SARS-CoV-2:n tartunta ja leviäminen

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Crawling-induced floor dust resuspension affects the microbiota of the infant breathing zone

Background: Floor dust is commonly used for microbial determinations in epidemiological studies to estimate early-life indoor microbial exposures. Resuspension of floor dust and its impact on infant microbial exposure is, however, little explored. The aim of our study was to investigate how floor dust resuspension induced by an infant's crawling motion and an adult walking affects infant inhalation exposure to microbes. Results: We conducted controlled chamber experiments with a simplified mechanical crawling infant robot and an adult volunteer walking over carpeted flooring. We applied bacterial 16S rRNA gene sequencing and quantitative PCR to monitor the infant breathing zone microbial content and compared that to the adult breathing zone and the carpet dust as the source. During crawling, fungal and bacterial levels were, on average, 8- to 21-fold higher in the infant breathing zone compared to measurements from the adult breathing zone. During walking experiments, the increase in microbial levels in the infant breathing zone was far less pronounced. The correlation in rank orders of microbial levels in the carpet dust and the corresponding infant breathing zone sample varied between different microbial groups but was mostly moderate. The relative abundance of bacterial taxa was characteristically distinct in carpet dust and infant and adult breathing zones during the infant crawling experiments. Bacterial diversity in carpet dust and the infant breathing zone did not correlate significantly. Conclusions: The microbiota in the infant breathing zone differ in absolute quantitative and compositional terms from that of the adult breathing zone and of floor dust. Crawling induces resuspension of floor dust from carpeted flooring, creating a concentrated and localized cloud of microbial content around the infant. Thus, the microbial exposure of infants following dust resuspension is difficult to predict based on common house dust or bulk air measurements. Improved approaches for the assessment of infant microbial exposure, such as sampling at the infant breathing zone level, are needed.Peer reviewe

Fluorescence-based Real-Time Characterization of Bioaerosols

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Fluorescence-based Real-Time Characterization of Bioaerosols

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Electrical companies practices related to the local production of solar energy

Energiamurroksen myötä aurinkosähkön pientuotanto on kasvanut viimevuosina huomattavasti Suomessa. Kasvun oletetaan pysyvän korkeana myös tulevaisuudessa. Muutokset sähkön tuotannossa vaativat sähköyhtiöiltä toimimaan uusilla tavoilla, koska he joutuvat ottamaan huomioon sääriippuvaisten tuotantotapojen tuomia haasteita esimerkiksi sähköverkon suunnittelussa ja rakennuttamisessa. Sähköyhtiöiden paikallisen aurinkosähkön pientuotantoon liittyvien käytäntöjen selvittämiseksi teetettiin kyselytutkimus, joka lähetettiin kaikille Suomessa toimiville jakeluverkkoyhtiöille ja sähkönmyyjille. Kyselyn lähetystä ei rajattu vain tietyille sähköyhtiöille, jotta tulokset vastaisivat mahdollisimman todenmukaisesti koko Suomen eri sähköyhtiöiden käytäntöjä, ja verkkoon liitettyjen järjestelmien tietoja. Vastausten tuloksia verrataan muihin tutkimuksiin ja avoimiin lähteisiin. Tässä diplomityössä tunnistettiin aurinkosähköjärjestelmien tehoissa ja verkkoon liitetyssä pientuotannon kapasiteetissa tapahtuneet merkittävää kasvua viime vuosina. Jakeluverkkoyhtiöt osoittivat huolia tästä kasvusta. Jakeluverkkoyhtiöt olivat huolissaan aurinkosähkön aiheuttavan ongelmia sähkön laadussa ja palvelumaksujen nousemisessa. Suurin osa jakeluverkkoyhtiöistä olivat varautuneet aurinkosähkön pientuotannon kasvuun jollain tavoin. Sähköyhtiöiden käytännöissä huomattiin eroja. Kaikki sähköyhtiöt eivät tarjonneet samoja aurinkosähköön liittyviä palveluita. Paikallisen aurinkosähkön tuotannon vaikutusten seurannassa oli eroavaisuuksia eri sähköyhtiöiden välillä, ja eri sähköyhtiöt arvioivat aurinkosähkön pientuotannon vaikuttavan heidän toimintaansa eri lailla.Due to the energy transition, small-scale production of solar electricity has grown considerably in Finland in recent years. This growth is assumed to remain high in the future as well. Changes in electricity pro-duction require electricity companies to operate new ways, because they must consider the challenges related to intermitted energy production, for example, in the planning and construction of the electricity network. In order to find out the practices of electricity companies related to the small-scale production of local solar energy, a survey was commissioned and sent to all distribution network companies and electricity sellers operating in Finland. The survey was not limited to any group, so that the results correspond as accurately as possible to the practices of electricity companies in Finland, and to the solar energy systems that are connected to distribution network. The answers are compared to other studies and open sources. In this thesis, significant growth in the size of solar energy systems and the capacity of small-scale production connected to the grid was identified. Distribution network operators expressed concerns about this growth. The distribution network operators were worried that the in-crease of solar electricity would cause problems with the quality of electricity and that it would increase the electricity transmission costs. Most of the distribution network companies had prepared for the growth of small-scale production of solar energy in some way. Differences were identified in the practices of the electricity companies. Some companies did not offer the same services as others. There were differences in monitoring the effects of solar electricity between different electricity companies. Different companies also estimated in different ways how small-scale production of solar energy is going to affect their operations in the future

A matrix-free fixed-point iteration for inverting cascade impactor measurements with instrument's sensitivity kernels and hardware

This study focuses on advancing the inversion of aerosol data measured by a cascade impactor. Our aim is to find and validate a comprehensive and robust mathematical model for reconstructing a particle mass distribution. In this paper, we propose a fixed-point iteration as a method for inverting cascade impactor measurements with a relatively simple measurement hardware, which is not optimized for handling ad- vanced linear algebraic operations such as large matrices. We validate this iteration numerically against an iterative L1 norm regularized iterative alternating sequential inversion algorithm. In the numerical experiments, we investigate and compare a point-wise (matrix-free) and integrated kernel-based approach in inverting five dif- ferent aerosol mass concentration distributions based on simulated measurements and sensitivity kernel functions