Infants born preterm and infants born full-term generate more selective leg joint movement during the scaffolded mobile task

Infants born very preterm (PT), prior to 32 weeks gestation, are at increased risk of developing cerebral palsy. Children with spastic cerebral palsy have impaired selective leg joint movement, which contributes to lifelong walking limitations. We investigated whether infants born PT generated more selective hip–knee joint movement (e.g., hip flexes as knee extends) while participating in a scaffolded mobile task. Infants born PT and infants born full-term (FT) at 4 months corrected age participated in a scaffolded mobile task for 2–3 consecutive days. The scaffolded mobile task required infants to raise their legs vertically over a virtual threshold. Three threshold heights (low, middle, and high) were used to test whether the middle and high heights encourage infants to move their legs more selectively. Fifteen infants born FT learned the task and showed more selective hip–knee movement at each of the three threshold heights on the day that they learned, compared with their baseline spontaneous kicking. Thirteen infants born PT learned the task and showed more selective hip–knee movement on their learning day, but only when the middle and high thresholds were used. The results show that the scaffolded mobile task effectively encouraged infants to generate more selective hip–knee joint movement.     

Corporate governance and stakeholder conflict

The stakeholder management literature is dominated by the ‘shareholder value’ and ‘inclusive stakeholder’ views of the corporation. Each views the governance problem in terms of inter-functional conflicts between stakeholder groups, such as between investors and managers or managers and employees, and rests on the assumption of an idealized corporate structure characterized by the separation of ownership from management. Our review of corporate governance and stakeholder conflict shows that such functional-based characterization is too simplistic and fails to account for important intra-functional conflict. Through a comparative review that considers managerial, stakeholder and family systems of governance, we demonstrate that, while the modality of conflict varies by system, substantial intra-functional conflict is endemic to each. We integrate the findings of the agency and comparative stakeholder theories of corporate governance to offer an authority-based framework with three different governance structures that offers complementary insights into stakeholder conflicts. Thus, our study highlights the important, but often neglected, intra-stakeholder type of conflict in various organizations and provides a basis for understanding their various manifestations and consequences under the different systems of governance.     

Job Strain, Workplace Discrimination, and Hypertension Among Older Workers: The Health and Retirement Study

Job strain has been associated with hypertension among younger workers; however, whether this relationship persists among older workers, particularly older racial/ethnic minorities, is unresolved. This study evaluated whether job strain and workplace discrimination are associated with hypertension and poor blood pressure control among older workers and whether these relationships vary by gender and race/ethnicity. Data were drawn from the Health and Retirement Study, and analysis was restricted to employed participants with complete information on job strain and blood pressure (N = 3,794). In adjusted models, high job strain was associated with lower likelihood of hypertension (odds ratio (OR): 0.75, 95% confidence interval (CI): 0.63, 0.89) relative to low job strain. Stratified analyses indicated this association was only significant among white (OR: 0.71, 95% CI: 0.58, 0.86) and male (OR: 0.61, 95% CI: 0.47, 0.79) workers. High job strain was not significantly associated with hypertension among African American (OR: 1.14, 95% CI: 0.63, 2.07) or Hispanic (OR: 0.56, 95% CI: 0.29, 1.09) workers. Workplace discrimination was not associated with hypertension among any group. Neither job strain nor discrimination was associated with poor blood pressure control. These findings suggest that persistence in work characterized by high job strain in later life may signal resilience to the influence of work-related stressors on health. Future research efforts should examine the factors that contribute to gender and racial differences in these relationships.     

Environmental markets in the year 2000

This article examines the prospects for marketable emissions permits in the coming decade. We identify both the reasons that politicians are reluctant to embrace marketable emissions permits as a solution to environmental problems and also changes in the political landscape that could lead to the increased use of this approach. Over the next decade, we believe there is reason to be cautiously optimistic. Selective experimentation with market-based approaches is likely to continue; however, we are not optimistic about the prospects for widespread application of this tool. Moreover, applications of this tool will necessarily reflect important political constraints, thus rendering the tool substantially less effective than the textbook applications examined by economists. An important intellectual challenge is to work on the design of market-based approaches that address political concerns, enhance efficiency, and promote innovation, so that it will be easier to meet the environmental challenges that lie ahead.Mr. Hahn is a Resident Scholar at the American Enterprise Institute and Associate Professor of Economics and Public Policy at Carnegie Mellon University. Mr. Noll is a Professor of Economics at Stanford University. Hahn's research was supported by a grant from the Decision, Risk and Management Science Program at the National Science Foundation. Noll's research is supported by a grant from the Smith-Richardson Foundation. The authors would like to thank Kip Viscusi for helpful comments on an earlier draft.     

Re-examining informative prior elicitation through the lens of Markov chain Monte Carlo methods

Summary.  In recent years, advances in Markov chain Monte Carlo techniques have had a major influence on the practice of Bayesian statistics. An interesting but hitherto largely underexplored corollary of this fact is that Markov chain Monte Carlo techniques make it practical to consider broader classes of informative priors than have been used previously. Conjugate priors, long the workhorse of classic methods for eliciting informative priors, have their roots in a time when modern computational methods were unavailable. In the current environment more attractive alternatives are practicable. A reappraisal of these classic approaches is undertaken, and principles for generating modern elicitation methods are described. A new prior elicitation methodology in accord with these principles is then presented.     

