Antarctic ice shelf melting and its impact on the global sea ice-ocean system

Earth s ice shelves are mainly located in Antarctica. They cover about 44% of the Antarctic coastline and are a salient feature of the continent. Antarctic ice shelf melting (AISM) removes heat from and inputs freshwater into the adjacent Southern Ocean. Although playing an important role in the global climate, AISM is one of the most important components currently absent in the IPCC climate model. In this study, AISM is introduced into a global sea ice-ocean climate model ORCA2-LIM, following the approach of Beckmann and Goosse (2003; BG03) for the thermodynamic interaction between the ice shelf and ocean. This forms the model ORCA2-LIM-ISP (ISP: ice shelf parameterization), in which not only all the major Antarctic ice shelves but also a number of minor ice shelves are included. Using these two models, ORCA2-LIM and ORCA2-LIM-ISP, the impact of addition of AISM and increasing AISM have been investigated. Using the ORCA2-LIM model, numerical experiments are performed to investigate the sensitivity of the polar sea ice cover and the Antarctic Circumpolar Current (ACC) transport through Drake Passage (DP) to the variations of three sea ice parameters, namely the thickness of newly formed ice in leads (h0), the compressive strength of ice (P*), and the turning angle in the oceanic boundary layer beneath sea ice (θ). It is found that the magnitudes of h0 and P* have little impact on the seasonal sea ice extent, but lead to large changes in the seasonal sea ice volume. The variation in turning angle has little impact on the sea ice extent and volume in the Arctic but tends to reduce them in the Antarctica when ignored. The magnitude of P* has the least impact on the DP transport, while the other two parameters have much larger influences. Numerical results from ORCA2-LIM and ORCA2-LIM-ISP are analyzed to investigate how the inclusion of AISM affects the representation of the Southern Ocean hydrography. Comparisons with data from the World Ocean Circulation Experiment (WOCE) show that the addition of AISM significantly improves the simulated hydrography. It not only warms and freshens the originally too cold and too saline bottom water (AABW), but also warms and enriches the salinity of the originally too cold and too fresh warm deep water (WDW). Addition of AISM also improves the simulated stratification. The close agreement between the simulation with AISM and the observations suggests that the applied parameterization is an adequate way to include the effect of AISM in a global sea ice-ocean climate model. We also investigate the models capability to represent the sea ice-ocean system in the North Atlantic Ocean and the Arctic regions. Our study shows both models (with and without AISM) can successfully reproduce the main features of the sea ice-ocean system. However, both tend to overestimate the ice flux through the Nares Strait, produce a lower temperature and salinity in the Hudson Bay, Baffin Bay and Davis Strait, and miss the deep convection in the Labrador Sea. These deficiencies are mainly attributed to the artificial enlargement of the Nares Strait in the model. In this study, the impact of increasing AISM on the global sea ice-ocean system is thoroughly investigated. This provides a first idea regarding changes induced by increasing AISM. It is shown that the impact of increasing AISM is global and most significant in the Southern Ocean. There, increasing AISM tends to freshen the surface water, to warm the intermediate and deep waters, and to freshen and warm the bottom water. In addition, increasing AISM also leads to changes in the mixed layer depths (MLD) in the deep convection sites in the Southern Ocean, deepening in the Antarctic continental shelf while shoaling in the ACC region. Furthermore, increasing AISM influences the current system in the Southern Ocean. It tends to weaken the ACC, and strengthen the Antarctic coastal current (ACoC) as well as the Weddell Gyre and the Ross Gyre. In addition to the ocean system, increasing AISM also has a notable impact on the Antarctic sea ice cover. Due to the cooling of seawater, sea ice concentration and thickness generally become higher. In austral winter, noticeable increases in sea ice concentration mainly take place near the ice edge. In regards with sea ice thickness, large increases are mainly found along the coast of the Weddell Sea, the Bellingshausen and Amundsen Seas, and the Ross Sea. The overall thickening of sea ice leads to a larger volume of sea ice in Antarctica. In the North Atlantic, increasing AISM leads to remarkable changes in temperature, salinity and density. The water generally becomes warmer, more saline and denser. The most significant warming occurs in the subsurface layer. In contrast, the maximum salinity increase is found at the surface. In addition, the MLD becomes larger along the Greenland-Scotland-Iceland ridge. Global teleconnections due to AISM are studied. The AISM signal is transported with the surface current: the additional freshwater from AISM tends to enhance the northward spreading of the surface water. As a result, more warm and saline water is transported from the tropical region to the North Atlantic Ocean, resulting in warming and salt enrichment there. It would take about 30 40 years to establish a systematic noticeable change in temperature, salinity and MLD in the North Atlantic Ocean according to this study. The changes in hydrography due to increasing AISM are compared with observations. Consistency suggests that increasing AISM is highly likely a major contributor to the recent observed changes in the Southern Ocean. In addition, the AISM might contribute to the salinity contrast between the North Atlantic and North Pacific, which is important for the global thermohaline circulation.

