Substituting the assumed form of the electric field (Equation 7.20) into the empty-space version of Gauss's law (Equation 7.16) gives

The first two partial derivatives are equal to zero because f does not depend on x or y. So we obtain

Author(s): The Open University

Then he was a sheâ€¦

(Lou Reed, American rock singer)

In 1996, a book called Our Stolen Future was published, bringing to public attention a debate that had been simmering among biologists for some time. Written by Theo Colborn and two colleagues at the World Wildlife Fund (WWF), this book presented the hypothesis that certain industrial chemicals, commonly found as environmental pol
Author(s): The Open University

If you have less than one unit you should put a zero before the decimal point to make it easier for yourself and others to read the value (e.g. you should write 0.4 rather than just .4, as will be explained later in this unit). However, how many zeros should you put after the last whole number in the series? For instance, is 0.4 the same as 0.40?

The short answer is that on one level, it is. However, by writing 0.40 we are saying that there are four tenths and zero hundredths, an
Author(s): The Open University

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
Author(s): The Open University

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): The Open University

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): The Open University

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 (20â€“1500 Hz) and interaural intensity cues, which are important for high-frequency sounds (1500â€“20 000 Hz). The frequency responses in the superior olive reflect these differences. The medial superior olive includes neurons that are responsiv
Author(s): The Open University

## Question 1

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.

### AnswerAuthor(s): The Open UniversityLicense informationRelated contentExcept for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

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
Author(s): The Open University

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.

Author(s): The Open University

## Richard P. Feynman (1918â€“1988)

Author(s): The Open University

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:

## FiguresAuthor(s): The Open UniversityLicense informationRelated contentExcept for third party materials and/or otherwise stated (see terms and conditions) the content in OpenLearn is released for use under the terms of the Creative Commons Attribution-NonCommercial-Share

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 â€“ 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
Author(s): The Open University

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:

Author(s): The Open University

Azzam, N. A., Hallenbeck, J. M. and Kachar, B. (2000) Membrane changes during hibernation. Nature, 407, 317â€“318.
Boutilier, R. G. and St-Pierre, J. (2002) Adaptive plasticity of skeletal muscle energetics in hibernating frogs: mitochondrial proton leak during metabolic depression. Journal of Experimental Biology, 205, 2287â€“2296.
Buck, C. L. an
Author(s): The Open University

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.

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Author(s): The Open University

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.

Author(s): The Open University

Both vitamins and minerals are essential in the diet in small quantities and so they are often grouped together as micronutrients.

### Activity 24

Which items in the diet are classified as macronutrients?

Author(s): The Open University

Genes are units of inheritance that contribute to a personâ€™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): The Open University

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

Author(s): The Open University