Photolithographic fabrication method of computer-generated holographic interferograms

We consider the fabrication of high-quality interferogram-type diffractive optical elements with conventional photolithographic techniques and compare the results with those achievable with electron-beam lithography. The fringes associated with the phase transfer function of the binary phase holographic interferogram are approximated with rectangles, which can be realized at submicron accuracy using a pattern generator and step-and-repeat camera. The effects of the rectangle quantization are analyzed both numerically and experimentally with the aid of diffraction patterns produced by simple focusing elements. Both resolution and diffraction efficiency of the best holograms approach their theoretical values

Interfacial compatibility of polymer-based structures in electronics

Interfacial compatibility of dissimilar materials was investigated to achieve a better understanding of interfacial adhesion in metal/polymer/metal systems. Surface modifications of polymers were applied to improve the adhesion. The modified surfaces were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements accompanied by surface free energy evaluations. The pull-off test was employed to assess the interfacial adhesion strength. Further, to determine the controlling adhesion mechanism, the fracture surfaces exposed in the pull-off test were examined by microscopy. To achieve modification of certain bulk properties of one of the evaluated polymers (SU8 epoxy resin), new star-shaped oligomers were synthesised and reactively blended with it. Oligomers were characterised by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC). Films of the blends were spin coated on a silicon wafer for characterisation of the refractive index and a novel non-destructive method was developed to measure selected thermal properties of the films. The information concerning interfacial compatibility obtained in this work is of great practical as well as theoretical importance.reviewe

Cellular Digital Post-Distortion : Signal Processing Methods and RF Measurements

In this paper, we study the feasibility of digital post-distortion (DPoD) based mitigation of transmitter nonlinear distortion in cellular networks. With specific emphasis on downlink, we describe a computationally efficient one-shot method to estimate and mitigate the cascaded multipath channel and transmitter nonlinear distortion effects at terminal receiver, building on demodulation reference symbols (DMRSs). We also describe a DMRS boosting approach to match the envelope characteristics of the DMRS and the actual data-bearing multicarrier symbols such that accurate mitigation is feasible. We provide RF measurement results with a state-of-the-art 28 GHz active antenna array and 256-QAM data modulation, demonstrating larger performance enhancements in received signal error vector magnitude (EVM) compared to existing computationally expensive iterative methods.Peer reviewe

Spatially varying peatland initiation, Holocene development, carbon accumulation patterns and radiative forcing within a subarctic fen

High latitude peatlands act as globally important carbon (C) sinks and are in constant interaction with the atmosphere. Their C storage formed during the Holocene. In the course of time, the aggregate effect of the C fluxes on radiative forcing (RF) typically changes from warming to cooling, but the timing of this shift varies among different peatlands. Here we investigated Holocene peatland development, including vegetation history, vertical peat growth and the lateral expansion of a patterned subarctic fen in northern Finland by means of multiple sampling points. We modelled the Holocene RF by combining knowledge on past vegetation communities based on plant macrofossil stratigraphies and present in situ C flux measurements. The peatland initiated at ca. 9500 calibrated years Before Present (cal yr BP), and its lateral expansion was greatest between ca. 9000 and 7000 cal yr BP. After the early expansion, vertical peat growth proceeded very differently in different parts of the peatland, regulated by internal and external factors. The pronounced surface microtopography, with high strings and wet (larks, started to form only after ca. 1000 cal yr BP. C accumulation within the peatland recorded a high degree of spatial variability throughout its history, including the recent past. We applied two flux scenarios with different interpretation of the initial peatland development phases to estimate the RF induced by C fluxes of the fen. After ca. 4000 cal yr BP, at the latest, the peatland RF has been negative (cooling), mainly driven by C uptake and biomass production, while methane emissions had a lesser role in the total RF. Interestingly, these scenarios suggest that the greatest cooling effect took place around ca. 1000 cal yr BP, after which the surface microtopography established. The study demonstrated that despite the high spatial heterogeneity and idiosyncratic behaviour of the peatland, the RF of the studied fen followed the general development pattern of more southern peatlands. Holocene climate variations and warm phases did not seem to induce any distinctive and consistent peatland-scale patterns in C accumulation, whereas our data suggests that the changes in vegetation related to autogenic succession were reflected in the C accumulation patterns and RF more clearly. (C) 2020 Elsevier Ltd. All rights reserved.Peer reviewe

