1.1 Introducing the decimal system of numbers Many different systems for writing numbers have been developed over the history of humankind. The easiest way of counting small numbers is to use your fingers, and for this reason many numerical systems, such as the decimal system, are based around the number ten. But what happens when you run out of fingers to count on? Numbering systems get round this problem by using a system of scale in which many small units are represented by a single larger unit, and many of these la
5.6 Younger Cover The Younger Cover can be found covering a large part of England, and to a lesser extent, north-east Ireland, south-west Scotland, Arran, Mull, and the north of Skye. From the Ten Mile Maps and Author(s):
5.5 Variscan Orogenic Belt Unlike the Caledonian Orogenic Belt, outcrops of the Variscan Orogenic Belt are limited to the south-west of England, southern Wales and the south of Ireland (see Figure 9 and Author(s):
12.7 Summary of Section 12 For precise localisation of a sound source, binaural cues are required. Two types of binaural cue are used to localise non-continuous sounds in the horizontal plane: interaural time differences, which are most efficient for low-frequency sounds (20–1500 Hz) and interaural intensity cues, which are important for high-frequency sounds (1500–20 000 Hz). The frequency responses in the superior olive reflect these differences. The medial superior olive includes neurons that are responsiv
3.8 Revision questions Discuss the two ways in which the middle ear increases the effectiveness with which sound is transmitted from the external ear to the inner ear. 3.5.3 Mechano-electrical transduction is rapid Many other sensory receptors, such as photoreceptors and olfactory neurons, employ second messengers in the transduction process. This is not true for hair cells. The rapidity with which they respond makes this impossible. In order to deal with the frequencies of biologically relevant stimuli, transduction must be rapid. The highest frequency humans can hear is about 20Â 000 Hz. This in effect means that hair cells must be able to turn current on and off 20Â 000 times per second (200Â 000 tim 3.5 Neural transduction The critical event for the transduction of sound into a neural signal is the bending of the stereocilia of the hair cells. In this section we will examine how the flexing of the basilar membrane leads to the bending of the stereocilia and the production of a neural signal. Richard Feynman Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: Introduction This unit is an adapted extract from the course Science in context
(S250) In recent years, scientists have made huge gains in their understanding of how genes can be altered and transferred from one organism to another – but that knowledge has been acquired amidst controversy and concern. The deep ethical concerns that have resulted from the emergence of genetic manipulation are explor 2.2 Interstellar space is not empty The difference between the apparent brightness of a star (as measured by its apparent magnitude), and its luminosity (represented by its absolute magnitude) is defined by the distance of the star. We can explicitly state this relationship as in Equations B and C: References 5.2 Sexually dimorphic nucleus of the preoptic area (SDN-POA) As well as affecting behaviour (Section 3.4) neonatal testosterone also affects the physical characteristics of some areas of the brain. One of these is a small area of the hypothalamus, the medial preoptic area, which, although small, is much larger in males than in females. This size difference is mediated by testosterone. 4.4 Summary of Section 4 Two important points emerge from this section. The first is the powerful effect of maternal contact on the development and later behaviour of their charges. In the Feldman study the disadvantages of prematurity were essentially overcome by early maternal contact. The second point is that some behavioural traits really do run in families, without being genetic. The Francis study clearly showed that some aspects of Open Field behaviour were the result of nursing care. 4.1 Introduction to minerals and why we need them Both vitamins and minerals are essential in the diet in small quantities and so they are often grouped together as micronutrients. Which items in the diet are classified as macronutrients? Introduction Genes are units of inheritance that contribute to a person’s behaviour and health. In this unit you will learn what genes, DNA and chromosomes are and how they combine to make the human genome. You will also learn how the principles of inheritance work, the effect that our genetic make-up has on health, and how genetic material is passed on from generation to generation. This unit is an adapted extract from the course Author(s): Learning outcomes After studying this unit you should understand: how the linear sequence of DNA within a gene is related to the linear sequence of amino acids of a protein how the information in DNA is carried via RNA to make a protein how RNA is synthesised from DNA by the process of transcription where the processes of transcription and translation occur within the cell Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: Learning outcomes After studying this unit you should understand: something of the role of a genetic counsellor and its non-directiveness the difference between pre-natal diagnosis, childhood testing and adult testing and give some examples of diseases that may be tested for the ethical and moral difficulties involved in making decisions on whether or not to carry out such tests Introduction This unit looks at three different uses of genetic testing: pre-natal diagnosis, childhood testing and adult testing. Such tests provide genetic information in the form of a predictive diagnosis, and as such are described as predictive tests. Pre-natal diagnosis uses techniques such as amniocentesis to test fetuses in the womb. For example, it is commonly offered to women over 35 to test for Down's syndrome. Childhood testing involves testing children for genetic diseases that may not
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Richard P. Feynman (1918–1988)
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Activity 24
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