Characterisation and processing of amorphous binary mixtures with low glass transition temperature

The number of drug substances in formulation development in the pharmaceutical industry is increasing. Some of these are amorphous drugs and have glass transition below ambient temperature, and thus they are usually difficult to formulate and handle. One reason for this is the reduced viscosity, related to the stickiness of the drug, that makes them complicated to handle in unit operations. Thus, the aim in this thesis was to develop a new processing method for a sticky amorphous model material. Furthermore, model materials were characterised before and after formulation, using several characterisation methods, to understand more precisely the prerequisites for physical stability of amorphous state against crystallisation. The model materials used were monoclinic paracetamol and citric acid anhydrate. Amorphous materials were prepared by melt quenching or by ethanol evaporation methods. The melt blends were found to have slightly higher viscosity than the ethanol evaporated materials. However, melt produced materials crystallised more easily upon consecutive shearing than ethanol evaporated materials. The only material that did not crystallise during shearing was a 50/50 (w/w, %) blend regardless of the preparation method and it was physically stable at least two years in dry conditions. Shearing at varying temperatures was established to measure the physical stability of amorphous materials in processing and storage conditions. The actual physical stability of the blends was better than the pure amorphous materials at ambient temperature. Molecular mobility was not related to the physical stability of the amorphous blends, observed as crystallisation. Molecular mobility of the 50/50 blend derived from a spectral linewidth as a function of temperature using solid state NMR correlated better with the molecular mobility derived from a rheometer than that of differential scanning calorimetry data. Based on the results obtained, the effect of molecular interactions, thermodynamic driving force and miscibility of the blends are discussed as the key factors to stabilise the blends. The stickiness was found to be affected glass transition and viscosity. Ultrasound extrusion and cutting were successfully tested to increase the processability of sticky material. Furthermore, it was found to be possible to process the physically stable 50/50 blend in a supercooled liquid state instead of a glassy state. The method was not found to accelerate the crystallisation. This may open up new possibilities to process amorphous materials that are otherwise impossible to manufacture into solid dosage forms.

Original Pirate Material : Translating Justin Somper's Demons of the Ocean

Tutkielma käsittelee suomentamani Vampiraatit: Kirottujen laiva -nuortenromaanin käännösprosessia. Materiaalina on kustantajalle toimittamani näytekäännös, joka käsittää yhden kokonaisen luvun ja lisäksi kirjan tapahtumiin keskeisesti liittyvän runon. Molemmista tarkastellaan sekä lopullisia, julkaistuja versioita että ensimmäisiä raakaversioita. Julkaistut versiot ovat osa varsinaista tutkielmaa, raakaversiot ja lähtötekstit puolestaan on sisällytetty mukaan liitteinä. Tarkastelunäkökulmani on pääosin deskriptiivinen ja kontrastiivinen. Proosa-analyysi jakautuu kahteen osaan. Ensimmäisessä osassa tutkin tapoja, joilla käännökseni vastustaa ns. lisääntyvän standardisoitumisen lakia (the law of growing standardization), jota Gideon Toury on ehdottanut yleispäteväksi käännöslaiksi. Touryn laki ennustaa, että käännökset ovat useimmiten tyylillisesti alkuteoksiaan latteampia. Esimerkkini kuitenkin osoittavat, että kääntäjän on mahdollista valita ratkaisunsa niin, että latistumiselta vältytään, ainakin silloin, kun lähtöteksti on melko suoraviivaista. Proosa-analyysin jälkimmäinen osa keskittyy käännöksen muokkaamiseen. Vertaan siinä näytekäännös-luvun ensimmäistä versiota julkaistuun versioon ja tutkin muun muassa sitä, missä määrin ensimmäinen versio sisältää lähtökielen interferenssiä, ts. missä määrin englannille tyypilliset rakenteet paistavat siitä läpi. Tarkastelun kohteena ovat myös kohdekieliset kömpelyydet ja niiden poistaminen sekä pienet mutta kokonaisuuden kannalta tärkeät tyylilliset muutokset. Esimerkeistä käy selvästi ilmi kääntämisen prosessimainen luonne. Käännösnäytteeseen sisältyneen runon suomentaminen oli oma erillinen kokonaisuutensa. Tässä osiossa vertailen lähtötekstiä, raakaversiota ja julkaistua käännöstä rinnakkain säkeistö säkeistöltä. Tarkastelussa painottuvat edelleen tekstin muokkaaminen ja hiominen. Analyysien taustaksi esittelen lyhyesti alkuteoksen ja sen kirjoittajan Justin Somperin. Kuvailen myös omaa käännösfilosofiaani ja esittelen kaksi siihen voimakkaasti vaikuttanutta suomentajaa.

