriented simulation: where do we go from here?

Abstract: Object-oriented simulation provides a rich and lucid paradigm for building computerized models of real-world phenomena. Its strength lies in its ability to represent objects and their behaviors and interactions in a cogent form that can be designed, evolved and comprehended by domain experts as well as system analysts. It allows encapsulating objects (to hide irrelevant details of their implementation) and viewing the behavior of a model at a meaningful level. It represents special relations among objects (class-subclass hierarchies) and provides “inheritance” of attributes and behaviors along with limited taxonomic inference over these relations. It represents interactions among objects by “messages” sent between them, which provides a natural way of modeling many interactions. Despite these achievements, however, there remain several largely unexplored areas of need, requiring advances in the power and flexibility of modeling, in the representation of knowledge, in the integration of different modeling paradigms, and in the comprehensibility, scalability and reusability of models.The Knowledge-Based Simulation project at Rand is working in several of these areas. In this paper, we will elaborate the existing limitations of object-oriented simulation and discuss some of the ways we believe the paradigm can be extended to surmount these limitations.

Infant mortality decline in malaysia, 1946-1975: the roles of changes in variables and changes in the structure of relationships

Abstract: Individual-level retrospective data from the Malaysian Family Life Survey are used to examine why the infant mortality rate (IMR) has declined rapidly in Malaysia since World War II. Substantial increases in mothers’ education and improvements in water and sanitation have contributed. However, breastfeeding reductions have kept the IMR from declining as rapidly as it would have otherwise. The detrimental effects of reduced breastfeeding more than offset the beneficial effects of water and sanitation improvements. The majority of the IMR decline, however, is not explained by changes in the variables considered here, or in their relationships with infant mortality.

Inductive heating process for use in causing necrosis of neoplasms at selective frequencies

Abstract: A process of effecting necrosis of neoplasms in warm blooded animals as a result of hyperthermia of the neoplasm includes injecting particles into the warm blooded animals in proximity of the neoplasm. The particles are capable of exhibiting hysteresis heating when subjected to an alternating magnetic field. Further, the particles are of a size of at least two microns, or greater, so as to be incapable of being intracellularly absorbed within the cells of either the viable tissue of the animal or the neoplastic tissue. After interjecting the particles in association with the neoplasm, the area of the neoplasm is then subjected to an alternating magnetic field. This field is of a frequency greater than that sufficient to cause any appreciable neuromuscular response to the alternating magnetic field, and is less than that capable of causing any detrimental eddy current heating and/or dielectric heating of viable healthy tissue of the warm blooded animal. The neoplasm is maintained within the field for a time sufficient to heat the particles and the neoplasm, with which the particles are associated, to a temperature of at least 42° C. to cause necrosing of the neoplasm.

Expert systems techniques, tools and applications

Abstract: Expert Systems. Techniques, Tools, and Applications is a collection of research papers covering a range of topics in expert systems and knowledge engineering. The book is edited by Philip Klahr and the late Donald A. Waterman, both of Rand Corporation. The papers are selected from RAND technical reports published from 1977 to 1985. The book is most valuable to people learning knowledge engineering. Four of the papers provide interesting glimpses at the problems involved in transforming knowledge about a domain into computer representations. In addition, the book contains one or two interesting papers for researchers in each of the areas of knowledge acquisition, reasoning with uncertainty, and distributed problem solving.

Agricultural bag loading machine

Abstract: An agricultural bag loading machine having an improved mechanical assembly for automatically effecting controlled, continuous compression and delivery of compacted animal feed material into a flexible agricultural storage bag via a compression and delivery chamber. The compressed, delivered feed material has a uniform, air tight side wall density throughout the bag-delivered, sausage shaped feed material mass. The loading machine has additional features, including a pneumatic bladder assembly for changing the forming chamber dimensions and configuration, an improved agricultural bag attachment and continuous feeding mechanism which eliminates bag fold-over and wrinkling problems during filling, and an integral forming chamber cleanout mechanism which enables clearing and cleaning of the forming chamber at the end of an agricultural bag loading operation.

A numerical code generation facility for REDUCE

Abstract: Many scientific problems require mathematical modeling and symbolic derivation to produce formulas which are evaluated numerically. Computer algebra systems can be used effectively in the symbolic derivation phase and subsequently to generate numerical code. This paper describes the design of the GENTRAN code generation facility for REDUCE.

