2.2 Persistent currents lead to constant magnetic flux An important consequence of the persistent currents that flow in materials with zero resistance is that the magnetic flux that passes through a continuous loop of such a material remains constant. To see how this comes about, consider a ring of metal, enclosing a fixed area A, as shown in Figure 6a. An initial magnetic field B0 is applied perpendicular to the plane of the ring when the temperature is above the critical temperature of the material from which the rin
References Optional reading Debates about the relationship between science, citizenship and democracy continue to influence public policies related to science communication and public engagement in science. In part, these debates involve discussions about scientific and other ways of knowing. For an introduction to these issues, see Irwin (1999). This premise, of exchanging information and learning from others, is also relevant to your communication with other expert scientists. As a research student you will lear Optional reading It is worth noting that the structure of scientific papers has developed towards the structure that Medawar outlines. In this respect, the original works of Galileo or Newton would look very different from a contemporary journal article. If you are interested in considering these issues further, the work of Montgomery (1999) should be useful. For a more detailed discussion of the processes and motives of communicating science within the scientific community, see Rowland (1999b, 1999c).< Optional reading If you are interested in considering the role of the internet on science communication practices, you may find the following references are of interest: Wulf (1999), Rzepa (1999) and Rowland (1999a). So far, you have been asked to reflect on your experiences of science communication both as a receiver and as a producer. You have also considered a definition for communication in terms of different types of media, noting how this influences the context for science communication (e.g. ‘f 2.9 End of section exercise After reading Section 2 you could conduct the following exercises as part of your evidence of achievement. You may like to discuss this activity with your supervisor. Write a reflective account of some of the skills you identify as important a 1.5 Key dissertation ingredients A number of ingredients are essential for a satisfactory dissertation: a thesis, i.e. one coherent overriding ‘story’ or argument situation in existing knowledge, i.e. a critical review of prior research which motivates and justifies the research question contribution of something new appropriate voice and argument, i.e. the provision of clear and explicit evidence, substantiation, and chain of in 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 1.6.1 Causes of metamorphism What natural process could cause a rock to be heated? Heating can be caused when hot magma is intruded into a cool rock. On the o 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. 1.3.2 Rocks Any naturally formed solid assemblage of mineral grains can be described as a rock. The mineral grains may be fragments of crystals or intact crystals and their size can range from a few micrometres (1 micrometre = 10−6m) to a few centimetres. A rock may consist of one type of mineral but more usually it consists of several minerals. Rocks can be classified according to the way in which the grains are arranged, although the identity of the minerals present (for example, the rock References 8 Websites for further information: Primers on drug addiction: For general in 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. 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 2.1.2 Diffraction and interference of light When light, or indeed any type of wave, passes through a narrow aperture, it will spread out on the other side. This is the phenomenon of diffraction. For example Figure 17 shows the diffraction of water waves in a device called a ripple tank. The extent to which waves are diffracted depends on the size of the aperture rel 1.5.1 Light-gathering power One of the key benefits of using a telescope is that it enables fainter objects to be detected than with the naked eye alone. The light-gathering power of a simple telescope used with an eyepiece is defined as where Do is the diameter of the objec 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 Introduction In this unit, we study one aspect of the fluctuating nature of an organism's environment. We consider how organisms living in a temperate climate, such as that in Britain, are adapted to cope with winter. You will see that there is much diversity of adaptations among organisms, with different species coping with the demands of a fluctuating environment in quite different ways. As cyclic variations are a widespread feature of environments, the range of adaptations to them is an important sourc 1.7 The hadron era Time: 10−5 s to 100 s Temperature: 3 × 1012 K to 109 K Energy: 1 GeV to 300 keV From the time that the temperature fell to about 3 × 1012 K, at about 10−5 s after the Big Bang, stable baryons (protons and neutrons) began to form from the up and down quarks that remained after the annihilation of matter and antimatter.
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