Statistical Mechanics of 2+1 Gravity From Riemann Zeta Function and Alexander Polynomial:Exact Results

In the recent publication (Journal of Geometry and Physics,33(2000)23-102) we demonstrated that dynamics of 2+1 gravity can be described in terms of train tracks. Train tracks were introduced by Thurston in connection with description of dynamics of surface automorphisms. In this work we provide an example of utilization of general formalism developed earlier. The complete exact solution of the model problem describing equilibrium dynamics of train tracks on the punctured torus is obtained. Being guided by similarities between the dynamics of 2d liquid crystals and 2+1 gravity the partition function for gravity is mapped into that for the Farey spin chain. The Farey spin chain partition function, fortunately, is known exactly and has been thoroughly investigated recently. Accordingly, the transition between the pseudo-Anosov and the periodic dynamic regime (in Thurston's terminology) in the case of gravity is being reinterpreted in terms of phase transitions in the Farey spin chain whose partition function is just a ratio of two Riemann zeta functions. The mapping into the spin chain is facilitated by recognition of a special role of the Alexander polynomial for knots/links in study of dynamics of self homeomorphisms of surfaces. At the end of paper, using some facts from the theory of arithmetic hyperbolic 3-manifolds (initiated by Bianchi in 1892), we develop systematic extension of the obtained results to noncompact Riemannian surfaces of higher genus. Some of the obtained results are also useful for 3+1 gravity. In particular, using the theorem of Margulis, we provide new reasons for the black hole existence in the Universe: black holes make our Universe arithmetic. That is the discrete Lie groups of motion are arithmetic.Comment: 69 pages,11 figures. Journal of Geometry and Physics (in press

Regional climate, federal land management, and the social-ecological resilience of southeastern Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2007Complex systems of humans and nature often experience rapid and unpredictable change that results in undesirable outcomes for both ecosystems and society. In circumpolar regions, where multiple converging drivers of change are reshaping both human and natural communities, there is uncertainty about future dynamics and the capacity to sustain the important interactions of social-ecological systems in the face of rapid change. This research addresses this uncertainty in the region of Southeast Alaska, where lessons learned from other circumpolar regions may not be applicable because of unique social and ecological conditions. Southeast Alaska contains the most productive and diverse ecosystems at high latitudes and a human population almost entirely isolated and embedded in National Forest lands; these qualities underscore the importance of the region's climate and federal management systems, respectively. This research presents a series of case studies of the drivers, dynamics, and outcomes of change in regional climate and federal management, and theoretically grounds these studies to understand the regional resilience to change. Climate change in Southeast Alaska is investigated with respect to impacts on temperate rainforest ecosystems. Findings suggest that warming is linked to emergence of declining cedar forests in the last century. Dynamics of federal management are investigated in several studies, concerning the origins and outcomes of national conservation policy, the boom-bust history of the regional timber economy, and the factors contributing to the current 'deadlock' in Tongass National Forest management. Synthesis of case study findings suggests both emergent phenomena (yellow-cedar decline) and cyclic dynamics (timber boom-bust) resulting from the convergence of ecological and social drivers of change. Adaptive responses to emergent opportunities appear constrained by inertia in management philosophies. Resilience to timber industry collapse has been variable at local scales, but overall the regional economy has experienced transition while retaining many of its key social-ecological interactions (e.g., subsistence and commercial uses of fish and wildlife). An integrated assessment of regional datasets suggests a high integrity of these interactions, but also identifies critical areas of emergent vulnerability. Overall findings are synthesized to provide policy and management recommendations for supporting regional resilience to future change.Introduction : Southeast Alaska as a social-ecological system -- Climate change and forest decline in Southeast Alaska -- Significance of wilderness conservation in Southeast Alaska : outcomes of the Alaska lands debate over the Tongass National Forest -- Dynamics of federal land management during the 20th century -- Factors influencing the reorganization of federal land management -- Conclusions : regional dynamics and social-ecological resilience of Southeast Alaska

Tiludronate and clodronate do not affect bone structure or remodeling kinetics over a 60 day randomized trial

