A lattice spring model of heterogeneous materials with plasticity

A three-dimensional lattice spring model of a heterogeneous material is presented. For small deformations, the model is shown to recover the governing equations for an isotropic elastic medium. The model gives reasonable agreement with theoretical predictions for the elastic fields generated by a spherical inclusion, although for small particle sizes the discretization of the underlying lattice causes some departures from the predicted values. Plasticity is introduced by decreasing the elastic moduli locally whilst maintaining stress continuity. Results are presented for a spherical inclusion in a plastic matrix and are found to be in good agreement with the predictions of Wilner (1988 J. Mech. Phys. Solids 36 141-65).</p

Project Retrosight. Understanding the returns from cardiovascular and stroke research: Case Studies

Copyright @ 2011 RAND Europe. All rights reserved. The full text article is available via the link below.This project explores the impacts arising from cardiovascular and stroke research funded 15-20 years ago and attempts to draw out aspects of the research, researcher or environment that are associated with high or low impact. The project is a case study-based review of 29 cardiovascular and stroke research grants, funded in Australia, Canada and UK between 1989 and 1993. The case studies focused on the individual grants but considered the development of the investigators and ideas involved in the research projects from initiation to the present day. Grants were selected through a stratified random selection approach that aimed to include both high- and low-impact grants. The key messages are as follows: 1) The cases reveal that a large and diverse range of impacts arose from the 29 grants studied. 2) There are variations between the impacts derived from basic biomedical and clinical research. 3) There is no correlation between knowledge production and wider impacts 4) The majority of economic impacts identified come from a minority of projects. 5) We identified factors that appear to be associated with high and low impact. This report presents the key observations of the study and an overview of the methods involved. It has been written for funders of biomedical and health research and health services, health researchers, and policy makers in those fields. It will also be of interest to those involved in research and impact evaluation.This study was initiated with internal funding from RAND Europe and HERG, with continuing funding from the UK National Institute for Health Research, the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Canada and the National Heart Foundation of Australia. The UK Stroke Association and the British Heart Foundation provided support in kind through access to their archives

Project Retrosight. Understanding the returns from cardiovascular and stroke research: Methodology Report

Copyright @ 2011 RAND Europe. All rights reserved. The full text article is available via the link below.This project explores the impacts arising from cardiovascular and stroke research funded 15-20 years ago and attempts to draw out aspects of the research, researcher or environment that are associated with high or low impact. The project is a case study-based review of 29 cardiovascular and stroke research grants, funded in Australia, Canada and UK between 1989 and 1993. The case studies focused on the individual grants but considered the development of the investigators and ideas involved in the research projects from initiation to the present day. Grants were selected through a stratified random selection approach that aimed to include both high- and low-impact grants. The key messages are as follows: 1) The cases reveal that a large and diverse range of impacts arose from the 29 grants studied. 2) There are variations between the impacts derived from basic biomedical and clinical research. 3) There is no correlation between knowledge production and wider impacts 4) The majority of economic impacts identified come from a minority of projects. 5) We identified factors that appear to be associated with high and low impact. This report presents the key observations of the study and an overview of the methods involved. It has been written for funders of biomedical and health research and health services, health researchers, and policy makers in those fields. It will also be of interest to those involved in research and impact evaluation.This study was initiated with internal funding from RAND Europe and HERG, with continuing funding from the UK National Institute for Health Research, the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Canada and the National Heart Foundation of Australia. The UK Stroke Association and the British Heart Foundation provided support in kind through access to their archives

Reforming the cancer drug fund focus on drugs that might be shown to be cost effective

The Cancer Drug Fund was originally conceived as a temporary measure, until value based pricing for drugs was introduced, to give NHS cancer patients access to drugs not approved by NICE. Spending on these drugs rose from less than the £50m (€63m; $79m) budgeted for the first year in 2010-11 to well over £200m in 2013-14, and the budget for the scheme—now extended for a further two years—will reach £280m by 2016.1 The recent changes to the fund recognise the impossibility, within any sensible budget limit, of providing all the new cancer drugs that offer possible benefit to patients. More radical changes are needed to the working of the fund, given the failure to introduce value based pricing, so that it deals with the underlying problem of inadequate information on the effectiveness and cost effectiveness of new cancer drugs when used in the NHS

