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Choice of crops is limited in dry agro-ecosystems. Senna, Cassia anguszifolia Vahl, a tropical medicinal plant, has potential as a dryland crop. This study was conducted to investigate gas exchange and leaf surface ultrastructural responses of senna to drought and foliar-applied nitrogen under greenhouse conditions. Drought was imposed cyclically as four, 1-wk spells by withholding water. Additional nitrogen was provided as a foliar treatment of 1% (w/v) urea at the end of each of first three drought cycles. Drought-stressed plants had the same net photosynthesis ([P.sub.net]) as well-watered plants until the leaf water potential dropped below approximately -0.8 MPa. Leaf water potential of approximately 2 MPa completely suppressed [P.sub.net]. Foliar nitrogen treatment increased [P.sub.net] > 30% in both water-stressed and well-watered plants. Intrinsic water use efficiency was unaffected by cyclic drought. Leaf area per plant increased 156% because of foliar nitrogen treatment in well-watered plants hut remained unchanged in drought-stressed plants. Stomatal count per leaflet decreased 25% or more because of drought regardless of foliar nitrogen treatment on either abaxial or adaxial leaf surface. Foliar nitrogen treatment decreased adaxial but increased abaxial stomatal count regardless of drought treatment. Trichome count was more than eight times greater on the abaxial than the adaxial leaf surface under any treatment combination. Adaxial trichome number increased under drought, but decreased under nitrogen treatment. Abaxial trichome count increased because of drought only in plants deprived of nitrogen treatment. Maintenance of high carbon gain and water use efficiency, drought deciduousness, and plasticity in stomatal and trichome counts under both drought and nitrogen stress appeared to confer stress tolerance in senna., DROUGHT AND LIMITED SOIL NITROGEN are among the most important environmental constraints that limit both crop choice and productivity in a wide range of agricultural ecosystems. Adoption of crops that [...]

This article derives a set of hypotheses to explain how drama can affect the behavior of the audience. First, theories of drama explain how to create a drama that involves the audience. Second, drama theory explains how confrontation leads to emotional response, cognitive reorientation, and character change within a drama, both fictional and real. A convergence theory of communication predicts that audience members who perceive the change in characters with whom they closely identify will be influenced to change their behavior. Cognitive image mapping is used to illustrate how these hypotheses could be tested with an entertainment-education drama about AIDS in Africa.

To estimate the impact of a mass media campaign to promote contraceptive use, a national longitudinal sample survey was conducted in September 1995 and March 1996. Recall of at least one television spot was 82.3%. Modern contraceptive use increased 2.1 percentage points. The conditional change regression analysis revealed that prior contraceptive intention and behavior, current ideation, and prior ideation were the best predictors of contraceptive behavior. The best predictor of ideation was prior level of ideation and recall of campaign messages. Thus, the campaign had a significant indirect effect on intention and behavior through its effect on ideation. Ideation was operationalized by combining cognitive, emotional and social factors from a predictive model of strategic communication and behavior change. No endogeneity (reciprocity) with contraceptive intention and use was found in the statistical models for either campaign recall or ideation, an indication that the ordinary regression was an appropriate method to estimate the path coefficients.

Longitudinal survey data from a panel of married women in Bangladesh is used to estimate the impact of a social network approach to family planning field worker communication and to test a theoretical model of behavior change that explains why women adopt modern contraceptives. Government field workers were trained to organize group discussions with women in the homes of opinion leaders located at central points in each village's social network. A set of intervening variables, referred to collectively as 'ideation', are derived from diffusion of innovation and social network theory to explain how the social network approach affects contraceptive behavior. The rate of increase in modern contraceptive use was found to be five times greater among women in the social network approach than among women who were visited by field workers at home. The impact of the social network approach on modern contraceptive use was almost double that of conventional field worker visits after controlling for the effects of prior contraceptive use and intention, prior home visits, and selected socio-demographic characteristics. Both approaches had the same degree of impact on ideation. The results confirm the influence of ideation on fertility change and suggest that family planning programs would benefit from training field workers to use a social network approach.

Reports that immigrants to Hawaii use the news media to assist in acculturation and to retain cultural pluralism. (FL)