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1.
Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training.  相似文献   
2.
This study examines the representations of nanoscale science and technology in written popular media from 1986 to 1999. Nanoscale science is an emergent field that examines the principles of matter at a molecular level. This article presents the representations through which nanoscale science and technology was initially introduced to the public. Written popular media influences the ways stakeholder groups perceive, support, and fund science and technology. From 1986 to 1999 this field was introduced to the general public through articles in newspapers, magazines, and other general interest publications. During this period, nanoscale science and technology had a fragmented public image as proponents of various representations of the field competed for legitimacy. The study demonstrates that the emergence of nanoscience and technology in the popular media occurred as a competitive and transitional social-rhetorical process in which the new emerged within existing and established understandings of science but was mediated by biographical and other social accounts of the research.  相似文献   
3.
A motor skills assessment could be helpful in talent development by estimating essential perceptuo-motor skills of young players, which are considered requisite to develop excellent technical and tactical qualities. The Netherlands Table Tennis Association uses a motor skills assessment in their talent development programme consisting of eight items measuring perceptuo-motor skills specific to table tennis under varying conditions. This study aimed to investigate this assessment regarding its reproducibility, internal consistency, underlying dimensions and concurrent validity in 113 young table tennis players (6–10 years). Intraclass correlation coefficients of six test items met the criteria of 0.7 with coefficients of variation between 3% and 8%. Cronbach’s alpha valued 0.853 for internal consistency. The principal components analysis distinguished two conceptually meaningful factors: “ball control” and “gross motor function.” Concurrent validity analyses demonstrated moderate associations between the motor skills assessment’s results and national ranking; boys r = ?0.53 (< 0.001) and girls r = ?0.45 (= 0.015). In conclusion, this evaluation demonstrated six test items with acceptable reproducibility, good internal consistency and good prospects for validity. Two test items need revision to upgrade reproducibility. Since the motor skills assessment seems to be a reproducible, objective part of a talent development programme, more longitudinal studies are required to investigate its predictive validity.  相似文献   
4.
Peer review is a cornerstone of scientific publication, and consequently, predatory journals are feared to be a threat to the credibility of science as they perform no or low‐quality peer review. The question of why researchers decide to publish in a questionable journal remains relatively unexplored. This paper provides an overview of the existing literature on why researchers decide to publish papers in questionable journals, specifically whether or not they search for a low‐barrier way to getting published while being aware that the chosen journal probably does not adhere to acceptable academic standards. The choice of a publication outlet can be seen as a submission tree that consists of various incentives, and explaining why authors publish in deceptive journals may thus consist of a combination of awareness and motivational factors. Awareness and motivation of diligent authors is very different from that of unethical authors. Unethical authors may use a lack of awareness to excuse their actions, but they may actively search for a low‐barrier way to getting published. As there are different types of authors who publish in deceptive journals, we need different approaches to solve the problem.  相似文献   
5.
In small businesses with no employees, learning environments have a low learning readiness. Consequently, learners need to rely on their own agency to shape their learning experiences. Results from a study of agricultural entrepreneurs indicated that the components of motivation and self-regulated learning strategies shape learner's agency and explain learning environment configuration in small businesses with no employees. Configuration of the learning environment was found to be a weak determinant of the learning performance of these learners. However, results showed that prior performance of learners in small businesses with no employees dictates how their agency operates and what learning effect is achieved; higher prior performance results in higher learning effects. We conclude that mechanisms that underlie learning in traditional learning environments work similarly in learning environments in small businesses with no employees.  相似文献   
6.
ABSTRACT

Differences and similarities between table tennis and other racquet sports exist, but are not well documented in the literature, in spite of the relevance for talent identification. In this study we aimed at identifying the key characteristics of table tennis in comparison with tennis and badminton based upon a survey in coaches. A total of 177 licensed coaches from all across the world and with diverse professional backgrounds completed a survey on anthropometric measures, physical performance, and motor coordination skills. On a scale from 1 to 10, coaches indicated to what extent a talent characteristic was important for their sport. MANOVA identified key differences as well as similarities between all three racquet sports and a subsequent discriminant analysis allocated coaches correctly for table tennis, tennis, and badminton 81.01%, 55.6%, and 71.4% respectively. Our results show that table tennis and other racquet sport coaches are well aware of differences between the racquet sports and also the importance and value of testing and assortment of skill components. These findings can assist coaches in future talent orientation and transfer in racquet sports.  相似文献   
7.