Dental insurance and the oral health of preschool children

Abstract: Using data from the Rand Health Insurance Experiment, the effects of cost-sharing plans on the health of the primary teeth in 264 children aged 3 to 5 years were investigated. From six areas in the United States, families were assigned at random to different dental and medical insurance plans. The plans varied in the amount of required cost sharing. Families participated in the study for 3 (70%) or 5(30%) years. Children covered by the plan (requiring no cost sharing) had significantly fewer decayed teeth and deft (decayed, extracted, and filled teeth) at the end of the study than did children covered by the cost-sharing plans. No differences existed among plans in the number of extracted and restored teeth. Children of middle- and low-income families benefited most from having access to free dental care.

The Use of Screening in Policy Analysis

Abstract: In most policy analysis studies there are a large number of alternative policies and a large number of impacts to be considered. Time and budget constraints make it impossible to calculate all the impacts for all of the alternatives. As a result, such studies include some process for reducing the number of alternatives to be examined in detail. The process is often implicit and nonscientific e.g., only the decisionmaker's three favorite alternatives are considered. This paper suggests that policy analysis studies explicitly include a screening step, in which the alternatives to be examined in detail and those to be excluded from further consideration are chosen in a scientific and systematic manner. The output from this step is a relatively small set of policy alternatives that are sufficiently attractive that they deserve a more thorough evaluation. Two general screening strategies are described. They are illustrated by describing the screening step in a study to help determine an overall water management policy for the Netherlands.

Enlarging the REDUCE domain of computation

Abstract: We describe the methods available in the current REDUCE system for introducing new mathematical domains, and illustrate these by discussing several new domains that significantly increase the power of the overall system.

The Effects of Parenthood on the Career Orientation and Job Characteristics of Young Adults

Abstract: Scholars of sex differentials in attainment in the labor market have long looked to the effect of the division of labor in the family--especially childbearing and rearing--as 1 of these source differentials. This paper assesses the effects of 1st birth on the career orientation and job characteristics of young adult males and females using data from the National Longitudinal Study of the High School Class of 1972. It examines the hypothesis that those who become parents differ in their views of work even prior to the pregnancy that produces the 1st birth and that parenthood produces changes in career orientation over and above those existing before. The authors also examine the average job characteristics of employed mothers and fathers to assess changes in these around the 1st birth. Results show that mothers differ from nonmothers in several key respects prior to the pregnancy and that the 1st birth results in further changes. For men there is no evidence of initial differences between those who become fathers and those who do not and the authors find effects of parenthood only for general career expectations. (authors modified)

Computer-supported cooperative work: examples and issues in one federal agency

Abstract: The increasing computerization of office work raises a number of questions about the technology's effect on individuals as well as the nature and organization of work. Organizations grapple daily with the realities of implementing advanced information systems, trying to understand how to best exploit the technology in the support of their goals. Such understanding is not trivial given rapid and continuous change in computerbased technologies and their often unpredictable capacity for changing the work of individuals, groups, and even organizations.

1000 ton per day ice plant for underground cooling at Harmony gold mine

Abstract: Up to now all refrigeration plants used for mine cooling have used chilled water. When these refrigeration plants are situated on the surface, large quantities of water must be sent into the mine and pumped back to the surface again. It was suggested that a viable and economic alternative was to make ice on the surface and send this into the mine to reduce the quantity of water required. This Paper describes the world's first very large ice plant used for mine cooling. Ice from this plant is used to cool hot water originating at an underground fissure, and, in addition, provides cooling in the mine.

Mothers' expectations for children's schooling in Malaysia.

Abstract: This article examines a model of mothers' expectations for the eventual educational attainment of their young children in Peninsular Malaysia, a country undergoing rapid development. Focusing on the effects of family characteristics and of key events in young women's lives-education, labor force participation before marriage, and age at family formation-we find that age at first birth affects whether a woman works before marriage but not the type of work she does. Neither the mother's age at first birth nor workprior to marriage have any effect on her expectations for her children's schooling, whereas her own education tends to raise expectations. These findings suggest that mothers attempt to transmit education directly to their offspring through their expectations for their children's schooling.