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101.
Qihui Wang Feng Zhou Ziyin Shang Philippe Ciais Wilfried Winiwarter Robert B Jackson Francesco N Tubiello Greet Janssens-Maenhout Hanqin Tian Xiaoqing Cui Josep G Canadell Shilong Piao Shu Tao 《国家科学评论(英文版)》2020,7(2):441
Croplands are the single largest anthropogenic source of nitrous oxide (N2O) globally, yet their estimates remain difficult to verify when using Tier 1 and 3 methods of the Intergovernmental Panel on Climate Change (IPCC). Here, we re-evaluate global cropland-N2O emissions in 1961–2014, using N-rate-dependent emission factors (EFs) upscaled from 1206 field observations in 180 global distributed sites and high-resolution N inputs disaggregated from sub-national surveys covering 15593 administrative units. Our results confirm IPCC Tier 1 default EFs for upland crops in 1990–2014, but give a ∼15% lower EF in 1961–1989 and a ∼67% larger EF for paddy rice over the full period. Associated emissions (0.82 ± 0.34 Tg N yr–1) are probably one-quarter lower than IPCC Tier 1 global inventories but close to Tier 3 estimates. The use of survey-based gridded N-input data contributes 58% of this emission reduction, the rest being explained by the use of observation-based non-linear EFs. We conclude that upscaling N2O emissions from site-level observations to global croplands provides a new benchmark for constraining IPCC Tier 1 and 3 methods. The detailed spatial distribution of emission data is expected to inform advancement towards more realistic and effective mitigation pathways. 相似文献
102.
Yang Gao Feng Zhou Philippe Ciais Chiyuan Miao Tao Yang Yanlong Jia Xudong Zhou Butterbach-Bahl Klaus Tiantian Yang Guirui Yu 《国家科学评论(英文版)》2020,7(2):430
In the past three decades, China has built more than 87 000 dams with a storage capacity of ≈6560 km3 and the total surface area of inland water has increased by 6672 km2. Leaching of N from fertilized soils to rivers is the main source of N pollution in China, but the exposure of a growing inland water area to direct atmospheric N deposition and N leaching caused by N deposition on the terrestrial ecosystem, together with increased N deposition and decreased N flow, also tends to raise N concentrations in most inland waters. The contribution of this previously ignored source of N deposition to freshwaters is estimated in this study, as well as mitigation strategies. The results show that the annual amounts of N depositions ranged from 4.9 to 16.6 kg · ha−1 · yr−1 in the 1990s to exceeding 20 kg · ha−1 · yr−1 in the 2010s over most of regions in China, so the total mass of ΔN (the net contribution of N deposition to the increase in N concentration) for lakes, rivers and reservoirs change from 122.26 Gg N · yr−1 in the 1990s to 237.75 Gg N · yr−1 in the 2010s. It is suggested that reducing the N deposition from various sources, shortening the water-retention time in dams and decreasing the degree of regulation for rivers are three main measures for preventing a continuous increase in the N-deposition pollution to inland water in China. 相似文献
103.
104.
Alexandre Bellier Thibault Secheresse Anne Stoeckle Anne-Marie Dols Philippe C. Chaffanjon 《Anatomical sciences education》2020,13(4):427-435
Anatomical dissection on cadavers can be a source of anxiety for medical students. Studies in other stressful settings have shown a reduction in anxiety when there is background music. The objective of this study was to determine if music can have an impact on student anxiety, student satisfaction, and student performance in dissection room. This cluster randomized interventional trial included 187 second-year medical students. The intervention was standardized background music, selected based on the literature, with a tempo of between 60 and 80 bpm. Six balanced clusters were randomized (1:1) to music or no music during dissection sessions. The main assessment criterion was a validated self-evaluation scale score for anxiety, the State Trait Anxiety Inventory. Student satisfaction was measured using a visual analog scale and dissection performance was evaluated by an examination. The outcomes were analyzed with mixed models adjusted on group effect, chronic anxiety, and confounding factors. A significant (58%) relative decrease in acute anxiety, odds ratio 0.423 [0.160; 0.710] was found for the music intervention group. Music also had a positive impact on performance with students in the intervention group attaining higher grades than those in the control group (0.42/10 higher, P = 0.0016). The study also showed a nonsignificant increase in satisfaction with 0.37 extra points (P = 0.137) in the intervention group. Background music had a significant impact on anxiety in the dissection room and on technical and theoretical performance in the subsequent anatomy examination. This music intervention could be extended to other stressful work environments. 相似文献
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106.
