20 resultados para Underwater observations

em Helda - Digital Repository of University of Helsinki


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Pro gradu-työni aihe on ruokaterminologiaa käsittelevät ranskan puhekielen ja Pariisin slangin lainasanat sekä kirjailija Frédéric Dardin alias San-Antonion (1921-2000) luomat, ruokatermistöön kuuluvat uudissanat ja -sanonnat kahdessa San-Antonio-romaanissa C'est mort et ça ne sait pas sekä Le fil à couper le beurre. Näissä ns. kioskikirjallisuutta edustavissa rikosromaaneissa seikkailee puheenparttaan ruoka-alan termeillä höystävä, "erikoistehtäviä" hoitava komisario ja naistenmies, San-Antonio. Ranskankielisessä arjen kielenkäytössä vilisee ruokaan liittyviä sanoja ja sanontoja muissakin kuin varsinaisissa ruuanvalmistus- ja ateriointiyhteyksissä. Halusin tarkastella, millaisena tämä yleisesti havaitsemani ilmiö todentuu Frédéric Dardin kahdessa romaanissa, jotka olen valinnut aineistokseni. Frédéric Dard käyttää romaaneissaan varsin omaperäistä kieltä: sekä puhekieltä että Pariisin slangia. Korpukseni koostuu romaaneista poimimistani ruoka-alan termistöä sisältävistä esimerkeistä, joita valmiiseen työhön tuli 228 kappaletta. Jaoin kaikki korpuksesta löytämäni ruokatermit kahteen luokkaan sen mukaan, oliko kirjailija lainannut käyttämänsä sanan tai ilmauksen puhekielestä tai Pariisin slangista (lainatermit), vai oliko hän luonut termin tai ilmauksen itse (neologismit). Määrittelin termin tai ilmauksen neologismiksi, jos se ei esiintynyt joko laisinkaan tai ainakaan kirjailijan tarkoittamassa merkityksessä seuraavissa sanakirjoissa: Le Dictionnaire du français argotique, populaire et familier; Le Dictionnaire de l'argot moderne; Le Dictionnaire du français non conventionnel; Le Dictionnaire de l'argot; Le Dictionnaire du français argotique et populaire; L'argot chez les vrais de vrai ja Trésor de la langue française. Varsinainen tutkimus perustuu sanojen ja ilmausten merkitysten selvittämiseen ja analysointiin. Lainatermien analyysillä tarkoitan lainatermien merkitysten selvitystä em. sanakirjojen avulla. Neologismit analysoin tarkemmin käyttäen em. sanakirjoja sekä tukeutuen gastronomisten ja erityisesti kielitieteellisten lähdeteosteni tarjoamiin rakenteellisiin ja semanttisiin muodostustapoihin ja tekemällä niistä tarvittavat yhteenvedot oikean merkityksen selvittämiseksi. Käsittelin aineiston kaikki ruokatermit. Niiden valtavan lukumäärän vuoksi analysoitavien esimerkkien määrää piti rajoittaa niin, että valmiiseen työhön jäi jokaisesta termistä enintään kaksi esimerkkiä kummastakin korpuksen kirjasta eli yhteensä 228 esimerkkiä. Muut esimerkit luetteloin työn lopusta löytyvään liitteeseen. Neologismianalyysissä selvisi, että Frédéric Dard suosi erityisesti semanttisia muodostustapoja eli olemassa olevan merkityksen muuttamista metaforien ja kielikuvien avulla. Dardin rikas terminologia ja hänen humoristiset oivalluksensa ovat osaltaan rikastuttaneet ranskan puhekieltä.Työssäni totean, että Pariisin slangia ja puhekieltä on totuttu pitämään sosiaalisesti sopimattomana, marginaalisten ryhmien kielenä, vaikka sen ilmauksia saattaa nykyisin kuulla jopa akateemikkojen käyttävän, ja ilmauksia on siirtynyt slangi- ja puhekielestä yleiskieleen. Toivon työni edistävän kiinnostusta kielitaidon parantamiseen San-Antonion tyyliin tutustumisen avulla sekä herättävän mielenkiintoa ranskan kielen vivahteikkuuteen ja monimuotoisuuteen muullakin kuin yleiskielen tasolla. Kielessä ei mielestäni voi olla sellaisia osa-alueita, joiden opiskelu ja osaaminen olisi tarpeetonta.

