Quantitative estimation of sampling uncertainties for mycotoxins in cereal shipments

Many countries receive shipments of bulk cereals from primary producers. There is a volume of work that is ongoing that seeks to arrive at appropriate standards for the quality of the shipments and the means to assess the shipments as they are out-loaded. Of concern are mycotoxin and heavy metal levels, pesticide and herbicide residue levels, and contamination by genetically modified organisms (GMOs). As the ability to quantify these contaminants improves through improved analytical techniques, the sampling methodologies applied to the shipments must also keep pace to ensure that the uncertainties attached to the sampling procedures do not overwhelm the analytical uncertainties. There is a need to understand and quantify sampling uncertainties under varying conditions of contamination. The analysis required is statistical and is challenging as the nature of the distribution of contaminants within a shipment is not well understood; very limited data exist. Limited work has been undertaken to quantify the variability of the contaminant concentrations in the flow of grain coming from a ship and the impact that this has on the variance of sampling. Relatively recent work by Paoletti et al. in 2006 [Paoletti C, Heissenberger A, Mazzara M, Larcher S, Grazioli E, Corbisier P, Hess N, Berben G, Lubeck PS, De Loose M, et al. 2006. Kernel lot distribution assessment (KeLDA): a study on the distribution of GMO in large soybean shipments. Eur Food Res Tech. 224:129–139] provides some insight into the variation in GMO concentrations in soybeans on cargo out-turn. Paoletti et al. analysed the data using correlogram analysis with the objective of quantifying the sampling uncertainty (variance) that attaches to the final cargo analysis, but this is only one possible means of quantifying sampling uncertainty. It is possible that in many cases the levels of contamination passing the sampler on out-loading are essentially random, negating the value of variographic quantitation of the sampling variance. GMOs and mycotoxins appear to have a highly heterogeneous distribution in a cargo depending on how the ship was loaded (the grain may have come from more than one terminal and set of storage silos) and mycotoxin growth may have occurred in transit. This paper examines a statistical model based on random contamination that can be used to calculate the sampling uncertainty arising from primary sampling of a cargo; it deals with what is thought to be a worst-case scenario. The determination of the sampling variance is treated both analytically and by Monte Carlo simulation. The latter approach provides the entire sampling distribution and not just the sampling variance. The sampling procedure is based on rules provided by the Canadian Grain Commission (CGC) and the levels of contamination considered are those relating to allowable levels of ochratoxin A (OTA) in wheat. The results of the calculations indicate that at a loading rate of 1000 tonnes h-1, primary sample increment masses of 10.6 kg, a 2000-tonne lot and a primary composite sample mass of 1900 kg, the relative standard deviation (RSD) is about 1.05 (105%) and the distribution of the mycotoxin (MT) level in the primary composite samples is highly skewed. This result applies to a mean MT level of 2 ng g-1. The rate of false-negative results under these conditions is estimated to be 16.2%. The corresponding contamination is based on initial average concentrations of MT of 4000 ng g-1 within average spherical volumes of 0.3m diameter, which are then diluted by a factor of 2 each time they pass through a handling stage; four stages of handling are assumed. The Monte Carlo calculations allow for variation in the initial volume of the MT-bearing grain, the average concentration and the dilution factor. The Monte Carlo studies seek to show the effect of variation in the sampling frequency while maintaining a primary composite sample mass of 1900 kg. The overall results are presented in terms of operational characteristic curves that relate only to the sampling uncertainties in the primary sampling of the grain. It is concluded that cross-stream sampling is intrinsically unsuited to sampling for mycotoxins and that better sampling methods and equipment are needed to control sampling uncertainties. At the same time, it is shown that some combination of crosscutting sampling conditions may, for a given shipment mass and MT content, yield acceptable sampling performance

The reliability of asset management regime of the SROH using air void content of asphalt mixtures

