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Two glacier avalanches from Mount Huascarán killed 4,000 people and destroyed the town of Ranrahirca and killed 15,000 people and devastated the city of Yungay in 1970, making it the most deadly glacier disaster in world history. Because these avalanches were unpredictable and uncontrollable, the Peruvian government tried more forcefully than it had during previous decades to implement hazard zoning to reduce disaster vulnerability in the Callejón de Huaylas. Local residents with different risk perceptions, however, successfully resisted zoning plans. In the process, glacier and glacial lake science became contested knowledge that various social groups sought to control. Ironically, locals opposed zoning to limit state intervention in their communities. But by inhabiting hazard zones they ultimately became even more dependent on state programs to monitor Cordillera Blanca glaciers and drain glacial lakes. As glacier experts tried to protect populations, they mediated between the centralized state and various local populations.

This chapter considers systems of interacting agents placed on networks. The agents — spins, oscillators, interacting individuals, etc. — occupy the nodes of networks and interact with each other through network links. In more complicated situations, these agents, in turn, influence their network substrates, and so the pair, a network and the system of agents, co-evolve. The chapter discusses unusual phenomena in these cooperative systems on complex networks. In particular, the Ising model on networks is considered, various synchronization phenomena, and basic game theory models. Finally, avalanches and other abrupt phenomena in many-particle systems on complex networks are touched upon.

This chapter begins with a survey of early experimental results — the Planck spectrum, the photoelectric effect, and Compton scattering — that are usually presented as evidence for the existence of photons. The photon concept is indeed sufficient to explain these results, but it is not necessary. There are semi-classical models that explain the same data without introducing photons. The crucial experiment, in which light consisting of a single photon reflects from a beam splitter, depends on the essential indivisibility of photons, and it excludes all semi-classical descriptions of light. This discussion is followed by a preview of modern methods of production and detection of individual photons, e.g., spontaneous down conversion and Silicon avalanche-photodiode counters, together with an introduction to the quantum theory of light based on the correspondence principle.

This chapter first discusses which parameters determine sensor sensitivity, and then explains the basic semiconductor physics relevant to radiation detectors. Statistical limits to energy resolution are discussed with a simple derivation of the Fano factor. Semiconductor doping and pn-junctions are explained and applied to the formation of extended detector volumes. Quantitative expressions describing charge transport and collection times are derived. The mechanism of induced charge is explained and applied to multi-electrode structures, such as strip and pixel detectors (Ramo's theorem). Charge collection in the presence of trapping and alternate sensor materials is discussed. Avalanche gain is described and applied to photodiodes. The second half of the chapter explains the basics of electronic signal acquisition with voltage, current, or charge-sensitive amplifiers. The relationship between pulse rise time and frequency response is explained together with the basic amplifier parameters that limit bandwidth. In closing, the importance of amplifier input impedance is shown.

This chapter discusses the montane and subalpine coniferous forests and other vegetation of the Sierra Nevada and Cascade Ranges in California, vegetation patterns and environmental factors that affect distribution, and the role fire in spatial pattern and landscape. It also discusses some of the factors affecting vegetation, such as insects and pathogens, wind and avalanches, invasive species, air pollution, and logging.

This chapter discusses the occurrence of natural disturbances and their significant effects on the forests. It focuses on two disturbances that are the most important and widespread occurrences in the Klamaths: fire and water. The chapter first discusses the fire histories of the Klamath Mountains and interactions of various species and their adaptations to fire. It examines the effects of twentieth-century fire exclusion, the loss of fire-tolerant trees due to selective harvest, and plantation forestry. The chapter then discusses the negative and positive effects of floods on forests. It also describes other disturbances such as insects, pathogens, strong winds, drought, snow avalanches, and earthquakes.

