3,747 research outputs found

    Finite-size scaling considerations on the ground state microcanonical temperature in entropic sampling simulations

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    In this work we discuss the behavior of the microcanonical temperature S(E)E\frac{\partial S(E)}{\partial E} obtained by means of numerical entropic sampling studies. It is observed that in almost all cases the slope of the logarithm of the density of states S(E)S(E) is not infinite in the ground state, since as expected it should be directly related to the inverse temperature 1T\frac{1}{T}. Here we show that these finite slopes are in fact due to finite-size effects and we propose an analytic expression aln(bL)a\ln(bL) for the behavior of ΔSΔE\frac{\varDelta S}{\varDelta E} when LL\rightarrow\infty. To test this idea we use three distinct two-dimensional square lattice models presenting second-order phase transitions. We calculated by exact means the parameters aa and bb for the two-states Ising model and for the q=3q=3 and 44 states Potts model and compared with the results obtained by entropic sampling simulations. We found an excellent agreement between exact and numerical values. We argue that this new set of parameters aa and bb represents an interesting novel issue of investigation in entropic sampling studies for different models

    Harmonic analysis on the Möbius gyrogroup

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    In this paper we propose to develop harmonic analysis on the Poincaré ball BtnB_t^n, a model of the n-dimensional real hyperbolic space. The Poincaré ball BtnB_t^n is the open ball of the Euclidean n-space RnR^n with radius t>0t>0, centered at the origin of RnR^n and equipped with Möbius addition, thus forming a Möbius gyrogroup where Möbius addition in the ball plays the role of vector addition in Rn\mathbb{R}^n. For any t>0t>0 and an arbitrary parameter σR\sigma \in R we study the (σ,t)(\sigma,t)-translation, the (σ,t)( \sigma,t)-convolution, the eigenfunctions of the (σ,t)(\sigma,t)-Laplace-Beltrami operator, the (σ,t)(\sigma,t)-Helgason Fourier transform, its inverse transform and the associated Plancherel's Theorem, which represent counterparts of standard tools, thus, enabling an effective theory of hyperbolic harmonic analysis. Moreover, when t+t \rightarrow +\infty the resulting hyperbolic harmonic analysis on BtnB_t^n tends to the standard Euclidean harmonic analysis on RnR^n, thus unifying hyperbolic and Euclidean harmonic analysis. As an application we construct diffusive wavelets on BtnB_t^n

    Building the Brazilian Academic Genealogy Tree

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    Along the history, many researchers provided remarkable contributions to science, not only advancing knowledge but also in terms of mentoring new scientists. Currently, identifying and studying the formation of researchers over the years is a challenging task as current repositories of theses and dissertations are cataloged in a decentralized way through many local digital libraries. Following our previous work in which we created and analyzed a large collection of genealogy trees extracted from NDLTD, in this paper we focus our attention on building such trees for the Brazilian research community. For this, we use data from the Lattes Platform, an internationally renowned initiative from CNPq, the Brazilian National Council for Scientific and Technological Development, for managing information about individual researchers and research groups in Brazil

    Differential Internalization of Amphotericin B - Conjugated Nanoparticles in Human Cells and the Expression of Heat Shock Protein 70

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    Although a variety of nanoparticles (NPs) functionalized with amphotericin B, an antifungal agent widely used in the clinic, have been studied in the last years their cytotoxicity profile remains elusive. Here we show that human endothelial cells take up high amounts of silica nanoparticles (SNPs) conjugated with amphotericin B (AmB) (SNP-AmB) (65.4 12.4 pg of Si per cell) through macropinocytosis while human fibroblasts internalize relatively low amounts (2.3 0.4 pg of Si per cell) because of their low capacity for macropinocytosis. We further show that concentrations of SNP-AmB and SNP up to 400 mg/mL do not substantially affect fibroblasts. In contrast, endothelial cells are sensitive to low concentrations of NPs (above 10 mg/mL), in particular to SNP-AmB. This is because of their capacity to internalize high concentration of NPs and high sensitivity of their membrane to the effects of AmB. Low-moderate concentrations of SNP-AmB (up to 100 mg/mL) induce the production of reactive oxygen species (ROS), LDH release, high expression of pro-inflammatory cytokines and chemokines (IL-8, IL-6, G-CSF, CCL4, IL-1b and CSF2) and high expression of heat shock proteins (HSPs) at gene and protein levels. High concentrations of SNP-AmB (above 100 ug/mL) disturb membrane integrity and kill rapidly human cells(60% after 5 h). This effect is higher in SNP-AmB than in SNP

