Showing papers by "Hampshire College published in 1990"

Assessment of systemic physiological perturbations from dental enamel hypoplasias and associated histological structures

Abstract: Dental enamel hypoplasias are deficiencies in enamel thickness resulting from physiological perturbations (stress) during the secretory phase of amelogenesis. The results of a wide variety of experimental, clinical, and epidemiological studies strongly suggest that these defects and their associated histological abnormalities (such as accentuated stria of Retzius and Wilson bands) are relatively sensitive and nonspecific indicators of stress. Because of the inability of enamel to remodel, and the regular and ring-like nature of their development, these defects can provide an indelible, chronological record of stress during tooth crown formation. For these reasons, along with the ease with which they are studied, enamel hypoplasias have been increasingly employed as indicators of nutritional and disease status in paleopathology, and their study has begun to extend into other subdisciplines of physical anthropology. In order to provide the reader with a better understanding of the current issues in this field, we first review normal enamel development, historical advances in the study of enamel developmental abnormalities, and provide a threshold model to help conceptualize the etiology of enamel developmental defects. Specific attention is then centered on extant, fundamental issues in the use of enamel hypoplasias and histological structures as epidemiological indicators of nonspecific stress. Most enamel hypoplasias are associated with abnormal histological changes (accentuated stria of Retzius or “Wilson” and “Cluster” bands). However, the lack of association of some mild surface irregularities, characteristically seen as thin, perikymata-like surface depressions, with abnormal prism morphology suggests that these surface features may not be evidence of physiological perturbation. Methods now exist to reliably identify both histological and enamel surface defects. However, further research is needed on methods for determining the size of defects and the epidemiological significance of defect widths and depths. Similarly, the general relationship between the location of enamel hypoplasias and associated histological structures on the one hand, and an individual's age at the time of their development on the other hand, is also well understood. However, better estimates of intra- and inter-population variation in the timing of enamel matrix formation are needed before these defects can reach their full potential as chronometric measures of stresses. Lack of understanding patterns of differential susceptibility of enamekl to developmental disruption has likely hindered interpretations of the results of a number of past experiments. The seemingly strong pattern of differential suscetibility of enamel to disruption-within teeth and across tooth classes, dentitions, and taxa-may yield a number of significant clues to understanding basic issues in enamel development. Populations that are exposed to a high degree of undernutrition and disease, from prehistoric to contemporary times, share high rates of linear enamel hypoplasias. While these defects seem to relate to bouts of undernutrition and infection, their specific etiology is still unknown. In the next decade we expect to develop more precise information on the specificity and sensitivity of secretory ameloblaste to disruption. A variety of research directions are suggested for further anthropological study.

Fifties Television: The Industry and Its Critics

Abstract: Just a few years in the mid-1950s separated the "golden age" of television's live anthology drama from Newton Minow's famous "vast wasteland" pronouncement. Fifties Television shows how the significant programming changes of the period cannot be attributed simply to shifting public tastes or the exhaustion of particular program genres, but underscore fundamental changes in the way prime-time entertainment programs were produced, sponsored, and scheduled. These changes helped shape television as we know it today. William Boddy provides a wide-ranging and rigorous analysis of the fledgling American television industry during the period of its greatest economic growth, programming changes, and critical controversy. He carefully traces the development of the medium from the experimental era of the 1920s and 1930s through the regulatory battles of the 1940s and the network programming wars of the 1950s.

Use of Detrital Foods and Assimilation of Nitrogen by Coastal Detritivores

Abstract: Two killifish common in east coast U.S.A. salt marshes,Cyprinodon variegatus Lacepede andFundulus heteroclitus Walbaum, differ in their ability to assimilate nitrogen from and grow on detritus.C. variegatus grew on a diet of detritus ofSpartina alterniflora Loisel, whileF. heteroclitus did not. In addition, when the fish were fed15N-labeledS. alterniflora detritus,15N:14N ratios inC. variegatus were higher than were ratios inF. heteroclitus. Therefore, even though both species ingest large amounts of detritus,C. variegatus makes more effective use of this portion of its diet. These dietary differences are corroborated by anatomical differences that suggest thatC. variegatus should make better use of detrital or plant tissues thanF. heteroclitus. In the label experiment, the degree of label in both fish was directly proportional to the degree of label in the food treatments. In previously published experiments designed to compare plant substrate with attached microbes as nitrogen sources for detritivores, %15N incorporated by a polychaete was also directly proportional to %15N in the detrital food. Therefore, it is difficult to distinguish between plant substrate and microbes as nitrogen sources for this detritivore.

Harvest of sustainability: Recent books on environmental management

Abstract: Sustainable Environmental Management. Edited by Kerry Turner. London: Pinter, 1988. Pp.ix + 292. £27.50. ISBN 1 85293 003 9. The Theory of Environmental Policy. 2nd ed. By William Baumol and Wallace Oates. Cambridge: Cambridge University Press, 1988. Pp.x+ 299. £35. ISBN 0 521 32224 3. Deforestation: Social Dynamics in Watersheds and Mountain Ecosystems. Edited by J. Ives and D. Pitt. London: Routledge, 1988. Pp.xiii + 247. £35. ISBN 0 415 00456 X Elevage et developpement au Niger. By Brigitte Thebaud. Geneva: ILO, 1988. Pp.xiv + 147. SFr 15. ISBN 92 2 205605 1. Primary Resources and Energy in the Third World. By John Soussan. London: Routledge, 1988. Pp.vi + 114. £5.95. ISBN 0 415 00672 4. Ecology and Development in the Third World. By Avijit Gupta. London: Routledge, 1988. Pp.vii + 80. £5.95. ISBN 0 415 00673 2. International Environmental Diplomacy. Edited by John E. Carroll. Cambridge: Cambridge University Press, 1988. Pp.299. £35. ISBN 0 521 33437 3.

Trophic differences, originations and extinctions during the Cenomanian and Maastrichtian stages of the Cretaceous

Abstract: Time normalized analyses of the feeding strategies of marine metazoan families which both originated and terminated during the Cenomanian and Maastrichtian shows that more primary consumers suffered extinction in the Maastrichtian than in the Cenomanian Each family was assigned a percentile “trophic score ”based on the feeding strategies that they employed The trophic categories are: Photosymbionts (P), which use the physiological products of endosymbionts and in some cases the endosymbionts themselves; first order consumers (C1); second order consumers (C2); third order consumers (C3) and detritus feeders (S) The trophic scores were analyzed as a bivariate plot of trophic categories versus percentages of origination/extinction The Cenomanian and Maastrichtian origination plots are similar in total percentages However, the extinction graphs show differences between the C1 and C2 categories The Cenomanian extinction graph shows a greater C2 value relative to C1, whereas the Maastrichtian extinction graph shows a C1 peak twice the value of the C2 peak

Knowledge Intensive Programming: A New Educational Computing Environment.

Abstract: A recent knowledge intensive computational environment (logic programming) and computer programming language paradigm (Prolog) is explored as an alternative to traditional educational computing procedural programming environments and languages.