Background Tiludronate and clodronate are FDA-approved bisphosphonate drug therapies for navicular disease in horses. Although clinical studies have determined their ability to reduce lameness associated with skeletal disorders in horses, data regarding the effect on bone structure and remodeling is lacking. Additionally, due to off-label use of these drugs in young performance horses, effects on bone in young horses need to be investigated. Therefore, the purpose of this randomized, experimental pilot study was to determine the effect of tiludronate and clodronate on normal bone cells, structure and remodeling after 60 days in clinically normal, young horses. Additionally, the effect of clodronate on bone healing 60 days after an induced defect was investigated. Results All horses tolerated surgery well, with no post-surgery lameness and all acquired biopsies being adequate for analyses. Overall, tiludronate and clodronate did not significantly alter any bone structure or remodeling parameters, as evaluated by microCT and dynamic histomorphometry. Tiludronate did not extensively impact bone formation or resorption parameters as evaluated by static histomorphometry. Similarly, clodronate did not affect bone formation or resorption after 60 days. Sixty days post-defect, healing was minimally affected by clodronate. Conclusions Tiludronate and clodronate do not appear to significantly impact bone tissue on a structural or cellular level using standard dose and administration schedules

The role of skills: from worklessness to sustainable employment with progression : UK Commission for Employment and Skills Evidence Report no. 38

This study is shaped by the recognition that while there has been a great deal of policy development around the transition from unemployment and inactivity to employment over the last decade, policy can still be informed about how best to nurture sustainable employment for those at risk of labour market exclusion. There remain challenges associated with, for example, the cost-effectiveness of intervention, the „low pay no pay‟ cycle and access to training. As a consequence, the opportunities for sustainable progression, upward social mobility and alleviating poverty remain unrealised for many workers in lower paid occupations. The methodology underpinning this study is predominantly based on a literature search and review of the research and evidence base post 2005. This is supplemented with the development of four international case studies (Australia, Denmark, Germany, United States contained in a separate annex) and an e-consultation with country experts

The role of skills from worklessness to sustainable employment with progression

This study is shaped by the recognition that while there has been a great deal of policy development around the transition from unemployment and inactivity to employment over the last decade, policy has not been sufficiently informed about how best to nurture sustainable employment for those at risk of labour market exclusion. The review focused on evidence from 2005: it provides a review of data, UK and international literature and, incorporates findings from four international case studies ( Australia, Germany, Denmark and the United States. The report provides an overview of the economic context for low pay and low skilled work and highlights the need for a continuing commitment to promoting opportunities in the labour market as a means of progression and alleviating poverty and encouraging social mobility. The report argues that there is an inextricable link between skills and ‘better jobs’. The authors conclude that a long-term view is required to decide how best to support someone at the point of worklessness: to address employability barriers in the short-term; and prepare the individual to retain, and progress in, employment. The concept of career is explored as a framework for progression: a combination of career guidance, a career / personal development plan and career management skills are identified as tools to raise aspiration and enable individual’s to take action once they are in work to support their own progression. Thinking about the workplace, the report reviews the evidence on the role of job design, line management and progression pathways in facilitating workplace learning as a route to progression

Relationship Between Tree Canopy Cover, Impervious Surfaces, & Bird Biodiversity in Urban Parks in Nashville, Tennessee​

Bird diversity is an indicator of the overall biodiversity in urban green spaces. Identifying factors associated with urban green spaces that strongly influence bird biodiversity can inform the development and management of urban green spaces. Parks with larger areas of impervious surfaces were predicted to have lower bird diversity than those with more tree canopy coverage. This study used iTree Canopy to determine the percentage of tree canopy and impermeable surfaces for four different areas of urban parks in Nashville, Tennessee. Two parks were closer to the urban core and two were farther away. Tree canopy and impermeable surface cover were compared to biodiversity of bird species determined from acoustic song meter recordings within the parks. Preliminary analysis of the data suggests that parks with higher percentages of impermeable areas relative to tree canopy had lower overall bird biodiversity. Managing parks for more tree canopy coverage can enhance urban bird diversity