Humans use language to communicate. This is an obvious statement, but what is language and how do we use it? Language is basically a set of symbols with associated meanings. These symbols are delivered using a set of rules for stringing the symbols together to generate additional meaning. Humans use mostly sounds to represent these symbols, although as an Italian I can communicate common meanings by only using a range of hand gestures! We string together phonetic sounds to make words, and we
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This study unit introduces you to the proposition that our mental models change through learning, and
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The third category of thermal effects identified in Section 2 are those associated with sudden changes. Here are some technically important examples where things change suddenly at a particular temperature:

• Pure water boils at 100 Â°C (at atmospheric pressure).<
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• Thermal energy is a random thing, so any group of particles possessing it will have a distribution of kinetic energies.

• The fraction of particles with energy greater than an amount Eï»¿1 is proportional to exp(âˆ’Eï»¿1/kT).

• Thermally activated rates follow Arrhenius's law and are characterised by an activation energy.

• Diffusion in solids and electrical conduction i
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The final trick I want to show you with Arrhenius's law is how to extract the constants rï»¿0 and Eï»¿a from experimental data. If the Arrhenius equation (Section 4.3.1) is â€˜turned inside outâ€™ by taking natural logarithms of both sides it becomes:

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Temperature is, of course, the measure of â€˜thermalâ€™ conditions. Nowadays it is measured by thermometers and expressed as a number on an agreed scale. Some features of thermometers and of their use are discussed in Thermometers and process control

The theoretical construct of temperature relates it to the kinetic energies of atoms. This gives clear insights into the way temperature affects the behaviour of materials. Energy is given to things to make them hot and taken
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Once a small number of chains have been started, propagation involves successive addition of monomer units to achieve chain growth. At each step the free radical is regenerated as it reacts with the double bond. So in the case of styrene the propagation step is

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Initiation is the mechanism which starts the polymerization process. Vinyl monomers are quite easily polymerized by a variety of activating methods. Styrene, for example, can be converted to solid polymer simply by heating, and ultraviolet light can have exactly the same effect. Usually, however, an activating agent is used. This is an unstable chemical which produces active species that attack the monomer. A good example is benzoyl peroxide which splits up when heated:

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The aims of systems engineering can be divided into those to do with its outputs and those associated with the process itself. As far as its outputs are concerned, systems engineering aims to ensure that:

• the requirements of all the stakeholders are taken into account in engineering the system

• the system, as engineered and realised, meets the requirements of stakeholders

• the system, while meeting the req
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The conceptual (or activity) model contains all the activities that the relevant system would have to perform. The model is usually drawn as a block diagram.

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The basic optical-fibre link consisted of the source (laser or LED), the fibre and the detector, as was shown in Figure 1. Improvements in these components can increase the data rate, but the system is still a point-to-point transmission link and all signal processing, such as routeing
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This unit is from our archive and it is an adapted extract from Digital Communications (T305) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this curriculum area.

By using optical fibre, very high data rates (gigabits per second and higher) can be transmitted over long d
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Activity 8

Read the excerpts of Plato's Protagoras highlighted in the version attached below. Jot down a few ideas about the final vocabulary that Socrates uses in the dialogue.

The secondary category of defects observed by Law and his team refer to defects of fitment of the columns and braces together during construction of the bridge. He noted many bolt holes had been deliberately enlarged, but why this was necessary remains unclear, especially as the bolts were 0.125 inch smaller than the holes. Perhaps burrs or points in the holes needed removal before the bolts would fit correctly. The quadrants also came in for criticism for their poor fit to the columns, and i
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Experiments showed that the use of paper tape coated with iron oxide particles significantly improved the signal-to-noise ratio and enabled a lower tape speed to be used. A plastic-based version of this magnetic tape, developed by the German company BASF, led to the development of a commercial tape recorder with audio characteristics that could nearly match those of the gramophone record, but not at an economical price. Secret work on tape recorders was undertaken by the Germans throug
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Berliner was aware that Edison had problems duplicating cylinders. Initially copies were made from a master cylinder using a mechanical engraving process. Unfortunately this method caused the master cylinder to wear out after making just a few copies, so performers had to be asked to record several masters to ensure enough cylinders could be duplicated. An improved recording system allowed multiple master cylinders to be made by feeding several recording phonographs from one horn, but the cyl
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This unit examines how self-assembled structures based on lipids and proteins provide a framework for cellular processes.

This unit is an adapted extract from the Open University course Engineering small worlds: micro and nano technologies (T356).

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The third configuration of air column that we shall consider is that enclosed by a conical tube. Figure 17 shows the normal modes of vibration for a conical tube plotted in terms of pressure. As you would expect, there is a pressure antinode at the closed tip of the cone and a pressure node at the open end
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We'll now turn our attention to the setting up of standing waves in an air column contained within a cylindrical tube that is open at one end but closed at the other. Straight away we can say that the closed end must be a displacement node since the air molecules can't move at this boundary. That means it must be a pressure antinode. The open end, as we saw previously, will be a displacement antinode (that is, a pressure node).

Now, you may recall that the distance between a node and a
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The frequencies at which standing waves can be set up on a string are the string's natural frequencies. They can be determined quite easily. The first thing to note is that the end of the string being held by the person is tightly gripped so any pulse or wave that returns to the person's hand will be reflected and inverted. Therefore both ends of the string can be considered to be fixed and so must be at nodes of the standing wave. But you learned earlier that the distance between adjacent no
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