Olard F.,Research and Development Division
Road Materials and Pavement Design | Year: 2012
Aggregate packing concepts developed in the field of high-performance cement concretes, initially by Caquot (1937) then by contemporary researchers since the 1970s, were transposed to the field of asphalt concretes. These concepts, associated with the use of the gyratory compactor on aggregates only, enabled the development of a new laboratory design procedure of dense high-modulus asphalt concretes. These mixes are characterized by single or double gap-graded curves, great coarse aggregate interlock and no need for low penetration grade bitumens to fulfil the European EME2 specification requirements, in particular the 14,000 MPa stiffness modulus value at 15°C. In addition, the use of polymer modified binders (PMBs), at a content of about 4% up to 4.5%, combined with such an optimized aggregate packing leads to the design of the so-called high-performance asphalt concretes (HPAs) characterized by great compactability, very high stiffness modulus and high fatigue resistance in a single formulation, allowing for reduced pavement thickness and increased longevity. Moreover, the proposed mix design and the 4-4.5% binder content makes PMBs use affordable in base courses. Laboratory assessment of such materials consisted in the evaluation of compactability, moisture resistance, rutting resistance at 60°C, complex stiffness modulus at 15°C and fatigue resistance at 10°C. Apart from these results, the paper also addresses the successful application of this new material on different job sites, located mainly in France. The proposed HPA material may be potentially considered as a relevant solution for sustainable long life pavements that do not deteriorate structurally, needing only timely surface maintenance. © 2012 Taylor & Francis.
Nakaya M.,Yokogawa Electric Corporation |
Li X.,Research and Development Division
Journal of Process Control | Year: 2013
A tracking simulator that runs in parallel with the plant and exactly simulates dynamic plant behavior has been developed. This tracking simulator is currently in the validation phase at a commercial petrochemical plant site. The future prediction function of the tracking simulator is expected to have a major impact on plant operations, improvement, and control design. The tracking simulator is strongly dependent on the physical model based on physical and chemical laws, and cannot simulate unknown phenomena in the plant. A hybrid model consisting of a physical model and a statistical model based on historical plant operation data was proposed. The estimation accuracy of the statistical model was improved using the virtual input from the tracking simulator. Although the Kalman filter technique is applied to conventional software sensors for quality estimation as a model updating function, deterioration of estimation accuracy is often seen with marked changes in plant behavior and the analyzers shut down. To resolve these issues, we applied Just-In-Time modeling based on the historical data modeling technique with the tracking simulator, and the plant model coverage of the tracking simulator was expanded for various processes. © 2012 Elsevier Ltd. All rights reserved.
Ansah E.K.,Research and Development Division |
Powell-Jackson T.,London School of Hygiene and Tropical Medicine
BMC Public Health | Year: 2013
Background: The research community relies heavily on measures of healthcare utilization from household surveys to understand health seeking choices and to evaluate interventions in developing countries. Such measures are known to suffer from recall problems but there is limited evidence of whether the method of data collection affects evaluation findings. We compared the results of a randomized trial of free healthcare using utilization data from two sources. Methods. Data are from a study in Ghana, in which 2,194 households containing 2,592 children under 5 y old were randomized into a prepayment scheme providing free primary and some referral care, or to a control group whose families paid user fees for healthcare. Data on morbidity and health seeking behaviour were collected using a standard household survey administered at endline and a pictorial diary given to households over a six month period, collected at monthly intervals. Results: Self-reported measures of morbidity and healthcare utilization were substantially lower in the household survey than the pictorial diary when the recall period was over a month. Introducing free healthcare had a positive effect on primary care visits based on the pictorial diary and a non-significant negative effect according to the household survey. Using any clinic visit in the past month as the outcome, the difference in the effect of free care between the two data collection methods was 3.6 percentage points (p = 0.078). Conclusions: The findings raise methodological concerns about measures of healthcare utilization from household surveys, particularly in the evaluation of health financing interventions. © 2013 Ansah and Powell-Jackson; licensee BioMed Central Ltd.
Traver B.E.,Virginia Polytechnic Institute and State University |
Williams M.R.,Research and Development Division |
Fell R.D.,Virginia Polytechnic Institute and State University
Journal of Invertebrate Pathology | Year: 2012
Nosema ceranae is a microsporidian parasite of the European honey bee, Apis mellifera, that is found worldwide and in multiple Apis spp.; however, little is known about the effects of N. ceranae on A. mellifera. Previous studies using spore counts suggest that there is no longer a seasonal cycle for N. ceranae and that it is found year round with little variation in infection intensity among months. Our goal was to determine whether infection levels differ in bees collected from different areas of the hive and if there may be seasonal differences in N. ceranae infections. A multiplex species-specific real-time PCR assay was used for the detection and quantification of N. ceranae. Colonies were sampled monthly from September 2009-2010 by collecting workers from honey supers, the fringe of the brood nest, and the brood nest. We found that all bees sampled were infected with N. ceranae and that there was no significant difference in infection levels among the different groups of bees sampled (P=0.74). However, significant differences in colony infection levels were found at different times of the year (P<0.01) with the highest levels in April-June and lower levels in the fall and winter. While our study was only performed for one year, it sheds light on the fact that there may be a seasonality to N. ceranae infections. Being able to predict future N. ceranae infections can be used to better advise beekeepers on N. ceranae management. © 2011 Elsevier Inc.
Sheldon J.,Protein Reference Unit |
Dellavance A.,Research and Development Division
Frontiers in Immunology | Year: 2015
Producing robust, certified, traceable reference material for autoantibody testing is a vital element in maintaining the validity of results that are generated in the daily clinical laboratory routine. This is a huge challenge because of the high number of variables involved in the detection and measurement of the autoantibodies. The production of such materials is time consuming and needs rigorous attention to detail; this is best achieved by an overarching independent body who will oversee the process in a "not for profit" manner. Much effort has been made to build international standards for quantitative and qualitative assays based on monoclonal antibodies, obtained from affinity purification and plasmapheresis. The big challenge is to respect individual differences in immune response to the same antigen. A promising ongoing initiative is the construction of pools with monospecific samples from different individuals. © 2015 Sheldon and Dellavance.