Epithelial-mesenchymal transition in oral squamous carcinoma cells

In epithelial-mesenchymal transition (EMT), epithelial cells acquire traits typical for mesenchymal cells, dissociate their cell-cell junctions and gain the ability to migrate. EMT is essential during embryogenesis, but may also mediate cancer progression. Basement membranes are sheets of extracellular matrix that support epithelial cells. They have a major role in maintaining the epithelial phenotype and, in cancer, preventing cell migration, invasion and metastasis. Laminins are the main components of basement membranes and may actively contribute to malignancy. We first evaluated the differences between cell lines obtained from oral squamous cell carcinoma and its recurrence. As the results indicated a change from epithelial to fibroblastoid morphology, E-cadherin to N-cadherin switch, and change in expression of cytokeratins to vimentin intermediate filaments, we concluded that these cells had undergone EMT. We further induced EMT in primary tumour cells to gain knowledge of the effects of transcription factor Snail in this cell model. The E-cadherin repressors responsible for the EMT in these cells were ZEB-1, ZEB-2 and Snail, and ectopic expression of Snail was able to augment the levels of ZEB-1 and ZEB-2. We produced and characterized two monoclonal antibodies that specifically recognized Snail in cell lines and patient samples. By immunohistochemistry, Snail protein was found in mesenchymal tissues during mouse embryonal development, in fibroblastoid cells of healing skin wounds and in fibromatosis and sarcoma specimens. Furthermore, Snail localized to the stroma and borders of tumour cell islands in colon adenocarcinoma, and in laryngeal and cervical squamous cell carcinomas. Immunofluorescence labellings, immunoprecipitations and Northern and Western blots showed that EMT induced a progressive downregulation of laminin-332 and laminin-511 and, on the other hand, an induction of mesenchymal laminin-411. Chromatin immunoprecipitation revealed that Snail could directly bind upstream to the transcription start sites of both laminin α5 and α4 chain genes, thus regulating their expression. The levels of integrin α6β4, a receptor for laminin-332, as well as the hemidesmosomal complex proteins HD1/plectin and BP180 were downregulated in EMT-experienced cells. The expression of Lutheran glycoprotein, a specific receptor for laminin-511, was diminished, whereas the levels of integrins α6β1 and α1β1 and integrin-linked kinase were increased. In quantitative cell adhesion assays, the cells adhered potently to laminin-511 and fibronectin, but only marginally to laminin-411. Western blots and immunoprecipitations indicated that laminin-411 bound to fibronectin and could compromise cell adhesion to fibronectin in a dose-dependent manner. EMT induced a highly migratory and invasive tendency in oral squamous carcinoma cells. Actin-based adhesion and invasion structures, podosomes and invadopodia, were detected in the basal cell membranes of primary tumour and spontaneously transformed cancer cells, respectively. Immunofluorescence labellings showed marked differences in their morphology, as podosomes organized a ring structure with HD1/plectin, αII-spectrin, talin, focal adhesion kinase and pacsin 2 around the core filled with actin, cortactin, vinculin and filamin A. Invadopodia had no division between ring and core and failed to organize the ring proteins, but instead assembled tail-like, narrow actin cables that showed a talin-tensin switch. Time-lapse live-cell imaging indicated that both podosomes and invadopodia were long-lived entities, but the tails of invadopodia vigorously propelled in the cytoplasm and were occasionally released from the cell membrane. Invadopodia could also be externalized outside the cytoplasm, where they still retained the ability to degrade matrix. In 3D confocal imaging combined with in situ gelatin zymography, the podosomes of primary tumour cells were large, cylindrical structures that increased in time, whereas the invadopodia in EMT-driven cells were smaller, but more numerous and degraded the underlying matrix in significantly larger amounts. Fluorescence recovery after photobleaching revealed that the substructures of podosomes were replenished more rapidly with new molecules than those of invadopodia. Overall, our results indicate that EMT has a major effect on the transcription and synthesis of both intra- and extracellular proteins, including laminins and their receptors, and on the structure and dynamics of oral squamous carcinoma cells.

