Wave speeds and Green’s tensors for shear wave propagation in incompressible, hyperelastic materials with uniaxial stretch

Assessing elastic material properties from shear wave propagation following an acoustic radiation force impulse (ARFI) excitation is difficult in anisotropic materials because of the complex relations among the propagation direction, shear wave polarizations, and material symmetries. In this paper, we describe a method to calculate shear wave signals using Green's tensor methods in an incompressible, hyperelastic material with uniaxial stretch. Phase and group velocities are determined for SH and SV propagation modes as a function of stretch by constructing the equation of motion from the Cauchy stress tensor determined from the strain energy density. The Green's tensor is expressed as the sum of contributions from the SH and SV propagation modes with the SH contribution determined using a closed-form expression and the SV contribution determined by numerical integration. Results are presented for a Mooney-Rivlin material model with a tall Gaussian excitation similar to an ARFI excitation. For an experimental configuration with a tilted material symmetry axis, results show that shear wave signals exhibit complex structures such as shear splitting that are characteristic of both the SH and SV propagation modes

Within the web: the family/practitioner relationship in the context of chronic childhood illness

This study explores the phenomenon of the relationships between practitioners and families who have a child with a chronic illness. Using a heremeneutic phenomenological method informed by the writings of Martin Heidegger [1889-1976] and Hans-Georg Gadamer [1900-2002], this study provides an understanding of the meaning of 'being in relationship' from the perspective of both families and practitioners.Study participants include ten family groups who have a child with a chronic illness and twelve practitioners from the disciplines of nursing, medicine, dietetics, physiotherapy and speech therapy who work with children with chronic illness. Narrative audiotaped interviewing was the means by which the participants told their stories about times that relationships worked well and when they did not. These stories uncover the every day realities of 'being in relationship' and provide another understanding of the relationship between family and practitioner.The findings of this thesis suggest that chronic childhood illness 'throws' families and practitioners together into a web of relationships that must work for the sake of the child. The relationship is primarily conducted between adults. Children are usually excluded. In order to understand and manage the child's illness, practitioners and families 'go around' and act 'in-between' relationships. While the quality of the relationship from the family perspective is not essential to the chronic illness journey, relationships are more successful when practitioners recognise the uniqueness of each family web. The nature of the relationship is often simple, yet it co-exists with complexity. This thesis proposes that a 'companion relationship' between practitioners and family may offer a more effective and satisfying way of working. It also challenges practitioners to consider the voice of children within health care relationships

The connexin mimetic peptide Gap27 and Cx43-Knockdown reveal differential roles for Connexin43 in wound closure events in skin model systems

In the epidermis, remodelling of Connexin43 is a key event in wound closure. However, controversy between the role of connexin channel and non-channel functions exist. We compared the impact of SiRNA targeted to Connexin43 and the connexin mimetic peptide Gap27 on scrape wound closure rates and hemichannel signalling in adult keratinocytes (AK) and fibroblasts sourced from juvenile foreskin (JFF), human neonatal fibroblasts (HNDF) and adult dermal tissue (ADF). The impact of these agents, following 24 h exposure, on (encoding Connexin43), and gene expression, and Connexin43 and pSmad3 protein expression levels, were examined by qPCR and Western Blot respectively. In all cell types Gap27 (100-100 μM) attenuated hemichannel activity. In AK and JFF cells, Gap27 (100 nM-100 μM) enhanced scrape wound closure rates by ~50% but did not influence movement in HNDF or ADF cells. In both JF and AK cells, exposure to Gap27 for 24 h reduced the level of Cx43 protein expression but did not affect the level in ADF and HNDF cells. Connexin43-SiRNA enhanced scrape wound closure in all the cell types under investigation. In HDNF and ADF, Connexin43-SiRNA enhanced cell proliferation rates, with enhanced proliferation also observed following exposure of HDNF to Gap27. By contrast, in JFF and AK cells no changes in proliferation occurred. In JFF cells, Connexin43-SiRNA enhanced levels and in JFF and ADF cells both Connexin43-SiRNA and Gap27 enhanced pSmad3 protein expression levels. We conclude that Connexin43 signalling plays an important role in cell migration in keratinocytes and foreskin derived fibroblasts, however, different pathways are evoked and in dermal derived adult and neonatal fibroblasts, inhibition of Connexin43 signalling plays a more significant role in regulating cell proliferation than cell migration

Have we substantially underestimated the impact of improved sanitation coverage on child health?:A generalized additive model panel analysis of global data on child mortality and malnutrition

