ABSTRACT
Combined effects of the damping and forcing in the underdamped time-delayed Duffing oscillator are considered in this paper. We analyse the generation of a certain damping-induced unpredictability due to the gradual suppression of interwell oscillations. We find the minimal amount of the forcing amplitude and the right forcing frequency to revert the effect of the dissipation, so that the interwell oscillations can be restored, for different time delay values. This is achieved by using the delay-induced resonance, in which the time delay replaces one of the two periodic forcings present in the vibrational resonance. A discussion in terms of the time delay of the critical values of the forcing for which the delay-induced resonance can tame the dissipation effect is finally carried out. This article is part of the theme issue 'Vibrational and stochastic resonance in driven nonlinear systems (part 1)'.
ABSTRACT
We use the Hénon-Heiles system as a paradigmatic model for chaotic scattering to study the Lorentz factor effects on its transient chaotic dynamics. In particular, we focus on how time dilation occurs within the scattering region by measuring the time with a clock attached to the particle. We observe that the several events of time dilation that the particle undergoes exhibit sensitivity to the initial conditions. However, the structure of the singularities appearing in the escape time function remains invariant under coordinate transformations. This occurs because the singularities are closely related to the chaotic saddle. We then demonstrate using a Cantor-like set approach that the fractal dimension of the escape time function is relativistic invariant. In order to verify this result, we compute by means of the uncertainty dimension algorithm the fractal dimensions of the escape time functions as measured with an inertial frame and a frame comoving with the particle. We conclude that, from a mathematical point of view, chaotic transient phenomena are equally predictable in any reference frame and that transient chaos is coordinate invariant.
ABSTRACT
BACKGROUND: Stress and anxiety have frequently been mentioned as possible factors related to the development of oral lichen planus (OLP), although this association remains controversial. OBJECTIVE: To determine whether anxiety and depression constitute risk factors in the development of OLP. MATERIAL AND METHODS: Eighty patients diagnosed as having OLP were studied: anxiety was evaluated by the Hamilton Anxiety Scale and depression with the Montgomery-Asberg Depression Rating Scale. The results were contrasted with those obtained in a control series of the same number of subjects (n = 80) matched for age and sex. RESULTS: Significantly greater anxiety and depression were observed among patients with OLP than in the control group. Odds ratios of 2.8 and 4.4 were obtained for anxiety and depression, respectively. CONCLUSION: Our findings suggest that anxiety and depression constitute risk factors that could influence the development of OLP.
Subject(s)
Anxiety/complications , Depression/complications , Lichen Planus, Oral/psychology , Adolescent , Adult , Aged , Aged, 80 and over , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Odds Ratio , Regression Analysis , Risk FactorsABSTRACT
We present a comprehensive review of barodontalgia, with reference to the several pathogenetic hypotheses, and insisting on the consideration of barodontalgia in the differential diagnosis of toothache. The odontologists approach to this increasing clinical problem is also discussed.
Subject(s)
Aerospace Medicine , Barotrauma , Toothache/etiology , Aircraft , Dentin Permeability , HumansABSTRACT
It is reported a case of macroglossia with neoplasic-like ulcer in the tongue, in a patient with amyloidosis and hypothyroidism.
