We have looked at calculations involving diagnostic analysis, calculations of various quantities at a given moment in time based on other values at that time. In this chapter, we consider a case of prognostic modeling, where we examine how a quantity changes with time, given an equation that relates that quantity to time (mathematically, where 𝑦 = 𝑓(𝑡)). In a prognostic model, the quantity we are modeling at some future time is somehow dependent on values at the present time.

Behavior genetics addresses questions of fundamental importance to humanity. We seek to understand what makes us unique individuals, but also what we share with our families and with other species. We seek to explain why we tend to act in certain ways while others tend to act differently. We also strive to contribute to the development of treatments for behavioral problems. We ask these and many other questions with a limited set of tools in the human behavior genetic toolbox. Ethical and technological constraints on human behavior genetic research combined with the inherent complexity of pathways from genes to behavior mean that a firm grasp of causality may forever remain out of reach. Even in cases where causality can be known, moral and ethical constraints limit potential applications of human behavior genetic findings. Any such applications to human beings are fraught with concerns about human rights.

As mentioned in the Preface, we have saved this chapter on how to write programs (except for a brief look in Section 6.2.7) until now because we wanted to focus our teaching of how to program on “doing” rather than on “talking about doing.” So, our problems so far have been generally on the short side. As we move into longer and more complex programs, we are in a place to consider more detailed advice about how to write programs. In this chapter, we discuss three topics regarding how to write programs: the process of writing programs, the importance of testing, and the importance of style conventions.

The purpose of irrigation is to supply water to plants, and this supply of water is made possible through infiltration into the soil. The infiltrated water is extracted by plant roots. Thus, infiltration plays a fundamental role in the design, management, and operation of irrigation systems. The objective of this chapter is to briefly discuss elementary aspects of infiltration and methods for computing it.

Gregor Mendel provided the framework for understanding genetics by systematically observing phenotypes in the context of breeding experiments even though he did not understand the underlying molecular biology. His theoretical model used the abstract notion of “factors” that we have since come to call genes. Quantitative genetics extends Mendel’s theoretical model to include many genes with small effects, called polygenes, to investigate phenotypic resemblance for those with known familial relatedness. Quantitative genetics does not require knowledge of the underlying molecular processes. In this chapter, we begin to focus on the core molecular mechanisms involved in heredity. We describe the molecules of heredity, how they are passed from one generation to the next, and how they participate in a variety of biological systems and functions. By understanding genetics at the molecular level, we will be better prepared to understand the mechanisms by which familial resemblance is achieved.

The Preface and To the Student sections describe how and why we structured the book and resources the way we did and how to make the most out of them. In the present chapter, we set the stage for the study of programming as an endeavor and Python as a language. We also describe what software needs to be installed in order to make use of the rest of the book.

Mendel’s theoretical model provided a powerful framework for understanding inheritance. However, traits that do not fit neatly into categories, but instead vary along some dimension (e.g., height), present a challenge to the Mendelian genetic model. This chapter discusses how this conundrum was resolved and how the solution led to the establishment of the field of quantitative genetics. Most behavioral traits vary along a dimension, so this issue is particularly relevant to behavior genetics. Next, the chapter introduces the concept of variance partitioning and discusses approaches commonly used in behavior genetics to investigate the roles of genetic and environmental variation on individual differences in behavior. Finally, the chapter discusses what has been one of the most important, and sometimes misunderstood, statistics in behavior genetics: heritability.

Basin irrigation is a common method for surface irrigation, especially in developing countries. A basin is an agricultural field with zero to little slope and is diked from all sides. The usual method of water application is flooding. This chapter briefly discusses the basin method of irrigation and its design.

A furrow is a small channel that runs either along or across the slope of the field. A field has a system of furrows and hence a furrow irrigation system comprises ridges and furrows. The objective of this chapter is to discuss the basic aspects and design of furrow irrigation.