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  • Siikamäki, Heli (Helsingin yliopisto, 2015)
    Study I analyzed Finnish travellers health problems abroad during 2010 2012. Information was drawn from a database kept by an assistance organization of insurance companies covering 95% of Finnish cases requiring aid abroad. The study included 50 710 cases. These data were compared to numbers of Finnish travellers from the Official Statistics of Finland to calculate incidences of illness and injury at various destinations. The most common diagnostic categories proved to be infections (60%) and injuries (14%); the most frequent diagnoses were acute gastroenteritis (23%) and respiratory infections (21%). Incidence was high in Africa, southern Europe plus the eastern Mediterranean, and Asia. Pre-travel counselling appears advisable also for visitors to southern Europe. Means for preventing gastrointestinal and respiratory infections are needed. Study II explored the final diagnoses of returning travellers with fever. This retrospective investigation comprised 462 febrile adults returning from malaria-endemic areas admitted to the Helsinki University Central Hospital emergency room during 2005 2009. The most common diagnostic categories were acute diarrhoeal disease (27%), systemic febrile illness (15%), and respiratory illness (15%). One traveller in four had a potentially life-threatening illness; septicemia proved as common as malaria (5% vs. 4%); one in ten had more than one diagnosis. The results suggest that the diagnostic protocol in tertiary hospital should in addition to malaria smears comprise blood cultures, influenza rapid test, and HIV test. Study III analyzed surveillance data on malaria cases reported to the National Infectious Disease Register 1995 2008 totalling 484 cases, and related them to travel statistics and antimalarial drug sales. The number of visits to malaria-endemic areas increased, whereas malaria cases did not, and a decreasing trend appeared in antimalarial drug sales. Infections were mostly acquired in Africa (76%). The most common species was Plasmodium falciparum (61%). Of all cases, 42% proved of foreign origin; in 89%, the infection was contracted in the region of birth, implying that immigrants visiting friends and relatives constitute a risk group with a particular need for pre-travel advice. Study IV analyzed in detail the background information on malaria cases diagnosed in Finland 2003 2011. The data included 265 cases, 54% of whom were born in malaria-endemic countries, and 86% currently lived in non-endemic regions. Of those born in non-endemic regions, 81% had received pre-travel advice, but only 20% of those born in endemic ones. Among travellers infected with P. falciparum, 4% reported regular use of appropriate chemoprophylaxis, yet individual rechecking by interview revealed that none had been fully compliant. These data suggest that, if taken conscientiously, mefloquine, atovaquone/proguanil, and doxycycline are effective as chemoprophylaxis against P. falciparum malaria.
  • Österman, Janina (Helsingin yliopisto, 2015)
    Växter och djur är beroende av kväve för att kunna syntetisera nödvändiga biologiska föreningar så som aminosyror och nukleotider. Även om det finns ett överflöd av kvävgas i atmosfären, kan växter inte använda sig av kvävgasen som sådan, utan den måste först omvandlas (fixeras) till ammoniak. Kvävefixerande bakterier har en naturlig förmåga att fixera kvävgas till fördel för växterna. Det här fenomenet kallas biologisk kvävefixering. Bakterierna kan antingen vara frilevande eller leva i symbios med baljväxter. I motsats till industriell kvävefixering, en energikrävande process som är beroende av hög temperatur och högt tryck för att binda kväve i kvävegödsel, utnyttjar biologisk kvävefixering enbart solenergi för samma reaktion. Biologisk kvävefixering begränsas å andra sidan av krav på kompatibilitet mellan värdväxter och kvävefixerande mikroorganismer, effektiviteten av kvävefixeringen samt mikroorganismernas förmåga att överleva under krävande förhållanden. Den rådande efterfrågan på mer hållbara sätt att producera mat för jordens befolkning gör biologisk kvävefixering ett attraktivt alternativ. För att kunna ersätta använding av industriellt kvävegödsel krävs ändå att existerande biologiska kvävefixeringssystem optimeras och att nya högproduktiva system utvecklas. Detta å sin sida förutsätter förbättrad kunskap om de krav som både växter och mikroorganismer ställer för att en lyckad, effektiv kvävefixering ska vara möjlig. I denna avhandling användes som modellsystem växt bakterie paret Galega (getärt) och Neorhizobium galegae, som ingår kvävefixerande symbios med varandra, för att studera särdrag som är kännetecknande