A potential missile guidance law based-on chaos

An important field of research in defense-related technology is the design of guidance laws. A guided missile is generally challenging to intercept if its trajectory becomes unpredictable. In this short communication, we have discussed a possible application of the chaos theory in developing an advanced guided missile, where the guidance law is based upon a robust chaotic map. This type of guided missile may be almost impossible to intercept by existing missile defense systems due to its unpredictable trajectory

Exploring classically chaotic potentials with a matter wave quantum probe

We study an experimental setup in which a quantum probe, provided by a quasi-monomode guided atom laser, interacts with a static localized attractive potential whose characteristic parameters are tunable. In this system, classical mechanics predicts a transition from a regular to a chaotic behavior as a result of the coupling between the longitudinal and transverse degrees of freedom. Our experimental results display a clear signature of this transition. On the basis of extensive numerical simulations, we discuss the quantum versus classical physics predictions in this context. This system opens new possibilities for investigating quantum scattering, provides a new testing ground for classical and quantum chaos and enables to revisit the quantum-classical correspondence

Effects of inflation expectations on macroeconomic dynamics: Extrapolative versus regressive expectations

In this paper we integrate heterogeneous inflation expectations into a simple monetary model. Guided by empirical evidence we assume that boundedly rational agents, selecting between extrapolative and regressive forecasting rules to predict the future inflation rate, prefer rules that have produced low prediction errors in the past. We show that integrating this behavioral expectation formation process into the monetary model leads to the possibility of endogenous macroeconomic dynamics. For instance, our model replicates certain empirical regularities such as irregular growth cycles or inflation persistence. Moreover, we observe multi-stability via a Chenciner bifurcation. --Extrapolative and regressive expectations,dynamic predictor selection,macroeconomic dynamics,nonlinearities and chaos,bifurcation analysis

Rings and spirals in barred galaxies. III. Further comparisons and links to observations

In a series of papers, we propose a theory to explain the formation and properties of rings and spirals in barred galaxies. The building blocks of these structures are orbits guided by the manifolds emanating from the unstable Lagrangian points located near the ends of the bar. In this paper, the last of the series, we present more comparisons of our theoretical results to observations and also give new predictions for further comparisons. Our theory provides the right building blocks for the rectangular-like bar outline and for ansae. We consider how our results can be used to give estimates for the pattern speed values, as well as their effect on abundance gradients in barred galaxies. We present the kinematics along the manifold loci, to allow comparisons with the observed kinematics along the ring and spiral loci. We consider gaseous arms and their relations to stellar ones. We discuss several theoretical aspects and stress that the orbits that constitute the building blocks of the spirals and rings are chaotic. They are, nevertheless, spatially well confined by the manifolds and are thus able to outline the relevant structures. Such chaos can be termed `confined chaos' and can play a very important role in understanding the formation and evolution of galaxy structures and in galactic dynamics in general. This work, in agreement with several others, argues convincingly that galactic dynamic studies should not be limited to the study of regular motions and orbits.Comment: 17 pages, 12 figures; accepted in MNRA

Selective amplification of scars in a chaotic optical fiber

In this letter we propose an original mechanism to select scar modes through coherent gain amplification in a multimode D-shaped fiber. More precisely, we numerically demonstrate how scar modes can be amplified by positioning a gain region in the vicinity of specific points of a short periodic orbit known to give rise to scar modes

Guided Imagery: A Technique to Benefit Youth at Risk

Guided imagery is a valuable intervention strategy that can benefit children who are at risk for social, academic, and mental health problems. Guided imagery is a technique that employs imagination, emotions, and a spectrum of bodily senses (Naparstek, 1994). This particular technique can be applied in community and academic settings to help enhance self-efficacy and mental health functioning for youth at risk. The need to implement creative interventions for youth can be overlooked by the chaos of poverty and social problems in vulnerable communities. Many schools and community agencies carry the burden of managing daily crises with few resources. This article is a call to action for effective mental health prevention treatment for youth at risk with a focus on guided imagery techniques that enhance creativity and positive visualization. This article presents an overview of mental health needs of vulnerable children, including those living in poverty; an explanation of guided imagery strategies and efficacy studies; and recommendations for the use of guided imagery interventions in academic and community youth settings