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941.
942.
Qingyang Hu Jin Liu Jiuhua Chen Bingmin Yan Yue Meng Vitali B Prakapenka Wendy L Mao Ho-Kwang Mao 《国家科学评论(英文版)》2021,8(4):16-23
Understanding the mineralogy of the Earth''s interior is a prerequisite for unravelling the evolution and dynamics of our planet. Here, we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle (DLM, 1800–2890 km in depth) and observed surprising mineralogical transformations in the presence of water. Ferropericlase, (Mg, Fe)O, which is the most abundant oxide mineral in Earth, reacts with H2O to form a previously unknown (Mg, Fe)O2Hx (x ≤ 1) phase. The (Mg, Fe)O2Hx has a pyrite structure and it coexists with the dominant silicate phases, bridgmanite and post-perovskite. Depending on Mg content and geotherm temperatures, the transformation may occur at 1800 km for (Mg0.6Fe0.4)O or beyond 2300 km for (Mg0.7Fe0.3)O. The (Mg, Fe)O2Hx is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences (Mg2+, Fe3+ and H+). This important phase has a number of far-reaching implications including extreme redox inhomogeneity, deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere. 相似文献
943.
944.
The study of childhood stress provides a useful perspective for assessing children's emotional status. Thematic projective techniques, like the Children's Apperception Test (CAT), may be useful in exploring children's perception of stress. For this purpose, a need-threat analysis is recommended to identify those underlying needs and threats that are likely to make a particular event or situation important, and hence potentially stressful, to an individual child. This paper introduces a scoring system for the CAT based on the analysis of thematic data in terms of five need-threat binaries, which serve as scoring categories. Preliminary data on reliability are presented. 相似文献
945.
946.
Adriana Angel Luis Miguel López-Londoño 《Journal of International and Intercultural Communication》2019,12(1):43-62
We analyze the so-called Socialism of the twenty-first century in which nine South American governments turned to the left over the last 15 years. This South American socialist turn is seen as a delinking from the logics of dependency and pure neoliberalism. To explore the rhetorics that underlie this delinking process, we conducted both a macroanalysis and an intradiscursive rhetorical analysis of the inauguration and most significant speeches of all of the leftist South American presidents elected after 1999. We claim that a common critique of neoliberalism underlies the South American presidents’ speeches, which manifests through specific rhetorics concerning participatory democracy, social inclusion, and environmental protection. When they became transnational, these delinking rhetorics crafted a decolonial critique that calls for more indigenous models of development. 相似文献
947.
Harry F. Dorrell Joseph M. Moore Mark F. Smith Thomas I. Gee 《Journal of sports sciences》2019,37(1):67-73
This study investigated the validity and reliability of the GymAware PowerTool (GPT). Thirteen resistance trained participants completed three visits, consisting of three repetitions of free-weight back squat, bench press, deadlift (80% one repetition maximum), and countermovement jump. Bar displacement, peak and mean velocity, peak and mean force, and jump height were calculated using the GPT, a three-dimensional motion capture system (Motion Analysis Corporation; 150 Hz), and a force plate (Kistler; 1500 Hz). Least products regression were used to compare agreeability between devices. A within-trial one-way ANOVA, typical error (TE; %), and smallest worthwhile change (SWC) were used to assess reliability. Regression analysis resulted in R2 values of >0.85 for all variables excluding deadlift mean velocity (R2 = 0.54–0.69). Significant differences were observed between visits 3-2 for bench press bar displacement (0.395 ± 0.055 m; 0.383 ± 0.053 m), and deadlift bar displacement (0.557 ± 0.034 m; 0.568 ± 0.034 m). No other significant differences were found. Low to moderate TE (0.6–8.8%) were found for all variables, with SWC ranging 1.7–7.4%. The data provides evidence that the GPT can be used to measure kinetic and kinematic outputs, however, care should be taken when monitoring deadlift performance. 相似文献
948.
Georgina L. Kent Brian Dawson Lars R. McNaughton Gregory R. Cox Louise M. Burke Peter Peeling 《Journal of sports sciences》2019,37(3):339-346
This investigation assessed the effect of dietary nitrate (NO3?) supplementation, in the form of beetroot juice (BR), on repeat-sprint performance in normoxia and normobaric hypoxia. 12 male team-sport athletes (age 22.3 ± 2.6 y, VO2peak 53.1 ± 8.7 mL.kg?1.min?1) completed three exercise trials involving a 10 min submaximal warm-up and 4 sets of cycling repeat-sprint efforts (RSE; 9 × 4 s) at sea level (CON), or at 3000 m simulated altitude following acute supplementation (140 mL) with BR (HYPBR; 13 mmol NO3?) or NO3–depleted BR placebo (HYPPLA). Peak (PPO) and mean (MPO) power output, plus work decrement were recorded during the RSE task, while oxygen consumption (VO2) was measured during the warm-up. There were no significant differences observed between HYPBR and HYPPLA for PPO or MPO; however, work decrement was reduced in the first RSE set in HYPBR compared with HYPPLA. There was a moderate effect for VO2 to be lower following BR at the end of the 10 min warm-up (ES = 0.50 ± 0.51). Dietary NO3? may not improve repeat-sprint performance in hypoxia but may reduce VO2 during submaximal exercise. Therefore, BR supplementation may be more effective for performance improvement during predominantly aerobic exercise. 相似文献
949.
Thibaut Méline Ludovic Mathieu Fabio Borrani Robin Candau 《Journal of sports sciences》2019,37(3):347-355
This study aimed to evaluate the effect of simulated training strategies on performance potential in elite short-track speed skaters. Training load and field-based criterion performances from fifteen athletes (10 males, 5 females) were collected over a 3-month training period and the relationship between training loads and performance was computed with a variable dose-response model using a genetic algorithm. Individual simulations of tapers preceded or not preceded by an overload training (OT) were assessed. We obtained a significant correlation between actual and modelled performances (R2 = 0.76 ± 0.07). Regarding model parameters, no significant difference was found between males and females but the time to recover performance tended to be lower in females. Simulations in which the taper parameters were free highlighted that an exponential or a step taper were the most effective for increasing performance compared to a linear taper (p < 0.05). Optimal exponential taper duration after OT was 10.7 ± 2.4d and the optimal load reduction was 75.9 ± 3.7%. OT intensity had the greatest influence on the predicted performance, followed by OT duration, taper decay, and to a lesser extent load reduction during taper and taper duration. Thus, a variable dose-response systems model allows the evaluation of different taper strategies and their potential effect on performance changes. 相似文献
950.
Todd L. Sandel Richard Buttny Mary Varghese 《Journal of Intercultural Communication Research》2019,48(1):52-71
Students were linked virtually across three contexts: U.S., Malaysia, and China. Differences emerged in how student-created messages were constructed and interpreted; these impacted perceived relational affiliation. Messages constructed by students in Malaysia and China exhibited casual talk, greater self-disclosure, requests for personal information, and greater use of emoticons/emoji. Interactions were perceived as informal, friendly, and positive. U.S. students’ messages often showed institutional talk, less self-disclosure, and more attention to the instructor-assigned task. Asian-U.S. student pairs perceived their interactions as formal, less friendly, and less positive. This study shows how online technologies may be afforded and shaped by culture and interaction. 相似文献