för en lyckad symbiotisk kvävefixering. Studier av den genetiska diversiteten inom värdväxten visade att genetiska drag skiljer de två arterna G. orientalis och G. officinalis åt, både då hela genomet beaktas och på ett plan av specifika symbiosrelaterade gener. Genomsekvensering av tio stammar av N. galegae tillhandahöll ett användbart dataset för att studera genetiska drag som dels skiljer N. galegae från närbesläktade kvävefixerande bakterier (rhizobier), dels delar in stammar av N. galegae i två symbiovarer (d.v.s. varianter av bakterien som uttrycker sig olika på de två olika värdväxtarterna av Galega). Dessa studier resulterade i ny information om gener som kan vara involverade i att bestämma värdväxtspecificiteten och effektivitetsgraden för kvävefixeringen. Dessutom identifierades genetiskt innehåll som ger ny information om bakteriens ekologi. Av största vikt var att genomsekvenseringen ledde till identifiering av genen noeT, som modifierar den så kallade Nod faktorn (en signalmolekyl som behövs för initiering av en fungerande symbios) hos N. galegae. Även om det visade sig att noeT inte spelar den avgörande rollen som möjliggör symbios med arter av Galega som tidigare antogs, så utgör dessa resultat en viktig grund för kommande studier av mekanismerna som bidrar till den selektivitet (värdväxtspecificitet) som präglar den kvävefixerande symbiosen mellan Galega och N. galegae.
  • Yaghi, Nader (Helsingin yliopisto, 2015)
    In terms of chemistry, phosphate (PV) and arsenate (AsV) are similar, but their biochemical roles are completely different. Phosphorus (P) is an important nutrient for all forms of life but when entering to watercourses it increases the eutrophication risk. Arsenic (As) is a metalloid, the inorganic species of which are toxic, with AsIII classified as a first group carcinogen. This work was undertaken to investigate the potential of Light Expanded Clay Aggregates (LECAs) to act as sorbents to remove P and As species from the aqueous phase. Detailed studies were undertaken to determine if the efficiency of LECAs can be improved by coating them with aluminum (Al) or iron (Fe) oxide. The ability of various LECA materials to remove P from water was compared at different pH values, and the reversibility and kinetics of the reactions were investigated. The results revealed that the oxide-coated LECAs were superior to LECAs as P sorbents. Furthermore, Al-LECAs was superior to Fe-LECAs, which is redox-sensitive and therefore may lose its sorption properties in temporarily prevailing anoxic conditions, e.g., in constructed wetlands (CWs) used for wastewater purification. Studies of the reaction kinetics, impact of the degree of P saturation (DPS) and P desorption revealed that the oxide-coated materials retained P more strongly than LECAs. The experiments with As were designed to simulate the conditions in groundwater where As exists as AsV or AsIII, depending on the redox potential. The optimal pH for the sorption of both As species, the effect of oxidizing agents on the sorption of AsIII and the effect of competing phosphate anions on As sorption were investigated in systematic studies, which revealed that the oxide coatings decisively increased the sorption of both As species. For AsV at a pH of 4, Al-LECAs appeared to be a better sorbent than Fe-LECAs. However, Fe-LECAs were superior to Al-LECAs at a pH of 6. The sorption of AsIII increased with elevated pH. At a pH of 9, sorption was greater onto Al-LECAs than Fe-LECAs. However, the opposite trend was obtained at a pH of 10. The oxidation of AsIII to AsV enhanced sorption by LECAs. Moreover, the oxidation-reduction reaction created new sorption sites for AsV on the manganese dioxide (MnO2) surface. The competition with P for sorption sites relatively diminished the retention of As onto LECAs compared to the oxide-coated LECAs. In the Al-LECAs, the P-induced decrease in the AsV sorption was larger than that in the Fe-LECAs. The competition between P and AsIII lowered the sorption by oxide-coated LECAs most markedly in acidic media. Thus, LECAs seem to be the best option for removing AsIII and AsV from groundwater with high P. The sorption properties of LECA materials were assessed by means of sorption isotherms describing the sorption as a function of the sorbate concentration in the solution after equilibration The actual P sorption capacity was assessed as the P retained at a P concentration of 20 μg L−1 in the equilibrium solution (X20), which is close to the upper limit (25 µg L-1) allowed in surface water to avoid eutrophication. The corresponding actual sorption capacity for the As species was determined at an equilibrium concentration of 10 μg As L−1 (X10), which is the highest allowable level in drinking water.
