One-dimensional symmetry and Liouville type results for the fourth order Allen-Cahn equation in RN^N

In this paper, we prove an analogue of Gibbons' conjecture for the extended fourth order Allen-Cahn equation in R N , as well as Liouville type results for some solutions converging to the same value at infinity in a given direction. We also prove a priori bounds and further one-dimensional symmetry and rigidity results for semilinear fourth order elliptic equations with more general nonlinearities

Magnetic critical behavior of two-dimensional random-bond Potts ferromagnets in confined geometries

We present a numerical study of 2D random-bond Potts ferromagnets. The model is studied both below and above the critical value $Q_c=4$ which discriminates between second and first-order transitions in the pure system. Two geometries are considered, namely cylinders and square-shaped systems, and the critical behavior is investigated through conformal invariance techniques which were recently shown to be valid, even in the randomness-induced second-order phase transition regime Q>4. In the cylinder geometry, connectivity transfer matrix calculations provide a simple test to find the range of disorder amplitudes which is characteristic of the disordered fixed point. The scaling dimensions then follow from the exponential decay of correlations along the strip. Monte Carlo simulations of spin systems on the other hand are generally performed on systems of rectangular shape on the square lattice, but the data are then perturbed by strong surface effects. The conformal mapping of a semi-infinite system inside a square enables us to take into account boundary effects explicitly and leads to an accurate determination of the scaling dimensions. The techniques are applied to different values of Q in the range 3-64.Comment: LaTeX2e file with Revtex, revised versio

El fruto de la tecnología: debemos nosotros alimentar un paciente anciano a todo costo? Fruits of technology: should we feed an old patient at all costs?

El próposito de este artículo es analizar las preguntas que rodean un común pero complejo dilema ético, médico y asistencial, llamado la justificación de continuar o suspender la alimentación forzada en pacientes extremadamente ancianos que sufren de aguda demencia progresiva. Tradicionalmente el principio de santidad de la vida apoya la idea que la vida debe ser prolongada a todo costo y la decisión de continuar com la alimentación, no se pone en duda. Sin embargo, últimamente han surgido gran cantidad de ideas revolucionarias hacia las actitudes, las concepciones y los valores del tratamiento, los cuales han guiado hacia una urgente necesidad de discutir el problema en un sentido mas profundo. Hasta qué punto debemos alimentar a la fuerza un paciente demente, el cual se niega a comer (sonda, alimentación intravenosa), atando sus manos o utilizando otras medidas? Esto ocurrío en un instituto geriátrico en Israel, donde una orden médica de un determinado médico consterno a las enfermeras de planta, las cuales decidieron que en este específico caso su punto de vista no era similar al del médico. El resultado fue una conferencia nacional con la participación de médicos, enfermeras, trabajadores sociales y sicólogos.<br>The purpose of this article is to analyze questions on a complex ethic, medical and caring dilemma about reasons to continue or suspend compelled alimentation in really old patients carrying progressive acute dementia. Traditionally, the principle of life holiness supports the idea that life should be extended at all costs and the decision to continue feeding the patients is not questioned. However, revolutionary ideas are arising about attitudes, concepts and value of treatment, conducting an urgent need to discuss this problem deeply. Until when should we compel demented patients to eat, as they do not accept food and have to be fed through a catheter or intraveined alimentation, tying back their hands or using other measures? This discussion occurred in a geriatric institution at Israel, when a doctor's order was not accepted by nurses, as they had a different way of seeing the problem. A national conference on this theme was organized with the attendance of doctors, nurses, social workers and psychologists