418 research outputs found

    Coexistence of Quantum Theory and Special Relativity in signaling scenarios

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    The coexistence between Quantum Mechanics and Special Relativity is usually formulated in terms of the no-signaling condition. Several authors have even suggested that this condition should be included between the basic postulates of Quantum Theory. However, there are several scenarios where signaling is, in principle, possible: based on previous results and the analysis of the relation between unitarity and signaling we present an example of a two-particle interferometric arrangement for which the dynamics is, in principle, compatible with superluminal transmission of information. This type of non-locality is not in the line of Bell's theorem, but closer in spirit to the one-particle acausality studied by Hegerfeldt and others. We analyze in this paper the meaning of this non-locality and how to preserve the coexistence of the two fundamental theories in this signaling scenario.Comment: See also the comment by G C Hegerfeldt in the online version of the journal, including more reference

    Polarization instabilities in a two-photon laser

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    We describe the operating characteristics of a new type of quantum oscillator that is based on a two-photon stimulated emission process. This two-photon laser consists of spin-polarized and laser-driven 39^{39}K atoms placed in a high-finesse transverse-mode-degenerate optical resonator, and produces a beam with a power of ∼\sim 0.2 μ\mu W at a wavelength of 770 nm. We observe complex dynamical instabilities of the state of polarization of the two-photon laser, which are made possible by the atomic Zeeman degeneracy. We conjecture that the laser could emit polarization-entangled twin beams if this degeneracy is lifted.Comment: Accepted by Physical Review Letters. REVTeX 4 pages, 4 EPS figure

    Interdisciplinary evidence-based recommendations for the follow-up of testicular cancer patients: a joint effort

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    Detailed recommendations for the treatment of testicular cancer exist and due to the stringent application of the standard therapies, most patients can nowadays be cured. Moreover in the treatment of early stage disease, active surveillance is now a cornerstone of treatment. Hence there is a clear need for recommendations regarding the long term follow-up of these young patients. These have to be safe, feasible and the intensity of procedures have to reflect the known risk of recurrence. Different proposals have been published but they differ widely especially in terms of frequency and modality of imaging. In the last few years, new evidence has become available regarding the relapse pattern of different disease stages of testicular cancer, the use of imaging in follow-up and the risks of excessive radiation due to imaging, in particular with CT scans. In this article, an interdisciplinary, multinational working group has reviewed the evidence and based on this has formulated practical recommendations for the follow-up of patients with testicular cancer

    On the Consequences of Retaining the General Validity of Locality in Physical Theory

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    The empirical validity of the locality (LOC) principle of relativity is used to argue in favour of a local hidden variable theory (HVT) for individual quantum processes. It is shown that such a HVT may reproduce the statistical predictions of quantum mechanics (QM), provided the reproducibility of initial hidden variable states is limited. This means that in a HVT limits should be set to the validity of the notion of counterfactual definiteness (CFD). This is supported by the empirical evidence that past, present, and future are basically distinct. Our argumentation is contrasted with a recent one by Stapp resulting in the opposite conclusion, i.e. nonlocality or the existence of faster-than-light influences. We argue that Stapp's argumentation still depends in an implicit, but crucial, way on both the notions of hidden variables and of CFD. In addition, some implications of our results for the debate between Bohr and Einstein, Podolsky and Rosen are discussed.Comment: revtex, 11 page

    Trapped in the prison of the mind: notions of climate-induced (im)mobility decision-making and wellbeing from an urban informal settlement in Bangladesh

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    The concept of Trapped Populations has until date mainly referred to people ‘trapped’ in environmentally high-risk rural areas due to economic constraints. This article attempts to widen our understanding of the concept by investigating climate-induced socio-psychological immobility and its link to Internally Displaced People’s (IDPs) wellbeing in a slum of Dhaka. People migrated here due to environmental changes back on Bhola Island and named the settlement Bhola Slum after their home. In this way, many found themselves ‘immobile’ after having been mobile—unable to move back home, and unable to move to other parts of Dhaka, Bangladesh, or beyond. The analysis incorporates the emotional and psychosocial aspects of the diverse immobility states. Mind and emotion are vital to better understand people’s (im)mobility decision-making and wellbeing status. The study applies an innovative and interdisciplinary methodological approach combining Q-methodology and discourse analysis (DA). This mixed-method illustrates a replicable approach to capture the complex state of climate-induced (im)mobility and its interlinkages to people’s wellbeing. People reported facing non-economic losses due to the move, such as identity, honour, sense of belonging and mental health. These psychosocial processes helped explain why some people ended up ‘trapped’ or immobile. The psychosocial constraints paralysed them mentally, as well as geographically. More empirical evidence on how climate change influences people’s wellbeing and mental health will be important to provide us with insights in how to best support vulnerable people having faced climatic impacts, and build more sustainable climate policy frameworks

    Adult women and ADHD: on the temporal dimensions of ADHD identities

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    This paper uses conceptual resources drawn psychosocial process thinking (Stenner, 2017, Brown and Reavey, 2015, Brown and Stenner, 2009) and from G.H. Mead in particular, to contribute to an emerging body of work on the experiences of adult women with ADHD (Singh, 2002, Waite and Ivey, 2009, Quinn and Madhoo, 2014, Horton-Salway and Davies, 2018). It has a particular focus on how ADHD features in the construction of women’s identities and life-stories and it draws upon findings from a qualitative investigation of adult women diagnosed or self-diagnosed with Attention Deficit Hyperactivity Disorder (ADHD). A theoretically informed ‘thematic decomposition’ of 16 depth interviews reveals how complex processes of identity transformation are mediated by the social category of ADHD. Through this process, pasts are reconstructed from the perspective of an ‘emergent’ identity that offers participants the potential for a more enabling and positive future

    Self-management of chronic low back pain: Four viewpoints from patients and healthcare providers

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    A move towards self-management is central to health strategy around chronic low back pain, but its concept and meaning for those involved are poorly understood. In the reported study, four distinct and shared viewpoints on self-management were identified among people with pain and healthcare providers using Q methodology. Each construes self-management in a distinctive manner and articulates a different vision of change. Identification of similarities and differences among the viewpoints holds potential for enhancing communication between patients and healthcare providers and for better understanding the complexities of self-management in practice

    Affecting qualitative health psychology

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    The ‘affective turn’ is a contemporary movement within the humanities, social science and psychology to investigate affect, emotion and feeling as hybrid phenomena jointly constituted from both biological and social influences. Health and illness are themselves jointly constituted in this way, and many of the topics, concerns and methods of health psychology are strongly permeated by affective phenomena. Qualitative research in health psychology might therefore benefit by engaging with this work. This paper describes some features of the affective turn, and suggests theories, terminology and methods that might be useful
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