Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
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Tore SkrøppaAbstract
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Emma Brunberg Ildri Kristine Bergslid Knut Egil Bøe Kristin SørheimAbstract
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Levan Elbakidze Rodolfo M. Jr. NaygaAbstract
In the context of testing the construct validity of stated preference studies, some researchers advocate the use of an “adding-up test” designed to gauge whether elicited values are sufficiently sensitive to a change in the scope (i.e. size) of a good. Crucial to the applicability of this test in practice, which relies on endowing a subsample of respondents with a good free of charge, is that the income effects due to endowment are negligible. In this study, we apply the adding-up test in an experimental value elicitation format to examine the potential effect of endowment as part of the test design on the adding-up property of elicited values. The results show that the adding-up property can be affected by free provision of part of the bundle.
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Estimates of stand averages are needed by forest management for planning purposes. In forest enterprise inventories supported by remotely sensed auxiliary data, these estimates are typically derived exclusively from a model that does not consider stand effects in the study variable. Variance estimators for these means may seriously underestimate uncertainty, and confidence intervals may be too narrow when a model used for computing a stand mean omits a nontrivial stand effect in one or more of the model parameters, a nontrivial spatial distance dependent autocorrelation in the model residuals, or both. In simulated sampling from 36 populations with stands of different sizes and differing with respect to (i) the correlation between a study variable (Y) and two auxiliary variables (X), (ii) the magnitude of stand effects in the intercept of a linear population model linking X to Y, and (iii) a first-order autoregression in Y and X, we learned that none of the tested designs provided reliable estimates of the within-stand autocorrelation among model residuals. More-reliable estimates were possible from stand-wide predictions of Y. The anticipated bias in an estimated autoregression parameter had a modest influence on estimates of variance and coverage of nominal 95% confidence intervals for a synthetic stand mean.
Authors
Linda Meyer-Veltrup Christian Brischke Gry Alfredsen Miha Humar Per Otto Flæte Tord Isaksson Pia Larsson Brelid Mats Westin Jöran JermerAbstract
Comprehensive approaches to predict performance of wood products are requested by international standards, and the first attempts have been made in the frame of European research projects. However, there is still an imminent need for a methodology to implement the durability and moisture performance of wood in an engineering design method and performance classification system. The aim of this study was therefore to establish an approach to predict service life of wood above ground taking into account the combined effect of wetting ability and durability data. A comprehensive data set was obtained from laboratory durability tests and still ongoing field trials in Norway, Germany and Sweden. In addition, four different wetting ability tests were performed with the same material. Based on a dose– response concept, decay rates for specimens exposed above ground were predicted implementing various indicating factors. A model was developed and optimised taking into account the resistance of wood against soft, white and brown rot as well as relevant types of water uptake and release. Decay rates from above-ground field tests at different test sites in Norway were predicted with the model. In a second step, the model was validated using data from laboratory and field tests performed in Germany and Sweden. The model was found to be fairly reliable, and it has the advantage to get implemented into existing engineering design guidelines. The approach at hand might furthermore be used for implementing wetting ability data into performance classification as requested by European standardisation bodies.
Authors
Gordon J. McDougall J. William Allwood Gema Pereira-Caro Emma M. Brown Cheryl Latimer Gary Dobson Derek Stewart Nigel G. Ternan Roger Lawther Gloria O'Connor Ian Rowland Alan Crozier Chris I.R. GillAbstract
The beneficial effects of consumption of berry fruits on a range of chronic diseases has been attributed (at least in part) to the presence of unique phytochemicals. Recently, we identified novel ursolic acid-based triterpenoid glycosides (TTPNs) in raspberry fruit and demonstrated their survival in human ileal fluids after feeding which confirmed their colon-availability in vivo. In this paper, in vitro digestion studies demonstrated that certain TTPNs were stable under gastrointestinal conditions and confirmed that these components may have been responsible for bioactivity noted in previous studies. Sequential extractions of raspberry puree, isolated seeds and unseeded puree showed that certain TTPN components (e.g. peak T1 m/z 679, and T2 m/z 1358) had different extractabilities in water/solvent mixes and were differentially associated with the seeds. Purified seed TTPNs (mainly T1 and T2) were shown to be anti-genotoxic in HT29 and CCD841 cell based in vitro colonocyte models. Further work confirmed that the seeds contained a wider range of TTPN-like components which were also differentially extractable in water/solvent mixes. This differential extractability could influence the TTPN composition and potential bioactivity of the extracts. There was considerable variation in total content of TTPNs (∼3-fold) and TTPN composition across 13 Rubus genotypes. Thus, TTPNs are likely to be present in raspberry juices and common extracts used for bioactivity studies and substantial variation exists in both content and composition due to genetics, tissue source or extraction conditions, which may all affect observed bioactivity.
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Therese With BergeAbstract
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