123 research outputs found

    de Sitter symmetry of Neveu-Schwarz spinors

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    We study the relations between Dirac fields living on the 2-dimensional Lorentzian cylinder and the ones living on the double-covering of the 2-dimensional de Sitter manifold, here identified as a certain coset space of the group SL(2,R)SL(2,R). We show that there is an extended notion of de Sitter covariance only for Dirac fields having the Neveu-Schwarz anti-periodicity and construct the relevant cocycle. Finally, we show that the de Sitter symmetry is naturally inherited by the Neveu-Schwarz massless Dirac field on the cylinder.Comment: 24 page

    Brick Walls and AdS/CFT

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    We discuss the relationship between the bulk-boundary correspondence in Rehren's algebraic holography (and in other 'fixed-background' approaches to holography) and in mainstream 'Maldacena AdS/CFT'. Especially, we contrast the understanding of black-hole entropy from the viewpoint of QFT in curved spacetime -- in the framework of 't Hooft's 'brick wall' model -- with the understanding based on Maldacena AdS/CFT. We show that the brick-wall modification of a Klein Gordon field in the Hartle-Hawking-Israel state on 1+2-Schwarzschild AdS (BTZ) has a well-defined boundary limit with the same temperature and entropy as the brick-wall-modified bulk theory. One of our main purposes is to point out a close connection, for general AdS/CFT situations, between the puzzle raised by Arnsdorf and Smolin regarding the relationship between Rehren's algebraic holography and mainstream AdS/CFT and the puzzle embodied in the 'correspondence principle' proposed by Mukohyama and Israel in their work on the brick-wall approach to black hole entropy. Working on the assumption that similar results will hold for bulk QFT other than the Klein Gordon field and for Schwarzschild AdS in other dimensions, and recalling the first author's proposed resolution to the Mukohyama-Israel puzzle based on his 'matter-gravity entanglement hypothesis', we argue that, in Maldacena AdS/CFT, the algebra of the boundary CFT is isomorphic only to a proper subalgebra of the bulk algebra, albeit (at non-zero temperature) the (GNS) Hilbert spaces of bulk and boundary theories are still the 'same' -- the total bulk state being pure, while the boundary state is mixed (thermal). We also argue from the finiteness of its boundary (and hence, on our assumptions, also bulk) entropy at finite temperature, that the Rehren dual of the Maldacena boundary CFT cannot itself be a QFT and must, instead, presumably be something like a string theory.Comment: 54 pages, 3 figures. Arguments strengthened in the light of B.S. Kay `Instability of Enclosed Horizons' arXiv:1310.739

    Yang-Mills instantons and dyons on homogeneous G_2-manifolds

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    We consider Lie G-valued Yang-Mills fields on the space R x G/H, where G/H is a compact nearly K"ahler six-dimensional homogeneous space, and the manifold R x G/H carries a G_2-structure. After imposing a general G-invariance condition, Yang-Mills theory with torsion on R x G/H is reduced to Newtonian mechanics of a particle moving in R^6, R^4 or R^2 under the influence of an inverted double-well-type potential for the cases G/H = SU(3)/U(1)xU(1), Sp(2)/Sp(1)xU(1) or G_2/SU(3), respectively. We analyze all critical points and present analytical and numerical kink- and bounce-type solutions, which yield G-invariant instanton configurations on those cosets. Periodic solutions on S^1 x G/H and dyons on iR x G/H are also given.Comment: 1+26 pages, 14 figures, 6 miniplot

    Development and preliminary validation of a Greek-language outpatient satisfaction questionnaire with principal components and multi-trait analyses

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    BACKGROUND: In the recent years there is a growing interest in Greece concerning the measurement of the satisfaction of patients who are visiting the outpatient clinics of National Health System (NHS) general acute hospitals. The aim of this study is therefore to develop a patient satisfaction questionnaire and provide its preliminary validation. METHODS: A questionnaire in Greek has been developed by literature review, researchers' on the spot observation and interviews. Pretesting has been followed by telephone surveys in two short-term general NHS hospitals in Macedonia, Greece. A proportional stratified random sample of 285 subjects and a second random sample of 100 outpatients, drawn on March 2004, have been employed for the analysis. These have resulted in scale creation via Principal Components Analysis and psychometric testing for internal consistency, test-retest and interrater reliability as well as construct validity. RESULTS: Four summated scales have emerged regarding the pure outpatient component of the patients' visits, namely medical examination, hospital environment, comfort and appointment time. Cronbach's alpha coefficients and Pearson, Spearman and intraclass correlations indicate a high degree of scale reliability and validity. Two other scales -lab appointment time and lab experience- capture the apparently distinct yet complementary visitor experience related to the radiographic and laboratory tests. Psychometric tests are equally promising, however, some discriminant validity differences lack statistical significance. CONCLUSION: The instrument appears to be reliable and valid regarding the pure outpatient experience, whereas more research employing larger samples is required in order to establish the apparent psychometric properties of the complementary radiographic and laboratory-testing process, which is only relevant to about 25% of the subjects analysed here

