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101.
This is an extension of an earlier paper by the second author. In the previous work, an algorithm was derived for the moments of an homogeneous equation with noise similar to the white noise, but has small, finite correlation time. In the present work this algorithm is extended for an inhomogeneous equation with the same characteristics. Previous notation has been kept throughout the paper. 相似文献
102.
Martin A. Pomerantz 《Journal of The Franklin Institute》1946,241(6):415-433
The secondary electron emission from alkaline-earth oxide-coated cathodes has been investigated under both continuous and pulsed bombardment. Various factors affecting the yield, such as dependence upon primary voltage, collecting voltage, temperature, time, and angle of incidence, are noted, and the present state of the theory is discussed.Experiments have been performed with three types of apparatus. Yield vs. Energy data reveal values of δ of 4–7 at room temperature, with a more or less flat maximum at approximately 1,000 volts primary energy.The yield increases with temperature in an exponential manner, and plots of log Δδ (i.e. δK° ? δ300°K) vs. 1/T give straight lines. Values of Q1 between 0.9 – 1.5 eV. are generally indicated, and from extrapolation of these curves, yields exceeding 100 at 850° C. are deduced. The secondary emission depends upon the degree of activation, and increases with enhancement of the thermionic emission characteristics. Short-time effects such as growth or decay of secondary current after the onset of primary bombardment or persistence after the cessation of bombardment have not been observed, and values of yield obtained by pulsed methods are in accord with those obtained under D.C. conditions. Tail phenomena reported by J. B. Johnson and interpreted as “enhanced thermionic emission” from oxidecoated cathodes become manifest only under experimental conditions characterized by certain space-charge effects, and have been effectively simulated by bombarding a tantalum target adjacent to an electron-emitting tungsten filament. Various measurements of the energy distribution of secondary electrons as a function of primary voltage and temperature have been obtained. It was observed that the average energy of the secondary electrons decreases with temperature at a rate which more than compensates for the increase in the number of secondaries emitted per incident primary. The mechanism of the observed dependence of yield upon temperature is not well understood. Various alternative explanations are discussed and, in the light of the present state of our knowledge, regarded as untenable. 相似文献
103.
Martin K. Klämpfl Philipp B. Philippen Babett H. Lobinger 《Journal of sports sciences》2015,33(7):655-664
The yips is considered a task-specific movement disorder. Its estimated prevalence, however, is high compared to similar neurological movement disorders, possibly resulting from previous studies’ restriction of samples based on skill level, and self-report bias. Alternatively, this high prevalence might be an indication of additional aetiologies, for example the influence of previously played racket sports. We estimated the prevalence of the putting yips across the skill range, using self-reports in one study and a screening test in a second study. We explored if previously played sports matter for the development of the yips. In study 1, yips prevalence (N = 1,306) and golfers’ sports biographies (n = 264) were examined via two online surveys, in which golfers indicated if they were yips-affected. In study 2, golfers (N = 186) putted in a standardised putting test while kinematic and performance measures were recorded. Prevalence was estimated via a kinematic threshold. Sports biographies (n = 119) were obtained via an online survey. Prevalence of currently yips-affected golfers was 22.4% in study 1 and 16.7% in study 2. In both studies, more yips-affected than unaffected golfers had experience in playing racket sports. Yips prevalence remained higher than previously estimated prevalence of other movement disorders but decreased when the whole skill range including professionals and novices was considered. Future studies should use the kinematic screening test instead of self-reports to detect the yips and further investigate the influence of previously played racket sports. 相似文献
104.
Thomas G. Martin Rachel W. Pata Johanna D’Addario Lauren Yuknis Rebecca Kingston Richard Feinn 《Journal of sports sciences》2015,33(19):1988-1997
This study investigated whether haematological markers differ between young and masters marathon participants, running at similar performance levels. Nine young (31.89 ± 4.96 years) and eight masters (63.13 ± 4.61 years) runners participated. At five time points (pre-race through 54 h post-race), a complete blood cell count, basic metabolic panel and creatine kinase (CK) isoenzyme panel were assessed. Race performance was standardised using the World Masters Association Age Grading Performance Tables. Total CK levels were elevated for all participants at all time points post-race (P < 0.001). The CK-isoenzyme MB% was elevated across groups at 6, 30 and 54 h post-race (P < 0.01, P < 0.01 and P < 0.05), with masters runners having a higher CK-MB% at 30 and 54 h (P < 0.05, P < 0.05). Total white blood cell and neutrophil counts were elevated through 6 h post-race (P < 0.001), with higher levels found in younger runners (P < 0.001). When considering all blood work, masters runners had a higher number of abnormal values at 6, 30 and 54 h post-race (P < 0.05, P < 0.01 and P < 0.05). In conclusion, masters runners demonstrated sustained CK-MB elevation, which may suggest greater cardiac stress. However, future studies using additional cardiac markers should be completed to confirm these findings. In addition, masters runners showed an increased number of laboratory values outside normal range, indicating the body’s reduced capacity to respond to marathon running. 相似文献
105.
Martin Johnes 《国际体育史杂志》2015,32(15):1784-1798
Archives and the documents within them are at the heart of the practice of history and the occupational culture of historians. A majority of historical work has been characterized and defined by research in archives of varying kinds. Yet, the material within archives is both partial and political and using it is never straightforward. For historians of sport, the material available in archives can be especially limited but, with some careful reading between the lines, there is still much to learn from and interpret within traditional archives. This paper explores the different kinds of archives and archival material that historians of sport have used and the uses they have been and can be put to. Archives, however, are not static entities and the paper also discusses the impact and implication of digitization processes and programmes to popularize and legitimize traditional archives. Although sport has been seen as one of the ways of diversifying the content and audience of archives, the paper argues that the practical and interpretative challenges historians of sport face in archives are no different to those faced by other historians. 相似文献
106.
Big and open linked data analytics ecosystem: Theoretical background and essential elements 总被引:1,自引:0,他引:1
Big and open linked data are often mentioned together because storing, processing, and publishing large amounts of these data play an increasingly important role in today's society. However, although this topic is described from the political, economic, and social points of view, a technical dimension, which is represented by big data analytics, is insufficient. The aim of this review article was to provide a theoretical background of big and open linked data analytics ecosystem and its essential elements. First, the key terms were introduced including related dimensions. Then, the key lifecycle phases were defined and involved stakeholders were identified. Finally, a conceptual framework was proposed. In contrast to previous research, the new ecosystem is formed by interactions of stakeholders in the following dimensions and their sub-dimensions: transparency, engagement, legal, technical, social, and economic. These relationships are characterized by the most important requisites and public policy choices affecting the data analytics ecosystem together with the key phases and activities of the data analytics lifecycle. The findings should contribute to relevant initiatives, strategies, and policies and their effective implementation. 相似文献
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The need to address the substantial inequities that exist between Indigenous and non-Indigenous Australians in higher education is widely recognised. Those factors that affect the performance of Indigenous students in tertiary education have been reasonably well documented across different institutions, disciplines, and programme levels but there has, to date, been less consideration of the processes by which Indigenous students either persist or desist in higher education. This paper aims to present a conceptual understanding of academic persistence that can inform the delivery of tailored academic support interventions to Indigenous students who are at high risk of leaving higher education. 相似文献