Facilitating online discussion, tutoring and moderating skills in clinical psychology lecturers

The inclusion of online approaches in clinical psychology training has necessitated an examination of the skills required by trainers. This paper describes the development of a short tutorial to promote online discussion tutoring and moderation skills in clinical psychology lecturers

Older hip fracture patients: three groups with different needs

BACKGROUND: Norway, and particularly Oslo, has the highest reported incidence of hip fractures in the world. It is increasingly common to care for older hip fracture patients in orthogeriatric units where orthopaedic care is combined with interdisciplinary geriatric care. The characteristics and needs of older hip fracture patients are poorly described. The aim of this paper is to describe the characteristics of these patients in order to better understand their need for care and rehabilitation. METHODS: This is an observational study based on a quality register for all patients 65+ years in an orthogeriatric unit who are operated for a hip fracture. The unit covers 250,000 inhabitants in Oslo. Patient data were collected in the aim of quality control. The quality database includes demographic, medical, and functional data collected from routine assessment by the interdisciplinary team. RESULTS: From January 2007 to September 2009, 1010 patients, included 241 (24%) from long-term care institutions, were enrolled in the database. Mean age was 85.1 years (SD 7.1), 76% were female, and 83% had experienced an indoor fall. Chronic diseases were registered in 88%, and 38% of the community-dwelling patients had pre-fracture cognitive impairment defined as IQCODE-SF > 3.6. Complications were observed in 51% of the patients, of which the most common were a need for blood transfusion, delirium, and urinary tract infections. Post-operative orthopaedic infections were rare (3.1%). Patients from long-term care were older, (87 vs. 84 years, p < 0.001), more had American Society of Anaesthesiologists (ASA) score >/= 3 (67% vs. 48%, p < 0.001) and a higher number of chronic medical conditions (mean 2.2 vs. 1.6, p < 0.001). Among community-dwelling patients, those who had fallen indoors were older, more often female, had ASA score >/= 3, chronic medical conditions, impairment in pre-fracture ADL and cognitive function, and more complications during hospital stay. CONCLUSIONS: Older hip fracture patients in this orthogeriatric unit may be divided into three groups; patients who are relatively fit and have experienced outdoors falls (17%), frail community-dwelling patients who have fallen indoors (59%), and patients from long-term care institutions (24%). Different caring pathways are needed for these groups

Time-Dependent Mechanical Behavior of Proton Exchange Membrane Fuel Cell Electrodes

The electrodes used for Proton Exchange Membrane Fuel Cells (PEMFCs) are typically painted or sprayed onto the membrane during manufacturing, making it difficult to directly characterize their mechanical behavior as a stand-alone material. An experimental-numerical hybrid technique is devised to extract the electrode properties from the experimentally measured properties of Nafion® 211 membrane1 and a membrane electrode assembly (MEA) based on Nafion® 211 membrane at various temperatures, humidities, and strain rates. Within the linear regime, the rule-of-mixtures assuming an iso-strain condition is used to calculate the rate-dependent Young\u27s modulus of the electrodes. Beyond the linear regime, reverse analysis is conducted using finite element models of the MEA to determine the non-linear behavior of the electrodes. The mechanical damage mechanisms that occur in the MEA during tensile loading are also investigated through interrupted tension tests and then incorporated into the finite element models for determining the electrode behavior. The results suggest that the electrodes have similar behavior to Nafion® 211 membrane as functions of strain rate, temperature and humidity, but with lower Young\u27s modulus and proportional limit

Time-Dependent Mechanical Behavior of Proton Exchange Membrane Fuel Cell Electrodes

The electrodes used for Proton Exchange Membrane Fuel Cells (PEMFCs) are typically painted or sprayed onto the membrane during manufacturing, making it difficult to directly characterize their mechanical behavior as a stand-alone material. An experimental-numerical hybrid technique is devised to extract the electrode properties from the experimentally measured properties of Nafion® 211 membrane1 and a membrane electrode assembly (MEA) based on Nafion® 211 membrane at various temperatures, humidities, and strain rates. Within the linear regime, the rule-of-mixtures assuming an iso-strain condition is used to calculate the rate-dependent Young\u27s modulus of the electrodes. Beyond the linear regime, reverse analysis is conducted using finite element models of the MEA to determine the non-linear behavior of the electrodes. The mechanical damage mechanisms that occur in the MEA during tensile loading are also investigated through interrupted tension tests and then incorporated into the finite element models for determining the electrode behavior. The results suggest that the electrodes have similar behavior to Nafion® 211 membrane as functions of strain rate, temperature and humidity, but with lower Young\u27s modulus and proportional limit

Effect of Time-Dependent Material Properties on the Mechanical Behavior of PFSA Membranes Subjected to Humidity Cycling