    Patient-doctor continuity and diagnosis of cancer: electronic medical records study in general practice

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    This is the final version of the article. Available from Royal College of General Practitioners via the DOI in this record.BACKGROUND: Continuity of care may affect the diagnostic process in cancer but there is little research. AIM: To estimate associations between patient-doctor continuity and time to diagnosis and referral of three common cancers. DESIGN AND SETTING: Retrospective cohort study in general practices in England. METHOD: This study used data from the General Practice Research Database for patients aged ≥40 years with a diagnosis of breast, colorectal, or lung cancer. Relevant cancer symptoms or signs were identified up to 12 months before diagnosis. Patient-doctor continuity (fraction-of-care index adjusted for number of consultations) was calculated up to 24 months before diagnosis. Time ratios (TRs) were estimated using accelerated failure time regression models. RESULTS: Patient-doctor continuity in the 24 months before diagnosis was associated with a slightly later diagnosis of colorectal (time ratio [TR] 1.01, 95% confidence interval [CI] =1.01 to 1.02) but not breast (TR = 1.00, 0.99 to 1.01) or lung cancer (TR = 1.00, 0.99 to 1.00). Secondary analyses suggested that for colorectal and lung cancer, continuity of doctor before the index consultation was associated with a later diagnosis but continuity after the index consultation was associated with an earlier diagnosis, with no such effects for breast cancer. For all three cancers, most of the delay to diagnosis occurred after referral. CONCLUSION: Any effect for patient-doctor continuity appears to be small. Future studies should compare investigations, referrals, and diagnoses in patients with and without cancer who present with possible cancer symptoms or signs; and focus on 'difficult to diagnose' types of cancer.This work was funded by Cancer Research UK (C41384/A13266)

    Field theory of scaling lattice models. The Potts antiferromagnet

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    In contrast to what happens for ferromagnets, the lattice structure participates in a crucial way to determine existence and type of critical behaviour in antiferromagnetic systems. It is an interesting question to investigate how the memory of the lattice survives in the field theory describing a scaling antiferromagnet. We discuss this issue for the square lattice three-state Potts model, whose scaling limit as T->0 is argued to be described exactly by the sine-Gordon field theory at a specific value of the coupling. The solution of the scaling ferromagnetic case is recalled for comparison. The field theory describing the crossover from antiferromagnetic to ferromagnetic behaviour is also introduced.Comment: 11 pages, to appear in the proceedings of the NATO Advanced Research Workshop on Statistical Field Theories, Como 18-23 June 200

    Universality in Systems with Power-Law Memory and Fractional Dynamics

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    There are a few different ways to extend regular nonlinear dynamical systems by introducing power-law memory or considering fractional differential/difference equations instead of integer ones. This extension allows the introduction of families of nonlinear dynamical systems converging to regular systems in the case of an integer power-law memory or an integer order of derivatives/differences. The examples considered in this review include the logistic family of maps (converging in the case of the first order difference to the regular logistic map), the universal family of maps, and the standard family of maps (the latter two converging, in the case of the second difference, to the regular universal and standard maps). Correspondingly, the phenomenon of transition to chaos through a period doubling cascade of bifurcations in regular nonlinear systems, known as "universality", can be extended to fractional maps, which are maps with power-/asymptotically power-law memory. The new features of universality, including cascades of bifurcations on single trajectories, which appear in fractional (with memory) nonlinear dynamical systems are the main subject of this review.Comment: 23 pages 7 Figures, to appear Oct 28 201

    R&D DYNAMICS

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    We study a Cournot duopoly model using Ferreira-Oliveira-Pinto's R&D investment function. We find the multiple perfect Nash equilibria and we analyse the economical relevant quantities like output levels, prices, consumer surplus, profits and welfare
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