Fracture and fatigue strength of grouted macadams

Grouted macadams form a class of material which provides significant advantages in comparison to both concrete and conventional asphalt, having both rut resistance and a degree of flexibility. This paper presents a series of laboratory tests on several grouted macadam mixtures, for stiffness, fatigue and low temperature fracture. The variables explored include binder grade and content, aggregate size and gradation, and grout strength. Although the material is found to perform fundamentally as an asphalt, there are several significant differences in the form of fatigue behavior found compared to that usually expected from an asphalt. In particular the effect of varying binder content is found to be markedly different. The results are discussed in terms of optimizing mixture design in order to obtain the most desirable combination of properties (stiffness, fatigue strength, low temperature fracture resistance). Discussion is also presented regarding the possible role of grouted macadams as base or binder courses within highway pavements, and the conclusion is drawn that they are likely to provide an economical solution in many circumstances owing to their superior mechanical properties

TRADE LIBERALISATION UNDER THE DOHA DEVELOPMENT AGENDA; OPTIONS AND CONSEQUENCES FOR AFRICA

This study provides a quantitative estimate of the potential economic consequences of multilateral trade reform under the WTO for Africa using a framework that explicitly incorporates issues of concern to the region, such as preference erosion, loss of tariff revenue, and trade facilitation. It also examines the impact of OECD agricultural support programmes on economic welfare and specialisation in Africa. In the static version of the GTAP model, the study finds that full liberalisation of trade would increase global welfare (income) by 0.3 per cent, but would add 0.7 per cent annually to income in the African region. Sub-Saharan Africa and, to a lesser extent, Southern Africa, are vulnerable to partial trade reforms as they incur losses from partial reform while all other regions derive positive gains from a liberalisation of minor scope.International Relations/Trade,

Análisis del módulo de rigidez y la resistencia a fatiga de mezclas asfálticas recicladas en frio fabricadas con betún espumado para su uso en el diseño de firmes para aeropuertos

Cold recycled bound materials (CRBMs) provide an economic and environmental advantage for pavements since they decrease energy and raw material consumption. However, design methods for airfield pavements do not include key CRBM properties. In this paper an empirical-mechanistic method is used to study airfield pavement design with CRBM in order to develop design guidance. The aim of the paper is to obtain the inputs related to material properties needed for use in this method. For this purpose, CRBM containing reclaimed asphalt, with fly ash, cement and foamed bitumen as stabilising agents, was characterised. The methodology included indirect tensile stiffness modulus (ITSM) and indirect tensile fatigue tests (ITFT) in strain control mode. The inputs needed for a pavement design analysis with CRBM were then obtained. The results showed the importance of further study on CRBM fatigue to understand the behaviour of these mixes under cyclic loading.El uso de mezclas asfálticas recicladas en frío (MARF) proporciona ventajas tanto económicas como medioambientales al disminuir el consumo de energía y materias primas. Sin embargo, los métodos de diseño para firmes de aeropuertos no incluyen las propiedades de MARFs. En este artículo un método empírico-mecanístico se emplea para estudiar el diseño de firmes de aeropuertos con MARF. El objetivo es obtener los inputs relacionados con las propiedades de MARF necesarios para llevar a cabo el diseño del pavimento. Con este propósito, MARF con asfalto reciclado, ceniza volante, cemento y betún espumado ha sido caracterizado. La metodología incluye ensayo de tracción indirecta para la obtención del módulo de rigidez y ensayo de fatiga con tracción indirecta en modo de deformación controlada. Los inputs necesarios han sido obtenidos y los resultados muestran la importancia de un estudio adicional del comportamiento a fatiga de MARF para entender su comportamiento bajo cargas cíclicas

The effect of using rest periods in 4PB tests on the fatigue life of grouted macadams

Four-point bending tests are commonly used to assess the fatigue resistance of bi-tuminous bound materials that are used in road pavements. However, it is difficult to establish a reliable relationship between the laboratory test results and the field performance of the mate-rial. In order to predict the real life of the pavement, shift factors are normally used to convert the fatigue results obtained in the laboratory onto the actual fatigue life of the material in the field. Those shift factors depend on the type of test used, the testing conditions and the type of mixture used. In this study, an attempt was made to establish a shift factor for grouted mac-adams, based on four-point bending fatigue test results carried out with rest periods between the loading cycles. The result obtained was used to define a fatigue criterion for pavement design with grouted macadams

A protocol for an economic evaluation of a polypill in patients with established or at high risk of cardiovascular disease in a UK NHS setting: RUPEE (NHS) study.

INTRODUCTION: The 'Use of a Multi-drug Pill in Reducing cardiovascular Events' (UMPIRE) trial was a randomised controlled clinical trial evaluating the impact of a polypill strategy on adherence to indicated medication in a population with established cardiovascular disease (CVD) of or at high risk thereof. The aim of Researching the UMPIRE Processes for Economic Evaluation in the National Health Service (RUPEE NHS) is to estimate the potential health economic impact of a polypill strategy for CVD prevention within the NHS using UMPIRE trial and other relevant data. This paper describes the design of a modelled economic evaluation of the impact of increased adherence to the polypill versus usual care among the UK UMPIRE participants. METHODS AND ANALYSIS: As recommended by the International Society for Pharmacoeconomics and Outcomes Research and the Society for Medical Decision Making modelling guidelines, a review of published CVD models was undertaken to identify the most appropriate modelling approach and structure. The review was carried out in the electronic databases, MEDLINE and EMBASE. 40 CVD models were identified from 57 studies, the majority of economic models were health state transition cohort models and individual-level simulation models. The findings were discussed with clinical experts to confirm the approach and structure. An individual simulation approach was identified as the most suitable method to capture the heterogeneity in the population at CVD risk. RUPEE-NHS will use UMPIRE trial data on adherence to estimate the long-term cost-effectiveness of the polypill strategy. DISSEMINATION: The evaluation findings will be presented in open-access scientific and healthcare policy journals and at national and international conferences. We will also present findings to NHS policy makers and pharmaceutical companies

