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The Sustainable Development Goals (SDGs) are presented as highly connected: an ‘interrelated’ and ‘indivisible’ agenda with a need for policy coherence for implementation. We analyse the relationships among the goals using formal systems analysis and find that the connections between goals are uneven, with a failure to integrate gender equality, peace and governance concerns. This incoherence may undermine policy initiatives aimed at developing approaches to implement the SDGs. The Sustainable Development Goals agenda is proposed as an interconnected framework that requires policy coherence for implementation. This study shows that the connections across goals are uneven and that gender equality, peace and governance concerns are not adequately integrated.

Faced with increasing rates of biodiversity loss and modest conservation budgets, it is essential that natural resource managers allocate their financial resources in a cost-effective manner and provide transparent evidence for extra funding. We developed the 'Cost-Effective Resource Allocator', a Microsoft Excel-based decision support tool to assist natural resource managers and policy makers, to prioritize the set of management strategies that maximize the total number of years that a suite of species is expected to persist given a budget constraint. We describe this tool using a case study of four locally threatened species from the Australian Commonwealth National Park of Christmas Island in the Indian Ocean. These include: a native fern (Pneumatopteris truncata), the Christmas Island Red Crab (Gecarcoidea natalis), the Golden Bosun (Phaethon lepturus fulvus), and Abbott's Booby (Papasula abbotti). Under a hypothetical budget of 8,826,000 AUD over ten years, in which all species are considered equal, our tool recommends funding: fern propagation and planting, rat control, cat control, and Yellow Crazy Ant (Anoplolepis gracilipes) survey and control. We found that the cost-effectiveness rankings of these strategies were sensitive to the importance that assessors' assigned to different species. The 'Cost-Effective Resource Allocator' can accommodate input from up to eight assessors, and analyse a maximum of 50 management strategies for 30 species.

A new set of “Sustainable Development Goals” (SDGs) are currently being negotiated at the United Nations, and there is a widespread consensus that these goals must be “universal.” This article analyses what universality might mean in this context, and its normative significance as a guiding principle for the goals. After briefly introducing the Sustainable Development Goals as found in the current stage of the negotiations, thearticle proceeds in three sections that consider three different senses of universality. In the first, I outline the most intuitive or straightforward sense of universality as a claim about the scope of the goals, with limited import for the content. In the second section, I expand on this idea by noting a widespread understanding of the content of the goals which might also be thought universal and which reflects a moral cosmopolitan constraint on the ambition of each goal. Universality is paired with, and contrasted against, the need fordifferentiation. In the final section, I examine this idea of differentiation, asking how and how far, the goals should allow for country context. From this discussion arises a third account of universality which incorporates a demand for fair burden-sharing. I consider, and ultimately caution against, this account of universality, even though the demand forfairness is crucial in its own right.

The responsible development of new nanomaterials and nano-enabled products requires that potential risks are understood and managed before harms occur. Although quantitative and predictive tools for anticipating human health and environmental risk are in early stages of development, there is a clear need for screening methodologies to inform decision making related to nanomaterial risk management in regulatory agencies and industry. This paper presents the results of a two-day workshop with nanotechnology experts aimed at developing a risk-screening framework for nanomaterials. Drawing upon expertise in nanotoxicology, human exposure, environmental fate and transport, and structured decision making, participants developed a decision support framework relating key nanomaterial physicochemical and product characteristics to important hazard and exposure indicators. Application of the preliminary nano-risk-screening tool (NRST) to several test cases illustrates the utility of the approach for both identifying nanomaterial characteristics that drive risks and for highlighting opportunities to redesign products to minimize risks. This framework for aiding risk managers’ decisions under uncertainty provides the foundation for the development of a transparent and adaptable screening tool that can inform the management of potential risks.

