3,771 research outputs found

    Detection of Multiparticle Entanglement: Quantifying the Search for Symmetric Extensions

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    We provide quantitative bounds on the characterisation of multiparticle separable states by states that have locally symmetric extensions. The bounds are derived from two-particle bounds and relate to recent studies on quantum versions of de Finetti's theorem. We discuss algorithmic applications of our results, in particular a quasipolynomial-time algorithm to decide whether a multiparticle quantum state is separable or entangled (for constant number of particles and constant error in the LOCC or Frobenius norm). Our results provide a theoretical justification for the use of the Search for Symmetric Extensions as a practical test for multiparticle entanglement.Comment: 5 pages, 1 figur

    Inertial-Hall effect: the influence of rotation on the Hall conductivity

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    Inertial effects play an important role in classical mechanics but have been largely overlooked in quantum mechanics. Nevertheless, the analogy between inertial forces on mass particles and electromagnetic forces on charged particles is not new. In this paper, we consider a rotating non-interacting planar two-dimensional electron gas with a perpendicular uniform magnetic field and investigate the effects of the rotation in the Hall conductiv

    Entangled inputs cannot make imperfect quantum channels perfect

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    Entangled inputs can enhance the capacity of quantum channels, this being one of the consequences of the celebrated result showing the non-additivity of several quantities relevant for quantum information science. In this work, we answer the converse question (whether entangled inputs can ever render noisy quantum channels have maximum capacity) to the negative: No sophisticated entangled input of any quantum channel can ever enhance the capacity to the maximum possible value; a result that holds true for all channels both for the classical as well as the quantum capacity. This result can hence be seen as a bound as to how "non-additive quantum information can be". As a main result, we find first practical and remarkably simple computable single-shot bounds to capacities, related to entanglement measures. As examples, we discuss the qubit amplitude damping and identify the first meaningful bound for its classical capacity.Comment: 5 pages, 2 figures, an error in the argument on the quantum capacity corrected, version to be published in the Physical Review Letter

    Tourism innovation networks: A regional approach

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    In the last decades, the innovation process experienced a significant evolution. From the early atomist models, the economy is moving towards systemic approaches based on interactive processes, strongly attached to the territories. Innovation networks are proliferating as the most suited framework for destinations to achieve a high innovation performance. However, there has been little research on the structure and dynamics of tourism innovation networks and how they can foster regional innovation. This paper applies Social Network Analysis to measure and identify the dynamics of cooperation within institutional tourism innovation networks and the role they play on tourism innovation. The study was applied to two Portuguese regions, Douro and Aveiro, where the top managers of institutions responsible for developing or supporting tourism innovation were surveyed. Results demonstrate that different social structures and patterns of cooperation create distinct impacts on regional innovation. It is concluded that tourism destinations characterised by diversified networks, i.e. networks comprising actors from different geographical locations and with distinct typologies, are in a better position to achieve a higher innovation performance. The paper advances strategic recommendations for tourism organisations to increase destinations’ competitiveness, by further developing the necessary conditions for innovation to occur

    Mapping mass customization

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    Mass customization (MC) and personal fabrication (PF) are current relevant topics in architecture offices practice and schools design research. Architects are adopting information based design and production techniques as a response to architectural century challenges. However, is not clear how various authors used and transformed the concept in practice, research and industry after three decades since the MC term was introduced by Davis (1987). Therefore, is essential to map the most relevant works in the field in relation to production and design control. The paper presents some of the results of the ongoing study through an evolving map that aims to visualize relationships, layering complexity and revealing difference.info:eu-repo/semantics/publishedVersio

    Baixa massa óssea em crianças e adolescentes

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    Osteoporosis is a disease characterized by low bone mass and micro architectural alterations of bone tissue leading to enhanced bone fragility and increased fracture risk. Although research in osteoporosis has focused mainly on the role of bone loss in the elderly population, it is becoming increasingly clear that the amount of bone that is gained during growth is also an important determinant of future resistance to fractures. Thus, considerable interest is being placed on defining preventive strategies that optimize the gain of bone mass during childhood and adolescence. Knowledge of the determinants accounting for the physiologic and genetic variations in bone accumulation in children will provide the best means toward the early diagnosis and treatment of osteoporosis. This article reviews the techniques available for bone mass measurements in children and the major determinants and diseases influencing bone accretion during childhood and adolescence.Osteoporose é uma doença caracterizada pela baixa massa óssea e alterações de micro arquitetura do tecido ósseo, levando ao aumento da fragilidade óssea e aumento do risco de fratura. Apesar da pesquisa em osteoporose ter focalizado principalmente no papel da perda óssea na população idosa, está começando a ficar claro que a quantidade de osso que é ganho durante o crescimento é também um determinante importante de resistência futura para fraturas. Portanto, interesse considerável está sendo colocado na definição de estratégias preventivas que otimizam o ganho de massa óssea durante a infância e adolescência. O conhecimento dos determinantes responsáveis pelas variações fisiológicas e genéticas, na acumulação óssea nas crianças, irá levar aos melhores meios para o diagnóstico precoce e tratamento da osteoporose. Este artigo revê as técnicas disponíveis para a medida da massa óssea em crianças e os maiores determinantes e doenças que influenciam a aquisição óssea durante a infância e adolescência.Universidade Catolica de BrasiliaFederal University of São Paulo EPM Division of EndocrinologyFleury - Diagnostic MedicineUNIFESP, EPM, Division of EndocrinologySciEL
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