A viscoelastic-plastic constitutive model is developed to characterize the time-dependent mechanical response of perfluorosulphonic acid (PFSA) membranes. This model is then used in finite element simulations of a representative fuel cell unit, (consisting of electrodes, gas diffusion layer and bipolar plates) subjected to standardized relative humidity (RH) cycling test conditions. The effects of hold times at constant RH, the feed rate of humidified air and sorption rate of water into the membrane on the stress response are investigated. While the longer hold times at high and low humidity lead to considerable redistribution of the stresses, the lower feed and sorption rates were found to reduce the overall stress levels in the membrane. The redistribution and reduction in stress magnitudes along with inelastic deformation during hydration eventually lead to development of residual tensile stresses after dehydration. Simulations indicate that these tensile stresses can be on the order of 9–10 MPa which may lead to mechanical degradation of the membrane. The simulation results show that time-dependent properties can have a significant effect on the in-plane stress response of the membrane

Effect of Time-Dependent Material Properties on the Mechanical Behavior of PFSA Membranes Subjected to Humidity Cycling

A viscoelastic-plastic constitutive model is developed to characterize the time-dependent mechanical response of perfluorosulphonic acid (PFSA) membranes. This model is then used in finite element simulations of a representative fuel cell unit, (consisting of electrodes, gas diffusion layer and bipolar plates) subjected to standardized relative humidity (RH) cycling test conditions. The effects of hold times at constant RH, the feed rate of humidified air and sorption rate of water into the membrane on the stress response are investigated. While the longer hold times at high and low humidity lead to considerable redistribution of the stresses, the lower feed and sorption rates were found to reduce the overall stress levels in the membrane. The redistribution and reduction in stress magnitudes along with inelastic deformation during hydration eventually lead to development of residual tensile stresses after dehydration. Simulations indicate that these tensile stresses can be on the order of 9–10 MPa which may lead to mechanical degradation of the membrane. The simulation results show that time-dependent properties can have a significant effect on the in-plane stress response of the membrane

An Experimental Investigation of Strain Rate, Temperature and Humidity Effects on the Mechanical Behavior of a Perfluorosulfonic Acid Membrane

The time-dependent hygro-thermal mechanical behavior of a perfluorosulfonic acid (PFSA) membrane (Nafion® 211 membrane) commonly used in Proton Exchange Membrane Fuel Cells (PEMFCs) is investigated at selected strain rates for a broad range of temperatures and humidities. Tensile tests and relaxation tests are conducted to determine Young’s modulus and proportional limit stress as functions of strain rate, temperature and humidity. The results show that Young’s modulus and proportional limit stress increase as the strain rate increases, and decrease as the temperature or humidity increases. The results also show that the mechanical response of Nafion® 211 membrane is more sensitive to typical changes in strain rate or temperature than to typical changes in humidity. In addition, two temperature/humidity cycles are conducted to determine the steady state swelling behavior of Nafion® 211 membrane as a function of temperature and humidity. The results show that the membrane swells with increasing temperature and humidity, and that there is little or no hygro-thermal history effect for the swelling strains

An Experimental Investigation of Strain Rate, Temperature and Humidity Effects on the Mechanical Behavior of a Perfluorosulfonic Acid Membrane

The time-dependent hygro-thermal mechanical behavior of a perfluorosulfonic acid (PFSA) membrane (Nafion® 211 membrane) commonly used in Proton Exchange Membrane Fuel Cells (PEMFCs) is investigated at selected strain rates for a broad range of temperatures and humidities. Tensile tests and relaxation tests are conducted to determine Young’s modulus and proportional limit stress as functions of strain rate, temperature and humidity. The results show that Young’s modulus and proportional limit stress increase as the strain rate increases, and decrease as the temperature or humidity increases. The results also show that the mechanical response of Nafion® 211 membrane is more sensitive to typical changes in strain rate or temperature than to typical changes in humidity. In addition, two temperature/humidity cycles are conducted to determine the steady state swelling behavior of Nafion® 211 membrane as a function of temperature and humidity. The results show that the membrane swells with increasing temperature and humidity, and that there is little or no hygro-thermal history effect for the swelling strains

Time-Dependent Mechanical Response of a Composite PFSA Membrane

The mechanical response of a composite fuel cell membrane, made from layers of reinforced and unreinforced PFSA material, is investigated via both experimental and numerical means. First, the time-dependent mechanical properties for the reinforced layers are measured for a range of environmental and loading conditions. A three-network, viscoelastic-plastic constitutive model is developed to characterize the mechanical response of this reinforced membrane material. This constitutive model is then used in finite element simulations of a fuel cell unit (consisting of composite membrane, electrodes, gas diffusion layer and bipolar plates) where the effect of relative humidity (RH) cycling on the stress response of the composite membrane is investigated. Using numerical simulations, various layering configurations for the composite membrane and different load cases are studied. The investigation provides insight into the stress response of the membrane and suggests possible configurations that may improve the effective membrane life