The removal of arsenic bearing minerals from concentrates is becoming more important as environmental laws become ever stricter with regard to smelter emissions. The onus is shifting to concentrate producers to remove these minerals from their product, with penalties applying to materials containing greater than background amounts. The arsenic content of Rosebery copper flotation feed is mainly present as arsenopyrite (FeAsS), containing approximately 46.0% arsenic with the remainder of the arsenic in copper sulphosalts (tennantite (Cu12As4S13)), in a solid solution series with tetrahedrite (Cu12Sb4S13). Tennantite contains approximately 20.3% arsenic. Characterisation of the rougher and cleaner concentrates obtained during a plant survey showed that the arsenopyrite was appropriately rejected in the copper flotation circuit. However, tennantite showed similar flotation behaviour to the copper sulphide minerals so that the high arsenic content of the final copper concentrate was mainly in the copper sulphosalts. In this study, regrinding the copper rougher concentrate was investigated to reject tennantite in cleaner flotation. It was found that although finer grinding increased the mass fraction in the ultrafine fraction, the tennantite liberation only increased slightly. The copper selectivity against arsenic was improved significantly although the recovery of copper, silver and arsenic was lower. The difference in floatability of copper sulphide minerals and tennantite appears to increase at finer sizes. In this study, pH and Eh were also manipulated to further improve the selectivity of copper flotation against tennantite at fine particle sizes with some promise. In order to find an application in the Rosebery circuit, any changes must have a net economic benefit and the trade-offs and implications are discussed in this paper.

Arsenic is a toxic and volatile element that has little commercial use. This is causing some concern to copper smelters as they are obliged to dispose of arsenic materials produced as a by-product to the smelting process in accordance with ever tightening environmental guidelines. The onus is to move back to concentrate producers to remove toxic elements, such as arsenic, earlier in the concentrate supply chain. The common copper–arsenic bearing minerals in copper ores, enargite (Cu 3 AsS 4 ) and tennantite (Cu 12 As 4 S 13 ), contain significant amounts of copper; 48.4% and 51.6% respectively. Removal of these minerals from the concentrate removes valuable metal, hence income. There is a dearth of literature concerning the selective removal of enargite and tennantite from sulphide ores, but there are reports on some success using either chemical oxidation or potential control. These methodologies have been applied to ores from mines as they deepen where arsenic levels in concentrate are becoming prohibitive. In this paper copper–arsenic mineral removal from copper concentrates is reviewed.

Many environmental and risk management decisions are made jointly by technical experts and members of the public. Frequently, their task is to select from among management alternatives whose outcomes are subject to varying degrees of uncertainty. Although it is recognized that how this uncertainty is interpreted can significantly affect decision-making processes and choices, little research has examined similarities and differences between expert and public understandings of uncertainty. We present results from a web-based survey that directly compares expert and lay interpretations and understandings of different expressions of uncertainty in the context of evaluating the consequences of proposed environmental management actions. Participants responded to two hypothetical but realistic scenarios involving trade-offs between environmental and other objectives and were asked a series of questions about their comprehension of the uncertainty information, their preferred choice among the alternatives, and the associated difficulty and amount of effort. Results demonstrate that experts and laypersons tend to use presentations of numerical ranges and evaluative labels differently; interestingly, the observed differences between the two groups were not explained by differences in numeracy or concerns for the predicted environmental losses. These findings question many of the usual presumptions about how uncertainty should be presented as part of deliberative risk- and environmental-management processes.

In managing invasions and colonizations of non-native species, eradication or control efforts must proceed quickly. There are 2 challenges in taking such quick action. First, managers frequently have to choose among complex and often competing environmental, social, and economic objectives. Second, the effects are highly uncertain. We applied participatory structured decision making (SDM) to develop a response plan for the recent invasion of non-native myrtle rust (Uredo rangelii) in Australia. Structured decision making breaks a complex decision process into 5 steps: identify problems (i.e., decisions to be made), formulate objectives, develop management alternatives, estimate consequences of implementing those alternatives, and select preferred alternatives by evaluating trade-offs among alternatives. To determine the preferred mid- to long-term alternatives to managing the rust, we conducted 2 participatory workshops and 18 interviews with individuals to elicit stakeholders’ key concerns and convert them into 5 objectives (minimize management cost, minimize economic cost to industry, minimize effects on natural ecosystems and landscape amenities, and minimize environmental effects associated with use of fungicide) and to identify the 5 management alternatives (full eradication, partial eradication, slow spread, live with it [i.e., major effort invested in mitigation of effects], and do nothing). We also developed decision trees to graphically represent the essence of the decision by displaying the relations between uncertainties and decision points. In the short term or before local expansion of myrtle rust, the do-nothing alternative was not preferred, but an eradication alternative was only recommended if the probability of eradication exceeded about 40%. After the expansion of myrtle rust, the slow-the-spread alternative was preferred regardless of which of the short-term management alternatives was selected at an earlier stage. The participatory SDM approach effectively resulted in informed and transparent response plans that incorporated multiple objectives in decision-making processes under high uncertainty.

