Sports injuries in an America's Cup yachting crew: A 4-year epidemiological study covering the 2007 challenge

Abstract

The aim of this study was to describe the injuries sustained by an America's Cup crew during eight preparatory competitions of the 32nd America's Cup 2007 and the Louis Vuitton Cup (from October 2004 to June 2007). The anatomical location, type of injury, and mechanism of injury were recorded. The injuries were categorized based on each sailor's position on the boat according to three intensities of physical demands. The injury rates per sailor and per 1000 h of competition were determined. In total, 90 injuries were registered. The overall incidence was 10 injuries per 1000 competition hours. Overuse injuries accounted for 76.6% of all lesions. The most common anatomical location of injuries was the upper limb (36.6%), followed by the upper dorsal and cervical spine (34.4%). Frequency of injury was related to the sailor's position on the boat, being higher in the group with more demanding activities (grinder, bowman, and mastman). Most injuries (67%) were sustained by this group of sailors. The most common injuries in this group were muscle contractures of the quadratus lumborum (11), trapezius (8), and rhomboid (7). There were eight cases of elbow epicondylitis, four cases of tendinopathy of the supraspinous tendon, and three cases of tendinopathy of the biceps brachii. An America's Cup yachting crew is exposed to a high risk of overuse injuries, especially those sailors whose boat position involves high-intensity activity.     

Translating Key Competences into the School Curriculum: lessons from the Polish experience

Over the last 20 years, Poland has gone through a major transition process in which the challenges for education in terms of new approaches to learning and teaching have been compounded by broader changes such as the democratisation of structures and processes and the major economic and social changes. This article is a case study that examines the early stages of significant shifts in the learning and teaching process, the stepped approach that was taken and the different international influences. It was decided to focus on the top-down, policy level actions in order to trace how influences have shaped current policy on outcomes-based approaches and key competences, which are increasingly implemented in schools today. The Polish education and training system has been through a complex series of reforms, many simultaneously. The introduction of outcome-based approaches and key competences is part of much broader reforms that have affected mindsets and attitudes by having addressed the structure of the system (e.g. the length of compulsory education), school governance, the roles of principals and teachers, teacher training, etc. Parents' expectations have evolved and students are growing up in a much more connected environment with Internet and social networks and an exponential development of access to ICT and the need for digital competences and a range of key competences for lifelong learning and work (Gordon et al., 2009). Although change has taken place at all levels and in all sub-sectors of the system, this article focuses on general education in primary and secondary schools.     

Choosing the Future: Economic Preferences for Higher Education Using Discrete Choice Experiment Method

Research in Higher Education - This study illustrates how respondents’ stated choices (the discrete choice experiment method) combined with the random utility framework can be used to model...     

Bipolar queries in textual information retrieval: A new perspective

A new concept of a bipolar query against collections of textual documents, i.e. in the context of information retrieval (IR), is introduced using recent developments in bipolar information modeling and bipolar database queries. Specifically, a particular approach to bipolar queries with an explicit “and possibly” type of an aggregation operator is used. An effective and efficient processing of such bipolar queries using standard IR data structures is briefly discussed. The bipolar queries proposed combine a flexibility provided by fuzzy logic with a more sophisticated representation of user preferences and intentions. This combination can make the search of vast resources of textual document, notably those available via the Internet, more intelligent.     

Discrete time sliding mode controllers with relative degree one and two switching variables

In this paper, a new reaching law based sliding mode control strategy for discrete time systems is introduced. Contrary to most existing approaches, the new strategy uses a sliding variable with relative degree two. It is demonstrated that the new reaching law drives the sliding variable to a narrower quasi-sliding mode band than its relative degree one equivalent, while simultaneously ensuring the desired dynamic properties of the system. Furthermore, it is shown that the smaller quasi-sliding mode band width is reflected in reduced magnitude of all state variables in the sliding mode.     

Multilevel information system— Towards more flexible information retrieval systems

The Multilevel Information System (MLIS), extension of typical Information Retrieval System towards more complete data processing, is discussed. MLIS integrates functions typical for data base management systems and retrieval-oriented systems. Several levels of data accessing are provided, each level developed for a different class of users. End-user level is based on simple query language, trained user level on a relational model, and application programmer level on a Data Manipulation Language nested in high level programming language. The last two levels are discussed in detail.     

Inverse dynamics control in terms of unnormalized quasi-velocities

In this paper a proposition of inverse dynamics control for a manipulator using the unnormalized quasi-velocities (UQV) is presented. These quasi-velocities introduced by Jain and Rodriguez (IEEE Trans. Robotics Automat,16, 2000, 517; 11, 1995, 571) are used here to show some performance obtained from the controller. It is shown that for a two d.o.f. planar manipulator one can assume UQV which are integrable with respect to time. The introduced controller in terms of UQV is exponentially convergent. As a consequence of using UQV inverse dynamics control, one can notice some interesting properties in comparison with the classical controller. Additionally, some geometrical interpretation based on Riemannian geometry is given.     

The effect of peer group stability on achievements: Evidence from Poland

This article reports on a study using data from nation-wide standardised examinations in Poland. We analysed the extent to which grade 9 student achievements have depended on the stability of their peer group over the course of middle school. We controlled for the fixed effects of schools attended by the students, as well as for individual achievements prior to middle school enrolment. To mitigate the risk for endogeneity, analysis was informed by a consideration of the fact that middle schools operate in different institutional relations with nearby primary schools. This also allowed us to distinguish between the effect related to peer group stability and the one connected to the stability of the learning environment in general. The results of our analysis show that instability significantly reduces students' expected performance in mathematics and science. The impact of peer group stability on test achievements varies strongly across the student ability distribution. Very low-performing students and top performers were most affected. The average students were largely unaffected. One category of students that seems to benefit from the change when moving to middle school are students from very competitive primary schools who have average skills.