Los libros del año 1992     

Antonio Guerrero  Lourdes Montero  Amelia Alvarez  José A. León  Nuria Carriedo  Pablo del Río 《Infancia y Aprendizaje》2013,36(61):125-144

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Grade level, study time, and grade retention and their effects on motivation, self-regulated learning strategies, and mathematics achievement: a structural equation model     

Pedro Rosário  José Carlos Núñez  António Valle  Julio González-Pienda  Abílio Lourenço 《European Journal of Psychology of Education - EJPE》2013,28(4):1311-1331

The present study complements previous research findings with new data to improve our understanding of the relationship between motivational variables and academic performance in math mediated by self-regulated learning (SRL). A structural equation model with predictor (i.e., grade retention, grade level, and study time), process (i.e., perceived usefulness of SRL strategies, self-efficacy for the use of SRL strategies, and reported use of SRL), and product variables (i.e., academic achievement in mathematics) is proposed. The model was analyzed in two samples of data (calibration and validation samples). The first sample served to fit and respecify the model, and the second one was used to analyze the consistency of the findings of the first sample. A sample of 756 middle school Portuguese students participated in the current study. The results indicate that SRL is positively and significantly related to academic achievement and that the latter is, in turn, powerfully determined by perceived usefulness and self-efficacy, although students’ reported use of SRL strategies decreases from 7th to 9th grades. Self-efficacy and perceived usefulness of SRL strategies were also found to decrease as grade retention increased. These results are discussed with regard to the relevance of self-efficacy and perceived usefulness of SRL strategies in increasing academic achievement.  相似文献   

Why Teachers Should Know Spanish     

Dr. Maria Luisa Alvarez Harvey 《Clearing house (Menasha, Wis.)》2013,86(7):333-336

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Problem posing based on investigation activities by university students     

João Pedro da Ponte  Ana Henriques 《Educational Studies in Mathematics》2013,83(1):145-156

This paper reports a classroom-based study involving investigation activities in a university numerical analysis course. The study aims to analyse students' mathematical processes and to understand how these activities provide opportunities for problem posing. The investigations were intended to stimulate students in asking questions, to trigger their thinking processes, to promote their ability to investigate and to support them in learning numerical analysis' concepts and procedures. The results show that the investigations provided opportunities for students to experience mathematical processes, including posing questions, formulating and testing conjectures and, to some extent, proving results. They also provide some understanding about the role of problem posing in these processes. Posing questions occurred mainly in an implicit way, in the interpretation of tasks and in identifying regularities, analysing graphs and testing cases. The conjectures were often based on pattern identification or data manipulation, and the students tended to accept them without testing or proving. The students also proposed alternative formulations for the initial questions and posed new problems from their explorations and attempts to refine previous conjectures.  相似文献   

Rapid production of protein-loaded biodegradable microparticles using surface acoustic waves     

Mar Alvarez  Leslie Y. Yeo  James R. Friend    Milan Jamriska 《Biomicrofluidics》2009,3(1)

We present a straightforward and rapid surface acoustic wave (SAW) atomization-based technique for encapsulating proteins into 10 μm order particles composed of a biodegradable polymeric excipient, using bovine serum albumin (BSA) as an exemplar. Scans obtained from confocal microscopy provide qualitative proof of encapsulation and show the fluorescent conjugated protein to be distributed in a relatively uniform manner within the polymer shell. An ELISA assay of the collected particles demonstrates that the BSA survives the atomization, particle formation, and collection process with a yield of approximately 55%. The SAW atomization universally gave particles with a textured morphology, and increasing the frequency and polymer concentration generally gave smaller particles (to 3 μm average) with reduced porosity.  相似文献   

Social interactions and cognitive effects in contexts of area-comparison problem solving     

Pedro Cobo  Josep M. Fortuny 《Educational Studies in Mathematics》2000,42(2):115-140

The paper we present is a case study which has two objectives: the identification of the interactions between pairs of 16 and17-year-old students related to problem solving and the influence of such interactions in their cognitive development. To achieve these aims, we consider problems associated with a definite conceptual structure – problems comparing flat surface areas –, and we focus the analysis of the interactions on the point of view of the thematic and interlocutive dimensions of the discourse. Such analysis has allowed us to identify a wide typology of exchanges, and, from this, to outline four models of interaction -alternative, guided, relaunching, and co-operative. In the cases analysed, these interactions significantly influence the individual development of cognitive and heuristic abilities in the problem solving process. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Changes in mechanical properties of sprinting during repeated sprint in elite rugby sevens athletes     

Pedro Jiménez-Reyes  Matt Cross  Alex Ross  Pierre Samozino  Matt Brughelli  Nicholas Gill 《European Journal of Sport Science》2019,19(5):585-594

