Coercivity and stability results for an extended Navier-Stokes system

In this article we study a system of equations that is known to {\em extend} Navier-Stokes dynamics in a well-posed manner to velocity fields that are not necessarily divergence-free. Our aim is to contribute to an understanding of the role of divergence and pressure in developing energy estimates capable of controlling the nonlinear terms. We address questions of global existence and stability in bounded domains with no-slip boundary conditions. Even in two space dimensions, global existence is open in general, and remains so, primarily due to the lack of a self-contained $L^2$ energy estimate. However, through use of new $H^1$ coercivity estimates for the linear equations, we establish a number of global existence and stability results, including results for small divergence and a time-discrete scheme. We also prove global existence in 2D for any initial data, provided sufficient divergence damping is included.Comment: 29 pages, no figure

Algebro-Geometric Solutions of the Boussinesq Hierarchy

We continue a recently developed systematic approach to the Bousinesq (Bsq) hierarchy and its algebro-geometric solutions. Our formalism includes a recursive construction of Lax pairs and establishes associated Burchnall-Chaundy curves, Baker-Akhiezer functions and Dubrovin-type equations for analogs of Dirichlet and Neumann divisors. The principal aim of this paper is a detailed theta function representation of all algebro-geometric quasi-periodic solutions and related quantities of the Bsq hierarchy.Comment: LaTeX, 48 page

The scaling attractor and ultimate dynamics for Smoluchowski's coagulation equations

We describe a basic framework for studying dynamic scaling that has roots in dynamical systems and probability theory. Within this framework, we study Smoluchowski's coagulation equation for the three simplest rate kernels $K(x,y)=2$, $x+y$ and $xy$. In another work, we classified all self-similar solutions and all universality classes (domains of attraction) for scaling limits under weak convergence (Comm. Pure Appl. Math 57 (2004)1197-1232). Here we add to this a complete description of the set of all limit points of solutions modulo scaling (the scaling attractor) and the dynamics on this limit set (the ultimate dynamics). The main tool is Bertoin's L\'{e}vy-Khintchine representation formula for eternal solutions of Smoluchowski's equation (Adv. Appl. Prob. 12 (2002) 547--64). This representation linearizes the dynamics on the scaling attractor, revealing these dynamics to be conjugate to a continuous dilation, and chaotic in a classical sense. Furthermore, our study of scaling limits explains how Smoluchowski dynamics ``compactifies'' in a natural way that accounts for clusters of zero and infinite size (dust and gel)

Totalitarismo

En 1951 Hannah Arendt publica Los orígenes del totalitarismo que, a pesar de su carácter controvertido, se erigiría en una referencia ineludible entre los estudios políticos del totalitarismo, en la medida en que pretendía ofrecer "un modelo de las posibilidades políticas y peligros de su tiempo". Las dos primeras partes del libro reúnen artículos escritos por Arendt durante la guerra y publicados en diversas revistas norteamericanas hasta 1947; en tanto que la tercera parte, la escribió posteriormente, entre los años 1948 y 1949. Durante el lapso de estos años, el proyecto de Arendt sufrió una reorientación. En la primera mitad de la década del 40', Arendt no utilizaba el término "totalitarismo" sino que, siguiendo a Franz Neumann, se refería al "imperialismo racial", mientras que recién en 1947 parece haber comenzado a concebir la tercera parte del libro abocada al análisis de los regímenes totalitarios. Trataremos de esclarecer las razones por las que Arendt se decide finalmente a estructurar todo su libro en torno del concepto de totalitarismo.Facultad de Humanidades y Ciencias de la Educació

Totalitarismo

En 1951 Hannah Arendt publica Los orígenes del totalitarismo que, a pesar de su carácter controvertido, se erigiría en una referencia ineludible entre los estudios políticos del totalitarismo, en la medida en que pretendía ofrecer "un modelo de las posibilidades políticas y peligros de su tiempo". Las dos primeras partes del libro reúnen artículos escritos por Arendt durante la guerra y publicados en diversas revistas norteamericanas hasta 1947; en tanto que la tercera parte, la escribió posteriormente, entre los años 1948 y 1949. Durante el lapso de estos años, el proyecto de Arendt sufrió una reorientación. En la primera mitad de la década del 40', Arendt no utilizaba el término "totalitarismo" sino que, siguiendo a Franz Neumann, se refería al "imperialismo racial", mientras que recién en 1947 parece haber comenzado a concebir la tercera parte del libro abocada al análisis de los regímenes totalitarios. Trataremos de esclarecer las razones por las que Arendt se decide finalmente a estructurar todo su libro en torno del concepto de totalitarismo.Facultad de Humanidades y Ciencias de la Educació

