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Resumen Introducción: La teleconsulta puede ser de utilidad para evitar exposición de pacientes y optimizar recursos y dirigir a los que se consideran prioridad para atención presencial. Objetivo: Valorar el grado de satisfacción de la atención por teleconsulta en el Servicio de Otorrinolaringología del Hospital de Clínicas, San Lorenzo, durante julio de 2020. Material y Método: Diseño observacional, descriptivo, corte transversal, retrospectivo, muestreo probabilístico aleatorio simple. Se realizó encuestas sobre la calidad de atención por teleconsulta. Resultados: Se contactó 86 pacientes, 78 participaron. Edad promedio 32,2 años, 58,97% mujeres. 73% era de zona urbana, 27% rural. Los motivos de consulta más frecuentes fueron obstrucción nasal, hipoacusia y molestia en garganta. Un 66,67% no requirió ayuda para la consulta. 74,35% evitó asistir al médico durante la pandemia, el 51,72% por prevención o miedo. El 51,28% refirió empeoramiento de su dolencia durante la cuarentena. Se registró un alto nivel de satisfacción de la atención (9,41 ± 1,3). Un 82% refirió que esta modalidad puede ser implementada como opción, aunque el 70,5% requirió consulta presencial. Conclusión: La mayoría de los pacientes se encontraba en rango etario económicamente activo. La mayor parte de los pacientes no necesitó ayuda para acceder a la teleconsulta, reflejando la facilidad de acceso a esta. La teleconsulta disminuyó la necesidad de consulta presencial, el grado de aceptación del sistema de teleconsulta es elevada, traducidos en los altos índices de satisfacción y aceptación de la modalidad.

A passively Q-switched laser produces regular pulses above threshold. Here we show that this type of laser, described by the Yamada model, exhibits excitability below threshold. There is a stable equilibrium, the off-solution, from which the system can be triggered by a sufficiently large, but small perturbation, to produce a single pulse after which it settles back to the off-solution. In order to study possible applications, such as pulse reshaping and clock recovery, we consider the reaction of the laser to a triggering input pulse. Furthermore, we demonstrate that when the laser is subjected to injected optical noise below threshold it reacts by producing a train of pulses, whose coherence is maximal and, equivalently, the normalized jitter is minimal for a particular noise level. This shows that the Yamada model with optically injected noise constitutes an example of all-optical coherence resonance.

The current lateral ground loads requirement, FAR25.495, for an aircraft during a high-speed turn, was written in the middle of the last century, when relatively small aircraft with tricycle landing gear arrangements started to emerge. This requirement is known to be conservative when applied to large modern passenger aircraft. Nonlinearities (such as tyre forces) have a significant effect at the edge of operating envelopes, placing a renewed interest on analysis methods that can classify the dynamics in these regions. In this paper we use continuation methods to assess the loads that can be generated for different aircraft configurations during high-speed turns, and compare the results to the original requirement. A comparison is made between test results from an FAA study and continuation results, where all the significant test data points are located within an envelope constructed from continuation analysis. Continuation methods therefore provide a conservative estimate of the maximum lateral load factors. These values are however less than the value prescribed in the regulation.

We consider the homoclinic bifurcation of the Lorenz system, where two primary periodic orbits of saddle type bifurcate from a symmetric pair of homoclinic loops. The two secondary equilibria of the Lorenz system remain the only attractors before and after this bifurcation, but a chaotic saddle is created in a tubular neighbourhood of the two homoclinic loops. This invariant hyperbolic set gives rise to preturbulence, which is characterised by the presence of arbitrarily long transients. In this paper we show how and where preturbulence arises in the three-dimensional phase space. To this end, we consider how the relevant two-dimensional invariant manifolds --- the stable manifolds of the origin and of the primary periodic orbits --- organise the phase space of the Lorenz system. More specifically, by means of recently developed and very robust numerical methods, we study how these manifolds intersect a suitable sphere in phase space. In this way, we show how the basins of attraction of the two attracting equilibria change topologically in the homoclinic bifurcation. More specifically, we characterise preturbulence in terms of the accessible boundary between the two basins, which accumulate on each other in a Cantor structure.

This paper presents a case study of a semiconductor laser with a saturable absorber (SLSA) and an external optical feedback loop. The system is modeled by the Yamada rate equations to which a feedback term has been added. Starting from the bifurcation analysis of the SLSA alone, the influence of feedback strength and delay time is investigated by means of a numerical bifurcation analysis. The emphasis is on excitable dynamics and self-sustained oscillations in the presence of the feedback loop.

This paper presents a study of how different vibration modes contribute to the dynamics of an inclined cable that is parametrically excited close to a 2 : 1 internal resonance. The behaviour of inclined cables is important for the design and analysis of cable-stay bridges. In this work the cable vibrations are modelled by a four-mode model. This type of model has been used previously to study the onset of cable sway motion caused by internal resonances which occur due to the nonlinear modal coupling terms. A bifurcation study is carried out with numerical continuation techniques applied to the scaled and averaged modal equations. As part of this analysis, the amplitudes of the cable vibration response to support inputs is computed. These theoretical results are compared with experimental measurements taken from a 5.4 m long inclined cable with a vertical support input at the lower end. In general this comparison shows a very high level of agreement.