Recently, alternatives to both the structure and content of ‘orthodox’ just war theory have been proposed by Jeff McMahan and David Rodin. In this paper, I draw on this debate to show that key ideas in just war theory can be disputed in both of these respects. More broadly, it is unclear how we should assess the debate between differing conceptions of individual principles (such as just cause and proportionality) and the competing wider theories in which they might be situated. I employ the idea of reflective equilibrium, taken from John Rawls, to show how these conflicting viewpoints might be understood and assessed. I argue, then, that contemporary just war theory faces both important questions of substance, and a set of difficult meta-theoretical issues concerning the grounds on which competing just war theories can be assessed. Futhermore, I contend, this should influence the character of – and our expectations for – real-world just war institutions.

The potential harms associated with global climate change demand an urgent response. But at the same time, the nature and extent of both the problem and our proper response to it are continually contested, within the academic community and wider society. What should be the ethical import of this disagreement? In this paper I set out John Rawls' theory of reasonable disagreement as a way of analysing such contestation. On Rawls' account, reasonable disagreement is founded in diversity rather than straightforward error. I argue that many aspects of the scientific and ethical debate on climate change can be usefully viewed from within such a perspective. This raises, I suggest, serious problems for deciding what the human response to global warming must be. Lastly, I survey two responses which might be thought to cope with such pervasive disagreement. Neither, however, is clearly effective. In my conclusion I suggest that reasonable disagreement might be tackled best in a model of deliberative democracy. Such a model, however, does not generate easy answers to the problems of climate change.

As some thinkers have sought in the concept of global civil society an ethically driven site of deliberation and even resistance, so others have criticized global civil society for its lack of legitimacy and representativeness. This article attempts to answer these criticisms – at least in part – by invoking a moral commitment to the value of justification. I argue that the idea of justification, when examined, offers us a particular understanding of legitimacy which would be attainable for global civil society actors. The article begins by setting out the case for concern about the legitimacy of global civil society. I then outline a certain understanding of justification, showing how a commitment to this conception provides both a response to critics of global civil society and an ethical baseline for humane actors within global civil society. I move on to trace the significance of the moral relevance of justification for actors' strategies. Lastly, however, I highlight the difficulty of justification i...

Electronic health record (EHR) implementation has dramatically impacted all facets of radiology workflow. Many departments find themselves unprepared for the multiple issues that surface following EHR deployment and the ongoing need for workflow optimization. This paper reviews the structure and processes utilized by the team, developed at the University of Colorado Hospital to evaluate, prioritize, and implement requests for workflow repairs and improvements within the EHR. The evolution of this team as the academic hospital formed a health system with two community hospital sites is also described. This structure may serve as a useful template for others considering EHR deployment or struggling to manage radiology workflow within an existing EHR environment.

The removal of arsenic bearing minerals from concentrates is becoming more important as environmental laws become ever stricter with regard to smelter emissions. The onus is shifting to concentrate producers to remove these minerals from their product, with penalties applying to materials containing greater than background amounts. The Rosebery mine, located on the West Coast of Tasmania, is a poly-metallic mine producing a gold dore and concentrates of copper, lead and zinc sulphide through sequential flotation. The zinc concentrate is the major product in terms of both concentrate volume and cash income. Lead concentrate is the secondary earner; copper concentrate and gold dore are only minor products. Copper concentrates from this orebody have reported arsenic concentrations as high as 8000 ppm, well above the 5000 ppm limit set by some importers. The only method currently available to control the concentration of arsenic in copper concentrates is to control the amount of arsenic in the feed through an ore blending regime prior to crushing. This has however proved to be an unreliable method of controlling arsenic concentrations below the target, so this work seeks to find a metallurgical solution to controlling arsenic levels. A mineralogical examination undertaken to identify the mineralogical form of the arsenic bearing minerals indicated that the majority of arsenic entered the mill as arsenopyrite (FeAsS), but tennantite (Cu12As4S13) carried most of the arsenic through to the copper concentrate. A plant survey was undertaken to determine the baseline flotation conditions within the copper circuit. Results indicated that the majority of arsenopyrite was depressed in the rougher circuit, with depression of tennantite in the cleaners, mainly through depression of middling particles. Tennantite contains 51.6% copper and the mineralogical study detected the presence of freibergite (Ag12As4S13). Arsenic reductions from this copper concentrate will also results in the loss of copper and silver. From a literature survey, several means of reducing arsenic concentrations were identified. These include magnetic separation, roasting, regrinding to improve the liberation of arsenic bearing minerals from non-arsenic bearing minerals, chemical depression using lime, cyanide or sulphides or pulp potential controlled flotation. The Rosebery site is located adjacent to environmentally sensitive temperate rainforest, so arsenic removal options had to focus on environmentally neutral methods that will not harm local flora and fauna. Roasting has proven to cause damage to the environment, in particular the Queenstown, Tasmania, area, so was not considered. In addition, with copper concentrates being only a minor product, a flotation solution was sought to minimise capital expenditure and flowsheet changes. Potential flotation tests to reduce the arsenic content was initially investigated, along a series of tests to investigate the effects of regrind, pH and froth depth as well as the additions of cyanide and peroxide. It was found that regrinding had the potential to improve the liberation of the arsenic bearing minerals. Samples of fresh rougher concentrate were ground to produce P80’s of 10, 20 and 30 µms. Flotation tests determined that a P80 of 10 µms produced the greatest selectivity between copper and arsenic, but at a reduced copper recovery. An economic evaluation undertaken on the products of the regrind tests indicated that arsenic penalties were quite low relative to income, and that income from silver exceeds that from copper. Regrinding to 10 µm improved copper/arsenic selectivity, but the reduction in silver recovery dramatically reduced total cash returns. A review of the flotation testwork results has determined that there is a relationship between the copper/arsenic ratio of the copper rougher concentrate and the arsenic content of the final copper concentrate. This will provide an indication of when steps to reduce final arsenic concentration need to be used, while reducing silver losses from overgrinding.