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A wide range of models used in agriculture, ecology, carbon cycling, climate and other related studies require information on the amount of leaf material present in a given environment to correctly represent radiation, heat, momentum, water, and various gas exchanges with the overlying atmosphere or the underlying soil. Leaf area index (LAI) thus often features as a critical land surface variable in parameterisations of global and regional climate models, e.g., radiation uptake, precipitation interception, energy conversion, gas exchange and momentum, as all areas are substantially determined by the vegetation surface. Optical wavelengths of remote sensing are the common electromagnetic regions used for LAI estimations and generally for vegetation studies. The main purpose of this dissertation was to enhance the determination of LAI using close-range remote sensing (hemispherical photography), airborne remote sensing (high resolution colour and colour infrared imagery), and satellite remote sensing (high resolution SPOT 5 HRG imagery) optical observations. The commonly used light extinction models are applied at all levels of optical observations. For the sake of comparative analysis, LAI was further determined using statistical relationships between spectral vegetation index (SVI) and ground based LAI. The study areas of this dissertation focus on two regions, one located in Taita Hills, South-East Kenya characterised by tropical cloud forest and exotic plantations, and the other in Gatineau Park, Southern Quebec, Canada dominated by temperate hardwood forest. The sampling procedure of sky map of gap fraction and size from hemispherical photographs was proven to be one of the most crucial steps in the accurate determination of LAI. LAI and clumping index estimates were significantly affected by the variation of the size of sky segments for given zenith angle ranges. On sloping ground, gap fraction and size distributions present strong upslope/downslope asymmetry of foliage elements, and thus the correction and the sensitivity analysis for both LAI and clumping index computations were demonstrated. Several SVIs can be used for LAI mapping using empirical regression analysis provided that the sensitivities of SVIs at varying ranges of LAI are large enough. Large scale LAI inversion algorithms were demonstrated and were proven to be a considerably efficient alternative approach for LAI mapping. LAI can be estimated nonparametrically from the information contained solely in the remotely sensed dataset given that the upper-end (saturated SVI) value is accurately determined. However, further study is still required to devise a methodology as well as instrumentation to retrieve on-ground green leaf area index . Subsequently, the large scale LAI inversion algorithms presented in this work can be precisely validated. Finally, based on literature review and this dissertation, potential future research prospects and directions were recommended.

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When organisms compete for mates and fertilisations, the process of sexual selection drives the evolution of traits that increase reproductive success. The traits targeted by selection, and the extent to which they change, are constrained by the local environment. Sexual selection due to female mate choice can be undermined by alternative reproductive tactics (ARTs), which refers to discontinuous variation in traits or behaviours used in reproduction. As human activities are rapidly changing our planet, this raises the question how ARTs will be affected. Fish show a bewildering diversity of ARTs, which make them good model organisms to answer these questions. One example of human-induced environmental change, which is affecting aquatic ecosystems around the world, is eutrophication, the over-enrichment of water bodies with nutrients. One of its effects is decreased underwater visibility due to increases in both turbidity and vegetation density. The aims of this thesis were to investigate the effects increased turbidity and vegetation density have on an ART in sticklebacks, a fish common to marine and fresh water bodies of the Northern hemisphere. I furthermore investigated how this affected sexual selection for male size, a trait commonly under selection. I used a combination of behavioural observations in microcosms, where I manipulated underwater visibility, with collection of genetic material to reconstruct parentage of broods, and thus identify sneak fertilisations. The results show that turbidity might have weak negative effects on the frequency of sneaking behaviour, although this behaviour was rather infrequent in these experiments, which complicates firm conclusions. In dense vegetation the number of sneak fertilisations decreased slightly, as fewer nesting males sneaked, while the number of non-nesting males sneaking remained constant. The paternity analyses revealed that a significantly smaller fraction of eggs was sneak fertilised under dense vegetation. Furthermore, amongst the nesting males that sneaked, the amount of eggs sneak fertilised correlated positively with courtship success. A reduction in sneaking by these males under dense vegetation equalised the distribution of fertilisation success, in turn contributing to a decrease in the opportunity for selection. Under dense vegetation significantly more males built nests, which has also been observed in previous field studies. In a separate experiment we addressed if such changes in the proportion of nesters and non-nesters, without changes in visibility, affected the incidence of sneak fertilisation. My results show this was not the case, likely because sneaking is an opportunistic tactic shown by both nesters and non-nesters. Non-nesters did sneak proportionately more when there were many of them, which could be due to changes in the cost-benefit ratio of sneaking. As nesters can only attack one intruder at a time, the costs and risks per sneaker will decrease as the number of sneakers increases. The defensive behaviours shown by the nesters before spawning shifted to a more aggressive form of nest defence. This could be because less aggressive behaviours lose their effectiveness when the number of intruders increases. It could also indicate that the risks associated with aggressive behaviours decrease when there are fewer fellow nesters, as other studies indicate nesters are competitive and aggressive individuals. Under turbid conditions I did not detect changes in the opportunity for selection, based on fertilisation success, nor was male size under significant selection under clear or turbid conditions. More thorough analyses under densely vegetated conditions across the nesting, courtship and fertilisation stages revealed a decrease in the opportunity for selection across all stages. A reduction in sneaking by nesters contributed to this. During the nesting stage, but not during later stages, body size was under significant directional selection under sparse, but not dense vegetation. This illustrates the importance of considering all selection stages to get a complete picture of how environmental changes affect sexual selection. Leaving out certain stages or subgroups can result in incomplete or misleading results.

