Insights into oscillator network dynamics using a phase-isostable framework.

Networks of coupled nonlinear oscillators can display a wide range of emergent behaviors under the variation of the strength of the coupling. Network equations for pairs of coupled oscillators where the dynamics of each node is described by the evolution of its phase and slowest decaying isostable coordinate have previously been shown to capture bifurcations and dynamics of the network, which cannot be explained through standard phase reduction. An alternative framework using isostable coordinates to obtain higher-order phase reductions has also demonstrated a similar descriptive ability for two oscillators. In this work, we consider the phase-isostable network equations for an arbitrary but finite number of identical coupled oscillators, obtaining conditions required for the stability of phase-locked states including synchrony. For the mean-field complex Ginzburg-Landau equation where the solutions of the full system are known, we compare the accuracy of the phase-isostable network equations and higher-order phase reductions in capturing bifurcations of phase-locked states. We find the former to be the more accurate and, therefore, employ this to investigate the dynamics of globally linearly coupled networks of Morris-Lecar neuron models (both two and many nodes). We observe qualitative correspondence between results from numerical simulations of the full system and the phase-isostable description demonstrating that in both small and large networks, the phase-isostable framework is able to capture dynamics that the first-order phase description cannot.

Standing and travelling waves in a spherical brain model: The Nunez model revisited.

The Nunez model for the generation of electroencephalogram (EEG) signals is naturally described as a neural field model on a sphere with space-dependent delays. For simplicity, dynamical realisations of this model either as a damped wave equation or an integro-differential equation, have typically been studied in idealised one dimensional or planar settings. Here we revisit the original Nunez model to specifically address the role of spherical topology on spatio-temporal pattern generation. We do this using a mixture of Turing instability analysis, symmetric bifurcation theory, centre manifold reduction and direct simulations with a bespoke numerical scheme. In particular we examine standing and travelling wave solutions using normal form computation of primary and secondary bifurcations from a steady state. Interestingly, we observe spatio-temporal patterns which have counterparts seen in the EEG patterns of both epileptic and schizophrenic brain conditions.

Ernst Ferdinand Sauerbruch: rise and fall of the pioneer of thoracic surgery.

Ferdinand Sauerbruch (1875-1951) was a pioneer of thoracic and cardiac surgery and is undoubtedly one of the twentieth century's most outstanding surgeons. Before 1904 operations on the thorax met with fatal complications due to pneumothorax. Sauerbruch developed a pressure-differential chamber that maintained normal respiration and enabled safe operations to be undertaken on the thorax. Together with von Mikulicz, he initiated intrathoracic operations and later developed various surgical procedures on the mediastinum, lungs, pericardium, heart, and esophagus. The simple yet effective techniques of positive-pressure ventilation replaced the expensive, cumbersome negative-pressure chamber. Sauerbruch's latter years were marred by dementia that adversely affected his personality, intellect, and capacity as a surgeon. The unjustifiable toll of increasing patient morbidity and mortality forced authorities to dismiss him in 1949. He died at the age of 76 in Berlin. After almost a century since the advent of the first safe thoracic surgery, the advances in technique and technology have been enormous. A great deal is owed to the inspiration and contributions of Ferdinand Sauerbruch.

Revolution in Australian surgery, 1914-1994.

Between 1914 and 1994, Australian surgery has undergone a period of unique growth and scientific revolution. It has been influenced by the effects of two world wars, two lesser engagements in Asia (Korea and Vietnam) and vast developments and social changes in the Australian Commonwealth. The pioneer surgeon, whose background was general practice, has evolved into today's member of a scientifically orientated professional body which is responsible for its own standards, training and management.

Australian surgeons and society.

Surgery and society are living entities, forever changing and evolving. The quality of the men who served them will never change. In this brief sketch I have traced a lineage of men - men of good heart - men who have mastered their craft - men who have applied it in accordance with the ancient tradition of helping those in need - men who matched their times and the leaders of Australian society.

Melanotic neuroectodermal tumour of infancy arising in anterior fontanelle.

A case is described of a melanotic neuroectodermal tumour which developed in the anterior fontanelle of the skull of a Melanesian girl during the first 7 mth of life.