This study aimed to analyse fatigue-induced changes in mechanical sprinting properties during a specific repeated-sprint test in elite rugby sevens athletes. Twenty elite rugby sevens players performed ten 40?m sprints on a 30?s cycle with participant’s running back and forth in a marked lane. Radar was used to assess maximal overground sprint performance over each 40?m. Macroscopic mechanical properties (maximal horizontal force (F₀), maximal horizontal power (P_max), maximal ratio of horizontal force (RF_peak), decrease in the ratio of horizontal-to-total force (D_RF), total force and maximal sprinting velocity (v₀)) were drawn from horizontal force velocity relationships, using a validated method applied to the speed–time data. Fatigue-induced changes were analysed comparing the first sprint to an average of 2^nd-4^th, 5^th-7^th and 8^th-10^th. Repeated-sprint ability (RSA) testing induced substantial changes in the maximal velocity component, with a decrease (–15%) in v₀ (effect size (ES)?=?–2.46 to –4.98), and to a lower extent (–5.9%) in the maximal force component F₀ (ES?=?–0.59). D_RF moderately decreased (14%; ES=–0.76–1.11), and RF_peak largely decreased in the later sprints (ES?=?–0.32 to –1.27). Fatigue observed in this RSA test appeared to have a greater effect on the technical ability to produce horizontal force at high velocities, likely due to an alteration in the ability to maintain horizontally oriented force application when velocity increases rather than during the initial acceleration phase, but also the overall force production capacity. The ability to maintain forward-oriented force at high velocities is of central importance for identifying fatigue and monitoring load.  相似文献   

Biomechanical analyses of synchronised swimming standard and contra-standard sculling     

Lara Elena Gomes  Vera Diogo  Flávio Antônio de Souza Castro  João Paulo Vilas-Boas  Ricardo J. Fernandes  Pedro Figueiredo 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(4):354-365

Synchronised swimming involves a variety of sculling movements essential for body support and propulsion but its study is scarce. We aimed to biomechanically compare standard and contra-standard sculling techniques, and to observe the relationship between measures. Six synchronised swimmers performed two, 30 s maximal intensity, fully tethered standard and contra-standard sculling motions. Kinetic and kinematic data were obtained using a load-cell and underwater cameras, respectively. Force decreased along both techniques’ bouts, but no differences in-between techniques were noted for any kinetic variables. Standard sculling presented a higher cycle rate and a lower elbow mean angle than the contra-standard sculling (2.4 ± 0.3 vs. 2.0 ± 0.2 cycles/s and 134.1 ± 5.8 and 141.5 ± 4.7°, p < 0.05). In the standard sculling, by removing and maintaining the variation between participants (r _w and r, respectively), the absolute mean force was directly related with cycle rate (r _w  = 0.60) and wrist angular velocity during flexion (r = 0.82), while in the contra-standard condition the force was inversely associated with wrist mean angle (r = ?0.95) and directly with hand speed (r _w  = 0.76), and elbow angular velocity (r _w  ≈ 0.60). Therefore, technique learning and training require different attention by coaches and swimmers.  相似文献   

Analysis of foot strike pattern,rearfoot dynamic and foot rotation over childhood. A cross-sectional study     

Pedro Ángel Latorre Román  Fernando Redondo Balboa  Juan Párraga Montilla  Víctor Manuel Soto Hermoso  Pedro José Consuegra González  Felipe García Pinillos 《Journal of sports sciences》2019,37(5):477-483

The purpose of this study was to determine the foot strike patterns (FSP), rearfoot position at initial contact (RPic, i.e., No INV/EVE) and foot rotation in children in relation to age. A total of 932 children aged 3 to 16 years participated in this study. A sagittal and frontal-plane video was recorded using a high-speed camcorder to analyse these variables. There is a significant increase (p < 0.001) of rearfoot strike patterns (RFS) prevalence in relation to age; e.g. preschool children (3–6 years old) displayed an RFS prevalence 46.65% and the adolescent population(15–16 years old) an RFS prevalence 92.20%. The total RFS prevalence in all samples was 69.25%. There was a significant reduction (p < 0.001) of prevalence of RPic in relation to age groups; preschool children displayed a prevalence of RPic 60.37% and the adolescent population 10%. There was a significant reduction (p < 0.001) of prevalence of no foot rotation in relation to age groups; preschool children displayed a prevalence of no foot rotation 48.95% and the adolescent population 13.55%. In conclusion, FSP in children are influenced by age. It is noteworthy that the RFS prevalence of children is lower in comparison to the adult population.  相似文献   

Accelerometer and self-reported measures of sedentary behaviour and associations with adiposity in UK youth     

Robert J. Noonan  Danielle Christian  Lynne M. Boddy  Pedro F. Saint-Maurice  Gregory J. Welk  Paul R. Hibbing 《Journal of sports sciences》2019,37(16):1919-1925

This study used accelerometer and self-report measures of overall sedentary time (ST) and screen time behaviours to examine their respective associations with adiposity among UK youth. Participants (Year groups 5, 8, and 10; n=292, 148 girls) wore the SenseWear Armband Mini accelerometer for eight days and completed the Youth Activity Profile, an online report tool designed to estimate physical activity and ST.Stature, body mass and waist circumference were measured to classify adiposity outcomes (overweight/obese and central obesity). One-way between groups ANOVA and adjusted linear, logistic and multinomial logistic regression analyses were conducted. There was a significant main effect of age on total ST across the whole week (F(2, 289)=41.64, p≤0.001). ST increased monotonically across Year 5 (581.09±107.81 min·dˉ¹), 8 (671.96±112.59 min·dˉ¹) and 10 (725.80±115.20 min·dˉ¹), and all pairwise comparisons were significant at p≤0.001. A steep age-related gradient to mobile phone use was present (p≤0.001). ST was positively associated with adiposity outcomes independent of moderate-to-vigorous intensity physical activity (MVPA; p≤0.001). Engaging in >3 hours of video gaming daily was positively associated with central obesity (OR=2.12, p≤0.05) but not after adjustment for MVPA. Results further demonstrate the importance of reducing overall ST to maintain healthy weight status among UK youth.  相似文献