S. E. Harris

Osteoporosis and other diseases of bone loss are a major public health problem. Here it is shown that the statins, drugs widely used for lowering serum cholesterol, also enhance new bone formation in vitro and in rodents. This effect was associated with increased expression of the bone morphogenetic protein-2 (BMP-2) gene in bone cells. Lovastatin and simvastatin increased bone formation when injected subcutaneously over the calvaria of mice and increased cancellous bone volume when orally administered to rats. Thus, in appropriate doses, statins may have therapeutic applications for the treatment of osteoporosis.

The Circular Economy (CE) concept is receiving increasing global attention and has captivated many disciplines, from sustainability through to business and economics. There is currently a strong drive by companies, academics and governments alike to implement the CE. Numerous “circularity indicators” have emerged that measure material flow or recirculated value of a system (e.g. product or nation). However, if its implementation is to improve environmental performance of society, the action must be based on scientific evidence and quantification or it may risk driving “circularity for circularity's sake”. This paper, therefore, aims to review the recent circular economy literature that focuses on assessing the environmental implications of circularity of products and services. To do this we divide the system levels into micro (product level), meso (industrial estate/symbiosis) and macro (national or city level). A scoping literature review explores the assessment methods and indicators at each level. The results suggest that few studies compare circularity indicators with environmental performance or link the circularity indicators between society levels (e.g. the micro and macro-levels). However, adequate tools exist at each level (e.g. life cycle assessment (LCA) at the micro-level and multi-regional input-output (MRIO) analysis at the macro-level) to provide the ability to adequately assess and track the CE performance if placed within a suitable framework. The challenge to connect the micro and macro-levels remains. This would help understand the link between changes at the micro-level at the macro-level, and the environmental consequences. At the meso-level, industrial symbiosis continues to grow in potential, but there is a need for further research on the assessment of its contribution to environmental improvement. In addition, there is limited understanding of the use phase. For example, national monitoring programmes do not have indicators on stocks of materials or the extent of the circular economy processes (such as the reuse economy, maintenance and spare parts) which already contribute to the CE. The societal needs/functions framework offers a promising meso-level link to bridge the micro and macro-levels for assessment, monitoring and setting thresholds.

This paper reviews progress on tunable optical parametric oscillators. Topics considered include: parametric amplification of Gaussian beams: threshold; tuning techniques, spectral output, and stability; saturation and power output; spontaneous parametric emission; nonlinear materials; and far infrared generation.

We report the observation of a gain of approximately $\mathrm{exp}\left(11\right)$ at 41.8 nm in 8-times-ionized xenon. This extreme ultraviolet (XUV) laser is driven by a 10-Hz, 70-mJ circularly polarized femtosecond laser pulse. The laser is focused into Xe at pressures ranging from 5 to 12 torr. The laser is collisionally excited, with both the ions and electrons produced by field induced tunneling.