Catastrophic regime shifts in model ecological communities are true phase transitions

Ecosystems often undergo abrupt regime shifts in response to gradual external changes. These shifts are theoretically understood as a regime switch between alternative stable states of the ecosystem dynamical response to smooth changes in external conditions. Usual models introduce nonlinearities in the macroscopic dynamics of the ecosystem that lead to different stable attractors among which the shift takes place. Here we propose an alternative explanation of catastrophic regime shifts based on a recent model that pictures ecological communities as systems in continuous fluctuation, according to certain transition probabilities, between different micro-states in the phase space of viable communities. We introduce a spontaneous extinction rate that accounts for gradual changes in external conditions, and upon variations on this control parameter the system undergoes a regime shift with similar features to those previously reported. Under our microscopic viewpoint we recover the main results obtained in previous theoretical and empirical work (anomalous variance, hysteresis cycles, trophic cascades). The model predicts a gradual loss of species in trophic levels from bottom to top near the transition. But more importantly, the spectral analysis of the transition probability matrix allows us to rigorously establish that we are observing the fingerprints, in a finite size system, of a true phase transition driven by background extinctions.Comment: 19 pages, 11 figures, revised versio

A Protocol for an economic evaluation of a polypill in patients with established or at high risk of cardiovascular disease in a UK NHS setting: RUPEE (NHS) study

Copyright © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. Introduction: The ‘Use of a Multi-drug Pill in Reducing cardiovascular Events’ (UMPIRE) trial was a randomised controlled clinical trial evaluating the impact of a polypill strategy on adherence to indicated medication in a population with established cardiovascular disease (CVD) of or at high risk thereof. The aim of Researching the UMPIRE Processes for Economic Evaluation in the National Health Service (RUPEE NHS) is to estimate the potential health economic impact of a polypill strategy for CVD prevention within the NHS using UMPIRE trial and other relevant data. This paper describes the design of a modelled economic evaluation of the impact of increased adherence to the polypill versus usual care among the UK UMPIRE participants. Methods and analysis: As recommended by the International Society for Pharmacoeconomics and Outcomes Research and the Society for Medical Decision Making modelling guidelines, a review of published CVD models was undertaken to identify the most appropriate modelling approach and structure. The review was carried out in the electronic databases, MEDLINE and EMBASE. 40 CVD models were identified from 57 studies, the majority of economic models were health state transition cohort models and individual-level simulation models. The findings were discussed with clinical experts to confirm the approach and structure. An individual simulation approach was identified as the most suitable method to capture the heterogeneity in the population at CVD risk. RUPEE-NHS will use UMPIRE trial data on adherence to estimate the long-term cost-effectiveness of the polypill strategy. Dissemination: The evaluation findings will be presented in open-access scientific and healthcare policy journals and at national and international conferences. We will also present findings to NHS policy makers and pharmaceutical companies

A Catalogue of Field Horizontal Branch Stars Aligned with High Velocity Clouds

We present a catalogue of 430 Field Horizontal Branch (FHB) stars, selected from the Hamburg/ESO Survey (HES), which fortuitously align with high column density neutral hydrogen (HI) High-Velocity Cloud (HVC) gas. These stars are ideal candidates for absorption-line studies of HVCs, attempts at which have been made for almost 40 years with little success. A parent sample of 8321 HES FHB stars was used to extract HI spectra along each line-of-sight, using the HI Parkes All-Sky Survey. All lines-of-sight aligned with high velocity HI emission with peak brightness temperatures greater than 120mK were examined. The HI spectra of these 430 probes were visually screened and cross-referenced with several HVC catalogues. In a forthcoming paper, we report on the results of high-resolution spectroscopic observations of a sample of stars drawn from this catalogue.Comment: 7 pages, 4 figures. ApJS accepted. Full catalogue and all online-only images available at http://astronomy.swin.edu.au/staff/cthom/catalogue/index.htm

The Clumping Transition in Niche Competition: a Robust Critical Phenomenon

We show analytically and numerically that the appearance of lumps and gaps in the distribution of n competing species along a niche axis is a robust phenomenon whenever the finiteness of the niche space is taken into account. In this case depending if the niche width of the species $\sigma$ is above or below a threshold $\sigma_c$, which for large n coincides with 2/n, there are two different regimes. For $\sigma > sigma_c$ the lumpy pattern emerges directly from the dominant eigenvector of the competition matrix because its corresponding eigenvalue becomes negative. For $\sigma </- sigma_c$ the lumpy pattern disappears. Furthermore, this clumping transition exhibits critical slowing down as $\sigma$ is approached from above. We also find that the number of lumps of species vs. $\sigma$ displays a stair-step structure. The positions of these steps are distributed according to a power-law. It is thus straightforward to predict the number of groups that can be packed along a niche axis and it coincides with field measurements for a wide range of the model parameters.Comment: 16 pages, 7 figures; http://iopscience.iop.org/1742-5468/2010/05/P0500