Laser-probe analysis of modern electroacoustic microwave devices

In this thesis, devices based on surface acoustic waves (SAWs) and microelectromechanical systems (MEMS) are investigated using laser-probe measurements. The type of SAW and MEMS devices studied here are typically used, for example, in mobile phones as radio frequency components, such as filters and reference oscillators. The dissertation focuses on measuring and analyzing vibration fields in the devices using the scanning Michelson laser interferometer developed at TKK. The interferometer as such detects out-of-plane vibrations, i.e., vibrations perpendicular to the surface of the device, with minimum detectable vibration amplitude reaching down to 0.3 pm for a detection bandwidth of 1 kHz. The spatial resolution in the scanning plane of the interferometer is better than 1 µm and the detectable vibration frequencies range from 1 MHz to 2.5 GHz. In the thesis, a novel detection method to measure also in-plane vibrations is presented and applied to the analysis of a square-plate MEMS resonator. In the first part of the thesis, operation of novel SAW devices, such as a longitudinal leaky SAW (LLSAW) resonator, a double resonance filter and a piston-mode filter with transverse mode suppression are thoroughly analyzed by combining the interferometric measurement results with numerical simulations and data from electrical measurements. The measurements of the vibration fields in the LLSAW resonator reveal side radiation of Rayleigh waves, which constitutes an acoustic loss mechanism for the resonator. The analysis of the piston-mode filter indicates that one of the parameters for the transverse mode suppression has been underestimated in the filter design. In the second part of the thesis, vibration modes in a square-plate MEMS resonator are analyzed. Comparing the laser-probe measurements with simulations, it can be concluded that the main in-plane vibration mode is companioned by a parasitic out-of-plane mode, that may affect the quality factor of the main mode. The laser-probe measurements enable studying directly the vibrations in SAW and MEMS devices and hence provide new information on the physics and operation of these devices, not obtainable from the electrical measurements or simulations alone. The measurements provide support for the development of new SAW and MEMS components satisfying stringent specifications

Kysely asuntojen radonkorjauksista : STUK-B 274

STUK teki kyselytutkimuksen pientaloasuntojen radonkorjauksista vuonna 2019. Tarkoituksena oli saada tarkempaa tietoa yksittäisistä radonkorjausmenetelmistä. Se oli myös ensimmäinen kerta, kun kysely tehtiin pelkästään sähköisenä. Kutsuja lähetettiin 498 kohteeseen (talouteen) ja vastauksia saatiin 152 ja lopulliseen aineistoon hyväksyttiin 99 kohdetta (20 %). Radonkorjausten tehokkuuksista saatiin samanlaisia tuloksia kuin aikaisemmissakin tutkimuksissa. Radonpitoisuus oli pienentynyt keskimäärin 53 % (mediaani 57 %). Tehokkaimmat menetelmät olivat radonputkiston aktivointi, radonkaivo ja radonimuri. Radonkorjaus asuntoon maksoi tyypillisesti 1000–5000 euroa (mediaani 2300 euroa), kun radonkorjaus oli teetetty kokonaan yrityksellä. Kun radonkorjaus oli tehty kokonaan tai osittain itse, se oli maksanut tyypillisesti 200–1000 euroa (mediaani 500 euroa). Radonkorjaukseen kulunut aika ensimmäisestä, korkean radonpitoisuuden osoittaneesta, mittauksesta vaihteli välillä 3–33 vuotta. Neljännes kyselyyn vastanneista oli tehnyt ensimmäisen mittauksen vuonna 2006 tai sitä ennen. Näissä kohteissa radonkorjauksia on siis tehty melko kauan

Lung cancer incidence attributable to residential radon exposure in Finland

publishedVersionPeer reviewe

The E-cadherin/AmotL2 complex organizes actin filaments required for epithelial hexagonal packing and blastocyst hatching

