Showing papers by "RAND Corporation published in 1981"

A model of mental health, life events, and social supports applicable to general populations

Abstract: This research addresses measurement issues, derives a model of the effects of life events on mental health, and tests hypotheses regarding the role of social supports in modifying these effects over time. Analyses were based on a longitudinal study of persons (N = 2,234) sampled from a general population in Seattle, Washington, as part of Rands Health Insurance Experiment. In addition to sociodemographic variables, measures of physical limitations, mental health, social supports, and stressful life events were fielded twice (one year apart), using previously validated measures. Data for a random half of the sample were analyzed to evaluate different approaches to defining and scoring life events and social supports and to fit a model of the main and interactive effects of these variables on mental health. The best-fitting model was then crossvalidated, using the remaining half of the sample. Results support the following conclusions: (1) Social supports predict improvements in mental health over time, (2) life events and physical limitations predict a deterioration in mental health over time, (3) the negative effects of life events and physical limitations on mental health do not vary according to amount of social support, and (4) differences in measurement strategies for life events and social supports produce some variance in results, but not in conclusions about whether effects on mental health are additive or interactive. This paper presents a longitudinal analysis

Repeat migration, information costs, and location-specific capital

Abstract: It is well-known from previous research that recent migrants often migrate again This paper seeks to illuminate several possible mechanisms that might give rise to this association The effect of previous migration on subsequent migration appears to be largely due to the fact that the consequences of one move often become the cause of the next and that people tend to return to places they recently left The concepts of location-specific capital (assets that are more valuable in their current location than they would be elsewhere) and information costs provide powerful explanations for the patterns of multiple movement disclosed in the longitudinal data used in this study

Return and other sequences of migration in the United States

Abstract: We examine repeat migration sequences in the United States especially those that entail a return, using data from the Panel Study of Income Dynamics. Our guiding hypotheses derive from the concepts of location-specific capital and imperfect information. Descriptive analysis elucidates the dynamics, tempo, and differential frequency of repeat migration among various socioeconomic groups. Results disclose differences among migrants who choose to return or move onward to a new location, or do not move again, and lend support to our analytical framework. Major findings are: (1) the propensity to return to an area varies directly with the amount of locationspecific capital that is left behind and inversely with the ex-resident’s length of absence, (2) which repeat migration sequence unfolds—return or onward—depends on the ex-resident’s educational level and experience of unemployment.

Spatial learning and reasoning skill

Abstract: People’s everyday activities frequently depend on the skilled performance of spatial tasks in large-scale environments. Such tasks include learning an unfamiliar region through navigation or from a map, estimating distances between locations along a route or as the crow flies, estimating the bearing of an unseen location from a current position, and reading and interpreting a map. Individuals vary widely in their skill at performing these tasks (Farrell & Potash, 1979; Kozlowski & Bryant, 1977; McGee, 1979; Simutus & Barsam, this volume). In our research, we have been investigating the psychological bases of spatial skills. We undertook this research to provide a theoretical foundation for understanding and improving human performance on spatial tasks. We assume that successful performance on spatial tasks depends on both task demands (e.g., requisite knowledge, alternative possible solution paths) and the cognitive resources available to the individual (e.g., memory capacity, solution strategies, ability to perform solution operations). Thus, remediation efforts can focus either on providing the individual with additional cognitive resources (e.g., by teaching effective strategies) or by altering the task to fit existing human capabilities (e.g., by providing additional sources of information).

Young women's transition to marriage.

Abstract: This paper examines determinants of timing of marriage for young women by modeling the transition from the single to the married state by age. This approach, combined with a large longitudinal data set, allows us to disaggregate the analysis into fine age groupings and to include situational and attitudinal factors in our model. We find that those characteristics of a young woman's parental family that reflect the availability of parental resources tend to decrease the chances of a marriage during the early teens. Chances of marrying appear to decrease with increases in the availability and attractiveness of alternatives to the wife role and in the costs of assuming it. We discuss these results from the perspective of the societal and parental normative pressures which affect timing of marriage for young women.

Short- and long-term residents of nursing homes.

Abstract: This article analyzes reported data on length of stay of discharged patients from the 1977 National Nursing Home Survey. Assuming that patients admitted to nursing homes are one of two types, short-stayers and long-stayers, the statistically best-fitting proportions and expected lengths of stay for the two types are derived. The results are applied to statistics on characteristics of resident and discharged patients to find admission characteristics that differentiate the two groups. Because long-stayers and short-stayers have quite different characteristics, nursing home statistics will be very different if one bases them on discharges or a cross-section of residents. For example, we estimate that short-stay patients represent 61 per cent of discharges but only 9 per cent of residents. A further application shows that, including deaths in hospitals, almost half of discharged patients die, rather than the usually cited figure of 25 per cent.

