Introduction Motion is vital to life, and to science. In many ways it was the investigation of motion, initiated by Galileo Galilei in the late sixteenth century, and brought to a head by Isaac Newton in the seventeenth, that inaugurated the modern era of physics. Progress since that time has been so great that describing motion is now regarded as a fundamental part of science rather than one of its frontiers. Nonetheless, the description of motion played a central role in Einstein's formulation of the sp
6.3.2 Crystal Almost all modern gamma cameras use (thallium-doped) sodium iodide (NaI) as the scintillation crystal. A gamma photon interacts with the crystal to produce many photons of visible light. Sodium iodide is hygroscopic so cannot be left exposed to the air. The front surface is coated with a low atomic number metal that allows the gamma photons to pass through. The rear surface is covered with a transparent coating so that the visible photons can pass through to the photomultiplier tubes.
3 Computed tomography The aim of computed tomography (CT) is to produce an image of a slice of the body. (The Greek word ‘tomos’ means slice.) This is achieved by rotating a thin, fan-shaped beam of X-rays around the patient and measuring the intensity on the opposite side of the patient with a very large number of detectors. 2.3.1 The general view
Figure 16 shows a Voyager 2 image of a large region of Europa. Examine this image carefully, in order to answer Question 4. Introduction Until the 1980s, the icy satellites of the outer planets were scarcely thought of as places where life could ever have existed. Few could have imagined that one of them, Europa, would within twenty years have become the rival of Mars as a priority for astrobiological study. This unit recounts the history of our changing perceptions of the icy satellites, examines the available evidence for their internal structures, and considers the niches offered for life to begin and to be sustained. In th 3.1 Diurnal living In three particular respects, anthropoids have evolved features that have given them a competitive edge over other animals, especially prosimian primates. They have a diurnal instead of a nocturnal pattern of activity, they form all year round male-female relationships and live in social groups (which evolved differently and independently in lemurs), and they communicate extensively through gestures and vocalisation. A diurnal pattern of activity means that, like us, nearly all anthropo 7 Conclusions Throughout this unit, numerous examples of science promotion have been given, from the individual level of Pro-Ams to the supranational level of the EU Action Plan. Is there an appropriate political level for initiating science promotion or might a multi-level approach be more fruitful? Certainly there is evidence that local or sub-national initiatives can engage people – from Science Cafés and Cities of Science, to the Pub Understanding of Science beer mats with scientific questions 4.2 Experimental domestication of foxes In 1959, the Russian geneticist Dmitri K. Belyaev (1917–1985) launched a long-term experiment to tame captive-bred red foxes by selecting for a single behavioural trait: lack of fear and aggression towards humans. Over 40 years, more than 45 000 foxes were bred in captivity at a remote farm near Novosibirsk, Siberia. Various behavioural, physiological and morphological characters were studied in each fox. Selection for tameness was strict: each animal was assessed once a month for seven mon 1.4 The invisible Sun
Figure 7 shows an image of the Sun, taken when a huge prominence was visible (bottom left). The image was recorded using instruments that are sensitive to ultraviolet radiation rather than visible light, so the colours that you see are ‘false’. They simply indicate different levels of intensity of ultraviolet radiation. The u 2.4 Fruit bats and flying foxes In this section and the next, you will be asked to write answers to activities in particular numbers of words – Activity 3 asks for about 200 words and Activity 5 requires 150 words. Guidance of this type gives a useful indication of the degree of detail required in your answer. It is important that you conti 6 The good family Procyonidae As DA comments, this family is such an odd and varied collection that it doesn't have a common name [p. 170]. Its most familiar member (after which the family is named) is the raccoon, but the 19 species that comprise the family include mammals as diverse in habits and feeding preferences as the raccoon dog, the kinkajou and the red panda. There is considerable taxonomic controversy about the members of the raccoon family – including the status of the red panda. With the kinkajou, ear 4.2 Other members of the bear family Other omnivorous species of bear include the Asian black bear, the North American black bear and the Andean spectacled bear. Although polar bears spend their winters hunting seals out on the Arctic sea-ice, they have to come ashore when the ice melts in spring and find other sources of food. 2.3 Food chains and food webs This section includes two graphs. Figure 2 has the standard numerical values on its axes, in this case years from 1830 to 1930 on the hor Acknowledgements The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: The content acknowledged be 5.2 Differences between the sexes In biology, ‘sex’ refers to a particular form of reproduction, sexual reproduction, that is distinct from asexual reproduction. As you know, sexual reproduction involves the production of eggs by females and sperm by males; eggs (or ova) and sperm are known as gametes. It is a universal feature of mammalian biology that in sexual reproduction there are two types of gametes and that progeny are produced by the fusion of two unlike gametes to form a single cell called the zygote. The zygote 6.2.3 Measurement of the angular distribution of the 3 K radiation How are such angular distributions to be measured? One way, of course, is to take a radio telescope and swing it round the sky, taking readings in different directions. But as is clear from Figure 20(a), the atmosphere itself emits microwaves. There is therefore a grave danger, with this method, of picking up different contri 5.1.3 Getting agreement with Faraday's law Substituting Equation 7.21 into Faraday's law gives This shows that a propagating electric wave is automatically accompanied by a transverse magnetic wave. The magnetic field oscillates in the y-direction, which is perpendicular to the direction of propagation and 4.3 Mercury Mercury is a naturally occurring metal which, in its pure form, is not particularly toxic. Under normal conditions of temperature and pressure, it is a silvery-white liquid which readily transforms into a vapour. When vaporised, it enters the atmosphere, remains there for a long time, and is circulated globally (WHO, 2005b). Through chemical reaction and precipitation it enters freshwater lakes and rivers, where it accumulates in the sediments at the bottom. Here it is transformed by bacteria 3.2 The anatomy of a graph A graph shows how two different types of data that can take on different values (known as variables) are related, or change in relation to each other; for instance, how a patient's temperature changes over time. Each measurement consists of two variable values: the patient's temperature and the time at which the temperature was taken. Author(s): 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
Activity 2
