1,089 research outputs found

    Fate of topological states in incommensurate generalized Aubry-Andr\'e models

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    We study one-dimensional optical lattices described by generalized Aubry-Andr\'e models that include both commensurate and incommensurate modulations of the hopping amplitude. This brings together two interesting features of this class of systems: Anderson localization and the existence of topological edge states. We follow changes of the single-particle energy spectrum induced by variations of the system parameters, with focus on the survival of topological states in the localized regime.Comment: 5 pages, 5 figure

    Finite-size effects in Anderson localization of one-dimensional Bose-Einstein condensates

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    We investigate the disorder-induced localization transition in Bose-Einstein condensates for the Anderson and Aubry-Andre models in the non-interacting limit using exact diagonalization. We show that, in addition to the standard superfluid fraction, other tools such as the entanglement and fidelity can provide clear signatures of the transition. Interestingly, the fidelity exhibits good sensitivity even for small lattices. Effects of the system size on these quantities are analyzed in detail, including the determination of a finite-size-scaling law for the critical disorder strength in the case of the Anderson model.Comment: 15 pages, 7 figure

    Upper Cretaceous stratigraphy and rudist-bearing facies of the Simbruini Mts. (Central Apennines, Italy). New field data and a review

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    The rudist-bearing carbonate platform succession of Marsia, in the northern Simbruini Mts. (Central Apennines), is described for the first time through the analysis of two stratigraphic sections, and better characterized by the study of three single significant outcrops located outside the sections. The identification of the rudist assemblages, related facies and micropaleontological analyses of the collected samples allowed to determine the age of this Upper Cretaceous succession, and the definition of a biostratigraphic frame for the of the entire study area. The Marsia composite stratigraphic section encompasses the late Turonian-early/middle Campanian interval, and records the evolution from inner platform-low hydrodynamic setting in the late Turonian, to an open platform setting characterized by high hydrodynamism in the late Santonian-early/middle Campanian. This succession has been compared to the already described Trevi, Santa Maria dei Bisognosi and Subiaco carbonate platform successions, and to regional bioevent schemes, in order to constrain the evolution of these carbonate facies in a wider sedimentological and stratigraphic context. Since the late Turonian, a spreading of rudist facies occurred throughout the central-southern Apennines, representing the first Upper Cretaceous rudist bioevent. In the Simbruini area inner platform environments, characterized by soft fine-grained sediment, are widespread. The successions of Marsia and Trevi, which are marked by upper Turonian inner platform facies with a thriving oligospecific rradiolitid association characterized by semi-infaunal lifestyle, record this bioevent. During the Santonian and the early Campanian a gradual increase in hydrodynamic conditions is recorded by rudist assemblages with hippuritids and robust radiolitids, associated with rare corals and echinoids which mark the second and third Upper Cretaceous rudist bievent, recorded at Marsia, Trevi and Santa Maria dei Bisognosi. The middle Campanian-Maastrichtian bioevents are only represented at Santa Maria dei Bisognosi and Subiaco, where high energy bioclastic facies, dominated by the peculiar radiolitid Sabinia sp., occur

    O PROCESSO DE ENSINAR E APRENDER ENFERMAGEM.

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    El artículo presenta un estudio de caso que tiene como objetivo conocer de forma profunda una práctica educativa desde su concepción hasta su evaluación, apuntando algunos puntos frágiles en la forma de desarrollo de la enseñanza así como estrategias que permitan su superación. Para atender al objetivo propuesto, se siguió el desarrollo de una disciplina práctica de un curso de graduación en enfermería durante un semestre lectivo. Los resultados encontrados indican que la forma de comunicación establecida entre los diversos sujetos, alumnas, profesores, pacientes, ejerce un papel fundamental en el desarrollo de todo proceso.O artigo apresenta um estudo de caso que teve como objetivo conhecer de forma profunda uma prática educativa desde sua concepção até sua avaliação, apontando alguns pontos frágeis na forma de desenvolvimento do ensino assim como estratégias que podem permitir sua superação. Para atingir o objetivo proposto, foi acompanhado o desenvolvimento de uma disciplina prática de um curso de graduação em enfermagem durante um semestre letivo. Os resultados encontrados indicam que a forma de comunicação estabelecida entre os diversos sujeitos, alunas, professoras, pacientes, exerce papel fundamental no desenvolvimento de todo o processo

    Decreased Vision and Junctional Scotoma from Pituicytoma

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    Pituicytomas are rare neoplasms of the sellar region. We report a case of vision loss and a junctional scotoma in a 43-year-old woman caused by compression of the optic chiasm by a pituitary tumor. The morphological and immunohistochemical characteristics of the tumor were consistent with the diagnosis of pituicytoma. The tumor was debulked surgically, and the patient's vision improved

