A Complete Formulation of Baum-Conens' Conjecture for the Action of Discrete Quantum Groups

We formulate a version of Baum-Connes' conjecture for a discrete quantum group, building on our earlier work (\cite{GK}). Given such a quantum group \cla, we construct a directed family \{\cle_F \} of $C^*$-algebras ($F$ varying over some suitable index set), borrowing the ideas of \cite{cuntz}, such that there is a natural action of \cla on each \cle_F satisfying the assumptions of \cite{GK}, which makes it possible to define the "analytical assembly map", say $\mu^{r,F}_i$, $i=0,1,$ as in \cite{GK}, from the \cla-equivariant $K$-homolgy groups of \cle_F to the $K$-theory groups of the "reduced" dual \hat{\cla_r} (c.f. \cite{GK} and the references therein for more details). As a result, we can define the Baum-Connes' maps \mu^r_i : \stackrel{\rm lim}{\longrightarrow} KK_i^\cla(\cle_F,\IC) \raro K_i(\hat{\cla_r}), and in the classical case, i.e. when \cla is $C_0(G)$ for a discrete group, the isomorphism of the above maps for $i=0,1$ is equivalent to the Baum-Connes' conjecture. Furthermore, we verify its truth for an arbitrary finite dimensional quantum group and obtain partial results for the dual of $SU_q(2).$Comment: to appear in "K Theory" (special volume for H. Bass). A preliminary version was available as ICTP preprint since the early this yea

Food Insecurity, Family Structure and Agricultural Productivity: the role of Social Capital in Nigeria.

Replaced with revised version of paper 07/21/10.Food Security and Poverty,

Photolysis of alpha and beta-tin di-iodide

Imperial Users onl

Food insecurity and childhood obesity: beyond categorical and linear representations

Previous work on the relationship between food insecurity and childhood overweight has lead to a wide array of answers – some have found a positive relationship, others no relationship, and still others a negative relationship. This previous work has shared one thing in common – all have used parametric models. In this paper we move beyond parametric models by using non-parametric models. With data from the 1999-2002 National Health and Nutrition Examination Survey (NHANES) and a wide array parametric methods, we find evidence across different samples of a positive relationship, no relationship, and a negative relationship between childhood overweight and food insecurity. When we turn to non-parametric methods, however, this ambiguity across samples is not as prevalent. Instead, across different samples, we find (a) increases in the probability of food insecurity in the middle of the BMI distribution, (b) increases in the probability at the very high end of the BMI, and (c) no relationship across the entire distribution. We present some parametric models that roughly mimic these relationships. Our results indicate that efforts to reduce food insecurity will either have no impact on childhood overweight or would lead to reductions in childhood overweight.Food Consumption/Nutrition/Food Safety, Food Security and Poverty,

Computer Adoption and Returns in Transition: Theory Appendix

Across nine transition economies, it is the young, educated, English-speaking workers with the best access to local telecommunications infrastructures that work with computers. These workers earn about 25% more than do workers of comparable observable skills who do not use computers. Controlling for likely simultaneity between computer use at work and labor market earnings makes the apparent returns to computer use disappear. These results are corroborated using Russian longitudinal data on earnings and computer use on the job. High costs of computer use in transition economies suppress wages that firms can pay their workers who use computers.sorting; computer adoption; Returns; earnings; technology; Eastern Europe; Central Asia

Computer Adoption and Returns in Transition

Across nine transition economies, it is the young, educated, English-speaking workers with the best access to local telecommunications infrastructures that work with computers. These workers earn about 25% more than do workers of comparable observable skills who do not use computers. Controlling for likely simultaneity between computer use at work and labor market earnings makes the apparent returns to computer use disappear. These results are corroborated using Russian longitudinal data on earnings and computer use on the job. High costs of computer use in transition economies suppress wages that firms can pay their workers who use computers.

Three essays on food insecurity and child welfare

Three major issues affecting the welfare of children are investigated in three papers in this dissertation. These issues are the intra-household allocation of resources, food insecurity and obesity. The first two papers are focused on the issue of intra-household allocation of food resources and food insecurity in a developing country setting, namely Zimbabwe, while the relationship between food insecurity and obesity is investigated n the United States. In the first paper, a 2004 household survey of children in Zimbabwe is utilized to investigate differences in self-reports of food insecurity. A bivariate ordered probit regression is utilized to investigate any differences in reports of food insecurity between boys and girls. Findings reveal that all categories of children report roughly the same level of food security with the exception of orphan girls, who are significantly more likely to report food insecurity. The second paper is also focused on the intra-household allocation of food, this time between adults and children. Bivariate comparisons are utilized to highlight the magnitude of differences in the perception of food inadequacy and food insecurity, while bivariate probit regressions provide more insight into sources of these differences. Children are more likely than adults to report food security, although the differences are not uniform across households. A substantial number of households have children who are food inadequate or food insecure while the adult is not. In addition, there is evidence of a tendency to protect younger children and discriminate against female orphans in food distribution. The third paper utilizes nonparametric approaches and two nationally representative data sets to investigate the relationship between food insecurity and obesity in the United States. Nonparametric approaches are utilized to portray possible subtleties in the relationship between food insecurity and obesity over the full range of body mass index (BMI)-based percentiles of children in different racial and socioeconomic categories. The relationship between food insecurity and childhood obesity is revealed to be nonlinear and complex. More specifically, there is a strong positive association between food insecurity and age-gender based BMI percentiles for children who are low food secure or very low food secure. This positive association is consistent across a range of racial and socio-economic subgroups, and also across both data sets