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131.
Jinren Ni Haizhen Wang Tao Ma Rong Huang Philippe Ciais Zhe Li Yao Yue Jinfeng Chen Bin Li Yuchun Wang Maosheng Zheng Ting Wang Alistair G L Borthwick 《国家科学评论(英文版)》2022,9(6)
Dams are often regarded as greenhouse gas (GHG) emitters. However, our study indicated that the world''s largest dam, the Three Gorges Dam (TGD), has caused significant drops in annual average emissions of CO2, CH4 and N2O over 4300 km along the Yangtze River, accompanied by remarkable reductions in the annual export of CO2 (79%), CH4 (50%) and N2O (9%) to the sea. Since the commencement of its operation in 2003, the TGD has altered the carbonate equilibrium in the reservoir area, enhanced methanogenesis in the upstream, and restrained methanogenesis and denitrification via modifying anoxic habitats through long-distance scouring in the downstream. These findings suggest that ‘large-dam effects’ are far beyond our previous understanding spatiotemporally, which highlights the fundamental importance of whole-system budgeting of GHGs under the profound impacts of huge dams. 相似文献
132.
Bastiaan Breine Philippe Malcolm Ine Van Caekenberghe Pieter Fiers Edward C. Frederick Dirk De Clercq 《Journal of sports sciences》2017,35(15):1556-1564
This study assessed kinematic differences between different foot strike patterns and their relationship with peak vertical instantaneous loading rate (VILR) of the ground reaction force (GRF). Fifty-two runners ran at 3.2 m · s?1 while we recorded GRF and lower limb kinematics and determined foot strike pattern: Typical or Atypical rearfoot strike (RFS), midfoot strike (MFS) of forefoot strike (FFS). Typical RFS had longer contact times and a lower leg stiffness than Atypical RFS and MFS. Typical RFS showed a dorsiflexed ankle (7.2 ± 3.5°) and positive foot angle (20.4 ± 4.8°) at initial contact while MFS showed a plantar flexed ankle (?10.4 ± 6.3°) and more horizontal foot (1.6 ± 3.1°). Atypical RFS showed a plantar flexed ankle (?3.1 ± 4.4°) and a small foot angle (7.0 ± 5.1°) at initial contact and had the highest VILR. For the RFS (Typical and Atypical RFS), foot angle at initial contact showed the highest correlation with VILR (r = ?0.68). The observed higher VILR in Atypical RFS could be related to both ankle and foot kinematics and global running style that indicate a limited use of known kinematic impact absorbing “strategies” such as initial ankle dorsiflexion in MFS or initial ankle plantar flexion in Typical RFS. 相似文献
133.
134.
Guoyi Zhou Shan Xu Philippe Ciais Stefano Manzoni Jingyun Fang Guirui Yu Xuli Tang Ping Zhou Wantong Wang Junhua Yan Gengxu Wang Keping Ma Shenggong Li Sheng Du Shijie Han Youxin Ma Deqiang Zhang Juxiu Liu Shizhong Liu Guowei Chu Qianmei Zhang Yuelin Li Wenjuan Huang Hai Ren Xiankai Lu Xiuzhi Chen 《国家科学评论(英文版)》2019,6(4):746
Soil organic carbon (SOC) plays critical roles in stabilizing atmospheric CO2 concentration, but the mechanistic controls on the amount and distribution of SOC on global scales are not well understood. In turn, this has hampered the ability to model global C budgets and to find measures to mitigate climate change. Here, based on the data from a large field survey campaign with 2600 plots across China''s forest ecosystems and a global collection of published data from forested land, we find that a low litter carbon-to-nitrogen ratio (C/N) and high wetness index (P/PET, precipitation-to-potential-evapotranspiration ratio) are the two factors that promote SOC accumulation, with only minor contributions of litter quantity and soil texture. The field survey data demonstrated that high plant diversity decreased litter C/N and thus indirectly promoted SOC accumulation by increasing the litter quality. We conclude that any changes in plant-community composition, plant-species richness and environmental factors that can reduce the litter C/N ratio, or climatic changes that increase wetness index, may promote SOC accumulation. The study provides a guideline for modeling the carbon cycle of various ecosystem scales and formulates the principle for land-based actions for mitigating the rising atmospheric CO2 concentration. 相似文献
135.
Philippe Oberling Adam S. Bristol Helena Matute Ralph R. Miller 《Learning & behavior》2000,28(2):172-186
Miller and Matute (1996) showed that blocking is attenuated when the blocked conditioned stimulus (CS) is “biologically significant” (i.e., when the CS has the potential to elicit vigorous responding of any kind). To the extent that blocking is representative of cue competition, this finding suggests that biological significance protects CSs against cue competition effects in general. In the present experiments, we tested this possibility by examining the influence of biological significance of CSs on other examples of cue competition, namely, overshadowing, the relative stimulus validity effect, and the degraded contingency effect in rats. In Experiment 1, we found that intense auditory stimuli induced transient unconditioned lick suppression, thereby indicating that intense sounds were of high inherent biological significance. In Experiment 2A, we found that cues with high inherent biological significance were protected from overshadowing. In Experiment 2B, this finding was extended to cues with high acquired biological significance, which was obtained through prior pairings with a reinforcer of the valence opposite to that used in the overshadowing treatment. In Experiments 3 and 4, we found that cues with high inherent biological significance attenuated the relative validity effect and the degraded contingency effect, respectively. These results lend support to the view that biological significance (inherent and acquired) protects stimuli from cue competition effects, a finding that is problematic for many contemporary theories of learning. 相似文献
136.
