1,103 research outputs found

    Anthropic versus cosmological solutions to the coincidence problem

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    In this paper we investigate possible solutions to the coincidence problem in flat phantom dark energy models with a constant dark energy equation of state and quintessence models with a linear scalar field potential. These models are representative of a broader class of cosmological scenarios in which the universe has a finite lifetime. We show that, in the absence of anthropic constraints, including a prior probability for the models inversely proportional to the total lifetime of the universe excludes models very close to the ΛCDM\Lambda {\rm CDM} model. This relates a cosmological solution to the coincidence problem with a dynamical dark energy component having an equation of state parameter not too close to -1 at the present time. We further show, that anthropic constraints, if they are sufficiently stringent, may solve the coincidence problem without the need for dynamical dark energy.Comment: 7 pages, 7 figure

    Recurrence spectrum in smooth dynamical systems

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    We prove that for conformal expanding maps the return time does have constant multifractal spectrum. This is the counterpart of the result by Feng and Wu in the symbolic setting

    Generalized nonuniform dichotomies and local stable manifolds

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    We establish the existence of local stable manifolds for semiflows generated by nonlinear perturbations of nonautonomous ordinary linear differential equations in Banach spaces, assuming the existence of a general type of nonuniform dichotomy for the evolution operator that contains the nonuniform exponential and polynomial dichotomies as a very particular case. The family of dichotomies considered allow situations for which the classical Lyapunov exponents are zero. Additionally, we give new examples of application of our stable manifold theorem and study the behavior of the dynamics under perturbations.Comment: 18 pages. New version with minor corrections and an additional theorem and an additional exampl

    Exhibiting cross-diffusion-induced patterns for reaction-diffusion systems on evolving domains and surfaces

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    The aim of this manuscript is to present for the first time the application of the finite element method for solving reaction-diffusion systems with cross-diffusion on continuously evolving domains and surfaces. Furthermore we present pattern formation generated by the reaction-diffusion systemwith cross-diffusion on evolving domains and surfaces. A two-component reaction-diffusion system with linear cross-diffusion in both u and v is presented. The finite element method is based on the approximation of the domain or surface by a triangulated domain or surface consisting of a union of triangles. For surfaces, the vertices of the triangulation lie on the continuous surface. A finite element space of functions is then defined by taking the continuous functions which are linear affine on each simplex of the triangulated domain or surface. To demonstrate the role of cross-diffusion to the theory of pattern formation, we compute patterns with model kinetic parameter values that belong only to the cross-diffusion parameter space; these do not belong to the standard parameter space for classical reaction-diffusion systems. Numerical results exhibited show the robustness, flexibility, versatility, and generality of our methodology; the methodology can deal with complicated evolution laws of the domain and surface, and these include uniform isotropic and anisotropic growth profiles as well as those profiles driven by chemical concentrations residing in the domain or on the surface

    Bladder Cancer New Biomarkers in Liquid Biopsies

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    Bladder cancer is one of the most common neoplasia in men in the developed countries. Diagnosis and surveillance are made by bladder examination through cystoscopy making this one of the most expensive on cost/patient. After tumor removal, clinical staging is important for prognosis and treatment decision as non-muscle invasive (Ta and T1) and invasive (T2+) are treated in a completely different way. Today no noninvasive method has enough sensitivity to substitute cystoscopy or histological examination for tumor clinical staging. Our aim is to identify and quantify in urine, proteins that can detect and classify bladder tumors. A biomarker study was conducted using urine samples from: individuals with bladder cancer; individuals with other genitourinary disorders and individuals without urological diseases. Several proteins were found to successfully help in the discrimination of the bladder cancer stages Ta, T1 and T2+. Two biomarkerpanels were developed, one capable of detecting bladder cancer presence and other able to distinguish Ta, T1 and T2+. Our results show a significant difference between urinary proteome in patients with different bladder cancer stages. This may allow through liquid biopsies predict patient’s cancer stage. A validation study is on progress to attest this biomarker panel’s accuracy.info:eu-repo/semantics/publishedVersio

    Physics with nonperturbative quantum gravity: radiation from a quantum black hole

