Maternal imagination: Reconceiving first impressions

The concept of maternal imagination, whereby the disordered thoughts and impressions of pregnant women are used to explain the prevalence of monstrous births, was at its height during the early modern period, albeit it with many prior and subsequent manifestations. Against a more familiar, and enduring, medieval and Renaissance context of supernatural agency at work, the device of MI was seen as a 'naturalistic' model more in keeping with the advent of Enlightenment scientism. Nonetheless, the debate around it was ferocious and indicative more of a masculine anxiety about female desire and generative power than of a concern for impartial explanation. In problematizing a simply descriptive approach to archival material, my purpose is to explore what is at stake in the competing discourses that seem alternately, and even simultaneously, to empower and degrade the place of the mother. What is the unspoken of an historical debate that prefigures our contemporary interest in feminine excess?

FROM LINE-DRAWINGS TO IMPRESSIONS OF 3D OBJECTS - DEVELOPING A MODEL TO ACCOUNT FOR THE SHAPES THAT PEOPLE SEE

The interpretations people attach to line drawings reflect shape-related processes in human vision. Their divergences from expectations embodied in related machine vision traditions are summarized, and used to suggest how human vision decomposes the task of interpretation. A model called IO implements this idea. It first identifies geometrically regular, local fragments. Initial decisions fix edge orientations, and this information constrains decisions about other properties. Relations between fragments are explored, beginning with weak consistency checks and moving to fuller ones. IO's output captures multiple distinctive characteristics of human performance, and it suggests steady progress towards understanding shape-related visual processes is possible.

Degradation of poly-L-lactide. Part 1: in vitro and in vivo physiological temperature degradation

Poly-L-Lactide is a bioresorbable polymer which degrades through hydrolysis of its ester linkage influenced by initial molecular weight and degree of crystallinity. Polymers belonging to the aliphatic polyester family currently represent the most attractive group of polymers that meet the medical and physical demands for safe clinical applications. Compression moulded PLLA pellets were produced as rods, sterilized and degraded both in vitro and in vivo (sub-dermal implantation model). The material molecular weight, crystallinity, mechanical strength and thermal properties were evaluated. In both in vitro and in vivo environments, degradation proceeded at the same rate and followed the general sequence of aliphatic polyester degradation, ruling out enzymes accelerating the degradation rate in vivo. By 44 weeks duration of implantation the PLLA rods were still biocompatible, before any mass loss was observed.

Degradation of poly-L-lactide. Part2 : increased temperature accelerated degradation

Poly-L-lactide (PLLA) is one of the most significant members of a group of polymers regarded as bioresorbable. The degradation of PLLA proceeds through hydrolysis of the ester linkages in the polymer's backbone; however, the time for the complete resorption of orthopaedic devices manufactured from PLLA is known to be in excess of five years in a normal physiological environment. To evaluate the degradation of PLLA in an accelerated time period, PLLA pellets were processed by compression moulding into tensile test specimens, prior to being sterilized by ethylene oxide gas (EtO) and degraded in a phosphate-buffered solution (PBS) at both 50°C and 70°C. On retrieval, at predetermined time intervals, procedures were used to evaluate the material's molecular weight, crystallinity, mechanical strength, and thermal properties. The results from this study suggest that at both 50°C and 70°C, degradation proceeds by a very similar mechanism to that observed at 37°C in vitro and in vivo. The degradation models developed also confirmed the dependence of mass loss, melting temperature, and glass transition temperature (Tg) on the polymer's molecular weight throughout degradation. Although increased temperature appears to be a suitable method for accelerating the degradation of PLLA, relative to its physiological degradation rate, concerns still remain over the validity of testing above the polymer's Tg and the significance of autocatalysis at increased temperatures.

A case study in group learning and supervision

Student units or the group-based field education and supervision of social work students offer many advantages as an efficient field placement model as well as opportunities for students to learn from each other through sharing knowledge, working collaboratively, hearing different perspectives and discussing issues. Despite the enormous potential of student units, they are a largely uncharted territory. There is a scarcity of literature on the topic and very few guidelines as to the provision of student units. The term student unit covers a broad range of student group learning opportunities and activities. This study explores this model of social work field education and its implications for student field work learning in a group context. The discussion is based on a review of the experiences, opinions and impressions of participants of an actual university based social work student unit.

Tracing emotion: an overview

Computational research with continuous representations depends on obtaining continuous representations from human labellers. The main method used for that purpose is tracing. Tracing raises a range of challenging issues, both psychological and statistical. Naive assumptions about these issues are easy to make, and can lead to inappropriate requirements and uses. The natural function of traces is to capture perceived affect, and as such they belong in long traditions of research on both perception and emotion. Experiments on several types of material provide information about their characteristics, particularly the ratings on which people tend to agree. Disagreement is not necessarily a problem in the technique. It may correctly show that people’s impressions of emotion diverge more than commonly thought. A new system, Gtrace, is designed to let rating studies capitalise on a decade of experience and address the research questions that are opened up by the data now available.

Measurement and modelling of perceived slant in surfaces represented by freely viewed line drawings

Simple pictures under everyday viewing conditions evoke impressions of surfaces oriented in depth. These impressions have been studied by measuring the slants of perceived surfaces, with probes (rotating arrowheads) designed to respect the distinctive character of depicted scenes. Converging arguments indicated that the perceived orientation of the probes was near theoretical values. A series of experiments showed that subjects formed well-defined impressions of depicted surface orientation. The literature suggests that perceived objects might be flattened', but that was not the general rule. Instead, both mean slant and uncertainty fitted models in which slant estimates are derived in a relatively straightforward way from local relations in the picture. Simplifying pictures tended to make orientation estimates less certain, particularly away from the natural anchor points (vertical and horizontal). The shape of the object affected all aspects of the observed-object/percept relationship. Individual differences were large, and suggest that different individuals used different relationships as a basis for their estimates. Overall, data suggest that everyday picture perception is strongly selective and weakly integrative. In particular, depicted slant is estimated by finding a picture feature which will be strongly related to it if the object contains a particular regularity, not by additive integration of evidence from multiple directly and indirectly relevant sources.