1.1 The Sun at visible wavelengths The Sun is seen as a blindingly bright, yellow object in the sky. The part of the Sun that you normally see is called the photosphere (meaning 'sphere of light'); this is best thought of as the 'surface' of the Sun, although it is very different from the surface of a planet such as Earth. Its diameter is about 1.4 million kilometres, making the Sun's volume roughly one million times that of the Earth. The photosphere is not solid. Rather, it is a thin layer of hot gaseous material, abo
1 Introducing cosmology General relativity has a very different conceptual basis from that of Newtonian mechanics. Its success in accounting for the precession of Mercury's orbit, and the bending of light by massive objects like the Sun, gives us confidence that our picture of space and time should be Einstein's rather than Newton's. In this and the following courses, we turn our attention to the study of the large-scale structure of spacetime. We see how spacetime as a whole is curved by the gross distribution of m
Keep on learning   There are more than 800 courses on OpenLearn for you to 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 palaeolongitude (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. 4.1 Introduction In the theory of plate tectonics there are three main types of plate boundary, namely: constructive, destructive and conservative plate boundaries. 3.5 Electrophysiological studies of language processing Brain imaging and aphasic studies helped us localise the subparts of language processing within the brain. However, they have shed little light on how processing unfolds in real time. This is because contemporary brain imaging is quite poor at showing changes in activity through time in fine detail, so it is hard to pick up something that may be happening slightly before something else. In Author(s): 12.8 More revision questions (a) If two tones are broadcast through headphones at an intensity of 100 dB SPL, which will sound louder, a 100 Hz tone or a 1000 Hz tone? Why? (b) How lo 12.1 Localisation of sound in the horizontal plane While information about frequency and intensity is essential for interpreting sounds in our environment, sound localisation can be of critical importance for survival. For example, if you carelessly cross the street, your localisation of a car's horn may be all that saves you. Our current understanding of the mechanisms underlying sound localisation suggests that we use different techniques for locating sources in the horizontal plane and vertical plane. 7.2.2 The ‘where’ pathway The ‘where’ pathway involves the ventral cochlear nuclei, the superior olivary complex and the inferior colliculus. The superior olivary complex is composed of the lateral superior olive (LSO) and the medial superior olive (MSO). The neurons in the superior olivary complex are the first brainstem neurons to receive strong inputs from both cochleae and are involved in sound localisation. The MSO receives excitatory inputs from the cochlear nuclei on both sides and is tonotopica 3.5.1 Hair cells transform mechanical energy into neural signals The tectorial membrane runs parallel to the basilar membrane, so when the basilar membrane vibrates up and down in response to motion at the stapes, so does the tectorial membrane. However, as shown in Figure 14, the displacement of the membranes causes them to pivot about different hinging points and this creates a shearing force bet 3.4 The organ of Corti and hair cells We have established that the vibration patterns of the basilar membrane carry information about frequency, amplitude and time. The next step is to examine how this information is converted or coded into neural signals in the auditory nervous system. To do so, we must look at the organ of Corti in some detail since it is here that the auditory receptor cells that convert mechanical energy into a change in membrane polarisation are located. 5.2.1 The GM Science Review The review was undertaken by the GM Science Review Panel, chaired by the Government's Chief Scientific Adviser, Sir David King. Its role was to assess the evidence available in the peer-reviewed scientific literature. The panel produced two reports, the first in July 2003 and the second in January 2004. The main conclusions of these reports are listed below. The risk to human health is very low. There is little likelihood of such plan 3.2.1 Formal publication The first formal, peer-reviewed, publication of part of Pusztai's work came in the Lancet in October 1999. Pusztai and his co-author Stanley Ewen had developed the work to include measurements on the effect of GNA potatoes on the structure of the rat intestine. They were looking for any effect of the GM diet on the mucosal cell layer lining the gut. Any increase in thickness would indicate that the diet had prompted increased growth of these layers, seen as a deleterious effect. In the Social issues and GM crops 2.12 Fluid balance Although a person can survive for several weeks without food, without fluids, someone can survive for only a few days. A loss of water equivalent to just 1% of body weight is enough to make someone feel thirsty and to have an effect on ability to concentrate. Such a loss has been shown in some studies in schools to result in a 10% decrease in the mental performance of children. A 4% loss results in dizziness and reduced muscle power. By the time there is a 6% loss, the heart is racing and swe 2.4.2 Magnesium (Mg) Magnesium is also present in bone in the body and in the soft tissues, although in much lower quantities than calcium. It is important in the activity of more than 300 enzyme systems, in particular those using ATP. It is involved in the synthesis of proteins and in many other reactions in the body. In plants, magnesium is part of the chlorophyll molecule, so it is present in green vegetables and is found widely elsewhere in the diet, so intake is normally adequate. In some areas, there are lo Learning outcomes After studying this course, you should be able to: understand something of the role of a genetic counsellor and its non-directiveness understand the difference between pre-natal diagnosis, childhood testing and adult testing and give some examples of diseases that may be tested for understand the ethical and moral difficulties involved in making decisions on whether or not to carry out such tests. 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 ident 1.9 Summary and conclusion: ‘take-away messages’ It helps to understand the PhD in context: the modern PhD is typically a three-year research training providing evidence of the ability to conduct and bring to fruition an independent programme of research. It requires rigour and an ability to enter the discourse, but its scope is limited and it does not require perfection. Models of study and models of dissertations vary for different universities, disciplines, and topics. The key is to understand what is appropriate for your particular prog 2.1 Why study ecology? These days, bird watching is a popular leisure activity and in the past so were collecting insects, wild flowers and birds’ eggs (although such activities are not now recommended – indeed, they are often illegal – because of the potential damage they cause to flora and fauna). Some amateurs are or were truly experts in their fields. In fact, much of the original identification of the British flora and fauna was done by amateur naturalists. Many a Victorian vicar or other self-taught nat
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The genetic manipulation of plants and animals and their use in agriculture is one of the most controversial scientific developments of recent times. This free course, Social issues and GM crops, takes a look at the science behind the headlines and the complex interactions between scientific and social factors. By the end of the course it's hoped that you will have a clearer idea not only of what is possible with GM but what may be considered desirable.
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