8 Summary

  • We are biologically predisposed to provide for our offspring and may try to ensure that this provision continues after our death. However, our interactions with other members of society are wide-ranging and many people leave legacies to benefit the wider community.

  • All species alter their environment to some extent because they do not live in isolation from one another. The study of the interactions between plants, animals and their environ
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7 Some philosophical issues

In this unit we have considered global issues that have implications for our health and the health of future generations. This places our own lives in a different context and also indicates the uncertainties that surround the future. Whilst some environmental changes have very direct health consequences, we should not forget the indirect benefits that accrue from a healthy planet. The principle that ‘we should hand on to the next generation an environment no less rich than the one we
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6 Population growth

Earlier it was stated that three factors check population growth. These are predation, disease and insufficient food supply. For much of our history, our ancestors’ numbers were indeed limited by wars, disease and famine. The world population remained relatively stable until around 300 years ago. Then at the beginning of the 19th century (100 years after population growth started its geometric increase), the demographer Thomas Malthus predicted that population growth would outstrip food pro
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5.5 Indoor pollutants

Before leaving air pollution you might reflect that many of us spend most of our time indoors where the air quality can differ from that outside the building.

Question 30

In what ways will the air be different inside a building?


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5.3 Global warming

Media attention has been such that it would be hard to have missed the fact that global warming is considered to be a ‘bad thing’. Why should this be so? What is so wrong with being a bit warmer? Anyway, is global warming really occurring and, if it is, what are the causal factors responsible for it?

Let us deal with this last question first. As we sit on a beach in summer, or in a sunny window seat in winter, we are aware of the Earth being warmed by the Sun. In fact the Earth is w
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5.1 Pollution and loss of biodiversity

Unfortunately, halting the disappearance of species cannot be achieved simply by measures such as putting fences around special habitats and asking people not to pick the flowers or disturb the breeding birds. Many species are vanishing because of pollution. You probably have a good understanding of the meaning of this term, but it is variously defined. The Open University has a course on environmental control and public health, in which pollution is defined as the introduction into th
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1 1 Why sustainable energy matters

One of the greatest challenges facing humanity during the twenty-first century must surely be that of giving everyone on the planet access to safe, clean and sustainable energy supplies.

Throughout history, the use of energy has been central to the functioning and development of human societies. But during the nineteenth and twentieth centuries, humanity learned how to harness the highly-concentrated forms of energy contained within fossil fuels. These provided the power that drove the
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6.4.4 Environmental limits

There are many different definitions of what sustainable development means; you were given one in Section 5.3, and how this should guide policy. The underpinning concepts are: equity for human development, and limits on the capacity of the environment. The idea of environmental limits on the ability of the Earth's biophysical systems to cope with and adapt to pressures from human activity, whether from demand for natural resources, the waste products of modern economies, or from habitat modif
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6.2 The hierarchy of human needs

A second approach is to look at the human needs and wants from a more theoretical perspective. One such model was developed in the 1950s and 1960s by Abraham Maslow. Although it exists in many variants it is generally known as Maslow's hierarchy of human needs. In the most common interpretations it places the fundamental material needs of survival, such as food, shelter and safety at the base of a triangle, rising through social needs of belonging in human society, to
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4.4 Discussion

In this second case study, I have described two different trends in energy use by cold appliances over the last few decades. On the one hand the efficiency with which appliances use electrical energy has improved but, in spite of this, their consumption of electricity has increased significantly in recent decades. Since 2000 consumption has started to decline, probably as a result of the introduction of minimum energy standards. The trend will only continue if we demand and use the most energ
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5.6.3 Conformation and crystallinity

If there are key connections between the chain configuration and crystallisation, you might also expect some more subtle effects from rotation about chain bonds. After all, polymer chains must be able to twist into the regular conformation demanded for crystal structures (Figure 57(a)). And what influence will rotation have on
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Stage 2: Analysis of the existing situation (where are we now?)

Having defined and agreed on the problem, it is necessary to decide on the system in which you consider it plays a part. In practice the two stages are closely linked and the analysis of the existing system nearly always means a redefinition or refinement of the problem or opportunity. Identifying and defining the problem and the system or systems that relate to it are critical for the success of subsequent analysis.


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Appendix 1 Terminology

After studying this unit you should be able to explain the meaning of the following terms:

all-optical network

angle-polished convex connector

bandwidth-distance product

chirp

combiner

connector

continuous wave operation

dense wavelength division multiplexing

direct modulation directional coupler dispersion

dispersion compensation dispersion-shifted fibre electro-optic material excess loss external modulation extinction ratio four-wa
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3.1 Introduction

I've an opera here you shan't escape – on miles and miles of recording tape.

Flanders, M. and Swann, D. (1977) ‘The Song of Reproduction’ from The Songs of Michael Flanders and Donald Swann, London, Elm Tree Books and St George's Press, p. 99

Sounds, pictures, measurement data, financial statistics, personal details, etc. can all be recorded and stored on magnetic media, i.e. m
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3.2 Summary

The number of cycles of oscillation per second, both for a vibrating source and a pressure wave, is known as the frequency, symbol f Frequency is specified in hertz (Hz) or kilohertz (kHz). One hertz is one cycle per second; one kilohertz is one thousand cycles per second. Frequency and period are directly related. Frequency is the reciprocal of period:

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5.3 Purposeful and purposive behaviour

It is possible, as observers, to ascribe a purpose to what we or others do, the actions we take. How particular actions, or activities are construed will differ from observer to observer because of their different perspectives, which arise from their traditions of understanding. For example, in Author(s): The Open University

4 Introduction

(Please refer to Reading 4: Learning to act: managing and systems practice, by Andy Lane) This unit teaches some aspects of systems thinking and practice. But what does it mean to be a systems practitioner, and is it different to being a manager? This reading attempts to answer those questions.

First, I believe a good systems practitioner will be more competent at handling complex situations, more capable of managing their working and domestic lives, and more able to learn not only how
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3.6 Failure sequence

Following the discovery of the broken eye bar near the top of the northern suspension chain on the Ohio side of the bridge (Figure 36), it was possible to reconstruct the sequence of events during the collapse.

When the side chain separated, the entire structure was destabilised, simply b
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3.3.1 Sequence of events

It was important to establish the precise sequence of events leading up to and during the collapse. From which part had the collapse started? Why had so much of the structure been destroyed? Was there any prior warning of the failure? What part had the weather conditions at the time played?

Eyewitnesses were plentiful, and each had a different perspective of the bridge as it fell. There were some common parts to their statements. Most of the witnesses, especially survivors from vehicles
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7.1 Some basic principles of religious studies

Remember that in Section 4 I suggested that possible reasons for studying religion could be clustered together under two broad headings:

  1. to understand the society in which we live, the culture we inherit and the wider world of which we are a part;

  2. as part of a personal quest for religious
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