Recent studies suggest that fuel savings can be realised if more efficient surface movements can be achieved through means other than the engines of an aircraft, or by optimising the scheduling of aircraft on the ground. All aspects of ground manoeuvring therefore need to be studied to understand the impact of such changes. This paper presents an analysis method for medium-speed manoeuvres, and, more specifically, runway exit manoeuvres. Kinematic equations that were derived for towing analysis form the basis of the runway exit study, from which empirical formulas are derived for steering angle and clearance predictions. The results of the empirical method compare very well with kinematic studies, as well as detailed dynamic model simulations, as is demonstrated with the test case example of an A380 model. The empirical formulas can be used to great effect during the early design phases of an aircraft programme for the prediction of steering angles and clearance distances, when very little data is available. The greatest advantage of the proposed method is that any aircraft configuration or runway exit can be analysed.

This paper presents a study of how different vibration modes contribute to the dynamics of an inclined cable that is parametrically excited close to a 2:1 internal resonance. The behaviour of inclined cables is important for the design and analysis of cable-stay bridges. In this work the cable vibrations are modelled by a four-mode model. This type of model has been used previously to study the onset of cable sway motion caused by internal resonances which occur due to the nonlinear modal coupling terms. A bifurcation study is carried out with numerical continuation techniques applied to the scaled and averaged modal equations. As part of this analysis, the amplitudes of the cable vibration response to support inputs is computed. These theoretical results are compared with experimental measurements taken from a 5.4 m long inclined cable with a vertical support input at the lower end. In general this comparison shows a very high level of agreement.

Mixed-mode oscillations (MMOs) are trajectories of a dynamical system in which there is an alternation between oscillations of distinct large and small amplitudes. MMOs have been observed and studied for over thirty years in chemical, physical and biological systems. Few attempts have been made thus far to classify different patterns of MMOs, in contrast to the classification of the related phenomena of bursting oscillations. This paper gives a survey of different types of MMOs, concentrating its analysis on MMOs whose small-amplitude oscillations are produced by a local, multiple-time-scale "mechanism." Recent work gives substantially improved insight into the mathematical properties of these mechanisms. In this survey, we unify diverse observations about MMOs and establish a systematic framework for studying their properties. Numerical methods for computing different types of invariant manifolds and their intersections are an important aspect of the analysis described in this paper.

The loss of lateral stability of an aircraft turning on the ground is associated with a rapid transition from small-amplitude oscillations to large-amplitude relaxation oscillations over a very small parameter range. This phenomenon is shown to be associated with a canard explosion in an industry-tested model of aircraft ground dynamics, where the longitudinal velocity of the aircraft acts as a slow variable of the system. The associated family of canard orbits is identified and the canard explosion is shown to be directly related to the successive saturation of tyre forces at the two main landing gears. We present a canonical two-dimensional slow-fast vector field model that captures the key features of this type of canard explosion; it differs from the canard explosion in the archetypal Van der Pol system in terms of the shape of the associated critical manifold.

The stability of two semiconductor lasers that are spatially separated by a passive resonator is analysed using the composite-cavity mode approach. We study the nonlinear interactions of three composite-cavity modes and identify regions of in-phase and out-of-phase laser locking in the parameter plane of the transmission coe cients of the coupling mirrors and the laser length di erence. Bifurcation analysis shows that the structure of the locking regions strongly depends on (i) the length of the passive resonator and (ii) the amount of amplitude-phase coupling of the laser field. Specifically, we find a single locking region when the passive resonator and the lasers have comparable lengths and up to three separate locking regions when the passive resonator is much shorter than the lasers. Furthermore, we use the recently developed 0-1 test for chaos to uncover intricate regions of chaotic dynamics that shrink in size and eventually disappear as the passive resonator length becomes comparable to the laser length.

We present a general approach to assess an aircraft's performance during taxiway manoeuvres across the range of its operation. The main motivation for this work is to evaluate the suitability of the existing Federal Aviation Regulation for lateral loads experienced during turning manoeuvres. To this end, operating regions are defined in terms of parameters specifying the approach velocity and steering input for a generic turn that is representative of pilot practice. The limits of the operating regions represent the extremes of the aircraft's operation during turning as determined by the maximal lateral loading conditions identified in published studies of instrumented in-service passenger aircraft. The performance of the turn can be assessed over the entire operational range in terms of the actual loads experienced at individual landing gears. Recent studies by the Federal Aviation Administration of instrumented aircraft have been limited to investigating the lateral loads experienced at the aircraft's CG position. Our results show that this information is insufficient to predict the actual loads experienced by individual landing gears, especially for the nose gear which is found to experience considerably higher lateral loads than predicted by the corresponding loads at CG. We find a robustness in the results with respect to changes in the aircraft's mass and the criterion used to define the limits of the operating regions.