Purpose -The purpose of this paper is to develop understanding of the role of small to medium-sized enterprises (SMEs) in relation to sustainable supply chain management, i.e. how corporate social responsibility (CSR) is integrated in their relationship with customers and suppliers. Design/methodology/approach -Drawing from a survey of CSR requirements among 410 Spanish SMEs, the paper examines the extent to which SMEs receive social and environmental requirements from diverse customer typologies and the extent to which they pass on such requirements to different supplier typologies. Findings -Based on survey results, it is concluded that large businesses are the most demanding customers in terms of the CSR requirements imposed to their SME suppliers. In turn, SMEs are able to transfer the requests received from their (larger) customers to their own suppliers. Research limitations/implications -The data are confined to companies located in a particular region (Catalonia in Spain), which questions its generalizability to other geographical contexts. Practical implications -The research shows that small and medium companies can be effective in spreading the CSR requirements received from large companies through the supply chain. Originality/value -The paper contributes to research on sustainable supply chain management from the SME perspective and offers a systematic analysis of the CSR activities of SMEs, both as suppliers and buyers. In addition, it proposes a rigorous way to measure the CSR-related supply chain pressure.

The authors studied the relationship between the antioxidant system and cognitive functions in a group of 36 early and continuously treated phenylketonuric (PKU) patients (mean age=9.7 years) and 29 controls. The authors measured antioxidant cofactors and free radical damage markers in plasma (selenium, retinol, tocopherol, coenzyme Q10, malondialdehide) and antioxidant enzymes in red blood cells (glutathione peroxidase, catalase, superoxide dismutase). The authors used neuropsychological tests to screen for several cognitive functions. PKU patients showed significantly lower values of selenium, coenzyme Q10, and catalase, and significantly higher levels of malondialdehide. PKU patients showed a significantly negative correlation between plasma selenium concentrations and several Conner's Continuous Performance Test measures (more omission errors, fluctuating attention and inconsistency of response times, and slowing reaction time as the test progressed). Selenium deficiency was thus associated with a worsened performance on the Conner's Continuous Performance Test among PKU patients. In conclusion, it is important not only to control blood Phe levels in PKU but also other nutritional components such as selenium. Selenium status seems to be associated with attention functions in these PKU patients.

A new direction of research in competitive location theory incorporates theories of consumer choice behavior in its models. Following this direction, the present article studies the importance of consumer behavior with respect to distance or transportation costs in the optimality of locations obtained by traditional competitive location models. We consider various ways of defining a key parameter in the basic maximum capture model (MAXCAP). This parameter will indicate a number of ways to take distance into account based on several consumer choice behavior theories. The optimal locations and the deviation in demand -captured when the optimal locations of the other models are used instead of the true ones -are computed for each model. We present a metaheuristic based on GRASP and the tabu search procedure to solve all the models. Computational experience and an application to a 55-node network are also presented.JEL classification: C61, R12, R53

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