Parallel Delta-Sigma Modulator-Based Digital Predistortion of Wideband RF Power Amplifiers

In this article, we propose a new robust and highly efficient digital predistortion (DPD) concept for the linearization of wideband RF power amplifiers (PAs). The proposed approach is based on the combination of a parallelized delta-sigma modulator (DSM) and a forward model of the PA. This concept applies multi-rate techniques on a DSM that incorporates the forward PA model in its feedback loop to perform the required signal predistortion. Such a technique eliminates the need of reverse modeling and its associated problems. The multi-rate approach relaxes enormously the clock speed requirement of the DPD, which allows handling high signal bandwidths at feasible sampling rates. Moreover, enhanced performance can be achieved without the need of increasing the order of the modulator which reduces the sensitivity of the system to gain variations and phase distortions caused by the nonlinear PA characteristics. Three time-interleaved parallel DPD (P-DPD) variants are described and introduced, all of them have been shown to offer increased accuracy, and consequently better linearization performance compared to the DSM-based DPD state-of-the-art. The proposed architectures are tested and assessed using extensive real-world RF measurements at the 3.6 GHz band utilizing wideband 100 MHz 5G New Radio (NR) transmit waveforms, evidencing excellent transmit signal quality.publishedVersionPeer reviewe

Kiintoaineen eroosio ja sedimentaatio virtavesissä - luonnollisesta prosessista virtavesien ongelmaksi

Valuma-alueiden eroosio ja vedessä kulkeutuvan kiintoaineen sedimentaatio ovat luonnollisia prosesseja virtavesissä. Ne ylläpitävät virtavesien elinympäristöjen monimuotoisuutta. Ihmistoiminta, erityisesti maankäyttö, on kuitenkin merkittävästi lisännyt eroosiota ja hienon kiintoaineksen määrää virtavesissä, millä on lukuisia haitallisia vaikutuksia virtavesien ekosysteemeihin. Tässä kirjallisuuskatsauksessa kuvataan virtavesien luontaisen sekä ihmistoiminnan muuttaman kiintoaineen eroosion ja sedimentaation merkitystä virtavesissä. Katsauksessa käsitellään liiallisen kiintoainekuormituksen ja sedimentaation vaikutuksia virtavesien perustuotantoon ja vesikasvillisuuteen, pohjaeläimiin, kaloihin sekä mikrobeihin ja hajotusprosesseihin. Lisäksi käsitellään kiintoainekuormituksen ja sedimentaation arvioinnin ja vesienhoidon kannalta keskeisiä seuranta-, vesiensuojelu- ja kunnostusmenetelmiä sekä tutkimustarpeita

Rare protein-altering variants in ANGPTL7 lower intraocular pressure and protect against glaucoma

