Streptococcus pneumoniae isolates causing invasive disease at a large tertiary institute in Singapore from 2000 to 2007 were serotyped, with 84 (43.8 %) and 159 (82.8 %) isolates belonging to serotypes covered by the pneumococcal heptavalent conjugate and polysaccharide vaccines, respectively. All non-meningitis isolates were susceptible to penicillin, and the attributable mortality was 21.4 %. Patients who fulfilled the US Advisory Committee on Immunization Practices criteria for vaccination with the pneumococcal polysaccharide vaccine comprised 74.0 % of the study cohort and had a significantly higher mortality risk.

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Non-human primates housed in zoos and laboratories often exhibit reduced activity and this poses welfare concerns. We examined the effects of enclosure types of differing size and environmental complexity on the activities of two species of callitrichids. We found that cotton-top tamarins housed in an enclosure of larger size and more environmental complexity showed higher activity levels, which was mainly contributed by more feeding/foraging activity. By contrast, Goeldi's monkeys housed in an enclosure of larger size and more environmental complexity showed lower activity levels, which was mainly contributed by less locomotory activity. In both species, off-exhibit groups housed in smaller enclosures did not show significantly less locomotory activity which would have been expected, as larger availability spaces should allow more opportunities for locomotion. Furthermore, the feeding enrichment had significant effects on increased feeding/foraging activity for both cotton-top tamarins and Goeldi's monkeys, irrespective of enclosure type. These results suggested that environmental complexity (or application of feeding enrichment) that provided more opportunities for natural foraging could have a larger effect on overall activity levels compared with larger enclosure sizes that should provide more locomotion opportunities. More importantly, it showed that even when enclosure space and complexity were limited, increased opportunities for foraging through the application of enrichment could increase species-typical behaviours. Such inexpensive, easy to implement enrichment methods should be applied to provide more complex environments for captive non-human primates, particularly in situations where there are logistical and/or cost constraints to the modification of physical exhibits.

This paper presents a new robust decentralized variable structure control (DVSC) to stabilize a class of perturbed nonlinear large-scale systems. Only the bounds of perturbations, disturbances and interconnections of the system are needed. Based on Lyapunov theory, the DVSC is designed such that a Lyapunov function converges to a composite switching hyperplane in finite time, at least with an exponential rate. Our design method need not use the dynamic compensation or the integral of interconnections in the sliding mode definition, or the hierarchical control. Furthermore, both the convergence rate and the hitting time can be assigned. Finally, a two-pendulum system is given to illustrate the design method.

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