Electric potential distributions at the interface between plasmasheet clouds

At the interface between two plasma clouds with different densities, temperatures, and/or bulk velocities, there are large charge separation electric fields which can be modeled in the framework of a collisionless theory for tangential discontinuities. Two different classes of layers were identified: the first one corresponds to (stable) ion layers which are thicker than one ion Lamor radius; the second one corresponds to (unstable) electron layers which are only a few electron Larmor radii thick. It is suggested that these thin electron layers with large electric potential gradients (up to 400 mV/m) are the regions where large-amplitude electrostatic waves are spontaneously generated. These waves scatter the pitch angles of the ambient plasmasheet electron into the atmospheric loss cone. The unstable electron layers can therefore be considered as the seat of strong pitch angle scattering for the primary auroral electrons

The nature of turbulence in OMC1 at the star forming scale: observations and simulations

Aim: To study turbulence in the Orion Molecular Cloud (OMC1) by comparing observed and simulated characteristics of the gas motions. Method: Using a dataset of vibrationally excited H2 emission in OMC1 containing radial velocity and brightness which covers scales from 70AU to 30000AU, we present the transversal structure functions and the scaling of the structure functions with their order. These are compared with the predictions of two-dimensional projections of simulations of supersonic hydrodynamic turbulence. Results: The structure functions of OMC1 are not well represented by power laws, but show clear deviations below 2000AU. However, using the technique of extended self-similarity, power laws are recovered at scales down to 160AU. The scaling of the higher order structure functions with order deviates from the standard scaling for supersonic turbulence. This is explained as a selection effect of preferentially observing the shocked part of the gas and the scaling can be reproduced using line-of-sight integrated velocity data from subsets of supersonic turbulence simulations. These subsets select regions of strong flow convergence and high density associated with shock structure. Deviations of the structure functions in OMC1 from power laws cannot however be reproduced in simulations and remains an outstanding issue.Comment: 12 pages, 8 figures, accepted A&A. Revised in response to referee. For higher resolution, see http://www.astro.phys.au.dk/~maikeng/sim_paper

Observations of spatial and velocity structure in the Orion Molecular Cloud

Observations are reported of H2 IR emission in the S(1) v=1-0 line at 2.121 microns in the Orion Molecular Cloud, OMC1, using the GriF instrument on the Canada-France-Hawaii Telescope. GriF is a combination of adaptive optics and Fabry-Perot interferometry, yielding a spatial resolution of 0.15" to 0.18" and a velocity discrimination as high as 1 km/s. Thanks to the high spatial and velocity resolution of the GriF data, 193 bright H2 emission regions can be identified in OMC1. The general characteristics of these features are described in terms of radial velocities, brightness and spatial displacement of maxima of velocity and brightness, the latter to yield the orientation of flows in the plane of the sky. Strong spatial correlation between velocity and bright H2 emission is found and serves to identify many features as shocks. Important results are: (i) velocities of the excited gas illustrate the presence of a zone to the south of BN-IRc2 and Peak 1, and the west of Peak 2, where there is a powerful blue-shifted outflow with an average velocity of -18 km/s. This is shown to be the NIR counterpart of an outflow identified in the radio from source I, a very young O-star. (ii) There is a band of weak velocity features (<5 km/s) in Peak 1 which may share a common origin through an explosive event, in the BN-IRc2 region, with the fast-moving fingers (or bullets) to the NW of OMC1. (iii) A proportion of the flows are likely to represent sites of low mass star formation and several regions show multiple outflows, probably indicative of multiple star formation within OMC1. The high spatial and velocity resolution of the GriF data show these and other features in more detail than has previously been possible.Comment: 27 pages, 19 figures, submitted to A&A Version 2: Several additions, including a section on protostellar candidates in OMC1, have been made based on the referee's suggestions v3: corrected typograph

Inclusive Urban Planning – Promoting Equality and Inclusivity in Urban Planning Practices

Number of challenges exists to encouraging sustainability in urbanisation in the developing world. A common approach over the last 30 years, has been to focus on a “growth-first” plan for development, particularly in new urban areas. This entails encouraging the greatest amount of economic growth through country-level and local planning practices. In theory, growth-first development planning leads to a relatively equitable urban society, however in practice due to policy decisions and externalities, this has not been the case. Inclusive urbanisation seeks to address issues in access to urban services and the equitability of the urban socio-economic structure through ensuring that all participants have access to the same level of services and opportunities as each other. Most often this manifests through ensuring that rights for marginalised or previously-excluded groups, such as women and children, migrant workers or refugees, are accounted for in planning policies, and plans that may exclude these groups are modified to accommodate them equally

Waste Management - Innovative Solutions for African Municipalities

The management of solid waste in developing countries is an emerging critical issue. With consumption rising in developing areas of the world, and urbanisation continuing at a rapid pace, the sustainable management of waste and re-utilisation of waste as a resource are both important challenges and research areas in the development sphere. This policy brief, produced by the DFID/DECC/EPSRC-funded SAMSET (Supporting African Municipalities in Sustainable Energy Transitions) Project, aims to address the main issues surrounding the sustainable management of municipal waste, and propose elements of policy recommendations and local-government-level solutions for improving the sustainability of urban waste management. This policy brief focuses on Sub-Saharan African contexts, where rapid urbanisation is arguably posing the greatest challenges, but offers cross-cutting lessons and best practices for urban waste management in a number of developing country contexts

Gender and Inclusive Urbanisation

Traditional urban planning practices for urban development in the developing world often fail to take into account the specific ways in which decisions on a policy level, as well as in implementation, can disadvantage women and girls in urban areas. The dimensions of gender in urban planning are an area that has been underrepresented in the literature on urban planning practices, although in the last decade some attention has been given on how to tailor urban planning practices to be more inclusive across genders. Women can be adversely affected by urban planning in a number of ways, both physical and socio-political. Transport access, access to sanitation and water, and access to clean energy are all areas where traditional methods of urban planning for development leave women and girls at a disadvantage

Argenton-sur-Creuse – Ancien cimetière de l’église Saint-Étienne

Date de l'opération : 1991 (SU) Inventeur(s) : Lemaire D Plusieurs observations ont été réalisées aux abords de l'église Saint-Etienne afin d'évaluer la profondeur d'enfouissement des sépultures avant le réaménagement du parvis et de la place Voltaire. Dans une tranchée creusée à une soixantaine de mètres au nord de l'église, la présence d'une sépulture en place témoigne de la grande extension du cimetière à une époque cependant indéterminée. Un mur, dont les fondations ont été dégagées, peut..