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3.3 Spider silk

The presence of regions of helical and sheet-like structures within a protein will affect its properties in different ways: a particularly striking example of this is provided by spider silk.

Imagine a polymer that forms fibres stronger, by mass, than steel and can be processed from water at ambient temperature and low pressure. As a consequence of its biological origin, it is extremely environmentally friendly and totally recyclable. It may sound like science fiction, but this i
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1 Biological materials

Materials engineers have long recognised the impressive range and combination of properties offered by biological materials. Figure 1 shows some representative examples of the combination of tensile strength and toughness (measured by Young's modulus, or elastic modulus for polymers) offered by natural mat
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Introduction

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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5.9 Vibrating air column: standing waves in a cylindrical tube closed at one end

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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5.4 Vibrating string: normal modes of vibration

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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7.1 The subjective experience

Two of the properties of sound that we have examined from an objective stance, frequency and amplitude, have a fundamental importance to our appreciation of sound and music. In this section I want to look more closely at the subjective interpretation of these two properties of sound. I should stress that I am talking about sine-wave sounds in this section. The complex, non-sinusoidal sounds encountered in music add extra layers of complexity to the relationships I am discussing here.

Ke
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6.1 Defining amplitude

Another important property of a sine wave we need to be able to specify is its amplitude. In essence, the amplitude of a sine wave is its size. Unfortunately there are various ways of defining what is meant by the size of a sine wave, and you are likely to come across many of them in material you look at outside this unit. Before I explain what our definition is, it will help matters if we look at what is meant by the average value of a sine wave.

Figure 16 shows a sinusoidally a
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Learning outcomes

After studying this unit, you should be able to:

  • explain correctly the meaning of the emboldened terms in the main text and use them correctly in context;

  • describe simply what a pressure wave is and give a simple explanation of sound in terms of a travelling pressure wave;

  • explain ‘cycle’ in terms of an oscillating source and the pressure wave it produces;

  • relate amplitude (including peak-to-peak and r.m.s.), frequency, period a
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16.4 Managing for emergence and self-organisation

It might be useful to re-read Box 4 before starting this section. In this example, the terms ‘open’ and ‘closed’ were used on several occasions. You have already encountered the term ‘closed system’. You were told that human beings are closed systems in terms of inputs to
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6.3 Clarifying purposefulness

Research conducted by Ralph Stacey (1993) shows how business managers often behave in a way contrary to espoused policies and expectations. Rather than adhering to conventions of long-term planning, and accepted orthodoxies and procedures, they actually tend to make a succession of unrelated, adaptive responses to changing situations as the need arises. This is often, and rather disparagingly, labelled muddle-through or crisis management but can result in adaptive action and organisation.


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6.2 Modes of managing systemically

Now I want to describe some of the possibilities I see as being available in the repertoire of an aware systems practitioner able to connect with the history of systems thinking and with the new theories of complexity.

David Robertson, in a presentation to the Society for Research into Higher Education in late 1998 entitled ‘What employers really, really want’ reported that: ‘research on employers in a number of English-speaking countries (an elite survey with senior corporate peo
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3.5 Distinctions about systems practice

A tension has existed throughout the history of Western thought around whether to focus on parts or the whole. The practice that springs from this history carries the same tension. This tension has been particularly visible within science and philosophy for a long time and it gives rise to different approaches. I will be addressing these tensions in Author(s): The Open University

9.8 Diagramming a complex situation

Diagrams are never an end in themselves. They have a purpose. They exist in relation to a situation and can be used to cast light upon aspects of that situation or to explain it to someone.

So, the next step is to look at the diagrams you have drawn and to ask yourself what you have learned about the situation. This answer may be in terms of a deeper appreciation of the situation. It may also be in terms of pointers towards possible interventions and some idea of the likely effects of s
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Part 2: 1 Introduction

I have a number of purposes in mind as I write Part 2. You can read these in conjunction with Figure 4.


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14 Part 2: 5 Self-assessment questions

SAQ 4

What are the four main factors that motivate individuals to invent?

Answer

Individuals are motivated to invent by one or more factors:

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11.5.2 Transfer

Transfer is where a technology, manufacturing process or material is transferred to another field to provide the basis for an invention. Earlier we saw how laser technology, originally thought to have few practical uses, was transferred to a variety of different applications including surgery, welding and cutting metal, bar-code readers, and audio CDs.


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11.5.1 Adaptation

Adaptation is where a solution to a problem in one field is found by adapting an existing solution or a technical principle from another. For example Karl Dahlman adapted the hovercraft principle embodied in land and sea vehicles for use in the first hover lawn mower, the Flymo, in 1963 (Author(s): The Open University

11.3 Step 2 – exploration

This is the period when, following the identification of the problem, attempts are made to understand it better and to make a stab at designing a solution. This might be a short process or it could take years and involve a detailed search for information, experimenting with different designs, even redefining the problem as a result of this activity.

Alexander Graham Bell adopted a problem-focused strategy when exploring the problem of designing a working telephone. This strategy is one
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10.10 Government policy, legislation and regulations

To a certain extent it's possible for governments to stimulate invention by providing incentives for manufacturers to develop new products and for consumers to buy and use them. One example of this process is in the field of vehicles powered by alternative fuels.

In the USA the Energy Policy Act of 1992 (EPAct) was passed to reduce US dependence on imported petroleum. The EPAct required federal and governmental departments with fleets over a certain size to acquire a percentage of alter
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