Understanding the fidelity effect when evaluating games with children

There have been a number of studies that have compared evaluation results from prototypes of different fidelities but very few of these are with children. This paper reports a comparative study of three prototypes ranging from low fidelity to high fidelity within the context of mobile games, using a between subject design with 37 participants aged 7 to 9. The children played a matching game on either an iPad, a paper prototype using screen shots of the actual game or a sketched version. Observational data was captured to establish the usability problems, and two tools from the Fun Toolkit were used to measure user experience. The results showed that there was little difference for user experience between the three prototypes and very few usability problems were unique to a specific prototype. The contribution of this paper is that children using low-fidelity prototypes can effectively evaluate games of this genre and style

Project Retrosight. Understanding the returns from cardiovascular and stroke research: Policy Report

Copyright @ 2011 RAND Europe. All rights reserved. The full text article and the summary of the article are both available via the links below.This project explores the impacts arising from cardiovascular and stroke research funded 15-20 years ago and attempts to draw out aspects of the research, researcher or environment that are associated with high or low impact. The project is a case study-based review of 29 cardiovascular and stroke research grants, funded in Australia, Canada and UK between 1989 and 1993. The case studies focused on the individual grants but considered the development of the investigators and ideas involved in the research projects from initiation to the present day. Grants were selected through a stratified random selection approach that aimed to include both high- and low-impact grants. The key messages are as follows: 1) The cases reveal that a large and diverse range of impacts arose from the 29 grants studied. 2) There are variations between the impacts derived from basic biomedical and clinical research. 3) There is no correlation between knowledge production and wider impacts 4) The majority of economic impacts identified come from a minority of projects. 5) We identified factors that appear to be associated with high and low impact. This report presents the key observations of the study and an overview of the methods involved. It has been written for funders of biomedical and health research and health services, health researchers, and policy makers in those fields. It will also be of interest to those involved in research and impact evaluation.This study was initiated with internal funding from RAND Europe and HERG, with continuing funding from the UK National Institute for Health Research, the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Canada and the National Heart Foundation of Australia. The UK Stroke Association and the British Heart Foundation provided support in kind through access to their archives

The "universal" radio/X-ray flux correlation : the case study of the black hole GX 339-4

The existing radio and X-ray flux correlation for Galactic black holes in the hard and quiescent states relies on a sample which is mostly dominated by two sources (GX 339-4 and V404 Cyg) observed in a single outburst. In this paper, we report on a series of radio and X-ray observations of the recurrent black hole GX 339-4 with the Australia Telescope Compact Array, the Rossi X-ray Timing Explorer and the Swift satellites. With our new long term campaign, we now have a total of 88 quasi-simultaneous radio and X-ray observations of GX 339-4 during its hard state, covering a total of seven outbursts over a 15--year period. Our new measurements represent the largest sample for a stellar mass black hole, without any bias from distance uncertainties, over the largest flux variations and down to a level that could be close to quiescence, making GX 339-4 the reference source for comparison with other accreting sources (black holes, neutrons stars, white dwarfs and active galactic nuclei). Our results demonstrate a very strong and stable coupling between radio and X-ray emission, despite several outbursts of different nature and separated by a period of quiescence. The radio and X-ray luminosity correlation of the form L_X ~L_Rad^0.62 +/-0.01 confirms the non-linear coupling between the jet and the inner accretion flow powers and better defines the standard correlation track in the radio-X-ray diagram for stellar mass black holes. We further note epochs of deviations from the fit that significantly exceed the measurement uncertainties, especially during the formation and destruction of the compact jets ...[abridged]. We incorporated our new data in a more global study of black hole candidates strongly supporting a scale invariance in the jet-accretion coupling of accreting black holes, and confirms the existence of two populations of sources in the radio/X-ray diagram.Comment: Paper accepted in MNRAS. 18 pages, 9 figure

