Is microrheometry affected by channel deformation?     

Francesco Del Giudice  Francesco Greco  Paolo Antonio Netti  Pier Luca Maffettone 《Biomicrofluidics》2016,10(4)

Microrheometry is very important for exploring rheological behaviours of several systems when conventional techniques fail. Microrheometrical measurements are usually carried out in microfluidic devices made of Poly(dimethylsiloxane) (PDMS). Although PDMS is a very cheap material, it is also very easy to deform. In particular, a liquid flowing in a PDMS device, in some circumstances, can effectively deform the microchannel, thus altering the flow conditions. The measure of the fluid relaxation time might be performed through viscoelasticity induced particle migration in microfluidics devices. If the channel walls are deformed by the flow, the resulting measured value of the relaxation time could be not reliable. In this work, we study the effect of channel deformation on particle migration in square-shaped microchannel. Experiments are carried out in several PolyEthylene Oxyde solutions flowing in two devices made of PDMS and Poly(methylmethacrylate) (PMMA). The relevance of wall rigidity on particle migration is investigated, and the corresponding importance of wall rigidity on the determination of the relaxation time of the suspending liquid is examined.  相似文献   

Analysis of doping control test results in individual and team sports from 2003 to 2015     

Millan Aguilar-Navarro  Jesus Munoz-Guerra  Maria del Mar Plara  Juan Del Cosoa 《运动与健康科学(英文)》2020,9(2):160-169

Background:Determining the prevalence of doping in sport might be useful for anti-doping authorities to gauge the effectiveness of anti-doping policies implemented to prevent positive attitudes toward doping.Using questionnaires and personal interviews,previous investigations have found that the prevalence of doping might be different among different sports disciplines;however,there is no sport-specific information about the proportion of adverse and atypical findings(AAF) in samples used for doping control.The aim of the present investigation was to assess the differences in the frequency of adverse analytical and atypical findings among sports using the data made available by the World Anti-Doping Agency.Methods:The data included in this investigation were gathered from the Testing Figures Reports made available annually from 2003 to 2015 by the World Anti-Doping Agency.These Testing Figures Reports include information about the number of samples analyzed,the number of AAFs reported,and the most commonly found drugs in the urine and blood samples analyzed.A total of 1,347,213 samples were analyzed from the individual sports selected for this investigation,and 698,371 samples were analyzed for disciplines catalogued as team sports.Results:In individual sports,the highest proportions of AAF were 3.3%±1.0% in cycling,3.0%±0.6% in weightlifting,and 2.9%±0.6% in boxing.In team sports,the highest proportions of AAF were 2.2%±0.5% in ice hockey,2.0%±0.5% in rugby,and 2.0%±0.5% in basketball.Gymnastics and skating had the lowest proportions at(≤1.0%) for individual sports,and field hockey,volleyball and football had the lowest proportions for team sports(≤1.4%).Conclusion:As suggested by the analysis,the incidence of AAF was not uniform across all sports disciplines,with the different proportions pointing to an uneven use of banned substances depending on the sport.This information might be useful for increasing the strength and efficacy of anti-doping policies in those sports with the highest prevalence in the use of banned substances.  相似文献   

Effects of a nonlinear pedagogy intervention programme on the emergent tactical behaviours of youth footballers     

Alba Práxedes  Fernando Del Villar Álvarez  Alberto Moreno  Alexander Gil-Arias  Keith Davids 《Physical Education & Sport Pedagogy》2019,24(4):332-343

Purpose: This study analysed the effects of a training intervention programme using principles of Non-Linear Pedagogy (NLP) on the decision making (DM) and performance behaviours (P) of youth footballers.

Method: 19 footballers (U12 yrs) participated in 14 training sessions, spread over three phases: Pre-intervention, Intervention, Retention. The intervention was based on Small-Sided and Conditioned Games. We assessed progress during the intervention phase at two different points: intermediate and final. The GPET instrument was used to analyse the DM and P during the completion of 3208 passes in the intervention.

Results: Results shown significant improvements in the DM and P after the intermediate and final points of the acquisition phase. Moreover, significantly higher values were also obtained in both variables in the retention, compared to the pre-intervention phase.

Conclusion: Results indicated that the NLP intervention programme was effective in improving both aspects of team games performance in youth players, with effects consolidated over time.  相似文献   

Effects of pitch spatial references on players’ positioning and physical performances during football small-sided games     

Diogo Coutinho  Bruno Gonçalves  Bruno Travassos  Eduardo Abade  Del P. Wong  Jaime Sampaio 《Journal of sports sciences》2019,37(7):741-747

The aim of this study was to identify the effects of adding spatial references during football small-sided games in youth players’ tactical and physical performance. Twelve under-15 players performed a Gk+ 6v6+ Gk game under two playing conditions: (i) without spatial references (CONTROL condition); (ii) with spatial references, by dividing equally the pitch into three corridors and three sectors (experimental situation, LINES). Players’ positional data was used to compute time-motion and tactical-related variables. The results revealed that performance under LINES situation increased the regularity in the zones occupied (~14%, Cohen’s d: 0.5; ±0.3; p = 0.003) and in the distance between teammates’ dyads (~19%, 0.9; ±0.2; p < 0.001). Oppositely, LINES condition decreased the longitudinal synchronization of players’ displacements (0.4; ±0.2; p = 0.002), players’ average speed (0.5; ±0.3; p = 0.002) and distance covered at lower (0.9; ±0.3; p < 0.001) and moderate speed (0.5; ±0.3; p < 0.001). Adding spatial references seems to promote a more structured pattern of play and increase positional regularity. However, coaches should be aware that this constraint may decrease the synchronization between players. Overall, these findings may be generalized to most invasion team sports.  相似文献   

