Lumen latvusinterseption ajallinen vaihtelu metsätyypeittäin Suomessa

Tiivistelmä. Lumen latvusinterseptiolla tarkoitetaan kasvillisuuden, erityisesti puuston kykyä siepata satavaa lunta latvustoonsa. Puuston lumen latvusinterseptiota on tutkittu paljon, mutta tutkimuksia niiden trendeistä on vain vähän. Tämän tutkielman päätarkoituksena on selvittää, onko lumen latvusinterseption määrässä havaittavissa muutoksia viimeisen 70 vuoden aikana Suomessa. Lisäksi tutkielmassa tarkastellaan mahdollisia eroja lumen latvusinterseption määrissä metsätyyppien (kuusi-, mänty- ja lehtipuuvaltainen metsä) välillä sekä kolmen ympäristömuuttujan (ilman lämpötila, kokonaissadanta ja lumen määrä) suhteen. Tutkielman aineisto on kerätty 23:sta lumilinjasta eri puolilta Suomea vapaaehtoisten mittaajien toimesta ja se on saatu käyttöön Suomen ympäristökeskukselta. Tämän tutkielman analyysit tehtiin R-ohjelmistolla. Lumen latvusinterseption muutosten tarkastelussa käytetään Mann-Kendallin trenditestiä. Metsätyyppien välisessä lumen latvusinterseption erojen tarkastelussa on käytetty Kruskal-Wallisin ja Dunnin post-hoc testejä. Lisäksi ympäristömuuttujien vaikutusta lumen latvusinterseptioon tarkasteltiin yksinkertaisen lineaarisen regressioanalyysin avulla. Etelä-Suomessa havaittiin lumen latvusinterseption määrien pääosin kasvaneen. Vastaavasti Pohjois-Suomessa lumen latvusinterseption määrissä ei havaittu tapahtuneen muutoksia. Metsätyypeistä kuusivaltaisessa metsässä lumen latvusinterseptio oli kaikkein suurinta ja lehtipuuvaltaisessa metsässä pienintä. Ympäristömuuttujista lämpötila näytti vaikuttavan lumen latvusinterseption määrään kaikkein eniten. Sen vaikutus kuitenkin heikkenee kylmemmille ilmastoalueille siirryttäessä. Kokonaissadanta ja lumen määrä näyttivät vaikuttavan lumen latvusinterseption määrään pelkästään Pohjois-Suomessa. Lämpötilamuuttujan huomattiin mahdollisesti jopa kontrolloivan muiden ympäristömuuttujien merkitystä lumen latvusinterseption suhteen

Reconfigurable quadruple quantum dots in a silicon nanowire transistor

We present a novel reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consist of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired with improved silicon fabrication techniques, makes the corner state quantum dot approach a promising candidate for a scalable quantum information architecture

Usefulness of high resolution coastal models for operational oil spill forecast: the "Full City" accident

Oil spill modeling is considered to be an important part of a decision support system (DeSS) for oil spill combatment and is useful for remedial action in case of accidents, as well as for designing the environmental monitoring system that is frequently set up after major accidents. Many accidents take place in coastal areas, implying that low resolution basin scale ocean models are of limited use for predicting the trajectories of an oil spill. In this study, we target the oil spill in connection with the "Full City" accident on the Norwegian south coast and compare operational simulations from three different oil spill models for the area. The result of the analysis is that all models do a satisfactory job. The "standard" operational model for the area is shown to have severe flaws, but by applying ocean forcing data of higher resolution (1.5 km resolution), the model system shows results that compare well with observations. The study also shows that an ensemble of results from the three different models is useful when predicting/analyzing oil spill in coastal areas

Measurement of isotope shift in Eu II

The isotope shift between singly-charged ^Eu and ^Eu in the 4f^7(^8S^o)6s^9S_4-4f^7(^8S^o)6p_1/2>(J=4) transition at 4129 A has been measured using fast ion beam-laser technique. This Eu line has attracted interest in connection with efforts of obtaining a cosmochronometer based on observed Th/Eu abundance ratios. Knowledge of the isotope shift is of importance in order to check that contaminations from line blends do not contribute to the line intensity of Eu II. The measured value of the isotope shift -0.1527(2) cm-1 (= -4578 MHz) is consistent with the old spectroscopic value of Krebs and Winkler -0.1503(25) cm-1 using a Fabry Perot interferometer, while the accuracy is improved substantially.Comment: 12 pages, in press for Physica Scripta, in swete

Summer eczema in exported Icelandic horses: influence of environmental and genetic factors

A cross sectional study was designed to estimate the prevalence of summer eczema (a chronic, recurrent seasonal dermatitis) in exported Icelandic horses and the influence of environmental and genetic factors on the development of the disease. Among 330 horses, which had been exported to Germany, Denmark and Sweden, 114 (34.5%) were found to have clinical signs of summer eczema. The prevalence was highest 2 years after export and the exposure to the biting midges Culicoides spp., was found to be the main risk factor for developing the disease. Genetic influence on the sensitivity for the disease was not established. It was concluded that exported Icelandic horses are predisposed for summer dermatitis and the fact that they are not introduced to the antigens of the biting midges early in live, due to it's absence in Iceland, is likely to explain the high prevalence of the disease after export

