An investigation into the methods for modelling pre-existing cracks in phase field problems

Phase field (PF) models are an increasingly popular method of numerically modelling fracture problems. While research has focused on the practical applications and computational efficiency of PF methods, little discussion exists around the merits of different methods of prescribing initial cracks in PF fracture problems. This paper presents a comparison of three methods for modelling pre-existing cracks, through Dirichlet-type PF boundary conditions, an initial strain history term, and through physical discontinuities in the mesh. The comparison is made using the load-displacement responses for a common tensile benchmark fracture problem

Towards equity in land protection

Land protection not only supports vital ecosystem services but also poses important challenges for social equity. Three key concerns emerge from economic frameworks about land protection policies: potential lost local economic development, reinforcement of existing structural inequalities, and disparities in access to the benefits of protected land. This article reviews evidence for each concern and identifies research needs as well as potential improvements in policy that could better support equity goals. Pathways forward towards greater equity include specific mechanisms that can ensure local communities benefit from land protection, attention to issues of spatial impacts and timing, explicit prioritization of equity in land protection initiatives, and community-centred processes. Economists have and can continue to play a role in strengthening these dimensions of land protection policies

Disruption, Achievement and the Heterogeneous Benefits of Smaller Classes

With few exceptions, empirical research investigating the possibility of heterogeneous benefits of class size reduction lacks a conceptual framework about specific dimensions of potential heterogeneity. In this paper we develop a model of education production that incorporates disruption and student achievement and illustrates how these underlying sources of variation may drive heterogeneity in the benefits of class size reductions. We test for results consistent with this model using the Tennessee STAR data. The estimates show that students in higher poverty schools and with greater learning aptitude realize larger benefits from smaller classes.

Collection of anthropometry from older and physically impaired persons: traditional methods versus TC2 3-D body scanner

With advances in technology it is now possible to collect a wide range of anthropometric data, to a high degree of accuracy, using 3D light-based body scanners. This gives the potential to speed up the collection of anthropometric data for design purposes, to decrease processing time and data input required, and to reduce error due to inaccuracy of measurements taken using more traditional methods and equipment (anthropometer, stadiometer and sitting height table). However, when the data collection concerns older and/or physically impaired people there are serious issues for consideration when deciding on the best method to collect anthropometry. This paper discusses the issues arising when collecting data using both traditional methods of data collection and a first use by the experimental team of the TC2 3D body scanner, when faced with a ‘non-standard’ sample, during an EPSRC funded research project into issues surrounding transport usage by older and physically impaired people. Relevance to industry: Designing products, environments and services so that the increasing ageing population, as well as the physically impaired, can use them increases the potential market. To do this, up-to-date and relevant anthropometry is often needed. 3D light-based bodyscanners offer a potential fast way of obtaining this data, and this paper discusses some of the issues with using one scanner with older and disabled people

National strategy for the prevention and management of transfusion-associated hepatitis

The screening of potential blood donors for the hepatitis B (HBV) and C (HCV) viruses has decreased the risk of transfusion-associated hepatitis, There remains. however, a lack of consensus on a number of issues including methods for screening of blood donors and the management of donors found to have markers of hepatitis virus infection. This document outlines the recommendations of a large group of interested individuals including blood transfusion service managers, primary care health authorities, epidemiologists, Virologists, pathologists, gastroenterologists and hepatologists drawn from both the public and the private sector

In vitro studies on the control of human myometrial gap junctions

In this study human myometrial tissues were examined for the presence of gap junctions by quantitative electron microscopy before and after incubation in tissue culture media with and without indomethacin. The area of gap junctions was very low in tissues from pregnant women at term but not labor, before incubation. After 24 and 48 h incubation without any treatment, segments of some of the same tissues developed many gap junctions and other tissues contained few junctions. Prostaglandin E (PGE), prostaglandin F (PGF) and prostaglandin F metabolite (PGF metabolite) levels in the media at various times were measured by radioimmunoassay. The prostaglandins increased progressively during the incubation period. Treatment of tissues with indomethacin decreased prostaglandin levels in the media and increased the numbers of gap junctions in those control tissues that developed few junctions over the same incubation interval. We conclude that the capacity of human myometrial tissues to develop gap junctions in vitro may depend upon a maturational stage in preparation for labor. Furthermore, our results suggest that products of the cyclo-oxygenase or lipoxygenase pathways may control the presence of gap junctions in the human myometrium and that changes in synthesis in these patterns may occur as part of the maturational process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26692/1/0000239.pd