The comparison pairs of cores (each 100 mm apart) from 68 reinstatements sites from various parts of the UK revealed that, the compounding consequences of generic non-homogeneous characteristics of hand laid recipe mixed materials (specified in Specification for the Reinstatement of Openings in Highways (SROH)) and high likeliness of being biased during air void (AV) testing makes the coring method extremely unreliable with very low repeatability and reproducibility. The wide-ranging maximum density reported in every instance in the comparison pair coring experiments meaningfully rationalizes the distorted homogeneity of materials. Although not only maximum density but also bulk density of adjacent cores located only 100 mm apart were found to be varied in the case of every pair in this study. Furthermore, the in situ performance shown by from 50 reinstatements after experiencing 1.5–10 years real-life ageing from various parts of the UK predictably indicates that either the linkage between the reinstatement with non-compliant AV and its impact on footways durability is non-proven or the reported AV content is extremely over estimated. At 95% level of significance, there exists enough evidence to conclude that, due to high uncertainty, very low repeatability and reproducibility and poor reliability with high chances of bias, the assessment of hand laid reinstatement work by AV testing will expose both the contractor and the client to unacceptable risk. © 2017 Informa UK Limited, trading as Taylor & Francis Grou

An integrated view of data quality in Earth observation

Data quality is a difficult notion to define precisely, and different communities have different views and understandings of the subject. This causes confusion, a lack of harmonization of data across communities and omission of vital quality information. For some existing data infrastructures, data quality standards cannot address the problem adequately and cannot fulfil all user needs or cover all concepts of data quality. In this study, we discuss some philosophical issues on data quality. We identify actual user needs on data quality, review existing standards and specifications on data quality, and propose an integrated model for data quality in the field of Earth observation (EO). We also propose a practical mechanism for applying the integrated quality information model to a large number of datasets through metadata inheritance. While our data quality management approach is in the domain of EO, we believe that the ideas and methodologies for data quality management can be applied to wider domains and disciplines to facilitate quality-enabled scientific research

New developments with cold asphalt concrete binder course mixtures containing binary blended cementitious filler (BBCF)

A weakness in early strength and the need for longer curing times in the case of cold bituminous emulsion mixtures (CBEMs) compared to hot mix asphalt have been cited as barriers to the wider utilization of these mixtures. A binary blended filler material produced from high calcium fly ash (HCFA) and a fluid catalytic cracking catalyst (FC3R) was found to be very effective in providing microstructural integrity with a novel fast-curing cold asphalt concrete for the binder course (CACB) mixture. Balanced oxide compositions within the novel filler were identified as responsible for an enhanced hydration reaction, resulting in a very high early strength and a significant improvement in permanent deformation and fatigue resistance. Improved water sensitivity for progressive hydration with the new binary filler was also established while SEM analysis confirmed the formation of hydration products after various curing ages. © 2016 Elsevier Lt

The minimum energy expenditure shortest path method

This article discusses the addition of an energy parameter to the shortest path execution process; namely, the energy expenditure by a character during execution of the path. Given a simple environment in which a character has the ability to perform actions related to locomotion, such as walking and stair stepping, current techniques execute the shortest path based on the length of the extracted root trajectory. However, actual humans acting in constrained environments do not plan only according to shortest path criterion, they conceptually measure the path that minimizes the amount of energy expenditure. On this basis, it seems that virtual characters should also execute their paths according to the minimization of actual energy expenditure as well. In this article, a simple method that uses a formula for computing vanadium dioxide ($VO_2$) levels, which is a proxy for the energy expenditure by humans during various activities, is presented. The presented solution could be beneficial in any situation requiring a sophisticated perspective of the path-execution process. Moreover, it can be implemented in almost every path-planning method that has the ability to measure stepping actions or other actions of a virtual character

Health implications of PAH release from coated cast iron drinking water distribution systems in The Netherlands.

BACKGROUND: Coal tar and bitumen have been historically used to coat the insides of cast iron drinking water mains. Polycyclic aromatic hydrocarbons (PAHs) may leach from these coatings into the drinking water and form a potential health risk for humans. OBJECTIVE: We estimated the potential human cancer risk from PAHs in coated cast iron water mains. METHOD: In a Dutch nationwide study, we collected drinking water samples at 120 locations over a period of 17 days under various operational conditions, such as undisturbed operation, during flushing of pipes, and after a mains repair, and analyzed these samples for PAHs. We then estimated the health risk associated with an exposure scenario over a lifetime. RESULTS: During flushing, PAH levels frequently exceeded drinking water quality standards; after flushing, these levels dropped rapidly. After the repair of cast iron water mains, PAH levels exceeded the drinking water standards for up to 40 days in some locations. CONCLUSIONS: The estimated margin of exposure for PAH exposure through drinking water was > 10,000 for all 120 measurement locations, which suggests that PAH exposure through drinking water is of low concern for consumer health. However, factors that differ among water systems, such as the use of chlorination for disinfection, may influence PAH levels in other locations