Characteristics of equine summer eczema with emphasis on differences between Finnhorses and Icelandic horses in a 11-year study

Summer eczema, allergic dermatitis of the horse, was studied on 275 affected horses in Finland in 1997–2007. Features of the horses, clinical signs of the disease and owners' opinions of aggravating factors were recorded. Differences, especially, between two of the native Scandinavian horse breeds, the Finnhorse and the Icelandic horse, were evaluated. The study was based on clinical examination and information from the owners. Of the horses, 50% were Finnhorses, 26% Icelandic horses and 24% consisted of different breeds of ponies and other horses. Of the Finnhorses, 76% had summer eczema by the age of 5 years, but in the Icelandic horses born in Finland the average age at onset was 7 years. The vast majority of the horses, 75%, had moderate clinical signs, while 16% showed severe and 9% mild. The severity of clinical signs did not depend on the duration of the disease nor was it related to the age at onset. The only linkage to severity was the breed of the horse or import from Iceland; New Forest ponies and imported Icelandic horses showed severe clinical signs significantly more often than Finnhorses. Of the owners, 38% regarded insects as the only aggravating factor, 24% mentioned several simultaneous factors, including grass fodder and sunlight, while 22% could not specify any. In Finland, a typical horse breed suffering from summer eczema is the Finnhorse and the characteristics of the disease are mainly uniform with the other breeds affected. Equine summer eczema seems to be aggravated by various combinations of environmental factors

Mass flow and variability in screw feeding of biomass powders – relations to particle and bulk properties

Biomass powders are often cohesive, have low bulk density and poor material flow characteristics which causes interruptions and variations in feeding systems. In this study, a range of biomasses - commercial charcoal, torrefied Norway spruce stem wood, non-treated Norway spruce stem wood, and reed canary grass - was milled (screen size: 1 mm) using two different milling methods; cutting mill and hammer mill, to form eight types of biomass powders. Powders were analyzed for loose density, Hausner ratio, compression ratio, angle of repose and for size and shape distributions. Size and shape were determined by mechanical sieving and optical particle size and shape analysis. Additionally, yield loci and wall yield loci were determined through standard bulk solids testing methods. Screw feeding properties of the eight biomass powders were determined by feeding the materials in a twin screw feeder - at constant rpm and at a constant feeding rate of 1 kg/h. Correlation analysis and principal component loadings were used to describe relations between material properties and feeding characteristics. When materials were fed at a constant rpm, feeding variability was closely correlated to the powders’ angle of repose (long time step) and Hausner and compression ratio (short time step)

Pollen productivity estimates of key European plant taxa for quantitative reconstruction of past vegetation: a review

International audienceInformation on the spatial distribution of past vegetation on local, regional and global scales is increasingly used within climate modelling, nature conservancy and archaeology. It is possible to obtain such information from fossil pollen records in lakes and bogs using the landscape reconstruction algorithm (LRA) and its two models, REVEALS and LOVE. These models assume that reliable pollen productivity estimates (PPEs) are available for the plant taxa involved in the quantitative reconstruc -tions of past vegetation, and that PPEs are constant through time. This paper presents and discusses the PPEs for 15 tree and 18 herb taxa obtained in nine study areas of Europe. Observed differences in PPEs between regions may be explained by methodological issues and environmental variables, of which climate and related factors such as reproduction strategies and growth forms appear to be the most important. An evaluation of the PPEs at hand so far suggests that they can be used in modelling applications and quantitative reconstructions of pastvegetation, provided that consideration of past environmental variability within the region is used to inform selection of PPEs, and bearing in mind that PPEs might have changed through time as a response to climate change. Application of a range of possible PPEs will allow a better evaluation of the results

Europe's lost forests: a pollen-based synthesis for the last 11,000 years

8000 years ago, prior to Neolithic agriculture, Europe was mostly a wooded continent. Since then, its forest cover has been progressively fragmented, so that today it covers less than half of Europe’s land area, in many cases having been cleared to make way for fields and pasture-land. Establishing the origin of Europe’s current, more open land-cover mosaic requires a long-term perspective, for which pollen analysis offers a key tool. In this study we utilise and compare three numerical approaches to transforming pollen data into past forest cover, drawing on >1000 14C-dated site records. All reconstructions highlight the different histories of the mixed temperate and the northern boreal forests, with the former declining progressively since ~6000 years ago, linked to forest clearance for agriculture in later prehistory (especially in northwest Europe) and early historic times (e.g. in north central Europe). In contrast, extensive human impact on the needle-leaf forests of northern Europe only becomes detectable in the last two millennia and has left a larger area of forest in place. Forest loss has been a dominant feature of Europe’s landscape ecology in the second half of the current interglacial, with consequences for carbon cycling, ecosystem functioning and biodiversity