1.6.2 Metamorphic recrystallisation To consider metamorphic recrystallisation at its simplest, let's begin by imagining a sedimentary rock composed entirely of quartz grains – a quartz sandstone. Sandstone is a sedimentary rock and so has a fragmental texture (see Figure 7b). When it is subjected to high temperature and high pressure n
1.4 The formation of igneous rocks Igneous rocks are defined as having solidified from a molten state, either inside the Earth or on the surface at volcanoes.
References
4.7 Ageing brains: hope for the future Due to the enormous progress in the field of molecular and cell biology, new avenues in brain research have opened up.
3.1.2. After reading this article: The chapter by Teesson et al. (2002) will have presented you with a clearly written initial orientation to addiction. The article introduced addiction at several different levels of explanation in what the authors term a ‘biopsy chosocial model’ (p. 47). Such an integrated model is at the heart of the app
2.2 Specific issues in addiction The term ‘addiction’ carries a number of different meanings. The word is generally used with reference to drugs (e.g. heroin, nicotine, alcohol), where a person is described as being ‘dependent on’ or ‘addicted to’ a substance. Also, substances are described as ‘addictive’ or ‘non-addictive’, implying that addiction is an intrinsic property of the substance. Some people are addicted to food. Given that food is necessary, in what sense is
2.4 Other spectrographs Although the simple, single-slit spectrograph described above is the type you are most likely to find on a small telescope, there are other more complex designs available. Each of these has its own role to play in astronomical observations. An echelle spectrograph has a second dispersing element, either a second grating or a prism, which disperses the light at right angles to the direction of dispersion produced by the main grating. Without going into details, the effect is to pr
1.4.5 Summary of Section 1.4 Deciduous trees avoid the problems of winter by shedding their leaves. Plants can store nutrients over winter in a variety of structures. Amphibians have evolved behavioural responses (e.g. burying themselves) and physiological responses (e.g. different types of antifreeze in the body fluids) to winter. Hibernation occurs only in certain small mammal species and one species of bird and is accompanied by marked phy
1.2.1 The molecular level It is common knowledge that the freezing point of pure water is 0°C. Often, however, the temperature of water can fall below 0°C without it freezing, for two reasons: Any solvent containing a dissolved substance has a lower freezing point than when pure, which is why the sea freezes at a lower temperature than clean freshwater. The occurrence of supercooling, the phenomenon by which a fluid remains liquid at a temperature below
Learning outcomes After studying this unit you be able to: discuss the sequence of the events that are believed to have taken place in the history of the Universe, particularly the particle reactions that occurred in the first few minutes after the Big Bang, and the role of unified theories in explaining those events; manipulate large and small numbers in scientific notation, and calculate values for quantities when given appropriate numerical information.
Introduction From the moment that Galileo dropped two cannonballs of different sizes and weights from the top of the Leaning Tower of Pisa mankind has been fascinated by the impact of gravity. This unit looks at gravity, its impact on objects and how the energy involved in the movement of objects is dispersed or stored. This unit is from our archive and is an adapted extract from How the universe works (S197) which is no longer taught by The Open University. If you want to study formally with us, yo
4.2 Earthquake magnitude The magnitude of an earthquake is a measure of the amount of seismic energy released by it, so it is a quantitative scale. The scale of earthquake magnitude is called the Richter scale. Its development is described in Box 4, Charles Richter and the Richter earthquake magnitude scale. The Richter magnitude
4.1 Earthquake intensity Why are some earthquakes more destructive than others? There are three main reasons: location (an earthquake with a focus under an ocean at a large distance from land, for example, is not usually destructive, unless it generates a tsunami), depth (shallower earthquakes can be more devastating), but, most importantly, the size of the earthquake. A straightforward way to measure the size of an earthquake is to look at the damage it caused. This is a measure of the strength of the g
3 Where do earthquakes occur? How deep in the Earth do earthquakes occur? Most earthquake foci are within a few tens of kilometres of the surface. Earthquakes less than 70 km deep are classified as shallow-focus. Earthquakes with foci 70–300 km deep are classified as intermediate-focus and those below 300 km are deep-focus (Figure 7). Shallow-focus
Learning outcomes After studying this unit you should be able to: Explain the reasons for earthquakes Understand where in the world earthquakes are most likely to occur Describe the potential consequences of an earthquake Differentiate between earthquake intensity and earthquake magnitude Appreciate the enormous energies released by earthquakes
Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under Creative Commons licence. Grateful acknowledgement is made to the following sources for permission to reproduce material: Figure 1 English Heritage Photo Library; Figure 3 Endler, J. A. 1980, ‘Natural selection on
1 Charles Darwin Charles Darwin (1809–1882) briefly studied medicine in Edinburgh before going to Cambridge intending to become an Anglican clergyman. Soon after the voyage of the Beagle (1831–1836), during which he was gentleman companion to Captain FitzRoy, Darwin became convinced that biological evolution had occurred and saw how it could have been brought about by natural selection. Despite having gathered massive amounts of supporting evidence, Darwin refrained from publishing his revol
1.4.7 T is for Timeliness The date when information was produced or published can be an important aspect of quality. This is not quite as simple as saying that 'good' information has to be up to date. Here is an example of a news item from an on-l 3.1.1 (A) Science and certainty Pupils should appreciate why much scientific knowledge, particularly that taught in school science, is well established and beyond reasonable doubt, and why other scientific knowledge is more open to legitimate doubt. It should also be explained that current scientific knowledge is the best that we have but may be subject to change in the future, given new evidence or new interpretation of old evidence. 9.2 Marking up a text Although you might not think of this as note-taking, marking the text as you read can be a very useful part of the note-taking process. You can do this by using a highlighter pen, by underlining key points or by making notes in the margin. However, try not to overdo it and only highlight important points.
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