Epithelial cells connect via cell-cell junctions to form sheets of cells with separate cellular compartments. These cellular connections are essential for the generation of cellular forms and shapes consistent with organ function. Tissue modulation is dependent on the fine-tuning of mechanical forces that are transmitted in part through the actin connection to E-cadherin as well as other components in the adherens junctions. In this report we show that p100 amotL2 forms a complex with E-cadherin that associates with radial actin filaments connecting cells over multiple layers. Genetic inactivation or depletion of amotL2 in epithelial cells in vitro or zebrafish and mouse in vivo, resulted in the loss of contractile actin filaments and perturbed epithelial packing geometry. We further showed that AMOTL2 mRNA and protein was expressed in the trophectoderm of human and mouse blastocysts. Genetic inactivation of amotL2 did not affect cellular differentiation but blocked hatching of the blastocysts from the zona pellucida. These results were mimicked by treatment with the myosin II inhibitor blebbistatin. We propose that the tension generated by the E-cadherin/AmotL2/actin filaments plays a crucial role in developmental processes such as epithelial geometrical packing as well as generation of forces required for blastocyst hatching.Peer reviewe

Radon levels in dwellings and workplaces: a comparison with data from some European countries

Background: According to 2013 European Basic Safety Standards (EU BSS), legal and administrative consequences of having an area declared as radon priority area (RPA) concern workplaces (WP) and public buildings, as well as dwellings (DW). However, RPAs in many cases are defined as higher levels of indoor radon in DW. The reason is that most data are available for DW. So far, indoor radon data for WP (except for schools) and public buildings are scarce. Objective: The objective of this study was to compare indoor radon levels in DW and WP in a given area and to evaluate whether they have different distributions and different average levels. Design: Austria, Finland, Germany, and Italy provided indoor radon data on DW and WP. Data related to WP were aggregated in the same grid, as already done for data on DW, to update the European Indoor Radon Map. Based on 10 km × 10 km grid cells, the same statistics are computed for both datasets. Thus, two structurally equal datasets for each country were generated to be statistically compared. Results and conclusions: Generally, there are numerous indoor radon data on DW than data on WP. Statistical analysis suggests that in all the countries, indoor radon levels – in terms of arithmetic mean (AM) of the natural logarithm-transformed data – in WP and DW are statistically different (P < 0.05), as well as from those referring to schools. The difference in distributions is neither attributable to the effect of geology nor to the effect of different sample sizes. The correlation between aggregated data is positive in the sense that if the mean (over grid cells) radon concentration increases in DW, it increases in WP as well. Compared with DW, in all countries indoor radon levels in WP seem to be statistically different, but the results are not enough to draw final conclusions: on-purpose designed surveys could be a useful tool to better understand this phenomenon

Radon Exposure Concentrations in Finnish Workplaces

The aim of this study was to obtain information on the radon concentrations to which Finnish workers are exposed. Radon measurements were conducted as integrated measurements in 700 workplaces, supplemented by continuous radon measurements in 334 workplaces. The occupational radon concentration was calculated by multiplying the result of the integrated measurements by the seasonal correction factor and the ventilation correction factor (ratio between the working time and the full-time radon concentration obtained from continuous measurement). The annual radon concentration to which workers are exposed was weighted by the actual number of workers in each province. In addition, workers were divided into three main occupational categories (working mainly outdoors, underground, or indoors above ground). Probability distribution of the parameters affecting radon concentration levels were generated to calculate a probabilistic estimate of the number of workers exposed to excessive radon levels. With deterministic methods, the geometric and arithmetic mean radon concentrations in conventional, above-ground workplaces were 41 and 91 Bq m−3, respectively. The estimated geometric and arithmetic mean annual radon concentrations that Finnish workers are exposed to were assessed as 19 and 33 Bq m−3, respectively. The generic ventilation correction factor for workplaces was calculated as 0.87. Assessed with probabilistic methods, there are approximately 34,000 workers in Finland whose exposure to radon exceeds the reference level of 300 Bq m−3. Although radon concentrations are generally low in Finnish workplaces, many workers are exposed to high levels of radon. Radon exposure in the workplace is the most common source of occupational radiation exposure in Finland