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    We study quantum gravitational effects on black hole radiation, using loop quantum gravity. Bekenstein and Mukhanov have recently considered the modifications caused by quantum gravity on Hawking's thermal black-hole radiation. Using a simple ansatz for the eigenstates the area, they have obtained the intriguing result that the quantum properties of geometry affect the radiation considerably, yielding a definitely non-thermal spectrum. Here, we replace the simple ansatz employed by Bekenstein and Mukhanov with the actual eigenstates of the area, computed using the loop representation of quantum gravity. We derive the emission spectra, using a classic result in number theory by Hardy and Ramanujan. Disappointingly, we do not recover the Bekenstein-Mukhanov spectrum, but --effectively-- a Hawking's thermal spectrum. The Bekenstein-Mukhanov result is therefore likely to be an artefact of the naive ansatz, rather than a robust result. The result is an example of concrete (although somewhat disappointing) application of nonperturbative quantum gravity.Comment: 4 pages, latex-revtex, no figure

    OS Planos Municipais de Educaçao no Tocantins : Arqueologia dos processos de construçao e perspectivas de regime de colaboraçao e da gestao democrática

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    O trabalho apresenta resultados de pesquisa acerca das políticas de educaçao no Brasil, do princípio regime de colaboraçao e da gestao da educaçao, apresentando, neste momento, aspectos da trajetória sociopolítica da elaboraçao ou adequaçao dos Planos Municipais de Educaçao (PMEs), deflagrada em 2013 pelo MEC/SASE, com as possibilidades de efetivaçao do regime de colaboraçao e da gestao democrática. Sua abordagem é qualitativa, de caráter teórico-empírico e exploratório, abarcando a documentaçao relativa aos PMEs dos Municípios. No Tocantins, até o início do ano de 2014, um georreferenciamento demonstra que dos 139 Municípios, apenas seis elaboraram seus PMEs. Neste contexto, predomina a visao de administraçao municipal restrita às suas instituiçoes escolares e ao tempo de sua gestao, sem relaçao ou articulaçao com metas nacionais comuns com vistas à materializaçao do Sistema Nacional de Educaçao. Deste processo, destaca-se o significativo movimento sociopolítico em torno do planejamento da educaçao no século XXI, enfrentado o desafio de definir o objetivo comum da educaçao brasileira. Entretanto, há ideias que merecem ser investigadas, como a sua concepçao de gestao e planejamento e as formas de colaboraçao estabelecida

    A Giant Hand Lipoma As a Rare Cause of Secondary Carpal Tunnel Syndrome - a Case Report

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    Introduction: Lipomas are a rare cause of compressive neuropathy and they lead to atypical clinical presentation that can mimic carpal tunnel syndrome. Case presentation: The authors describe a rare presentation of a carpal tunnel syndrome recurrence after a hand giant lipoma, presenting with rapidly compression neuropathy of the median nerve, 6 months after de primary surgery. Discussion: Lipomas are common benign soft tumours. Their occurrence in the hand remains rare and they rarely cause secondary entrapment neuropathies. Carpal tunnel syndrome is mostly idiopathic and bilateral. Local factors should be suspected when these neuropathies present with atypical symptomatology or even when they recur after primary conventional surgical release. Investigation should consider images studies as this correct preoperative assessment leads to successful diagnosis and treatment.info:eu-repo/semantics/publishedVersio

    Thermodynamic formalism for contracting Lorenz flows

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    We study the expansion properties of the contracting Lorenz flow introduced by Rovella via thermodynamic formalism. Specifically, we prove the existence of an equilibrium state for the natural potential ϕ^t(x,y,z):=tlogJ(x,y,z)cu\hat\phi_t(x,y, z):=-t\log J_{(x, y, z)}^{cu} for the contracting Lorenz flow and for tt in an interval containing [0,1][0,1]. We also analyse the Lyapunov spectrum of the flow in terms of the pressure

    Double scattering of light from biophotonic nanostructures with short-range order

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    We investigate the physical mechanism for color production by isotropic nanostructures with short-range order in bird feather barbs. While the primary peak in optical scattering spectra results from constructive interference of singly-scattered light, many species exhibit secondary peaks with distinct characteristic. Our experimental and numerical studies show that these secondary peaks result from double scattering of light by the correlated structures. Without an analog in periodic or random structures, such a phenomenon is unique for short-range ordered structures, and has been widely used by nature for non-iridescent structural coloration.Comment: 10 pages, 4 figure
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