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The intervertebral disc is composed of concentrically arranged components: annulus fibrosus, the transition zone, and central nucleus pulposus. The major disc cell type differs in various parts of the intervertebral disc. In annulus fibrosus a spindle shaped fibroblast-like cell mainly dominates, whereas in central nucleus pulposus the more rounded chondrocyte-like disc cell is the major cell type. At birth the intervertebral disc is well vascularized, but during childhood and adolescence blood vessels become smaller and less numerous. The adult intervertebral disc is avascular and is nourished via the cartilage endplates. On the other hand, degenerated and prolapsed intervertebral discs are again vascularized, and show many changes compared to normal discs, including: nerve ingrowth, change in collagen turnover, and change in water content. Furthermore, the prolapsed intervertebral disc tissue has a tendency to decrease in size over time. Growth factors are polypeptides which regulate cell growth, extracellular matrix protease activity, and vascularization. Oncoproteins c-Fos and c-Jun heterodimerize, forming the AP-1 transcription factor which is expressed in activated cells. In this thesis the differences of growth factor expression in normal intervertebral disc, the degenerated intervertebral disc and herniated intervertebral disc were analyzed. Growth factors of particular interest were basic fibroblast growth factor (bFGF or FGF-2), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and transforming growth factor beta (TGFβ). Cell activation was visualized by the expression of the AP-1 transcription promoters c-Fos and c-Jun. The expression was shown with either mono- or polyclonal antibodies by indirect avidin-biotin-peroxidase immunohistochemical staining method. The normal control material was collected from a tissue bank of five organ donors. The degenerated disc material was from twelve patients operated on for painful degenerative disc disease, and herniated disc tissue material was obtained from 115 patients operated on for sciatica. Normal control discs showed only TGFβ immunopositivity. All other factors studied were immunonegative in the control material. Prolapsed disc material was immunopositive for all factors studied, and this positivity was located either in the disc cells or in blood vessels. Furthermore, neovascularization was noted. Disc cell immunoreaction was shown in chondrocyte-like disc cells or in fibroblast-like disc cells, the former being expressed especially in conglomerates (clusters of disc cells). TGFβ receptor induction was prominent in prolapsed intervertebral disc tissue. In degenerated disc material, the expression of growth factors was analyzed in greater detail in various parts of the disc: nucleus pulposus, anterior annulus fibrosus and posterior annulus fibrosus. PDGF did not show any immunoreactivity, whereas all other studied growth factors were localized either in chondrocyte-like disc cells, often forming clusters, in fibroblast-like disc cells, or in small capillaries. Many of the studied degenerated discs showed tears in the posterior region of annulus fibrosus, but expression of immunopositive growth factors was detected throughout the entire disc. Furthermore, there was a difference in immunopositive cell types for different growth factors. The main conclusion of the thesis, supported by all substudies, is the occurrence of growth factors in disc cells. They may be actively participating in a network regulating disc cell growth, proliferation, extracellular matrix turnover, and neovascularization. Chondrocyte-like disc cells, in particular, expressed growth factors and oncoproteins, highlighting the importance of this cell type in the basic pathophysiologic events involved in disc degeneration and disc rearrangement. The thesis proposes a hypothesis for cellular remodelling in intervertebral disc tissue. In summary, the model presents an activation pattern of different growth factors at different intervertebral disc stages, mechanisms leading to neovascularization of the intervertebral disc in pathological conditions, and alteration of disc cell shape, especially in annulus fibrosus. Chondrocyte-like disc cells become more numerous, and these cells are capable of forming clusters, which appear to be regionally active within the disc. The alteration of the phenotype of disc cells expressing growth factors from fibroblast-like disc cells to chondrocyte-like cells in annulus fibrosus, and the numerous expression of growth factor expressing disc cells in nucleus pulposus, may be a key element both during pathological degeneration of the intervertebral disc, and during the healing process after trauma.

