Axisymmetric buckling of a spherical shell embedded in an elastic medium under uniaxial stress at infinity

The problem of a thin spherical linearly-elastic shell, perfectly bonded to an infinite linearly-elastic medium is considered. A constant axisymmetric stress field is applied at infinity in the matrix, and the displacement and stress fields in the shell and matrix are evaluated by means of harmonic potential functions. In order to examine the stability of this solution, the buckling problem of a shell which experiences this deformation is considered. Using Koiter's nonlinear shallow shell theory, restricting buckling patterns to those which are axisymmetric, and using the Rayleigh–Ritz method by expanding the buckling patterns in an infinite series of Legendre functions, an eigenvalue problem for the coefficients in the infinite series is determined. This system is truncated and solved numerically in order to analyse the behaviour of the shell as it undergoes buckling, and to identify the critical buckling stress in two cases — namely where the shell is hollow and the stress at infinity is either uniaxial or radial

Dynamics and Sizes of the Fireball at Freeze-out

Analyzing the m_t-spectrum and two-particle correlations of negative hadrons from 158 AGeV/c Pb+Pb collisions at slightly forward rapidities we find a (thermal) freeze-out temperature of about 100 MeV and transverse flow with approximately 0.55c. The M_t-dependence of the correlation radii prefers a box-like transverse density profile over a Gaussian. From an analysis of the pion phase-space density we find pion chemical potential of approximately 60 MeV at thermal freeze-out.Comment: Contribution to the XVth Particle and Nuclei International Conference, PANIC'99, Uppsala June, 10-16, 1999; 4 pages, 2 figures, needs Elsevier style file espcrc1.sty (provided

Blood pressure responses in healthy older people to 50 g carbohydrate drinks with differing glycaemic effects

The aim of the present study was to determine the effects on blood pressure response of 50 g carbohydrate drinks with differing glycaemic effects in ten healthy elderly subjects (age >65 years; randomized crossover design). Systolic (SBP), diastolic (DBP) and mean arterial (MAP) blood pressure, heart rate and plasma glucose levels were determined following ingestion of equal volumes (379 ml) of water and 50 g carbohydrate drinks with differing reported glycaemic indices (GI) (surrogate marker for glycaemic effect): (1) low-GI: Apple & Cherry Juice; (2) intermediate-GI: Fanta Orange; (3) high-glucose. Glucose (SBP and DBP P,0·001; MAP P¼0·005) and Fanta Orange (SBP P¼0·005; DBP and MAP P,0·001) ingestion caused a significant decrease in BP whilst blood pressure increased (SBP P¼0·008; MAP P¼0·005) from baseline following Apple & Cherry Juice ingestion. Water had no significant effect on postprandial blood pressure. Fanta Orange and Apple & Cherry Juice caused similar (P¼0·679) glycaemic effects, which were significantly greater than water, but lower than glucose (P,0·001). There was no significant correlation between the glycaemic effect of the carbohydrate drinks and there was no change in blood pressure from baseline (SBP r 20·123, P¼0·509; DBP r 20·051, P¼0·784; MAP r 20·069, P¼0·712). Apple & Cherry Juice and Fanta Orange had similar glycaemic effects, but differing effects on blood pressure. Therefore, it is unlikely that the glycaemic effect of a drink can be used to predict the subsequent cardiovascular response.Renuka Visvanathan, Richard Chen, Michael Horowitz and Ian Chapma

Telling stories: engaging critical literacy through urban legends in an English secondary school

Non-dominant voices have been further marginalised in the most recent National Curriculum in England (DfE 2014) and those working across the English teaching profession often find the subject framed according to narrow, assessment driven models and prescribed skill sets. This article brings together two perspectives on the importance of literacy education that remains rooted in young people's everyday experiences of place. Katie is a newly qualified secondary English teacher. She will share examples taken from her own classroom practice of the ways in which she has responded to stories told by young people about the places in which they live. Susan is a tutor of Initial Teacher Education (ITE). She suggests that Katie’s approach provides persuasive exemplification of how engagement with alternatives to a dominant view of literacy should remain a key objective for those working with beginning teachers of English. For Katie's students, urban legends are powerful texts which offer the means to explore what we do when we tell stories, both inside and outside the English classroom. As will be shown, such stories are telling examples of the resources young people can bring to critical literacy learning in current classrooms. In the context of the dominance of a narrow, mandated experience of English as a subject, the imperative becomes even greater to recognise stories such as those shared by Katie's students as opportunities for authentic, creative and critical engagement with text

