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Träfflista för sökning "WFRF:(Ahonen Lauri) "

Sökning: WFRF:(Ahonen Lauri)

  • Resultat 1-8 av 8
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1.
  • Alriksson-Schmidt, Ann I, et al. (författare)
  • CP-North: living life in the Nordic countries? : A retrospective register research protocol on individuals with cerebral palsy and their parents living in Sweden, Norway, Denmark, Finland and Iceland
  • 2019
  • Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 9:10
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: Cerebral palsy (CP) is one of the most common neurodevelopmental disabilities. Yet, most individuals with CP are adults. How individuals with CP fare in terms of health, quality of life (QoL), education, employment and income is largely unknown. Further, little is known about the effects of having a child with CP on the parents. The Nordic countries are known for their strong welfare systems, yet it is unknown to what extent the added burden related to disability is actually compensated for. We will explore how living with CP affects health, QoL, healthcare utilisation, education, labour market outcomes, socioeconomic status and mortality throughout the lifespan of individuals with CP and their parents. We will also investigate if these effects differ between subgroups, within and across the Nordic countries. METHODS AND ANALYSES: CP-North is a multidisciplinary 4-year (1 August 2017 to 31 July 2021) register research project. The research consortium comprises researchers and users from Sweden, Norway, Denmark, Iceland and Finland. Data from CP registries and follow-up programmes, or cohorts of individuals with CP, will be merged with general national registries. All individual studies are structured under three themes: medical outcomes, social and public health outcomes, and health economics. Both case-control and cohort designs will be included depending on the particular research question. Data will be analysed in the individual countries and later merged across nations.ETHICS AND DISSEMINATION: The ethics approval processes in each individual country are followed. Findings will be published (open access) in international peer-reviewed journals in related fields. Updates on CP-North will be published online at http://rdi.arcada.fi/cpnorth/en/.
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2.
  • Beck, Lisa J., et al. (författare)
  • Differing Mechanisms of New Particle Formation at Two Arctic Sites
  • 2021
  • Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 48:4
  • Tidskriftsartikel (refereegranskat)abstract
    • New particle formation in the Arctic atmosphere is an important source of aerosol particles. Understanding the processes of Arctic secondary aerosol formation is crucial due to their significant impact on cloud properties and therefore Arctic amplification. We observed the molecular formation of new particles from low-volatility vapors at two Arctic sites with differing surroundings. In Svalbard, sulfuric acid (SA) and methane sulfonic acid (MSA) contribute to the formation of secondary aerosol and to some extent to cloud condensation nuclei (CCN). This occurs via ion-induced nucleation of SA and NH3 and subsequent growth by mainly SA and MSA condensation during springtime and highly oxygenated organic molecules during summertime. By contrast, in an ice-covered region around Villum, we observed new particle formation driven by iodic acid but its concentration was insufficient to grow nucleated particles to CCN sizes. Our results provide new insight about sources and precursors of Arctic secondary aerosol particles.
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3.
  • Huang, Wei, et al. (författare)
  • Potential pre-industrial–like new particle formation induced by pure biogenic organic vapors in Finnish peatland
  • 2024
  • Ingår i: Science Advances. - 2375-2548. ; 10:14
  • Tidskriftsartikel (refereegranskat)abstract
    • Pure biogenic new particle formation (NPF) induced by highly oxygenated organic molecules (HOMs) could be an important mechanism for pre-industrial aerosol formation. However, it has not been unambiguously confirmed in the ambient due to the scarcity of truly pristine continental locations in the present-day atmosphere or the lack of chemical characterization of NPF precursors. Here, we report ambient observations of pure biogenic HOM-driven NPF over a peatland in southern Finland. Meteorological decoupling processes formed an “air pocket” (i.e., a very shallow surface layer) at night and favored NPF initiated entirely by biogenic HOM from this peatland, whose atmospheric environment closely resembles that of the pre-industrial era. Our study sheds light on pre-industrial aerosol formation, which represents the baseline for estimating the impact of present and future aerosol on climate, as well as on future NPF, the features of which may revert toward pre-industrial–like conditions due to air pollution mitigation.
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4.
  • Junninen, Heikki, et al. (författare)
  • Terpene emissions from boreal wetlands can initiate stronger atmospheric new particle formation than boreal forests
  • 2022
  • Ingår i: Communications Earth and Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 3:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Aerosols and their interaction with clouds constitute the largest uncertainty in estimating the radiative forcing affecting the climate system. Secondary aerosol formation is responsible for a large fraction of the cloud condensation nuclei in the global atmosphere. Wetlands are important to the budgets of methane and carbon dioxide, but the potential role of wetlands in aerosol formation has not been investigated. Here we use direct atmospheric sampling at the Siikaneva wetland in Finland to investigate the emission of methane and volatile organic compounds, and subsequently formed atmospheric clusters and aerosols. We find that terpenes initiate stronger atmospheric new particle formation than is typically observed over boreal forests and that, in addition to large emissions of methane which cause a warming effect, wetlands also have a cooling effect through emissions of these terpenes. We suggest that new wetlands produced by melting permafrost need to be taken into consideration as sources of secondary aerosol particles when estimating the role of increasing wetland extent in future climate change.
