Pattern formation in the basilar papilla: evidence for cell rearrangement.

The avian basilar papilla is composed of hair and supporting cells arranged in a regular pattern in which the hair cells are surrounded and isolated from each other by supporting cell processes. This arrangement of cells, in which the apical borders of hair cells do not contact one another, may be generated by contact-mediated lateral inhibition. Little is known, however, about the way in which hair and supporting cells are organized during development. Whole mounts double-labeled with antibodies to the 275 kDa hair-cell antigen and the tight junction protein cingulin were therefore used to examine the development of cell patterns in the basilar papilla. Hair cells that contact each other at their apical borders are seen during early development, especially on embryonic days (E) 8 and 9, but are no longer observed after E12. Hair and supporting cell patterns were analyzed in three different areas of the papilla at E9 and E12. In two of these regions between E9 and E12, the ratio of supporting cells to hair cells does not change significantly, whereas there is an increase in both the number of supporting cells around each hair cell and the number of hair cells that each supporting cell contacts. In the third region examined, there is a dramatic rise in the number of supporting cells around each hair cell, which although accompanied by a small, significant increase in the ratio of supporting cells to hair cells cannot be accounted for by an increase in supporting cell numbers. These data show that a rearrangement of hair and supporting cells with respect to one another may be a fundamental process underlying the development of a regular pattern in the basilar papilla

Creating shareable representations of practice

This paper reports work on the use of asynchronous multimedia conferencing (AMC) to support collaborative continuing professional development. In particular it explores how we may use multimedia communications technologies to enable key elements of real‐world working knowledge, that are tacit and embedded in working practices, to be rendered into shareable forms for professional learning. We believe multimedia communications technology can offer innovative ways of capturing rich examples of working practices and tacit knowledge, and for sharing and subjecting these artefacts to scrutiny, debate and refinement within a community of learners. More explicitly, we see participants in a geographically distributed community of practice being able to create, annotate, discuss and reflect upon videoclips of their working practices within the multimedia conferencing environment. This paper summarizes some studies that cast light on how representations of practice may be captured for use in an AMC environment

Tests on a CAST 7 two-dimensional airfoil in a streamlining test section

A unique opportunity has arisen to test one and the same airfoil model of CAST-7 section in two wind tunnels having adaptive walled test sections. The tunnels are very similar in terms of size and the available range of test conditions, but differ principally in their wall setting algorithms. Detailed data from the tests of the model in the Southampton tunnel, are included with comparisons between various sources of data indicating that both adaptive walled test sections provide low interference test conditions

The generation of rolling moments with the superconducting solenoid model

The superconducting solenoid model is a pilot model core for levitation in a wind tunnel magnetic suspension system. This type of core would replace the ferromagnetic core typically installed in the model fuselage. For suspension purposes, the solenoid is operated upon by a set of electromagnets surrounding the wind tunnel which are to support and restrain the model at required positions and orientations under the influence of powerful aerodynamic disturbances. The subject of providing sources of magnets rolling moment for use when spanwise magnets, which can be used for winged models, are not available is covered. Several methods have emerged for generating a rolling moment based on the use of additional superconducting loops or magnetic poles positioned around or within the solenoid. Predictions of the moment capacities of superconducting loops in models sized for a large wind tunnel are presented. An existing prototype superconducting model proved a suitable vehicle for demonstrating and calibrating, at a smaller scale, some of the other roll elements based on magnetic pole devices. Calibration data are included

Consequences of ocean scale hypoxia constrained habitat for tropical pelagic fishes

Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. Recent studies show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas in the eastern tropical Pacific by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and mean dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the eastern tropical Pacific, but not in the western North Atlantic. where DO is not limiting. However. hypoxia-based habitat compression has not actually been demonstrated in the eastern tropical Atlantic Ocean, despite this region having similar oceanographic features to the eastern tropical Pacific. This paper explores the possibility that habitat compression of tropical pelagic fishes exists in the eastro tropical Atlantic and examines possible consequences of this phenomenon. We used Atlantic-wide catches of yellowfin tuna (Thunnus albacares) as an example why habitat compression off west Africa could eventually affect the total Atlantic stock

The university student experience of face-to-face and online discussions: coherence, reflection and meaning