Clinical Science: Normal TMJ Bony Relationships in Centric Occlusion

Abstract: In a preliminary investigation, condyle-temporal bone spatial relationships were determined quantitatively in 50 asymptomatic TMJs (25 subjects) by making area measurements of the posterior and anterior portions of the joint spaces. For both right and left sides, the numerical expression of the joint relationship indicated that the condyle is normally centered in the joint to a very high degree. Standard deviations around the mean joint relationship values were large, however, which suggests that the posteroanterior variation of condyle positions in asymptomatic TMJs is greater than commonly thought. In addition, there was only mild correlation between individual joint relationships on right and left sides.

Improved care for patients on a new geriatric evaluation unit.

Abstract: An analysis is presented of a geriatric evaluation unit (GEU) established at the Sepulveda VA Medical Center in 1979 to provide comprehensive interdisciplinary assessment and treatment of geriatric inpatients. The data on 74 patients admitted during the first year show that major improvements can occur in several outcome areas. Placement location was improved over expectations in 48.4 percent of patients, thus permitting a higher level of independence with a lower level of care requirements. Functional status (Katz ADL scale) improved in two-thirds of the patients who could have shown improvement. An average of almost four new treatable disorders not noted by previous physicians were diagnosed per patient. The mean daily number of prescribed drugs was reduced by 32 percent per patient, and the total number of drug doses by 43 percent. Though limited by the unique aspects of the vA situation and by lack of a control group, the findings lend support to the efficacy and value of the GEU concept. (A randomized controlled study is in progress.)

Coordinates of features on the Galilean satellites

Abstract: The coordinate systems of each of the Galilean satellites are defined and coordinates of features seen in the Voyager pictures of these satellites are presented. The control nets of the satellites were computed by means of single block analytical triangulations. The normal equations were solved by the conjugate iterative method which is convenient and which converges rapidly as the initial estimates of the parameters are very good.

AUTOPILOT: a distributed planner for air fleet control

Abstract: Distributed planning requires both architectures for structuring multiple planners and techniques for planning, communication, and cooperation. We describe a family of systems for distributed control of multiple aircraft, in which each aircraft plans its own flight path and avoids collisions with other aircraft. AUTOPILOT, the kernel planner used by each aircraft, comprises several processing "experts" that share a common world model. These experts sense the world, plan and evaluate flight paths, communicate with other aircraft, and control plan execution. We discuss four architectures for the distribution of airspace management and planning responsibility among the several aircraft occupying the airspace at any point in time. The architectures differ in the extent of cooperation and communication among aircraft.

Amalthea: Voyager imaging results

Abstract: Voyager images of Amalthea are presented, which reveal an irregular satellite in synchronous rotation relative to Jupiter with dimensions of 270 x 165 x 150 km. The surface appears scarred by large craters and sharp ridges to indicate a history of cosmic battering. Amalthea'a normal surface reflectance is 5-6% with a very red color and a mean opposition angle magnitude of +14. The phase coefficient between phase angles of 0.8 and 42 deg of 0.042 + or - 0.004 mag/deg indicates that the phase integral does not exceed 0.3 and the Bond Albedo is less than 0.02. Several prominent bright spots of 10-50 km across occur on local slopes and ridges, have albedos several times higher than the background, and have a greenish color where the spectrum bends down beyond 0.56 microns.

Making desegregation work: Extracurricular activities

Abstract: Southern desegregated high schools with high levels of black or white student extracurricular participation have students who report more interracial contact, higher self-esteem, more positive attitudes toward school, more parent visits to schools, and more personal contact with teachers. The results are derived from regression equations based on responses from 10,000 students in 200 schools, controlling on student and school background factors. The author recommends that secondary schools place high priority on encouraging extracurricular participation and argues that this enhances the school's ability to teach because it increases student attachment to the school, reduces student alienation, provides alternative channels for students to develop self-esteem, and increases the opportunity for positive interracial contact.

Dynamic subchannel allocation

Abstract: An apparatus for and a method of Dynamic Subchannel Allocation permitting easily field modifiable assignment of Input/Output (I/O) subchannels to I/O channels. Many present day medium-to-large scale computers have an I/O unit(s) with a fixed number of I/O ports or I/O channels for the transmission of information between the computer and peripheral devices. Improvements to these I/O channels, now common in the art, permit multiple peripheral devices to be coupled to the computer through a single I/O channel. Each of these multiple peripheral devices may be said to communicate through an I/O subchannel. A given I/O subchannel designation logically specifies the hardware within the shared I/O channel that is dedicated to communication with the corresponding one of the multiple peripheral devices coupled to that shared I/O channel. The present invention is an improvement which provides for allocation of I/O subchannels to I/O channels in the field rather than at time of manufacture. A random access memory (RAM) is employed which provides the correlation between each I/O subchannel and the I/O channel to which it has been allocated. The RAM is called the Channel Descriptor Stack (CDS). The CDS may be loaded using a variety of techniques. In the preferred embodiment, the CDS is loaded via a specialized processor, called a system support processor (SSP), which also performs those tasks normally associated with system control (e.g., system reconfiguration, interface to the system operator, casualty recovery, etc.).

