Robert H. Meyer

Continuous seismic reflection profiling of the deep basement, Hardeman County, Texas

Our understanding of the crust and upper mantle would be enhanced if geophysical studies of the deep basement rocks provided information of resolution and character more nearly like that of geological observations of basement rocks at and near the surface. A test of the continuous seismic reflection profiling technique, the geophysical method with by far the highest resolution and the best potential in this regard, at a site in the midcontinent provided abundant information on intrabasement diffractors and reflectors to depths as great as about 45 km. Conventional equipment and techniques, including nonexplosive vibratory sources, were used with minor modification. In the upper part of the section below the sediments, there are reflectors continuous over the entire length of a profile that give evidence for warping, faulting, unconformities, and other structural features. An age of 1,265 ± 40 m.y. for a sample from a nearby hole indicates that these are Precambrian rocks and not part of the Cambrian basement rocks of the Wichita Province. Detailed correlation with the Precambrian section is inhibited by scarcity of geological information. In the lower part of the section, reflections are not, in general, continuous over more than a few kilometres, but zones and discontinuities within the basement may be distinguished on the basis of spatial density, length, and dip of reflectors. Zones of low reflector density may be plutons; curvature of reflections may indicate deep folded structures. The scale of such features is a few kilometres, and it contrasts with the markedly larger scale of the smallest features of the deep basement that can be resolved by other methods. The method appears to have outstanding potential.

The Effects of the Minimum Wage on the Employment and Earnings of Youth

The employment and earnings effects of the minimum wage are estimated by parameterizing a hypothesized relationship between underlying market employment and wage relationships versus observed wage and employment distributions in the presence of a legislated minimum. If there had been no minimum during the 1973-78 period, we estimate that employment among out-of-school men 16-24 would have been approximately 4% higher than it was. Among young men 16-19 employment would have been about 7% higher; among those 20-24, 2% higher. Employment among black youth 16-24 would have been almost 6% higher than it was, compared with somewhat less than 4% for white youth. Although it is sometimes argued that the adverse employment effects of the minimum are offset by increased earnings, we find virtually no earnings effect. Had the minimum not been raised over the 1973-78 period, inflation would have greatly moderated the adverse employment effects of the minimum, with approximately two-thirds of the potential employment gains from elimination of the minimum attained. The weight of our evidence is inconsistent with a general increase in youth wage rates with increases in the real minimum. Our findings support the hypothesis that the effects of the minimum are concentrated on youth with subminimum market wage rates.

Explaining variation in the effects of welfare-to-work programs.

Evaluations of government-funded training programs often combine results from similar operations in multiple sites. Findings inevitably vary. It is common to relate site-to-site variations in outcomes to variations in program design, participant characteristics, and the local environment. Frequently, such connections are constructed in a narrative synthesis of multisite results. This article uses findings from the evaluations of Californias Greater Avenues for Independence (GAIN) program and the National Evaluation of Welfare-to-Work Strategies (NEWWS) to illustrate why it is important to question the legitimacy of such syntheses. The discussion is carried out using a simple multilevel evaluation model that incorporates models of both individual outcomes within sites and variation in program effects across sites. The results indicate that tempting generalizations about GAIN and NEWWS effects are statistically unjustified but that significant progress might be made in identifying the determinants of program effects in future demonstrations with some changes in evaluation strategy.

Musculoskeletal discomfort, injuries, and tasks accomplished by children and adolescents in Wisconsin fresh market vegetable production

Little or no research is available about the tasks that children and adolescents perform in small scale, fresh market vegetable production. A mail questionnaire was administered in an exploratory study to an age-stratified, convenience sample of children and adolescents age 5 to 18 (n = 81) who were working on Wisconsin fresh market vegetable operations. Children and adolescents reported averaging 349 hours of farm work last year. Youths completed over 1/5 of all the tractor operation and produce loading and unloading that was completed by adults or children on their farms; 1/7 of the weeding, produce washing, and packing; and 1/12 of the hand harvesting during typical weeks when they worked. Fifty percent of 15-18 year olds reported experiencing low back discomfort in the last year, and 25% reported disabling discomfort. Children and adolescents performed the same range of tasks and often the same scope of work as adults. Further investigation with larger, more representative youth samples is needed to confirm these findings.

Use of force plate instrumentation to assess kinetic variables during touch screen use

Touch screens are becoming ubiquitous technology, allowing for enhanced speed and convenience of user interfaces. To date, the majority of touch screen usability studies have focused on timing and accuracy of young, healthy individuals. This information alone may not be sufficient to improve accessibility and usability of touch screens. Kinetic data (e.g. force, impulse, and direction) may provide valuable information regarding human performance during touch screen use. Since kinetic information cannot be measured with a touch screen alone, touch screen-force plate instrumentation, software, and methodology were developed. Individuals with motor control disabilities (Cerebral Palsy and Multiple Sclerosis), as well as gender- and age-matched non-disabled participants, completed a pilot reciprocal tapping task to evaluate the validity of this new instrumentation to quantify touch characteristics. Results indicate that the instrumentation was able to successfully evaluate performance and kinetic characteristics. The kinetic information measured by the new instrumentation provides important insight into touch characteristics which may lead to improved usability and accessibility of touch screens.