  • Mehtälä, Juha (Helsingin yliopisto, 2015)
    Continuous-time Markov processes with a finite state space can be used to model countless real world phenomena. Therefore, researchers often encounter the problem of estimating the transition rates that govern the dynamics of such processes. Ideally, the estimation of transition rates would be based on observed transition times between the states in the model, i.e., on continuous-time observation of the process. However, in many practical applications only the current status of the process can be observed on a pre-defined set of time points (discrete-time observations). The estimation of transition rates is considerably more challenging when based on discrete-time data as compared to continuous observation. The difficulty arises from missing data due to the unknown evolution of the process between the actual observation times. To be able to estimate the rates reliably, additional constraints on how they vary in time will usually be necessary. A real world application considered in this thesis involves the asymptomatic carriage state (colonisation) with the bacterium \textit{Streptococcus pneumoniae} (the pneumococcus). The pneumococcus has over 90 strains and for understanding the dynamics of the pneumococcus among humans it is important to understand within-host competition between these strains. Research questions regarding competition in this thesis are: does colonisation by one serotype protect from acquisition of other serotypes and is clearance affected by concurrent colonisation by other serotypes? A question regarding the implication of competition to pneumococcal dynamics after vaccination is also of interest. In addition, vaccine protection may be heterogeneous across individuals, leading to a question about how well such vaccine protection can be estimated from discrete-time data. When only discrete-time observations are available, the decision when to measure the current status of the process is particularly important. With measurements that are temporally apart from each other, information about the state of the process at one point does not give information about the state at the other points. When measurements are very close to each other, knowing the state at one point bears information about the state at other, temporally close points. This thesis addresses the estimation of transition rates based on repeated observations of the current status of an underlying continuous-time Markov process. Applications to actual data concern the process of pneumococcal colonisation. Optimal study designs are considered for improved future studies of similar type, applications including but not limited to pneumococcal colonisation studies.
