ABSTRACT
Energy systems of the future are envisaged to encompass multiple interacting autonomous entities. The theory of games provides the foundations for the design and analysis of such systems. This paper reviews models and results that would be of use for such analysis. Classically, games have involved players whose strategies are coupled only through the dependence of utility functions on strategies of other players. However, in many practical settings in the energy domain, system-level limitations bind the choices players can make. In 1965, Rosen (Econometrica33, 520-534 (doi:10.2307/1911749)) pioneered the study of a class of games where there is a common constraint, called a shared constraint, that couples the strategies available to the players. We discuss how this seemingly benign extension has important ramifications, ranging from the very definition of an equilibrium concept, to other key issues such as existence, uniqueness and efficiency of equilibria. We show how the presence of a shared constraint naturally leads to notions of a price and forms the motivations for more recent models. Although most of the paper has the character of a survey, occasionally we also prove new results.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'.
ABSTRACT
BACKGROUND: Dental caries is a multifactorial disease which requires a susceptible host, a cariogenic microflora, and a suitable substrate that must be present for a sufficient length of time. Tea is prepared by the infusion of dried leaves of the tea plant, Camellia sinensis, which contains bioactive compounds like polyphenols, flavonoids, and catechins that are thought to be responsible for the health benefits that have traditionally been attributed to tea. These compounds have multidimensional effects such as antibacterial action, inhibitory action on the bacterial and salivary amylase, and inhibition of acid production. AIMS: The aim of this study is to compare the antiplaque efficacy of 0.5% C. sinensis extract, 0.05% sodium fluoride, and 0.2% chlorhexidine gluconate mouthwash in children. MATERIALS AND METHODS: A randomized blinded controlled trial with 60 healthy children of age group 9-14 years was carried out. The subjects were randomly assigned to three groups, i.e. group A - 0.2% chlorhexidine gluconate, group B - 0.05% sodium fluoride, and group C - 0.5% C. sinensis extract, with 20 subjects per group. Plaque accumulation and gingival condition were recorded using plaque index and gingival index. Oral hygiene was assessed by simplified oral hygiene index (OHIS). Salivary pH was assessed using indikrom pH strips. Plaque, gingival, and simplified OHI scores as well as salivary pH were recorded at baseline, immediately after first rinse, after 1 week, and in the 2(nd) week. STATISTICAL ANALYSIS USED: The data were analyzed using a computer software program (SPSS version 17). Analysis of variance (ANOVA) tests were used to identify significant differences between the means of the study groups. Finally, paired t-tests were used to assess the significance of changes within each group between time periods. Critical P values of significance were set at 0.05 and the confidence level set at 95%. RESULTS: Mean plaque and gingival scores were reduced over the 2-week trial period in the experimental groups. Antiplaque effectiveness was observed in all groups, the highest being in group C (P < 0.05). Chlorhexidine gluconate and tea showed comparative effectiveness on gingiva better than sodium fluoride (P < 0.05). The salivary pH increase was sustained and significant in groups B and C compared to group A. Oral hygiene improvement was better appreciated in groups A and C. CONCLUSIONS: The effectiveness of 0.5% C. sinensis extract was more compared to 0.05% sodium fluoride and 0.2% chlorhexidine gluconate mouth rinses. It should be explored as a cost-effective and safe long-term adjunct to oral self-care of patients as it has prophylactic benefits with minimum side effects.