Multiple Three-Decision Rules for Factorial Simple Effects: Bonferroni Wins Again!

Abstract: Multiple t tests are used to decide which of several simple effects are positive and which are negative. Exact critical points are derived and compared with simple conservative bounds of Bonferroni, Scheffe, and Tukey, with the Bonferroni bounds being close and relatively closest to the exact values.

An object-oriented language for constructing simulations

Abstract: Simulation represents a powerful tool for reasoning about possible worlds, and, more generally, can be regarded as an important design aid. The design of physical systems is often accomplished by a cycle of activities, including phases that construct models, test the model's behavioral consequences by simulation, diagnose the causes for poor behavior in terms of design weaknesses, and propose model changes. In this paper we present an overview of ROSS, a domain-independent language for writing simulations in a wide variety of domains. ROSS has two distinct components. First ROSS embeds a kernel that is sufficiently powerful to create procedural models of complex systems. Second, ROSS includes important tools that assist the user at several other stages of the design cycle; specifically, in diagnosing system performance problems, and in proposing intelligent model changes. We show specific examples of how ROSS's meta-description capabilities enable it to provide a friendly design environment.

Consumer reactions to the tone of written drug information

Abstract: Emotional and cognitive reactions to four different patient package inserts (PPIs) describing flurazepam were tested. All documents contained the same basic information. However, this information was presented in a frank manner to half the subjects and in a reassuring manner to the other half. In addition, in both cases, drug side effects were presented either as a list or in paragraph form. Study subjects--456 members of a college community--each read one of the PPIs and then completed a self-administered questionnaire that had 10 multiple-choice questions about flurazepam and 19 scaled questions focusing on semantics. The frank version was judged clearer, more interesting, longer, and more appropriate for an adult audience. Tone also affected which items of information in the PPI were remembered best, possibly because it helped to establish which information was considered most important. Caution should be observed in generalizing the study conclusions until they are corroborated by research on a wider patient population.

A guide through the maze of long-term care.

Abstract: Complicated requirements regarding eligibility and coverage as well as variations in the availability of programs confuse even the most diligent physicians trying to advise elderly patients about health care services. Nevertheless, awareness of such government and community resources is critical because physicians play an essential role in assisting the elderly to receive maximum health care benefits, particularly during long-term illness.

Vented compressor inlet guide

Abstract: To provide reduction in temporary conditions of excess load on the thrust bearing, a labyrinth positioned contiguous to a leakage aperture in the high pressure side of a single stage overhung compressor rotor affords controlled leakage to a venting circuit in communication with a lower pressure system. A pressure switch responsive to pressure levels in the venting circuit prevents compressor start at pressures above the set point of the switch while a backpressure valve in the venting circuit when operative maintains a predetermined pressure level therein. When the thrust bearing is operating at speeds sufficient to enable acceptance of the load imposed by compressor pressure, an override solenoid valve serves to close the backpressure valve and operably shut the venting circuit.

The applications of artificial intelligence to law: a survey of six current projects

Abstract: The literature on computer-based consultation systems has often suggested the possibility of building an expert system in the field of law, but it is only recently that several researchers have begun to explore this possibility seriously. For this session, we have assembled summaries of six major projects on the applications of artificial intelligence to legal problem domains, and we have invited representatives of these six projects to participate in a panel discussion of their work.

Friction rock stabilizer and a method of isolating the same from a bore surface

Abstract: The friction rock stabilizer comprises an elongate element for insertion into an earth structure bore, for stabilizing the earth structure, which has a sheath rendering the stabilizer impervious to chemical attack and, hence, corrosion-resistant. The bore surface isolating method, in an embodiment thereof, comprises interposing a protective or isolating sleeve or lining between the stabilizer and the earth structure bore. The protective or isolating lining provides two benefits: it facilitates movement of the stabilizer into frictional engagement with the bore, by isolating the stabilizer from the rough surface of the bore wall, and also provides a corrosion-resistant sheath to protect the stabilizer, in the bore, from alkaline or acidic mine water, corrosive minerals, and the like.