Mechanism for tensile strain hardening in high performance cement-based fiber reinforced composites

The mechanism responsible for the improvement in tensile strain capacity of FRC (fiber reinforced concrete) as a result of the addition of high volume fraction of discontinuous fibers was investigated, using energy changes associated with cracking. The energy terms considered include: matrix fracture energy, matrix strain energy. debonding energy, fiber strain energy and fiber frictional energy.Assuming that the first observed crack is also the failure crack, it was found that multiple cracking occurs in high performance FRC. In such composites the energy needed to open the critical cracks exceeds the energy needed to form a new crack. The analysis predicts that the major energy term determining this behavior is the fiber debonding energy.Multiple cracking was observed in fiber reinforced small densified DSP (particles) containing a high volume fraction (higher than 3%) of fine and short steel fibers. Because crack localization did not occur during multiple cracking, very large increases in total strain capacity were achieved with increasing fiber volume fraction. At 12% fiber volume fraction, a total strain capacity of about 0[middle dot]2% was measured from flexures tests; an increase of about 15 to 20 times over that of the plain matrix.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29589/1/0000678.pd

The drugs don't sell: DIY heart health and the over-the-counter statin experience

This paper draws on a study of over-the-counter statins to provide a critical account of the figure of the ‘pharmaceutical consumer’ as a key actor in the pharmaceuticalisation literature. A low dose statin, promising to reduce cardiovascular risk, was reclassified to allow sale in pharmacies in the UK in 2004. We analysed professional and policy debates about the new product, promotional and sales information, and interviews with consumers and potential consumers conducted between 2008 and 2011, to consider the different consumer identities invoked by these diverse actors. While policymakers constructed an image of ‘the citizen-consumer’ who would take responsibility for heart health through exercising the choice to purchase a drug that was effectively rationed on the NHS and medical professionals raised concerns about ‘a flawed consumer’ who was likely to misuse the product, both these groups assumed that there would be a market for the drug. By contrast, those who bought the product or potentially fell within its target market might appear as ‘health consumers’, seeking out and paying for different food and lifestyle products and services, including those targeting high cholesterol. However, they were reluctant ‘pharmaceutical consumers’ who either preferred to take medication on the advice of a doctor, or sought to minimize medicine use. In comparison to previous studies, our analysis builds understanding of individual consumers in a market, rather than collective action for access to drugs (or, less commonly, compensation for adverse effects). Where some theories of pharmaceuticalisation have presented consumers as creating pressure for expanding markets, our data suggests that sociologists should be cautious about assuming there will be demand for new pharmaceutical products, especially those aimed at prevention or asymptomatic conditions, even in burgeoning health markets

Prevention is better than cure, but...: Preventive medication as a risk to ordinariness?

Preventive health remains at the forefront of public health concerns; recent initiatives, such as the NHS health check, may lead to recommendations for medication in response to the identification of 'at risk' individuals. Little is known about lay views of preventive medication. This paper uses the case of aspirin as a prophylactic against heart disease to explore views among people invited to screening for a trial investigating the efficacy of such an approach. Qualitative interviews (N=46) and focus groups (N=5, participants 31) revealed dilemmas about preventive medication in the form of clashes between norms: first, in general terms, assumptions about the benefit of prevention were complicated by dislike of medication; second, the individual duty to engage in prevention was complicated by the need not to be over involved with one's own health; third, the potential appeal of this alternative approach to health promotion was complicated by unease about the implications of encouraging irresponsible behaviour among others. Though respondents made different decisions about using the drug, they reported very similar ways of trying to resolve these conflicts, drawing upon concepts of necessity and legitimisation and the special ordinariness of the particular dru

Semi-Analytic Stellar Structure in Scalar-Tensor Gravity

Precision tests of gravity can be used to constrain the properties of hypothetical very light scalar fields, but these tests depend crucially on how macroscopic astrophysical objects couple to the new scalar field. We develop quasi-analytic methods for solving the equations of stellar structure using scalar-tensor gravity, with the goal of seeing how stellar properties depend on assumptions made about the scalar coupling at a microscopic level. We illustrate these methods by applying them to Brans-Dicke scalars, and their generalization in which the scalar-matter coupling is a weak function of the scalar field. The four observable parameters that characterize the fields external to a spherically symmetric star (the stellar radius, R, mass, M, scalar `charge', Q, and the scalar's asymptotic value, phi_infty) are subject to two relations because of the matching to the interior solution, generalizing the usual mass-radius, M(R), relation of General Relativity. We identify how these relations depend on the microscopic scalar couplings, agreeing with earlier workers when comparisons are possible. Explicit analytical solutions are obtained for the instructive toy model of constant-density stars, whose properties we compare to more realistic equations of state for neutron star models.Comment: 39 pages, 9 figure

CMB Anomalies from Imperfect Dark Energy: Confrontation with the Data

We test anisotropic dark energy models with the 7-year WMAP temperature observations data. In the presence of imperfect sources, due to large-scale gradients or anisotropies in the dark energy field, the CMB sky will be distorted anisotropically on its way to us by the ISW effect. The signal covariance matrix then becomes nondiagonal for small multipoles, but at $\ell \gtrsim 20$ the anisotropy is negligible. We parametrize possible violations of rotational invariance in the late universe by the magnitude of a post-Friedmannian deviation from isotropy and its scale dependence. This allows to obtain hints on possible imperfect nature of dark energy and the large-angle anomalous features in the CMB. A robust statistical analysis, subjected to various tests and consistency checks, is performed to compare the predicted correlations with those obtained from the satellite-measured CMB full sky maps. The preferred axis point towards $(l,b) = (168^\circ, -31^\circ)$ and the amplitude of the anisotropy is $\varpi_0 = (0.51\pm 0.94)$ (1$\sigma$ deviation quoted). The best-fit model has a steep blue anisotropic spectrum ($n_{\mathrm{de}} = 3.1\pm1.5$).Comment: 11 pages, 4 figure

Born Digital: Guidance for Donors, Dealers, and Archival Repositories

The report provides recommendations to help ensure the physical and intellectual well-being of materials created and managed in digital form ("born digital") that are transferred from donors to archival repositories. The report is presented in four sections, each of which provides an overview of a key area of concern: initial collection review, privacy and intellectual property, key stages in acquiring digital materials, and post-acquisition review by the repository. Each section concludes with two lists of recommendations: one for donors and dealers, and a second for repository staff. Appendixes provide more specific information about possible staffing activities, as well as a list of resources and ready-to-use checklists that incorporate recommendations from throughout the report. Ten archivists and curators from institutions in the United States and United Kingdom collaborated on the report