32 research outputs found

    1.18 Linking protection goals to trigger values using compound specific properties: Chronic risks to bees

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    In the EFSA guidance document for the assessment of risk of plant protection products for bees the screening and tier I trigger for chronic risk to bees is linked to a trigger value which is intended to meet a certain level of protection. However, the methods used to derive the trigger of 0.03 do not take into account several factors including the shape and nature of the dose-repose used to generate the endpoint. This means that the resultant proposed trigger leads to a large over estimation of risk with a large number of compounds failing the risk assessment and being incorrectly identified as a higher chronic risk to honey bees. We analyzed the methods used in the selection of the trigger of 0.03 and propose simple adaptations to evaluate all active substances to the same level of protection by taking into account the type of endpoint and the dose response relationship. We found that by using the correct dose-response relationships we could accurately ensure that the desired level of protection was met. We checked our proposal using real-life examples of seven substances registered for use within the European Union and discuss how these proposals could be used to inform risk assessors and risk managers as well as potentially reducing the number of false positive and negatives in a risk assessment.In the EFSA guidance document for the assessment of risk of plant protection products for bees the screening and tier I trigger for chronic risk to bees is linked to a trigger value which is intended to meet a certain level of protection. However, the methods used to derive the trigger of 0.03 do not take into account several factors including the shape and nature of the dose-repose used to generate the endpoint. This means that the resultant proposed trigger leads to a large over estimation of risk with a large number of compounds failing the risk assessment and being incorrectly identified as a higher chronic risk to honey bees. We analyzed the methods used in the selection of the trigger of 0.03 and propose simple adaptations to evaluate all active substances to the same level of protection by taking into account the type of endpoint and the dose response relationship. We found that by using the correct dose-response relationships we could accurately ensure that the desired level of protection was met. We checked our proposal using real-life examples of seven substances registered for use within the European Union and discuss how these proposals could be used to inform risk assessors and risk managers as well as potentially reducing the number of false positive and negatives in a risk assessment

    1.6 Simple modelling approaches to refine exposure for bee risk assessment based on worst case assumptions

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    The risk assessment for plant protection products to bees has attracted a lot of attention over the past five years or more. Current estimates of exposure (e.g. EFSA, 2013) are based on 90th percentile concentrations of active substances present in pollen and nectar in the field. Although suitable for acute risks, in field concentrations are not suitable for chronic assessment especially for honey bees which feed from colony stores before making foraging flights or for larvae which are fed from in-hive food stores via nurse bees. Other areas of exposure such as to pollen and nectar in following crops or to guttation may also be better estimated by use of simple exposure models.We will present simple methods based worst case assumptions to model chronic adult and larval honey bee exposure to spray applications of plant protection products (PPP) which take into account in-hive storage of pollen and nectar and also approaches to model exposure levels in succeeding crops and guttation water.Case studies will be presented demonstrating how these worst case model exposure estimates can be used in refining the risk assessment for bees offering a robust, worst case and cost effective alternative to field studies. Having better robust modelled exposure estimates for in-hive food reserves can aid in the assessment of both single PPP stressors and interactions with multiple stressors (e.g. disease and Varroa mites).The risk assessment for plant protection products to bees has attracted a lot of attention over the past five years or more. Current estimates of exposure (e.g. EFSA, 2013) are based on 90th percentile concentrations of active substances present in pollen and nectar in the field. Although suitable for acute risks, in field concentrations are not suitable for chronic assessment especially for honey bees which feed from colony stores before making foraging flights or for larvae which are fed from in-hive food stores via nurse bees. Other areas of exposure such as to pollen and nectar in following crops or to guttation may also be better estimated by use of simple exposure models.We will present simple methods based worst case assumptions to model chronic adult and larval honey bee exposure to spray applications of plant protection products (PPP) which take into account in-hive storage of pollen and nectar and also approaches to model exposure levels in succeeding crops and guttation water.Case studies will be presented demonstrating how these worst case model exposure estimates can be used in refining the risk assessment for bees offering a robust, worst case and cost effective alternative to field studies. Having better robust modelled exposure estimates for in-hive food reserves can aid in the assessment of both single PPP stressors and interactions with multiple stressors (e.g. disease and Varroa mites)

