1,315 research outputs found

    Laboratory tests with Lepidoptera to assess non-target effects of Bt maize pollen: analysis of current studies and recommendations for a standardised design

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    Background and approach Common standards for laboratory studies of non-target organisms are recognised as prerequisite to assist the risk assessments regarding the evaluation of environmental effects of transgenic crops. Here, we provide specific recommendations significant for experimental procedures of laboratory studies to test potential adverse effects of Bt maize on larvae of non-target Lepidoptera. We searched and analysed both ecotoxicological test protocols for pesticides in the EU as well as the non-target tests with Lepidoptera applied in unpublished industry studies submitted officially by agro-companies for the GMO authorisation in Europe. Results The classical ecotoxicology protocols applied for testing pesticides could serve as general guidelines, but do not completely fit the specific and differing requirements for assessing non-target effects of transgenic crops. The analysis of the non-target studies submitted for the application of the cultivation of Bt maize in Europe revealed critical limitations, thus corroborating the urgent need for common quality criteria. Based on our evaluations, we identified several issues requiring harmonisation or standardisation of the experimental conditions and approach, e.g., the application of Bt maize pollen, synthetic toxins, the provided diet for larvae, experimental controls, magnitude and duration of exposure to Bt, relevant variables to be recorded, and sufficient statistical power. Conclusions Our recommendations should stimulate the development of precise guidance for the authorities, and support the operationalisation of the required laboratory tests for the evaluation of non-target effects of Bt maize pollen on non-target Lepidoptera, also contributing to standards of other ecotoxicity tests with Lepidoptera larvae, e.g., for pesticides.This article has been prepared as an outcome of the BfN research project “Basisdaten zur Effektbewertung verschiedener Bt-Toxine auf Schmetterlingslarven” (FKZ 3515890100)

    Nonparametric Information Geometry

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    The differential-geometric structure of the set of positive densities on a given measure space has raised the interest of many mathematicians after the discovery by C.R. Rao of the geometric meaning of the Fisher information. Most of the research is focused on parametric statistical models. In series of papers by author and coworkers a particular version of the nonparametric case has been discussed. It consists of a minimalistic structure modeled according the theory of exponential families: given a reference density other densities are represented by the centered log likelihood which is an element of an Orlicz space. This mappings give a system of charts of a Banach manifold. It has been observed that, while the construction is natural, the practical applicability is limited by the technical difficulty to deal with such a class of Banach spaces. It has been suggested recently to replace the exponential function with other functions with similar behavior but polynomial growth at infinity in order to obtain more tractable Banach spaces, e.g. Hilbert spaces. We give first a review of our theory with special emphasis on the specific issues of the infinite dimensional setting. In a second part we discuss two specific topics, differential equations and the metric connection. The position of this line of research with respect to other approaches is briefly discussed.Comment: Submitted for publication in the Proceedings od GSI2013 Aug 28-30 2013 Pari

    A process-based model of conifer forest structure and function with special emphasis on leaf lifespan

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    We describe the University of Sheffield Conifer Model (USCM), a process-based approach for simulating conifer forest carbon, nitrogen, and water fluxes by up-scaling widely applicable relationships between leaf lifespan and function. The USCM is designed to predict and analyze the biogeochemistry and biophysics of conifer forests that dominated the ice-free high-latitude regions under the high pCO2 “greenhouse” world 290–50 Myr ago. It will be of use in future research investigating controls on the contrasting distribution of ancient evergreen and deciduous forests between hemispheres, and their differential feedbacks on polar climate through the exchange of energy and materials with the atmosphere. Emphasis is placed on leaf lifespan because this trait can be determined from the anatomical characteristics of fossil conifer woods and influences a range of ecosystem processes. Extensive testing of simulated net primary production and partitioning, leaf area index, evapotranspiration, nitrogen uptake, and land surface energy partitioning showed close agreement with observations from sites across a wide climatic gradient. This indicates the generic utility of our model, and adequate representation of the key processes involved in forest function using only information on leaf lifespan, climate, and soils

    Wnt secretion and gradient formation.

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    Concentration gradients formed by the lipid-modified morphogens of the Wnt family are known for their pivotal roles during embryogenesis and adult tissue homeostasis. Wnt morphogens are also implicated in a variety of human diseases, especially cancer. Therefore, the signaling cascades triggered by Wnts have received considerable attention during recent decades. However, how Wnts are secreted and how concentration gradients are formed remains poorly understood. The use of model organisms such as Drosophila melanogaster has provided important advances in this area. For instance, we have previously shown that the lipid raft-associated reggie/flotillin proteins influence Wnt secretion and spreading in Drosophila. Our work supports the notion that producing cells secrete Wnt molecules in at least two pools: a poorly diffusible one and a reggie/flotillin-dependent highly diffusible pool which allows morphogen spreading over long distances away from its source of production. Here we revise the current views of Wnt secretion and spreading, and propose two models for the role of the reggie/flotillin proteins in these processes: (i) reggies/flotillins regulate the basolateral endocytosis of the poorly diffusible, membrane-bound Wnt pool, which is then sorted and secreted to apical compartments for long-range diffusion, and (ii) lipid rafts organized by reggies/flotillins serve as "dating points" where extracellular Wnt transiently interacts with lipoprotein receptors to allow its capture and further spreading via lipoprotein particles. We further discuss these processes in the context of human breast cancer. A better understanding of these phenomena may be relevant for identification of novel drug targets and therapeutic strategies

    Longitudinal changes of mental health problems in children and adolescents treated in a primary care-based health-coaching programme – results of the PrimA-QuO cohort study

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    BACKGROUND: In Germany, 19.1% of boys and 14.5% of girls are affected by mental health problems (MHP). Paediatricians are usually the first in line to be contacted but they often do not feel adequately trained to diagnose and treat MHP in primary care. A major statutory health insurance fund introduced a health coaching (HC) programme to strengthen primary care consultation for MHP. The HC includes a training concept for paediatricians, standardised guidelines for actions and additional payments. The aim of this study was to investigate the potential effects of the HC programme on the change of MHP in children and adolescents. METHODS: A prospective cohort study was conducted in Bavaria, Germany, in 2018 and 2019. Data were collected at 2 points 1 year apart using an online questionnaire. Parents of patients with developmental disorder of speech and language, head/abdominal pain, conduct disorder or non-organic enuresis were approached by their health insurance. Families treated according to the HC programme form the intervention group while all others serve as controls. MHP was assessed using the Strengths and Difficulties Questionnaire (SDQ) as a child self-assessment (SDQ-S)/or external assessment by parents (SDQ-P). Determinants of SDQ total score were analysed using linear mixed effects models. RESULTS: Cross-sectional (n = 1090) and longitudinal analyses (n = 599) were performed. At baseline, a total of 23.5% had an SDQ total score “at risk” (SDQ-S > 15/SDQ-P > 13). There were no significant differences between intervention and controls. After full adjustment for all potential confounders, higher SDQ scores indicating more problems were significantly associated with male sex (2.000, p < 0.001) whereas a high parental education level was significantly associated with decreased SDQ scores (-2.127, p =0.034). There was a significant improvement in the control group over time (-0.814, p = 0.001) while the SDQ scores in the intervention group remained stable (-0.012, p = 0.020). CONCLUSION: This evaluation of the HC programme could not prove a clinically relevant intervention’s effect on the MHP developmental course. Nevertheless, (HC) paediatricians have crucial potential to improve the care of MHP patients. Targeting families with less access to support measures might help reduce the burden of MHP and be a step towards continuous improvement of care. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12875-022-01780-1

    Regularizing transformations of polygons

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