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5.1.5 Getting agreement with the Ampère–Maxwell law

Finally, our electric and magnetic fields must satisfy the Ampère–Maxwell law in empty space. Using Equations 7.21 and 7.23, we obtain

which requires that

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4.5 Endocrine disruptors

Then he was a she…

(Lou Reed, American rock singer)

In 1996, a book called Our Stolen Future was published, bringing to public attention a debate that had been simmering among biologists for some time. Written by Theo Colborn and two colleagues at the World Wildlife Fund (WWF), this book presented the hypothesis that certain industrial chemicals, commonly found as environmental pol
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3.2 The impact of climate change on global freshwater resources

The availability of freshwater will be significantly altered in a future world affected by climate change (Houghton, 2004). In some regions, water availability will decrease; in others it will increase. Precise predictions about the extent and exact location of such changes cannot be made because they are based on climate models, the accuracy of which is uncertain. However, there is wide agreement that probable changes will include:

  • More rain in north
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Introduction

This unit examines why water shortages are predicted as a result of the world's growing population and the importance of access to clean and safe drinking water in public health. It looks at the distribution of water throughout the world and problems with contamination, topics of wide general interest.

Introducing health sciences: a case study approachI (SDK125)


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3.6.1 Radioactivity and bugs!

Many natural processes involve repeated doublings or halving at regular intervals. You may have come across this already in your work, in the context of bacterial growth or radioactivity. In this section, we are going to look in more detail at bacterial growth and radioactivity and we will be using graphs to examine how the numbers of bacteria or numbers of radioactive atoms change over time.


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3.2.2 Choice of scale

It's important to choose a scale that covers the range of values you have recorded for that particular axis. If the scale is too big, then all of your measurements will be bunched up at one end of the graph, making it difficult to read. It is also very important to keep the scale consistent all along the axis, i.e. don't suddenly change the spacing between the units of measurement on an axis.


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7 Unit questions

Now you have completed this unit, try the following questions to test your understanding of this material.

Question 19

6.3 Chemical formulas

By using symbols, elements can be represented much more conveniently and much more briefly. This method of using symbols can be extended to compounds. You will now look further into this idea using a very familiar compound: water. Recall which atoms there are in a water molecule.

Question 24

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2.6.1 (a) Using Lego as a model

In this kind of building set, there are a limited number of types of block and each block has a particular shape. Just as importantly, each one has a particular way in which it can link to other blocks because of the way the studs are arranged.

The blocks can help you see how the atoms link in a molecule of water. Look at Figure 7 where the red brick represents an oxygen atom and the white bricks represent hydrogen atoms. There are only two locations where the hydrogen atoms can join th
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2.6.2 End-of-unit questions

Question 8

Express the following numbers using scientific (powers of ten) notation:

  • (a) 2.1 million

  • (b) 36 000

  • (c) 1/10

  • (d) 0.00005


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5.3 GM Nation? The public debate

The key objective of the national dialogue on GM was to allow the exchange of views and information – members of the public would presumably learn more about the issues; experts and policy makers would learn more of the reasoning behind the public's concerns.

Question 16


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Introduction

This unit is an adapted extract from the course Science in context (S250)

In recent years, scientists have made huge gains in their understanding of how genes can be altered and transferred from one organism to another – but that knowledge has been acquired amidst controversy and concern. The deep ethical concerns that have resulted from the emergence of genetic manipulation are explor
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7 Conclusion

In this unit we have studied animals in the context of their own habitat rather than using the traditional comparative physiology approach of comparing organ systems in different species. Although we have looked at extreme habitats, specifically deserts, it has become clear that, for many species, extreme physiological adaptations are not present and that even endotherms, birds and mammals rely on behavioural strategies, thereby reducing the need for physiological strategies that are costly i
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6.2 The hypothalamus as central regulator

Research in the past 30–40 years has established that the hypothalamus, which lies below the thalamus and above the optic nerve chiasma and the pituitary gland in the brain, fulfils all of the functions listed above, at least in part. The main function of the hypothalamus is homeostasis. Factors such as blood pressure, body temperature, fluid and electrolyte balance, and body weight are held to constant values called the set-points. Although set-points can vary over time, from day to
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5.3 Metabolism

Molecules diffuse more slowly at low temperature: measurements of the rates of diffusion of small molecules such as lactic acid, Ca2+ and analogues of glucose and ATP through fish muscles produced Q10 values of 1.75–2.04 between 5 and 25° C. Nearly all enzyme reactions are slower at low temperatures (although sometimes whole pathways can be faster if an inhibitor is more inhibited by low temperature than are the catalysts). So, in the absence of temperature compensat
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5.2.1 Blood pigments

The solubility of oxygen (and of many other gases) in water increases with decreasing temperature: at 0° C, seawater holds 1.6 times as much oxygen when saturated as at 20° C. This fact, and continual disturbance by frequent storms, mean that the surface waters of polar oceans are very well oxygenated. A family of 17 species of nototheniid fish, the Channichthyidae, have no erythrocytes, no haemoglobin and almost no myoglobin at all stages of the life cycle (Section 1.5).

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4.3 Humans in polar regions

Humans evolved in tropical Africa and gradually colonized colder climates during the Pleistocene ice ages. There have been permanent populations in the Arctic for several thousand years, mostly Inuit (Eskimos) in what are now Canada, Alaska and Greenland, and several groups in northern Europe and Russia, such as the Saami (Lapp) in Scandinavia and the Chukchi in Siberia. Such people do not grow crops and keep only a few domestic animals, mostly for transport (e.g. husky dogs or reindeer), not
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3.5 The structure of adipose tissue

Since food is only available seasonally or intermittently at high latitudes, many arctic birds and mammals, including polar bears, Svalbard reindeer, arctic foxes, seals and walruses, naturally accumulate large stores of fat. The quantity of energy stored and the metabolic control of its use are finely adjusted to the habits and habitat of the species. This section is concerned with the cellular structure and anatomical organization of adipose tissue in such naturally obese species. Most labo
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