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Search Results: 1 - 10 of 18525 matches for " U. Simeoni "
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Developmental Origins of Chronic Renal Disease: An Integrative Hypothesis
F. Boubred,M. Saint-Faust,C. Buffat,I. Ligi,I. Grandvuillemin,U. Simeoni
International Journal of Nephrology , 2013, DOI: 10.1155/2013/346067
Abstract: Cardiovascular diseases are one of the leading causes of mortality. Hypertension (HT) is one of the principal risk factors associated with death. Chronic kidney disease (CKD), which is probably underestimated, increases the risk and the severity of adverse cardiovascular events. It is now recognized that low birth weight is a risk factor for these diseases, and this relationship is amplified by a rapid catch-up growth or overfeeding during infancy or childhood. The pathophysiological and molecular mechanisms involved in the “early programming” of CKD are multiple and partially understood. It has been proposed that the developmental programming of arterial hypertension and chronic kidney disease is related to a reduced nephron endowment. However, this mechanism is still discussed. This review discusses the complex relationship between birth weight and nephron endowment and how early growth and nutrition influence long term HT and CKD. We hypothesize that fetal environment reduces moderately the nephron number which appears insufficient by itself to induce long term diseases. Reduced nephron number constitutes a “factor of vulnerability” when additional factors, in particular a rapid postnatal growth or overfeeding, promote the early onset of diseases through a complex combination of various pathophysiological pathways. 1. Introduction Cardiovascular diseases ((CVD) hypertension, coronary disease and stroke, and heart failure) are one of the leading causes of mortality in industrialized countries, and the prevalence is increasing in emerging societies. All cardiovascular diseases account for 4.3 million deaths per year in the European Union, and the prevalence of chronic heart failure in the United States of America is approximately 6 million [1, 2]. In industrialized countries, hypertension (HT) affects 25% to 35% of the global population and reaches 60% to 70% of the population aged 60 or more. Hypertension is the principal risk factor of death worldwide [3]. It increases the severity of ischemic vascular diseases and, with obesity and type 2 diabetes, is one of the important risk factors for chronic kidney disease (CKD). Chronic kidney disease is defined as reduced glomerular filtration rate (GFR) up to end-stage renal disease (ESRD), proteinuria, or both. Prevalence of ESRD, estimated to be 0.5–2.5‰ worldwide, is increasing in several countries [4]. In turn, impaired renal factor favors the development of and amplifies the severity of CVD [5–7]. During the last two decades, it has been raised the concept of developmental programming of adult chronic
Serravallian (Miocene) nannofossils in Patagonia, Argentina [Nannofósiles del Serravalliano (Mioceno) en Patagonia, Argentina]
Simeoni Margarita
Carnets de Géologie , 2009,
Abstract: For the first time, nannofossils found in the marine stratigraphic unit named "Patagoniano" which crops out at Cerro Chenque and Cerro Hermitte in southeastern Chubut, Argentina, are documented. They were recovered from pelitic levels in the lower part of coarsening-upward siliciclastic sedimentary sequences. The nannofossils are assigned in part to the Discoaster kugleri Zone NN7 (Martini, 1971) and CN5b (Bukry, 1971, 1973) thus allowing correlation of the productive levels with the Serravallian Stage (upper Middle Miocene).
Holocene cuspate forelands in the Strait of Magellan, southern Chile
Giorgio Fontolan,Umberto Simeoni
Revista geológica de Chile , 1999,
Transition from isotropic to anisotropic beam profiles in a linear focusing channel
Wilson Simeoni Jr
Physics , 2009,
Abstract: This paper examines the transition from isotropic to anisotropic beam profiles in a linear focusing channel. Considering a high-intensity ion beam in space-charge dominated regime and large mismatched {\it RMS} beam size initially, observe a fast anisotropy situation of the beam, characterized for a transition of the transversal section round to elliptical with a coupling of transversal emittance driven for instabilities of nonlinear space-charge forces. Space-charge interactions in high-intensity linear accelerator can lead to equipartitioning of energy between the degrees of freedom. The anisotropization phenomena suggest a kind of route to equipartition. In order to understand the initial dynamical behavior of an anisotropic beam, in particular, to study possible mechanisms of equipartition connected with phase space we have to know how we can compute the variables (volume, area of surface, and area projected) that characterize the anisotropic beam in phase space. The purpose of this paper is to propose one definiton of the anisotropic equipartition \cite{Yankov1}. Anisotropic equipartition corresponds to a phase space density uniform on the surface invariant of the $\xi$, a version of the ergodic hypothesis where the $\xi$ invariant play the role of the conserved energy \cite{Kandrup3}. In the state of anisotropic equipartition, the beam temperature is stationary, the entropy grows in the cascade form, there is a coupling of transversal emittance, the beam develops an elliptical shape with a increase in its size along one direction and there is halo formation along one direction preferential.
