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Generalized Linear Modelling (generalized + linear_modelling)
Selected AbstractsVariation in litter under individual tree crowns: Implications for scattered tree ecosystemsAUSTRAL ECOLOGY, Issue 1 2010CHRIS MCELHINNY Abstract In forest ecosystems litter is usually assessed in terms of the average amount produced by the canopy. In scattered tree ecosystems this approach is problematic because the canopy is discontinuous and the spatial arrangement of litter highly variable. We addressed this problem by quantifying the spatial variation in litter load and litter composition associated with individual trees in a Eucalyptus melliodora , Eucalyptus blakelyi woodland. Litter was sampled under crowns and in grassland adjacent to 10 E. blakelyi and 10 E. melliodora trees ranging in diameter at breast height (dbh) from 14 to 129 cm. A total of 302 L samples were collected from these trees, at distances ranging from 0 to 42 m from main stem. The sampled litter loads ranged from 0.02 to 109.3 t ha,1 and were significantly higher under tree crowns than in grassland for litter and each component of litter (leaves, bark, fine twigs, coarse twigs). In particular, the mean litter load under tree crowns (12.5 t ha,1) was an order of magnitude higher than the mean litter load in grassland (1.27 t ha,1). There was a significant (P = 0.0103) positive relationship between mean litter load under the tree crown and dbh, indicating larger trees produced more litter per unit area of ground than smaller trees. Generalized Linear Modelling produced highly significant (P < 0.0001) models predicting the spatial variation in litter load and litter composition in terms of distance from main stem and dbh. Our models demonstrate gradients in litter load and composition under tree crowns. These gradients were most pronounced for the large trees in our study. The disproportionate input of litter and variety of litter components associated with large trees in our study supports their keystone role in scattered tree ecosystems and highlights the need to maintain these structures in agricultural landscapes. [source] Treatment of paediatric atopic dermatitis with pimecrolimus (Elidel®, SDZ ASM 981): impact on quality of life and health-related quality of lifeJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 3 2006SP McKenna Abstract Aim, To report on quality of life (QoL) and health-related quality of life (HRQL) impacts of pimecrolimus (Elidel®, Novartis A.G., Basel, Switzerland, SDZ ASM 981) 1% cream in the long-term treatment of paediatric atopic dermatitis. Methods, QoL and HRQL data are presented from two 12-month international clinical trials evaluating the efficacy and safety of pimecrolimus 1% cream. Both trials were randomized and double blinded and compared two treatment strategies, one involving the use of emollients, pimecrolimus and topical corticosteroids, the other is ,usual care' (emollients plus topical corticosteroids) with a vehicle cream to maintain study blinding. The first trial (the infant trial) involved patients between ages 3 months and 2 years, whereas the children trial included patients aged 2,17 years. In both trials, QoL of the affected child's parent was evaluated with the parent's index of quality of life in atopic dermatitis (PIQoL-AD). HRQL was assessed in the children trial only with the children's dermatology life quality index (CDLQI). QoL and HRQL assessments were conducted at baseline, 6 weeks, 6 months and 12 months. Results, Generalized linear modelling of PIQoL-AD scores at each post-baseline visit showed a greater impact on parent's QoL for pimecrolimus compared with control at all time-points in both trials. HRQL scores showed a greater improvement from baseline for children in the pimecrolimus group compared with those in the control group at all time-points. Conclusions,, The results show a beneficial impact of pimecrolimus on parents' QoL in paediatric atopic dermatitis, confirming findings from earlier shorter term trials. There was also a clear benefit to the HRQL of the children treated. [source] Generalized linear modelling in periglacial studies: terrain parameters and patterned groundPERMAFROST AND PERIGLACIAL PROCESSES, Issue 4 2004Miska Luoto Abstract Generalized linear models (GLM) are mathematical extensions of linear models. GLM models are more flexible and better suited for analysing relationships of spatial data, which can often be poorly represented by classical Gaussian distributions such as least-square-regression techniques. This paper demonstrates GLM model-building procedures step-by-step for the distribution and abundance of active patterned ground in northern Finland. The exercise is based on data from an area of 200,km2 (800 modelling