The wedding of modified dynamics and non-exotic dark matter in galaxy clusters

We summarize the status of Modified Newtonian Dynamics (MOND) in galaxy clusters. The observed acceleration is typically larger than the acceleration threshold of MOND in the central regions, implying that some dark matter is necessary to explain the mass discrepancy there. A plausible resolution of this issue is that the unseen mass in MOND is in the form of ordinary neutrinos with masses just below the experimentally detectable limit. In particular, we show that the lensing mass reconstructions of the clusters 1E0657-56 (the bullet cluster) and Cl0024+17 (the ring) do not pose a new challenge to this scenario. However, the mass discrepancy for cool X-ray emitting groups, in which neutrinos cannot cluster, pose a more serious problem, meaning that dark baryons could present a more satisfactory solution to the problem of unseen mass in MOND clusters.Comment: to appear in World Scientific, proceedings of DARK 200

The Fractional Quantum Hall Effect of Tachyons in a Topological Insulator Junction

We have studied the tachyonic excitations in the junction of two topological insulators in the presence of an external magnetic field. The Landau levels, evaluated from an effective two-dimensional model for tachyons, and from the junction states of two topological insulators, show some unique properties not seen in conventional electrons systems or in graphene. The $\nu=1/3$ fractional quantum Hall effect has also a strong presence in the tachyon system.Comment: 5 pages, 3 figure

Dificultades y posibilidades del algoritmo de optimización de enjambre de partículas para la planificación contemporánea espacial del bosque

We describe here an example of applying particle swarm optimization (PSO) — a population-based heuristic technique — to maximize the net present value of a contemporary southern United States forest plan that includes spatial constraints (green-up and adjacency) and wood flow constraints. When initiated with randomly defined feasible initial conditions, and tuned with some appropriate modifications, the PSO algorithm gradually converged upon its final solution and provided reasonable objective function values. However, only 86% of the global optimal value could be achieved using the modified PSO heuristic. The results of this study suggest that under random-start initial population conditions the PSO heuristic may have rather limited application to forest planning problems with economic objectives, wood-flow constraints, and spatial considerations. Pitfalls include the need to modify the structure of PSO to both address spatial constraints and to repair particles, and the need to modify some of the basic assumptions of PSO to better address contemporary forest planning problems. Our results, and hence our contributions, are contrary to earlier work that illustrated the impressive potential of PSO when applied to stand-level forest planning problems or when applied to a high quality initial population.Se describe aquí un ejemplo de la aplicación de la optimización de enjambre de partículas (PSO) — una técnica heurística basada en la población — para maximizar el valor presente neto de un moderno plan de gestión del bosque del sur de los Estados Unidos, que incluye limitaciones espaciales y restricciones del flujo de madera. Cuando se inicia con condiciones iniciales factibles definidas aleatoriamente, y en sintonía con algunas modificaciones adecuadas, el algoritmo PSO converge gradualmente sobre su solución final y suministra los valores de la función objetivo. Sin embargo, sólo el 86% del valor global óptimo podría lograrse usando la heurística PSO modificada. Los resultados de este estudio sugieren que bajo condiciones de arranque aleatorio de la población inicial, la heurística PSO puede tener una aplicación más bien limitada a los problemas de planificación forestal con objetivos económicos, restricciones de flujo de madera y consideraciones espaciales. Las dificultadas incluyen la necesidad de modificar la estructura de PSO para abordar tanto las limitaciones espaciales como para reparar las partículas, y la necesidad de modificar algunos de los supuestos básicos de PSO para abordar mejor los problemas contemporáneos de la planificación forestal. Nuestros resultados, y por lo tanto nuestra aportación, son contrarios a trabajos anteriores que ilustran el impresionante potencial de PSO cuando se aplica a problemas de planificación forestal a nivel de rodal o cuando se aplica a una población de calidad inicial alta

CO2 emission accounts of Russia's constituent entities 2005-2019

Constituent entities which make up Russia have wide-ranging powers and are considered as important policymakers and implementers of climate change mitigation. Formulation of CO2 emission inventories for Russia’s constituent entities is the priority step in achieving emission reduction. Russia is the world’s largest exporter of oil and gas combined and the fourth biggest CO2 emitter, so it’s efforts in mitigating CO2 emissions are globally significant in curbing climate change. However, the existing emission inventories only present national CO2 emissions; the subnational emission details are missing. In addition, the emission factors are not country-specific and energy activity data by fossil energy types and sectors are not sufficiently detailed. In this study, the CO2 emission inventories of Russia and its 82 constituent entities from 2005 to 2019 are constructed. The emission inventories include energy-related emissions with 89 socio-economic sectors and 17 energy types and process-related emissions. The uniformly formatted emission inventories can be a reference for in-depth analysis of emission characteristics and emission-related studies of Russia