Sandstone response to salt weathering following simulated fire damage: a comparison of furnace heating and fire.

Fire has long been recognized as an agent of rock weathering. Our understanding of the impact of fire on stone comes either from early anecdotal evidence, or from more recent laboratory simulation studies, using furnaces to simulate the effects of fire. This paper suggests that knowledge derived from simulated heating experiments is based on the preconceptions of the experiment designer – when using a furnace to simulate fire, the operator decides on the maximum temperature and the duration of the experiment. These are key factors in determining the response of the stone to fire, and if these are removed from realworld observations then knowledge based on these simulations must be questioned. To explore the differences between heating sandstone in a furnace and a real fire, sample blocks of Peakmoor Sandstone were subjected to different stress histories in combination (lime rendering and removal, furnace heating or fire, frost and salt weathering). Block response to furnace heating and fire is discussed, with emphasis placed on the non-uniformity of the fire and of block response to fire in contrast to the uniform response to surface heating in a furnace. Subsequent response to salt weathering (by a 10% solution of sodium chloride and magnesium sulphate) was then monitored by weight loss. Blocks that had experienced fire showed a more unpredictable response to salt weathering than those that had undergone furnace heating – spalling of corners and rapid catastrophic weight loss were evidenced in blocks that had been subjected to fire, after periods of relative quiescence. An important physical side-effect of the fire was soot accumulation, which created a waxy, relatively impermeable layer on some blocks. This layer repelled water and hindered salt ingress, but eventually detached when salt, able to enter the substrate through more permeable areas, concentrated and crystallized behind it, resulting in rapid weight loss and accelerated decay. Copyright ©2007 John Wiley & Sons, Ltd.

Medical Students' views of a career in Geriatric Medicine; Multi-Centre Qualitative Analysis

Medical students frequently have negative preconceptions of a career in Geriatric Medicine. In ta qualitative analysis of the free text from 789 response from Medical students in Scotland and Northern Ireland, we show that clinical attachment seffectively challenge negative student views and more positive statements about future careers in Geriatric Medicine emerged at the end of the attachment.

How standardised patients award global scores in OSCEs: a qualitative study

Standardized patients (SPs) are often asked to award global scores on the humanistic aspects of a candidate’s performance in an OSCE. However, little is known about the process by which SPs arrive at their mark.
Five focus groups of SPs, using a convenience sample, were used to collect data until saturation. Thematic analysis was carried out independently by three researchers using a grounded theory approach.

Four major themes contributed to their decision-making process: environment, relationships within the exam, preparedness for the task and expectations of the student’s performance. Environmental factors included the station itself, the rating scale and examiner fatigue. Relationship factors included first impressions, the sense of purpose derived from examining and a tendency to mirror the examiner’s reaction. Factors relating to preparedness for task involved experience as an SP and technical aspects, such as the need for calibration. Lastly, expectations of performance were related to preconceptions about what makes a ‘good’ student, including their level of studies, appearance and technical performance.

In assessing students, SPs drew on their wider attitudes and experiences. SPs did not limit their assessment to humanistic traits but often included technical performance. Thus, SPs to some extent assessed a similar construct to examiners and this may help to explain the increased reliability associated with using SP scores. SP global scores are a useful adjunct but the process by which SPs award marks is complex and provides a challenge for training and standardisation.