A demand for public justification characterises many contemporary arguments for liberal principles. Nagel notes, ‘the task of discovering the conditions of legitimacy is traditionally conceived as ...

A novel area detector has been designed for material science SR studies, capable of simultaneously collecting the diffraction data in two angular regimes. The detector for collecting wide-angle X-ray scattering (WAXS) data consists of four taper-coupled CCDs arranged as a 2 x 2 mosaic with a central aperture about 40 mm in diameter, so permitting the inclusion of a distant on-axis CCD detector for small-angle X-ray scattering (SAXS). The distance of the SAXS detector from the sample can be varied over the range of 0.27m to about 2m. The overall aperture of WAXS detector is approximately 200 x 200mm2 allowing the measurement of the diffraction patterns from 5o to 45o with an average angular resolution of 0.05o. The parallax error for large angles is substantially reduced as the individual WAXS CCDs are tilted towards the specimen location. both WAXS and SAXS diffraction data are simultaneously collected at 30 MB/s data rate, which is equivalent to 6 complete frames per second. Each pixel value is digitised using low- and high gain Analogue-to-Digital Converters (ADCs) which effectively increase the detector's overall dynamic range. The detector will be used in the study of a whole range of time-dependent phenomena, most importantly reaction kinetics, materials processing and real-time deformation studies. This paper discusses the unusual geometry fo the system, how it relates to design optimisation and the techniques for recovering combined SAXS/WAXS patters.

Many environmental and risk management decisions are made jointly by technical experts and members of the public. Frequently, their task is to select from among management alternatives whose outcomes are subject to varying degrees of uncertainty. Although it is recognized that how this uncertainty is interpreted can significantly affect decision-making processes and choices, little research has examined similarities and differences between expert and public understandings of uncertainty. We present results from a web-based survey that directly compares expert and lay interpretations and understandings of different expressions of uncertainty in the context of evaluating the consequences of proposed environmental management actions. Participants responded to two hypothetical but realistic scenarios involving trade-offs between environmental and other objectives and were asked a series of questions about their comprehension of the uncertainty information, their preferred choice among the alternatives, and the associated difficulty and amount of effort. Results demonstrate that experts and laypersons tend to use presentations of numerical ranges and evaluative labels differently; interestingly, the observed differences between the two groups were not explained by differences in numeracy or concerns for the predicted environmental losses. These findings question many of the usual presumptions about how uncertainty should be presented as part of deliberative risk- and environmental-management processes.

