Modeling Phase Transitions in the Brain


Book Description

Foreword by Walter J. Freeman. The induction of unconsciousness using anesthetic agents demonstrates that the cerebral cortex can operate in two very different behavioral modes: alert and responsive vs. unaware and quiescent. But the states of wakefulness and sleep are not single-neuron properties---they emerge as bulk properties of cooperating populations of neurons, with the switchover between states being similar to the physical change of phase observed when water freezes or ice melts. Some brain-state transitions, such as sleep cycling, anesthetic induction, epileptic seizure, are obvious and detected readily with a few EEG electrodes; others, such as the emergence of gamma rhythms during cognition, or the ultra-slow BOLD rhythms of relaxed free-association, are much more subtle. The unifying theme of this book is the notion that all of these bulk changes in brain behavior can be treated as phase transitions between distinct brain states. Modeling Phase Transitions in the Brain contains chapter contributions from leading researchers who apply state-space methods, network models, and biophysically-motivated continuum approaches to investigate a range of neuroscientifically relevant problems that include analysis of nonstationary EEG time-series; network topologies that limit epileptic spreading; saddle--node bifurcations for anesthesia, sleep-cycling, and the wake--sleep switch; prediction of dynamical and noise-induced spatiotemporal instabilities underlying BOLD, alpha-, and gamma-band Hopf oscillations, gap-junction-moderated Turing structures, and Hopf-Turing interactions leading to cortical waves.




A Tale of the War


Book Description

Reproduction of the original: A Tale of the War by Henry F. Keenan




Structural Integrity of Aging Airplanes


Book Description

The emergence of civil aviation as a means of mass transportation is primarily due to the large scale construction of jet airplanes in the past 30 years or so. A large number of these jet airplanes is currently operating at or beyond their designed fatigue lives. Thus, the structural integrity of these aging airplanes has become an issue of major concern to all nations of the world. To bring the needed technical and research focus on the issues involved in the life-enhancement and safety-assurance of aging airplanes, the Federal Aviation Administration sponsored a symposium in Atlanta, GA, USA, during 20-22 March 1990. This symposium, under the title "International Symposium on Structural Integrity of Aging Airplanes· was organized jointly be the Georgia Institute of Technology (Center for Computational Mechanics) and the Transportation Systems Center (Cambridge, MA) of the U.S. Department of Transportation. Industrial and academic experts from several countries in North America, Europe and Asia, were invited to discuss their experiences and proposed solutions. This monograph contains the original papers that represent the expanded and edited versions of the talks presented at this symposium. This book aims to bring the collective experience, from across the world, with problems related to the structural integrity of aging airplanes to the attention of the professional and research community at large - in the hope that it may stimulate further fruitful research on this important topic of global concern.




Unsteady Transonic Flow


Book Description

This classic monograph on unsteady transonic flow — the flow of air encountered at speeds at or near the speed of sound — is of continuing interest to students and professionals in aerodynamics, fluid dynamics, and other areas of applied mathematics. After a brief Introduction, Swedish physicist Mårten T. Landahl presents a chapter in which the two-dimensional solution is derived, succeeded by a discussion of its relation to the subsonic and supersonic solutions. Three chapters on low aspect ratio configurations follow, covering triangular wings and similar planforms with curved leading edges, rectangular wings, and cropped delta wings, and low aspect ratio wing-body combinations. The treatment concludes with a consideration of the experimental determination of air forces on oscillating wings at transonic speeds.







Avian Urban Ecology


Book Description

This edited volume adopts an evolutionary framework to explore how pre-existing differences in life history, behaviour, and physiology of birds may determine the course of their adaptation to urban habitats.