LDH level at diagnosis, mediastinal disease, and combined BM-positive/CNS-positive involvement are independent risk factors in children with mature B-cell NHL. Future studies should be developed to identify specific therapeutic strategies (immunotherapy) to overcome these risk factors and to identify the biologic basis associated with these prognostic factors in children with mature B-cell NHL.

S ocial scientists often attribute moderation of the political salience of ethnicity in ethnically diverse societies to the presence of cross-cutting cleavages-that is, to dimensions of identity or interest along which members of the same ethnic group may have diverse allegiances. Yet, estimating the causal effects of cross-cutting cleavages is difficult. In this article, we present experimental results that help explain why ethnicity has a relatively minor political role in Mali, an ethnically heterogeneous sub-Saharan African country in which ethnic identity is a poor predictor of vote choice and parties do not form along ethnic lines. We argue that the cross-cutting ties afforded by an informal institution called "cousinage" help explain the weak association between ethnicity and individual vote choice. The experimental research design we introduce may be useful in many other settings.

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