5.3.3 Ring-tailed lemurs

LoM p. 239 describes the life and habits of the ring-tailed lemur, drawing attention to what are commonly called their ‘stink-fights’ – a further example of the importance of smell in lemur society. But here the habit is prevalent in a species that is active by day and can spend as much as 40 per cent of its waking time on the ground. In fact, these animals seem equally at home on the ground and in the trees. Over time, some populations in Madagascar have become more ground-based than o
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2.4 Sources of errors

The following is a list of common problems that can lead to medication errors. They fall into three broad categories according to where they occur in the sequence from a drug being prescribed to it being administered to a patient. As you can see, the same types of mistake can occur in each category. Those errors that involve maths are highlighted in italics:

Prescription errors

  • Wrong drug prescribed (contraindicated, or allergy, o
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2.2.2 Precision

Measuring the same sample should give the same result every time if the equipment is precise. In practice, the information displayed by a measuring device can depend on several factors (such as temperature and humidity) and can drift slightly over time. Nevertheless, during the time it takes to complete a measurement sequence, all measurements ought to remain within a specified, small margin of error, often marked on the equipment. We will see later on, in Author(s): The Open University

1.10 Subtraction of decimal numbers

Subtraction of numbers can be used to answer questions such as ‘what's the difference between two values?’ or ‘if something has decreased by a certain amount, what's its new value?’ Subtraction can also be thought of as undoing the process of addition. For instance, instead of saying ‘£10 take away £7.85 leaves how much?’ you could say, ‘what do I have to add to £7.85 to get back to £10?’

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1.8.1 Study Note 4

If you have difficulty with this section, you might find it helpful to investigate some of the Government schemes aimed at improving maths skills. More information about such schemes can be found at http://www.direct.gov.uk/en/EducationAndLearning/AdultLearning/ImprovingYourSkills/index.htm (accessed 5 March 2008).

Box 3: The basics
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1.6.3 Litres and kilograms

The two physical units of measurement that you will probably come across most often in your workplace concern volumes of liquids and weight measurements. It's important to get a feeling for what various factors of ten look like, so that you can spot when there seems to be a mistake in a value that you've calculated or have been given by someone else.

The litre is the main unit of measurement for liquid volumes (written as liter in America), but what does a litre of fluid look like? What
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1.6.1 Getting comfortable with factors of ten

Moving a decimal point by one place changes the value of the number by a factor of ten. For instance, to multiply a value by ten you can just move the decimal point one place to the right:

Notice that if the starting number doesn't have a decimal point shown we can place
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1.5 Rounding to decimal places

Sometimes the result of a calculation gives a number with lots of decimal places – far more than you need or could reliably measure. For instance, suppose a patient is required to receive 5 ml of medicine a day, evenly spaced in three injections. How much medicine should they be given in each dose?

To divide the 5 ml of medicine into three equal parts would mean measuring out 5 ÷ 3 = 1.6666 ml (where the 6s keep repeating, or recurring indefinitely). It's not realistic or feas
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1.4.1 Study Note 2

An important point to remember when writing down measurements from a scale is never to quote more decimal places than you can reliably read from the measuring device you are using.

Figure 4
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5.2 Precambrian and Lower Palaeozoic Basement

The Precambrian and Lower Palaeozoic Basement of the British Isles is a series of nine discrete, exotic terranes whose boundaries are fault systems that have undergone large but usually unknown amounts of lateral and vertical movement over time (Figure 11 and Author(s): The Open University

5.1 Introduction

Figure 9
Figure 9 Lithotectonic units of the British Isles

In previous sections, it was revealed that in the British Isles, the Phanerozoic er
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4.5 How wide were the oceans?

Once evidence has been found to prove the existence of an ancient ocean, is it possible to calculate its maximum width? Palaeomagnetic studies can give geologists an idea of the palaeolatitude (N–S) of the ocean but not its palaeolongtitude (E–W), so depending on its orientation, an indication of how wide it was may not be possible. However, an approximate indication of how wide the former oceans were can be obtained by examining the fossil faunal assemblages that are present (e.g.
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4.3.2 Stage 2: Embryonic ocean basin formation (southern Red Sea stage)

If extension and rifting progresses sufficiently, this will lead to the development of an embryonic ocean along the site of the earlier rift zone (see Figure 6b). Prior to true oceanic lithosphere being produced, basaltic magma will be repeatedly intruded into the continental lithosphere along fractures and shear
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4.3.1 Stage 1: Continental rifting (northern Red Sea stage)

There are two mechanisms for breaking up a continental plate, the simplest of which is to pull it apart under lithospheric extension, forcing the mantle to rise up to occupy the ‘space’ that otherwise would be left by the thinned overlying plate (Figure 6a). Continued extension of this already thinned plate wi
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4.3 Continental extension

Understanding how and why continental plates break apart is extremely important, as this step precedes the formation and development of all new ocean basins. A generalised model for the extension, rifting and separation of continental plates has been developed by examining currently active rifting environments, such as the East African and Red Sea rifts, and comparing these with mature basins, such as the Atlantic Ocean. The East African and Red Sea rifts are regarded as representing continen
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4.2 Revealing past plate tectonic events

In Section 3 we referred to the Caledonian and Variscan Orogenic Belts. These are interpreted as representing past destructive plate margins or more strictly speaking, representing the final phases of ocean closure that resulted in continental collision. Section 4 explores the extent to which it is possible to detect different
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4.1 Introduction

In the theory of plate tectonics there are three main types of plate boundary, namely: constructive, destructive and conservative plate boundaries.

Figure 5
Figure
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3 A global view of Earth history

Figure 3, below, shows how the Earth's continents have drifted across the globe over the past 550 million years. This is a reconstruction of continental configurations of the Earth's landmasses during the Phanerozoic Eon. Note how northern and southern parts of the British Isles (red) were dispersed over two continents/tectonic plates until the end of the Devonian (a–d), and that all the landmasses formed one supercontinent during the Permo-Triassic (f).


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Learning outcomes

By the end of this unit you should be able to:

  • summarise and identify descriptions of the principal features of the main lithotectonic units of the British Isles, namely the Precambrian Basement, the Caledonian Orogenic Belt, the Variscan Orogenic Belt, the Older Cover and the Younger Cover;

  • identify any of the main terranes making up the British Isles on the basis of a description of its age, main rock types, dominant structures, and plate tectonic setting.


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