1. Tracking the AIDS Epidemic in the United States: Diffusion through Space and Time
© 2006 John Wiley & Sons, Inc. This presentation may be used and adapted for use in classes using the fourth edition of Human Geography in Action. It may not be re-distributed except to students enrolled in such classes and in such case must be password protected to limit access to students enrolled in such classes. Students may not re-distribute portions of the original presentation.
Chapter 3

2. Relocation Diffusion
The spread of an idea through physical movement of people from one place to another.
DISCUSSION:
* Restate this definition in your own words.

3. Relocation Diffusion DISCUSSION:
* Does the number of green individuals increase or remain the same?
* How is this diagram an over-simplification of the concept of relocation diffusion?
Relocation Diffusion

4. The Spread of Cricket Figure 3.1 (p. 63) DISCUSSION:
* What is the relationship between the two maps in this slide?
* How might it be that the U.S. is an Affiliate Members if the International Cricket Council?
[indirect connection to Commonwealth, immigration, large population base]
The Spread of Cricket
Figure 3.1 (p. 63)

5. Expansion Diffusion DISCUSSION:
* Does the number of green individuals increase or remain the same?
* How is this diagram an over-simplification of the concept of expansion diffusion?
Expansion Diffusion

6. Relocation Diffusion vs. Expansion Diffusion
DISCUSSION:
* What are examples of phenomena that are more likely to spread via relocation than expansion diffusion?
* What are examples of phenomena that are more likely to spread via expansion than relocation diffusion?
The key distinction between relocation and expansion diffusion is whether the number of adopters is expanding.

7. Percentage of Population That Adopts the Idea or Innovation
Majority
Adopters
Laggards
Innovators
Time
DISCUSSION:
* Why is the S-curve considered a temporal rather than a geographic issue?
* At what point in time on the S-curve does the number of adopters increase the fastest?
* Think about your personal life? Are you an innovator or a laggard in fashion? What about technology purchases?
S-Curve
Figure 3.2 (p. 64)

8. U.S. Cell Phone Subscribers
DISCUSSION:
* What percentage of the population subscribes to cell phone service? [calculate from total U.S. population of 300 million on p. 63]
* What percentage do you think this would be if only adults were considered?
Figure 3.3 (p. 64)

9. Hydrogen Fuel Stations Worldwide
DISCUSSION:
* What other phenomena might follow the S-curve adoption pattern?
Figure 3.4 (p. 65)

10. Contagious Effects Figure 3.5a (p.66) DISCUSSION:
* How is this diagram an over-simplification of the concept of contagious effects?
Contagious Effects
Figure 3.5a (p.66)

11. The Spread of Islam Figure 3.6 (p. 67) DISCUSSION:
* What irregularities do you notice in the contagious effect in this example? [i.e. Indonesia]
* Why do you think they exist? [trade routes]
The Spread of Islam
Figure 3.6 (p. 67)

12. Hierarchical Effects Figure 3.5b (p. 66) DISCUSSION:
* What are the large cities in your state or province which would first be impacted by a diffusion process spread by hierarchical effect?
Hierarchical Effects
Figure 3.5b (p. 66)

13. Hierarchical Effects Figure 3.5b (p. 66) DISCUSSION:
* Is the diffusion in this time frame only from large to medium cities?
Hierarchical Effects
Figure 3.5b (p. 66)

14. Hierarchical Effects Figure 3.5b (p. 66) DISCUSSION:
* Does hierarchical effect mean that someone in a small city is guaranteed to encounter the idea, innovation,
or disease only after it has spread first to medium cities?
Hierarchical Effects
Figure 3.5b (p. 66)

15. DISCUSSION:
* Which of the above-shown cities (not labeled) would be considered medium-sized
and therefore be included in the second wave of hierarchical effect?
Major U.S. Cities
Larger cities are generally the first to experience phenomena which spreads by hierarchical diffusion.
Online Activity

16. Contagious Effects Relocation Diffusion Hierarchical Effects
Expansion Diffusion
DISCUSSION:
* How does this slide represent the relationship between the type of diffusion and the effect?
* Does a phenomena usually spread exclusively just by one type of diffusion or effect?
Hierarchical Effects

17. A biased innovation a barrier to diffusion?or
a barrier to diffusion?
• ownership of BMW vehicles
• a joke in Quebec which doesn't translate into English
• the spread of certain ring tones
DISCUSSION:
* Which one of these bullet points are examples of a biased innovation vs. a barrier to diffusion?
* Could some of these be both (perhaps if worded differently)?
* How could some of these be "facilitators" instead of barriers to diffusion of a phenomena?
• the popularity of a new movie
• the popularity of a new movie in Spanish
• a software program subject to export restrictions
• a disease found only among the mammals on a large island

18. Other Examples of Diffusion
clothing fads
video games
radio broadcasting
punk rock
DISCUSSION:
* What other examples can you think of?
computers
chemical fertilizers for farming
anti-HIV drug cocktail

19. Name That Key Term

20. Physical, political, cultural, or economic impediments to diffusion.
The spread of some phenomenon over space and through time from a limited number of origins.
Spatial Diffusion
Innovations (or diseases) that are less (or more) accessible to people of a certain gender, class, age, or ethnicity. This diffusion theory emphasizes social context in addition to spatial context.
Biased Innovation
Physical, political, cultural, or economic impediments to diffusion.
Barriers to Diffusion
A process in which items being diffused leave the originating areas as they move to new areas (i.e. the items diffuse with people migrating).
Relocation Diffusion

21. Expansion Diffusion Urban Hierarchy
A process in which the items being diffused remain and often intensify in the origin area as new areas are being affected (i.e. the items diffuse from person to person).
Expansion Diffusion
A system of cities consisting of various levels, with few cities at the top level and increasingly more settlements on each lower level. The position of a city within the hierarchy is determined by the types of central place functions it provides.
Urban Hierarchy

22. Hierarchical Effects Contagious Effects
Diffusion of a disease, cultural trait, idea, or innovation from larger to smaller places, leaping over nearby but small places in the early stages. This diffusion emphasizes the size distribution of urban places (i.e. the urban hierarchy) in explaining the spread of things over time and space.
Hierarchical Effects
Diffusion of a disease, cultural trait, idea, or innovation that spreads outward from a node or epicenter in wave-like fashion. This diffusion emphasizes the frictional force of distance in explaining the spread of things in time and space.
Contagious Effects

23. Tracking the AIDS Epidemic in the United States: Diffusion through Space and Time
Case Study
Chapter 3

24. After completing this chapter, you will be able to:
• Define and give examples of hierarchical diffusion.
• Define and give examples of contagious diffusion.
• Interpret a scatter diagram.
• Interpret animated maps that change over time.
• Calculate cumulative totals and make
a cumulative graph.
• Describe the diffusion of AIDS in the United States.

25. Background on AIDS • What is AIDS? • AIDS in Africa
• Global pathways and global hotspots
• Current situation in the United States

26. Population Pyramid for Botswana
Figure 3.8 (p. 71)

27. Probable Early Diffusion of AIDS
Figure 3.10 (p. 72)

28. World HIV/AIDS Rate for Adults
Figure 3.11 (p. 73)

29. Activity 1: Mapping the Diffusion of AIDS
Online Activity

30. Activity 2: Distance from Initial Centers
Typical Downward-Sloping Scatterplot
Figure 3.13 (p. 80)

31. Online Activity

32. Activity 3: S-Curves
Online Activity