Reliability of environmental DNA surveys to detect pond occupancy by newts at a national scale

The distribution assessment and monitoring of species is key to reliable environmental impact assessments and conservation interventions. Considerable effort is directed towards survey and monitoring of great crested newts (Triturus cristatus) in England. Surveys are increasingly undertaken using indirect methodologies, such as environmental DNA (eDNA). We used a large data set to estimate national pond occupancy rate, as well as false negative and false positive error rates, for commercial eDNA protocols. Additionally, we explored a range of habitat, landscape and climatic variables as predictors of pond occupancy. In England, 20% of ponds were estimated to be occupied by great crested newts. Pond sample collection error rates were estimated as 5.2% false negative and 1.5% false positive. Laboratory error indicated a negligible false negative rate when 12 qPCR replicates were used. Laboratory false positive error was estimated at 2% per qPCR replicate and is therefore exaggerated by high levels of laboratory replication. Including simple habitat suitability variables into the model revealed the importance of fish, plants and shading as predictors of newt presence. However, variables traditionally considered as important for newt presence may need more precise and consistent measurement if they are to be employed as reliable predictors in modelling exercises

An RShiny app for modelling environmental DNA data: accounting for false positive and false negative observation error

Environmental DNA (eDNA) surveys have become a popular tool for assessing the distribution of species. However, it is known that false positive and false negative observation error can occur at both stages of eDNA surveys, namely the field sampling stage and laboratory analysis stage. We present an RShiny app that implements the Griffin et al. (2020) statistical method, which accounts for false positive and false negative errors in both stages of eDNA surveys that target single species using quantitative PCR methods. Following Griffin et al. (2020), we employ a Bayesian approach and perform efficient Bayesian variable selection to identify important predictors for the probability of species presence as well as the probabilities of observation error at either stage. We demonstrate the RShiny app using a data set on great crested newts collected by Natural England in 2018, and we identify water quality, pond area, fish presence, macrophyte cover and frequency of drying as important predictors for species presence at a site. The state-of-the-art statistical method that we have implemented is the only one that has specifically been developed for the purposes of modelling false negative and false positive observation error in eDNA data. Our RShiny app is user-friendly, requires no prior knowledge of R and fits the models very efficiently. Therefore, it should be part of the tool-kit of any researcher or practitioner who is collecting or analysing eDNA data

Lessons from the evaluation of the UK's NHS R&D Implementation Methods Programme

Background: Concern about the effective use of research was a major factor behind the creation of the NHS R&D Programme in 1991. In 1994, an advisory group was established to identify research priorities in research implementation. The Implementation Methods Programme (IMP) flowed from this, and its commissioning group funded 36 projects. In 2000 responsibility for the programme passed to the National Co-ordinating Centre for NHS Service Delivery and Organisation R&D, which asked the Health Economics Research Group (HERG), Brunel University, to conduct an evaluation in 2002. By then most projects had been completed. This evaluation was intended to cover: the quality of outputs, lessons to be learnt about the communication strategy and the commissioning process, and the benefits from the projects. Methods: We adopted a wide range of quantitative and qualitative methods. They included: documentary analysis, interviews with key actors, questionnaires to the funded lead researchers, questionnaires to potential users, and desk analysis. Results: Quantitative assessment of outputs and dissemination revealed that the IMP funded useful research projects, some of which had considerable impact against the various categories in the HERG payback model, such as publications, further research, research training, impact on health policy, and clinical practice. Qualitative findings from interviews with advisory and commissioning group members indicated that when the IMP was established, implementation research was a relatively unexplored field. This was reflected in the understanding brought to their roles by members of the advisory and commissioning groups, in the way priorities for research were chosen and developed, and in how the research projects were commissioned. The ideological and methodological debates associated with these decisions have continued among those working in this field. The need for an effective communication strategy for the programme as a whole was particularly important. However, such a strategy was never developed, making it difficult to establish the general influence of the IMP as a programme. Conclusion: Our findings about the impact of the work funded, and the difficulties faced by those developing the IMP, have implications for the development of strategic programmes of research in general, as well as for the development of more effective research in this field