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961.
Historians of science, inasmuch as they are concerned with knowledges and practices rather than institutions, have tended of late to focus on case studies of common processes such as experiment and publication. In so doing, they tend to treat science as a single category, with various local instantiations. Or, alternatively, they relate cases to their specific local contexts. In neither approach do the cases or their contexts build easily into broader histories, reconstructing changing knowledge practices across time and space. This essay argues that by systematically deconstructing the practices of science and technology and medicine (STM) into common, recurrent elements, we can gain usefully "configurational" views, not just of particular cases and contexts but of synchronic variety and diachronic changes, both short term and long. To this end, we can begin with the customary actors' disciplines of early modern knowledge (natural philosophy, natural history, mixed mathematics, and experimental philosophy), which can be understood as elemental "ways of knowing and working," variously combined and disputed. I argue that these same working knowledges, together with a later mode-synthetic experimentation and systematic invention-may also serve for the analysis of STM from the late eighteenth century to the present. The old divisions continued explicitly and importantly after circa 1800, but they were also "built into" an array of new sciences. This historiographic analysis can help clarify a number of common problems: about the multiplicity of the sciences, the importance of various styles in science, and the relations between science and technology and medicine. It suggests new readings of major changes in STM, including the first and second scientific revolutions and the transformations of biomedicine from the later twentieth century. It offers ways of recasting both microhistories and macrohistories, so reducing the apparent distance between them. And it may thus facilitate both more constructive uses of case studies and more innovative and acceptable longer histories.  相似文献   
962.
Thrombotic risk factors may contribute to premature coronary artery disease (CAD), in addition to the conventional risk factors. There is paucity of data on studies evaluating the role of thrombotic factors in premature CAD in Indian patients. Thus a case–control study was performed to evaluate the role of thrombotic and atherogenic factors in young patients with angiographically proven CAD who are on treatment with statins and anti-platelet drugs. 152 patients (≤55 years) with angiographically proven CAD and 102 asymptomatic controls were recruited. Clinical and biochemical data were obtained in both groups. Blood levels of thrombotic factors-fibrinogen, antithrombin-III, tissue-plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), von-Willebrand factor (v-WF), lipoprotein(a) [Lp(a)] and homocysteine were analyzed. Patients had high levels of conventional CAD risk factors (diabetes mellitus, smoking, hypertension, dyslipidemia and positive family history) compared to controls. Logistic regression analysis revealed that low antithrombin-III (odds ratio/OR 11.2; 95 % confidence interval/CI 2.29–54.01), high fibrinogen (OR 6.04; 95 % CI 1.09–33.21) and high Lp(a) (OR 4.54; 95 % CI 0.92–22.56), as important, independent risk factors in patients. PAI-1(OR 0.15; 95 % CI 0.03–0.69) levels were significantly lower in patients. But other thrombotic risk factors studied (t-PA, v-WF and homocysteine) were comparable among patients and controls. The treatment using statins and anti-platelet drugs might be contributing to the control of some of the thrombotic risk factors. The strategies aiming at lowering the levels of thrombotic risk factors along with conventional risk factors may be useful in primary and secondary prevention of CAD.  相似文献   
963.
Traditionally, it has been assumed that during middle-distance running oxygen uptake (VO2) reaches its maximal value (VO2max) providing the event is of a sufficient duration; however, this assumption is largely based on observations in individuals with a relatively low VO2max. The aim of this study was to determine whether VO2max is related to the VO2 attained (i.e. VO2peak) during middle-distance running on a treadmill. Fifteen well-trained male runners (age 23.3 +/- 3.8 years, height 1.80 +/- 0.10 m, body mass 76.9 +/- 10.6 kg) volunteered to participate in the study. The participants undertook two 800-m trials to examine the reproducibility of the VO2 response. These two trials, together with a progressive test to determine VO2max, were completed in a randomized order. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest VO2 during the progressive test (i.e. VO2max) was compared with the highest VO2 during the 800-m trials (i.e. VO2peak) to examine the relationship between VO2max and the VO2 attained in the 800-m trials. For the 15 runners, VO2max was 58.9 +/- 7.1 ml x kg(-1) x min(-1). Two groups were formed using a median split based on VO2max. For the high and low VO2max groups, VO2max was 65.7 +/- 3.0 and 52.4 +/- 1.8 ml x kg(-1) x min(-1) respectively. The limits of agreement (95%) for test-retest reproducibility for the VO2 attained during the 800-m trials were +/- 3.5 ml x kg(-1) x min(-1) for a VO2peak of 50.6 ml x kg(-1) x min(-1) (the mean VO2peak for the low VO2max group) and +/- 2.3 ml x kg(-1) x min(-1) for a VO2peak of 59.0 ml x kg(-1) x min(-1) (the mean VO2peak for the high VO2max group), with a bias in VO2peak between the 800-m runs (i.e. the mean difference) of 1.2 ml x kg(-1) x min(-1). The VO2peak for the 800-m runs was 54.8 +/- 4.9 ml x kg(-1) x min(-1) for all 15 runners. For the high and low VO2max groups, VO2peak was 59.0 +/- 3.3 ml x kg(-1) x min(-1) (i.e. 90% VO2max) and 50.6 +/- 2.0 ml x kg(-1) x min(-1) (i.e. 97% VO2max) respectively. The negative relationship (-0.77) between VO2max and % VO2max attained for all 15 runners was significant (P = 0.001). These results demonstrate that (i) reproducibility is good and (ii) that VO2max is related to the %VO2max achieved, with participants with a higher VO2max achieving a lower %VO2max in an 800-m trial on a treadmill.  相似文献   
964.