This paper reports on an investigation into learning through discussions by undergraduate social work students. Second‐year students studying psychology for social work experienced discussions began with face‐to‐face tutorials, and then continued for some time after online. This study used closed‐ended questionnaires to investigate what students thought they were learning through discussions (their concepts), and how they engaged in the discussions face‐to‐face and online (their approaches). Significant associations were found among students’ concepts of discussions, approaches and levels of achievement. The results suggest that students who do not understand how discussions can help them to interrogate, reflect on and revise their ideas tended not to approach either face‐to‐face or online discussions in ways likely to improve their understanding or their levels of achievement. This type of insight is critical for teacher/designers wishing to create university experiences in which discussion is used to promote learning

Teaching in Context: Integrating Mathematical Thinking and Personal Development Planning into the Curriculum for Part-Time, Distance-Learning Engineering Students

This paper describes changes to the way mathematics is taught to engineering students at The Open University, moving away from service teaching via generic mathematics modules to incorporating mathematics teaching into the core engineering curriculum. Mathematics is taught in the context of engineering with the aim of reducing the emphasis on derivations and mathematical proofs and putting greater emphasis on understanding basic concepts and being able to create useful models. Mathematical methods are taught and practised, then extended and applied to different engineering contexts as students’ progress through modules, in order to develop students’ mathematical thinking and build confidence. Professional development planning has also been embedded into engineering teaching for improved context and relevance and a more integrated approach to assessment has been taken across the whole qualification

A Novel Antigen Sensitive to Calcium Chelation That is Associated with the Tip Links and Kinocilial Links of Sensory Hair Bundles

Tip links are extracellular, cell-surface-associated filaments of unknown molecular composition that are thought to gate the mechanotransducer channel of the sensory hair cell. They disappear from the hair bundle in response to calcium chelation and lanthanum treatment and resist degradation by the protease subtilisin. A monoclonal antibody derived from a hybridoma screen identified a novel antigen associated with tip links, the tip-link antigen. The tip-link antigen is also associated with kinocilial links, subtilisin-resistant filaments that are sensitive to calcium chelation and connect the kinocilium to the tallest stereocilia of the hair bundle. Furthermore, the tip-link antigen is expressed in the retina, where it is associated with the ciliary calyx, a ring of microvilli that surrounds the outer segment of the photoreceptor. The tip-link antigen rapidly disappears from the surface of the hair bundle in response to calcium chelation. It is also subtilisin resistant, relative to the ankle-link antigen, an antigen associated with another type of hair bundle link. The tip-link antigen is lanthanum sensitive and, like tip links, reappears on the surface of the hair bundle after calcium chelation. The monoclonal antibody to the tip-link antigen immunoprecipitates two concanavalin A-reactive polypeptides with apparent molecular masses of 200 and 250 kDa from detergent extracts of the retina. These results provide the first identification of a cell surface antigen associated with tip links, indicate that tip links share properties in common with kinocilial links, and reveal a second epitope that, along with the ankle-link antigen, is common to both sensory hair bundles and the ciliary calyx of photoreceptors

Networked learning in higher education: Practitioners’ perspectives

There is a growing use of a variety of communications media to provide networked learning in higher education. The practitioners in the field vary from experienced educators who have many years’ experience to early adopters who have begun to use networked technology for teaching and learning recently. Using interviews informed by a phenomenographic approach, this paper investigates the varieties of experience of practitioners of networked learning. It reports initial findings that represent an early stage of analysis. The findings point towards a common philosophy held by current practitioners of networked learning but a lack of ‘rules of thumb’. Practitioners expressed ideas close to a new paradigm in education but were cautious about specific design outcomes meeting expectations. This finding raises questions about design and whether networked learning is yet stable enough a field to provide guidance on best practice. The paper also reflects on criticisms of the phenomenographic method, in particular its reliance on interview data, and offers some possible ways of dealing with the criticisms

Using pattern languages to mediate theory–praxis conversations in design for networked learning

Educational design for networked learning is becoming more complex but also more inclusive, with teachers and learners playing more active roles in the design of tasks and of the learning environment. This paper connects emerging research on the use of design patterns and pattern languages with a conception of educational design as a conversation between theory and praxis. We illustrate the argument by drawing on recent empirical research and literature reviews from the field of networked learning