18 resultados para duality

em Aston University Research Archive


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We study electronic transport in a Luttinger liquid with an embedded impurity, which is either a weak scatterer (WS) or a weak link (WL), when interacting electrons are coupled to one-dimensional massless bosons (e.g., acoustic phonons). We find that the duality relation, ?WS?WL=1, between scaling dimensions of the electron backscattering in the WS and WL limits, established for the standard Luttinger liquid, holds in the presence of the additional coupling for an arbitrary fixed strength of boson scattering from the impurity. This means that at low temperatures such a system remains either an ideal insulator or an ideal metal, regardless of the scattering strength. On the other hand, when fermion and boson scattering from the impurity are correlated, the system has a rich phase diagram that includes a metal-insulator transition at some intermediate values of the scattering.

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We study a Luttinger liquid (LL) coupled to a generic environment consisting of bosonic modes with arbitrary density-density and current-current interactions. The LL can be either in the conducting phase and perturbed by a weak scatterer or in the insulating phase and perturbed by a weak link. The environment modes can also be scattered by the imperfection in the system with arbitrary transmission and reflection amplitudes. We present a general method of calculating correlation functions under the presence of the environment and prove the duality of exponents describing the scaling of the weak scatterer and of the weak link. This duality holds true for a broad class of models and is sensitive to neither interaction nor environmental modes details, thus it shows up as the universal property. It ensures that the environment cannot generate new stable fixed points of the renormalization group flow. Thus, the LL always flows toward either conducting or insulating phase. Phases are separated by a sharp boundary which is shifted by the influence of the environment. Our results are relevant, for example, for low-energy transport in (i) an interacting quantum wire or a carbon nanotube where the electrons are coupled to the acoustic phonons scattered by the lattice defect; (ii) a mixture of interacting fermionic and bosonic cold atoms where the bosonic modes are scattered due to an abrupt local change of the interaction; (iii) mesoscopic electric circuits.

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We have devised a general scheme that reveals multiple duality relations valid for all multi-channel Luttinger Liquids. The relations are universal and should be used for establishing phase diagrams and searching for new non-trivial phases in low-dimensional strongly correlated systems. The technique developed provides universal correspondence between scaling dimensions of local perturbations in different phases. These multiple relations between scaling dimensions lead to a connection between different inter-phase boundaries on the phase diagram. The dualities, in particular, constrain phase diagram and allow predictions of emergence and observation of new phases without explicit model-dependent calculations. As an example, we demonstrate the impossibility of non-trivial phase existence for fermions coupled to phonons in one dimension. © 2013 EPLA.

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The title of Juana Castro’s poetry book publshed in 1978, Cóncava mujer — Concave woman — expresses the hollow nature of the social female subject. From Juana Castro’s point of view, this female social concavity is only allowed to transformed itself into its opposite, the convex women which clearly represents the reproductive role of the female body. These two extreme roles assigned to women, hollowness or maternity, are the poetic paradigms for Juana Castro’s two poetry books analised in this article. As if we were presented with the two sides of a coin, Cóncava mujer and Del dolor y las alas – On anguish and wings--(1982) reflect the author´s concious realisation of the above-mentioned female duality as a defined and percieved subject by male society. Each poetry book, however, respond to two different personal moments, and each result in two different ways of conceiving poetic language. On one hand, the poetic subject of Cóncava mujer emerges with all its force as a feminist voice whose goal is the attack of all aspects of the patriarchal society as the cause of the female concavity. On the other hand, in Del dolor y las alas the poetic voice unfolds her motherhood as both loss and creation: the death of Juana Castro’s son makes the poetic subject incomplete, and therefore a concave one; whereas the poetic discourse appears as the perfect way to occupy the empty space left by the son’s death.

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The organization of linguistic meaning is animated by the duality between the sense of signs and the reference to the experience of speakers. How the presuppositions communicated by speakers emanate from the conventional value of signs and their cotextual dependencies is explored in this monograph on the scope and focus of negation. Negation can have scope over the predicate of the sequence in which it is used. The body of data brought together show that a variety of configurations preclude command of the predicate by the negative scoping over it, and that scope is a semantic rather than structural relation. Scope defines the domain in which an item can be focused by negation. Negative focus is dependent on the evocation of an alternative value, which may be generated by lexical antonymy, syntactic determination or contextual corrections. The study of focus and scope of negation on the basis of attested examples from different varieties of French demonstrates how the independently motivated semantic principles of relation to predicate and reference to an alternative value account for the observed effects.