Late Transition Metal and Aluminum Complexes for the Polymerization of Ethene and Acrylates

Polyethene, polyacrylates and polymethyl acrylates are versatile materials that find wide variety of applications in several areas. Therefore, polymerization of ethene, acrylates and methacrylates has achieved a lot attention during past years. Numbers of metal catalysts have been introduced in order to control the polymerization and to produce tailored polymer structures. Herein an overview on the possible polymerization pathways for ethene, acrylates and methacrylates is presented. In this thesis iron(II) and cobalt(II) complexes bearing tri- and tetradentate nitrogen ligands were synthesized and studied in the polymerization of tertbutyl acrylate (tBA) and methyl methacrylate (MMA). Complexes are activated with methylaluminoxane (MAO) before they form active combinations for polymerization reactions. The effect of reaction conditions, i.e. monomer concentration, reaction time, temperature, MAO to metal ratio, on activity and polymer properties were investigated. The described polymerization system enables mild reaction conditions, the possibility to tailor molar mass of the produced polymers and provides good control over the polymerization. Moreover, the polymerization of MMA in the presence of iron(II) complex with tetradentate nitrogen ligands under conditions of atom transfer radical polymerization (ATRP) was studied. Several manganese(II) complexes were studied in the ethene polymerization with combinatorial methods and new active catalysts were found. These complexes were also studied in acrylate and methacrylate polymerizations after MAO activation and converted into the corresponding alkyl (methyl or benzyl) derivatives. Combinatorial methods were introduced to discover aluminum alkyl complexes for the polymerization of acrylates and methacrylates. Various combinations of aluminum alkyls and ligands, including phosphines, salicylaldimines and nitrogen donor ligands, were prepared in situ and utilized to initiate the polymerization of tBA. Phosphine ligands were found to be the most active and the polymerization MMA was studied with these active combinations. In addition, a plausible polymerization mechanism for MMA based on ESI-MS, 1H and 13C NMR is proposed.

Eurasian Neogene large herbivorous mammals and climate

The development and changes in the distribution of herbivorous mammal communities during the Neogene is complex. The Eurasian scale environmental patterns reflect the large scale geographical and climatic patterns. The reorganization of these affect the biome distribution throughout the continent. The distribution of mammal taxa was closely associated with the distribution of biomes. In Eurasia the Neogene development of environments was twofold. The early and middle Miocene that seemed to have been advantageous for mammals was followed by drying of environments during the late Neogene. The mid-latitude drying was the main trend, and it is the combined result of the retreat of Paratethys, the uplift of Tibetan Plateau and changes in the ocean currents and temperatures. The common mammals were "driving" the evolution of mammalian communities. During the late Miocene we see the drying affecting more and more regions, and we see changes in the composition of mammalian communities.