  • Loman, Tina (Helsingin yliopisto, 2015)
    Health behaviours are important to prevention and public health. Health behaviours include usually food habits, physical activity, drinking, smoking and sleeping. Improving health behaviours help reduce risks for several major chronic diseases and mortality. Food habits and physical activity play a key role in reducing weight gain and related disease risk. Health behaviours are socially patterned and they vary between socioeconomic groups, and contribute to inequalities in health. In order to reduce socioeconomic differences in health, novel evidence is needed of changes in socioeconomic differences of health behaviours as well as reasons behind the socioeconomic differences. The main aim of this study was to examine socioeconomic differences in food habits, physical activity and weight gain, and their changes over time among middle-aged female and male public sector employees. Specific aims were to examine first changes in occupational class differences in food habits and second in physical inactivity and activity during a follow-up of 5-7 years, considering the effects of covariates. The third specific aim was to examine the association between weight gain and multiple socioeconomic indicators. This study is part of the Helsinki Health Study (HHS). The baseline data were collected by questionnaire surveys in 2000, 2001 and 2002 (n=8 960, response rate 67%). Mail surveys were sent to employees of the City of Helsinki aged 40-60 years. The follow-up survey data were collected in 2007 among the baseline respondents (n=7 332, response rate 83%). For data analysis general linear models, logistic regression analysis and the relative index of inequality were used. In many food habits, there was a hierarchical order according to occupational class, i.e. those in higher occupational classes used more often the studied food item than those in lower classes. In some food habits, there was a reverse hierarchical order and in some food habits there were no socioeconomic differences. Occupational class differences largely remained stable over the follow-up in the food habits. At baseline, there were no occupational class differences in leisure-time physical activity, but over the follow-up physical activity increased among women with the highest occupational class and decreased among men with the lowest occupational class, suggesting the emergence of occupational class differences at follow-up. The covariates (age, marital status, body mass index physical and mental health functioning, employment status) did not substantially affect the observed occupational class differences in leisure-time physical activity at follow-up. Among women and men, socioeconomic differences were observed in at least 5 kg weight gain, and current economic difficulties showed the strongest association with weight gain. Socioeconomic differences largely remained stable over the 5-7 year follow-up in food habits, whereas in leisure-time physical activity differences emerged. There were clear differences in weight gain by economic difficulties. Thus, there is a continuous need for reducing socioeconomic inequalities in the studied health behaviours. Healthy behaviours should be promoted in particular among those in lower occupational classes and those with economic difficulties.
  • Tuomela, Annika (Helsingin yliopisto, 2015)
    Low oral bioavailability and general delivery problems related to poorly water soluble drugs are major challenges in pharmaceutical formulation development. Nanocrystal technologies have been introduced as advantageous formulation approaches for these molecules. Nanocrystals, with greater surface to volume ratio, can effectively increase both the dissolution rate and saturation solubility of active ingredients. The aim of this thesis was to obtain detailed knowledge about the dissolution characteristics of drug nanocrystals, and to develop feasible nanocrystal applications for ocular and oral drug delivery purposes. Hence, develop-ability issues from the analytical difficulties of the drug dissolution behavior to the scale-ability of the nanocrystals were covered. A new approach in dissolution testing of nanocrystals, UV imaging, was introduced and applied in order to obtain detailed understanding of the real-time dissolution behavior of different nanosized particle fractions. Moreover, both liquid and solid nanocrystal dosage forms were formulated and studied in vitro and in vivo. High-quality nanocrystal suspensions were prepared using the rapid and industrially relevant top-down wet milling technique. Detailed, real-time dissolution analyses of the nanocrystals enabled a close level insight into the occurring phenomena. With regards to the formulation development, an in vivo effective nanocrystal suspension formulation was developed for ocular delivery, to treat elevated intraocular pressure. Furthermore, nanocrystal suspensions were converted into dry powders, by both freeze-drying and granulating technique, and further processed into tablet and capsule formulations. By screening both powder and tablet properties, optimal compositions for nanocrystalline solid formulations were indicated with regards to the higher scale process-ability. The formulations were studied both in vitro and in vivo. As a result, the great difficulty of predicting the in vivo behavior based on the in vitro results and the importance of in vivo studies in the early development phase, were addressed. It was concluded that the methods applied and studied provided valuable knowledge and important tools for the pharmaceutical formulation development in order to solve the current problems related to the delivery of poorly soluble drugs.