Clinical and laboratory practice for lupus anticoagulant testing : an International Society of Thrombosis and Haemostasis Scientific and Standardization Committee survey

Background Current guidelines have contributed to more uniformity in the performance and interpretation of lupus anticoagulant (LA) testing. However, points to reconsider include testing for LA in patients on anticoagulation, cut-off values, and interpretation of results. Objectives The aim of this International Society of Thrombosis and Haemostasis Scientific and Standardization committee (ISTH SSC) questionnaire was to capture the spectrum of clinical and laboratory practice in LA detection, focusing on variability in practice, so that the responses could inform further ISTH SSC recommendations. Methods Members of the ISTH SSC on Lupus Anticoagulant/Antiphospholipid Antibodies and participants of the Lupus Anticoagulant/Antiphospholipid Antibodies Programme of the External quality Control of diagnostic Assays and Tests Foundation were invited to complete a questionnaire on LA testing that was placed on the ISTH website using RedCap, with data tallied using simple descriptive statistics. Results There was good agreement on several key recommendations in the ISTH and other guidelines on LA testing, such as sample processing, principles of testing, choice of tests, repeat testing to confirm persistent positivity and the use of interpretative reporting. However, the results highlight that there is less agreement on some other aspects, including the timing of testing in relation to thrombosis or pregnancy, testing in patients on anticoagulation, cut-off values, and calculation and interpretation of results. Conclusions Although some of the variability in practice in LA testing reflects the lack of substantive data to underpin evidence-based recommendations, a more uniform approach, based on further guidance, should reduce the inter-center variability of LA testing

Developing a Task Switching Training Game for Children With a Rare Genetic Syndrome Linked to Intellectual Disability

Background. The ability to rapidly switch between tasks is important in a variety of contexts. Training in task switching may be particularly valuable for children with intellectual disability (ID), specifically ID linked to genetic syndromes such as Prader-Willi syndrome (PWS). We have developed a cognitive training game for children with PWS and performed a pilot evaluation of the programme to inform future game development. Here, we describe and critically reflect on the development and pilot evaluation process.Methods. Several novel aspects of our approach are highlighted in this paper, including the involvement (in various roles) of children with a rare genetic syndrome (PWS) in the development and evaluation of the software (participatory design) and the development of a matched control, or placebo version of the game for use in the pilot evaluation.Results.Children with PWS were capable of contributing to the design and development of a cognitive training game in various roles. In the subsequent pilot evaluation, playing the active version of the game was associated with greater improvement in task switching performance than playing the matched control (placebo) version of the game. However, attrition was an issue during both the design phase and the pilot evaluation.Conclusions. The lessons learned from our work have relevance in a wide range of contexts, such as the development of future cognitive training games; the evaluation of serious games in general; and the involvement of end-users with cognitive disabilities and/or rare syndromes in the design and development of software

Identification of mass–spring–damper model of walking humans

Interaction of walking people with vibrating structures is known to be an important yet challenging phenomenon to simulate. Despite of its considerable effects on the structural response, no properly formulated and experimentally verified model currently exists to simulate this interaction in the vertical direction. This work uses a single-degree-of-freedom mass–spring–damper model of a walking human to simulate its interaction with a vibrating structure. Extensive frequency response function measurements were performed on a test structure that was occupied by more than a hundred test subjects walking in various group sizes and at different times in 23 tests. The identified modal properties of the occupied structure were used in three different identification procedures to estimate the parameters of the walking human model. A discrete model of human–structure system was used to simulate interaction of each walking person with the structure. The analysis identified the range of 2.75–3.00 Hz for the natural frequency and 27.5%–30% for the damping ratio of the model of a walking human, having constant mass of 70 kg. The extent of the experimental data and the measurement details, diversity of loading scenarios and consistency of the results of the different identification procedures, provided high level of confidence on the suggested parameters for the single-degree-of-freedom walking human model.UK Engineering and Physical Sciences Research Council (EPSRC