Meredythe Anne Scheflen

Meredythe Anne Scheflen, career missionary to Bolivia with World Gospel Mission (WGM), was the hostess for the CILA seminar team to the Bolivian Evangelical University (UEB). Here is more about this remarkable lady

Characterizing symmetric spaces by their Lyapunov spectra

We prove that closed negatively curved locally symmetric spaces are characterized up to isometry among all homotopy equivalent negatively curved manifolds by the Lyapunov spectra of the periodic orbits of their geodesic flows. This is done by constructing a new invariant measure for the geodesic flow that we refer to as the horizontal measure. We show that the Lyapunov spectrum of the horizontal measure alone suffices to locally characterize these locally symmetric spaces up to isometry. We associate to the horizontal measure a new invariant, the horizontal dimension. We tie this invariant to extensions of curvature pinching rigidity theorems for complex hyperbolic manifolds to pinching rigidity theorems for the Lyapunov spectrum. Our methods extend to give a rigidity theorem for smooth Anosov flows $f^{t}$ orbit equivalent to the geodesic flow $g^{t}_{X}$ of a closed negatively curved locally symmetric space $X$: $f^{t}$ is smoothly orbit equivalent to $g^{t}_{X}$ if and only if its Lyapunov spectra on all periodic orbits are a multiple of the corresponding Lyapunov spectra for $g^{t}_{X}$.Comment: 92 pages. Main result has been improved significantl

Let's get personal

Philip Butler has worked as an e-Learning adviser in post-16 education for 19 years. Here he describes his experiences and outlines what he believes to be the challenges faced by the NH

Red, White and Bicycle: RVA, France and the Bike Race, Blog 1

Student blog posts from the Great VCU Bike Race Book

Evolving Political Accountability in Kenya

published or submitted for publicationnot peer reviewe

Artemisinin: From Chinese Herbal Medicine to Modern Chemotherapy

Malaria is a disease that has blighted humankind since early times. The first antimalarial treatment available to Europeans was the dried bark of the cinchona tree from Peru. The main problem in its use was adulteration by other material. The ‘active principle’ was first extracted in 1820 and named quinine. It was found to be a more powerful and reliable drug than cinchona bark. Once its chemical structure had been determined, it was possible to synthesize substances chemically related to quinine that were equally powerful but could be manufactured industrially. Mepacrine (atabrine) was amongst the most successful, but had adverse side effects. To avoid these side effects, further chemical modification gave chloroquine, a highly successful drug. This sequence is a common way of converting an herbal remedy into a modern-style chemical drug. It parallels, to some extent, the process of potentiation common in traditional herbal medicine. By the 1970s, drug resistance had developed with chloroquine. To find and develop a new antimalarial drug that worked on an entirely different pharmacological principle, Chinese scientists turned to their herbal compendia (ben cao) and found that Artemisia annua (qing hao) was frequently mentioned as a treatment for intermittent fever. Whether, in view of the distinctive doctrines of Chinese medicine, it should be possible to extract an active principle as described above is discussed. After a very careful reading of the procedure given for the use of qing hao, an active substance, artemisinin, was extracted. Artemisinin has a truly remarkable chemical structure, and chemical modification produced artesunate, the drug of choice. To prevent the development of resistance, artesunate is used in combination with other antimalarial drugs. Modern pharmacology has largely ignored that other substances in artemisia and the cinchona bark may contribute to their therapeutic effect. This matter is also discussed