16 research outputs found

    Five decades of terrestrial and freshwater research at Ny-Ã…lesund, Svalbard

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    For more than five decades, research has been conducted at Ny-Ã…lesund, in Svalbard, Norway, to understand the structure and functioning of High-Arctic ecosystems and the profound impacts on them of environmental change. Terrestrial, freshwater, glacial and marine ecosystems are accessible year-round from Ny-Ã…lesund, providing unique opportunities for interdisciplinary observational and experimental studies along physical, chemical, hydrological and climatic gradients. Here, we synthesize terrestrial and freshwater research at Ny-Ã…lesund and review current knowledge of biodiversity patterns, species population dynamics and interactions, ecosystem processes, biogeochemical cycles and anthropogenic impacts. There is now strong evidence of past and ongoing biotic changes caused by climate change, including negative effects on populations of many taxa and impacts of rain-on-snow events across multiple trophic levels. While species-level characteristics and responses are well understood for macro-organisms, major knowledge gaps exist for microbes, invertebrates and ecosystem-level processes. In order to fill current knowledge gaps, we recommend (1) maintaining monitoring efforts, while establishing a long-term ecosystem-based monitoring programme; (2) gaining a mechanistic understanding of environmental change impacts on processes and linkages in food webs; (3) identifying trophic interactions and cascades across ecosystems; and (4) integrating long-term data on microbial, invertebrate and freshwater communities, along with measurements of carbon and nutrient fluxes among soils, atmosphere, freshwaters and the marine environment. The synthesis here shows that the Ny-Ã…lesund study system has the characteristics needed to fill these gaps in knowledge, thereby enhancing our understanding of High-Arctic ecosystems and their responses to environmental variability and change

    De levende bodem in Globe

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    De samenleving herkent in de tegenwoordige tijd de bodem niet als "een levend fundament van ons bestaan", zoals dat door natuurwetenschappen wordt voorgestaan. Een van de manieren om begrip voor bodem in de samenleving te bevorderen is om de jeugd op school kennis te laten maken met biologische, chemische en fysische processen in de bode

    New reference charts for testicular volume in Dutch children and adolescents allow the calculation of standard deviation scores

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    Aim Accurate calculations of testicular volume standard deviation (SD) scores are not currently available. We constructed LMS-smoothed age-reference charts for testicular volume in healthy boys. Methods The LMS method was used to calculate reference data, based on testicular volumes from ultrasonography and Prader orchidometer of 769 healthy Dutch boys aged 6 months to 19 years. We also explored the association between testicular growth and pubic hair development, and data were compared to orchidometric testicular volumes from the 1997 Dutch nationwide growth study. Results The LMS-smoothed reference charts showed that no revision of the definition of normal onset of male puberty - from nine to 14 years of age - was warranted. In healthy boys, the pubic hair stage SD scores corresponded with testicular volume SD scores (r = 0.394). However, testes were relatively small for pubic hair stage in Klinefelter's syndrome and relatively large in immunoglobulin superfamily member 1 deficiency syndrome. Conclusion The age-corrected SD scores for testicular volume will aid in the diagnosis and follow-up of abnormalities in the timing and progression of male puberty and in research evaluations. The SD scores can be compared with pubic hair SD scores to identify discrepancies between cell functions that result in relative microorchidism or macroorchidism. ©2015 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd

    Impact of von Willebrand disease on health-related quality of life in a pediatric population

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    Item does not contain fulltextBACKGROUND: Von Willebrand disease (VWD) is the most frequent inherited bleeding disorder. Whether VWD is associated with health-related quality of life (HR-QoL) in children is unknown. OBJECTIVES: This nationwide cross-sectional study measured HR-QoL in children with moderate or severe VWD. Our primary aim was to compare HR-QoL of VWD patients with that of reference populations. Additionally, we studied the impact of bleeding phenotype and VWD type on HR-QoL. METHODS: HR-QoL was assessed with the Infant/Toddler QoL Questionnaire (0-5 years) and Child Health Questionnaire (6-15 years), and compared with reference population scores. Multivariate analysis was used to evaluate the influence of type of VWD and bleeding phenotype on HR-QoL scores. RESULTS: Preschool children (0-5 years, n = 46) with VWD had lower HR-QoL scores for general health perceptions and parental time than reference populations. School children (6-15 years, n = 87) with VWD had lower scores for physical functioning, role functioning - emotional/behavioral, general health perceptions, and physical summary. Type of VWD was associated with HR-QoL in school children for bodily pain, general health perceptions, parental emotion, family activities, and physical summary. Scores of children with type 3 VWD were, on average, 15 points lower than those of the reference population on the above-mentioned scales. A more severe bleeding phenotype was associated with a lower score on 11/15 physical, emotional and social scales. CONCLUSION: HR-QoL is lower in VWD children than in reference populations, in particular in school children. The negative impact of VWD is sensitive to type of VWD and bleeding phenotype; as well as physical scales, emotional and social scales are affected
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