Multisite employment and training program evaluations: A tale of three studies

This paper explores the gains from multiplying the number of sites used in experimental evaluation of the effects of employment and training programs. Using a multilevel (hierarchical) statistical framework, the authors analyze the role of site multiplication in three recent program evaluations. Although several experiments have involved substantial numbers of sites, the potential benefits from such strategies are largely unrealized. The authors argue for more involvement of the federal government in designing and implementing evaluations that will allow analysis of how the interaction of client, program, and environmental variables affects outcomes.

Theory and Application of Early Warning Systems for High School and Beyond

This article describes the development of early warning indicators for high school and beyond in the Milwaukee Public Schools (MPS) by the Value-Added Research Center (VARC) at the University of Wisconsin–Madison, working in conjunction with staff from the Division of Research and Evaluation at MPS. Our work in MPS builds on prior early warning work by using both preexisting and new district data sets to build predictive models for identifying students at elevated risk of an entire series of adverse outcomes in high school and beyond, beginning with grade 9 retention and continuing into postsecondary education. This early warning work in MPS makes at least 2 significant contributions to the existing base of research: (a) broadening the set of outcomes that early warning work can predict; and (b) investigating new ways of conveying early warning information to practitioners, such as probability estimates for each outcome and the total quality credits (TQC) measure.

Work exposures, injuries, and musculoskeletal discomfort among children and adolescents in dairy farming.

ABSTRACT Little research is available about the specifics of child or adolescent work on dairy farm operations. The objective of this study was to investigate work performed by children and adolescents on these operations. The authors administered mail questionnaires to a community-based, age- and operation size-stratified sample of individuals aged 6 to 18 (n = 240) who worked on dairy operations in Wisconsin. Data were collected in 1999. The 197 children and adolescents reported averaging 567 hours of dairy farm work in the last year (10.9 hours/week) and completed over 1/3 of all calf feeding, 1/5 of the milking, 1/5 of cow feeding, and 1/10 of tractor operation hours on their farm during the weeks they worked. Some of these young workers reported accomplishing duties also judged by some experts as hazardous work, including nearly half of the 9- to 11-year-olds driving tractors. Six nonfatal injuries were reported that required stopping work (14.6 per 100 full time equivalents per year), including those that required medical attention. Musculoskeletal discomfort and disability reports were unremarkable compared to existing studies of general and working populations. Wisconsin dairy farm youth appeared to be working no more hours per week than their peers in other studies of agricultural populations. Adolescents and some children largely performed the same range of tasks and often the same scope of work as adults, including some performing hazardous work. There is a need for further investigations with larger samples of dairy youth to confirm these findings. The exposures of very young workers to hazardous tractor driving and tower silo tasks suggest that there is an urgent need for improved and validated interventions to reduce these exposures.

Strategies for integrated employment and mental health services.

OBJECTIVE Individual placement and support (IPS) supported employment for people with mental illness is most effective when mental health and employment services are fully integrated within teams in a single agency. Despite this evidence, there are times when separate mental health and employment agencies must collaborate rather than integrate. This article examines how 3 state implementation teams helped separate agencies to partner on IPS supported employment. METHOD The authors used qualitative interviews and direct observations to examine successful collaborations in 3 states. We visited IPS programs on multiple occasions, interviewed multiple stakeholders, and evaluated adherence to the principles of IPS. RESULTS Leaders used 4 strategies to promote successful collaborations: (a) ensuring that employment specialists, and in some cases, vocational rehabilitation counselors, attended mental health treatment team meetings; (b) providing office space for employment staff at the mental health agency; (c) involving supervisors from both agencies in the implementation; and (d) using fidelity reviews to assess the quality of collaboration. CONCLUSIONS AND IMPLICATIONS FOR PRACTICE Practitioners from separate agencies can coordinate services effectively, but successful coordination requires leadership at the state and local levels.

Force and Impulse Production during the Use of a Touch Screen by Individuals with Motor Control Disabilities

People are increasingly required to interact with touch screens at places ranging from grocery stores to airport kiosks. To date, most of the usability research related to touch screens has included young, healthy subjects. Using novel instrumentation consisting of a force plate and a touch screen, a number entry study examined finger-touch screen interaction by participants with Cerebral Palsy, Multiple Sclerosis, and non-disabled controls. Timing data as well as peak forces and impulses in three dimensions were collected for each touch. The results indicate that, although average peak force vector magnitudes, impulses, and dwell times are similar between the groups, there are significant differences within the same three variables by button size. Average peak force vector magnitude increased by 11 percent while the average vector impulse decreased by 29 percent from the smallest to the largest button size. The average dwell time also decreased 23 percent from the smallest to the largest button size.