Border Collision Route to Quasiperiodicity: Numerical Investigation and Experimental Confirmation

Numerical studies of higher-dimensional piecewise-smooth systems have recently shown how a torus can arise from a periodic cycle through a special type of border-collision bifurcation. The present article investigates this new route to quasiperiodicity in the two-dimensional piecewise-linear normal form map. We have obtained the chart of the dynamical modes for this map and showed that border-collision bifurcations can lead to the birth of a stable closed invariant curve associated with quasiperiodic or periodic dynamics. In the parameter regions leading to the existence of an invariant closed curve, there may be transitions between an ergodic torus and a resonance torus, but the mechanism of creation for the resonance tongues is distinctly different from that observed in smooth maps. The transition from a stable focus point to a resonance torus may lead directly to a new focus of higher periodicity, e.g., a period-5 focus. This article also contains a discussion of torus destruction via a homoclinic bifurcation in the piecewise-linear normal map. Using a dc-dc converter with two-level control as an example, we report the first experimental verification of the direct transition to quasiperiodicity through a border-collision bifurcation

Attitudes Toward Euthanasia Among Doctors in a Tertiary Care Hospital in South India: A Cross Sectional study

Context: Advances in expertise and equipment have enabled the medical profession to exercise more control over the processes of life and death, creating a number of moral and ethical dilemmas. People may live for extended periods with chronic painful or debilitating conditions that may be incurable. Aim: This study attempts to study the attitudes of doctors toward euthanasia and the possible factors responsible for these attitudes. Settings and Design: A cross-sectional survey of 213 doctors working at a tertiary care hospital was conducted to determine their attitudes toward euthanasia. Materials and Methods: A self-administered questionnaire was used to assess attitudes and personal perceptions about euthanasia. Statistical Analysis Used: The Chi square test was used to assess factors influencing attitudes toward euthanasia. Results: A majority of the respondents (69.3%) supported the concept of euthanasia. Relief from unbearable pain and suffering was the most commonly (80.3%) cited reason for being willing to consider the option of euthanasia. Majority of those who were against euthanasia (66.2%) felt that the freedom to perform euthanasia could easily be misused. Disapproval of euthanasia was associated with religious affiliation (P<0.001) and speciality (P<0.001). Conclusions: A majority of the doctors in this study supported euthanasia for the relief of unbearable pain and suffering. Religion and speciality appear to be significant in determining attitudes toward euthanasia

Fabrication And Characterisation of Bandgap Tuned Lasers in GaAs/AlGaAs Quantum Well Structures Using Pulsed Laser

We report the use of Q-switched Nd:YAG laser irradiation technique to enhance the interdiffusion of Ga-Al, and hence the quantum well intermixing (QWI), in GaAs/AlGaAs double quantum well (DQW) structures. Multiphoton interactions with carriers lead to phonon emission; the phonons interact with lattice thus generating point defects, which diffuse during subsequent annealing stage in a rapid thermal processor (RTP) and cause intermixing. This QWI technique is essentially impurity free and potentially high resolution. 3µm wide ridge waveguide lasers were fabricated from the intermixed and control samples. A differential bandgap shift of up to 40meV have been observed between the intermixed and the as-grown lasers. Parameters, such as threshold current density, internal quantum efficiency, material loss, and transparency current density were extracted from the light-current (L-I) characteristics of the lasers cleaved to different cavity lengths. Compared to as-grown devices, it was found that the bandgap tuned lasers exhibited a small increase in the threshold current density, and negligible change in the slope efficiency

Content Delivery Networks: State of the Art, Trends, and Future Roadmap

Recently, Content Delivery Networks (CDN) have become more and more popular. The technology itself is ahead of academic research in this area. Several dimensions of the technology have not been adequately investigated by academia. These dimensions include outline management, security, and standardization. Discovering and highlighting aspects of this technology that may have or have not been covered by academic research is the first step toward helping academia bridge the gap with industry or even go one step further to lead industry in the right direction. This suggests a comprehensive survey on research works in this regard. The literature in this area has already come up with some surveys and taxonomies, but some of them are outdated or do not cover every aspect of CDN while others fail to detect existing trends or to develop a holistic roadmap for research on the technology. Furthermore, none of the existing surveys aim at enlightening the dark aspects of the technology that have not been subject to academic research. In this survey, we first extract the lifecycle of a CDN as suggested by the existing research. Then, we investigate previous relevant works on each phase of the lifecycle to clarify where the research is currently located and headed. We show how CDN technology tends to converge with emerging paradigms such as cloud computing, edge computing, and machine learning, which are more mature in terms of academic research. This helps us determine the right direction for further research by revealing the deficiencies in existing works