6.3 Some issues for consideration

DEMOCS offer a novel, and perhaps unique approach to public participation on contentious science issues. But how far is the process capable of dealing with the difficulties and uncertainties raised in the examples of engagement processes already considered in this unit, and what benefits might it bring? For example:

  1. How far is this process of group discussion likely to lead to outcomes that are representative of ‘public’ opinion?


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3.4 Consensus conference on plant biotechnology

The first UKNCC (at Regent's College) was hosted by the Science Museum and funded by the Biotechnology and Biological Sciences Research Council (BBSRC). The conference was based on a procedural model developed by the Danish Board of Technology. In Denmark, consensus conferences are held regularly and can be seen to have had unequivocal effects on policy making. Indeed, in a number of instances, Parliament has explicitly incorporated lay-panel recommendations in legislation. For example, lay-p
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2 Summary

Despite claims made for its potential, wave energy can never make any significant contribution to global energy supplies, although it may find a use in coastal communities. The greatest potential from wave energy exists far from shore, but waves are wind-dependent and so supplies are bound to be irregular.


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3.2 Structural domains

Structural domains can serve as spacers, which position other domains in an appropriate orientation or location, or they may permit movement of domains relative to each other. Examples of domains that function as spacers are the heavy and light immunoglobulin constant domains which ‘present’ the working end of the immunoglobulin, i.e. the variable domains, for binding to target antigen (Author(s): The Open University

8.6 Line spectra: Activity 8 Quasar redshifts

Activity 8: Quasar redshifts

Read Peterson section 1.3.5 (pages 16 and 17) by clicking the link below.

Learning outcomes

After studying this unit you should be able to:

  • explain the meaning of all the newly defined (emboldened) terms introduced in this unit;

  • draw, analyse and interpret position–time, displacement–time, velocity–time and acceleration–time graphs. Where appropriate, you should also be able to relate those graphs one to another and to the functions or equations that describe them, particularly in the case of straight-line graphs;

  • find the derivati
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3.1 The origins of domesticated dogs

Archaeologists and biologists agree that dogs (Canis familiaris) were the first species to become domesticated. Francis Galton, Darwin's younger cousin, suggested at the end of the 19th century that domestication began when humans captured and raised wolf puppies. The resulting adults ate scraps of human food, assisted in hunting and acted as guard dogs around camps. Among the evidence in support of this hypothesis is the observation that tribal people all over the world take wild anim
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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 mater
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3.3 Variation

Fossil rodents are first found in rocks that date from around 65 million years ago (from the Eocene) and are thought to have evolved from insectivore/omnivore-type mammals that lived 100 million years ago (in the Cretaceous period). To say that they evolved from simply means that there probably is a direct line of descent but that the descendants have changed from their forebears. One of the most significant ways that evolutionary change can be brought about is by a process known as na
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5.4 Older Cover

Moving up succession, the next lithotectonic unit is the Older Cover. By referring to Figure 9 and Table 2 in conjunction with the
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7.1 The ascending auditory pathway

Up till now we have dealt with the anatomy of the auditory periphery and how the basic attributes of sound are coded within the auditory periphery. A great deal of additional processing takes place in the neural centres that lie in the auditory brainstem and cerebral cortex. Because localisation and other binaural perceptions depend on the interaction of information arriving at the two ears, we need to study the central auditory centres, since auditory nerves from the two cochleae interact on
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6.3 Summary of Sections 4 to 6

Hair cells do not have axons and therefore do not generate action potentials.

The nerve that communicates with or innervates the hair cells along the basilar membrane is known as the vestibulocochlear nerve or VIIIth cranial nerve. The cochlear portion of the nerve contains afferent fibres that carry information in the form of action potentials from the organ of Corti to the brain, and efferent fibres that bring information from the cerebral cortex to the periphery.

Most of the af
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6.2 Number of neurons hypothesis

In addition to an increase in firing rate of neurons with differing dynamic ranges, the inclusion of discharges from many fibres whose CFs are different from those of the stimulus may also help to account for the wide dynamic range of the ear. You know from Section 3.3 that in response to a pure tone stimulus the basilar membrane vibrates maximally at a g
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6.1 Firing-rate hypothesis

Information about stimulus intensity is encoded in two ways: the firing rates of neurons and the number of active neurons.

Intensity is assumed to be encoded by an increase in discharge rate of action potentials within the auditory system. As the stimulus gets more intense, the basilar membrane vibrates at a greater amplitude causing the membrane potential of activated hair cells to be more depolarised and this causes the nerve fibres that synapse onto the hair cells to fire at a greate
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5.2 Frequency code

Although the evidence for the place theory of frequency coding is compelling, there is some question as to whether the tuning curves obtained from neurons in the auditory nerve provide a mechanism for frequency discrimination that is fine enough to account for behavioural data. People can detect remarkably small differences in frequency – in some cases as small as 3 Hz (for a 1000 Hz signal at moderate intensity). What accounts for this ability? As early as 1930, the American experimental p
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5.1 Place code

We know that each hair cell occurs in a localised region of the cochlea, and that auditory nerve fibres contacting each hair cell fire action potentials in response to movement of the basilar membrane at that location. This means that the response of any given fibre should reflect the frequency selectivity of that location on the basilar membrane from which it comes. In other words, cochlear nerve fibres preserve the frequency selectivity found along the basilar membrane. Fibres on the outsid
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3.7.1 Summary of Sections 3.4 to 3.7

Hair cells are found in the organ of Corti and run the length of the basilar membrane. They transform mechanical energy into neural signals.

When the basilar membrane vibrates in response to sound, hair cells located at the site of maximal vibration on the basilar membrane are stimulated. This means that the mechanical properties of the membrane allow the auditory system to distinguish one frequency from another by the location on the membrane that is maximally excited by a particular f
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3.6 Synaptic transmission from hair cells

In addition to being sensory receptors, hair cells are also presynaptic terminals. The membrane at the base of each hair cell contains several presynaptic active zones, where chemical neurotransmitter is released. When the hair cells are depolarised, chemical transmitter is released from the hair cells to the cells of the auditory nerve fibres. Excited by this chemical transmitter, the afferent nerve fibres contacting the hair cells fire a pattern of action potentials that encode features of
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3.5.2 Mechanical force directly opens and closes transduction channels

It is believed that tip links aid in causing ‘channels’ to open and close near the top of the hair cell (Figure 16). Tip links are filamentous connections between two stereocilia. Each tip link is a fine fibre obliquely joining the distal end of one stereocilium to the side of the longest adjacent process. It is thought that each l
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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 betw
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