The influence of pacing strategy on marathon world records

The aim of this study was to analyse the influence of the pacing strategy adopted by elite marathon runners when setting every marathon world record in the last 50 years. We divided former marathon record holders into two groups: classic athletes (record holders between 1967 and 1988) and contemporaneous athletes (record holders between 1988 and 2018). The total distance of the marathon was divided into 8 sections of 5?km and 1 last section of 2.195?km, and the relative average speed of each section was calculated individually. On average athletes were slightly faster in the first half-marathon than in the second one, where they slowed down progressively (ES?=?0.28, small effect). However, when comparing classic vs. contemporaneous athletes, we observed that classic athletes started significantly faster (p?相似文献   

Improved similarity-based modeling for the classification of rotating-machine failures

Similarity-based modeling (SBM) is a technique whereby the normal operation of a system is modeled in order to detect faults by analyzing their similarity to the normal system states. First proposed around two decades ago, SBM has been successfully used for fault detection in varied systems. In spite of this success, there is not much study performed in the literature regarding its design, that encompasses both similarity metrics and model training. This work aims at contributing with an in-depth study of SBM for fault detection considering these two design aspects. This is done in the context of proposing a novel system to identify rotating-machinery faults based on SBM, that is employed either as a standalone classifier or to generate features for a random forest classifier. New approaches for training the model and new similarity metrics are investigated. Experimental results are shown for the recently developed Machinery Fault Database (MaFaulDa) that has an extensive set of sequences and fault types, and for the Case Western Reserve University (CWRU) bearing database. Results for both databases indicate that the proposed techniques increase the generalization power of the similarity model and of the associated classifier, achieving accuracies of 98.5% on MaFaulDa and 98.9% on CWRU database.     

Effects of bilateral and non-dominant practices on the lateral preference in judo matches

This study analysed the effects of bilateral and non-dominant practice on novice practitioners’ lateral preference for judo skills in a combat context (i.e., randori). Thirty sports sciences students (22 men and 8 women; mean age 19 ± 1 years) with right hand, foot, and counterclockwise rotation preferences were divided into 3 groups: bilateral (BG; n = 8), non-dominant (NDG; n = 11), and control (CG; n = 11). Participants received 8 weeks of training at a rate of 3 days per week. The NDG was trained to perform judo skills exclusive with their non-dominant side, while the BG performed every task symmetrically. Before and after training, participants were recorded during two 3-min randoris to obtain the percentage of their engagement in dominant side actions. Pretest percentages were 73.1 ± 19.9%, 77.8 ± 18.8%, and 68.9 ± 27.2% for BG, NDG, and CG, respectively. Post-test values were 75.0 ± 15.6%, 23.3 ± 27.9%, and 72.2.9 ± 20.4%, respectively. Significant differences were observed between NDG and each of the other groups after the training. Changes from pretest were only significant for NDG (P = 0.003). These results suggest that lateral preference among novice judo practitioners during randori can be modulated by the type of practice.     

The impact of exercise training on the lipid peroxidation metabolomic profile and respiratory infection risk in older adults

Aging is associated with oxidative stress that may increase susceptibility to respiratory infections (RIs). We aimed to assess the impact of exercise training on the risk of RIs in older adults and on a targeted metabolomic profile of stress oxidative lipid peroxidation-related metabolites. Methods: In an 8-month clinical trial, 38 participants over 60 years of age were allocated to an exercise group (EG), in which participants underwent 90-min training sessions three times/week(n?=?20), or a control group (CG), in which participants maintained daily physical activities(n?=?18). Daily respiratory symptoms and RIs number and severity were collected. Serum by-products were assessed by comprehensive two-dimensional gas chromatography coupled to mass spectrometry with time of flight analyzer. Serum metabolomic profiling comprised 76 metabolites (alcohols, aldehydes, alkanes, and ketones). Principal components analysis and ANOVA-simultaneous component analysis were used to evaluate the metabolomic profile change. Results: The odds ratio of RIs for the EG was 2.0 CI 95% [0.2;25]. The incidence of RIs was 47% [23;70] in the EG vs. 44%[12;77] in the CG. The metabolomic profiling showed that alkanes and aldehydes classes differed between the EG and the CG before and after intervention. A calibration model showed a relation between the metabolites from four main classes (ketones, alcohols, alkanes and aldehydes) and the prediction of the number of RIs. Conclusion: Moderate exercise training, in older adults, compared with no exercise in controls, did not show a difference in the risk of RIs. A pattern of lipid peroxidation was associated with the number of RIs.     

Controllability of Volterra-Fredholm type systems in Banach spaces

We show the results in Chalishajar [Controllability of mixed Volterra-Fredholm-type integro-differential systems in Banach space, J. Franklin Inst. 344(1) (2007) 12-21] and Chang and Chalishajar [Controllability of mixed Volterra-Fredholm type integro-differential systems in Banach space, J. Franklin Inst., doi:10.1016/j.jfranklin.2008.02.002] are only valid for ordinary differential control systems. As a result the examples provided cannot be recovered as applications of the abstract results.     

Cultural Differences in Maternal Beliefs and Behaviors: A Study of Middle-Class Anglo and Puerto Rican Mother-Infant Pairs in Four Everyday Situations

This study examines cultural patterning in situational variability in mother-infant interactions among middle-class Anglo and Puerto Rican mothers and their 12 to 15-month-old firstborn children. Forty mothers were interviewed regarding their long-term socialization goals and childrearing strategies, and videotaped interacting with their infants in four everyday settings: feeding, social play, teaching, and free play. Results suggest that: (1) Anglo mothers place greater emphasis on socialization goals and childrearing strategies consonant with a more individualistic orientation, whereas Puerto Rican mothers place greater focus on goals and strategies consistent with a more sociocentric orientation; (2) coherence was found between mothers' childrearing beliefs and practices, with Puerto Rican mothers more likely to directly structure their infants' behaviors; and (3) situational variability arose in mother-infant interactions, but this variability showed a cultural patterning consistent with mothers' long-term socialization goals and childrearing beliefs.     

Paraprofessionals use of group school-based instrumental mentoring: Examining process and preliminary outcomes

Many schools use paraprofessionals to implement and monitor interventions. Though paraprofessionals are cost-effective, many questions remain about the training and skills they need to implement a wide array of school-based interventions. In this study, we compare paraprofessionals' (i.e., undergraduates) implementation of the Group-Academic Mentoring Program for Education Development (Group-AMPED) to school psychology graduate students' implementation of Group-AMPED. Ten paraprofessionals and five school psychology graduate students provided approximately eight sessions of Group-AMPED to 35 sixth-grade students. Results indicated no significant differences between middle school students' engagement when groups were led by either school psychology graduate students or paraprofessionals. Similarly, self-reports of fidelity and supervisor postsession implementation confidence indicated no difference between paraprofessionals and graduate students' implementation of Group-AMPED. Follow-up measures indicated that mentors and proteges perceived Group-AMPED as feasible, acceptable, and understandable. Most importantly, middle school students participating in Group-AMPED had significantly higher second-semester grades in comparison to a small control group.     

Participation in the figured world of graffiti

This article is based on ethnographic work with two “crews” of young graffiti artists in southern Mexico City. The crews share certain characteristics with gangs or urban tribes, but more with “communities of practice”: they live in the “figured world” of graffiti, a community of practice at the local and global level. Through participation, including observation and the study of fanzines, group members learn the language, technical and social skills, and values of this figured world. Their reasons to paint and the topics they express are varied, but authentic expression is fundamental. Graffiti allows these young people to establish an interesting interplay of identities in the world of graffiti versus their ordinary lives.