In vitro remineralization of hybrid layers using biomimetic analogs     

Hui-ping Lin  Jun Lin  Juan Li  Jing-hong Xu  Christian Mehl 《Journal of Zhejiang University. Science. B》2016,17(11):864-873

Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation.  相似文献   

Fans and states at work: a Ghanaian fan trip to the FIFA World Cup 2010 in South Africa     

Erdmute Alber & Christian Ungruhe 《Soccer & Society》2016,17(1):18-39

The FIFA World Cup for men (hereafter referred to as the FIFA World Cup) is possibly the biggest global media event. Winning or losing often gives rise to expressions of collective degrees of national pride or disappointment. But, it is not only the performance of the teams that is of significance in this respect; the devotion of fans to the game and their loyalty to their own national team are also an important vehicle of identity and self-affirmation as a nation. Thus, no country can afford to dispense with the travelling model of the enthusiastic fan as a representative of national identity. Through an ethnographic study of Ghana’s state-financed fan trip to the FIFA World Cup 2010 in South Africa, we will show how the actors involved (government, opposition, fans and media) negotiate national identity and representation.  相似文献   

Unfair play in World Cup qualification? An analysis of the 1998–2010 FIFA World Cup performances and the bias in the allocation of tournament berths     

Christian Stone  Michel Rod 《Soccer & Society》2016,17(1):40-57

This paper reviews the FIFA World Cups 1998–2010 with data available from the FIFA website and assesses the performance of each region in relation to the number of World Cup qualifications spots that the region is awarded. We raise the issue of whether FIFA should be more concerned with the participation of more members from its federations in the World Cup than the financial gain from doing so. Our non-econometric analysis illustrates that the current allocation may be resulting in the awarding of qualification spots to teams that if not unfair, certainly warrants discussion. We seek to demonstrate that the current system of qualification is based neither on ensuring the qualification of the best 32 teams in the world, nor does it fairly allocate qualification spots on the number of teams per federation or any other metric. We conclude with a plea for more transparent allocation processes.  相似文献   

Predictive value of ventilatory inflection points determined under field conditions     

Christian Heyde  Hubert Mahler  Kai Roecker  Albert Gollhofer 《Journal of sports sciences》2016,34(9):787-793

The aim of this study was to evaluate the predictive potential provided by two ventilatory inflection points (VIP₁ and VIP₂) examined in field without using gas analysis systems and uncomfortable facemasks. A calibrated respiratory inductance plethysmograph (RIP) and a computerised routine were utilised, respectively, to derive ventilation and to detect VIP₁ and VIP₂ during a standardised field ramp test on a 400 m running track on 81 participants. In addition, average running speed of a competitive 1000 m run (S_1k) was observed as criterion. The predictive value of running speed at VIP₁ (S_VIP1) and the speed range between VIP₁ and VIP₂ in relation to VIP₂ (VIP_SPAN) was analysed via regression analysis. VIP_SPAN rather than running speed at VIP₂ (S_VIP2) was operationalised as a predictor to consider the covariance between S_VIP1 and S_VIP2. S_VIP1 and VIP_SPAN, respectively, provided 58.9% and 22.9% of explained variance in regard to S_1k. Considering covariance, the timing of two ventilatory inflection points provides predictive value in regard to a competitive 1000 m run. This is the first study to apply computerised detection of ventilatory inflection points in a field setting independent on measurements of the respiratory gas exchange and without using any facemasks.  相似文献   

Bedingungen der Bindungswirkung inkrementeller Normen in Fußballvereinen     

Christian Rullang  Eike Emrich  Christian Pierdzioch  Freya Gassmann 《Sportwissenschaft》2016,46(4):275-286

Sports clubs depend on the pooling of resources by their members. The supportive distribution of the resources within a club is facilitated in particular by the effectiveness of incremental standards. A basic prerequisite for a fair distribution of resources is a minimum of community spirit among the members. Based on a nationwide survey of football clubs and an ordinal logistic regression model, factors were determined that reflect the extent of the community spirit within a club. The opening up of the club by payment to players and perceived problems with acquiring and binding of volunteers are associated with a reduction of community spirit. In contrast, the perception that the club activities can be continued in the long term shows a positive correlation to a highly developed community spirit.  相似文献   

