In this chapter we examine the important topic of the flow of magma. Throughout Earth’s history, the rise of magmas toward the surface has differentiated the planet and created crustal rocks that are compositionally very different from the bulk Earth. The flow of magma has therefore played a critical role in the evolution of the planet.

Thermodynamics, the study of energy, is one of the most important subjects in all of science. Historically, it evolved from the desire to understand the efficiency of machines, in particular steam engines. Much of its terminology therefore centers around heat and work, especially work associated with expanding gas. Thermodynamics, however, deals with the transfer of other forms of energy as well, such as that associated with chemical reactions.

So far, we have dealt only with systems and minerals of fixed composition. Most of the common rock-forming minerals, however, belong to solid solution series in which compositions can vary widely. Magmas and intergranular solutions in metamorphic rocks are further examples of natural materials of variable composition. In addition, many natural systems are open; that is, material can be added or subtracted. Changes in composition bring about changes in energy. Thus, when systems strive for equilibrium, compositional adjustments must be made so as to minimize free energies.

We have learned that groups of people are ranked according to a variety of characteristics such as social class (Chapter 4), gender (Chapter 10), and race/ethnicity (Chapter 11) and that these distinctions often allow social scientists to predict the likelihood of particular events occurring to these groups. Groups share common behaviors, attitudes, and values as the result of a shared culture, though defining culture has proved problematic given the differing status memberships of each individual.

The study of inequality relies heavily on the analysis of data to adjudicate competing claims, and this chapter explains many of the most common methods used to design, conduct, and evaluate social science research. These skills will allow you to more effectively read subsequent chapters in this book and related published research. These techniques will also allow you to be a more competent consumer of data appearing in the media. The first part of the chapter outlines the steps involved in research design, including how to ask effective questions and how to design a study to answer those questions. The second part introduces statistical methods for describing quantitative data and discusses using those methods to draw general conclusions and evaluate hypotheses. This part of the chapter covers sample selection and basic descriptive statistics such as central tendency, variation, and skew. This part of the chapter also addresses social inference, the process of making inferences from the data to larger groups or populations.

In Chapter 8, our experiences of the behavior of energy in nature were formalized into laws dealing with the conservation of energy, the natural direction of processes, and the absolute zero of temperature. These laws were used to relate important thermodynamic functions to easily measured properties. The thermodynamic functions, in turn, were used to determine the direction of reactions and the conditions necessary for equilibrium.

In a nonlinear process of multiphoton absorption, the multiple photons are simultaneously absorbed. These photons can have either the same photon energy or different energies. This chapter begins with a general discussion of multiphoton absorption. The simplest of multiphoton absorption is two-photon absorption. It is a third-order nonparametric nonlinear optical process, in which two photons of the same or different photon energies are simultaneously absorbed. By comparison, three photons of the same or different photon energies are simultaneously absorbed in three-photon absorption, which is a fifth-order nonparametric nonlinear optical process. The detailed characteristics of the typical scenarios of two-photon absorption and three-photon absorption are discussed in this chapter.

Thus far we have described in general terms fundamental topics in metamorphism, including mineral reactions, metamorphic grade, and deformation textures. Now we turn to a more in-depth discussion of metamorphic reactions and mineral assemblages.

Practical electro-optic modulators are based on the Pockels effect. The electro-optic effects are generally discussed in the first section, and the Pockels effect is specifically addressed in the second section. The operational principles and characteristics of basic electro-optic modulators, including phase modulators, polarization modulators, and amplitude modulators, are discussed in the third section. In the fourth section, the structures, principles, characteristics, and advantages of guided-wave electro-optic modulators are discussed and shown through the forms of some well-established device structures, including Mach–Zehnder waveguide interferometers, directional coupler switches, polarization-mode converters, and traveling-wave modulators.

We raised important questions and talked about some patterns and trends in inequality in Chapter 1, but we offered little by way of explanation for those patterns. The objective of this chapter is to examine the major theoretical traditions in the study of inequality and to begin to apply these ideas to understand contemporary inequality.

Many techniques have been developed for the generation of laser pulses over a wide range of pulsewidths from the order of milliseconds to femtoseconds. The generation of a laser pulse is inherently a nonlinear optical process because all of the techniques utilize some form of optical nonlinearity that is coupled to the dynamics of a laser. In this chapter, the basic concepts of the primary techniques for the generation of laser pulses are covered, including gain switching, active and passive Q switching, active and passive mode locking, and synchronous pumping.