Relationship between split-step timing and leg stiffness in world-class tennis players when returning fast serves

ABSTRACT

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available. In Experiment 2, the neuromechanical capabilities (leg stiffness and vertical jump performance) of a group of world-class players and three groups of less-skilled tennis players were examined. The results showed an increase in leg stiffness with an increase in the level of expertise. A cross-experiment analysis in world-class male players (ATP/ITF, n = 10) revealed that the timing of initial foot movement was significantly correlated with the leg stiffness (r² = 0.54), with later lateral step after the serve in the players who had higher stiffness. The findings support the hypothesis that world-class tennis players adapt perceptual-motor control on the basis of their neuromechanical capabilities and maximise the time before initiating their interceptive action to rely on more reliable information.     

Effects of plyometric jump training on the physical fitness of young male soccer players: Modulation of response by inter-set recovery interval and maturation status

ABSTRACT

The effects of plyometric jump training on the physical fitness of male youth (age = 10–17 years) soccer players was examined in relation to inter-set recovery intervals and the maturity of the players in a single-blind, randomized-and controlled crossover trial. Jumping tests and kicking velocities were measured before (T₀), after a 6 week control period (T₁), after 6 weeks of plyometrics (T₂), after 6 weeks of wash-out (T₃), and after a further 6 weeks of plyometrics (T₄). Subjects were divided into pre- and post- peak-height-velocity (PHV) groups, and were randomly assigned to 30 s or 120 s inter-set intervals during periods T₂ and T₄. Any changes in jumping and maximum kicking velocities during T₁ and T_3, had trivial effect sizes (0.01–0.15), but small to moderate improvements (effect size = 0.20–0.99) were observed in both groups during T₂ and T₄. Gains in pre-PHV players were similar for the two inter-set intervals, but gains in post-PHV players were greater (p < 0.05) with an inter-set recovery of 120 s than with a 30 s recovery. We conclude that plyometric jump training improves the physical fitness of adolescents, irrespective of their maturity, but that in older individuals gains are greater with a longer inter-set recovery interval.     

Promotion and Knowledge of Online Patent Literature Search to Enhance Scientific Output in Tanzania: Case of Two Universities in Zanzibar

Abstract

This study examines the promotion and knowledge of online patent literature search among students, librarians, and instructors to enhance university scientific output in Zanzibar. The study was guided by four key questions: What is the level of awareness of students, instructors and library staff about patent documents as source of information? To what extent do students and instructors access online patent databases? What is the library experience in training students about online patent literature searching?, and what are the challenges facing library and instructors in promoting patent literature search? The study used survey approach whereby questionnaire and interview were used to collect data. The recent literatures regarding online patent literature searching were also critically reviewed. A survey was conducted at two Universities in Zanzibar namely the State University of Zanzibar and Zanzibar University, whereby 20 library staff, 10 instructors and 140 undergraduate students from the School of Computing and the Faculty of Engineering were involved in this study. The findings show that more than three quarters of respondents were either partially aware or not aware at all about the existence of free online patent databases. Likewise, the majority of students had no enough skills of patent literature searching. However, usually the library organizes training on general online literature searching skills but patent literature searching was not effectively taught and a big challenge observed in this study regarding promotion of patent literature searching is inadequate patent searching skills among library and instructors. Based on the findings, the study proposed several recommendations to rectify the existing problem.     

SRL-ESA-TextSum: A text summarization approach based on semantic role labeling and explicit semantic analysis

Automatic text summarization attempts to provide an effective solution to today’s unprecedented growth of textual data. This paper proposes an innovative graph-based text summarization framework for generic single and multi document summarization. The summarizer benefits from two well-established text semantic representation techniques; Semantic Role Labelling (SRL) and Explicit Semantic Analysis (ESA) as well as the constantly evolving collective human knowledge in Wikipedia. The SRL is used to achieve sentence semantic parsing whose word tokens are represented as a vector of weighted Wikipedia concepts using ESA method. The essence of the developed framework is to construct a unique concept graph representation underpinned by semantic role-based multi-node (under sentence level) vertices for summarization. We have empirically evaluated the summarization system using the standard publicly available dataset from Document Understanding Conference 2002 (DUC 2002). Experimental results indicate that the proposed summarizer outperforms all state-of-the-art related comparators in the single document summarization based on the ROUGE-1 and ROUGE-2 measures, while also ranking second in the ROUGE-1 and ROUGE-SU4 scores for the multi-document summarization. On the other hand, the testing also demonstrates the scalability of the system, i.e., varying the evaluation data size is shown to have little impact on the summarizer performance, particularly for the single document summarization task. In a nutshell, the findings demonstrate the power of the role-based and vectorial semantic representation when combined with the crowd-sourced knowledge base in Wikipedia.     

