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Sökning: WFRF:(Ólafsdóttir Kristín) > (2019)

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1.
  • Brönnimann, Stefan, et al. (författare)
  • Unlocking Pre-1850 Instrumental Meteorological Records : A Global Inventory
  • 2019
  • Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 100:12, s. ES389-ES413
  • Tidskriftsartikel (refereegranskat)abstract
    • Instrumental meteorological measurements from periods prior to the start of national weather services are designated early instrumental data. They have played an important role in climate research as they allow daily to decadal variability and changes of temperature, pressure, and precipitation, including extremes, to be addressed. Early instrumental data can also help place twenty-first century climatic changes into a historical context such as defining preindustrial climate and its variability. Until recently, the focus was on long, high-quality series, while the large number of shorter series (which together also cover long periods) received little to no attention. The shift in climate and climate impact research from mean climate characteristics toward weather variability and extremes, as well as the success of historical reanalyses that make use of short series, generates a need for locating and exploring further early instrumental measurements. However, information on early instrumental series has never been electronically compiled on a global scale. Here we attempt a worldwide compilation of metadata on early instrumental meteorological records prior to 1850 (1890 for Africa and the Arctic). Our global inventory comprises information on several thousand records, about half of which have not yet been digitized (not even as monthly means), and only approximately 20% of which have made it to global repositories. The inventory will help to prioritize data rescue efforts and can be used to analyze the potential feasibility of historical weather data products. The inventory will be maintained as a living document and is a first, critical, step toward the systematic rescue and reevaluation of these highly valuable early records. Additions to the inventory are welcome.
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2.
  • Leander, Jacob, 1987, et al. (författare)
  • Parameter Estimation for Nonlinear Mixed Effects Models Implemented in Mathematica
  • 2019
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In many applications within biology and medicine, measurements are gathered from several entities in the same experiment. This could for example be patients exposed to a treatment or cells measured after stimuli. To characterize the variability in response between entities, the nonlinear mixed effects (NLME) model is a suitable statistical model. An NLME model enables quantification of both within- and between subject variability. The parameter estimation in NLME models is not straightforward, due to the intractable expression of the likelihood function. In this work we present a Mathematica package for parameter estimation in NLME models where the longitudinal model is defined by differential equations. The parameter estimation problem is solved by the first-order conditional estimation (FOCE) method with exact gradients. The package is demonstrated using data from a simulated drug concentration model.
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3.
  • Sator, Lea, et al. (författare)
  • Overdiagnosis of COPD in Subjects With Unobstructed Spirometry A BOLD Analysis
  • 2019
  • Ingår i: Chest. - : Elsevier BV. - 0012-3692 .- 1931-3543. ; 156:2, s. 277-288
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: There are several reports on underdiagnosis of COPD, while little is known about COPD overdiagnosis and overtreatment. We describe the overdiagnosis and the prevalence of spirometrically defined false positive COPD, as well as their relationship with overtreatment across 23 population samples in 20 countries participating in the BOLD Study between 2003 and 2012.METHODS: A false positive diagnosis of COPD was considered when participants reported a doctor's diagnosis of COPD, but postbronchodilator spirometry was unobstructed (FEV1/FVC > LLN). Additional analyses were performed using the fixed ratio criterion (FEV1/FVC < 0.7).RESULTS: Among 16,177 participants, 919 (5.7%) reported a previous medical diagnosis of COPD. Postbronchodilator spirometry was unobstructed in 569 subjects (61.9%): false positive COPD. A similar rate of overdiagnosis was seen when using the fixed ratio criterion (55.3%). In a subgroup analysis excluding participants who reported a diagnosis of "chronic bronchitis" or "emphysema" (n = 220), 37.7% had no airflow limitation. The site-specific prevalence of false positive COPD varied greatly, from 1.9% in low- to middle-income countries to 4.9% in high-income countries. In multivariate analysis, overdiagnosis was more common among women, and was associated with higher education; former and current smoking; the presence of wheeze, cough, and phlegm; and concomitant medical diagnosis of asthma or heart disease. Among the subjects with false positive COPD, 45.7% reported current use of respiratory medication. Excluding patients with reported asthma, 34.4% of those with normal spirometry still used a respiratory medication.CONCLUSIONS: False positive COPD is frequent. This might expose nonobstructed subjects to possible adverse effects of respiratory medication.
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4.
  • Sverdrup, Harald, et al. (författare)
  • The WORLD6 Integrated System Dynamics Model: Examples of Results from Simulations
  • 2019
  • Ingår i: Progress Towards the Resource Revolution. - 9783952140987 ; , s. 68-76
  • Bokkapitel (refereegranskat)abstract
    • The WORLD6 model is a fully integrated dynamic world systems model. It includes a biophysical global economic model, based on first principles of physics and thermodynamics, forcing it to be fully consistent with the underlying mass- and energy balances. The WORLD6 model first creates value from extraction of natural resources, input of human labour, the efficiency effect of mechanization and automation, the effect of innovation and their use in manufacturing of goods and services, and the secondly does monetization through market mechanisms and debt financing. The model includes 7 different capital stocks for: (1) industrial resource extraction, (2) industrial manufacture, (3) social service capital, (4) agricultural capital for land use and food production, (5) military capital, (6) speculative capital tied up in derivatives, real estate, consumer credits, (7) criminal or illegal capital. There are 3 different debt pools; (1) general, (2) speculative and (3) pensions. These are all linked through a number of feedbacks in the system to resource extraction, energy production, population dynamics, food production and phosphorus extraction, manufacture of consumer goods and services. The WORLD6 model connects to environmental pollution with feedbacks and inputs to human health and climate change inside the model. The model includes money flows, stocks as well as debt dynamics and how this is connected to the capital base and the governance. The WORLD6 model has earlier been extensively tested on natural resource extraction rates, resource ore grades, supply volumes and market price for resources with very good success. The WORLD6 model system was tested in its economic aspects against observed GDP for the period 1850 to 2015 and GDP per capita, commodity prices, extraction rates and resource supply rates with good success. These results were obtained from first principles only and without calibrating the model to any type of data time-series.
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