Irrigated agriculture is vital for food security. Irrigation systems that make it possible are usually designed with the long-term objective that they are economically sustainable, although that is not always the case in many developing countries. This chapter visits fundamental concepts needed for analyzing benefits and costs, which in the long term define the benefit–cost ratio.

In thewe saw how we can use Python as a basic calculator. Along the way, we were introduced to expressions, variables, and environments to type in and run Python code. In this chapter, we will extend our use of Python as a basic calculator to tasks associated with a scientific calculator.

Behavior genetics – the scientific study of heredity–behavior relations – has come of age. Since the middle of the twentieth century, accumulating scientific evidence has shown that genetic differences between individuals play a significant role in behavioral differences between them. In fact, it is now generally accepted that genetic variation is an important contributor to individual differences in behavior. Although the fundamental question about the role of inheritance in behavioral resemblance is not new, recent technological advances provide new ways to peek behind nature’s curtain. It is easy to get excited about the potential for discoveries in behavior genetics. We appear to be entering a new era in which it may be possible to understand the biological mechanisms responsible for familial behavioral resemblance. However, we should enter this era with humility. The history of behavior genetics is full of periods of excitement followed by disappointment. It also contains sobering lessons of scientific hubris and state-sponsored human rights violations. There is a lot to be excited about, but it is important to remember history, and to understand the limitations of behavior genetics, especially when considering the application of behavior genetic findings to human beings.

When an agricultural field is irrigated, the common thought is that it should be irrigated efficiently so that crop yield is maximized. Does it mean that irrigation efficiency should be maximized? Is maximum efficiency desirable under all circumstances? How does irrigation efficiency relate to the type and design of the irrigation system? Should irrigation efficiency be entirely based on the amount of water consumed by plants? Before addressing these and related questions, we must first address the question: What is meant by efficient irrigation or irrigation efficiency? This chapter discusses the concept of irrigation efficiency and related aspects.

Compared with their predecessors, modern computers are fast. Even wearable computing devices today boast processing power that only a few human generations ago would have placed them in the pantheon of the fastest computers on the planet. No amount of computational power, however, will do us any good if the program we write makes poor use of processor cycles and memory. Throughout the present work, we have focused on trying to “get the job done” and have written our programs with a focus on accomplishing the science or engineering task at hand rather than the speed at which the program accomplishes the task.

For evolution by natural selection to work, hereditary material must vary between individuals and such variation must cause individual differences in traits that are directly, or indirectly, involved with reproductive fitness. In other words, genetic differences between individuals are the raw material of evolution, but only if those differences produce differences in traits that are subject to natural selection. Theodosius Dobzhansky’s assertion that biology only makes sense in the context of evolution makes it clear that genetic variation is a cornerstone of the entire field of biology. It is certainly the basis of behavior genetics, where we strive to understand the role of genetic differences in producing individual differences in behavior.

In previous chapters, we have used looping and array syntax to analyze data in arrays of a number of dimensions. When we used looping constructs to examine the elements of arrays, we also found that branching statements like the if statement enable us to do different calculations depending upon whether certain conditions are true or not. Is it possible, however, to include branching logic into array syntax and avoid writing loops while still doing different calculations depending on whether certain conditions are true or not? In this chapter, we examine array functions and constructs that enable us to do exactly that.

Groundwater is of vital importance for agricultural irrigation. In almost all countries, a significant portion of irrigation water is derived from groundwater using wells. In developing countries where farm holdings are small, one well may suffice but a number of wells are used in large farms. This chapter discusses rudimentary aspects of groundwater and wells from the perspective of irrigation. Although the material covered in the chapter is based on gross simplifications, it has been found to be useful nonetheless for irrigation purposes.

Take a moment to think about cells. Which type of cell is your favorite? If you were to ask biologists, you would likely get a wide variety of responses. Some might have a soft spot in their hearts for red blood cells, or liver cells, or maybe even single-celled organisms like bacteria. However, if you were to ask psychologists which cells they prefer, you would likely learn that most of them favor neurons. Because it is with neural mechanisms that animals access, process, and act on information. Neural activity underlies all behavior, and therefore neurons occupy a privileged position in psychology.

Channels are a vital part of irrigation systems. They are the link between the source of water and the irrigation field. Channels used in irrigation systems can be either erodible or non-erodible, or earthen or lined. Flow in channels is governed by the principles of hydraulics. This chapter discusses rudimentary aspects of hydraulics and the design of open channels.