Protein-altering variants that are protective against human disease provide in vivo validation of therapeutic targets. Here we use genotyping data from UK Biobank (n = 337,151 unrelated White British individuals) and FinnGen (n = 176,899) to conduct a search for protein-altering variants conferring lower intraocular pressure (IOP) and protection against glaucoma. Through rare protein-altering variant association analysis, we find a missense variant in ANGPTL7 in UK Biobank (rs28991009, p.Gln175His, MAF = 0.8%, genotyped in 82,253 individuals with measured IOP and an independent set of 4,238 glaucoma patients and 250,660 controls) that significantly lowers IOP (beta = -0.53 and -0.67 mmHg for heterozygotes, -3.40 and -2.37 mmHg for homozygotes, P = 5.96 x 10(-9) and 1.07 x 10(-13) for corneal compensated and Goldman-correlated IOP, respectively) and is associated with 34% reduced risk of glaucoma (P = 0.0062). In FinnGen, we identify an ANGPTL7 missense variant at a greater than 50-fold increased frequency in Finland compared with other populations (rs147660927, p.Arg220Cys, MAF Finland = 4.3%), which was genotyped in 6,537 glaucoma patients and 170,362 controls and is associated with a 29% lower glaucoma risk (P = 1.9 x 10(-12) for all glaucoma types and also protection against its subtypes including exfoliation, primary open-angle, and primary angle-closure). We further find three rarer variants in UK Biobank, including a protein-truncating variant, which confer a strong composite lowering of IOP (P = 0.0012 and 0.24 for Goldman-correlated and corneal compensated IOP, respectively), suggesting the protective mechanism likely resides in the loss of interaction or function. Our results support inhibition or down-regulation of ANGPTL7 as a therapeutic strategy for glaucoma. Author summary Glaucoma is a common eye disease that damages the optic nerve. Using intraocular pressure, which is a known modifiable risk factor and predictive measure for glaucoma, genome-wide association studies have identified dozens of genetic variants likely affecting disease risk. However, the identification of potential therapeutic targets from those discoveries has been challenging because the functional consequences and the causal variants of the suggested common variant associations are typically unclear. Here, we present a strategy to scan for rare protein-altering variants, which provides direct insights into the functional consequence and the therapeutic effects, using more than 514,000 individuals with European ancestries in two population cohorts in the UK and Finland. We discover an allelic series of multiple rare ANGPTL7 missense and nonsense variants in UK Biobank that lower intraocular pressure and reduces the risk of glaucoma. We further identify an ANGPTL7 missense variant in FinnGen cohort with more than 50-fold enrichment in the Finnish population that provides protection against glaucoma and its subtypes. Our results highlight the benefits of multi-cohort analysis for the discovery of rare protein-altering variants in common diseases and indicate ANGPTL7 as a therapeutic target for glaucoma.Peer reviewe