    Critical views on postpartum care expressed by new mothers

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    <p>Abstract</p> <p>Background</p> <p>Women's evaluation of hospital postpartum care has consistently been more negative than their assessment of other types of maternity care. The need to further explore what is wrong with postpartum care, in order to stimulate changes and improvements, has been stressed. The principal aim of this study was to describe women's negative experiences of hospital postpartum care, expressed in their own words. Characteristics of the women who spontaneously gave negative comments about postpartum care were compared with those who did not.</p> <p>Methods</p> <p>Data were taken from a population-based prospective longitudinal study of 2783 Swedish-speaking women surveyed at three time points: in early pregnancy, at two months, and at one year postpartum. At the end of the two follow-up questionnaires, women were asked to add any comment they wished. Content analysis of their statements was performed.</p> <p>Results</p> <p>Altogether 150 women gave negative comments about postpartum care, and this sample was largely representative of the total population-based cohort. The women gave a diverse and detailed description of their experiences, for instance about lack of opportunity to rest and recover, difficulty in getting individualised information and breastfeeding support, and appropriate symptom management. The different statements were summarised in six categories: organisation and environment, staff attitudes and behaviour, breastfeeding support, information, the role of the father and attention to the mother.</p> <p>Conclusion</p> <p>The findings of this study underline the need to further discuss and specify the aims of postpartum care. The challenge of providing high-quality follow-up after childbirth is discussed in the light of a development characterised by a continuous reduction in the length of hospital stay, in combination with increasing public demands for information and individualised care.</p

    A multilevel investigation of inequalities in clinical and psychosocial outcomes for women after breast cancer

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    Background In Australia, breast cancer is the most common cancer affecting Australian women. Inequalities in clinical and psychosocial outcomes have existed for some time, affecting particularly women from rural areas and from areas of disadvantage. We have a limited understanding of how individual and area-level factors are related to each other, and their associations with survival and other clinical and psychosocial outcomes. Methods/Design This study will examine associations between breast cancer recurrence, survival and psychosocial outcomes (e.g. distress, unmet supportive care needs, quality of life). The study will use an innovative multilevel approach using area-level factors simultaneously with detailed individual-level factors to assess the relative importance of remoteness, socioeconomic and demographic factors, diagnostic and treatment pathways and processes, and supportive care utilization to clinical and psychosocial outcomes. The study will use telephone and self-administered questionnaires to collect individual-level data from approximately 3, 300 women ascertained from the Queensland Cancer Registry diagnosed with invasive breast cancer residing in 478 Statistical Local Areas Queensland in 2011 and 2012. Area-level data will be sourced from the Australian Bureau of Statistics census data. Geo-coding and spatial technology will be used to calculate road travel distances from patients' residence to diagnostic and treatment centres. Data analysis will include a combination of standard empirical procedures and multilevel modelling. Discussion The study will address the critical question of: what are the individual- or area-level factors associated with inequalities in outcomes from breast cancer? The findings will provide health care providers and policy makers with targeted information to improve the management of women with breast cancer, and inform the development of strategies to improve psychosocial care for women with breast cancer

    The patient experience

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    The impact of improved treatments for the management of hormone-sensitive breast cancer extends beyond clinical responses. Thanks to appropriate literature and access to the internet, patient awareness of treatment options has grown and patients are now, in many cases, able to engage their oncologists in informed conversations regarding treatment and what to expect in terms of efficacy and safety. Indeed, patients realize that although there is no cure for metastatic disease, treatment can greatly reduce the risk of progression and in the adjuvant setting, where treatment is administered with a curative intent, current treatment options reduce the risk of relapse. The approval of letrozole throughout the breast cancer continuum has provided patients with many reassuring options. The improvement in outcome with letrozole is achieved without a detrimental effect on overall quality of life. Adverse events such as hot flushes, arthralgia, vaginal dryness, and potential osteoporosis are most significant from the patient’s perspective, and it is important that caregivers pay attention to patients experiencing these events, as they can impact compliance unless effectively explained and managed. The major benefits of letrozole are to improve prospects for long-term survivorship in the adjuvant setting and to delay progression and the need for chemotherapy in the metastatic setting
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