Background: Although widely accepted as being one of the most important public health advances of the past hundred years, the contribution that improving sanitation coverage can make to child health is still unclear, especially since the publication of two large studies of sanitation in India which found no effect on child morbidity. We hypothesis that the value of sanitation does not come directly from use of improved sanitation but from improving community coverage. If this is so we further hypothesise that the relationship between sanitation coverage and child health will be non-linear and that most of any health improvement will accrue as sanitation becomes universal. Methods: We report a fixed effects panel analysis of country level data using Generalized Additive Models in R. Outcome variables were under 5 childhood mortality, neonatal mortality, under 5 childhood mortality from diarrhoea, proportion of children under 5 with stunting and with underweight. Predictor variables were % coverage by improved sanitation, improved water source, Gross Domestic Product per capita and Health Expenditure per capita. We also identified three studies reporting incidence of diarrhoea in children under five alongside gains in community coverage in improved sanitation. Findings: For each of the five outcome variables, sanitation coverage was independently associated with the outcome but this association was highly non-linear. Improving sanitation coverage was very strongly associated with under 5 years diarrhoea mortality, under 5years all-cause mortality, and all-cause neonatal mortality. There was a decline as sanitation coverage increased up to about 20% but then no further decline was seen until about 70% (60% for diarrhoea mortality and 80% for neonatal mortality, respectively). The association was less strong for stunting and underweight but a threshold about 50% coverage was also seen. Three large trials of sanitation on diarrhoea morbidity gave results that were similar to what would have been predicted by our model. Conclusions: Improving sanitation coverage may be one of the more effective means to reduce childhood mortality, but only if high levels of community coverage are achieved. Studies of the impact of sanitation that focus on the individual’s use of improved sanitation as the predictor variable rather than community coverage is likely to severely underestimate the impact of sanitation

Memory texts and memory work: Performances of memory in and with visual media

The online version of this article can be found at: http://mss.sagepub.com/content/early/2010/05/24/175069801037003

The Stellar Halo and Outer Disk of M33

We present first results from a Keck DEIMOS spectroscopic survey of red giant branch (RGB) stars in M33. The radial velocity distributions of the stars in our fields are well described by three Gaussian components, corresponding to a candidate halo component with an uncorrected radial velocity dispersion of σ ≃ 50 km s^(-1), a candidate disk component with a dispersion σ ≃ 16 km s^(-1), and a third component offset from the disk by ~50 km s^(-1), but for which the dispersion is not well constrained. By comparing our data to a model of M33 based on its H I rotation curve, we find that the stellar disk is offset in velocity by ~25 km s^(-1) from the H I disk, consistent with the warping that exists between these components. The spectroscopic metallicity of the halo component is [Fe/H] ≃ -1.5, significantly more metal-poor than the implied metallicity of the disk population ([Fe/H] ≃ -0.9), which also has a broader color dispersion than the halo population. These data represent the first detections of individual stars in the halo of M33 and, despite being ~10 times less massive than M31 or the Milky Way, all three of these disk galaxies have stellar halo components with a similar metallicity. The color distribution of the third component is different from the disk and the halo but is similar to that expected for a single, coeval, stellar population, and could represent a stellar stream. More observations are required to determine the true nature of this intriguing third kinematic component in M33

GBM heterogeneity as a function of variable epidermal growth factor receptor variant III activity.

Abnormal activation of the epidermal growth factor receptor (EGFR) due to a deletion of exons 2-7 of EGFR (EGFRvIII) is a common alteration in glioblastoma (GBM). While this alteration can drive gliomagenesis, tumors harboring EGFRvIII are heterogeneous. To investigate the role for EGFRvIII activation in tumor phenotype we used a neural progenitor cell-based murine model of GBM driven by EGFR signaling and generated tumor progenitor cells with high and low EGFRvIII activation, pEGFRHi and pEGFRLo. In vivo, ex vivo, and in vitro studies suggested a direct association between EGFRvIII activity and increased tumor cell proliferation, decreased tumor cell adhesion to the extracellular matrix, and altered progenitor cell phenotype. Time-lapse confocal imaging of tumor cells in brain slice cultures demonstrated blood vessel co-option by tumor cells and highlighted differences in invasive pattern. Inhibition of EGFR signaling in pEGFRHi promoted cell differentiation and increased cell-matrix adhesion. Conversely, increased EGFRvIII activation in pEGFRLo reduced cell-matrix adhesion. Our study using a murine model for GBM driven by a single genetic driver, suggests differences in EGFR activation contribute to tumor heterogeneity and aggressiveness

Tun: Reliable Modalities

Unified ubiquitous models have led to many essential advances, including redundancy and sen- sor networks. In fact, few developers would disagree with the understanding of cache coherence. In order to fulfill this goal, we prove that though the acclaimed homogeneous algorithm for the refinement of superpages by G. Wang et al. [14] is maximally efficient, replication and multicast systems can agree to surmount this issue