  • Gu, Yuexi (Helsingin yliopisto, 2015)
    Women with germline mutations of BRCA1 gene are predisposed to the development of basal-like breast cancer, which is characterized by the absence of the hormonal and growth factor receptors, ER, PR and HER2. Mutation of BRCA1 predicts increased sensitivity to certain DNA-damaging agents, e.g. PARP inhibitors and cisplatin. Yet in clinical trials, some BRCA1-mutant breast tumors show resistance to these drugs. Therefore, it is necessary to understand the molecular mechanisms of the acquired resistance and identify novel therapeutic targets for the treatment of those tumors. In order to better understand the biology of breast cancers caused by BRCA1 mutations, we collected and characterized four BRCA1-mutant breast cancer cell lines as surrogates of BRCA1-mutant tumors. Together with several cell lines expressing wildtype BRCA1, we tested their sensitivities to a panel of DNA-damaging agents. We also carried out a high-throughput chemical compound screen on the BRCA1-mutant and BRCA1-wildtype cell lines, and performed a proteome profiling assay to test the kinase activities of those cell lines. Our results reveal extensive heterogeneity among the BRCA1-mutant breast cancer cell lines, which showed resistance to DNA-damaging agents. Then we created isogenic MDA-MB-231 cells with or without BRCA1 depletion by siRNA transfection, and carried out a high-throughput chemical compound screen on the pair of cells in order to identify potential targets that are synthetically lethal with BRCA1 deficiency. Two proteasome inhibitors, bortezomib and carfilzomib, were found to be able to selectively kill BRCA1-depleted cells. Further studies on mechanisms demonstrate that the proteasome inhibitor bortezomib does not induce DNA damage; rather it inactivates G1 cell cycle checkpoint in BRCA1-deficient cells and leads to the accumulation of these cells at G2/M phase. This is caused by inactivation of the retinoblastoma protein (Rb) through its hyperphosphorylation, which in turn activates its downstream transcription factor E2F1. In addition, bortezomib causes compromised G2/M cell cycle checkpoint in BRCA1-deficient cells, which drives cells to enter mitosis and leads to apoptosis due to uncontrolled cell division. In order to investigate the mechanisms underlying the consistent basal-like phenotype of breast tumors associated with BRCA1 mutations, we established an in vitro assay to study the transition of mouse mammary epithelial cells from luminal to basal lineages. Our results showed that loss of BRCA1 promotes basal-like differentiation by sustaining ΔNp63 activity. In luminal cells, ΔNp63 is not expressed or remains inactive through localization in nucleoli. Depletion of BRCA1 leads to translocation of ΔNp63 into nucleoplasm and promotes transition of luminal cells into a basal state. This study provides a potential link between BRCA1 loss and the basal-like differentiation, which may help to explain why BRCA1-mutant breast cancer tends to bear a basal-like phenotype.
  • Hamberg, Leena (Helsingin yliopisto, 2015)
    Flyktingintroduktionen i Sverige präglas av den s.k. arbetslinjen, dvs. strävan efter ett snabbt inträde på arbetsmarknaden och egen försörjning för de nyanlända. Den här studien visar att ambitionerna med arbetslinjen kan komma att skymma sikten för annat väsentligt. Detta gäller inte minst individers språkutveckling och kraven på språkliga färdigheter i arbetslivet. Blundar man för komplexiteten i språkfrågan, finns det risk för att arbetslinjen vänds till en nackdel för de nyanlända. Den här fallstudien som mynnar ut i nämnda farhåga granskar Resursen, en kommunal gränsaktivitet i Sverige. Gränsaktiviteten formas genom att tre aktivitetssystem Arbetsmarknadsåtgärder, Flyktingintroduktion och Svenskundervisning för invandrare bildar nätverk för att genom sina respektive uppdrag bistå en grupp unga nyanlända under målgruppens första tid i Sverige. Undersökningen tar fasta på tidigare forskning som poängterar vikten av språkanvändning i (mötet mellan) aktivitetssystem. Genom en lexikogrammatisk analys av språkbruket i Resursen spåras konstruktionen av gränsaktiviteten. Av särskilt intresse är hur bilden av de nyanlända konstrueras och hur målen för respektive aktivitetssystem samsas inom ramen för gränsaktiviteten. Materialet för analysen består av skriftliga dokument som korsar gränserna mellan systemen och av intervjuer med tjänstemän i gränsaktiviteten. Det visar sig att bilden av de nyanlända varierar beroende på typ av text. De nyanlända konstrueras dels som en lyckosam grupp som fått chansen att komma närmare arbetsmarknaden i Sverige, dels som en administrativ angelägenhet för de samverkande tjänstemännen och dels som aktiva görare som formar gränsaktiviteten till en succé. Av de tre aktivitetssystemen konstrueras Arbetsmarknadsåtgärder som den dominerande parten. Dominansen blir särskilt tydlig vid formuleringen av målen för gränsaktiviteten där snabbt inträde på arbetsmarknaden och egen försörjning betonas. Bland de tjänstemän som arbetar närmast målgruppen höjs det dock röster för alternativa mål såsom ett självständigt liv och personlig utveckling för de nyanlända. Diskussionen om språkutveckling blir däremot knapphändig och endimensionell. Det svenska språket tas som ett självklart redskap för arbetslinjen, av detta material att döma för självklart för att problematiseras. I de fall frågan kommer upp tenderar den att begränsas till utveckling av det talade språket. Detta riskerar inte bara uppfyllelsen av de breda målen för språkutbildningen. I slutändan kan det motverka även det primära målet med arbetslinjen. Här har språkutbildningen ett uppdrag: att sprida kunskap om språkutvecklingen, om språkets roll vid delaktighet i olika sammanhang och inte minst om arbetslivets krav på språkliga färdigheter.
