4,909 research outputs found

    John Aito Pihlainen (1926-1964)

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    John Aito Pihlainen, civil engineer and a Fellow of the Arctic Institute since 1960, died suddenly in Ottawa in January of this year. He was born in Finland and emigrated to Canada with his parents in 1928. In 1950 he obtained his B.Eng. degree at McGill University and his M.Sc. at Purdue University two years later. He joined the Division of Building Research of the National Research Council in 1950 and pioneered the Division's investigations of permafrost and associated construction problems in northern Canada, beginning with a survey in 1950 of the construction and performance of buildings in the Mackenzie River valley. The following year he worked again in the Mackenzie Valley with an expedition examining the applicability of air photo interpretation methods for engineering site surveys in permafrost areas. In 1952 he established the Division's Northern Research Station at Norman Wells, N.W.T. from which numerous permafrost field projects were carried out in the Mackenzie Valley over a number of years. The Aklavik Relocation Survey of 1954 took him and his colleagues to the Mackenzie Delta where he was in charge of permafrost investigations to select a new townsite. For the next few years he was closely associated with the varied and comprehensive permafrost engineering studies being carried out by the Division of Building Research at Inuvik using this new town as a field laboratory. He also carried out field investigations in other parts of Canada's permafrost region and during his ten years with the National Research Council he became widely known for his broad knowledge of permafrost and associated engineering problems, and development of the philosophy of carefully executed site investigations prior to construction. In December 1960 he left the National Research Council and entered into private practice as an arctic consulting engineer based in Ottawa. During the three years prior to his death he was engaged in various engineering projects throughout northern Canada. Through his field work and many published papers he made notable contributions to the advancement of engineering site investigations and construction in permafrost areas. John Pihlainen was universally liked and respected for his practical approach mixed with an unusual sense of good humour. By many people living in the North, he was affectionately known as "Johnny Permafrost". His unexpected and tragic death cut short a successful career which had promised to add many more notable contributions to the development of Canada's permafrost region

    Shades of Grey: Ethical Dilemmas

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    The SF36 as an outcome measure of services for end stage renal failure

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    OBJECTIVE: —To evaluate the use of the short form 36 (SF36) as a measure of health related quality of life of patients with end stage renal failure, document the results, and investigate factors, including mode of treatment, which may influence it. DESIGN: Cross sectional survey of patients with end stage renal failure, with the standard United Kingdom version of the SF36 supplemented by specific questions for end stage renal failure. SETTING: A teaching hospital renal unit. Subjects and methods—660 patients treated at the Sheffield Kidney Institute by haemodialysis, peritoneal dialysis, and transplantation. Internal consistency, percentage of maximal or minimal responses, SF36 scores, effect sizes, correlations between independent predictor variables and individual dimension scores of the SF36. Multiple regression analysis of the SF36 scores for the physical functioning, vitality, and mental health dimensions against treatment, age, risk (comorbidity) score, and other independent variables. RESULTS: A high response rate was achieved. Internal consistency was good. There were no floor or ceiling effects other than for the two “role” dimensions. Overall health related quality of life was poor compared with the general population. Having a functioning transplant was a significant predictor of higher score in the three dimensions (physical functioning, vitality, and mental health) for which multiple regression models were constructed. Age, sex, comorbidity, duration of treatment, level of social and emotional support, household numbers, and hospital dialysis were also (variably) significant predictors. CONCLUSIONS: The SF36 is a practical and consistent questionnaire in this context, and there is evidence to support its construct validity. Overall the health related quality of life of these patients is poor, although transplantation is associated with higher scores independently of the effect of age and comorbidity. Age, comorbidity, and sex are also predictive of the scores attained in the three dimensions studied. Further studies are required to ascertain whether altering those predictor variables which are under the influence of professional carers is associated with changes in health related quality of life, and thus confirm the value of this outcome as a measure of quality of care

    Approaches to providing missing transfer parameter values in the ERICA Tool: how well do they work?

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    A required parameter for the ERICA Tool is the concentration ratio (CR), which is used to describe the transfer from environmental media to a range of organisms. For the original parameterisation of the ERICA Tool, 60% of these values were derived using a variety of extrapolation approaches, including the application of allometric models, the use of values for a similar organism or element with similar biogeochemical behaviour and the use of values from a different ecosystem. Although similar approaches are applied in other assessment systems, there has been little attempt to see how well these approaches perform. In this paper, CR values in the ERICA Tool derived using extrapolation approaches are compared to more recently available empirical data from the IAEA wildlife transfer database. The primary purpose of the default CR database in the ERICA Tool, and other models, is to enable the user to conduct conservative screening assessments. Conservatism was therefore introduced to the analyses by selecting the 95th percentile CR values for subsequent calculations. The extrapolation methodologies are not guaranteed to provide conservative estimates of empirical 95th percentile CRs. For the terrestrial ecosystem, the extrapolation methods provide underpredictions of empirical 95th percentiles as often as they produce overpredictions. In a few cases the underestimation of CR values, when considering all ecosystems, is substantial - by orders of magnitude - which is clearly unacceptable for a screening assessment. Thus, although extrapolation approaches will remain an essential component of screening assessments in the future, because data gaps will always be present, diligence is important in their application. Finally, by synthesizing the results from the current analyses and through other considerations, some recommendations are provided with regards to modifying the original guidance on use of extrapolation approaches in the ERICA Tool

    Exploring taxonomic and phylogenetic relationships to predict radiocaesium transfer to marine biota