Vector Meson Exchanges and CP Asymmetry in $K^{\pm}\rightarrowπ^{\pm}π^0$
Riazuddin,N. Paver,F. Simeoni
Physics , 1993, DOI: 10.1016/0370-2693(93)90344-H
Abstract: Using a current algebra framework, we discuss the contribution of vector meson exchanges to the CP violating asymmetry in the decay $K^{\pm}\rightarrow\pi^{\pm}\pi^0$, resulting from the interference of the $K\rightarrow\pi\pi$ amplitude with the radiative correction $K\rightarrow\pi\pi\gamma$.
Indirect Optimization of Satellite Deployment into a Highly Elliptic Orbit
Francesco Simeoni,Lorenzo Casalino,Alessandro Zavoli,Guido Colasurdo
International Journal of Aerospace Engineering , 2012, DOI: 10.1155/2012/152683
Abstract: The analysis of the optimal strategies for the deployment of a spacecraft into a highly elliptic orbit is carried out by means of an indirect optimization procedure, which is based on the theory of optimal control. The orbit peculiarities require that several perturbations are taken into account: an 8 × 8 model of the Earth potential is adopted and gravitational perturbations from Moon and Sun together with solar radiation pressure are considered. A procedure to guarantee convergence and define the optimal switching structure is outlined. Results concerning missions with up to 4.5 revolutions around the Earth are given, and significant features of this kind of deployment are highlighted. 1. Introduction Space trajectory optimization has gained importance thanks to the development of digital computers and the demanding features of space missions that are currently envisaged. Payload maximization is fundamental to ensure mission feasibility and to reduce costs; sometimes, flight-time minimization is sought to comply with operational requirements. Numerical methods for trajectory optimization can be in general classified into three main groups: indirect methods, direct methods, and evolutionary algorithms. The last group is receiving a great attention, as these algorithms are intrinsically apt to multidisciplinary and multiobjective optimization and in principle are capable of achieving the global optimum in a very large search space. When low-thrust trajectories are considered, evolutionary algorithms typically rely on approximations to maintain the computational time at reasonable values, as a large number of evaluations are required to achieve the solution; for these reasons, they usually provide only an estimate of the optimal solution and a refinement is required to obtain the optimum; direct methods are often used for this purpose. As a consequence, low-thrust trajectories are often dealt with by either direct or indirect methods that typically perform single-objective optimization, attaining a local optimum close to a tentative solution; additional effort is necessary to assure the achievement of the global optimum. An accurate comparison of direct and indirect methods is found in Betts [1]. A wide number of similarities between the methods is highlighted. Direct methods introduce a parametric representation of the control and/or state variables; the large number of variables, which are required to accurately describe the problem, usually leads to long computational times that can be reduced by taking the matrix sparsity into account. Indirect
Genus Pouteria: chemistry and biological activity
Silva, Cíntia A. M.;Simeoni, Luiz A.;Silveira, Damaris;
Revista Brasileira de Farmacognosia , 2009, DOI: 10.1590/S0102-695X2009000300025
Abstract: the genus pouteria belongs to the family sapotaceae and can be widely found around the world. these plants have been used as building material, as food, because the eatable fruits, as well as remedies in folk medicine. some biological activities have been reported to species of this genus such as antioxidant, anti-inflammatory, antibacterial and antifungal. however, the real potential of this genus as source of new drugs or phytomedicines remains unknown. therefore, a review of the so far known chemical composition and biological activities of this genus is presented to stimulate new studies about the species already reported moreover that species have no reference about chemistry or biological activities could be found until now.
Wideband, Multiband, Tunable, and Smart Antenna Systems for Mobile and UWB Wireless Applications
Renato Cicchetti,Antonio Faraone,Diego Caratelli,Massimiliano Simeoni
International Journal of Antennas and Propagation , 2013, DOI: 10.1155/2013/254807
Analytical and numerical investigation of traveling waves for the Allen-Cahn model with relaxation
Corrado Lattanzio,Corrado Mascia,Ramon G. Plaza,Chiara Simeoni
Mathematics , 2014,
Abstract: A modification of the parabolic Allen-Cahn equation, determined by the substitution of Fick's diffusion law with a relaxation relation of Cattaneo-Maxwell type, is considered. The analysis concentrates on traveling fronts connecting the two stable states of the model, investigating both the aspects of existence and stability. The main contribution is the proof of the nonlinear stability of the wave, as a consequence of detailed spectral and linearized analyses. In addition, numerical studies are performed in order to determine the propagation speed, to compare it to the speed for the parabolic case, and to explore the dynamics of large perturbations of the front.
A chemotactic model for interaction of antagonistic microflora colonies: front asymptotics and numerical simulations
Carlos Malaga,Antonmaria Minzoni,Ramon G. Plaza,Chiara Simeoni
Quantitative Biology , 2011,
Abstract: This paper studies a two-dimensional chemotactic model for two species in which one of them produces a chemo-repellent for the other. It is shown asymptotically and numerically how the chemical inhibits the invasion of a moving front for the second species and how stable steady states, which depend on the chemical concentration, can be reached. The results qualitatively explain experimental observations by Swain and Ray (Microbiol. Res. 164(2), 2009), where colonies of bacteria produce metabolite agents which prevent the invasion of fungi.
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