In managing invasions and colonizations of non-native species, eradication or control efforts must proceed quickly. There are 2 challenges in taking such quick action. First, managers frequently have to choose among complex and often competing environmental, social, and economic objectives. Second, the effects are highly uncertain. We applied participatory structured decision making (SDM) to develop a response plan for the recent invasion of non-native myrtle rust (Uredo rangelii) in Australia. Structured decision making breaks a complex decision process into 5 steps: identify problems (i.e., decisions to be made), formulate objectives, develop management alternatives, estimate consequences of implementing those alternatives, and select preferred alternatives by evaluating trade-offs among alternatives. To determine the preferred mid- to long-term alternatives to managing the rust, we conducted 2 participatory workshops and 18 interviews with individuals to elicit stakeholders' key concerns and convert them into 5 objectives (minimize management cost, minimize economic cost to industry, minimize effects on natural ecosystems and landscape amenities, and minimize environmental effects associated with use of fungicide) and to identify the 5 management alternatives (full eradication, partial eradication, slow spread, live with it [i.e., major effort invested in mitigation of effects], and do nothing). We also developed decision trees to graphically represent the essence of the decision by displaying the relations between uncertainties and decision points. In the short term or before local expansion of myrtle rust, the do-nothing alternative was not preferred, but an eradication alternative was only recommended if the probability of eradication exceeded about 40%. After the expansion of myrtle rust, the slow-the-spread alternative was preferred regardless of which of the short-term management alternatives was selected at an earlier stage. The participatory SDM approach effectively resulted in informed and transparent response plans that incorporated multiple objectives in decision-making processes under high uncertainty.

Surgeons increasingly encounter patients on clopidogrel therapy who are preparing to undergo surgery. The goal of this study was to examine the change in platelet function after the common clinical scenario of discontinuing chronic clopidogrel therapy in those patients preparing to undergo an elective surgery, and the time course of platelet function recovery after clopidogrel discontinuation. Patients on clopidogrel therapy scheduled for an elective surgical procedure had their platelet function tested using a VerifyNow P2Y12 device (Accumetrics, San Diego, CA). Platelet inhibition was evaluated at baseline before clopidogrel discontinuation, and subsequently studied every other day in the week before their scheduled procedure. Mean platelet inhibition was 32.1 per cent on Day 0 (before clopidogrel discontinuation), decreasing to 3.7 per cent on Day 4. Platelet inhibition decreased significantly after discontinuation of clopidogrel in a time-dependent manner (P = 0.011), although a considerable interindividual variability of P2Y12 reaction units values was observed over the study period. Patients on concomitant proton pump inhibitors and clopidogrel demonstrated a decreased effect of clopidogrel. In conclusion, individual platelet function monitoring may assist the surgeon in perioperative decision-making in patients receiving clopidogrel therapy preparing to undergo elective surgery.

Progress on recovery plans to conserve endangered species is often blocked due to the lack of an effective framework that technical experts and other knowledgeable stakeholders can use to examine areas of agreement or disagreement about the anticipated effects of management actions. Multi-party, multi-interest resource management deliberations, although increasingly common, are difficult in the context of recovery planning due to the range of potentially affected environmental, economic, and social concerns. These deliberations are further complicated by frequent disagreements among technical experts about how to identify and address various sources of biological uncertainty. We describe the development of a decision-aiding framework as part of an inter-agency plan to assist recovery of endangered Gulf of Maine Atlantic salmon (Salmo salar), using a structured decision making approach that encouraged constructive deliberations based on rigorous analysis. Results are summarized in terms of developing an explicit set of management objectives, clarifying and prioritizing hypotheses concerning barriers to recovery, comparing alternative management initiatives in light of biological uncertainty, and incorporating resource constraints to generate preferred sets of actions. Overall, the use of a structured approach to making recovery decisions improved inter-agency cooperation and facilitated dialogue, understanding, and agreement among participating experts. It also helped to create a defensible basis for further internal discussions as well as for communicating with external stakeholders, including resource users and political decision makers.

Endangered species protection is a significant risk management concern throughout North America. An extensive conceptual literature emphasizes the role to be played by precautionary approaches. Risk managers, typically working in concert with concerned stakeholders, frequently cite the concept as key to their efforts to prevent extinctions. Little has been done, however, to evaluate the multidimensional impacts of precautionary frameworks or to assist in the examination of competing precautionary risk management options as part of an applied risk management decision framework. In this article we describe how decision-aiding techniques can assist in the creation and analysis of alternative precautionary strategies, using the example of a multistakeholder committee charged with protection of endangered Cultus Lake salmon on the Canadian west coast. Although managers were required to adopt a precautionary approach, little attention had been given to how quantitative analyses could be used to help define the concept or to how a precautionary approach might be implemented in the face of difficult economic, social, and biological tradeoffs. We briefly review key steps in a structured decision-making (SDM) process and discuss how this approach was implemented to help bound the management problem, define objectives and performance measures, develop management alternatives, and evaluate their consequences. We highlight the role of strategy tables, employed to help participants identify, alternative management options. We close by noting areas of agreement and disagreement among participants and discuss the implications of decision-focused processes for other precautionary resource management efforts.

