Structural changes in quasi-one-dimensional many-electron systems: From linear to zigzag and beyond

Many-electron systems confined to a quasi-one-dimensional geometry by a cylindrical distribution of positive charge have been investigated by density functional computations in the unrestricted local spin density approximation. Our investigations have been focused on the low-density regime, in which electrons are localized. The results reveal a wide variety of different charge and spin configurations, including linear and zig-zag chains, single-and double-strand helices, and twisted chains of dimers. The spin-spin coupling turns from weakly antiferromagnetic at relatively high density, to weakly ferromagnetic at the lowest densities considered in our computations. The stability of linear chains of localized charge has been investigated by analyzing the radial dependence of the self-consistent potential and by computing the dispersion relation of low-energy harmonic excitations.

Dublin docklands. The urban fabric as cultural heritage

Introduction

Since the 1980s there have been major policies and projects for the redevelopment of Dublin Docklands. These projects were mainly aimed at profitable development of office, commercial and residential space, without a sound plan that would preserve the identity or community of the area. The recent shift in policies and urban design principles in the Dublin Docklands Area Master Plan 2008 shows that policy makers have acknowledged that mistakes were made in the last decades of the 20th century. The current map of the Dublin Docklands Area Master Plan 2008 gives us useful information about these changes. The Ringsend/ Irishtown area, which has kept a great part of its urban form and community identity throughout centuries, is described as an ‘area of protection of residential and services amenities’ (DDDA, 2008, map A). Meanwhile, the area of the Grand Canal Docks, recently developed, is described with the objective ‘to seek the social, economic and physical development or rejuvenation
within an area of mixed use of which residential and enterprise facilities would be the predominant uses’ (DDDA, 2008, map A). This classification shows that recent development has been unable to achieve the cohesion and complexity of existing neighbourhoods, revealing flaws not only in policy, but also in the built environment and approaches to urban design.

The shift towards the consideration of more community participation reveals a need to understand the tradition and past of these communities, while the urban fabric of small plots in the existing neighbourhoods, therefore, seems to have a very important role in the conservation of identity of place and providing the opportunity for difference within regularity. On the other hand, the new fabric of residential block developments in the docklands denies the possibility of developing a sense of community, and by providing only regularity, does not leave space for difference.

This paper will address questions related to urban morphology and town analysis in the case of Ringsend and Irishtown. This will provide a tool to learn from the past and perhaps find new models of development that might be less detrimental for the heritage of cities and urban communities. One of the ideas of this paper is to adhere to the new tendency in conservation policies to provide a broader analysis of urban areas, not only considering individual monuments in cities, but also analysing the significance of urban morphology and intangible heritage. It forms part of an OPW Post- Doctoral Fellowship in Conservation Studies and Environmental History.1 Research has been carried out in different areas of urban history of Dublin’s southern waterfront, including infrastructure history and a thorough analysis of the letters of the Pembroke Estate of the 19th century, which included the areas of Ringsend and Irishtown. However, this paper focuses on the study of urban form of the area and its significance to Dublin’s heritage.

Waterfront retrieved. Buenos Aires’ contrasting leisure experience

The southern waterfront of the city of Buenos Aires has been recovered. Now that more than 20 years have passed since the projects began, we are able to get some perspective on these developments and can confront them with the integral history of this area. The areas of Puerto Madero, Costanera Sur, Reserva Ecológica and Santa María del Plata have distinctive characteristics and these are reflected in urban landscape, architecture and especially through the use of these spaces. Real estate developments cohabit with public space, tourism with local leisure facilities, and the most expensive office floors with local choripan1 stands, all of these in a development in which the state, the municipality, international corporations and real estate companies have collaborated and discussed to produce a hybrid new space for the city.