6 resultados para Negative Binomial model

em Helda - Digital Repository of University of Helsinki


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Tämän tutkielman tarkoituksena on määrittää kesämökkikäynnin virkistysarvo. Aihetta ei ole aikaisemmin tutkittu, vaikka kesämökkeily on merkittävä osa suomalaista elämää. Kesämökkikäynnin virkistysarvo tarkoittaa hyötyä, jonka yksilö saa kesämökillä virkistäytymisestä. Virkistäytyminen kesämökillä pitää sisällään kaiken kesämökillä ja sen ympäristössä tapahtuvan harrastamisen ja rentoutumisen. Koska ympäristö on tärkeässä osassa mökillä virkistäytymisessä, tässä tutkielmassa on lisäksi tarkoitus tutkia, kuinka mökkiympäristön ominaisuudet vaikuttavat virkistysarvoon. Tarkasteltavina ympäristön ominaisuuksina ovat virkistäytymisen estävät leväkukinnot ja mökin rannattomuus. Koska mökkeily toisaalta myös kuormittaa ympäristöä, tutkielmassa tutkitaan myös, kuinka sähköistys, ympäristöä kuormittava kesämökin ominaisuus, vaikuttaa virkistysarvoon. Virkistysarvo on markkinaton hyöty, joten sen määrittämiseen on käytettävä jotain markkinattomien hyödykkeiden arvottamismenetelmää. Tässä työssä arvottaminen tapahtuu matkakustannusmenetelmällä, jota käytetään yleisesti ympäristön tarjoamien virkistyspalveluiden taloudelliseen arvottamiseen. Kesämökkikäyntien kysyntää kuvaava matkakustannusmallin ekonometrinen mallintaminen suoritetaan negatiivisella binomimallilla. Tutkielman tulosten mukaan noin neljän päivän pituinen käynti sähköistetyllä kesämökillä, jossa on ranta eivätkä levät häiritse virkistäytymistä, tuottaa 167-205 euron suuruisen virkistyshyödyn. Virkistäytymisen estävät leväkukinnot laskevat arvoa 40 prosentilla ja mökin rannattomuus 45 prosentilla. Käynti sähköistetyllä mökillä tuottaa 3-5 prosenttia korkeamman virkistyshyödyn kuin käynti sähköistämättömällä mökillä. Suomessa kesän aikana tehtävien mökkikäyntien yhteenlaskettu virkistyshyöty on 430-530 miljoonaa, jos mökillä on ranta, jossa levistä ei ole haittaa. Häiritsevät leväkukinnot laskevat yhteenlaskettua virkistyshyötyä 30 miljoonalla ja rannattomuus 10-20 miljoonalla. Sähköistys nostaa yhteenlaskettua virkistyshyötyä 20-30 miljoonalla eurolla.

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Sea-surface wind observations of previous generation scatterometers have been successfully assimilated into Numerical Weather Prediction (NWP) models. Impact studies conducted with these assimilation implementations have shown a distinct improvement to model analysis and forecast accuracies. The Advanced Scatterometer (ASCAT), flown on Metop-A, offers an improved sea-surface wind accuracy and better data coverage when compared to the previous generation scatterometers. Five individual case studies are carried out. The effect of including ASCAT data into High Resolution Limited Area Model (HIRLAM) assimilation system (4D-Var) is tested to be neutral-positive for situations with general flow direction from the Atlantic Ocean. For northerly flow regimes the effect is negative. This is later discussed to be caused by problems involving modeling northern flows, and also due to the lack of a suitable verification method. Suggestions and an example of an improved verification method is presented later on. A closer examination of a polar low evolution is also shown. It is found that the ASCAT assimilation scheme improves forecast of the initial evolution of the polar low, but the model advects the strong low pressure centre too fast eastward. Finally, the flaws of the implementation are found small and implementing the ASCAT assimilation scheme into the operational HIRLAM suite is feasible, but longer time period validation is still required.

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In Finland, there is a desperate need for flexible, reliable and functional multi-e-learning settings for pupils aged 11-13. Southern Finland has several ongoing e-learning projects, but none that develop a multiple setting, with learning and teaching occurring between more than two schools. In 2006, internet connections were not broadband and data transfer was mainly audio data. Connections and technical problems occurred, which were an obstacle to multi-e-learning. Internet connections today enable web-based learning in major parts of
Lapland and by 2015, broadband will reach even the remotest villages up north. Therefore, it is important to research the possibilities of multi-e-learning and to build collaborative, learner-centred, versatile network models for primary school-aged pupils. The resulting model will facilitate distance learning to extend education to rural, sparsely populated areas, and it will give a model of using mobile devices in language portfolios. This will promote regional equality and prevent exclusion. Working with portfolios provides the opportunity to develop mobility from a pedagogical point of view. It is important to study the pros and cons of mobile devices in producing artefacts on portfolios in e-learning and language learning settings.
The current study represents a design-based research approach. The design research approach includes two important aspects concerning the current research: ‘a teacher as researcher’ aspect, which means there is the possibility to be strongly involved in developing processes and an obstacle-aspect, which means that problems while developing, are seen as a
promoter in evolving the designed model, as apposed to negative results.