The design and development of an area CCD-based X-ray detector system, using the first CCD imagers specially designed for macromolecular crystallography, is presented. The system is intended to produce the highest quality data for physically small crystals at synchrotron sources through the use of large CCDs--that is approaching wafer scale. This work is part of a large research and development program for advanced X-ray sensor technology, funded by industry and the Particle Physics and Astronomy Research Council in the UK. The detector has been optimized by increasing its efficiency at low X-ray energies for conventional laboratory sources, and offers fast readout and high dynamic range needed for efficient measurements at synchrotron sources. The detector consists of CCDs optically coupled to a X-ray sensitive phosphor via skewed fiber-optic studs. The individual three- sides buttable CCD consists of 2048 X 1536 27 micrometers square pixels (55.3 X 41.5 mm). The pixel size has been optimized to match diffraction spot profiling needs and the high dynamic range required for such applications. The multiple amplifier outputs possess switched responsivity to maximize the trade-off between signal handling capabilities and linearity. The readout noise is 5 electrons rms at a 1 MHz pixel rate at the high responsivity setting. A prototype detector system comprising two close-butted cooled CCDs is being developed. This system employs a high-efficiency scintillator with very low point spread function, skewed optical-fiber studs (instead of the more usual demagnifying tapers) to maximize the system's detective quantum efficiency and minimize optical distortions. Full system specifications and a novel crystallographic data processing are presented.

Very sophisticated electronic equipment is now available in medical fields to help in the diagnosis and treatment of disease and illness. People now readily accept the use of body scanners, kidney dialysis machines, electrocardiographs and heart pacemakers without always knowing that in each are electronic sensors and complex circuitry which are essential for the equipment to function. The applications mentioned in this chapter will be far more mundane but at least the mixture will be unusual!

Do you know how shirt buttons, or for that matter any buttons used as fasteners for garments, are made? I had always assumed that they were sawn off discs from an extruded plastic bar with the holes as tubes already in the bar. But no; first a flat sheet of resinous material is cast, and blanks, almost the same diameter as the final buttons, are punched out from the sheet before it has cured. Then the blanks are drilled and the surfaces machined. Finally they are polished before dispatch. The main reason for the process is so that subtle layering can be built in during the initial resin casting to enhance the resulting reflective properties.

Clothing and garments, which featured mainly in the last chapter, provide suitable protection against the elements for humans but most manufactured items, especially the fragile and delicate, require protective transit packaging to make sure they reach their destination intact. One of the most common types of such packaging is corrugated cardboard which is usually made from reprocessed paper. Double-sided board consists of two outer sheets spaced apart by an undulating sheet which is glued alternately to the insides of the two outer sheets. Because of its inherent strength, which is produced by the closed box construction, it is remarkably effective. A single-sided board is also made which is less rigid and conforms more closely to the object to be packed.

Quality and quantity inspection are essential in any industry but in the food industry they are a vital part of the manufacturing process. Samples of the product are taken away regularly for checking in a laboratory and continuous inspection of the product on the line is also necessary. Modern electronic scales can be used rapidly to check-weigh every item produced so that a guaranteed, minimum weight is delivered to the customer. Measurements of size and shape can be made, as was described for potatoes in chapter 2 (page 13), and items can be counted electronically. There are many pieces of electronic equipment available for carrying out quantity measurements.

In the early 1970s there were few electronics circuits in use on the average farm, except perhaps for electric fences. The idea of introducing anything so unreliable and delicate into such a tough environment would have been considered ridiculous. People were suspicious of new fangled gadgets and the days of delicate glass valves with high internal voltages were only just receding. Electronically controlled fences were probably accepted because they had to generate high voltages to give an electric shock and, as they were not shaken by being mounted on moving machinery but left quietly alone in the corner of fields, they were reliable. It was the coming of good-quality printed circuit boards, much lower operating voltages and cheap transistors which enabled rugged, low-cost electronic sensors to be produced.

This chapter is meant to add a few details which were deliberately left out in the earlier chapters as such facts might have caused a distraction from the application being described. Even so it is not intended to explain the operation of semiconductors, such as transistors, using Solid State Physics but only to consider them in their simplest form as current controlled switches and amplifiers. For a more rigorous description, some references to other suitable books are provided in Further Reading (page 143) at the end of the book. The information given is therefore only intended to assist the reader to understand how the sensors and circuits describe previously operate and is not meant to be a comprehensive guide to all electronic sensors.