Bilateral practice improves dominant leg performance in long jump     

Anne Focke  Sina Spancken  Christian Stockinger  Benjamin Thürer  Thorsten Stein 《European Journal of Sport Science》2016,16(7):787-793

Benefits of bilateral practice both for the non-dominant and for the dominant body side have been shown in several studies. Thereby, most of the studies included movement tasks of the upper extremity or investigated sports games in which the ability of acting bilaterally is an essential basis for success and, thus, a bilateral practice is reasonable anyway. Individual unilaterally performed sports including movement tasks of the lower extremity are rarely investigated. Therefore, the aim of our study was to test if contralateral transfer due to bilateral practice can be found in an unilaterally performed sport including the lower extremity. We trained and tested 61 adolescent athletes in long jump to compare the jumping performance of the dominant leg after a 12-week practice period between two groups: a bilateral practice group that practiced specific long jump exercises with both the dominant and non-dominant leg and an unilateral practice group that practiced specific long jump exercises only with the dominant leg. Results showed a superior effect of bilateral practice compared to unilateral practice regarding the jumping performance of the dominant leg. The performance increase at post-test and retention-test for the dominant limb was significantly higher for the bilateral practice group (pre-to-post: 5.2%, pre-to-retention: 7.4%) compared to the unilateral practice group (pre-to-post: 3.4%, pre-to-retention: 4.5%). Thus, bilateral practice should be established in the early practice programmes of track and field athletes to improve the performance of the dominant take-off leg.  相似文献   

Effects of high-complexity and high-cognitive-level instructional tasks in biology lessons on students’ factual and conceptual knowledge     

Christian Förtsch  Sonja Werner  Lena von Kotzebue  Birgit J. Neuhaus 《Research in Science & Technological Education》2018,36(3):353-374

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Effects of critical thinking on multiple-document comprehension     

Tarchi  Christian  Mason  Lucia 《European Journal of Psychology of Education - EJPE》2020,35(2):289-313

European Journal of Psychology of Education - The purpose of this study was to test the relationships between critical thinking, prior topic knowledge and beliefs, and multiple-document...  相似文献   

Why extraversion is not enough: the mediating role of initial peer network centrality linking personality to long-term academic performance     

Lisa Thiele  Nils Christian Sauer  Simone Kauffeld 《Higher Education》2018,76(5):789-805

Academic performance (i.e., grade point average) determines career entry factors as well as career success and is thus crucial for students’ future careers. Besides individual factors such as personality traits, individuals’ social embeddedness has been shown to enhance performance. Regarding academic performance, relationships to fellow students (peers), which bundle into one’s developmental network, are a valuable source of psychosocial and career support because occupying central positions within a social network provides the benefit of being able to access career-enhancing resources. Integrating individual and social-contextual factors for the purpose of examining academic performance is therefore plausible. Research results indicate that personality, especially extraversion, might predict performance through network centrality. In this study, we examined this assumption by focusing on extraversion and centrality in the peer developmental network of recently acquainted German psychology bachelor students (N?=?47, 15% male). In a longitudinal design, we analyzed the impact of extraversion and centrality on students’ academic performance at the end of their studies. Results revealed that centrality (i.e., popularity) mediates the relationship of extraversion with academic performance, indicating that extraverted students (regardless of their agreeableness) are more popular among their peers, which, in turn, enhances their academic performance. That is, the likelihood of getting superior final grades depends on whether students manage to attract peers at the very beginning of their university life, which is easier for extraverts. These findings emphasize the importance of the social embeddedness of people, highlight its long-term effects on performance, and yield several implications for research and practice.  相似文献   

Some thoughts on the new approaches to science education     

Christian Souchon 《Prospects》1985,15(4):535-540

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