Tangential Structures on Toric Manifolds, and Connected Sums of Polytopes

We extend work of Davis and Januszkiewicz by considering {\it omnioriented} toric manifolds, whose canonical codimension-2 submanifolds are independently oriented. We show that each omniorientation induces a canonical stably complex structure, which is respected by the torus action and so defines an element of an equivariant cobordism ring. As an application, we compute the complex bordism groups and cobordism ring of an arbitrary omnioriented toric manifold. We consider a family of examples $B_{i,j}$, which are toric manifolds over products of simplices, and verify that their natural stably complex structure is induced by an omniorientation. Studying connected sums of products of the $B_{i,j}$ allows us to deduce that every complex cobordism class of dimension >2 contains a toric manifold, necessarily connected, and so provides a positive answer to the toric analogue of Hirzebruch's famous question for algebraic varieties. In previous work, we dealt only with disjoint unions, and ignored the relationship between the stably complex structure and the action of the torus. In passing, we introduce a notion of connected sum # for simple $n$-dimensional polytopes; when $P^n$ is a product of simplices, we describe P^n# Q^n by applying an appropriate sequence of {\it pruning operators}, or hyperplane cuts, to $Q^n$.Comment: 22 pages, LaTeX2e, to appear in Internat. Math. Research Notices (2001

Fresh Perspectives 4 – Ethical consumerism: development of a global trend and its impact on development

Key messages: Consumers increasingly wish to shop ethically, but require clearer navigation of the ethical categories; Third-party accreditation systems are proving an effective mechanism to formulate and communicate ethical attributes to consumers; Ethical issues are entering the mainstream, offering increased opportunities for developing countries; Domestic and regional markets in developing countries for value-added and quality products are growing

The use of field-programmable gate arrays for the hardware acceleration of design automation tasks

This paper investigates the possibility of using Field-Programmable Gate Arrays (Fr’GAS) as reconfigurable co-processors for workstations to produce moderate speedups for most tasks in the design process, resulting in a worthwhile overall design process speedup at low cost and allowing algorithm upgrades with no hardware modification. The use of FPGAS as hardware accelerators is reviewed and then achievable speedups are predicted for logic simulation and VLSI design rule checking tasks for various FPGA co-processor arrangements

Toric Genera

Our primary aim is to develop a theory of equivariant genera for stably complex manifolds equipped with compatible actions of a torus T^k. In the case of omnioriented quasitoric manifolds, we present computations that depend only on their defining combinatorial data; these draw inspiration from analogous calculations in toric geometry, which seek to express arithmetic, elliptic, and associated genera of toric varieties in terms only of their fans. Our theory focuses on the universal toric genus \Phi, which was introduced independently by Krichever and Loeffler in 1974, albeit from radically different viewpoints. In fact \Phi is a version of tom Dieck's bundling transformation of 1970, defined on T^k-equivariant complex cobordism classes and taking values in the complex cobordism algebra of the classifying space. We proceed by combining the analytic, the formal group theoretic, and the homotopical approaches to genera, and refer to the index theoretic approach as a recurring source of insight and motivation. The resultant flexibility allows us to identify several distinct genera within our framework, and to introduce parametrised versions that apply to bundles equipped with a stably complex structure on the tangents along their fibres. In the presence of isolated fixed points, we obtain universal localisation formulae, whose applications include the identification of Krichever's generalised elliptic genus as universal amongst genera that are rigid on SU-manifolds. We follow the traditions of toric geometry by working with a variety of illustrative examples wherever possible. For background and prerequisites we attempt to reconcile the literature of east and west, which developed independently for several decades after the 1960s.Comment: 35 pages, LaTeX. In v2 references made to the index theoretical approach to genera; rigidity and multiplicativity results improved; acknowledgements adde

Quality of schooling and inequality of opportunity in health

This paper explores the role of quality of schooling as a source of inequality of opportunity in health. Substantiating earlier literature that links differences in education to health disparities, the paper uses variation in quality of schooling to test for inequality of opportunity in health. Analysis of the 1958 NCDS cohort exploits the variation in type and quality of schools generated by the comprehensive schooling reforms in England and Wales. The analysis provides evidence of a statistically significant and economically sizable association between some dimensions of quality of education and a range of health and health-related outcomes. For some outcomes the association persists, over and above the effects of measured ability, social development, academic qualifications and adult socioeconomic status and lifestyle

Long-term effects of school quality on health and lifestyle: evidence from comprehensive schooling reforms in England

Members of the National Child Development Study cohort attended very different types of secondary schools, as their schooling lay within the transition period of the comprehensive education reform in England and Wales. This provides a natural setting to explore the impact of educational attainment and of school quality on health and health-related behavior later in life. We use a combination of matching methods and parametric regressions to deal with selection effects and to evaluate differences in adult health outcomes and health-related behavior for cohort members exposed to the old selective and to the new comprehensive educational systems

Local Monopsony Power in the Market for Broilers - Evidence from a Farm Survey

The exercise of monopsony power by broiler processing firms is plausible because production occurs within localized complexes, which limits the number of integrators with whom growers can contract. In addition, growers face distinct hold-up risks as broiler production requires a substantial investment in specific assets and most production contracts do not involve long-term purchasing commitments by integrators. This paper provides an initial exploration of the links between the local concentration of broiler integrators and grower compensation under production contracts using data from the 2006 broiler version of USDA’s Agricultural Resource Management Survey. Results of this preliminary study, which accounts for characteristics of the operation and specific features of the production contract, suggest a small but economically meaningful effect of concentration on grower concentration. Limitations of the current analysis and future possible model extensions are discussed.poultry, broilers, market power, monopsony, production contracts, Livestock Production/Industries, Marketing,