Nurse Rostering Problems: A Bibliographic Survey

10.1016/S0377-2217(03)00021-3European Journal of Operational Research1513447-460EJOR

Pharmaceutical pollution of the world's rivers

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world's rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals

When do derivatives add value in asset allocation problems for pension funds?

Recent surveys indicate that many pension-fund participants aim for higher retirement income security. We investigate the added value of including derivatives in the portfolio of pension funds to achieve this goal. To do so, we define preferences that incorporate specific features of pension funds, but we also report performance among several key criteria used in practice. Furthermore, we model explicitly that the equity market exhibits both jump risk and volatility risk. Our results show that even relatively small investments in derivatives can achieve improvements in certainty equivalent rates of return and other important performance measures. This confirms the intuition that the use of derivatives allows pension investors to make explicit risk and return trade- offs and diversify between diffusion risk, jump risk, and volatility risk