This book investigates complex systems that are idealizations of naturally occurring phenomena characterized by the autonomous generation of structures and patterns at macroscopic scales. It provides material and guidance to allow the reader to learn about complexity through hands-on experimentation with complex systems with the aid of computer programs. Each chapter thus presents a simple computational model of natural complex phenomena ranging from avalanches and earthquakes to solar flares, epidemics, and ant colonies. This introductory chapter explains what complexity is, with emphasis on the fact that defining it is not a simple endeavor, and that it is not the same as randomness or chaos. It also shows that open dissipative systems are complex and clarifies what natural complexity means. Finally, it describes the computer programs listed in this book and suggests materials for further reading about complexity.

This chapter describes a simple computational idealization of a sandpile. When sand trickles slowly through your fingers, a small conical pile of sand forms below your hand. Sand avalanches of various sizes intermittently slide down the slope of the pile, which is growing both in width and in height but maintains the same slope angle. The pile of sand is a classic example of self-organized criticality. The chapter first provides an overview of the sandpile model before discussing its numerical implementation and a representative simulation involving a small 100-node lattice. It then examines the invariant power-law behavior of avalanches and the self-organized criticality of a sandpile. The chapter includes exercises and further computational explorations, along with a suggested list of materials for further reading.

This chapter considers the occurrence of traffic jams in the flow of moving automobiles as an example of complex collective behavior emerging from the interactions of system elements. It begins with a discussion of the basic design principle of an automobile traffic model and the numerical implementation of the model using the Python code. It then describes a representative simulation involving an ensemble of 300 cars initially at rest and distributed randomly, with a mean spacing of 10 units. It also examines how the traffic jam model behaves, traffic jams as avalanches, and the self-organized criticality of car traffic. The chapter includes exercises and further computational explorations, along with a suggested list of materials for further reading.

The Missing Witnessis set in the Swiss alps and features a romance plot aborted by a jealous villain and saved by the servant Genevieve, the ‘missing witness’ of the title. It offers a wonderful example of an extended sensation scene involving not one, but two hand-to-hand fight scenes on a treacherous mountain pass, the first ending with the hero seeming to plunge to his death and the second with an avalanche engulfing the heroine and the stage. Unfortunately the play was hastily withdrawn when the actor playing Gustave, Mr. J. F. Stephenson, misjudged his ‘sensation leap’ and broke his leg only three weeks after its opening at the Alexandra Theatre in Liverpool. Here we follow the printed edition of the text as published by John and Robert Maxwell, Braddon’s husband and stepson.Aided by these familial arrangements Braddon had become adept at managing and maintaining control over her published work, so there was no need for her to engage with another theatrical publisher.

This chapter mainly discusses plastic flow in FCC crystals, where dislocations are intrinsically highly mobile, going from elementary dislocation mechanisms to dislocation microstructures and the mechanical response. Experimental aspects and the current state of the art in modelling are discussed. The elementary mechanisms are phonon drag, which governs free-flight velocities between obstacles, dislocation interactions and especially intersections and reactions, as well as cross-slip, which is a poorly known, complex and multiform core mechanisms. The formation of dislocation patterns and their properties have not been modelled convincingly until now. The strain-hardening stages are semi-quantitatively understood, except at very large strains, and are reasonably well described by dislocation-based continuous models. The recent discovery of intermittent flow and dislocation avalanches has triggered a lot of activity, and constitutes a breakthrough with many potential consequences.

This chapter characterizes the robustness of multiplex and multilayer networks using classical percolation, directed percolation and antagonistic percolation. Classical percolation determines whether a finite fraction of nodes of the multilayer networks are connected by any type of connection. Classical percolation can be affected by multiplexity since the degree correlations among different layers can modulate the robustness of the entire multilayer network. Directed percolation describes the propagation of a disease requiring cooperative infection from different layers of the multiplex network. It displays a rich phase diagram including both continuous and discontinuous phase transitions. Antagonist percolation on a duplex network describes the competition between two layers and can give rise to hysteresis loops corresponding to phases that either one layer or the other can percolate Avalanches generated by the generalized Sandpile Model and Watts–Strogatz Model are also discussed, emphasizing their relevance for studying the stability of power grids and financial systems.