For a valid determination of a rower’s mechanical power output, the anterior–posterior (AP) acceleration of a rower’s centre of mass (CoM) is required. The current study was designed to evaluate the accuracy of the determination of this acceleration using a full-body inertial measurement units (IMUs) suit in combination with a mass distribution model. Three methods were evaluated. In the first two methods, IMU data were combined with either a subject-specific mass distribution or a standard mass distribution model for athletes. In the third method, a rower’s AP CoM acceleration was estimated using a single IMU placed at the pelvis.

Experienced rowers rowed on an ergometer that was placed on two force plates, while wearing a full-body IMUs suit. Correspondence values between AP CoM acceleration based on IMU data (the three methods) and AP CoM acceleration obtained from force plate data (reference) were calculated. Good correspondence was found between the reference AP CoM acceleration and the AP CoM accelerations determined using IMU data in combination with the subject-specific mass model and the standard mass model (intraclass correlation coefficients [ICC] >?0.988 and normalized root mean square errors [nRMSE]?3.81%). Correspondence was lower for the AP CoM accelerations determined using a single pelvis IMU (0.877?Based on these results, we recommend determining a rower’s AP CoM acceleration using IMUs in combination with the standard mass model. Finally, we conclude that accurate determination of a rower’s AP CoM acceleration is not possible on the basis of the pelvis acceleration only.  相似文献   
8.
The greatest number of open access journals (OAJs) is found in the sciences and their influence is growing. However, there are only a few studies on the acceptance and thereby integration of these OAJs in the scholarly communication system. Even fewer studies provide insight into the differences across disciplines. This study is an analysis of the citing behaviour in journals within three science fields: biology, mathematics, and pharmacy and pharmacology. It is a statistical analysis of OAJs as well as non-OAJs including both the citing and cited side of the journal to journal citations. The multivariate linear regression reveals many similarities in citing behaviour across fields and media. But it also points to great differences in the integration of OAJs. The integration of OAJs in the scholarly communication system varies considerably across fields. The implications for bibliometric research are discussed.  相似文献   
9.
Objective:A growing volume of studies address methods for performing systematic reviews of qualitative studies. One such methodological aspect is the conceptual framework used to structure the review question and plan the search strategy for locating relevant studies. The purpose of this case study was to evaluate the retrieval potential of each element of conceptual frameworks in qualitative systematic reviews in the health sciences.Methods:The presence of elements from conceptual frameworks in publication titles, abstracts, and controlled vocabulary in CINAHL and PubMed was analyzed using a set of qualitative reviews and their included studies as a gold standard. Using a sample of 101 publications, we determined whether particular publications could be retrieved if a specific element from the conceptual framework was used in the search strategy.Results:We found that the relative recall of conceptual framework elements varied considerably, with higher recall for patient/population (99%) and research type (97%) and lower recall for intervention/phenomenon of interest (74%), outcome (79%), and context (61%).Conclusion:The use of patient/population and research type elements had high relative recall for qualitative studies. However, other elements should be used with great care due to lower relative recall.  相似文献   
10.
The paper introduces a new journal impact measure called The Reference Return Ratio (3R). Unlike the traditional Journal Impact Factor (JIF), which is based on calculations of publications and citations, the new measure is based on calculations of bibliographic investments (references) and returns (citations). A comparative study of the two measures shows a strong relationship between the 3R and the JIF. Yet, the 3R appears to correct for citation habits, citation dynamics, and composition of document types – problems that typically are raised against the JIF. In addition, contrary to traditional impact measures, the 3R cannot be manipulated ad infinitum through journal self-citations.  相似文献   
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