Early lexical characteristics of toddlers with cleft lip and palate

pre-printMain Outcome Measures: The groups were compared for size of expressive lexicon reported on the MacArthur Communicative Development Inventory and the percentage of words beginning with obstruents and sonorants produced in a language sample. Differences between groups in the percentage of word initial consonants correct on the language sample were also examined. Results: Although expressive vocabulary was comparable at 13 months of age for both groups, size of the lexicon for the cleft group was significantly smaller than that for the noncleft group at 21 and 27 months of age. Toddlers with cleft palate produced significantly more words beginning with sonorants and fewer words beginning with obstruents in their spontaneous speech samples. They were also less accurate when producing word initial obstruents compared with the noncleft group. Conclusions: Toddlers with cleft palate demonstrate a slower rate of lexical development compared with their noncleft peers. The preference that toddlers with cleft palate demonstrate for words beginning with sonorants could suggest they are selecting words that begin with consonants that are easier for them to produce. An alternative explanation might be that because these children are less accurate in the production of obstruent consonants, listeners may not always identify obstruents when they occur

Reconstructing the Source in Heavy Ion Collisions from Particle Interferometry

The preliminary CERN SPS NA49 Pb+Pb 158 GeV/A negative one- and two-particle spectra at mid-rapidity are consistent with a source of temperature 130 MeV, lifetime 9 fm/c, transverse flow 0.35, and a transverse geometric size which is twice as large as the cold Pb nucleus.Comment: Proceedings for Quark Matter 97; 4 pages, 2 eps-figure

Open resources for case studies and assignments

Resources not designed for educational use can be successfully used educationally. For example, publications by bodies such as the United Nations or government departments can be rich resources for case studies and assignments in an educational context. Such resources are often freely available on the web, and so can be considered open educational resources. The use of this type of resource for case studies and assignments is considered in the context of two related level-3 modules (final year undergraduate) produced by the UK Open University. Both modules are concerned with digital technology, and both situate the technology in a wider social context. Both courses are also concerned with developing students’ skills of independent investigation. The prime benefits of this type of resource are shown to be their authenticity and authority. In using these resources, students are dealing with materials that are often produced and used by professional practitioners. However, there are potential pitfalls: students often need a great deal of help to make good use of these resources, and the resources are liable to change or disappear from the web unpredictably. The paper concludes that using this type of open educational resource should not be seen as a time-saver or an easy option for course designers. Instead, as with other open educational resources, using these resources can present course designers with problems of location, selection and incorporation. That is, where can suitable resources be found, which parts can be used successfully, and how can these resources be incorporated into resources created by the course designers themselves

Modeling growth in biological materials

The biomechanical modeling of growing tissues has recently become an area of intense interest. In particular, the interplay between growth patterns and mechanical stress is of great importance, with possible applications to arterial mechanics, embryo morphogenesis, tumor development, and bone remodeling. This review aims to give an overview of the theories that have been used to model these phenomena, categorized according to whether the tissue is considered as a continuum object or a collection of cells. Among the continuum models discussed is the deformation gradient decomposition method, which allows a residual stress field to develop from an incompatible growth field. The cell-based models are further subdivided into cellular automata, center-dynamics, and vertex-dynamics models. Of these the second two are considered in more detail, especially with regard to their treatment of cell-cell interactions and cell division. The review concludes by assessing the prospects for reconciliation between these two fundamentally different approaches to tissue growth, and by identifying possible avenues for further research. © 2012 Society for Industrial and Applied Mathematics