2,136 research outputs found

    Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator

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    We investigate the action of time dependent detunings upon the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator. The method employs the Jaynes-Cummings model with damping, assuming different decay rates of the Cooper pair box and various fixed and t-dependent detunings. It is shown that while the presence of damping plus constant detunings destroy the collapse/revival effects, convenient choices of time dependent detunings allow one to reconstruct such events in a perfect way. It is also shown that the mean excitation of the nanomechanical resonator is more robust against damping of the Cooper pair box for convenient values of t-dependent detunings.Comment: 11 pages, 5 figure

    Sustainable growth in complex networks

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    Based on the empirical analysis of the dependency network in 18 Java projects, we develop a novel model of network growth which considers both: an attachment mechanism and the addition of new nodes with a heterogeneous distribution of their initial degree, k0k_0. Empirically we find that the cumulative degree distributions of initial degrees and of the final network, follow power-law behaviors: P(k0)k01αP(k_{0}) \propto k_{0}^{1-\alpha}, and P(k)k1γP(k)\propto k^{1-\gamma}, respectively. For the total number of links as a function of the network size, we find empirically K(N)NβK(N)\propto N^{\beta}, where β\beta is (at the beginning of the network evolution) between 1.25 and 2, while converging to 1\sim 1 for large NN. This indicates a transition from a growth regime with increasing network density towards a sustainable regime, which revents a collapse because of ever increasing dependencies. Our theoretical framework is able to predict relations between the exponents α\alpha, β\beta, γ\gamma, which also link issues of software engineering and developer activity. These relations are verified by means of computer simulations and empirical investigations. They indicate that the growth of real Open Source Software networks occurs on the edge between two regimes, which are either dominated by the initial degree distribution of added nodes, or by the preferential attachment mechanism. Hence, the heterogeneous degree distribution of newly added nodes, found empirically, is essential to describe the laws of sustainable growth in networks.Comment: 5 pages, 2 figures, 1 tabl

    Application of Adult Learning Theory to Supplemental Instruction in Undergraduate Chemistry Classes

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    The Supplemental Instruction (SI) program relies on the foundations of adult education. In particular it depends heavily on peer support in difficult classes. The andragogical approach highlights the importance of addressing different learning styles and helps students to engage in collaborative learning and problem solving

    Hiperplasia angiolinfoide con eosinofilia: a propósito de una localización atípica en músculo trapecio

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    La hiperplasia angiolinfoide con eosinofilia es una patología poco frecuente de presentación clínica inespecífica que lleva a que rara vez se diagnostique antes del estudio histológico. Habitualmente afecta a piel y tejido celular subcutáneo siendo rara la localización extracutánea. Presentamos un caso clínico de una tumoración en una mujer de 46 años localizada a nivel del músculo trapecio; y revisamos las características histopatológicas y de tratamiento de esta patología.Angiolymphoid hyperplasia with eosinophilia is an uncommon condition with non-specific clinical symptoms that needs a histological study to have the diagnosis. Usually this lesion occurs in the skin and the subcutaneous tissue, with extracutaneous affection being rare. We describe a tumour affecting the trapezius muscle in a 40- year-old woman; and we review the histopathologic findings and the treatment of this pathology

    Osteosarcoma perióstico: caso clínico

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    El osteosarcoma perióstico es un sarcoma raro que asienta en la superficie del hueso. Aunque algunos autores lo incluyen en los osteosarcomas yuxtacorticales sus peculiaridades clínicas, radiológicas y anatomopatológicas entre ellos que llevan a diferencias en el tratamiento y pronóstico le otorgan personalidad propia. Presentamos un caso clínico de osteosarcoma perióstico en un varón de 18 años, a nivel de fémur. Se realiza una revisión de la bibliografía, señalando las principales características de esta entidad.Periosteal osteosarcoma is a rare malignant neoplasm located on bone surface. Although some authors include it among juxtacortical osteosarcoma, its clinical feature, imaging studies findings and histologic patterns which lead to differences in the treatment and prognostic, give to it a peculiar identity. We report a case of an 18 years old man who had this tumour in his femur. We do a review of literature
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