    Robust State Estimation for T–S Fuzzy Markov Jump Systems

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    The problem of robust state estimation for a class of uncertain nonlinear systems with Markov jump is investigated. The uncertain nonlinear system under consideration is represented by the Takagi–Sugeno (T–S) fuzzy model because it is difficult to describe. Firstly, different from the traditional T–S fuzzy modeling method, the deviation of the linear system approaching a nonlinear system is considered, which is represented as a model error in system modeling. Secondly, through a robust state estimation method based on the sensitivity penalty, we develop a robust state estimator for linear subsystems, and the fuzzy robust state estimator is obtained by fuzzy rules. Thirdly, the stability and boundedness of the fuzzy robust state estimator are proved under the assumption conditions to ensure the reliability of the obtained estimator. Finally, some numerical examples are given to verify the effectiveness of the fuzzy robust state estimator

    Large-scale monitoring of effects of clothianidin-dressed oilseed rape seeds on pollinating insects in Northern Germany: effects on honey bees (Apis mellifera)

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    Possible effects of clothianidin seed-treated oilseed rape on honey bee colonies were investigated in a large-scale monitoring project in Northern Germany, where oilseed rape usually comprises 25–33 % of the arable land. For both reference and test sites, six study locations were selected and eight honey bee hives were placed at each location. At each site, three locations were directly adjacent to oilseed rape fields and three locations were situated 400 m away from the nearest oilseed rape field. Thus, 96 hives were exposed to fully flowering oilseed rape crops. Colony sizes and weights, the amount of honey harvested, and infection with parasites and diseases were monitored between April and September 2014. The percentage of oilseed rape pollen was determined in pollen and honey samples. After oilseed rape flowering, the hives were transferred to an extensive isolated area for post-exposure monitoring. Total numbers of adult bees and brood cells showed seasonal fluctuations, and there were no significant differences between the sites. The honey, which was extracted at the end of the exposure phase, contained 62.0–83.5 % oilseed rape pollen. Varroa destructor infestation was low during most of the course of the study but increased at the end of the study due to flumethrin resistance in the mite populations. In summary, honey bee colonies foraging in clothianidin seed-treated oilseed rape did not show any detrimental symptoms as compared to colonies foraging in clothianidin-free oilseed rape. Development of colony strength, brood success as well as honey yield and pathogen infection were not significantly affected by clothianidin seed-treatment during this study

    Design and Fabrication of Slidable Pedicle Screw Frame System for Surgery Therapy of Patients with Spinal Deformity in Growth Period

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    With the aim of preventing iatrogenic shot trunk, stiffness and rotation deformity caused by long-term fixation with usual locked pedicle screw system, a new kind of slidable pedicle screw frame system was designed and fabricated to treat patients with spinal deformity in the growth period. The frame was composed of slidable and locked pedicle screws, cross-links and double rods. The middle part of double rods was fixed with locked pedicle screws and two ends of them were with slidable ones. The spine longitudinal and transverse growth was not limited. 360 patients including 82 congenital scoliosis, 110 idiopathic scoliosis, 60 kyphosis, 44 spinal fractures and 63 spinal tumors or tuberculosis were treated. The average preoperative Cobb’s angle of scoliosis was 66.43°, post-operative one was 22.43°and lost 5° with average 14 months of following-up (6-37 months). The total longitudinal growth of adolescent spinal deformity was 86.4 cm (mean 0.9 cm). In conclusion, slidable pedicle screw frame system is successfully designed and fabricated, also stable and effective to correct the spinal deformities in adolescent growth period. The longitudinal and transverse spine growth of post-operation patients was not limited, and no complications such as stiffness, vertebrae rotation and crank shaft happened for post-operation patients
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