  • Xiong, Jie (Helsingin yliopisto, 2015)
    A general inductive probabilistic framework for clustering and classification is introduced using the principles of Bayesian predictive inference, such that all quantities are jointly modelled and the uncertainty is fully acknowledged through the posterior predictive distribution. Several learning rules have been considered and the theoretical results are extended to acknowledge complex dependencies within the datasets. Multiple probabilistic models have been developed for analysing data from a wide variate of fields of application. State-of-art algorithms are introduced and developed for the model optimization.
  • Jalava, Lotta (Helsingin yliopisto, 2015)
    The dissertation consists of four academic articles and an introductory chapter explaining the objectives, background and results of the study. It concentrates on the variation and change in predicate structures in Tundra Nenets, a Samoyedic (Uralic) language spoken in Siberia. The focus of the study is on the finite and non-finite forms and the concept of finiteness in grammatical change. The study investigates those grammatical categories that show variation in verbal and non-verbal predication or that are results of grammaticalization processes that include changes in non-finite verb forms. The topics of the articles are adjectival words, modal and evidential categories, and the essive-translative constructions in Tundra Nenets. The data consists of published texts in Tundra Nenets from different periods of time representing different genres, as well as fieldwork material recorded on the Taimyr Peninsula in 2011. The approach is functional typological, and the methodology combines synchronic linguistic description and diachronic explanation of the grammatical phenomena. The linguistic processes are analysed with relation to language use and context, and their development is explained with relation to the synchronic variation in the language and similar structural and functional paths of change in other languages. The findings of this study complement earlier research by suggesting mechanisms and paths of change for categories whose origin has been hypothesized in earlier studies. The results suggest that non-finite verb forms often serve as a basis for modal and evidential verb forms in Tundra Nenets, but they can also take part in grammaticalization processes that produce nominal categories, such as the essive-translative suffix. At the same time, the study provides syntactic analyses of lesser studied grammatical categories in Tundra Nenets. It also contributes to the more general discussion on finiteness and infiniteness as well as the division of main word classes in grammatical change.
