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In the formative period of London's scientific instrument industry membership of a guild was a necessary step towards owning a business in the City. Through the guilds' formal system of apprenticeship, boys received first-class training in a skilled trade, and learned essential marketing and managerial techniques. By analysing the guilds' records of apprenticeship and subsequent guild life it is possible to determine chains of masters and apprentices by which the knowledge passed from generation to generation. At the same time, dates can be established for the training and subsequent working life of many known makers. The chains of knowledge reveal new and often important masters who were previously unknown because, by chance, their instruments or advertisements have not survived to the present day. Two guilds have been used to illustrate the chains: Broderers' Company and Joiners' Company.  相似文献   
164.
In 1793 Lord Macartney arrived in China as ambassador of King George III. The aims of his embassy were largely directed towards the enlargement of British trade with the far east, and especially with China. The embassy also had a diplomatic and cultural mission, to impress the Chinese with British achievements. They were to do so largely by distributing presents of British manufactures, chief among them being scientific instruments. The Chinese refused the embassy's requests, and clearly regarded the gifts of instruments as merely ingenious toys. This paper describes the role of instruments in the embassy, and contrasts British expectations with Chinese attitudes to scientific instruments. The embassy's failure is shown to reveal fundamental differences in British and Chinese eighteenth-century responses to science, and has wide cultural implications.  相似文献   
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The famous French chemist, Marcelin Berthelot, published his first scientific paper in 1850. However, reference to this paper has been largely ignored in the various accounts of his lasting contributions to chemistry. The probable reason for this is that this paper is concerned with a method of subjecting a liquid to tension, and it is more appropriate to regard it as a paper on physics rather than on chemistry. In the work described in this largely-forgotten paper, written whilst he was still a young research student, Berthelot showed that liquids contained in his ‘Berthelot tube’ could withstand a considerable tension; and he is the first person to have observed cavitation, a phenomenon which has been studied so widely this century. The next mention in the literature of the Berthelot tube method is at the turn of the present century, after which it again seems to have been forgotten until the 1940s; since then there has been considerable progress using the Berthelot tube technique. In this paper the work described in Berthelot's original paper is discussed in some detail, and the subsequent fruitful development of the method is also traced and assessed.  相似文献   
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In 1807 the first life insurance society was established in The Netherlands. In the second half of the century, life insurance societies underwent considerable expansion. During the intervening period, the lines had to be laid along which this new phenomenon was to develop in the future: between 1827 and 1830, the government started discussing the nature of its responsibility in this field and the kind of policy to be developed, and in 1830, a book on the organization of life insurance societies, the calculation of life annuities and widows' fund premiums was published, written by the mathematician Rehuel Lobatto. This book played an important role in the government's discussion. Royal Decrees which prescribed government approval for the establishment of life assurance societies were promulgated in 1830, 1833 and 1840. In 1832, Lobatto became the government's scientific adviser on the assessment of the calculations performed by these societies, and in the same year, he was also appointed adviser to the first life insurance society. From 1832 until his death in 1866 he advised the company on the use of life tables for life as well as for reversionary annuities, and he calculated the premiums based on these life tables. Another decree was promulgated in 1864 prescribing exactly which life tables were to be used. Because Lobatto probably played a part in this decree, he was responsible for a very ‘conservative’ government policy, which was no longer adequate in the second half of the century.  相似文献   
169.
Estrogens are important endocrine regulators of skeletal growth and maintenance in both females and males. Studies have demonstrated that the estrogen receptor (ER)-α is the main mediator of these estrogenic effects in bone. Therefore, estrogen signaling via ERα is a target both for affecting longitudinal bone growth and bone remodeling. However, treatment with estradiol (E2) leads to an increased risk of side effects such as venous thromboembolism and breast cancer. Thus, an improved understanding of the signaling pathways of ERα will be essential in order to find better bone specific treatments with minimal adverse effects for different estrogen-related bone disorders. This review summarizes the recent data regarding the intracellular signaling mechanisms, in vivo, mediated by the ERα activation functions (AFs), AF-1 and AF-2, and the effect on bone, growth plate and other estrogen responsive tissues. In addition, we review the recent cell-specific ERα-deleted mouse models lacking ERα specifically in neuronal cells or growth plate cartilage. The newly characterized signaling pathways of estrogen, described in this review, provide a better understanding of the ERα signaling pathways, which may facilitate the design of new, bone-specific treatment strategies with minimal adverse effects.  相似文献   
170.
Sodium absorption by the distal part of the nephron, i.e., the distal convoluted tubule, the connecting tubule, and the collecting duct, plays a major role in the control of homeostasis by the kidney. In this part of the nephron, sodium transport can either be electroneutral or electrogenic. The study of electrogenic Na+ absorption, which is mediated by the epithelial sodium channel (ENaC), has been the focus of considerable interest because of its implication in sodium, potassium, and acid–base homeostasis. However, recent studies have highlighted the crucial role played by electroneutral NaCl absorption in the regulation of the body content of sodium chloride, which in turn controls extracellular fluid volume and blood pressure. Here, we review the identification and characterization of the NaCl cotransporter (NCC), the molecule accounting for the main part of electroneutral NaCl absorption in the distal nephron, and its regulators. We also discuss recent work describing the identification of a novel “NCC-like” transport system mediated by pendrin and the sodium-driven chloride/bicarbonate exchanger (NDCBE) in the β-intercalated cells of the collecting system.  相似文献   
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