Higher Education Access and Choice for Latino Students: Critical Findings and Theoretical Perspectives     

José Reyes Del Real Viramontes 《Journal of Latinos & Education》2018,17(3):290-291

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Search for autonomy in motor task learning in physical education university students     

Juan Antonio Moreno Murcia  José Antonio Vera Lacárcel  Fernando Del Villar Álvarez 《European Journal of Psychology of Education - EJPE》2010,25(1):37-47

The study focused on discovering the influence that an autonomous motor task learning programme had on the improvement of perceived competence, intrinsic regulation, incremental belief and motivational orientations. The study was performed with two groups of participants (n = 22 and n = 20) aged between 19 and 35 years. The instruments used were the incremental factor of the Conceptions of the Nature of Athletic Ability Questionnaire (CNAAQ-2), the Goal Orientation in Exercise Scale (GOES), the intrinsic regulation factor of the Behavioural Regulation in Exercise Questionnaire (BREQ-2), the perceived autonomy factor of the autonomy measurement scale (EMA) and the perceived competence factor of the Motives for Physical Activity Measure Revised Scale (MPAM-R). The questionnaires were handed out over 3 months in a weekly session with pre-test and post-test. The results showed that the use of an autonomy-based teaching programme increased perceived competence, intrinsic motivation, incremental ability belief and task-involving motivational orientation.  相似文献   

Heart rate recovery after aerobic and anaerobic tests: is there an influence of anaerobic speed reserve?     

Sebastián Del Rosso  Fabio Y. Nakamura 《Journal of sports sciences》2017,35(9):820-827

The present study assessed if differences in the metabolic profile, inferred from the anaerobic speed reserve (ASR), would influence the dynamics of heart rate recovery (HRR) after two modes of exercise. Thirty-nine physical education students (14 females and 25 males) volunteered for this study. Participants carried out three separate testing sessions to assess maximal sprinting speed (MSS, 1st session), repeated sprint ability (RSA, 2nd session) and maximal aerobic speed (MAS) using the Université of Montreal Track Test (UMTT, 3rd session). ASR was defined as the difference between MSS and MAS. Heart rate was continuously registered throughout the tests and during the 5-min post-test recovery. To evaluate the influence of ASR on post-exercise, HRR comparisons between ASR-based groups [high ASR vs. low ASR] and sex groups (males vs. females) were performed. Significant differences (P < 0.05) were found between high ASR and low ASR groups of the same sex for indices of relative HRR after the RSA and UMTT. In addition, after the RSA test, males from the high ASR group had a significantly slower HRR kinetics compared with the males of the low ASR (P < 0.05) and the females of high ASR (P < 0.05); whereas females of the high ASR groups had a faster HRR kinetics compared with the females of low ASR group (P < 0.05). Our results showed that in males, post-exercise HRR could be related to the ASR, whereas in females, the influence of ASR is less clear.  相似文献   

Neuroanatomy,the Achille’s Heel of Medical Students. A Systematic Analysis of Educational Strategies for the Teaching of Neuroanatomy     

Maria Alessandra Sotgiu  Vittorio Mazzarello  Pasquale Bandiera  Roberto Madeddu  Andrea Montella  Bernard Moxham 《Anatomical sciences education》2020,13(1):107-116

Neuroanatomy has been deemed crucial for clinical neurosciences. It has been one of the most challenging parts of the anatomical curriculum and is one of the causes of “neurophobia,” whose main implication is a negative influence on the choice of neurology in the near future. In the last decades, several educational strategies have been identified to improve the skills of students and to promote a deep learning. The aim of this study was to systematically review the literature to identify the most effective method/s to teach human neuroanatomy. The search was restricted to publications written in English language and to articles describing teaching tools in undergraduate medical courses from January 2006 through December 2017. The primary outcome was the observation of improvement of anatomical knowledge in undergraduate medical students. Secondary outcomes were the amelioration of long-term retention knowledge and the grade of satisfaction of students. Among 18 selected studies, 44.4% have used three-dimensional (3D) teaching tools, 16.6% near peer teaching tool, 5.55% flipped classroom tool, 5.55% applied neuroanatomy elective course, 5.55% equivalence-based instruction-rote learning, 5.55% mobile augmented reality, 5.55% inquiry-based clinical case, 5.55% cadaver dissection, and 5.55% Twitter. The high in-between study heterogeneity was the main issue to identify the most helpful teaching tool to improve neuroanatomical knowledge among medical students. Data from this study suggest that a combination of multiple pedagogical resources seems to be the more advantageous for teaching neuroanatomy.  相似文献   

关注CEO三分之一的执行总裁寻求新技能     

Del Jones 《海外英语》2006,(3):3

2006年,大公司的执行总裁将准备干点什么呢?答案是学习新技能和与家人欢度更多时光。  相似文献   

Disciplinary variation in preparation for the academic dean role     

Marietta Del Favero 《高等教育研究与发展》2006,25(3):277-292

This empirical study examined a sample of 210 academic deans in research and doctoral institutions in the United States to investigate the relationship between academic discipline and the preparation of deans for their leadership role. Respondents reported relying on experience in past administrative posts and past relationships with faculty leaders as the most highly valued approaches to learning what the deans’ job entails. Findings suggest that how deans understand their role is very much related to the unique experiences they have accumulated as a faculty member. Despite the low reliance overall on trial‐and‐error as a learning approach, deans in pure fields reported relying more on trial‐and‐error than deans from applied fields. This finding suggests that academic discipline cannot be discounted in considering the preparation of faculty for leadership roles.  相似文献