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5.
  • Kontkanen, Jenni, et al. (författare)
  • What controls the observed size-dependency of the growth rates of sub-10 nm atmospheric particles?
  • 2022
  • Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2634-3606. ; :2, s. 449-468
  • Tidskriftsartikel (refereegranskat)abstract
    • The formation and growth of atmospheric particles involving sulfuric acid and organic vapors is estimated to have significant climate effects. To accurately represent this process in large-scale models, the correct interpretation of the observations on particle growth, especially below 10 nm, is essential. Here, we disentangle the factors governing the growth of sub-10 nm particles in the presence of sulfuric acid and organic vapors, using molecular-resolution cluster population simulations and chamber experiments. We find that observed particle growth rates are determined by the combined effects of (1) the concentrations and evaporation rates of the condensing vapors, (2) particle population dynamics, and (3) stochastic fluctuations, characteristic to initial nucleation. This leads to a different size-dependency of growth rate in the presence of sulfuric acid and/or organic vapors at different concentrations. Specifically, the activation type behavior, resulting in growth rate increasing with the particle size, is observed only at certain vapor concentrations. In our model simulations, cluster-cluster collisions enhance growth rate at high vapor concentrations and their importance is dictated by the cluster evaporation rates, which demonstrates the need for accurate evaporation rate data. Finally, we show that at sizes below ∼2.5-3.5 nm, stochastic effects can importantly contribute to particle population growth. Overall, our results suggest that interpreting particle growth observations with approaches neglecting population dynamics and stochastics, such as with single particle growth models, can lead to the wrong conclusions on the properties of condensing vapors and particle growth mechanisms.
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6.
  • Lehtipalo, Katrianne, et al. (författare)
  • Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors
  • 2018
  • Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 4:12
  • Tidskriftsartikel (refereegranskat)abstract
    • A major fraction of atmospheric aerosol particles, which affect both air quality and climate, form from gaseous precursors in the atmosphere. Highly oxygenated organic molecules (HOMs), formed by oxidation of biogenic volatile organic compounds, are known to participate in particle formation and growth. However, it is not well understood how they interact with atmospheric pollutants, such as nitrogen oxides (NOx) and sulfur oxides (SOx) from fossil fuel combustion, as well as ammonia (NH3) from livestock and fertilizers. Here, we show how NOx suppresses particle formation, while HOMs, sulfuric acid, and NH3 have a synergistic enhancing effect on particle formation. We postulate a novel mechanism, involving HOMs, sulfuric acid, and ammonia, which is able to closely reproduce observations of particle formation and growth in daytime boreal forest and similar environments. The findings elucidate the complex interactions between biogenic and anthropogenic vapors in the atmospheric aerosol system.
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7.
  • Sokka, Laura, et al. (författare)
  • Job burnout is associated with dysfunctions in brain mechanisms of voluntary and involuntary attention
  • 2016
  • Ingår i: Biological Psychology. - : Elsevier BV. - 0301-0511 .- 1873-6246. ; 117, s. 56-66
  • Tidskriftsartikel (refereegranskat)abstract
    • Individuals with job burnout symptoms often report having cognitive difficulties, but related electro-physiological studies are scarce. We assessed the impact of burnout on performing a visual task withvarying memory loads, and on involuntary attention switch to distractor sounds using scalp record-ings of event-related potentials (ERPs). Task performance was comparable between burnout and controlgroups. The distractor sounds elicited a P3a response, which was reduced in the burnout group. Thissuggests burnout-related deficits in processing novel and potentially important events during task per-formance. In the burnout group, we also observed a decrease in working-memory related P3b responsesover posterior scalp and increase over frontal areas. These results suggest that burnout is associated withdeficits in cognitive control needed to monitor and update information in working memory. Successfultask performance in burnout might require additional recruitment of anterior regions to compensate thedecrement in posterior activity.
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8.
  • Wagner, Robert, et al. (författare)
  • The role of ions in new particle formation in the CLOUD chamber
  • 2017
  • Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 17:24, s. 15181-15197
  • Tidskriftsartikel (refereegranskat)abstract
    • The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nanoparticle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e., in conditions in which neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.5 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion-ion recombination before they grew to 2.5 nm. At this size, more than 90% of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.5 nm. Observations at Hyytiala, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.
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  • Resultat 1-8 av 8

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