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This article approaches the fragmentation of identities characteristic of contemporary Western societies through the 1992 film Léolo by Jean-Claude Lauzon. Although it does explore linguistic, social, religious and ethnic divisions, this major piece of the Quebec repertoire recasts the sociolinguistic conflict between vernacular and formal practices (Labov 1972; Blanche-Benveniste 2002), raising questions of status and choice. This conflict is subsumed by the dialectics between primary and secondary culture. The cultural and linguistic opposition finds a primary metaphor in the film's central motif of the duality of dream and reality. No more than the cultural and linguistic can this opposition find a synthesis. This impossible reconciliation defines the constitutive rupture of the human psyche itself.

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Outcomes measures, which is the measurement of effectiveness of interventions and services has been propelled onto the health service agenda since the introduction of the internal market in the 1990s. It arose as a result of the escalating cost of inpatient care, the need to identify what interventions work and in what situations, and the desire for effective information by service users enabled by the consumerist agenda introduced by Working for Patients white paper. The research reported in this thesis is an assessment of the readiness of the forensic mental health service to measure outcomes of interventions. The research examines the type, prevalence and scope of use of outcomes measures, and further seeks a consensus of views of key stakeholders on the priority areas for future development. It discusses the theoretical basis for defining health and advocates the argument that the present focus on measuring effectiveness of care is misdirected without the input of users, particularly patients in their care, drawing together the views of the many stakeholders who have an interest in the provision of care in the service. The research further draws on the theory of structuration to demonstrate the degree to which a duality of action, which is necessary for the development, and use of outcomes measures is in place within the service. Consequently, it highlights some of the hurdles that need to be surmounted before effective measurement of health gain can be developed in the field of study. It concludes by advancing the view that outcomes research can enable practitioners to better understand the relationship between the illness of the patient and the efficacy of treatment. This understanding it is argued would contribute to improving dialogue between the health care practitioner and the patient, and further providing the information necessary for moving away from untested assumptions, which are numerous in the field about the superiority of one treatment approach over another.

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This study is an examination of the timeliness of corporate internet reporting by U.K. companies listed on the London Stock Exchange (LSE). The research examines the significance of several corporate governance and firm-specific characteristics as potential determinants of the timeliness of corporate internet reporting. Our primary analysis provides evidence of a significant association between timely corporate internet reporting and the corporate governance characteristics of board experience and board independence. Our findings provide evidence that boards with less cross directorships, more experience in terms of the average age of directors, and lower length in service for executive directors provide more timely corporate internet reporting.We find that board independence is negatively associated with timely corporate internet reporting. Follow-up analysis provides additional evidence of a significant association between the timeliness of corporate internet reporting and board experience. The evidence indicates that role duality and block ownership are associated with less timely corporate internet reporting. Our findings also reveal strengths and weaknesses in the Internet reporting of U.K. listed companies. Companies need to voluntarily focus on improving the timeliness dimension of their corporate internet reporting so that the EU and U.K. accounting regulators do not replace recommendations with regulations.

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This paper contributes to extend the minimax disparity to determine the ordered weighted averaging (OWA) model based on linear programming. It introduces the minimax disparity approach between any distinct pairs of the weights and uses the duality of linear programming to prove the feasibility of the extended OWA operator weights model. The paper finishes with an open problem. © 2006 Elsevier Ltd. All rights reserved.

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This research examines the role of the information management process within a process-oriented enterprise, Xerox Ltd. The research approach is based on a post-positive paradigm and has resulted in thirty-five idiographic statements. The three major outcomes are: 1. The process-oriented holistic enterprise is an organisation that requires a long-term management commitment to its development. It depends on the careful management of people, tasks, information and technology. A complex integration of business processes is required and this can be managed through the use of consistent documentation techniques, clarity in the definition of process responsibilities and management attention to the global metrics and the centralisation of the management of the process model are critical to its success. 2. The role of the information management process within the context of a process-oriented enterprise is to provide flexible and cost-effective applications, technological, and process support to the business. This is best achieved through a centralisation of the management of information management and of the process model. A business-led approach combined with the consolidation of applications, information, process, and data architectures is central to providing effective business and process-focused support. 3. In a process oriented holistic enterprise, process and information management are inextricably linked. The model of process management depends heavily on information management, whilst the model of information management is totally focused around supporting and creating the process model. The two models are mutually creating - one cannot exist without the other. There is a duality concept of process and information management.

