2,685 research outputs found

    Fermionization, Convergent Perturbation Theory, and Correlations in the Yang-Mills Quantum Field Theory in Four Dimensions

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    We show that the Yang-Mills quantum field theory with momentum and spacetime cutoffs in four Euclidean dimensions is equivalent, term by term in an appropriately resummed perturbation theory, to a Fermionic theory with nonlocal interaction terms. When a further momentum cutoff is imposed, this Fermionic theory has a convergent perturbation expansion. To zeroth order in this perturbation expansion, the correlation function E(x,y)E(x,y) of generic components of pairs of connections is given by an explicit, finite-dimensional integral formula, which we conjecture will behave as E(x,y)∼∣x−y∣−2−2dG,E(x,y) \sim |x - y|^{-2 - 2 d_G}, \noindent for ∣x−y∣>>0,|x-y|>>0, where dGd_G is a positive integer depending on the gauge group G.G. In the case where G=SU(n),G=SU(n), we conjecture that dG=dimSU(n)−dimS(U(n−1)×U(1)),d_G = {\rm dim}SU(n) - {\rm dim}S(U(n-1) \times U(1)), \noindent so that the rate of decay of correlations increases as n→∞.n \to \infty.Comment: Minor corrections of notation, style and arithmetic errors; correction of minor gap in the proof of Proposition 1.4 (the statement of the Proposition was correct); further remark and references adde

    Supporting memory and identity in older people: findings from a ‘Sandpit’ process

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    Identity in old age is challenged by physical changes, evolving roles within the family, and life transitions such as retirement. Supporting identity is therefore important in later life, and might be assisted by media technologies which allow people to reflect on their lives, record their personal histories and share these with family, friends and caregivers. This possibility was explored in two creative ‘Sandpits’ with older people as part of the SUS-IT project, funded by the New Dynamics of Ageing programme in the UK. Discussions were held with PC and non-PC user groups of retirement age to understand memory and identity practices and elicit reactions to three novel product concepts. These included a Reminiscing Radio for life review, a Story Lamp for associating spoken stories with photographs and memorabilia, and a pair of virtual reality Travel Glasses for transporting you back to a special place in the past. The main findings of these discussions will be presented, along with concepts generated by the participants in a re-design exercise. This paper will also show how the sandpits enabled older people to be involved in the design process by allowing them to shape early design concepts through exploring their own ideas and motivations

    Unlocking Opportunity for African American Girls: A Call to Action for Educational Equity

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    This report seeks to expand conversations around educational opportunity by taking a comprehensive look at the barriers African American girls face and the educational and economic outcomes that result. One important barrier is the prevalence of stereotypes that adversely impact the educational experiences of African American girls. Structural and institutional barriers examined in this report -- such as under-resourced schools, disparate discipline practices, gender-based violence and harassment, and lack of support for pregnant and parenting students -- further compromise educational outcomes for African American girls. This report fills an important gap in existing data on educational achievement and its attendant economic consequences. Although there is plentiful data on American children and education, the lack of data broken down by race and gender together has fueled the assumption that all girls are doing fine in school. But in fact, although girls overall graduate from high school at higher rates than boys, girls of color are graduating at far lower rates than white girls and boys. In almost all states with available data, the high school graduation rate for African American girls is below the national average for girls overall, resulting in severe economic consequences for African American women and their families

    Family memories in the home: contrasting physical and digital mementos

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    We carried out fieldwork to characterise and compare physical and digital mementos in the home. Physical mementos are highly valued, heterogeneous and support different types of recollection. Contrary to expectations, we found physical mementos are not purely representational, and can involve appropriating common objects and more idiosyncratic forms. In contrast, digital mementos were initially perceived as less valuable, although participants later reconsidered this. Digital mementos were somewhat limited in function and expression, largely involving representational photos and videos, and infrequently accessed. We explain these digital limitations and conclude with design guidelines for digital mementos, including better techniques for accessing and integrating these into everyday life, allowing them to acquire the symbolic associations and lasting value that characterise their physical counterparts

