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162.
Considering the uncertainty of material performance, geometric characteristic and analysis method, the analysis of statistical parameters of the resistance of cast ball-and-socket support joints and the reliability analysis are carried out by JC method (improved first-order second-moment method) based on the relevant experimental data. Results show that the resistance partial factor of the joint increases with the increase of the reliability index. The resistance partial factors are suggested corresponding to the reliability index under different load combinations. Moreover, the suggested resistance partial factor is adopted in reliability design, and it is found that the reliability index of the joint is larger than the target reliability index. The optimal load combination is the one in which live load plays an important control role. Finally, based on the suggested resistance partial factors, the reliability analysis of cast ball-and-socket support joints of a project is conducted. 相似文献
163.
Afforestation in China provides carbon sequestration and prevents soil erosion, but its remote impacts on climate in other regions via the coupling of forest energy fluxes with atmospheric circulation are largely unknown. Here, we prescribe inventory-based forest cover change and satellite-observed leaf area index from 1982 to 2011 in a coupled land-atmosphere model to simulate their biophysical climate effects. Both local and global surface air temperatures show a seasonal contrast in response to past vegetation cover expansion over China: a phenomenon we primarily attribute to a variation of seasonality of vegetation greening. A large cooling in spring results in concurrent decreases in geopotential height over China and zonal wind over Mongolia, causing a dipole structure in the upper troposphere over the Arctic. This accounts for ∼58% of simulated spring warming over the Russian Arctic and ∼61% of simulated spring cooling over the Canadian Artic. Our results imply that spring vegetation dynamics in China may affect climate in northern high latitudes. 相似文献
164.
Kelsey H.Collins Graham Z.MacDonald David A.Hart Ruth A.Seerattan Jaqueline L.Rios Raylene A.Reimer Walter Herzog 《运动与健康科学(英文)》2020,9(2):132-139,197
Background:Osteoarthritis is one of the leading causes of pain and disability worldwide,and a large percentage of patients with osteoarthritis are individuals who are also obese.In recent years,a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage(both with and without the superimposition of trauma),which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators.Of note,there is a disparity between whether the dietary challenges commence at weaning,representing a weanling onset,or at skeletal maturity,representing an adult onset of obesity.We wished to evaluate the effect ofthe dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose(HFS) diet to determine whether these factors may result in disparate outcomes,as there is evidence suggesting that these factors result in differential metabolic disturbances.Based on dietary exposure time,we hypothesized that rats fed an HFS diet for 14 weeks from weaning(HFS Weanling) would demonstrate an increase in knee joint damage scores,whereas rats exposed to the HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult) and rats exposed to a standard chow diet(Chow)would not display an increase in knee joint damage scores.Methods:Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning(HFS Weanling) or an HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult).At sacrifice,joints were scored using the modified Mankin Criteria,and serum was analyzed for a defined subset of inflammatory markers(Interleukin-6,leptin,monocyte chemoattractant protein-1,and tumor necrosis factorα).Results:When the HFS Weanling and HFS Adult groups were compared,both groups had a similar percent of body fat,although the HFS Weanling group had a significantly greater body mass than the HFS Adult group.The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group.Although knee joint damage scores were low in all 3 groups,we found,contrary to our hypothesis,that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups.Furthermore,we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.Conclusion:These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group.Interestingly,when assessing various serum proinflammatory markers,no significant differences were detected between the HTS Adult and HFS Weanling groups.Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated,these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced.Moreover,increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet. 相似文献
165.
Pauliina Husu Jaana Suni Kari Tokola Henri Vähä-Ypyä Heli Valkeinen Tomi Mäki-Opas 《Journal of sports sciences》2019,37(16):1840-1848
This cross-sectional study analysed the association of sedentary behaviour (SB) and standing with waist circumference. Finnish adults aged 30-75 years from a sub-sample of population-based Health 2011 Study used a hip-worn tri-axial accelerometer (Hookie AM20, Traxmeet, Ltd, Espoo, Finland) for seven days. Those 1405 participants (57% women) who used accelerometer at least four days, minimum of 10 hours/day, were included. SB and standing were analysed in 6s epochs using validated algorithm. Daily total time, daily number and accumulated time from bouts (30s–5min,30s–10min,30s–15min,30s 30min,>5min,>10min,>15min, >30min) as well as daily number of sit-to-stand transitions were determined. Waist circumference (cm) was measured in standardized way. Participants’ mean age was 52 years (SD 12.2). Mean waist circumference was 97cm (SD 12.3) in men and 87cm (SD 12.7) in women. According to multivariable stepwise linear regression analysis, sit-to-stand transitions [standardised regression coefficient (β)= -0.14, 95%CI -0.20 to -0.09], standing bouts of 30s–5min (β= -0.21, 95%CI -0.26 to -0.15) and number of 30s-30min SB bouts (β=0.12, 95%CI 0.06 to 0.17) were most strongly associated with waist circumference. Besides assessing total SB time, future studies should assess also different bout lengths of SB and sit-to-stand transitions and standing times should be assessed separately. 相似文献
166.