Perceptions and evaluations of front-line health workers regarding the Brazilian National Program for Improving Access and Quality to Primary Care (PMAQ): a mixed-method approach

Although it is well known that a successful implementation depends on the front-liners’ knowledge and participation, as well as on the organizational capacity of the institutions involved, we still know little about how front-line health workers have been involved in the implementation of the Brazilian National Program for Improving Access and Quality to Primary Care (PMAQ). This paper develops a contingent mixed-method approach to explore the perceptions of front-line health workers - managers, nurses, community health workers, and doctors - regarding the PMAQ (2nd round), and their evaluations concerning health unit organizational capacity. The research is guided by three relevant inter-related concepts from implementation theory: policy knowledge, participation, and organizational capacity. One hundred and twenty-seven health workers from 12 primary health care units in Goiânia, Goiás State, Brazil, answered semi-structured questionnaires, seeking to collect data on reasons for adherence, forms of participation, perceived impact (open-ended questions), and evaluation of organizational capacity (score between 0-10). Content analyses of qualitative data enabled us to categorize the variables “level of perceived impact of PMAQ” and “reasons for adhering to PMAQ”. The calculation and aggregation of the means for the scores given for organizational capacity enabled us to classify distinct levels of organizational capacity. We finally integrated both variables (Perceived-Impact and Organizational-Capacity) through cross-tabulation and the narrative. Results show that nurses are the main type of professional participating. The low organizational capacity and little policy knowledge affected workers participation in and their perceptions of the PMAQ

Blocking IL-17: A Promising Strategy in the Treatment of Systemic Rheumatic Diseases

Systemic rheumatic diseases are a heterogeneous group of autoimmune disorders that affect the connective tissue, characterized by the involvement of multiple organs, leading to disability, organ failure and premature mortality. Despite the advances in recent years, the therapeutic options for these diseases are still limited and some patients do not respond to the current treatments. Interleukin-17 (IL-17) is a cytokine essential in the defense against extracellular bacteria and fungi. Disruption of IL-17 homeostasis has been associated with the development and progression of rheumatic diseases, and the approval of different biological therapies targeting IL-17 for the treatment of psoriatic arthritis (PsA) and ankylosing spondylitis (AS) has highlighted the key role of this cytokine. IL-17 has been also implicated in the pathogenesis of systemic rheumatic diseases, including systemic lupus erythematosus (SLE), Sjogren's syndrome (SS) and systemic sclerosis (SSc). The aim of this review is to summarize and discuss the most recent findings about the pathogenic role of IL-17 in systemic rheumatic and its potential use as a therapeutic option

Renal Artery Angioplasty

Efectuámos angioplastia transiuminal percutânea (ATP) da artéria renal em 59 doentes hipertensos e houve benefício inicial na tensão arterial em 91,5% e tardio em 79,6%. Obtivemos melhores resultados nas lesões unilaterais (81,4%) do que nas bilaterais (72,7%); nas lesões fora do ostium (82,5%) do que nas do ostium (7 1,4%); nas lesões de origem fibromuscular (88,9%) do que nas de origem aterosclerótica(75%); e nos doentes com idade igual ou inferior a 55 anos (84,8%) do que em doentes com idade superior (71,4%). Estas diferenças não foram contudo significativas. Os bons resultados da ATP da artéria renal na hipertensão renovascular levam-nos a considerar esta forma de intervenção como uma alternativa do seu tratamento

Stability of a Nonequilibrium Interface in a Driven Phase Segregating System

We investigate the dynamics of a nonequilibrium interface between coexisting phases in a system described by a Cahn-Hilliard equation with an additional driving term. By means of a matched asymptotic expansion we derive equations for the interface motion. A linear stability analysis of these equations results in a condition for the stability of a flat interface. We find that the stability properties of a flat interface depend on the structure of the driving term in the original equation.Comment: 14 pages Latex, 1 postscript-figur

A dimension-breaking phenomenon for water waves with weak surface tension

It is well known that the water-wave problem with weak surface tension has small-amplitude line solitary-wave solutions which to leading order are described by the nonlinear Schr\"odinger equation. The present paper contains an existence theory for three-dimensional periodically modulated solitary-wave solutions which have a solitary-wave profile in the direction of propagation and are periodic in the transverse direction; they emanate from the line solitary waves in a dimension-breaking bifurcation. In addition, it is shown that the line solitary waves are linearly unstable to long-wavelength transverse perturbations. The key to these results is a formulation of the water wave problem as an evolutionary system in which the transverse horizontal variable plays the role of time, a careful study of the purely imaginary spectrum of the operator obtained by linearising the evolutionary system at a line solitary wave, and an application of an infinite-dimensional version of the classical Lyapunov centre theorem.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s00205-015-0941-