    Coherent phenomena in mesoscopic systems

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    A mesoscopic system of cylindrical geometry made of a metal or a semiconductor is shown to exhibit features of a quantum coherent state. It is shown that magnetostatic interaction can play an important role in mesoscopic systems leading to an ordered ground state. The temperature T∗T^{*} below the system exhibits long-range order is determined. The self-consistent mean field approximation of the magnetostatic interaction is performed giving the effective Hamiltonian from which the self-sustaining currents can be obtained. The relation of quantum coherent state in mesoscopic cylinders to other coherent systems like superconductors is discussed.Comment: REVTeX, 4 figures, in print in Supercond. Sci. Techno

    The challenge of designing for diversity in older users

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    Purpose: The older population is not a homogenous group and show significant diversity in constitution, capabilities and experience. In order for new and emerging digital technologies to be inclusive, it is crucial to encompass this diversity and employ a design process that is sensitive to it. Current approaches to inclusive design tend to seek one design for all, focusing on users who are least engaged with digital technology. In this paper we outline an alternative approach to inclusive design based on co-design with both digitally engaged and unengaged user groups. In our study, as part of a multi-disciplinary group in the New Dynamics of Ageing (UK) funded collaborative research project, older people from different walks of life were invited to four different themed workshops called ‘sandpits’ to explore current and emerging technologies in a playful and creative context to help them envisage the potential implications these technologies can have in their lives as well as to identify key issues and user requirements for further development. This paper will discuss the outcome from three of those sandpits. The themes explored in these three sandpits were 1) Custom computers for older people 2) Supporting Identity and memory in later life and 3) Social connections with new technology. Methods. A total of 66 older people participated in the three sandpits conducted between 2009 and 2010. Separated into PC and non-PC users groups, they were involved in discussions and shown open ambiguous envisionments that responded to the themes through hands-on demonstration, role-play or dramatic enactment of their use. Broadly taking into account the role of technology generations effects, the envisionments were modeled and presented as appliances, incorporating forms of products and interactions that older people are familiar with to encourage in-clusion. The older participants were then involved in the redesign of these envisionments through a collaborative design process. Results and discussion The design responses from older PC and non-PC user groups revealed a difference in the type of embodiment they want for Internet-enabled applications. Both groups redesigned the concepts based on their experience, interests, familiarity with the technology they have and its associated infrastructure or lack thereof. In general, non-PC user groups preferred the appliance nature of the envisionments, and incorporated the functions they were interested in performing, such as capturing spoken stories, sharing photographs, chatting over TV programmes, etc into these appliances. In contrast, PC owners questioned the need for separate appliances and often re-designed them as PC applications or Internet services with emphasis placed on modality and compatibility with their existing infrastructure. The paper will discuss the difficulty and challenge of bridging the gap between the diversity of technology and its users

    Variability in Quantity and Composition of Water Soluble Carbohydrates Among Irish Accessions and European Varieties of Perennial Ryegrass

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    The objective of this study was to identify perennial ryegrass accessions displaying high fructose and glucose contents and an improved ratio between fructose and glucose fractions across different time points throughout the year. Fructose and glucose are the main constituents of the water soluble carbohydrate (WSC) fraction in perennial ryegrass. For animal nutrition the amount of WSC is crucial as it is the primary energy source available to metabolise the intake of plant protein. The ratio between fructose and glucose fractions is important since fructosan chains, which are an excellent energy source for ruminants, are built from fructose. Furthermore the seasonal variability of WSC content in feed reflects the changing balance between protein and carbohydrates

    Biodiversity studies of fungi on monocotyledonous plants in the tropics

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    Abstractpublished_or_final_versionThe Joint Annual Meeting of the Mycological Society of America and the American Bryological and Lichenological Society, San Juan, Puerto Rico, USA, 11-16 June 1998, In Inoculum, 1998, v. 49 n. 2, p. 2

    Variability in Quantity and Composition of Water Soluble Carbohydrates Among Irish Accessions and European Varieties of Perennial Ryegrass

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    The objective of this study was to identify perennial ryegrass accessions displaying high fructose and glucose contents and an improved ratio between fructose and glucose fractions across different time points throughout the year. Fructose and glucose are the main constituents of the water soluble carbohydrate (WSC) fraction in perennial ryegrass. For animal nutrition the amount of WSC is crucial as it is the primary energy source available to metabolise the intake of plant protein. The ratio between fructose and glucose fractions is important since fructosan chains, which are an excellent energy source for ruminants, are built from fructose. Furthermore the seasonal variability of WSC content in feed reflects the changing balance between protein and carbohydrates
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