4.4 Genetic diversity and mass extinctions It is for this reason that there are now international agreements on the need to work together to retain genetic diversity in all species and, more generally, biological diversity (species and habitat diversity). From a Learning outcomes After studying this unit you should be able to: Define and use, or recognize definitions and applications of, each of the terms in bold in the text. Understand the complexity of the interdependence between organisms and their environment. Describe some of the consequences for health of pollution. Explain why it is difficult to gain international agreements to secure biodiversity and reduce pollution. 4 4 Renewable energy sources Fossil and nuclear fuels are often described as non-renewable because supplies are finite and will eventually run out. Renewable fuels are those energy sources that will not run out in the future. Most renewable energy sources originate from the sun (solar energy), while tidal energy originates from the gravitational pull of the moon, and geothermal energy results from heat trapped below the surface of our planet. Solar energy can be used directl Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence The material acknowledged below is contained in: Ordering the International: History, Change and Transformation (eds William B 2.3 Divisions that matter: thinking through territories Without losing our focus on the planet as a whole, it is time now to return to what Paani Laupepa from Tuvalu refers to as the ‘front line’ of climate change: those islands that are particularly vulnerable to rising sea level and associated climatic hazards (Lynas, 2003). It has often been said that low-lying coral islands like Tuvalu or Kiribas in the Pacific Ocean, or the Maldives in the Indian Ocean, are acting as a kind of early warning system for global climate change. Sea level is e 1.1Aim The aim of this section is to practise the use of diagramming techniques as part of a fundamental shift in interpreting issues – from an assembly of static objects to a network of dynamic relationships. 5.1 Why is it important to be organised? 87 per cent of items that are filed into a filing cabinet are never looked at again. STANFORD UNIVERSITY
In 2010, the world’s digital information output was estimated to pass 1.2zettabytes – A zettabyte is a new term which equals a thousand billion gigabytes. UNIVERSITY OF CALIFORNIA (BERKELEY)
A new blog is created every second. TECHNORATI
10 per cent of salary cos 4.3 R is for Relevance Relevance is an important factor to consider when you are evaluating information. It isn’t so much a property of the information itself but of the relationship it has with your question or your ‘information need’. For example, if you are writing an essay about robotics a book or website about green energy would probably not be relevant. So there are a number of ways in which a piece of information may not be relevant to your query: geographical 4.2 P is for Presentation By presentation, we mean, the way in which the information is communicated. You might want to ask yourself: Is the language clear and easy to understand? Is the information clearly laid out so that it is easy to read? Are the fonts large enough and clear? Are the colours effective? (e.g. white or yellow on black can be difficult to read) If there are graphics or photos, do they help 2.3.4 The contract team The contract team is brought in from outside in order to do the project work. Here, the responsibility to deliver the project rests very firmly with the project manager. The client will find such a team harder to control directly. On the other hand, it is the client who will judge the success of the project, so the project manager has to keep an eye constantly on the physical outcomes of the project. A variant of this is the so-called ‘outsourced supply team’, which simply means that the 4.3.4 Ionic polymerization Free radicals are indiscriminate in the compounds they attack, and their non-selective nature in polymerization reactions leads to problems such as chain branching and transfer which affect the structure of the polymer produced. Anionic polymerization overcomes many of these problems. A typical commercial (but also see Box 8 2.3.1 Structural isomerism In the saturated hydrocarbons, whose structural formulae are shown in Figure 16, it is not possible to form distinct isomers with just three or less carbon atoms linked together. There is only one way in which one carbon and four hydrogen atoms can be linked together, the single compound being methane, CH4. A simila 6 Summary This unit has covered the background to systems engineering. It began by addressing the question ‘Why is systems engineering important?’ Two reasons were discussed: projects go wrong, and the increasing incorporation of software means that they go wrong more often now than in the past complication, complexity and risk are all increasing and need to be managed. In the second section I examined the development of en 5.2 The aims and principles of system engineering 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 5.1 Introduction: the general framework The general framework of systems engineering adopted in the course consists of: a hierarchy of elements; aims associated within its outputs and process; a set of principles; a division into technical and managerial components of the process. The lexicon of system engineering used in the course contains the hierarchy of elements:
strategy: meaning the accumulated decisions concerning the areas in which an organisation operates and its lon 3.4 Systems concepts: structure As suggested earlier, the structure of a system is its functional or physical arrangement; the term that is often used in systems engineering is ‘architecture’. The architecture of a system can be deconstructed to reveal its constituent elements. I suggested in Section 1 that an existing knowledge base has an important bearing on the way in which a change problem is perceived. The way that this is conceived by one armaments system integrator is illustrated in 4.5.2 10 Gigabit Ethernet The standard for 10 Gigabit Ethernet (IEEE 802.3ae, lOGbE) was approved in July 2002. The main use of lOGbE, initially at least, is for backbone networks which interconnect 10, 100 or 1000 Mbit/s Ethernet hubs. These hubs might be widely separated geographically, so the standard includes physical layer specifications specifically for WAN (wide area network) applications as well as LAN applications. The WAN specification is for operation at slightly under 10 Gbit/s, 9.95328 Gbit/s, so as to be 2.4 Pulse spreading and bandwidth Calculate the maximum signalling rate given by the Nyquist rate for the 1550 nm window, assuming that it runs from 1450 nm to 1610 nm. Using the 8.4 Stopping the etch Just as important as being able to remove material is being able to stop doing so once the intended etch depth has been reached. Success or failure in this aspect of etching determines whether or not any of the benefits of parallel processing of thousands of devices will be obtained. Uniformity of result from device to device, and repeatability from wafer to wafer, are crucial to the economic viability of the whole exercise. There are three broad categories of approach to this problem:< 8.3.6 Deep silicon etching MEMS structures often require etching to a much greater depth than is needed for microelectronics. A rate of 1–2 μm min−1 may be quite sufficient for making transistors less than 1 mm deep, but to etch through 600 mm of silicon to form an accelerometer would take all day. The advent of MEMS and wafer-level packaging applications, therefore, brought a need for yet faster anisotropic etches, requiring advances both in the process and in the etching equipment. Capacitive co
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