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Despite the voluminous studies written about organisational innovation over the last 30-40 years our understanding of this phenomenon continues to be inconsistent and inconclusive (Wolfe, 1994). An assessment of the theoretical and methodological issues influencing the explanatory utility of many studies has led scholars (e.g. Slappendel, 1996) to re-evaluate the assumptions used to ground studies. Building on these criticisms the current study contributes to the development of an interactive perspective of organisational innovation. This work contributes empirically and theoretically to an improved understanding of the innovation process and the interaction between the realm of action and the mediating effects of pre-existing contingencies i.e. social control, economic exchange and the communicability of knowledge (Scarbrough, 1996). Building on recent advances in institutional theory (see Barley, 1986; 1990; Barley and Tolbert, 1997) and critical theory (Morrow, 1994, Sayer, 1992) the study aims to demonstrate, via longitudinal intensive research, the process through which ideas are translated into reality. This is significant because, despite a growing recognition of the implicit link between the strategic conduct of actors and the institutional realm in organisational analysis, there are few examples that theorise and empirically test these connections. By assessing an under researched example of technology transfer; the government's Teaching Company Scheme (TCS) this project provides a critique of the innovation process that contributes to theory and our appreciation of change in the UK government's premier technology transfer scheme (QR, 1996). Critical moments during the translation of ideas illustrate how elements that are linked to social control, economic exchange and communicability mediate the innovation process. Using analytical categories i.e. contradiction, slippage and dysfunctionality these are assessed in relation to the actions (coping strategies) of programme members over a two-year period. Drawing on Giddens' (1995) notion of the duality of structure this study explores the nature of the relationship between the task environment and institutional environment demonstrating how and why knowledge is both an enabler and barrier to organisational innovation.

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By applying narrative theory to the party political texts emerging within the UK Labour Party after 2010, which make up the corpus of One Nation discourse, we can grasp the underlying significance of this ideational revision of Labour Party and leftist thought. Through an identification and analysis of the sequence of texts and their constitution as a "story" that interpolates an underlying "plot," we can see how a revision of Labour's "tale" offers to leadership a new party discourse appropriate to it, mediating-if not reconciling-the problematic duality of narrative authorship by both party and leader. © The Political Quarterly Publishing Co. Ltd. 2013.

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Recent changes in the regulatory environment of the London Stock Exchange are aimed at prohibiting selective disclosure and enhancing the credibility of reporting. Using an innovative 143-item disclosure checklist, we examine corporate Internet reporting (CIR) comprehensiveness and its determinants within this new regulatory environment. We also extend the literature linking corporate governance measures to CIR. Our findings indicate that despite this new regulatory environment, there is considerable room for improvement in CIR by London-listed companies. For example, our sample companies provide only 58 percent and 70 percent, respectively, of the credibility and usability items assessed by our comprehensiveness index. After controlling for size, profitability, industry, and high growth/ intangibles, we find the CIR comprehensiveness of London-listed companies is associated with analyst following, director holding, director independence, and CEO duality. Because prior research indicates the U.K. leads Europe in Internet reporting, our results may shed light on how CIR will evolve throughout Europe.

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This study is an examination of the timeliness of corporate internet reporting by U.K. companies listed on the London Stock Exchange (LSE). The research examines the significance of several corporate governance and firm-specific characteristics as potential determinants of the timeliness of corporate internet reporting. Our primary analysis provides evidence of a significant association between timely corporate internet reporting and the corporate governance characteristics of board experience and board independence. Our findings provide evidence that boards with less cross directorships, more experience in terms of the average age of directors, and lower length in service for executive directors provide more timely corporate internet reporting. We find that board independence is negatively associated with timely corporate internet reporting. Follow-up analysis provides additional evidence of a significant association between the timeliness of corporate internet reporting and board experience. The evidence indicates that role duality and block ownership are associated with less timely corporate internet reporting. Our findings also reveal strengths and weaknesses in the Internet reporting of U.K. listed companies. Companies need to voluntarily focus on improving the timeliness dimension of their corporate internet reporting so that the EU and U.K. accounting regulators do not replace recommendations with regulations. © 2007 Elsevier Inc. All rights reserved.

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This article reflects on context effects in the study of behavioral ethics and organizational justice. After a general overview, we review three key challenges confronting research in these two domains. First, we consider social scientific versus normative approaches to inquiry. The former aims for a scientific description, while the latter aims to provide prescriptive advice for moral conduct. We argue that the social scientific view can be enriched by considering normative paradigms. The next challenge we consider, involves the duality of morally upright versus morally inappropriate behavior. We observe that there is a long tradition of categorizing behavior dichotomously (e.g., good vs. bad) rather than continuously. We conclude by observing that more research is needed to compare the dichotomous versus continuous perspectives. Third, we examine the role of “cold” cognitions and “hot” affect in making judgments of ethicality. Historically speaking, research has empathized cognition, though recent work has begun to add greater balance to affective reactions. We argue that both cognition and affect are important, but more research is needed to determine how they work together. After considering these three challenges, we then turn to our special issue, providing short reviews of each contribution and how they help in better addressing the three challenges we have identified.