Use of on-line databases by faculty members and research scholars of Jawaharlal Nehru University (JNU) and Jamia Millia Islamia (JMI), New Delhi (India): A survey

The study is focused on finding out the level of use of on-line databases by faculty members and research scholars of the Jawaharlal Nehru University (JNU) and Jamia Millia Islamia (JMI), Delhi (India). Both are Central Universities and are funded by the University Grants Commission (UGC). A well-structured questionnaire was administered to faculty members and research scholars of the JNU and JMI to collect data regarding the use of on-line database. The survey reveals that all of the faculty members and research scholars are aware of the availability of on-line databases and largely use them for reference purposes in their research work and studies. The degree of usefulness and utilization of on-line databases is high among the universities' faculty members and research scholars. The survey further reveals that the respondents from both universities are aware of the search options for accessing on-line databases. It is also found that a large number of respondents of JNU and JMI are using field searching and Boolean operators to access information from on-line databases.     

代表UNESCO向"UNESCO信息素养培训师培训班(武汉)"致欢迎词

女士们,先生们,早上好! 感谢你们今天的热情欢迎. 今天我很荣幸地来到武汉,这个地处中国中部的政治、经济、文化和教育都市.武汉的生机与活力也反映了过去20年中国的空前发展,在此高速增长之下,我期待着在不久的将来看到更大的进步.     

Gender and behavioural differences in Kuwait primary schools

Previous studies have found significant differences between the classroom behaviour of boys and girls. Most are within a single broad cultural context and little work has been done within an Arabic/Kuwaiti one. The main aim was to investigate the differences in behaviour between boys and girls in Kuwait primary schools. Data were collected that provided comparisons across questionnaires between parent and teacher returns for over 430 students. Separate teacher observations of students (n = 671) and classroom researcher observations were also obtained. Significant differences were found across the scales, indicating higher levels of externalising misbehaviour among boys than girls. A comparison with three studies conducted in other cultural contexts using the same strengths and difficulties instrument as used in this study found similarities and differences in results between the behaviour of boys and girls.     

HealthCyberMap: a semantic visual browser of medical Internet resources based on clinical codes and the human body metaphor

OBJECTIVES: HealthCyberMap (HCM-http://healthcybermap.semanticweb.org) is a web-based service for healthcare professionals and librarians, patients and the public in general that aims at mapping parts of the health information resources in cyberspace in novel ways to improve their retrieval and navigation. METHODS AND SERVICE DESCRIPTION: HCM adopts a clinical metadata framework built upon a clinical coding ontology for the semantic indexing, classification and browsing of Internet health information resources. A resource metadata base holds information about selected resources. HCM then uses GIS (Geographic Information Systems) spatialization methods to generate interactive navigational cybermaps from the metadata base. These visual cybermaps are based on familiar medical metaphors. CONCLUSIONS: HCM cybermaps can be considered as semantically spatialized, ontology-based browsing views of the underlying resource metadata base. Using a clinical coding scheme as a metric for spatialization ('semantic distance') is unique to HCM and is very much suited for the semantic categorization and navigation of Internet health information resources. Clinical codes ensure reliable and unambiguous topical indexing of these resources. HCM also introduces a useful form of cyberspatial analysis for the detection of topical coverage gaps in the resource metadata base using choropleth (shaded) maps of human body systems.     

Simulation of intermittent thermal compression processes using adsorption technology

This paper presents a dynamic model to simulate the adsorption-desorption processes associated with intermittent heat pump systems. This simulation plays an important role in sizing the adsorption systems for various types of applications in the design stage. A mathematical model that is based on the control volume approach was first developed and then discretized using the finite difference implicit scheme. The equations for the conservation of mass, momentum, and energy in the bed were derived for high-pressure and low-pressure segments, including the adsorbate (refrigerant), the adsorbent (Linde 13X), and the vessel wall. A pseudo-homogeneous model for the compression system was adopted. The numerical results that describe the adsorption-desorption history were obtained. It was found that the amount of the refrigerant recovered in the desorption process at the end of the cyclic operation is smaller than the amount adsorbed during the adsorption process. This indicates that the time for the regeneration process should be longer than the time for the adsorption process in order to raise the sieve temperature. In order to compare the simulated results with experimental data, numerical values for the heat transfer coefficients were theoretically evaluated. To assure the stability of the simulated results, the incremental time of system operation is kept equal or less than the value obtained from the minimum stability requirement. The simulated results of the temperature distribution history during system operation are in good agreement with the conducted experimental results, which led to the conclusion that the model can be used as an effective tool during the design stage and for the system development.     

New approaches to facilitate learning from youth: Exploring the use of Photovoice in identifying local watershed issues

In urbanized areas, incorporating residents’ concerns and priorities into the stormwater management debate has focused on adults rather than youth. This study used Photovoice, a tool that includes photographs taken by youth, to uncover youth concerns and perceptions about their local watersheds. This study consisted of a comparative study of two watersheds. Twenty students produced 468 photographs. Although both groups of students shared common themes regarding stormwater and pollution, these themes differed in level of concerns over local environmental issues, sentiments with particular features in their local watersheds, and concerns about local watersheds. From a methodological perspective, Photovoice provided a way of capturing youth perspectives and to identify important features and issues in their respective local watersheds.