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    One potentially useful approach to fill data gaps for concentration ratios, CRs, is based upon the hypothesis that an underlying taxonomic and/or phylogenetic relationship exists for radionuclide transfer. The objective of this study was to explore whether these relationships could be used to explain variation in the transfer of radiocaesium to a wide range of marine organisms. CR data for 137Cs were classified in relation to taxonomic family, order, class and phylum. A Residual Maximum Likelihood (REML) mixed-model regression modelling approach was adopted. The existence of any patterns were then explored using phylogenetic trees constructed with mitochondrial COI gene sequences from various biota groups and mapping the REML residual means onto these trees. A comparison of the predictions made using REML with blind datasets allowed the efficacy of the procedure to be tested. The only significant correlation between predicted and measured activity concentrations was revealed at the taxonomic level of order when comparing REML analysis output with data from the Barents Sea Region. For this single case a correlation 0.80 (Spearman rank) was derived which was significant at the 0.01 level (1-tailed test) although this was not the case once a (Bonferroni) correction was applied. The application of the REML approach to marine datasets has met with limited success, and the phylogenetic trees illustrate complications of using predictions based on values from different levels of taxonomic organization, where predicted values for the order level can mask the values at lower taxonomic levels. Any influence of taxonomy and phylogeny on transfer is not immediately conspicuous and categorizing marine organisms in this way is limited in providing a potentially robust prognostic extrapolation tool. Other factors may plausibly affect transfer to a much greater degree in marine systems, such as quite diverse life histories and different diets, which may confound any phylogenetic pattern

    Applying process-based models to the Borssele scenario

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    The objective of this paper is to consider the implications of employing process-based models on predictions for radionuclide activity concentrations in grass and cow milk. The FDMT (Food Chain and Dose Module for Terrestrial Pathways as used in the JRODOS and ARGOS decision support systems) model has been transferred to a modelling platform enabling sub-models to be modified and replaced. Primarily, this has involved invoking process-based models for 137Cs and 90Sr that account for soil chemistry in simulating bioavailability and plant transfer. The implementation of such models can lead to quite dramatic differences in predicted activity concentrations of radionuclides in grass and milk compared to a default FDMT set-up for time periods later than a few weeks post deposition. Considering transfer within a spatial context, by combining information from the outputs of process-based models with illustrative soil maps, leads to the observation that the most elevated 137Cs and 90Sr concentrations in grass and milk might not necessarily occur in areas where deposition is highest. Not accounting for soil type when modelling food chain transfer might lead to the sub-optimal allocation of resources or misidentification of the most vulnerable areas in the long-term after an accidental release

    Maternal obesity is associated with the formation of small dense LDL and hypoadiponectinemia in the third trimester

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    Context: Maternal obesity is associated with high plasma triglyceride, poor vascular function, and an increased risk for pregnancy complications. In normal-weight pregnant women, higher triglyceride is associated with increased small, dense low-density lipoprotein (LDL). Hypothesis: In obese pregnancy, increased plasma triglyceride concentrations result in triglyceride enrichment of very low-density lipoprotein-1 particles and formation of small dense LDL via lipoprotein lipase. Design: Women (n = 55) of body mass index of 18–46 kg/m2 were sampled longitudinally at 12, 26, and 35 weeks' gestation and 4 months postnatally. Setting: Women were recruited at hospital antenatal appointments, and study visits were in a clinical research suite. Outcome Measures: Plasma concentrations of lipids, triglyceride-rich lipoproteins, lipoprotein lipase mass, estradiol, steroid hormone binding globulin, insulin, glucose, leptin, and adiponectin were determined. Results: Obese women commenced pregnancy with higher plasma triglyceride, reached the same maximum, and then returned to higher postnatal levels than normal-weight women. Estradiol response to pregnancy (trimester 1–3 incremental area under the curve) was positively associated with plasma triglyceride response (r2 adjusted 25%, P < .001). In the third trimester, the proportion of small, dense LDL was 2-fold higher in obese women than normal-weight women [mean (SD) 40.7 (18.8) vs 21.9 (10.9)%, P = .014], and 35% of obese, 14% of overweight, and none of the normal-weight women displayed an atherogenic LDL subfraction phenotype. The small, dense LDL mass response to pregnancy was inversely associated with adiponectin response (17%, P = .013). Conclusions: Maternal obesity is associated with an atherogenic LDL subfraction phenotype and may provide a mechanistic link to poor vascular function and adverse pregnancy outcome

    Charge-density waves in one-dimensional Hubbard superlattices

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    We study the formation of charge density waves (CDW's) in one-dimensional Hubbard superlattices, modeled by a repeated pattern of repulsive (U>0) and free (U=0) sites. By means of Lanczos diagonalizations for the ground state, we calculate the charge structure factor. Our results show that while the superlattice structure affects the modulation of the charge density waves, the periodicity can still be predicted through an effective density. We also show that, for a fixed repulsive layer thickness, the periodicity of the CDW is an oscillatory function of the free layer thickness.Comment: 4 pages, 4 figure

    A new version of the ERICA tool to facilitate impact assessments of radioactivity on wild plants and animals

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    A new version of the ERICA Tool (version 1.2) was released in November 2014; this constitutes the first major update of the Tool since release in 2007. The key features of the update are presented in this article. Of particular note are new transfer databases extracted from an international compilation of concentration ratios (CRwo-media) and the modification of ‘extrapolation’ approaches used to select transfer data in cases where information is not available. Bayesian updating approaches have been used in some cases to draw on relevant information that would otherwise have been excluded in the process of deriving CRwo-media statistics. All of these efforts have in turn led to the requirement to update Environmental Media Concentration Limits (EMCLs) used in Tier 1 assessments. Some of the significant changes with regard to EMCLs are highlighte
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