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[en] Complete text of publication follows. Analogous to color CRTs, the aurora is a visual manifestation of the bombardment of atomic and molecular neutrals in the upper atmosphere by magnetic field-guided energetic charged particles (mainly electrons) from above. Based on this framework, the magnetosphere is the source of energetic particles, whereas the ionosphere is merely a passive 'illuminated target'. However, it is not clear if the magnetosphere is acting along in the energization of the particles because the energization occurs at the magnetosphere-ionosphere interface. The discovery of suppression of auroral acceleration events in sunlight [Newell et al., 1996] provides a new interpretation - the ionosphere is also playing an active role in the auroral production. The auroral sunlight effect is often attributed to an ionospheric feedback mechanism in which the background ionospheric conductance determines if an acceleration is required. However, a relationship between the background ionospheric conductance and the aurora has not been identified. In this presentation, we provide solid evidence to confirm that the ionospheric conductance plays a key role in modulating auroral intensity to a degree that may surpass its source's manipulation. This study is based on 56,675 Earth's disk FUV images of the polar regions acquired by TIMED/GUVI between February 2002 and November 2007. It is found that the occurrence rate of visible aurora reduces when the polar ionosphere is exposed to sunlight. Furthermore, the energy flux carried by precipitating electrons shows anti-correlation with the ionospheric background conductance. Suppression of the auroral energy flux is also found to continue in twilight until the ionosphere is totally in darkness - a strong evidence of ionospheric manipulation because the magnetospheric sunlight condition does not change. The present study suggests a new mechanism that governs our space disturbances, in addition to the more familiar magnetic field reconnection.
[en] We report on the occurrence of negative-phase-velocity (NPV) planewave propagation in the ergosphere of a rotating black hole. By implementing the Kerr metric, it is demonstrated that regions of NPV propagation are concentrated at the equator of the ergosphere, while NPV propagation is less common towards the polar regions. Increasing the angular velocity of the black hole exaggerates the NPV concentration at the equator. NPV propagation is not observed outside the stationary limit surface
[en] The City of Iqaluit is an Arctic community that is very susceptible to the stresses of climate change. The city is challenged by increased flooding, coastal erosion and ground instability caused by melting of the permafrost layer. In response, the City of Iqaluit has created policies to reduce greenhouse gases and act on climate change. A project has also been launched to develop adaptation strategies, with particular focus on infrastructure vulnerability given the environmental and climate change in the Canadian Arctic. The purpose of the study is to evaluate the biophysical exposure and hazards on Arctic coasts subject to effects of climate change, identify past and current management strategies used to manage risks in coastal communities which have already experienced environmental change, and to evaluate the adaptive capacity of communities for dealing with coastal hazards throughout the Arctic. This document identified the risks to Iqaluit's infrastructure, including buildings, roads, water supply, wastewater treatment and waste disposal systems. Adaptation options were also developed. These ranged from educational programs and retrofits to policy changes and building standard amendments. refs., tabs., figs