Solutions to certain classes of linearized reaction–diffusion equations

A systematic study is presented for the linear manifold of solutions to a generic system of reaction–diffusion equations in the neighborhood of a constant uniform (equilibrium) solution. The theory pertains directly to an arbitrary number of reacting and diffusing molecular or biological species in an arbitrary bounded spatial (1-, 2- or 3-dimensional) region with an impermeable boundary, so that the normal gradient of any species concentration function is zero at all boundary points. The stability analysis developed by previous authors is streamlined here for the case of two reacting and diffusing species, worked out completely for the case of three species, and made more amenable to specialized treatment for cases with four or more species. With the use of modern algebraic computational methods, explicit analytical general solutions to the linearized reaction–diffusion equations are derived for certain classes of model theories. These results either apply directly or admit extension to a wide range of practical reaction–diffusion problems in physical chemistry and biology.     

Hippocampal terminology: concepts,misconceptions, origins

The mammalian hippocampus is certainly one of the best investigated brain regions. It fascinates neuroscientists particularly because of its important role in memory. The names for the various parts of the hippocampal formation were created in the course of the first thorough explorations of human brain anatomy. The present, internationally agreed terminology reflects an unfortunate muddle that has been going on for several hundred years. Not surprisingly, even today the origins of some of the names are not always given correctly. It is generally accepted that the Italian anatomist Arantius was the first to apply the term 'hippocampus' to part of that region in the human brain. To later authors, however, this name appeared more or less enigmatic and they proposed various other terms. Yet careful reading of the entire original text of Arantius leads to the conclusion that it was not the hippocampus in our modern terms but the dentate gyrus which he compared to a little sea horse or a silkworm.     

Dynamics of the frame in visual composition

The position of an object within a visual composition produces an effect on the observer. Does an observer see the object as strong and active if it is in the center of the picture, in one corner, “floating” off-center? Does the framing of the object or the field surrounding it give an object more meaning? Forty-four college students rated six framed, black-andwhite, single-object pictures. The 264 observations were subjected to principal axis factoring, resulting in four dimensions: activity, potency, evaluative, and verticality.     

The flow of instructors through the segmented labor markets of academe

This paper focuses on two categories of teaching personnel, those inside and outside of the tenure stream, who together provide instruction in North American post-secondary institutions. Segmented labor market thinking is used to examine the extent to which entry to the tenure stream is achieved by those who begin on appointments outside of these internal labor markets. Tabulations provided by Statistics Canada on the fate of seven entering cohorts of full-time instructors at Canadian universites (excluding Quebec) seven years after their initial appointment are analyzed. We find that a consistent and meaningful proportion of each cohort achieves entrance to the tenure stream from an initial external labor market appointment and that such an employment history accounts for almost half of all entrants who actually remain. Thus, despite the hardships of many who have no opportunity to be considered for continuing employment, external labor market appointees are, nonetheless, an important pool for recruitment of permanent faculty. This study adds to the growing body of knowledge that identifies their major role in the provision of post-secondary instruction. Disadvantages accruing to women and young academics and their relationships to external labor markets are discussed, as are the implications of these patterns for the changing career trajectories of those currently entering academe.     

Syndicate methods: two styles compared

A comparison is made between two styles of syndicate work. In the first, referred to as unstructured (U), groups range in size from four to six students. In the second, referred to as formal (F), groups are eight to ten in size and tend to adopt a formal chairman-secretary structure. This latter type is here illustrated by one of the authors from his experience in a Medical School, where the tasks presented to the students are complex problem boxes requiring many man-hours from different departments for their creation. The analysis of the U type is based on the second author's experience in an American university and an English polytechnic.The areas examined are, first, the size and the composition of the groups; second the tutor's role; third, the development of higher order cognitive skills in the students; and fourth the management of research in this field. Questions are raised particularly in relation to the consolidation of syndicate work, to ensure command of the basic material; to the change of role required of both teachers and students; to the influence of the institutional culture on the work; to the adaptation of assessment techniques to measure development in the higher order skills; and to the possibility that investigation needs to be carried out on actual courses by teachers, students and researchers in collaboration.     

Research and the Challenges of Contemporary School Leadership: The Contribution of Critical Scholarship

There is a widespread policy assumption that school leaders such as headteachers and governors need to have 'raining courses' which are constituted by a growing corpus of Education Management Studies (EMS) if they are to achieve successfully current schooling goals of 'effectiveness', 'quality', 'excellence' and 'value for money' Another body of work which attempts to address these issues in a wider cultural framework and which may be called Critical Leadership Studies (CLS) is regarded as interesting for those studying for higher graduate qualifications but hardly relevant for everyday school busyness. While EMS is constructed as 'practical'and therefore a necessary constituent of the National Professional Qualification for Headteachers and other training courses for school leaders, CLS is constructed as 'academic' and more suitable for the EdD seminar. It will be argued here that both cultural analysis and recent research shows this to be a simplistic and reductionist view with dangerous policy consequences. Critical scholarship in education has much to offer to those meeting the everyday challenges of school leadership. In particular, feminist critical scholarship offers oppositional models to both traditional and market forms of patriarchal school leadership.     

Writing performance assessments: how important is extended time?

Students in Grades 5 and 8 completed a 30-minute writing performance assessment and a writing performance assessment completed over 3 days. Assessments were evaluated on four traits (ideas, organization, conventions, and sentence fluency). A significant interaction was found at Grade 5 between length of time allotted for the assessment and students' educational classification (general or special education). Grade 5 students performed significantly better on the 3-day writing assessment, with students in special education benefiting the most. At Grade 8, there were no differences between scores on the 30-minute and the 3-day assessments. No significant differences were found in students' writing performance across various types of discourse (narrative, imaginative, persuasive, and expository); significant differences were reported across certain writing traits. We shared three hypotheses for reported differences: (a) students' proficiency with the writing process, (b) scoring scale bias, and (c) differences in the revision behaviors of developing and mature writers. Educational implications related to statewide test programs are discussed.     

Preference for signaled shock phenomenon: Direct and indirect evidence for modifiability factors in the shuttlebox

The experiments reported here investigated whether unauthorized shock modification is a factor which mediates the preference for signaled shock phenomenon (PSS) in the shuttlebox. This factor appearednot to have a critical role in PSS on the basis of earlier experiments which reported that PSS occurred in the shuttle-box even when shock was made unmodifiable by scrambling. However, the scrambling used in these experiments was not complete. In Experiments I and II reported here, no PSS occurred with completely scrambled grids; the phenomenon emerged only with unscrambled shock. Experiment III reports evidence indicating a connection between directly assessed modification and PSS with unscrambled shock, with PSS emerging only when modification had begun to occur. The pattern of results from these shuttlebox experiments parallels that found in an earlier study of PSS using a symmetrical-choice, barpress preparation.