4.4 Incorporating substantial equivalence into national and international law The concept of substantial equivalence very quickly became important in international trade law. The WTO aims to harmonise national food standards to meet international norms. Under its rules, a country could be penalised if it imposed food standards more stringent than those agreed internationally. In this context, international food standards are set by the Codex Alimentarius Commission (Table 1). In 1996, a report was issued within the Codex framework, which endorsed the principle of subst
4.2 Scientific risk analysis In the context of national and international legislation on the safety of food and animal feed, much of the thinking about assessing risk has come from the experience of developing legislation to cover potentially toxic chemicals. In this regard, the terms ‘risk’ and ‘hazard’ are particularly important. ENTRANSFOOD (European network safety assessment of genetically modified food crops) has defined the terms as follows: 2.2 What is natural? Many critics of GM feel that the techniques reflect an unwelcome form of ‘tampering with nature’. This is a particular concern of some consumers with respect to food. Such a view is sometimes scornfully interpreted as an expression of what is called the ‘naturalistic fallacy’ – a belief that equates morality with naturalness, seeing what is natural as ‘right’. But concerns about GM foods may reflect a more reasoned and defensible position. It might be argued that consumers are n 2.5 Using stars to probe the interstellar medium The effects of interstellar material on starlight can be used to probe the properties of the interstellar medium itself. A few examples are: The presence of particular interstellar atoms or molecules may be determined by identifying the observed spectral lines or bands. The temperature of the gas may be determined from the relative strengths of different lines or bands produced by different energy state changes of the same atom or mol 1.1 Constructing the H–R diagram Three properties which are suitable for comparing stars are temperature, luminosity and radius. However, we don't need all three. Why not? 6 Phylogeny and cladistic analysis In Section 3.3 the point was made that many physiologists consider that desert birds are successful because of their avian physiology, not because of any specific adaptations. While Williams and Tieleman's research on hoopoe larks demonstrated that desert species are capable of flexibility in metabolic rate and evaporative water loss, it suggested that adaptation is important too. The selective advantages of lowered BMR and TEWL for desert birds include reduced energy demand, and lower produc 3.2 Integration of anatomy and behaviour with biochemical and physiological strategies in evaders We know from Section 2.3 that small desert rodents remain cool by staying in their burrows for all or part of the day. Kangaroo rats (Dipodomys spp.; see Figure 20 in Section 2.3) depend on metabolic water as there is little or no water available in their diet of seeds. Kangaroo rats appear to be ill-adapted for 2.2 How animals interact with the environment is affected by their body size Willmer et al. (2000) classify desert animals in terms of the range of body sizes and the rate of evaporation (Figure 8). 2.4 Summary Adaptive hypothermia occurs widely in both mammals and birds, but the ability is scattered throughout different families: even within single families, some species show torpor and some do not, suggesting that the ability may have evolved independently many times. Whereas a number of small birds show a daily, shallow torpor, so far only the poor will has been described as showing extended bouts of torpor comparable to those seen in mammals. Species of birds and mammals that hibernate (Figures 2.1 Degrees of torpor Adaptive hypothermia occurs in at least six distantly related mammalian orders (Table 1) and in several orders of birds. There is a spectrum running from those species which can tolerate a drop in T
b by 2° C for a few hours, to the seasonal deep hibernators which maintain a T
b as low as 4° C for weeks on end. Learning outcomes By the end of this unit you should be able to: define and use, or recognize definitions and applications of, each of the bold terms; give definitions of the terms ‘hibernation’, ‘torpor’ and ‘adaptive hypothermia’, and the three physiological processes that underlie them; give examples of the diversity of the major groups of mammals and birds that contain hibernating species; describe the physiological changes occur 3.5 The structure of adipose tissue Since food is only available seasonally or intermittently at high latitudes, many arctic birds and mammals, including polar bears, Svalbard reindeer, arctic foxes, seals and walruses, naturally accumulate large stores of fat. The quantity of energy stored and the metabolic control of its use are finely adjusted to the habits and habitat of the species. This section is concerned with the cellular structure and anatomical organization of adipose tissue in such naturally obese species. Most labo 4.5.6 Catalyst deterioration: summary An ability to withstand mild deactivation is built into the design of the catalytic converter. However, severe deactivation could prevent the system from meeting emissions legislation. The major causes of deactivation are thermal damage and poisoning. High temperatures may cause sintering of the metals and/or the support; this can be prevented to some extent by the addition of ceria as a structural promoter. Damaging interaction 4.5.4 Phosphorus Phosphorus is recognised as a potential poison for automotive catalysts. The phosphorus level in fuel is generally very low (2×10−5 g l−1), but it is present in higher concentrations in engine oils (1.2 g l−1). Phosphorus derived from the engine oil is believed to react with the alumina support, and also to reduce the activity of the noble metal component. This deactivation is particularly important for Pd, with which phosphorus may form an all Introduction Ensuring good quality air is essential for the protection of public health. Governments worldwide have adopted a range of increasingly demanding measures to curb air pollution with a particular focus on the emissions from motor vehicles. An important part of this strategy has been the development of the three-way catalytic converter to remove exhaust pollutants such as carbon monoxide, unburnt hydrocarbons and nitrogen oxides. This unit takes an in-depth look at the construction of this conve 9.1 The psychological arena The examples in the previous section followed the traditional medical approach, namely that there is a disease, it can be diagnosed (identified), and the cause of the disease, be it viruses, bacteria, pathogens, genes or poisons, can be sought. This section moves away from the medical arena and into the psychological arena, where the symptoms are behavioural. In this case, the symptoms are socially unacceptable behaviour and to the list of causes just mentioned is added family circumstances a 7.8 Summary of Section 7 This section has sought to illustrate the formation of connections between neurons and their targets by exploring a few examples. The picture that emerges is one of cells at different stages of development subjected to a vast array of signals. These signals are the medium through which environmental factors exert their effects. To some of these signals, some cells respond; to other signals, other cells respond. What a cell, a neuroblast, a growth cone actually does is dependent on the combina 6.5 Summary of Section 6 Growth cones respond to proximal and distal cues. The proximal cues in the extracellular matrix or other cells affect adhesion and result in chemotactic guidance. Distal cues are also in the extracellular matrix but they diffuse through it and result in the growth cone either moving towards the source (attractants) or away from it (repellants). These distal cues are chemotropic cues and can have different effects on different growth cones; what may be an attractant to one growth cone may be r 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. Learning outcomes After studying this unit you should be able to: recognise definitions and applications of each of the terms printed in bold in the text; critically evaluate statements about the influence of the genome on behaviour; explain the ways in which genetic and environmental factors influence the development of the nervous system; provide examples of the influence of genetic and environmental factors on the development of the nervous s
Question 1
Table 1 Groups o
