6,379 research outputs found

    General formalism of Hamiltonians for realizing a prescribed evolution of a qubit

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    We investigate the inverse problem concerning the evolution of a qubit system, specifically we consider how one can establish the Hamiltonians that account for the evolution of a qubit along a prescribed path in the projected Hilbert space. For a given path, there are infinite Hamiltonians which can realize the same evolution. A general form of the Hamiltonians is constructed in which one may select the desired one for implementing a prescribed evolution. This scheme can be generalized to higher dimensional systems.Comment: 6 page

    History of degenerative spondylolisthesis: From anatomical description to surgical management

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    This review of the historical medical literature aimed at understanding the evolution of surgical management of degenerative spondylolisthesis over time. The Medic@, IndexCat and Gallica historical databases and PubMed and Embase medical databases were used, with several search-terms, exploring the years 1700-2018. Data from anatomical, biomechanical, pathophysiological and surgical studies were compiled. In total, 150 documents were obtained, dating from 1782 to 2018: 139 from PubMed, 1 from Medic@, 7 from IndexCat, and 3 from Gallica. The review thus ranges in time from (1) description of the first clinical cases by several authors in Europe (1782), (2) the identification of a distinct entity by MacNab (1963), and (3) surgical management by the emerging discipline of minimally invasive spine surgery, to its subsequent evolution up to the present day. Spondylolisthesis is a frequent condition potentially responsible for a variety of functional impairments. Understanding and surgical management have progressed since the 20th century. Historically, the first descriptions of treatments concerned only spondylolisthesis associated with spondylolysis, especially in young adults. More recently, there has been progress in the understanding of the disease in elderly people, with the recognition of degenerative spondylolisthesis. New technologies and surgical techniques, aided by advances in supportive care, now provide spine surgeons with powerful treatment tools. Better knowledge of the evolution of surgery throughout history should enable better understanding of current approaches and concepts for treating degenerative spondylolisthesis

    La contratación pública de obras: situación actual y puntos de mejora

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    La construcción pública ha sido, es y será uno de los pilares fundamentales del sector construcción español, si bien la actual situación de crisis económica y la reducción de la inversión pública en nuevas infraestructuras ha generado un descenso de actividad hasta niveles similares a los años noventa. El retorno a índices de actividad más elevados no solo se conseguirá con la recuperación de la economía del país, sino que será necesario realizar ciertas mejoras en los procesos de licitación con objeto de conseguir una mayor funcionalidad y flexibilidad en la contratación pública de obras

    Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement

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    OBJECTIVES There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised. METHODS Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species. RESULTS Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD. DISCUSSION The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine
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