Bård Erlend Solstad Andreas Stenling Yngvar Ommundsen Bente Wold Jean-Philippe Heuzé Philippe Sarrazin 《Journal of sports sciences》2020,38(6):626-643
ABSTRACTThe present study examined the psychometric properties of the coach-adapted version of the Empowering and Disempowering Motivational Climate Questionnaire (EDMCQ) using Bayesian structural equation modelling (BSEM). The sample included 780 (Mage = 36.4; SD = 10.8; males n = 698; females n = 54; 28 participants did not report sex) youth sport coaches representing five European countries (i.e., England, France, Greece, Norway, and Spain). The results did not support a 34-item five-factor, hierarchical, a two-factor BSEM, or a bifactor BSEM model across the participating countries. However, the results supported a reduced 19-item first-order, two-factor BSEM model that largely showed approximate metric invariance, but not approximate scalar invariance across the five countries. The pool of items constituting empowering and disempowering motivational climates should be refined to further enhance the empirical operationalisation of the coach-adapted version of the EDMCQ. Advancing the quality of translation-back-translation procedures across cultures and conducting multi-national pilot testing seems warranted as well. These recommendations may help to identify the distinctive aspects of each underlying sub-dimension of the EDMCQ, where coaches are the respondents, and pave the way for further examination of the proposed hierarchical multidimensional factor structure and the cross-cultural equivalence of the EDMCQ for this population. 相似文献
137.
138.
Philippe Vonnard 《Soccer & Society》2019,20(7-8):1025-1040
ABSTRACTSince the 1920s, many European exchanges began to exist in the domain of football. However, it was during the 1950s that a European scale was established primarily due to the creation of UEFA (Union of European Football Associations) in 1954, which quickly organized the first European tournament in the game’s history– The European Champions Clubs’ Cup. The present essay argues that Europeanization of the game has to be understood in a long-term perspective. The papers examines the creation and development of three competitions as key defining events, which represented different stages of the Europeanization of the game: Mitropa Cup (created in 1927), European Champion Clubs’ Cup (created in 1955) and UEFA Cup (created in 1971). Thus, afocus on these cases can help us better understand the background of the Europeanization of the game which happened during the 1990s. 相似文献
139.
Xavier Robert-Lachaine René A. Turcotte Philippe C. Dixon David J. Pearsall 《Sports Engineering》2012,15(4):197-206
Dynamic forces and range of motion (ROM) were measured during on-ice skating using a standard hockey skate and a modified skate (MS) with an altered tendon guard and eyelet configuration. The objective of this study was to determine if these modifications resulted in biomechanical and performance changes during on-ice skating skills. The right skate of each type was instrumented with a calibrated strain gauge force transducer system to measure medial?Clateral and vertical forces during ice skating. In addition, a goniometer was placed about the ankle and rear foot to measure ROM during skating. Ten subjects executed three skills: forward skating, crossovers inside foot and crossovers outside foot. The MS demonstrated significant gains of 5°?C9° in dorsi-plantarflexion ROM (p?<?0.05). Total peak force occurred later during plantarflexion, suggesting a more prolonged and effective force generation with the MS during a given skating stride. A 14?C20?% increase (p?>?0.05) in mean work and power output was noted with the MS, although no improved times were observed during the skating skills. Potentially, some players may need a period of familiarization to take advantage of the design alterations of the MS. 相似文献
140.
Aleksandra R. Budarick Jaymee R. Shell Shawn M. K. Robbins Tom Wu Philippe J. Renaud David J. Pearsall 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(5):601-617
ABSTRACT The skating acceleration to maximal speed transition (sprint) is an essential skill that involves substantial lower body strength and effective propulsion technique. Coaches and athletes strive to understand this optimal combination to improve performance and reduce injury risk. Hence, the purpose of this study was to compare body centre of mass and lower body kinematic profiles from static start to maximal speed of high calibre male and female ice hockey players on the ice surface. Overall, male and female skaters showed similar centre of mass trajectories, though magnitudes differed. The key performance difference was the male’s greater peak forward skating speed (8.96 ± 0.44 m/s vs the females’ 8.02 ± 0.36 m/s, p < 0.001), which was strongly correlated to peak leg strength (R 2 = 0.81). Males generated greater forward acceleration during the initial accelerative steps, but thereafter, both sexes had similar stride-by-stride accelerations up to maximal speed. In terms of technique, males demonstrated greater hip abduction (p = 0.006) and knee flexion (p = 0.026) from ice contact to push off throughout the trials. For coaches and athletes, these findings underscore the importance of leg strength and widely planted running steps during the initial skating technique to achieve maximal skating speed over a 30 m distance. 相似文献