Task constraints

Newell (1985, 1986) identified the importance of interacting constraints on the emergent behaviours of learners or performers in sport as they assemble functional states of movement organisation in achieving task goals. Constraints, related to the person, task and environment, were defined as ‘boundaries or features that limit motion of the entity under consideration at any moment in time’ (Newell, 1986, p.347). Personal (or organismic) constraints include factors such as individual anthropometrics (height, weight, and limb lengths), fitness (e.g., strength, speed, aerobic capacity, and flexibility), mental skills (e.g. concentration, confidence, emotional control and motivation), perceptual and decisionmaking skills (e.g., recognising patterns of play, anticipation by reading the movements of opponents) and personality factors (e.g., risk taking or conservative behaviours). Newell (1986, p.350) distinguished between general environmental constraints, such as gravity, ambient temperature, natural light and altitude and task constraints, which are task specific and concerned with the goals of a specific activity. More recently, socio-cultural constraints (e.g., family support, cultural expectations and access to facilities) have also been considered as environmental constraints. Application of the constraints framework to the study of sport performance has led to task constraints being defined to include factors such as rules of games, equipment used, boundary playing areas and markings, nets and goals, the number of...

Delirium in the ICU : a review

AIM The aim of this paper was to review the current discourse in relation to intensive care unit (ICU) delirium. In particular, it will discuss the predisposing and contributory factors associated with delirium's development as well as effects of delirium on patients, staff and family members. BACKGROUND Critically ill patients are at greater risk of developing delirium and, with an ageing population and increased patient acuity permitted by medical advances, delirium is a growing problem in the ICU. However, there is a universal consensus that the definition of ICU delirium needs improvement to aid its recognition and to ensure both hypoalert-hypoactive and hyperalert-hyperactive variants are easily and readily identified. RELEVANCE TO CLINICAL PRACTICE The effects of ICU delirium have cost implications to the National Health Service in terms of prolonged ventilation and length of hospital stay. The causes of delirium can be readily classified as either predisposing or precipitating factors, which are organic in nature and commonly reversible. However, contributory factors also exist to exacerbate delirium and having an awareness of all these factors promises to aid prevention and expedite treatment. This will avoid or limit the host of adverse physiological and psychological consequences that delirium can provoke and directly enhance both patient and staff safety. CONCLUSIONS Routine screening of all patients in the ICU for the presence of delirium is crucial to its successful management. Nurses are on the front line to detect, manage and even prevent delirium.

Challenges of recruiting hospice patients with advanced cancer to research : reflections on a delirium screening study

Introduction Delirium research in palliative care, particularly in the dying phase, is possible but is frequently met with ethical and methodological challenges. This paper describes the challenges faced in a previous delirium screening study. Methods Within 72 hours of admission to an acute inpatient specialist palliative care unit one hundred consecutive patients over 18 years of age with advanced cancer were invited to be screened for delirium using validated screening tools. Results Of the 100 consecutive admissions 49 patients were unable to participate including seven who did not meet the inclusion criteria and nine (six families and three patients) who withheld consent. The remaining 33 patients were more unwell and closer to death than those who were recruited. Reasons for non- participation included being too unwell (ten), unresponsive (nine), died (two) or discharged (three) before recruitment and exceeding the 72hour time limit (nine). Conclusion Gate keeping and physical condition of patients were the main obstacles to recruitment and is consistent with barriers faced in previous studies involving palliative care and dying patients. While it is possible and necessary to conduct studies in palliative care, including the terminal phase, as reflective practitioners we must maintain the balance between the demands for evidence-based practice and our compassion and respect for our most vulnerable of patients.

Structural and material characterisation of insulated rail joints

Insulated rail joints are designed in a similar way to butt jointed steel structural systems, the difference being a purpose made gap between the main rail members to maintain electrical insulation for the proper functioning of the track circuitry at all times of train operation. When loaded wheels pass the gap, they induce an impact loading with the corresponding strains in the railhead edges exceeding the plastic limit significantly, which lead to metal flow across the gap thereby increasing the risk of short circuiting and impeding the proper functioning of the signalling and broken rail identification circuitries, of which the joints are a critical part. The performance of insulated rail joints under the passage of the wheel loading is complex due to the presence of a number of interacting components and hence is not well understood. This paper presents a dynamic wheel-rail contact-impact modelling method for the determination of the impact loading; a brief description of a field experiment to capture strain signatures for validating the predicted impact loading is also presented. The process and the results of the characterisation of the materials from virgin, in-service and damaged insulated rail joints using neutron diffraction method are also discussed.