squares of 0.25,km2). Both the distribution and abundance models clearly indicate an increasing activity of patterned ground with (1) increasing soil moisture and (2) proportion of concave topography. Activity decreases with increasing altitude. We conclude that GLM techniques combined with a geographic information system can play an important role in analysing and modelling periglacial data sets. Copyright © 2004 John Wiley & Sons, Ltd. [source] The Social Networks of People with Intellectual Disability Living in the Community 12 Years after Resettlement from Long-Stay HospitalsJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 4 2006Rachel Forrester-Jones Background, The social inclusion of people with intellectual disabilities presents a major challenge to services. As part of a 12-year follow up of people resettled from long-stay hospitals, the size of 213 individuals' social networks and the types of social support they received were investigated, as viewed by people with intellectual disabilities themselves. The types of support received in four different kinds of community accommodation were compared. Method, Individuals were interviewed and their social support networks mapped using a Social Network Guide developed for the study. Descriptive statistics were generated and comparisons made using generalized linear modelling. Results, The sample comprised 117 men (average age 51 years) and 96 women (average age 56 years). All but seven were White British, 92% were single and they had in general, mild to moderate intellectual disabilities. The average network size was 22 members (range 3,51). The mean density was 0.5. A quarter of all network members were other service users with intellectual disabilities and a further 43% were staff. Only a third of the members were unrelated to learning disability services. In general, the main providers of both emotional and practical support were staff, although these relationships were less likely to be described as reciprocal. Other people with intellectual disabilities were the second most frequent providers of all types of support. People in small group homes, hostels and supported accommodation were significantly more likely to report close and companiable relationships than those in residential and nursing homes, but they also reported a greater proportion of critical behaviour. Conclusions, The social networks revealed in this study are considerably larger than those of previous studies which have relied on staff reports, but findings about the generally limited social integration of people with intellectual disabilities are similar. A clearer policy and practice focus on the desirability of a range of different social contexts from which to derive potentially supportive network members is required so that people do not remain segregated in one area of life. [source] Developing a modern pollen,climate calibration data set for NorwayBOREAS, Issue 4 2010ANNE E. BJUNE Bjune, A. E., Birks, H. J. B., Peglar, S. M. & Odland, A. 2010: Developing a modern pollen,climate calibration data set for Norway. Boreas, Vol. 39, pp. 674,688. 10.1111/j.1502-3885.2010.00158.x. ISSN 0300-9483. Modern pollen,climate data sets consisting of modern pollen assemblages and modern climate data (mean July temperature and mean annual precipitation) have been developed for Norway based on 191 lakes and 321 lakes. The original 191-lake data set was designed to optimize the distribution of the lakes sampled along the mean July temperature gradient, thereby fulfilling one of the most critical assumptions of weighted-averaging regression and calibration and its relative, weighted-averaging partial least-squares regression. A further 130 surface samples of comparable taphonomy, taxonomic detail and analyst became available as a result of other projects. These 130 samples, all from new lakes, were added to the 191-lake data set to create the 321-lake data set. The collection and construction of these data sets are outlined. Numerical analyses involving generalized linear modelling, constrained ordination techniques, weighted-averaging partial least-squares regression, and two different cross-validation procedures are used to asses the effects of increasing the size of the calibration data set from 191 to 321 lakes. The two data sets are used to reconstruct mean July temperature and mean annual precipitation for a Holocene site in northwest Norway and a Lateglacial site in west-central Norway. Overall, little is to be gained by increasing the modern data set beyond about 200 lakes in terms of modern model performance statistics, but the down-core reconstructions show less between-sample variability and are thus potentially more plausible and realistic when based on the 321-lake data set. [source] | ||||||||||