Muovien haitalliset ympäristö- ja terveysvaikutukset

Muoveja päätyy ympäristöön useista lähteistä. Etenkin kevyet muovit voivat kulkeutua kauas alkuperäisiltä päästölähteiltään. Muovit voivat kuljettaa mukanaan mm. vieraslajeja, taudinaiheuttajia sekä haitallisia yhdisteitä. Muoveja pääsee ympäristöön kaikista muovin elinkaaren vaiheista, mutta yksi merkittävimmistä päästölähteistä on elinkaaren loppupäässä muodostuvat roskat. Muovit ovat ympäristössä erittäin pysyviä. Suurikokoiset muovit voivat pilkkoutua edelleen pienemmiksi muodostaen mikromuoveja, jotka pienen kokonsa vuoksi kulkeutuvat helpommin eliöihin. Ympäristöön päädyttyään muovit voivat aiheuttaa monenlaisia vaikutuksia. Vesiympäristössä suurikokoisten muovien tunnetuimmat haitat ovat eliöiden takertuminen niihin sekä muovikappaleiden syömisestä aiheutuvat ongelmat. Maaekosysteemien osalta tietoa muovien vaikutuksista on varsin vähän. Nykytiedon valossa näyttäisi siltä, että vaikutukset ovat samansuuntaisia vesiympäristön kanssa. Mikromuovien on todettu puolestaan vaikuttavan haitallisesti useisiin eri ravintoverkon tasojen eliöihin. Vesiympäristössä monien eri lajien on havaittu altistuvan mikromuovihiukkasille. Eliöihin kulkeutuneet mikromuovit voivat aiheuttaa niissä hyvin monen tyyppisiä haittavaikutuksia. Maaympäristössä maaperäeläimet voivat myös toimia mikromuovien reittinä maanpäälliseen ravintoverkkoon. Ihmiset altistuvat mikromuoveille päivittäin ravinnon, sisä- ja ulkoilman sekä ihon kautta, mutta altistumisen määrää ja sen mahdollisia vaikutuksia terveyteen ei tarkkaan tunneta. Koe-eläimillä ja solumalleilla tehdyissä tutkimuksissa on saatu viitteitä haitallisista vaikutuksista, mutta näissä tutkimuksissa käytetyt suuret annosmäärät ja tasalaatuiset muovilajit eivät vastaa ihmisten tavanomaista altistumista. Vaikka näyttö terveysvaikutuksista on vähäistä, kansainväliset tiedejärjestöt ovat arvioineet, että mikromuovialtistus on tällä hetkellä niin pientä, että siitä ei aiheudu merkittävää riskiä ihmisten terveydelle. Tilanne voi kuitenkin muuttua ympäristön mikromuovisaastemäärän kasvaessa. Lisää tietoa tarvitaan erityisesti nanokokoisten muovihiukkasten käyttäytymisestä elimistössä, pienten lasten altistumisesta, mahdollisista suolistovaikutuksista sekä pitkäaikaisen elimistöön kertymisen seurauksista. Jätteen synnyn ehkäisy ja kiertotalouden optimointi on tärkeää muovien aiheuttamien ympäristövaikutusten pitämiseksi mahdollisimman pieninä. Vuonna 2018 laadittu Muovitiekartta on esittänyt useita toimenpide-ehdotuksia muovien käytön vähentämiseksi, korvaamiseksi sekä kierrätyksen tehostamiseksi. Ekologisesti kestävä ja turvallisuusnäkökulmat huomioiva tuotesuunnittelu on osaltaan avainasemassa muovien ilmasto- ja ympäristöpäästöjen vähentämisessä. Vaikka muoveja ja niiden vaikutuksiin kohdistuvaa sääntelyä on viime vuosina lisätty, on puutteita edelleen havaittavissa. Ensisijaisena hallintakeinona voidaan kuitenkin nähdä muovien ympäristöpäästöjen estäminen. Eräs keskeinen ongelma kuitenkin on, että suoria ohjauskeinoja sekundääristen mikromuovien syntymisen ehkäisemiseksi ei ole. Muovin ollessa edelleen keskeisessä roolissa useissa yhteiskunnan toiminnoissa, tarvitaan jatkossa edelleen monen tasoisia hallintakeinoja muovien aiheuttamien ympäristö- ja terveysvaikutusten vähentämiseksi.Adverse environmental and health effects of plastics Plastic enters the environment from various emission sources. In particular, light plastics may be transported long distances from their original emission sources. Plastics may also carry alien species, pathogens, and hazardous substances. Plastics are released into the environment from all stages of their life cycle, but one of the most significant sources is plastic waste generated at the end of the life cycle. In the environment plastics are extremely persistent. Large plastics items can be further broken down into smaller pieces which, due to their small size, are more easily transported into organisms. Once released into the environment, plastics may have a wide range of various impacts. In an aquatic environment, the most common disadvantages of large plastics are the tangling of organisms in them, and the problems caused by organisms eating plastic pieces. There is a lack of information on the impacts of plastics on terrestrial ecosystems. However, according to the information available the impacts on the terrestrial environment seem to be quite parallel to the aquatic environment. Microplastics have been found to have adverse impacts on several organisms at different trophic levels. In an aquatic environment various species have been found to be exposed to microplastic particles. Microplastics introduced into organisms can cause many types of unwanted side effects. In a terrestrial environment, soil animals can also act as a pathway for microplastics into the terrestrial food web. Humans are exposed to microplastics on a daily basis through food, indoor and outdoor air, and the skin, but the extent of the exposure and its potential effects on health are not well known. Laboratory studies in animals and cell models have shown evidence of adverse effects, but the high doses and uniform plastic types used in these studies do not correspond to normal human exposure. Even though the evidence for health effects is limited, international scientific community has estimated that microplastic exposure is currently so low that it does not pose a significant risk to human health. However, the situation may change as the amount of microplastic pollution in the environment keep increasing. More information is required, especially on the behavior of nanosized plastic particles in the human body, the exposure of young children to plastics, the possible intestinal effects and the consequences of long-term accumulation. Waste prevention and optimizing the circular economy are important ways to minimize the environmental impact of plastics. The Plastic Roadmap launched in 2018 has set several proposals for measures to reduce and replace plastic use and to increase the efficiency of recycling. Ecologically sustainable product design that also takes into account safety perspectives plays a key role in reducing climate and environmental emissions from plastics. Although the legislation and regulative measures of plastics and their impacts has increased in recent years, shortcomings still remain. The prevention of plastic emissions to the environment can be seen as a primary control measure. One key problem, however, is that there are no direct control methods to prevent secondary plastics emissions. As plastic keeps playing a key role in many activities in society, multi-level management measures are still required to reduce the environmental and health impacts of plastics