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441.
We use the results of a public opinion survey we carried out in 2012 on a sample of the Spanish adult population to offer a plausible explanation of one of the main conundrums of primary and secondary school teachers' prestige, not only in Spain, i.e. that, contrary to public discourse and to teachers' perceptions, this prestige has not fallen in the last decades, but has remained middle to high. The estimates of teachers' prestige made by the public are the same (roughly, around 70 in a 0 to 100 scale) as those that were measured in the early 1990s. However, a clear majority of the public believes that teachers' prestige has fallen in the last decades, reiterating a cliché that is widespread in the Spanish public sphere, especially among teachers. We hypothesise that the perception of the falling prestige is much more a matter of a public space dominated by the media than of a public space that is more confined to everyday experiences and to the citizens' basic values. We support our hypothesis with pieces of empirical evidence related, on the one hand, to the association of that perception with media consumption variables in our survey, and, on the other, to media (negative) treatment of teachers' prestige. In our argument, we are also helped by a literature that is not usually dealt with in studies of teachers' prestige: that of media influence in the formation of public opinions regarding other people's opinions. 相似文献
442.
The principal contribution of this note is to avoid the parametric resonance effect and attenuate the payload oscillations in an overhead-crane system subject to periodic variations in the base support. Considering an appropriate sliding output with relative degree one, we present the sliding mode control design based on the Super-Twisting Algorithm (STA), ensuring finite time convergence to the desired sliding surface for the linear periodic system with Lipschitz continuous matched and unmatched uncertainties bounded together by their gradients by known functions. The suggested approach also provides chattering phenomenon attenuation. Obtained results are verified experimentally. 相似文献
443.
In this work a procedure for obtaining polytopic λ-contractive sets for Takagi–Sugeno fuzzy systems is presented, adapting well-known algorithms from literature on discrete-time linear difference inclusions (LDI) to multi-dimensional summations. As a complexity parameter increases, these sets tend to the maximal invariant set of the system when no information on the shape of the membership functions is available. λ-contractive sets are naturally associated to level sets of polyhedral Lyapunov functions proving a decay-rate of λ. The paper proves that the proposed algorithm obtains better results than a class of Lyapunov methods for the same complexity degree: if such a Lyapunov function exists, the proposed algorithm converges in a finite number of steps and proves a larger λ-contractive set. 相似文献
444.
445.
Abstract In research on the importance of the possession of the ball in soccer, little attention has been paid to its determinants. Using data from 170 matches of the 2003 – 2004 Spanish Soccer League, we explain why differences in the possession of the ball among teams are so great. In particular, four variables are examined: evolving match status (i.e. whether the team is winning, losing or drawing), venue (i.e. playing at home or away), and the identities of the team and the opponent in each match. Results of linear regression analysis show that these four variables are statistically significant and together explain most of the variance in possession. In short, home teams have more possession than away teams, teams have more possession when they are losing matches than when winning or drawing, and the identity of the opponent matters – the worse the opponent, the greater the possession of the ball. Combinations of these variables could be used to develop a model that predicts possession in soccer. 相似文献
446.
Pedro T. Esteves Duarte Araújo Keith Davids Luís Vilar Bruno Travassos Carlos Esteves 《Journal of sports sciences》2013,31(12):1285-1293
Abstract In this study, we examined the effects of relative positioning of attacker–defender dyads to the basket on interpersonal coordination tendencies in basketball. To achieve this aim, four right-hand dominant basketball players performed in a 1 vs. 1 sub-phase, at nine different playing locations relative to the basket (from 0° to 180°, in 20° increments). Performers’ movement displacement trajectories were video-recorded and digitized in 162 trials. Results showed that interpersonal coordination tendencies changed according to the scaling of the relative position of performers to the basket. Stable in-phase modes of coordination were observed between performers’ longitudinal and lateral displacements (50.47% and 43.02%) on the left side of the court. On the right side of the court, a shift in the dominant mode of coordination was observed to a defender lead-lag of ?30°, both for longitudinal and lateral displacements (30.51% and 32.65%). These results suggest how information about dribbler hand dominance and relative position to the basket may have constrained attacker–defender coordination tendencies in 1 vs. 1 sub-phases of basketball. 相似文献
447.
Maedeh Roushan Parminder Kaur Alena Karpusenko Preston J. Countryman Carlos P. Ortiz Shuang Fang Lim Hong Wang Robert Riehn 《Biomicrofluidics》2014,8(3)
We present an analytic technique for probing protein-catalyzed transient DNA loops that is based on nanofluidic channels. In these nanochannels, DNA is forced in a linear configuration
that makes loops appear as folds whose size can easily be quantified. Using this technique, we study
the interaction between T4 DNA ligase and DNA. We find that T4 DNA ligase binding changes the physical characteristics of the DNA
polymer, in particular
persistence length and effective width. We find that the rate of DNA fold unrolling is significantly reduced
when T4 DNA ligase and ATP
are applied to bare DNA.
Together with evidence of T4 DNA ligase bridging two different segments of DNA based on AFM imaging, we thus conclude that ligase
can transiently stabilize folded
DNA configurations by coordinating genetically distant DNA stretches. 相似文献
448.
449.
Herrera-Cubides Jhon Francined Gaona-Garca Paulo Alonso Montenegro-Marn Carlos Enrique Snchez-Alonso Salvador 《Education and Information Technologies》2022,27(2):1811-1839
Education and Information Technologies - Nowadays, information and communication technologies (ICTs) and virtual training have increased the use of educational resources. This growth use has... 相似文献