Using accelerometry to quantify deceleration during a high-intensity soccer turning manoeuvre

Abstract

The mechanics of cutting movements have been investigated extensively, but few studies have considered the rapid deceleration phase prior to turning which has been linked to muscle damage. This study used accelerometry to examine the influence of turning intensity on the last three steps of a severe turn.

Ten soccer players performed 135° “V” cuts at five different intensities. Resultant decelerations were recorded from a trunk-mounted tri-axial accelerometer. Lower limb kinematics and ground reaction forces (GRF) from the pivot foot-ground contact (FGC) were also monitored.

Average peak trunk decelerations were larger at the two preceding steps (4.37 ± 0.12 g and 4.58 ± 0.11 g) compared to the PIVOT step (4.10 ± 0.09 g). Larger peak joint flexion angular velocities were observed at PRE step (ankle: 367 ± 192 deg.s^?1; knee 493 ± 252 deg.s^?1) compared to PIVOT step (ankle 255 ± 183 deg.s^?1; knee 377 ± 229 deg.s^?1). Turn intensity did not influence peak GRF at PIVOT step.

This study highlights the importance of steps prior to turning and their high-frequency loading characteristics. It is suggested that investigations of lower limb loading during turning should include this deceleration phase and not focus solely on pivot FGC.     

Accelerating the Development of Second-Order False Belief Reasoning: A Training Study With Different Feedback Methods

One-hundred-six 5-year-olds’ (M_age = 5;6; SD = 0.40) were trained with second-order false belief tasks in one of the following conditions: (a) feedback with explanation; (b) feedback without explanation; (c) no feedback; (d) active control. The results showed that there were significant improvements in children's scores from pretest to posttest in the three experimental conditions even when children's age, verbal abilities, or working memory scores were controlled for. The training effect was stable at a follow-up session 4 months after the pretest. Overall, our results suggest that 5-year-olds’ failures in second-order false belief tasks are due to lack of experience and that they can be helped over the threshold by exposure to many stories involving second-order false belief reasoning, including why questions.     

Does a perceptuomotor skills assessment have added value to detect talent for table tennis in primary school children?

ABSTRACT

Talent detection intends to support lifelong sports participation, reduce dropouts and stimulate sports at the elite level. For this purpose it is important to reveal the specific profile which directs children to the sports that connect to their strengths and preferences. This study evaluated a perceptuomotor skills assessment as part of talent detection for table tennis, a sport in which perceptuomotor skills are considered essential to cope with the difficult technical aspects. Primary school children (n = 121) and gifted young table tennis players (n = 146) were assessed using the Dutch perceptuomotor skills assessment measuring “ball control” and “gross motor function”. A discriminant function analysis confirmed the added value by identifying primary school children fitting the table tennis perceptuomotor profile of the young gifted table tennis players (28%). General linear model analyses for the assessment’s individual test items showed that the table tennis players outperformed their primary school peers on all “ball control” items (P < 0.001). In conclusion, the assessment appears to be of added value for talent detection in table tennis at this young age. Longitudinal studies need to reveal the predictive value for sports participation and elite sports.     

Governance Initiatives Creating a Demand-Driven E-Commerce Approach: The Case of Denmark

The Danish e-commerce strategy is a highly ambitious effort to become the world's leading IT nation. Instead of a production-led approach aimed at stimulating domestic hardware and software production, Denmark has pursued a demand-oriented approach focused on promoting the widespread adoption of e-commerce in the Danish society. The Danish government has developed a number of e-commerce initiatives via public-private sector partnerships--an approach we refer to as "governance." So far, it appears that Denmark has been successful in promoting business-to-business (B2B) e-commerce, with a number of Danish companies being global leaders in the use of B2B applications. On the other hand, Denmark has had less success in achieving widespread use of business-to-consumer (B2C) e-commerce. This article analyzes the Danish national environment for e-commerce, discusses four sets of governance initiatives aimed at the development of e-commerce, and analyzes the reasons for its success in B2B and relative failure in B2C adoption.     

Evaluation of a Multi-case Participatory Action Research Project: The Case of SOLINSA

Abstract

Purpose: Scholars agree that evaluation of participatory action research is inherently valuable; however there have been few attempts at evaluating across methods and across interventions because the perceived success of a method is affected by context, researcher skills and the aims of the participants. This paper describes the systematic evaluation of participatory action research with 17 European networks (LINSA) as part of a research project titled SOLINSA: Support of Learning and Innovation Networks for Sustainable Agriculture.

Methodology: Participatory action research was carried out over three years in collaboration with the 17 LINSA using a learning-oriented evaluation that was adapted to SOLINSA. The collaboration was evaluated using a structured evaluation instrument that was developed in the project.

