1401. |
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1402. |
- Nieminen, Tuomo, et al.
(författare)
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Global analysis of continental boundary layer new particle formation based on long-term measurements
- 2018
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:19, s. 14737-14756
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric new particle formation (NPF) is an important phenomenon in terms of global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles, and growth rates in the size range of 10-25 nm using at least 1 year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability. At the measurement sites analyzed in this study, NPF occurs most frequently in March-May (on about 30 % of the days) and least frequently in December-February (about 10 % of the days). The median formation rate of 10 nm particles varies by about 3 orders of magnitude (0.01-10 cm(-3) s(-1)) and the growth rate by about an order of magnitude (1-10 nm h(-1)). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate among the different measurement sites, as well as among the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in North America, Asia, and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.
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1403. |
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1404. |
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1405. |
- Norström, Karin, et al.
(författare)
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External exposure and bioaccumulation of PCBs in humans living in a contaminated urban environment.
- 2010
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 36:8, s. 855-861
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Tidskriftsartikel (refereegranskat)abstract
- Humans are exposed to different mixtures of PCBs depending on the route of exposure. In this study we investigated the potential contribution of inhalation to the overall human exposure to PCBs in an urban area. For this purpose, the mechanistically based, non-steady state bioaccumulation model ACC-HUMAN was applied to predict the PCB body burden in an adult living in the Midwestern United States who eats a typical North American diet and inhales air contaminated with PCBs. Dietary exposure was estimated using measured data for eighteen PCB congeners in different food groups (fish, meat and egg, dairy products). Two scenarios for inhalation exposure were evaluated: one using air concentrations measured in Chicago, and a second using air measurements in a remote area on Lake Michigan, Sleeping Bear Dunes. The model predicted that exposure via inhalation increases the accumulated mass of PCBs in the body by up to 30% for lower chlorinated congeners, while diet is by far the dominant source of exposure for those PCB congeners that accumulate most in humans.
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1406. |
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1407. |
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1408. |
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1409. |
- Nutt, D, et al.
(författare)
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Establishing non-inferiority in treatment trials in psychiatry: guidelines from an Expert Consensus Meeting
- 2008
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Ingår i: Journal of psychopharmacology (Oxford, England). - : SAGE Publications. - 0269-8811 .- 1461-7285. ; 22:4, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- Comparing the efficacy of different treatments in psychiatry is difficult for many reasons, even when they are investigated in `head-to-head' studies. A consensus meeting was, therefore, held to produce best practice guidelines for such studies. This article presents the conclusions of this consensus and illustrates it using published data in the field of antidepressant treatment of generalized anxiety disorder.
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1410. |
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