Noncommuting Electric Fields and Algebraic Consistency in Noncommutative Gauge theories

We show that noncommuting electric fields occur naturally in $\theta$-expanded noncommutative gauge theories. Using this noncommutativity, which is field dependent, and a hamiltonian generalisation of the Seiberg-Witten Map, the algebraic consistency in the lagrangian and hamiltonian formulations of these theories, is established. A comparison of results in different descriptions shows that this generalised map acts as canonical transformation in the physical subspace only. Finally, we apply the hamiltonian formulation to derive the gauge symmetries of the action.Comment: 16 pages, LaTex, considerably expanded version with a new section on `Gauge symmetries'; To appear in Phys. Rev.

'Just Little Things': Nurses' perceptions of quality of life for people with severe multiple impairments.

ABSTRACT Notions of quality of life dictate philosophies and policies for services for people with developmental disabilities. There is an abundance of research on quality of life, much of which has influenced the significant amount of study of quality of life for people with developmental disabilities. According to specialist developmental disability nurses, however, this research has little meaning for one group of people with developmental disabilities with whom they work - people with severe multiple impairments. Nevertheless, judgements and decisions about the lives of this group continue to be driven by the idea of quality of life. While the literature review found that researchers are urged to seek the perceptions of people regarding their own quality of life by asking them, some authors have noted the difficulty in pursuing such a method with people, such as people with severe multiple impairments, who are unable to communicate in the usual ways. Given, then, that it is difficult to directly determine the views of people with severe multiple impairments, this study sought the perceptions of nurses about the quality of life of the people with whom they work. In order to discover and conceptualise nurses' views, a symbolic interaction perspective was chosen to guide this study and data were analysed using the grounded theory approach. The study was conducted in two stages. Stage One consisted of semi-structured indepth interviews with expert nurses to explore their perceptions of quality of life for the people with whom they worked. A significant finding in these interviews was that perceptions of quality of life are mediated by interaction. Consequently, Stage Two involved a participant observation study in which the interactions of nurses and people with severe multiple impairments were examined. Specialist developmental disability nurses have a unique view of quality of life for people with severe multiple impairments. They refer to it as 'just little things', a phrase which masks complex nursing knowledge and skills, and which can be described by four interrelated categories which emerged from the data: humans being, supporting, becoming intimate, and situated belonging. As nurses become more intimate with individuals, they perceive that people with severe multiple impairments are humans being as they wish, and that quality resides in supporting their everyday lives in a context of situated belonging. This thesis represents a new conceptualisation of quality of life for people with severe multiple impairments, a conceptualisation which may have significance for other groups and, indeed, for the whole quality of life enterprise. This conceptualisation draws on knowledge not usually related to quality of life, that is, knowledge of the body, of the emotions, of identity and of humanness. Such findings demonstrate the power of an interpretive approach in explicating the meanings nurses have regarding quality of life. Further, these findings have implications for how the question of quality of life is approached, for how different ways of thinking about people impact on quality of life, and for the importance of the life in quality of life

Energetics and stability of vacancies in carbon nanotubes

In this work we present ab initio calculations of the formation energies and stability of different types of multi-vacancies in carbon nanotubes. We demonstrate that, as in the case of graphene, the reconstruction of the defects has drastic effects on the energetics of the tubes. In particular, the formation of pentagons eliminates the dangling bonds thus lowering the formation energy. This competition leads to vacancies having an even number of carbon atoms removed to be more stable. Finally the appearance of magic numbers indicating more stable defects can be represented by a model for the formation energies that is based on the number of dangling bonds of the unreconstructed system, the pentagons and the relaxation of the final form of the defect formed after the relaxation