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.     

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.     

Finite frequency range robust iterative learning control of linear discrete system with multiple time-delays

This paper uses repetitive process stability theory to design robust iterative learning control law for linear discrete systems with multiple time-delays and polytopic uncertainty. Both dynamic and static forms of the control law are considered and used when designing robust iterative learning control schemes. Also, based on the generalized Kalman-Yakubovich-Popov Lemma, the proposed design procedures a required frequency attenuation over a finite frequency range and the monotonic trial-to-trial error convergence. Moreover, linear matrix inequality techniques are applied to formulate the convergence conditions and to obtain formulas for the control law designs. Finally, an illustrative numerical simulation example is given and concludes the paper.     

The relationship between meeting of recommendations on physical activity for health and perceived work ability among white-collar workers

Objective: The aim of this study was to evaluate the association between meeting recommendations on physical activity for health in leisure-time and the ability to work among Polish white-collar workers. Methods: The study used a cross-sectional design with a convenience sample of 360 white-collar workers. Participants recorded 7-day physical activity logs, including form, duration and intensity of leisure-time physical activities. The results were compared to health recommendations. A standardized Work Ability Index (WAI) questionnaire was used in assessing the ability to work. Results: Participants who met health recommendations achieved higher scores of the WAI (mean score?=?41.93) in comparison to those who were not sufficiently physically active (mean score?=?39.35) (p?Conclusions: Meeting leisure-time physical activity recommendations (especially the criterion of vigorous physical activity) is significantly related to higher self-assessed ability to work among white-collar workers.     

Nonlinear trajectory tracking controller for a class of robotic vehicles

A global state feedback tracking controller for a class of vehicles, namely marine vehicles, hovercrafts and indoor airships is considered in this paper. The control algorithm uses a velocity transformation of the vehicle equations of motion. It is shown that this algorithm is suitable for control of fully actuated systems and leads to fast response. This property arises from the fact that the dynamical couplings in the vehicle are taken into account in the control gain matrix. A Lyapunov-like function is proposed for the stability analysis of the system under the controller. The algorithms robustness issue is considered too. Numerical simulations are given to illustrate effectiveness of the approach.     

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.     

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.     

Managing Social Media Use: Whither Social Media Guidelines in News Organizations?

Fears exist that social media use by news media and journalists may affect basic journalistic tenets such as objectivity, gatekeeping, and transparency. As a result, more and more news media organizations are issuing guidelines to manage employee use of social media. In this article we discuss the complex relationship of a selection of market-leading news media organizations with prescribed use of social media. Applying content analysis to 12 existing social media guidelines, we elaborate on the various types of rules linked with the basic principles of journalism. A key intention of this research is to provide insights for media management and journalism scholars to better understand the use of social media by journalists and the implementation of guidelines by media organizations. More practically, this article can aid media organizations who are shaping their own set of rules regarding use of social media by their staff.