Agricultural science and technology (S&T) is under great scrutiny. Reorientation towards more holistic approaches, including agroecology, has recently been backed by a global international assessment of agriculture S&T for development (IAASTD). Understanding the past and current trends of agricultural S&T is crucial if such recommendations are to be implemented. This paper shows how the concepts of technological paradigms and trajectories can help analyse the agricultural S&T landscape and dynamics. Genetic engineering and agroecology can be usefully analysed as two different technological paradigms, even though they have not been equally successful in influencing agricultural research. We used a Systems of Innovation (SI) approach to identify the determinants of innovation (the factors that influence research choices) within agricultural research systems. The influence of each determinant is systematically described (e.g. funding priorities, scientists’ cognitive and cultural routines etc.). As a result of their interactions, these determinants construct a technological regime and a lock-in situation that hinders the development of agroecological engineering. Issues linked to breaking out of this lock-in situation are finally discussed. 相似文献
107.
108.
Vesna Matović Suzana Erić Aleksandar Kremenović Philippe Colomban Danica Srećković-Batoćanin Nenad Matović 《Journal of Cultural Heritage》2012,13(2):175-186
Black crusts formed on limestone built into the King's Gate represent the most important process in stone deterioration that is occurring in this part of the monumental complex of the Belgrade Fortress (Serbia). Of special importance is the association of salts (namely gypsum and syngenite). Syngenite is a common secondary deposit on granite monuments and on medieval stained glass (i.e., on K-containing materials). However, its appearance over calcareous substrates is not apparent, particularly in cases where cement mortar was not used for bounding. The origins of the potassium and sulphate ions required for syngenite formation are related to meteoritic water, which penetrates the soil above the arch of King's Gate. Water dissolves some soil components and becomes enriched with various ions before coming into contact with the limestone blocks. Enriched water contains two times more K+ and SO42? ions than pristine meteoritic water does. The source of the required ions is potassium-sulphate that is present in agricultural fertilisers that are used above the monument. The proposed mechanism for syngenite formation was additionally supported with laboratory experiment. The results of X-ray diffractometry and SEM-EDS analyses of limestone treated with potassium-sulphate solution and sulphuric acid suggest the possibility that the syngenite was formed over calcite:CaCO3 + K2SO4 + H2SO4 → K2Ca(SO4)2 H2O + CO2↑However, the complex mechanisms of gypsum and syngenite formation under natural conditions (variable concentration of potassium and sulphate ions, intermediates phases, temperature changes, humidity, the amount of disposable water etc.) do not exclude the possibility of syngenite formation over gypsum. 相似文献
109.
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
110.
Nadia Leroy Pascal Bressoux Phillippe Sarrazin David Trouilloud 《European Journal of Psychology of Education - EJPE》2007,22(4):529-545
According to self-determination theory, when teachers establish an autonomy supportive climate in the classroom, students
demonstrate high levels of self-determination and are intrinsically motivated. The aim of this study was to identify factors
leading teachers (N=336) to report that they create such a climate. We conducted a path analysis in order to examine the respective
roles of teachers’ implicit theories, their seniority, and their perceptions of pressures at work. We also attempted to find
out whether these personal and contextual variables have a direct influence or are mediated by teachers’ self-efficacy. Our
first finding was that a theory of academic ability as a fixed trait caused a drop in the teachers’ reported support for autonomy.
On the other hand, the belief that academic abilities can be improved through students’ own efforts indirectly favored an
autonomy supportive climate by acting positively on the teachers’ self-efficacy. Also, seniority had a significant positive
effect on autonomy support that was direct, but was also mediated by self-efficacy. Finally, perceived pressures had a negative
impact on reported autonomy support, but their influence was also mediated by self-efficacy. 相似文献