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In Finland, there is a desperate need for flexible, reliable and functional multi-e-learning settings for pupils aged 11-13. Southern Finland has several ongoing e-learning projects, but none that develop a multiple setting, with learning and teaching occurring between more than two schools. In 2006, internet connections were not broadband and data transfer was mainly audio data. Connections and technical problems occurred, which were an obstacle to multi-e-learning. Internet connections today enable web-based learning in major parts of Lapland and by 2015, broadband will reach even the remotest villages up north. Therefore, it is important to research the possibilities of multi-e-learning and to build collaborative, learner-centred, versatile network models for primary school-aged pupils. The resulting model will facilitate distance learning to extend education to rural, sparsely populated areas, and it will give a model of using mobile devices in language portfolios. This will promote regional equality and prevent exclusion. Working with portfolios provides the opportunity to develop mobility from a pedagogical point of view. It is important to study the pros and cons of mobile devices in producing artefacts on portfolios in e-learning and language learning settings. The current study represents a design-based research approach. The design research approach includes two important aspects concerning the current research: ‘a teacher as researcher’ aspect, which means there is the possibility to be strongly involved in developing processes and an obstacle-aspect, which means that problems while developing, are seen as a promoter in evolving the designed model, as apposed to negative results.

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A vast literature documents negative skewness and excess kurtosis in stock return distributions on several markets. We approach the issue of negative skewness from a different angle than in previous studies by suggesting a model, which we denote the “negative news threshold” hypothesis, that builds on asymmetrically distributed information and symmetric market responses. Our empirical tests reveal that returns for days when non-scheduled news are disclosed are the source of negative skewness in stock returns. This finding lends solid support to our model and suggests that negative skewness in stock returns is induced by asymmetries in the news disclosure policies of firm management.

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Coagulase-negative staphylococci (CNS) are the most common bacteria isolated in bovine subclinical mastitis in many countries, and also a frequent cause of clinical mastitis. The most common species isolated are Staphylococcus (S) chromogenes, S. simulans, S. epidermidis, and S. xylosus. One half of the intramammary infections (IMI) caused by CNS persist in the udder. The pathogenesis of IMI caused by CNS is poorly understood. This dissertation focuses on host response in experimental intramammary infection induced by S. chromogenes, S. epidermidis and S. simulans. Model for a mild experimental CNS infection was developed with S. chromogenes (study I). All cows were infected and most developed subclinical mastitis. In study II the innate immune response to S. epidermidis and S. simulans IMI was compared in eight cows using a crossover design. A larger dose of bacteria was used to induce clinical mastitis. All cows became infected and showed mild to moderate clinical signs of mastitis. S. simulans caused a slightly stronger innate immune response than S. epidermidis, with significantly higher concentrations of the interleukins IL-1beta and IL-8 in the milk. The spontaneous elimination rate of the 16 IMIs was 31%, with no difference between species. No significant differences were recorded between infections eliminated spontaneously or remaining persistent, although the response was stronger in IMIs eliminated spontaneously, except the concentration of TNF-α, which remained elevated in persistent infections. Lactoferrin (Lf) is a component of the humoral defence of the host and is present at low concentrations in the milk. The concentration of Lf in milk is high during the dry period, in colostrum, and in mastitic milk. The effect of an inherent, high concentration of Lf in the milk on experimental IMI induced with S. chromogenes was studied in transgenic cows that expressed recombinant human Lf in their milk. Human Lf did not prevent S. chromogenes IMI, but the host response was milder in transgenic cows than in normal cows, and the former eliminated infection faster. Biofilm production has been suggested to promote persistence of IMI. Phenotypic biofilm formation and slime producing ability of CNS isolates from bovine mastitis was investigated in vitro. One-third of mastitis isolates produced biofilm. Slime production was less frequent for isolates of the most common mastitis causing species S. chromogenes and S. simulans compared with S. epidermidis. No association was found between the phenotypic ability to form biofilm and the persistence of IMI or severity of mastitis. Slime production was associated with persistent infections, but only 8% of isolates produced slime.