The ring of global sections of multiples of a line bundle on a toric variety

In this article we prove, in a simple way, that for any complete toric variety, and for any Cartier divisor, the ring of global sections of multiples of the line bundle associated to the divisor is finitely generated.Comment: To appear in Proceedings of the AMS, one figure, 5 pages, Author-supplied DVI file available at: http://calli.matem.unam.mx/investigadores/javier/investigacion.html LaTeX2e Sub-Class: 14C20 14M2

Credit allocation based on journal impact factor and coauthorship contribution

Some research institutions demand researchers to distribute the incomes they earn from publishing papers to their researchers and/or co-authors. In this study, we deal with the Impact Factor-based ranking journal as a criteria for the correct distribution of these incomes. We also include the Authorship Credit factor for distribution of the incomes among authors, using the geometric progression of Cantor's theory and the Harmonic Credit Index. Depending on the ranking of the journal, the proposed model develops a proper publication credit allocation among all authors. Moreover, our tool can be deployed in the evaluation of an institution for a funding program, as well as calculating the amounts necessary to incentivize research among personnel.Comment: 9 pages; 3 figures; 2 table

Does More Mean Better? Sibling Sex Composition and the Link between Family Size and Children’s Quality

Exogenous variation in fertility from parental preferences for sex-mix among their children is used to identify the causal effect of family size on several measures associated with either the allocation of resources towards children within the household or the outcomes of these investments. Results using data from Colombia suggest that family size has negative effects on average child quality. Children from larger families have accumulated almost 1 year less of education, are less likely to enroll in school and about twice as likely to be held back in school. A larger family also increases the likelihood that oldest siblings share a room and reduces the chance that they have access to clean water and sanitary sewer facilities by approximately 15 percentage points, suggesting the existence of negative effects arising from limited household resources. Mothers in these households have less labor participation (over 27 percentage points) and their oldest children are also more likely to engage in labor activities or domestic chores. Children from larger families are also more likely to be physically or psychologically affected by domestic violence within the household. Other less robust but informative calculations using data on anthropometrics, morbidity and immunization records also fit well with the main results of the quasi-experimental research design. The evidence presented here is consistent with the tradeoff between the number and quality of children implied by the theoretical interdependence in their prices and is robust to different specifications, estimation methods and alternative sub-samples.fertility, household behavior, children’s well-being, Colombia