The median of a sample of data with an odd number of data values is defined to be the middle value of t]]> After studying this unit you should be able to:

Part A

• understand the European Convention of Human Rights system of rights and the mechanism set up for their protection:

• You have seen that the ECHR emerged from the social and political aftermath of the Second World War. It emphasises individual rights and tries to provide a balance between specific individual and collective rights. Som]]> After studying this unit you should be able to:

  Part A

  • understand the European Convention of Human Rights system of rights and the mechanism set up for their protection:

  • You have seen that the ECHR emerged from the social and political aftermath of the Second World War. It emphasises individual rights and tries to provide a balance between specific individual and collective rights. Som]]> 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]]> 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]]>

  • 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]]>

  • 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]]> 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:

    Figures

    Figure 2 Nortier, P. and Soustelle, M. (1987) 'Alumina carriers for automotive pollution control', in Cruecq, A. and Frennet, A. (eds) Catalysis and Automotive Pollution Control, Elsevier Science Publishers;

    Fi]]> 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:

    Figures

    Figure 2 Nortier, P. and Soustelle, M. (1987) 'Alumina carriers for automotive pollution control', in Cruecq, A. and Frennet, A. (eds) Catalysis and Automotive Pollution Control, Elsevier Science Publishers;

    Fi]]> This unit is the third in a series of three on Animals at the extreme. In order to get the most from it you should have previously studiedAnimals at the extreme: the desert environment (S324_1)andAnimals at the extreme: hibernation and torpor

    This unit is from our archive and is an adapted extract from Animal physiology (S324) which is no longer taught by The Open University. If you want to study formally with us, you may wish to explore other courses we offer in <]]> This unit is the third in a series of three on Animals at the extreme. In order to get the most from it you should have previously studiedAnimals at the extreme: the desert environment (S324_1)andAnimals at the extreme: hibernation and torpor

    This unit is from our archive and is an adapted extract from Animal physiology (S324) which is no longer taught by The Open University. If you want to study formally with us, you may wish to explore other courses we offer in <]]> 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;

    • outline the special features of the polar regions as a habitat and list some contrasts between the Arctic and the Antarctic;

    • describe some effects of daylength on feeding, fat deposition and reproduction in arctic animals;

    • explain why the environmental controls of appetite, activity level and fecun]]> 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;

      • outline the special features of the polar regions as a habitat and list some contrasts between the Arctic and the Antarctic;

      • describe some effects of daylength on feeding, fat deposition and reproduction in arctic animals;

      • explain why the environmental controls of appetite, activity level and fecun]]> This unit is about animals' structural and physiological adaptations to living permanently in cold climates; hibernation, a special response to transient or seasonal cold, is described in the openlearn unitAnimals at the extremes: hibernation and torpor (S324_2). Living in a polar climate involves adaptations of many physiological systems: appetite, diet, energy storage and reproductive habits as well as thermoregulation. In many cases, such changes involve ‘ordinary’ physio]]> This unit is about animals' structural and physiological adaptations to living permanently in cold climates; hibernation, a special response to transient or seasonal cold, is described in the openlearn unitAnimals at the extremes: hibernation and torpor (S324_2). Living in a polar climate involves adaptations of many physiological systems: appetite, diet, energy storage and reproductive habits as well as thermoregulation. In many cases, such changes involve ‘ordinary’ physio]]> At high latitudes, the Sun's rays always strike the Earth at a large angle from the vertical so they travel through a thicker layer of atmosphere and are attenuated by the time they reach the ground. Because the Earth's axis of rotation is inclined to its path around the Sun, there are large seasonal changes in daylength and the Sun is continuously below the horizon for a period in winter and continuously above the horizon for an equivalent period in summer. The annual changes in daylength an]]> At high latitudes, the Sun's rays always strike the Earth at a large angle from the vertical so they travel through a thicker layer of atmosphere and are attenuated by the time they reach the ground. Because the Earth's axis of rotation is inclined to its path around the Sun, there are large seasonal changes in daylength and the Sun is continuously below the horizon for a period in winter and continuously above the horizon for an equivalent period in summer. The annual changes in daylength an]]> All plants and animals respond to environmental changes such as the light–dark cycle and temperature, but the impact of the environment on essential physiological processes such as eating, fattening and breeding is more evident and often more finely controlled in polar species than in those that are native to warmer and more equable habitats. Large effects are nearly always easier to quantify and to investigate experimentally, so arctic species offer an excellent opportunity to study the su]]> All plants and animals respond to environmental changes such as the light–dark cycle and temperature, but the impact of the environment on essential physiological processes such as eating, fattening and breeding is more evident and often more finely controlled in polar species than in those that are native to warmer and more equable habitats. Large effects are nearly always easier to quantify and to investigate experimentally, so arctic species offer an excellent opportunity to study the su]]> Birds do not hibernate, but like reindeer, many species undergo daily or seasonal changes in energy expenditure and appetite, and many of the endocrine changes that are an integral part of true hibernation in other groups. The fact that the preliminary stages of hibernation are widespread among vertebrates may help to explain why true hibernation has evolved several times in distantly related taxa. Instead of hibernating, some species of birds migrate to and from breeding areas, where they ar]]> Birds do not hibernate, but like reindeer, many species undergo daily or seasonal changes in energy expenditure and appetite, and many of the endocrine changes that are an integral part of true hibernation in other groups. The fact that the preliminary stages of hibernation are widespread among vertebrates may help to explain why true hibernation has evolved several times in distantly related taxa. Instead of hibernating, some species of birds migrate to and from breeding areas, where they ar]]> As pointed out in Section 1.1, primary plant productivity occurs for only a few months in the summer, so the reproductive physiology of most arctic animals, particularly herbivorous species, is tightly synchronized with the seasons. On Svalbard (Figure 2b), more than 90% of the reindeer fawns are born in the first week of J]]> As pointed out in Section 1.1, primary plant productivity occurs for only a few months in the summer, so the reproductive physiology of most arctic animals, particularly herbivorous species, is tightly synchronized with the seasons. On Svalbard (Figure 2b), more than 90% of the reindeer fawns are born in the first week of J]]> The food supply for most polar species depends on several unpredictable factors so successful breeding is far from certain, even if births are tightly synchronized with the seasons. Maintaining pregnancy and feeding the offspring after birth (or hatching in birds) are energetically expensive. The death of the offspring before its maturity represents an irredeemable loss of ‘reproductive investment’ for the parents, particularly the mother, although the earlier in parental nurturing that t]]> The food supply for most polar species depends on several unpredictable factors so successful breeding is far from certain, even if births are tightly synchronized with the seasons. Maintaining pregnancy and feeding the offspring after birth (or hatching in birds) are energetically expensive. The death of the offspring before its maturity represents an irredeemable loss of ‘reproductive investment’ for the parents, particularly the mother, although the earlier in parental nurturing that t]]>