Postglacial climate changes and vegetation responses in northern Europe

Postglacial climate changes and vegetation responses were studied using a combination of biological and physical indicators preserved in lake sediments. Low-frequency trends, high-frequency events and rapid shifts in temperature and moisture balance were probed using pollen-based quantitative temperature reconstructions and oxygen-isotopes from authigenic carbonate and aquatic cellulose, respectively. Pollen and plant macrofossils were employed to shed light on the presence and response rates of plant populations in response to climate changes, particularly focusing on common boreal and temperate tree species. Additional geochemical and isotopic tracers facilitated the interpretation of pollen- and oxygen-isotope data. The results show that the common boreal trees were present in the Baltic region (~55°N) during the Lateglacial, which contrasts with the traditional view of species refuge locations in the south-European peninsulas during the glacial/interglacial cycles. The findings of this work are in agreement with recent paleoecological and genetic evidence suggesting that scattered populations of tree species persisted at higher latitudes, and that these taxa were likely limited to boreal trees. Moreover, the results demonstrate that stepwise changes in plant communities took place in concert with major climate fluctuations of the glacial/interglacial transition. Postglacial climate trends in northern Europe were characterized by rise, maxima and fall in temperatures and related changes in moisture balance. Following the deglaciation of the Northern Hemisphere and the early Holocene reorganization of the ice-ocean-atmosphere system, the long-term temperature trends followed gradually decreasing summer insolation. The early Holocene (~11,700-8000 cal yr BP) was overall cool, moist and oceanic, although the earliest Holocene effective humidity may have been low particularly in the eastern part of northern Europe. The gradual warming trend was interrupted by a cold event ~8200 cal yr BP. The maximum temperatures, ~1.5-3.0°C above modern values, were attained ~8000-4000 cal yr BP. This mid-Holocene peak warmth was coupled with low lake levels, low effective humidity and summertime drought. The late Holocene (~4000 cal yr BP-present) was characterized by gradually decreasing temperatures, higher lake levels and higher effective humidity. Moreover, the gradual trends of the late Holocene were probably superimposed by higher-frequency variability. The spatial variability of the Holocene temperature and moisture balance patterns were tentatively attributed to the differing heat capacities of continents and oceans, changes in atmospheric circulation modes and position of sites and subregions with respect to large water bodies and topographic barriers. The combination of physical and biological proxy archives is a pivotal aspect of this work, because non-climatic factors, such as postglacial migration, disturbances and competitive interactions, can influence reshuffling of vegetation and hence, pollen-based climate reconstructions. The oxygen-isotope records and other physical proxies presented in this work manifest that postglacial climate changes were the main driver of the establishment and expansion of temperate and boreal tree populations, and hence, large-scale and long-term vegetation patterns were in dynamic equilibrium with climate. A notable exception to this pattern may be the postglacial invasion of Norway spruce and the related suppression of mid-Holocene temperate forest. This salient step in north-European vegetation history, the development of the modern boreal ecosystem, cannot be unambiguously explained by current evidence of postglacial climate changes. The results of this work highlight that plant populations, including long-lived trees, may be able to respond strikingly rapidly to changes in climate. Moreover, interannual and seasonal variation and extreme events can exert an important influence on vegetation reshuffling. Importantly, the studies imply that the presence of diffuse refuge populations or local stands among the prevailing vegetation may have provided the means for extraordinarily rapid vegetation responses. Hence, if scattered populations are not provided and tree populations are to migrate long distances, their capacity to keep up with predicted rates of future climate change may be lower than previously thought.

Mining Cell Transition Data

Cell transition data is obtained from a cellular phone that switches its current serving cell tower. The data consists of a sequence of transition events, which are pairs of cell identifiers and transition times. The focus of this thesis is applying data mining methods to such data, developing new algorithms, and extracting knowledge that will be a solid foundation on which to build location-aware applications. In addition to a thorough exploration of the features of the data, the tools and methods developed in this thesis provide solutions to three distinct research problems. First, we develop clustering algorithms that produce a reliable mapping between cell transitions and physical locations observed by users of mobile devices. The main clustering algorithm operates in online fashion, and we consider also a number of offline clustering methods for comparison. Second, we define the concept of significant locations, known as bases, and give an online algorithm for determining them. Finally, we consider the task of predicting the movement of the user, based on historical data. We develop a prediction algorithm that considers paths of movement in their entirety, instead of just the most recent movement history. All of the presented methods are evaluated with a significant body of real cell transition data, collected from about one hundred different individuals. The algorithms developed in this thesis are designed to be implemented on a mobile device, and require no extra hardware sensors or network infrastructure. By not relying on external services and keeping the user information as much as possible on the user s own personal device, we avoid privacy issues and let the users control the disclosure of their location information.