Findings: The primary achievements of the interactions were based around enabling LINSA to reflect on their state and their practices. Joint reflection; facilitated by a member of the research team and in collaboration with the LINSA, stimulated internal engagement, enabled rethinking of the network's positioning, contributed to strategy development, and enabled creation of concrete outputs. Participation in the reflection process served to encourage commitment to the LINSA by individuals while improving relationships within the LINSA. Researchers and participants expressed that collaborative action research can be considered successful when both parties give and gain benefits, such as new knowledge or improved practical solutions.

Practical implications: Comparison of self-evaluation of different networks using a single tool enabled the identification of common factors that contribute to successful collaboration. Included in these common factors was the need to identify and build a working relationship with key partners based on mutual trust and commitment, and to gain a balance between guidance and listening, interactions and freedom, and positive and critical reflection: a fragile equilibrium that is difficult and time consuming to establish.

Originality: The adaptation of learning-oriented evaluation, by including a structure to allow comparison between the wide range of contexts, provides a useful instrument for evaluating participatory action research processes.     

Phenoxyethanol-Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

Embalming fixatives such as formaldehyde and phenol have been associated with occupational health hazards. While anatomists aim at replacing these chemicals, this seems presently unfeasible in particular for formaldehyde. Furthermore, fixation protocols usually require well-equipped facilities with highly experienced staff to achieve good fixation results in spite of only a minimal use of formaldehyde. Combining these aspects, a technique robust enough to be carried out by morticians is presented, resulting in durable tissues with minimal formaldehyde use. An embalming protocol involving phenoxyethanol was established, using concentrations of 7 and 1.5 Vol% of phenoxyethanol in the fixative and the conservation fluid, respectively. Visual, haptic, histological, and biomechanical properties and their perceived potential to positively influence student learning outcomes were compared to standard embalming techniques. The phenoxyethanol technique provides esthetic, durable, and odorless tissues. Bleaching is less pronounced compared to ethanol- or formaldehyde-based protocols. The tissues remain pliable following the phenoxyethanol-based embalming and can be used for biomechanical experiments to some extent. Phenoxyethanol-fixed tissues are well suited for undergraduate teaching with perceived positive learning outcomes and partly for postgraduate training. Phenoxyethanol tissues provide the option to obtain well-preserved histology samples, similar to those derived from formaldehyde. The provided protocol helps replace the use of phenol and formaldehyde for conservation purposes and minimizes the use of formaldehyde for the initial injection fixation. Phenoxyethanol-based embalming forms an effective alternative to standard embalming techniques for human cadavers. It is simple to use, allowing fixation procedures to be carried out in less sophisticated facilities with non-anatomy staff.     

A good hustle: the moral economy of market competition in adult webcam modeling

In this article, we examine how models working on Chaturbate, one of the world’s most popular adult webcam platforms, negotiate and make sense of the dynamic ways in which this platform configures their competitive environment. By combining different perspectives from the field of economic sociology, we demonstrate how competition on Chaturbate is shaped by various market devices whose strategic negotiation informs – and is informed by – the moral economy articulated on web forums where models gather to discuss their work experiences and market strategies. We first introduce Chaturbate and the ways in which it organizes market competition, surveying the environment models have to negotiate. We then zoom in on two controversial strategies for beating the competition, each of which upset the moral economy of Chaturbate’s model community. Subsequently, we turn to what models term ‘the hustle,’ which encompasses a number of competitive strategies and criteria judged to be fair and thus legitimate. The final part of our analysis considers the limitations of the hustle, as well as the meritocratic and entrepreneurial discourse that surround it, in light of what we identify as Chaturbate’s ‘manufactured uncertainty.’     

Demonstration of pelvic anatomy by modified midline transection that maintains intact internal pelvic organs

Gross dissection for demonstrating anatomy of the human pelvis has traditionally involved one of two approaches, each with advantages and disadvantages. Classic hemisection in the median plane through the pelvic ring transects the visceral organs but maintains two symmetric pelvic halves. An alternative paramedial transection compromises one side of the bony pelvis but leaves the internal organs intact. The authors propose a modified technique that combines advantages of both classical dissections. This novel approach involves dividing the pubic symphysis and sacrum in the median plane after shifting all internal organs to one side. The hemipelvis without internal organs is immediately available for further dissection of the lower limb. The hemipelvis with intact internal organs is ideal for showing the complex spatial relationships of the pelvic organs and vessels relative to the intact pelvic floor. Anat Sci Educ 3:254–260, 2010. © 2010 American Association of Anatomists.     

PBL:大学课程的改革与创新

本文阐述了PBL的基本概念、学习原理以及不同层面PBL课程改革需要考虑的因素。以技术、人文与社会课程(旨在提高工程师的社会责任感)为案例,分析了三种不同形式的教案设计:以传统授课为基础的教学设计、单门课程的PBL教学设计及交叉学科的PBL课程设计。最后得出结论:交叉学科的PBL方法是一种比传统授课模式更有效的课程设计,可以有效地提高和促进学生的认知学习、合作学习、内容掌握、自我满意程度及职业认同感等。