The shape of hyperbolic Dehn surgery space

In this paper we develop a new theory of infinitesimal harmonic deformations for compact hyperbolic 3-manifolds with ``tubular boundary''. In particular, this applies to complements of tubes of radius at least R_0 = \arctanh(1/\sqrt{3}) \approx 0.65848 around the singular set of hyperbolic cone manifolds, removing the previous restrictions on cone angles. We then apply this to obtain a new quantitative version of Thurston's hyperbolic Dehn surgery theorem, showing that all generalized Dehn surgery coefficients outside a disc of ``uniform'' size yield hyperbolic structures. Here the size of a surgery coefficient is measured using the Euclidean metric on a horospherical cross section to a cusp in the complete hyperbolic metric, rescaled to have area 1. We also obtain good estimates on the change in geometry (e.g. volumes and core geodesic lengths) during hyperbolic Dehn filling. This new harmonic deformation theory has also been used by Bromberg and his coworkers in their proofs of the Bers Density Conjecture for Kleinian groups.Comment: 46 pages, 3 figure

Non-geometric veering triangulations

Recently, Ian Agol introduced a class of "veering" ideal triangulations for mapping tori of pseudo-Anosov homeomorphisms of surfaces punctured along the singular points. These triangulations have very special combinatorial properties, and Agol asked if these are "geometric", i.e. realised in the complete hyperbolic metric with all tetrahedra positively oriented. This paper describes a computer program Veering, building on the program Trains by Toby Hall, for generating these triangulations starting from a description of the homeomorphism as a product of Dehn twists. Using this we obtain the first examples of non-geometric veering triangulations; the smallest example we have found is a triangulation with 13 tetrahedra

Evidence of late Quaternary environmental change in a continental east Antarctic lake from lacustrine sedimentary pigment distributions

A sediment core from Progress Lake, one of the oldest lacustrine sequences in East Antarctica, contains distinct zones dating from a previous interglacial (most likely Marine Isotope Stage 5e, c. 125-115 kyr BP) and the present interglacial (Marine Isotope Stage 1), separated by a transition zone representing when the lake became sub-glacial. Profiles of fossil pigments, determined using high performance liquid chromatography and liquid chromatography-tandem mass spectrometry, show distinct differences in the photoautotrophic community during these two interglacial periods. The first was dominated by algae and purple phototrophic bacteria, with periods of photic zone euxinia indicated by pigments from anoxygenic phototrophic bacteria. Specific chlorophyll a derivatives reveal periods when grazing pressure impacted significantly on the phytoplankton community. The virtual absence of pigments in the transition zone reflects severe restriction of photoautotrophic activity, consistent with the take having become sub-glacial. Retreat of snow and ice in the late Holocene (3345 C-14 yr Bp) allowed establishment of a less diverse primary producer community, restricted to algae and cyanobacteria. Grazers were severely restricted and oxidative transformation was more important than during the previous interglacial. The pigment data provide a unique and detailed insight in to the evolution of the lake ecology over an interglacial-glacial-interglacial transition and strong evidence that the Marine Isotope Stage 5e interglacial in this region of coastal East Antarctica was several degrees warmer than at present

Post-16 Curriculum and Qualifications Reform in England and Scotland: lessons from home international comparisons

In this article we compare Curriculum 2000 and Higher Still, recent reforms of post-16 education in England and Scotland respectively. We draw on current and earlier research on the unification of academic and vocational learning in England, Scotland and other European countries in order to suggest areas for mutual learning to inform future curriculum and qualifications reform north and south of the Border. We highlight five of these - the conduct of the policy process, issues of progression, assessment, approaches to vocational education and key/core skills. In our conclusion we speculate on the possibility of either convergence or divergence of the English and Scottish upper secondary education systems as both evolve

Treatment of Abscessed Primary Molars Utilizing Lesion Sterilization and Tissue Repair: Literature Review and Report of Three Cases

Purpose: The purpose of this report was to review an emerging alternative treatment to pulpectomies and extractions for nonvital primary teeth called lesion sterilization and tissue repair (LSTR) and provide the results of three clinical case applications. LSTR is a noninstrumentation endodontic treatment that involves a triantibiotic mixture in a propylene glycol vehicle, which is used to disinfect root canal systems. This concept was developed by the cariology research unit of the School of Dentistry, Niigata University, Niigata, Niigata Prefecture, Japan. This article reviews the development of the technique, clinical procedures required for the technique, three clinical applications and radiographic documentation and follow-up, and a short literature review of the current evidence supporting its application in clinical practice

Developing professional skills in journalism through blogs

The curriculum for journalism is being forced to change because the traditional print-based and broadcast modes are being challenged by wide and easy access to online mass communication. Primarily, students need to develop proficiency in writing, editing and publishing. However, they are also expected to be skilled in the Web medium as they venture into their careers, and weblogs offer a dynamic platform to develop these skills. Based on a statistical summary of student comments on the performance criteria for a blog project, a focus group interview and survey results, this paper will discuss the findings from the introduction of a course-based blog to an undergraduate course in Hong Kong, including: (1) the technical challenge of making Web features; (2) the perception of proficiency in online publishing; (3) the evaluative skills developed through a peer-review process; and (4) the development of a learning community through writing in blogs. © 2011 Taylor & Francis.postprin