Prenatal Cardiac Function and Postnatal Cognitive Development: An Exploratory Study

Fetal cardiac function was measured at 24, 30, and 36 weeks gestation and quantified in terms of heart rate, variability, and episodic accelerations. Children's representational capacity was evaluated at 27 months in terms of language and play. Thirty‐ and 36‐wcek‐old fetuses that displayed greater heart‐rate variability and more episodic accelerations, and fetuses that exhibited a more precipitous increase in heart‐rate variability and acceleration over gestation achieved higher levels of language competence. Thirty‐six‐week‐old fetuses with higher heart‐rate variability and accelerations, and steeper growth trajectories over gestation, achieved higher levels of symbolic play. Cardiac patterning during gestation may reflect an underlying neural substrate that persists through early childhood: Individual variation in rate of development could be stable, or efficient cardiac function could positively influence the underlying neural substrate to enhance cognitive performance.     

Book reviews

Many Thousands Gone: The First Two Centuries of Slavery in North America. Ira Berlin. Cambridge, MA: Harvard University Press. 1998. x, 497pp. $29.95. ISBN 0–674–81092–9.

More than Chattel: Black Women and Slavery in the Americas. Edited by David Barry Gaspar and Darlene Clark Hine. Bloomington and Indianapolis: Indiana University Press, 1996. xi, 341 pp. £14.99 (paper). ISBN 0–253–21043–7.

From Slavery to Freedom: Comparative Studies in the Rise and Fall of Atlantic Slavery. Seymour drescher. Foreword by Stanley L. Engerman. London: Macmillan. 1999. xxv, 454pp. £55.00. ISBN 0–333–73748–2.

Stylin’: African American Expressive Culture from its Beginnings to the Zoot Suit. Shane White and Graham White. Ithaca and London: Cornell University Press. 1998. xv. 301pp. £23.95 (cloth). ISBN 0–80143179–4.

Raising Cain: Blackface Performance from Jim Crow to Hip Hop. W. T. Lhamon, Jr. Cambridge, MA, and London: Harvard University Press. 1998. 269pp. $25.95 (cloth). ISBN 0–674–74711–9.

Restless Visionaries: The Social Roots of Antebellum Reform in Alabama and Michigan. John W. Quist. Baton Rouge: Louisiana State University Press. 1998. xi, 562pp. £45.90. ISBN 0–8071–2133–9.

Frccdpeople in the Tobacco South: Virginia, 1860–1900. Jeffrey R. Kerr‐Ritchie. Chapel Hill, NC: University of North Carolina press. 1999. xv, 345 pp. $49.95 (cloth); $18.95 (paper). ISBN 0–8078–2460–7; 0–8078–4763–1.

The Freedmen's Bureau and Black Texans. Barry A. Crouch. Austin: University of Texas at Austin Press. 1999. xix, 187pp. $12.95 (paper). ISBN 0–292–71219–7.

Montpelier, Jamaica: A Plantation Community in Slavery and Freedom, 1739–1912. B.W. Higman. Kingston: The Press University of the West Indies. 1998. xv, 384pp. £20.00/$35.00. ISBN 976–640–039–3.

In Place of Slavery: A Social History of British Indian and Javanese Laborers in Suriname. Rosemarijn Hoefte. Gainsville: University of Florida Press. 1998. xii, 275pp. $49.95. ISBN 0–8130–1625–8.

Writing West Indian Histories. B.W. Higman. London and Basingstoke: Macmillan Education. 1999. xiv, 289 pp. £15.50 (paper). ISBN 0–333–73296–0.

Free and Unfree Labour: The Debate Continues. Edited by Tom Brass and Marcel Van Der Linden. Bern/Berlin/Frankfurt a.M: Peter Lang. 1997 (International and Comparative Social History 5). 602 pp. £52.00. ISBN 3–906756–87–4.

Servicing the Master. Slavery and Society in Nineteenth Century Morocco. Mohammed Ennaji. Translated by Seth Graebner. London: Macmillan, 1999. xix, 166pp. £35.00. ISBN 0–333–75477–8.

Servants of Allah. Sylviane A. Diouf. New York: New York University Press. 1998. vii, 254 pp. $18.50. ISBN 0–8147–1905–8     

The longitudinal effects of parental monitoring and self-control on depression in Korean adolescents: A multivariate latent growth approach

The purpose of this study was to examine the longitudinal effects of parental monitoring and self-control on depression. To address this purpose, this study investigated the interrelationships among depression, perceived parental monitoring, and self-control—as well as their developmental changes from the eighth to the twelfth grades—by repeated assessment of 3449 Korean adolescents. The data from Korea Youth Panel Survey (KYPS) of the eighth graders who were followed for five years were analyzed using latent growth modeling. The univariate latent growth models showed that adolescents experience an increase in both parental monitoring and self-control but a decline in depression over the five years. In addition, the multivariate latent growth model suggested that the initial level of parental monitoring had significant effects, both directly and indirectly through self-control, on the initial level of depression. The linear changes in parental monitoring were associated with the linear changes in self-control; likewise, the linear changes in self-control were related to those in depression. These results imply that parental monitoring and self-control need to be emphasized as a strategy in order to prevent or alleviate adolescents' depression.