    Critical exponents of the disorder-driven superfluid-insulator transition in one-dimensional Bose-Einstein condensates

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    We investigate the nature of the superfluid-insulator quantum phase transition driven by disorder for non-interacting ultracold atoms on one-dimensional lattices. We consider two different cases: Anderson-type disorder, with local energies randomly distributed, and pseudo-disorder due to a potential incommensurate with the lattice, which is usually called the Aubry-Andr\'e model. A scaling analysis of numerical data for the superfluid fraction for different lattice sizes allows us to determine quantum critical exponents characterizing the disorder-driven superfluid-insulator transition. We also briefly discuss the effect of interactions close to the non-interacting quantum critical point of the Aubry-Andr\'e model.Comment: 5 pages, 4 figure

    investigation of particle dynamics and classification mechanism in a spiral jet mill through computational fluid dynamics and discrete element methods

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    Abstract Predicting the outcome of jet-milling based on the knowledge of process parameters and starting material properties is a task still far from being accomplished. Given the technical difficulties in measuring thermodynamics, flow properties and particle statistics directly in the mills, modelling and simulations constitute alternative tools to gain insight in the process physics and many papers have been recently published on the subject. An ideal predictive simulation tool should combine the correct description of non-isothermal, compressible, high Mach number fluid flow, the correct particle-fluid and particle-particle interactions and the correct fracture mechanics of particle upon collisions but it is not currently available. In this paper we present our coupled CFD-DEM simulation results; while comparing them with the recent modelling and experimental works we will review the current understating of the jet-mill physics and particle classification. Subsequently we analyze the missing elements and the bottlenecks currently limiting the simulation technique as well as the possible ways to circumvent them towards a quantitative, predictive simulation of jet-milling

    Phenotypic impacts of CSF1R deficiencies in humans and model organisms

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    Mϕ proliferation, differentiation, and survival are controlled by signals from the Mϕ CSF receptor (CSF1R). Mono‐allelic gain‐of‐function mutations in CSF1R in humans are associated with an autosomal‐dominant leukodystrophy and bi‐allelic loss‐of‐function mutations with recessive skeletal dysplasia, brain disorders, and developmental anomalies. Most of the phenotypes observed in these human disease states are also observed in mice and rats with loss‐of‐function mutations in Csf1r or in Csf1 encoding one of its two ligands. Studies in rodent models also highlight the importance of genetic background and likely epistatic interactions between Csf1r and other loci. The impacts of Csf1r mutations on the brain are usually attributed solely to direct impacts on microglial number and function. However, analysis of hypomorphic Csf1r mutants in mice and several other lines of evidence suggest that primary hydrocephalus and loss of the physiological functions of Mϕs in the periphery contribute to the development of brain pathology. In this review, we outline the evidence that CSF1R is expressed exclusively in mononuclear phagocytes and explore the mechanisms linking CSF1R mutations to pleiotropic impacts on postnatal growth and development

    Analysis of the impact of Colony Stimulating Factor (CSF)-1 administration in adult rats using a novel Csf1r-mApple reporter gene

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    Macrophages are present in large numbers in every tissue in the body where they play critical roles in development and homeostasis. They exhibit remarkable phenotypic and functional diversity, underpinning their adaptation to specialized roles in each tissue niche. CSF1, signaling through the CSF1 receptor, which is restricted to monocyte-macrophage lineage cells in adults, is a critical growth factor controlling macrophage proliferation, differentiation, and many aspects of mature macrophage function. We have generated a macrophage reporter rat, utilizing a construct containing elements of the mouse Csf1r promoter and the highly conserved Fms intronic regulatory element to drive mApple fluorescent protein expression. Csf1r-mApple was robustly expressed in monocyte-macrophage lineage cells in rat bone marrow (BM), peripheral blood, and tissues, with detectable expression in granulocytes and B cells and no evidence of expression in hematopoietic precursors or non-hematopoietic cells. Here, we use the Csf1r-mApple transgene to highlight and dissect the abundance and heterogeneity of rat tissue macrophage populations, and to demonstrate parallel increases in blood monocytes and multiple tissue macrophage populations, including BM, liver, spleen, and lung, in response to CSF1 treatment in vivo. The Csf1r-mApple rat is a novel tool enabling analysis of rat macrophages in situ by direct imaging and providing an additional phenotypic marker to facilitate exploration of rat tissue macrophage phenotypic and functional heterogeneity
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