Teachers' views on the nature of models

A semi-structured interview was used in Brazil to enquire into the 'notion of model' held by a total sample of 39 science teachers who were: employed in 'fundamental' (6-14 years) and 'medium' (15-17 years) schools; student science teachers currently doing their practicum; and university science teachers. Seven 'aspects' of their notions of a model were identified: the nature of a model, the use to which it can be put, the entities of which it consists, its relative uniqueness, the time span over which it is used, its status in the making of predictions, and the basis for the accreditation of its existence and use. Categories of meaning were identified for each of these aspects. The profiles of teachers' notions of 'model' in terms of the aspects and categories were complex, providing no support for the notion of 'Levels' in understanding. Teachers with degrees in chemistry or physics had different views about the notion of 'model' to those with degrees in biology or with teacher training certificates.

Effect of heat on rheology, surface hydrophobicity and molecular weight distribution of glutens extracted from flours with different bread-making quality

Gluten was extracted from flours of several different wheat varieties of varying baking quality. Creep compliance was measured at room temperature and tan 6 was measured over a range of temperatures from 25 to 95 degrees C. The extracted glutens were heat-treated for 20 min at 25, 40, 50, 60, 70 and 90 degrees C in a water bath, freeze-dried and ground to a fine powder. Tests were carried out for extractability in sodium dodecyl sulphate, free sulphydryl (SH) groups using Ellman's method, surface hydrophobicity and molecular weight (MW) distribution (MWD) using field-flow fractionation and multi-angle laser light scattering. With increasing temperature, the glutens showed a decrease in extractability, with the most rapid decreases occurring between 70 and 90 degrees C, a major transition in tan 6 at around 60 degrees C and a minor transition at 40 degrees C for most varieties, a decrease in free SH groups and surface hydrophobicity and a shift in the MWD towards higher MW. The poor bread-making variety Riband showed the highest values of tan delta and Newtonian compliance, the lowest content of free SH groups and the largest increase of HMW/LMW with increasing temperature. No significant correlations with baking volume were found between any of the measured parameters. (c) 2007 Elsevier Ltd. All rights reserved.

Effect of heat on rheology of gluten fractions from flours with different bread-making quality

Flours from wheat varieties of differing bread-making quality were fractionated using a sequential salt precipitation technique. The gluten fractions in the different varieties varied in the proportion of HMW, LMW glutenins and gliadins. Their rheological behaviour was examined using constant strain (2%) small deformation oscillation tests over frequencies ranging from 0.005 to 10 Hz, before and after heating at 90 degrees C. The fractions containing a higher proportion of HMW glutenins were associated with a predominantly elastic character, whereas fractions containing mostly gliadins exhibited a viscous-like behaviour. The frequency dependent rheological behaviour of fractions containing HMW proteins was less susceptible to heat, and their elastic character was maintained after heating, whereas the rheology of intermediate fractions and fractions containing mostly gliadins was more susceptible to heating, indicating a rapid change from viscous to elastic behaviour after heating. (c) 2006 Elsevier Ltd. All rights reserved.

Saccadic eye movements as an index of perceptual decision-making

One of the most common decisions we make is the one about where to move our eyes next. Here we examine the impact that processing the evidence supporting competing options has on saccade programming. Participants were asked to saccade to one of two possible visual targets indicated by a cloud of moving dots. We varied the evidence which supported saccade target choice by manipulating the proportion of dots moving towards one target or the other. The task was found to become easier as the evidence supporting target choice increased. This was reflected in an increase in percent correct and a decrease in saccade latency. The trajectory and landing position of saccades were found to deviate away from the non-selected target reflecting the choice of the target and the inhibition of the non-target. The extent of the deviation was found to increase with amount of sensory evidence supporting target choice. This shows that decision-making processes involved in saccade target choice have an impact on the spatial control of a saccade. This would seem to extend the notion of the processes involved in the control of saccade metrics beyond a competition between visual stimuli to one also reflecting a competition between options.

Communicating information about medication: the benefits of making it personal

Two experiments, using a controlled empirical methodology, investigated the effects of presenting information about medicines using a more personalised style of expression. In both studies, members of the general public were given a hypothetical scenario about visiting the doctor, being diagnosed with a particular illness, and being prescribed a medication. They were also given a written explanation about the medicine and were asked to provide ratings on a number of measures, including satisfaction, perceived risk to health, and intention to comply. In Experiment 1 the explanation focused only on possible side effects of the medicine, whereas in Experiment 2 a fuller explanation was provided, which included information about the illness, prescribed drug, its dosage and contraindications as well as its side effects. In both studies, use of a more personalised style resulted in significantly higher ratings of satisfaction and significantly lower ratings of likelihood of side effects occurring and of perceived risk to health. In Experiment 2 it also led to significantly improved recall for the written information.

Discussion on the importance of making things right

Critical notice of 'From metaphysics to ethics' by Frank Jackson.