1,761 research outputs found

    Construction of a non-standard quantum field theory through a generalized Heisenberg algebra

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    We construct a Heisenberg-like algebra for the one dimensional quantum free Klein-Gordon equation defined on the interval of the real line of length LL. Using the realization of the ladder operators of this type Heisenberg algebra in terms of physical operators we build a 3+1 dimensional free quantum field theory based on this algebra. We introduce fields written in terms of the ladder operators of this type Heisenberg algebra and a free quantum Hamiltonian in terms of these fields. The mass spectrum of the physical excitations of this quantum field theory are given by n2π2/L2+mq2\sqrt{n^2 \pi^2/L^2+m_q^2}, where n=1,2,...n= 1,2,... denotes the level of the particle with mass mqm_q in an infinite square-well potential of width LL.Comment: Latex, 16 page

    Generalized quantum field theory: perturbative computation and perspectives

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    We analyze some consequences of two possible interpretations of the action of the ladder operators emerging from generalized Heisenberg algebras in the framework of the second quantized formalism. Within the first interpretation we construct a quantum field theory that creates at any space-time point particles described by a q-deformed Heisenberg algebra and we compute the propagator and a specific first order scattering process. Concerning the second one, we draw attention to the possibility of constructing this theory where each state of a generalized Heisenberg algebra is interpreted as a particle with different mass.Comment: 19 page

    An institutional palimpsest? The case of Cambodia’s political order, 1970 and beyond

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    How do continuity and change coexist and coevolve? How does continuity enable change and change reinforce continuity? These are central questions in organizational and political research, as organizational and institutional systems benefit from the presence of both reproduction and transformation. However, the relation between the processes of change and continuity still raises significant questions. To contribute to this discussion, we analyse the coexistence of deep institutional continuity and radical political change in the second half of twentieth-century Cambodia. Over a two-decade period, Cambodia was ruled by radically different political systems of organization: a traditional monarchy with feudal characteristics, a failing republic, a totalitarian communist regime, and a Vietnamese protectorate, before being governed by the UN and finally becoming a constitutional monarchy. We use an historical approach to study how a succession of radical changes may in reality signal deep lines of continuity.info:eu-repo/semantics/acceptedVersio

    Construction of coherent states for physical algebraic systems

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    We construct a general state which is an eigenvector of the annihilation operator of the Generalized Heisenberg Algebra. We show for several systems, which are characterized by different energy spectra, that this general state satisfies the minimal set of conditions required to obtain Klauder's minimal coherent states.Comment: 15 pages, 3 figure

    Long-Term Survival (>25 Years) of Deceased Donor Kidney Transplant Recipients: a Single-Center Experience

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    INTRODUCTION: The aim of this preliminary work is to analyze the clinical features of 52 patients with a functional transplanted kidney for >25 years (all first transplant and all deceased donor recipients) and to compare with a similar though more complete study from Hôpital Necker-Paris 2012. METHODS: The mean graft survival at 25 years is 12.7% and at 30 years is 10%. The actual mean serum creatinine concentration is 1.3 mg/L. We analyzed recipient age (mean, 35.9 years) and gender (29 men and 23 women). Donor age was 26.7 ± 10.3 years. Seven patients (13.4%) were transplanted with 1 HLA mismatch, 42.3% with 2 mismatches, and 44.2% with 3 mismatches. Mean cold ischemia time was 15.45 ± 7.7 hours. Of the recipients, 76% had immediate graft function; 38% experienced 1 acute rejection episode and 4 patients had 2 rejection crises. The initial immunosuppressive regimen was azathioprine (AZA) + prednisolone (Pred) in 14 patients, cyclosporin (CSA) + Pred in 13 patients, and CSA + AZA + Pred in 25 patients. Of these patients, 19% maintained their initial regimen, and 54% (28 patients) were very stable on a mixed CSA regimen for >25 years. RESULTS: We present the major complications (diabetes, neoplasia, and hepatitis C virus positivity). CONCLUSION: Our results in deceased donor kidney recipients for >25 years are similar to the mixed population (deceased donors and living donors) presented by the Necker group, although 54% of our patients remain on CSA immunosuppression, contradicting the idea that its use is not compatible with good long-term kidney function in transplant recipients
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