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In this thesis, the solar wind-magnetosphere-ionosphere coupling is studied observationally, with the main focus on the ionospheric currents in the auroral region. The thesis consists of five research articles and an introductory part that summarises the most important results reached in the articles and places them in a wider context within the field of space physics. Ionospheric measurements are provided by the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network, by the low-orbit CHAllenging Minisatellite Payload (CHAMP) satellite, by the European Incoherent SCATter (EISCAT) radar, and by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite. Magnetospheric observations, on the other hand, are acquired from the four spacecraft of the Cluster mission, and solar wind observations from the Advanced Composition Explorer (ACE) and Wind spacecraft. Within the framework of this study, a new method for determining the ionospheric currents from low-orbit satellite-based magnetic field data is developed. In contrast to previous techniques, all three current density components can be determined on a matching spatial scale, and the validity of the necessary one-dimensionality approximation, and thus, the quality of the results, can be estimated directly from the data. The new method is applied to derive an empirical model for estimating the Hall-to-Pedersen conductance ratio from ground-based magnetic field data, and to investigate the statistical dependence of the large-scale ionospheric currents on solar wind and geomagnetic parameters. Equations describing the amount of field-aligned current in the auroral region, as well as the location of the auroral electrojets, as a function of these parameters are derived. Moreover, the mesoscale (10-1000 km) ionospheric equivalent currents related to two magnetotail plasma sheet phenomena, bursty bulk flows and flux ropes, are studied. Based on the analysis of 22 events, the typical equivalent current pattern related to bursty bulk flows is established. For the flux ropes, on the other hand, only two conjugate events are found. As the equivalent current patterns during these two events are not similar, it is suggested that the ionospheric signatures of a flux rope depend on the orientation and the length of the structure, but analysis of additional events is required to determine the possible ionospheric connection of flux ropes.

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It is widely accepted that the global climate is heating up due to human activities, such as burning of fossil fuels. Therefore we find ourselves forced to make decisions on what measures, if any, need to be taken to decrease our warming effect on the planet before any irrevocable damage occurs. Research is being conducted in a variety of fields to better understand all relevant processes governing Earth s climate, and to assess the relative roles of anthropogenic and biogenic emissions into the atmosphere. One of the least well quantified problems is the impact of small aerosol particles (both of anthropogenic and biogenic origin) on climate, through reflecting solar radiation and their ability to act as condensation nuclei for cloud droplets. In this thesis, the compounds driving the biogenic formation of new particles in the atmosphere have been examined through detailed measurements. As directly measuring the composition of these newly formed particles is extremely difficult, the approach was to indirectly study their different characteristics by measuring the hygroscopicity (water uptake) and volatility (evaporation) of particles between 10 and 50 nm. To study the first steps of the formation process in the sub-3 nm range, the nucleation of gaseous precursors to small clusters, the chemical composition of ambient naturally charged ions were measured. The ion measurements were performed with a newly developed mass spectrometer, which was first characterized in the laboratory before being deployed at a boreal forest measurement site. It was also successfully compared to similar, low-resolution instruments. The ambient measurements showed that sulfuric acid clusters dominate the negative ion spectrum during new particle formation events. Sulfuric acid/ammonia clusters were detected in ambient air for the first time in this work. Even though sulfuric acid is believed to be the most important gas phase precursor driving the initial cluster formation, measurements of the hygroscopicity and volatility of growing 10-50 nm particles in Hyytiälä showed an increasing role of organic vapors of a variety of oxidation levels. This work has provided additional insights into the compounds participating both in the initial formation and subsequent growth of atmospheric new aerosol particles. It will hopefully prove an important step in understanding atmospheric gas-to-particle conversion, which, by influencing cloud properties, can have important climate impacts. All available knowledge needs to be constantly updated, summarized, and brought to the attention of our decision-makers. Only by increasing our understanding of all the relevant processes can we build reliable models to predict the long-term effects of decisions made today.

