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City dwellers occasionally must seek jobs, dwellings, or particular services or goods. Two very different ways exist by which the individual may conduct such a search. Lacking prior information, the person may elect to visit perceived possible locations until an appropriate one is found. Alternatively, an address may first be ascertained and then visited by finding a path to it. Clearly, there is a substantial difference between these two methods in terms of the amount of spatial movement they require in order to satisfy the searcher's needs. In this paper, this difference is modeled for situations that vary in terms of the density of acceptable end points of the search, as well as in characteristics of the signs of these end points, their patterns, and the level of information with which the searcher may begin.  相似文献   
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This article examines the introduction of blood transfusion into general practice from the end of the First World War to the Second World War. Developments during most of this period were not the result of new discoveries but rather the spread of ideas and the establishment of donor organizations to secure an adequate blood supply. The identification, testing, and organization of potential donors were done in a wide variety of settings that reflected differences in political and cultural experiences. At the end of the 1930s, with war approaching, the resolution of problems with storage of blood and the discovery of new techniques for separating and storing plasma dramatically changed transfusion practice. Thus, the innovations of the Second World War were very much based on the development of broad donor organizations plus the new technical discoveries that had occurred during the interwar period.  相似文献   
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Ohne Zusammenfassung  相似文献   
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A number of recent allegations of scientific misconduct in Germany have led to judicial proceedings. Two examples are analyzed in depth, showing evidence for mutual incompatibilities between the legal system and the scientific system. In particular, it seems doubtful whether basic rules of good scientific practice are adequately and consistently taken into account by the courts when assessing the burden of proof. Strengths and weaknesses of some alternatives to judicial proceedings in such cases are discussed.  相似文献   
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In Roman and Byzantine times, natron glass was traded throughout the known world in the form of chunks. Production centers of such raw glass, active from the 4th to 8th century AD, were identified in Egypt and Syro-Palestine. However, early Roman primary glass units remain unknown from excavation or scientific analysis. The ancient author Pliny described in 70 AD that besides Egyptian and Levantine resources, also raw materials from Italy and the Gallic and Spanish provinces were used in glass making. In this study, the primary provenance of 1st–3rd century AD natron vessel glass is investigated. The use of combined Sr and Nd isotopic analysis allows the distinguishing and characterizing of different sand raw materials used for primary glass production. The isotope data obtained from the glass samples are compared to the signatures of primary glass from known production centers in the eastern Mediterranean and a number of sand samples from the regions described by Pliny the Elder as possible sources of primary glass. Eastern Mediterranean primary glass has a Nile dominated Mediterranean Nd signature (higher than −6.0 ? Nd), while glass with a primary production location in the western Mediterranean or north-western Europe should have a different Nd signature (lower than −7.0 ? Nd). Most Roman glass has a homogeneous 87Sr/86Sr signature close to the modern sea water composition, likely caused by the (intentional) use of shell as glass raw material. In this way, strontium and neodymium isotopes now prove that Pliny's writings were correct: primary glass production was not exclusive to the Levant or Egypt in early Roman days, and factories of raw glass in the Western Roman Empire will have been at play.  相似文献   
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ABSTRACT

There is scepticism about whether a state like Australia can secure its interests and exercise influence on the United Nations Security Council (UNSC). A case study of Australia’s experience as a UNSC member in 2013–2014 shows that it directly influenced UNSC decision-making in a number of ways: first, in the response to the MH17 incident; second, pushing forward UNSC practice through the first-ever resolutions on both ‘small arms and light weapons’ and police in peacekeeping; and third, as chair of three sanctions committees, influencing the decision-making environment towards greater transparency. While Australia did not achieve all its objectives, it made its views well-known. A second case study demonstrates that Australia’s opportunities to influence UNSC decision-making are not limited to stints of membership. Australia was able to achieve many of its foreign policy objectives in East Timor in 1999 through strategically engaging with key UNSC players through an informal diplomatic grouping: the Core Group on East Timor. Both case studies show that Australia’s diplomatic engagement with the UNSC is desirable, necessary and strategic, whether or not it is a current or prospective member.  相似文献   
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