Funding agencies in Canada are attempting to break down the organizational boundaries between disciplines to promote interdisciplinary
research and foster the integration of the social sciences into the health research field. This paper explores the extent
to which biomedical and clinician scientists’ perceptions of social science research operate as a cultural boundary to the
inclusion of social scientists into this field. Results indicated that cultural boundaries may impede social scientists’ entry
into the health research field through three modalities: (1) biomedical and clinician scientists’ unfavourable and ambivalent
posture towards social science research; (2) their opposition to a resource increase for the social sciences; and (3) clinician
scientists procedural assessment criteria for social science. The paper also discusses the merits and limitations of Tom Gieryn’s
concept of boundary-work for studying social dynamics within the field of science.
相似文献
Brian D. HodgesEmail: |
167.
Rethinking Polanyi’s Concept of Tacit Knowledge: From Personal Knowing to Imagined Institutions 总被引:1,自引:0,他引:1
Half a century after Michael Polanyi conceptualised ‘the tacit component’ in personal knowing, management studies has reinvented
‘tacit knowledge’—albeit in ways that squander the advantages of Polanyi’s insights and ignore his faith in ‘spiritual reality’.
While tacit knowing challenged the absurdities of sheer objectivity, expressed in a ‘perfect language’, it fused rational knowing, based on personal experience, with mystical speculation about an un-experienced ‘external reality’. Faith alone saved Polanyi’s model from solipsism. But Ernst von Glasersfeld’s
radical constructivism provides scope to rethink personal tacit knowing with regard to ‘other people’ and the intersubjectively
viable construction of ‘experiential reality’. By separating tacit knowing from Polanyi’s metaphysical realism and drawing
on Benedict Anderson’s concept of ‘imagined communities’, it is possible to conceptualise ‘imagined institutions’ as the tacit
dimension of power that shapes human interaction. Whereas Douglass North claimed institutions could be reduced to rules, imagined
institutions are known in ways we cannot tell. 相似文献
168.
This article investigates the effect of a Tony nomination or win on the demand facing a Broadway production using a panel
of weekly revenues for Broadway productions from 1996 to 2007. Our results indicate that the effect of a nomination or win
is positive in the week of the announcement and gradually increases in successive weeks, presumably due to publicity and word-of-mouth.
Winners experience an increase in demand as late as 1 year later when awards are publicized for the following season. Moreover,
nominees that do not win the award are penalized heavily in the weeks following the Award announcements. We find that winning
a Tony Award increases a production’s revenues by 12% in the week immediately following the Awards.
相似文献
Lesley ChiouEmail: |
169.
Jordi McKenzie 《Journal of Cultural Economics》2009,33(4):279-299
This study considers a frailty duration approach to modelling the life-length of a sample of 360 films that went into wide
release at the Australian box office from 1 January 2000 to 31 December 2005. The analysis extends previous research by
considering a range of film-specific covariates relating to distribution, production, consumer signals, and weekly performance.
In particular, it is shown that film success (defined in a duration context) responds to previewing, advertising, critical
reviews, and US box office—but not to production budget, star power or opening-week screens. The study also reveals that it
is appropriate to account for unobservable heterogeneity between films in the choice of empirical methodology. 相似文献
170.
Nathaniel Logar 《Minerva》2009,47(4):345-366
How does the research performed by a government mission agency contribute to useable technologies for its constituents? Is it possible to incorporate science policy mechanisms for increasing benefits to users in the decision process? The United States National Institute of Standards &; Technology (NIST) promises research directed towards industrial application. This paper considers the processes that produce science and technology at NIST. The institute’s policies for science provide robust examples for how effective science policies can contribute to the emergence of useful technologies. To progress towards technologies that can be years away, the agency uses several means for integrating the needs of eventual information users into the prioritization process. To accomplish this, NIST units, such as the Materials Science and Engineering Laboratory, incorporate mechanisms for considering user need and project impact into different stages of its scientific decision processes. This, and other specific strategies that the agency utilizes for connecting the supply of science to information demand, provide lessons for generating useable science. 相似文献