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Atmospheric aerosol particles have a significant impact on air quality, human health and global climate. The climatic effects of secondary aerosol are currently among the largest uncertainties limiting the scientific understanding of future and past climate changes. To better estimate the climatic importance of secondary aerosol particles, detailed information on atmospheric particle formation mechanisms and the vapours forming the aerosol is required. In this thesis we studied these issues by applying novel instrumentation in a boreal forest to obtain direct information on the very first steps of atmospheric nucleation and particle growth. Additionally, we used detailed laboratory experiments and process modelling to determine condensational growth properties, such as saturation vapour pressures, of dicarboxylic acids, which are organic acids often found in atmospheric samples. Based on our studies, we came to four main conclusions: 1) In the boreal forest region, both sulphurous compounds and organics are needed for secondary particle formation, the previous contributing mainly to particle formation and latter to growth; 2) A persistent pool of molecular clusters, both neutral and charged, is present and participates in atmospheric nucleation processes in boreal forests; 3) Neutral particle formation seems to dominate over ion-mediated mechanisms, at least in the boreal forest boundary layer; 4) The subcooled liquid phase saturation vapour pressures of C3-C9 dicarboxylic acids are of the order of 1e-5 1e-3 Pa at atmospheric temperatures, indicating that a mixed pre-existing particulate phase is required for their condensation in atmospheric conditions. The work presented in this thesis gives tools to better quantify the aerosol source provided by secondary aerosol formation. The results are particularly useful when estimating, for instance, anthropogenic versus biogenic influences and the fractions of secondary aerosol formation explained by neutral or ion-mediated nucleation mechanisms, at least in environments where the average particle formation rates are of the order of some tens of particles per cubic centimeter or lower. However, as the factors driving secondary particle formation are likely to vary depending on the environment, measurements on atmospheric nucleation and particle growth are needed from around the world to be able to better describe the secondary particle formation, and assess its climatic effects on a global scale.

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This work is focused on the effects of energetic particle precipitation of solar or magnetospheric origin on the polar middle atmosphere. The energetic charged particles have access to the atmosphere in the polar areas, where they are guided by the Earth's magnetic field. The particles penetrate down to 20-100 km altitudes (stratosphere and mesosphere) ionising the ambient air. This ionisation leads to production of odd nitrogen (NOx) and odd hydrogen species, which take part in catalytic ozone destruction. NOx has a very long chemical lifetime during polar night conditions. Therefore NOx produced at high altitudes during polar night can be transported to lower stratospheric altitudes. Particular emphasis in this work is in the use of both space and ground based observations: ozone and NO2 measurements from the GOMOS instrument on board the European Space Agency's Envisat-satellite are used together with subionospheric VLF radio wave observations from ground stations. Combining the two observation techniques enabled detection of NOx enhancements throughout the middle atmosphere, including tracking the descent of NOx enhancements of high altitude origin down to the stratosphere. GOMOS observations of the large Solar Proton Events of October-November 2003 showed the progression of the SPE initiated NOx enhancements through the polar winter. In the upper stratosphere, nighttime NO2 increased by an order of magnitude, and the effect was observed to last for several weeks after the SPEs. Ozone decreases up to 60 % from the pre-SPE values were observed in the upper stratosphere nearly a month after the events. Over several weeks the GOMOS observations showed the gradual descent of the NOx enhancements to lower altitudes. Measurements from years 2002-2006 were used to study polar winter NOx increases and their connection to energetic particle precipitation. NOx enhancements were found to occur in a good correlation with both increased high-energy particle precipitation and increased geomagnetic activity. The average wintertime polar NOx was found to have a nearly linear relationship with the average wintertime geomagnetic activity. The results from this thesis work show how important energetic particle precipitation from outside the atmosphere is as a source of NOx in the middle atmosphere, and thus its importance to the chemical balance of the atmosphere.