Radon uudisrakentamisessa – Otantatutkimus 2016 : Ympäristön säteilyvalvonnan toimintaohjelma

Tutkimuksessa mitattujen asuntojen radonpitoisuuden keskiarvo oli 71 Becquereliä kuutiometrissä ilmaa (Bq/m3) ja mediaani 42 Bq/m3. Keskiarvo oli 25 % ja mediaani 26 % pienempi kuin edellisessä otannassa, vuosina 2006 - 2008 valmistuneissa pientaloissa. Tässä tutkimuksessa radonpitoisuudet olivat korkeiden radonpitoisuuksien maakunnissa 38 % pienempiä kuin seitsemän vuotta sitten tehdyssä tutkimuksessa. Muualla maassa radonpitoisuudet olivat 17 % pienemmät. Uusien asuntojen radonpitoisuuden enimmäisarvo 200 Bq/m3 ylittyi 5,6 % mittauksista. Suurimmat 200 Bq/m3 ylitysosuudet mitattiin Kymenlaaksossa ja Kanta-Hämeessä. Pohjanmaa ja Etelä-Savo olivat ainoita maakuntia, joissa ei esiintynyt kyseisen raja-arvon ylittäviä mittauksia. Arvo 300 Bq/m3 ylittyi 2,1 % kaikista mittauksista ja arvo 400 Bq/m3 1,4 % mittauksista. Radonpitoisuuden mediaani ja keskiarvo sekä ylitysosuudet olivat pienimpiä asunnoissa, joissa oli tuulettuva alapohja. Radonpitoisuudet olivat suurimpia rinne- ja kellaritaloissa. Radontorjuntaa oli tehty eniten Uudellamaalla, Kanta-Hämeessä, Pirkanmaalla, Päijät-Hämeessä, Kymenlaaksossa, Etelä-Karjalassa, Pohjois-Karjalassa ja Keski-Suomessa (> 95 %). Vähiten radontorjuntaa oli tehty Keski- ja Pohjois-Pohjanmaan maakunnissa sekä Ahvenanmaalla (<40 %). Radonputkisto oli asennettu 70 % pientaloista ja korkeiden radonpitoisuuksien maakunnissa 98 % pientaloista. Radontorjuntatoimenpiteiden yleistyminen ja myös mahdollinen tehostuminen ovat alentaneet merkittävästi uusien pientalojen radonpitoisuutta. Rakennusten ilmatiiveyden ja sisäilman radonpitoisuuden välillä havaittiin yhteys niissä asunnoissa, joissa radontorjuntatoimia ei oltu tehty. Ilmatiiveyden kasvaessa, myös mitattu radonpitoisuus nousi. Tämä havainto korostaa ilmatiiviiden talojen radontorjunnan tärkeyttä. Sisäilman radonpitoisuus mitattiin 1332 satunnaisesti valitussa pientaloasunnossa, jotka saivat rakennusluvan aikavälillä marraskuu 2012 – lokakuu 2013. Radonmittaukset tehtiin 1.12.2015 – 15.6.2016. Tutkimukseen hyväksyttyjen mittausten osuus on 48 % alkuperäisestä otannasta ja 87 % tutkimuskutsuun myönteisesti vastanneista. Korkeiden radonpitoisuuksien maakunnissa (Kymenlaakso, Päijät-Häme, Pirkanmaa, Etelä-Karjala ja Kanta-Häme) tutkimukseen ilmoittautui 60 % kutsutuista, kun taas muualla Suomessa vastaava luku oli 54 %. Mittauspurkin palauttaneista 95 % on lopullisessa tutkimusaineistossa. Tämä on 20 % kaikista luvan saaneista ja asuinkäytössä olleista pientalorakennuksista lokakuussa vuonna 2015.1. paino