965.
It is frequently assumed that undernutrition in young children leads to poor development through reduced activity. 3 groups of 26 1-year-old stunted children were studied: nutritional supplementation, supplementation with psychosocial stimulation, and controls. 26 nonstunted comparison children were also studied. Activity levels were measured by extensive observations in the homes, and development using 4 subscales of the Griffith's Mental Development Scales. Initially, stunted children were less active than nonstunted ones ( p < .01), but after 6 months they caught up regardless of treatment. The mental ages of the stunted children were lower than those of the nonstunted children initially, and improved with either treatment. Initially, activity levels made a significant contribution to the variance in the locomotor subscale only, but not 6 months later. Activity did not predict change in development over 6 or 12 months, nor did change in activity over 6 months predict change in development over 12 months.  相似文献   
966.
967.
This article considers the tensions and struggles that exist between men and women and between women and women in the academic workplace. The research reported here is a small‐scale case study of 22 academic women from two generations who were interviewed about their career experiences. The theoretical framework is materialist feminism and draws on Ulrich Beck’s model of the ‘individualized individual’ to evaluate its usefulness to researchers for understanding the attitudes and actions of social actors in contemporary society. The article, firstly, examines the ways in which power differentials emerged for the younger female academics through a combination of their age and gender. It then discusses intra‐gender tensions between women in the academy. It is argued that for Beck’s model of an ‘individualized individual’ to be useful in understanding the position of women in the second modernity then a much more complex and nuanced interpretation of power and power struggles is needed than the one he provides. A further key point raised by the article is that feminists need to be more prepared to recognize and engage with power struggles and tensions that exist between women (and feminists) in the academy.  相似文献   
968.
水位变化作为湖泊水文过程和水量平衡的动态反映,是湖泊生态环境的重要影响因素。全球最大的淡水湖——贝加尔湖,在自然变化与人为活动的双重影响下,过去100多年水位表现出较大的年内、年际和多年变化。贝加尔湖水位变化与入湖径流量变化密切相关,与贝加尔湖最大支流色楞格河的径流量变化较为一致。气候变暖带来的气温上升和降水减少使得入湖径流量减少,贝加尔湖水位下降。人类活动对贝加尔湖水位变化影响表现在两个方面:一方面,全球变暖条件下耕地面积扩张和灌溉用水增加导致贝加尔湖流域用水增加,使得入湖径流量减少,贝加尔湖水位下降;另一方面,1958年伊尔库茨克水电站投入运营之后,贝加尔湖水位变化受到了安加拉河水位顶托的影响。在下游水电站人为调控影响下,贝加尔湖年平均水位升高,年内水位波动幅度增加,年最低和最高水位出现日期推迟。地处全球气候与环境变化敏感区的贝加尔湖,其水位变化对湖泊及周边生态环境影响显著。因此,探究在全球变化背景下贝加尔湖的水位变化及影响因素对保护当地生态环境具有重要意义。  相似文献   
969.
A number of countries are running role model recruitment drives under the assumption that like is good for like: ethnic minority teachers should teach ethnic minority children, women should teach girls, and so on. The empirical basis for this would appear to be case study and personal reflection. This article will examine quantitative data to test the hypothesis that male teachers produce more positive attitudes amongst boys and female teachers amongst girls. Using data from the Performance Indicators in Primary Schools (PIPS) Project, information from 413 separate classes for 11 year‐olds (in England) was examined. One hundred and thirteen were taught by males and 300 by females. All the pupils completed questionnaires that were designed to measure attitude to school, reading, mathematics and science. In addition, background data on those pupils were collected, including cognitive measures, attainment scores, ability measures and home background measures. The data were examined to look at attitudes using multilevel models controlling for background factors. The analysis concentrated on interaction effects between the gender of the teacher and the gender of the pupil and the results gave little support for those who advocate recruitment drives with role models in mind.  相似文献   
970.
There has been considerable media coverage highlighting the lack of gender diversity in Silicon Valley, stressing the relatively low participation of women in the high-tech economy. Austin offers a unique case for testing whether similar gender issues characterized other high-tech regions because the city has historically benefited from the expansion of Silicon Valley’s large high-tech firms since the 1980s. The gender-biased business practices identified in Silicon Valley firms may have been transferred to their branch plants in Austin. Our analysis shows women’s losses in middle-skill occupation employment shares were concentrated in the low-tech industry and were partially offset by job share gains in high-skill occupations in the same sector between 1980 and 2015. Men’s losses in middle-skill occupation job share were also mainly concentrated in the low-tech sector but were partially offset by employment share gains in high-skill occupations only in the high-tech industry during this period. Women made large gains in relative real median wages only in high-skill occupations in the high-tech industry while their relative real median wages in other skill occupations and in the low-tech industry stagnated around zero during this period. Men’s gains in relative median wages were also concentrated only in the high-tech industry but were less than half of women’s and were negative (between ?10 and ?21 percent) in other occupations in the high-tech industry and across all occupations in the low-tech industry. As noted in previous studies, the impact of job polarization is not well understood across sectors and gender. This study finds the high-tech industry in Austin has had unintended consequences in terms of job polarization across gender, providing relatively fewer job opportunities in high-skill occupations to women than men but offering much higher gains in relative real median wages to women than men. Males also found relatively more job opportunities in high-skill occupations in the high-tech industry than women but experienced only half of women’s gains in relative median wages in this industry between 1980 and 2015.  相似文献   
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