Separatrix Reconnections in Chaotic Regimes

In this paper we extend the concept of separatrix reconnection into chaotic regimes. We show that even under chaotic conditions one can still understand abrupt jumps of diffusive-like processes in the relevant phase-space in terms of relatively smooth realignments of stable and unstable manifolds of unstable fixed points.Comment: 4 pages, 5 figures, submitted do Phys. Rev. E (1998

Natura y ratio en la especulación sobre el cosmos: Guillermo de Auxerre y Felipe el Canciller

The present study examines the Platonic, Stoic and Ciceronian antecedents in the expositions of William of Auxerre and Philip the Chancellor in their respective Summae, both of which make “ius naturale” to be the guiding principle of the practical-moral life, and which thus provides ontological and anthropological foundations. In addition, the author also investigates the meanings of the term “natura” in the Roman legal tradition, as it persisted at the beginnings of the 13th century; finally, she also considers its philosophical basis

Unidad y jerarquía cosmológica en la Summa de Bono de Felipe el Canciller

The present study examines, on one hand, Philip the Chancellor’s work in the early 13th century on the nature of being as good, in the context of the development of his philosophical method. It deals with his position on the value of philosophical propositions to the understanding of the faith. On the other hand, the study presents Philip’s cosmic-anthropological concepts, particularly stressing the contribution of Platonic, Aristotelian and Hellenistic traditions to it

Planos de racionalidad en el conocimiento de sí. Sinergia de tradiciones helenísticas en la "Summa aurea" de Guillermo de Auxerre

Este estudio aborda la elaboración de la Summa aurea de Guillermo de Auxerre (circa 1215-1229) sobre la naturaleza de la razón en su función directiva del obrar humano y la presencia de la racionalidad en la naturaleza del mundo en su conjunto. Con un propósito exegético-crítico, considera la sinergia de fuentes de tradición helenística con las procedentes de la tradición jurídicoromana y desarrollos agustinianos que Guillermo de Auxerre pone en cuestión.This paper considers arguments in the Summa aurea. of William of Auxerre (circa 1215-1229) concerning the nature of reason in its directive function of human action and the presence of rationality in the universe as a whole. From a critical-exegetic perspective, this study examines the synergy of Hellenistic sources with Roman legal teachings and developments of the Augustinian tradition that William of Auxerre questions calls into question

Nonintegrable Interaction of Ion-Acoustic and Electromagnetic Waves in a Plasma

In this paper we re-examine the one-dimensional interaction of electromagnetic and ion acoustic waves in a plasma. Our model is similar to one solved by Rao et al. (Phys. Fluids, vol. 26, 2488 (1983)) under a number of analytical approximations. Here we perform a numerical investigation to examine the stability of the model. We find that for slightly over dense plasmas, the propagation of stable solitary modes can occur in an adiabatic regime where the ion acoustic electric field potential is enslaved to the electromagnetic field of a laser. But if the laser intensity or plasma density increases or the laser frequency decreases, the adiabatic regime loses stability via a transition to chaos. New asymptotic states are attained when the adiabatic regime no longer exists. In these new states, the plasma becomes rarefied, and the laser field tends to behave like a vacuum field.Comment: 19 pages, REVTeX, 6 ps figures, accepted for publication in Phys. Rev.

Mathematical model for preoperative identification of obstructed nasal subsites

The planning of experimental studies for evaluation of nasal airflow is particularly challenging given the difficulty in obtaining objective measurements in vivo. Although standard rhinomanometry and acoustic rhinometry are the most widely used diagnostic tools for evaluation of nasal airflow, they provide only a global measurement of nasal dynamics, without temporal or spatial details. Furthermore, the numerical simulation of nasal airflow as computational fluid dynamics technology is not validated. Unfortunately, to date, there are no available diagnostic tools to objectively evaluate the geometry of the nasal cavities and to measure nasal resistance and the degree of nasal obstruction, which is of utmost importance for surgical planning. To overcame these limitations, we developed a mathematical model based on Bernoulli's equation, which allows clinicians to obtain, with the use of a particular direct digital manometry, pressure measurements over time to identify which nasal subsite is obstructed. To the best of our knowledge, this is the first study to identify two limiting curves, one below and one above an average representative curve, describing the time dependence of the gauge pressure inside a single nostril. These upper and lower curves enclosed an area into which the airflow pattern of healthy individuals falls. In our opinion, this model may be useful to study each nasal subsite and to objectively evaluate the geometry and resistances of the nasal cavities, particularly in preoperative planning and follow-up

Síndrome das pernas inquietas associada a insuficiência cardíaca e agravada após troca valvular : maldição de Vesper?

The restless legs syndrome (RLS) is a neurological disorder characterized by symptoms of discomfort (usually paresthesias) in the limbs, predominating in the afternoon, present mainly at rest and alleviated by movement. The symptoms usually appear in the late afternoon or at night, which may bring on a significant increase in sleep latency and contribute to poor sleep quality1. Since the prevalence of RLS increases with age2, heterogeneous conditions are likely to be identified in association with other illnesses typical of advanced age, making diagnoses more complex, and indicating the importance of studying these secondary forms, and their possible physiopathological mechanisms. We report a case of RLS associated to important abnormalities of the cardiac function in an elderly patient, who underwent several cardiac surgical interventions, and discuss the possible implications of this cardiac dysfunction in the etiology and maintenance of the motor symptoms. This case is reported after approval of our Institution and informed patient's consent

An outlier-resistant κ\kappa-generalized approach for robust physical parameter estimation

In this work we propose a robust methodology to mitigate the undesirable effects caused by outliers to generate reliable physical models. In this way, we formulate the inverse problems theory in the context of Kaniadakis statistical mechanics (or $\kappa$-statistics), in which the classical approach is a particular case. In this regard, the errors are assumed to be distributed according to a finite-variance $\kappa$-generalized Gaussian distribution. Based on the probabilistic maximum-likelihood method we derive a $\kappa$-objective function associated with the finite-variance $\kappa$-Gaussian distribution. To demonstrate our proposal's outlier-resistance, we analyze the robustness properties of the $\kappa$-objective function with help of the so-called influence function. In this regard, we discuss the role of the entropic index ($\kappa$) associated with the Kaniadakis $\kappa$-entropy in the effectiveness in inferring physical parameters by using strongly noisy data. In this way, we consider a classical geophysical data-inverse problem in two realistic circumstances, in which the first one refers to study the sensibility of our proposal to uncertainties in the input parameters, and the second is devoted to the inversion of a seismic data set contaminated by outliers. The results reveal an optimum $\kappa$-value at the limit $\kappa \rightarrow 2/3$, which is related to the best results.Comment: 37 pages, 23 figure