  • Karjalainen, Erno (Helsingin yliopisto, 2015)
    This thesis combines anion responsive polymeric ionic liquids (PILs) with thermoresponsive polymers. The polymers have been synthesized with controlled radical polymerization methods. A water-insoluble PIL was used as a macro-chain transfer agent in synthesis of block copolymers with poly(N-isopropyl acrylamide) (PNIPAm). PNIPAm chains of various lengths were grown to the same PIL-block. These polymers show a lower cirical solution temperature (LCST) type behavior, typical to PNIPAm. The PIL block and the PNIPAm block interact strongly, no phase transition can be observed for the block copolymers with short PNIPAm chains. The block copolymers form complex aggregates in water. The hydrophobic PIL-homopolymer can be used to make stable particles in salt free water. Also triblock copolymers with a long central PNIPAm block and short water soluble PIL blocks were synthesized. These polymers also show interactions between the PIL and PNIPAm blocks. This can be seen for example as reduced enthalpy of phase transition for the triblock copolymers compared to the PNIPAm homopolymer. The triblock copolymers form complex aggregates at elevated temperatures. The LCST-type phase transtiton of weakly cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) can be modified with bis(trifluoromethane)sulfonamide (NTf2) ions. The presence of NTf2 induces also an upper critical solution temperature (UCST) type transition for PDMAEMA, if the polymer is charged enough. NTf2 turns PDMAEMA to a stronger base, presumably due to the effective screening of charges. NTf2 induces an UCST-type transition for strong polycations in the presence of an added electrolyte. The phase behavior of the polycation-NTf2 system can be influenced by addition of sodium chloride. Similar transition can also be induced by trifluoromethanesulfonate (OTf), though OTf is needed in much higher concetrations. This allows the use of OTf as the only salt. The NTf2-polycation interactions influence the phase behavior of copolymers of N-isopropyl acrylamide (NIPAm) and strongly cationic (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA). With low AMPTMA content, the copolymers show LCST-type behavior in the presence of NTf2 and a copolymer with high AMPTMA-content shows UCST-type behavior. If NIPAm and AMPTMA are copolymerized in nearly equal amounts, both transitions may coexist.
  • Kaukomaa, Timo (Helsingin yliopisto, 2015)
    This study examines facial expressions in naturally occurring face-to-face interaction. The focus is on how facial expressions (e.g., smiles and frowns) are part of the collaborative construction and modification of shared emotional stances between speakers and hearers. The data corpus of this study consists of five recorded dyadic Finnish conversations over lunch between individuals who were familiar with each other. The conversations were recorded with three video cameras: two cameras recorded the participants facial expressions and upper bodies and one camera the overall situation. The method of this study is conversation analysis, which makes it possible to examine how participants use their facial expression, move-by-move or turn-by-turn, in the joint negotiation processes of shared emotional stances. The dissertation consists of three original articles and an introduction. In the introduction, I lay out the central concepts and the perspective of the study, describe the data and method, and provide an overview and short examples of the results of the study. I also discuss at a more general level the ways in which my study contributes to earlier studies on embodied socio-emotional communication, and to our understanding of social interaction and social life. The analysis highlights the important role facial expressions have in construction and modification of the public emotional sphere of conversation. The emotional sphere is in continuous transformation, as the participants collaboratively negotiate their situational relationship and interpersonal (in)congruence with regard to the activity at hand. The articles 1 and 2 examine how speakers turn initial facial expression (a smile or a frown) contributes to the action of the utterance it foreshadows and to the larger sequential environment. The results show that the interactional trajectories of these turn-opening facial expressions vary substantially: smiles are first steps to a shared moment of positive or humorous stance, whereas frowns initiate a problem turn that creates momentary distance between participants. The article 3 demonstrates the ways in which recipients facial expression may shift the emotional stance of the speaker s utterance. The recipient s facial expressions play a major role in the collaborative modification of shared emotional stance. They do not simply mirror the speaker s stance or display understanding of the speaker s talk; rather, they perform well-timed systematic operations on the projected course of the talk. The contribution of the article is to show how speakers and hearers work in collaboration using subtle and well-timed facial (and other) expressions of emotion in order to negotiate, move-by-move, the emotional stance(s) that they will share. This study reveals the significance of facial expressions in communicative actions and in the regulation of situational affective relationship between speakers and hearers in mundane interactions. These processes resonate with the larger social structures and the reproduction of micro-social order.
  • Pukkila, Veera (Helsingin yliopisto, 2015)
    The worldwide use of pesticides (herbicides, insecticides, and fungisides) currently amounts to 2.4 billion kilos. Only a small proportion of pesticides actually reach the target organism, whereas the majority becomes a potent contaminant that threatens the environment and humans. Microbes, present everywhere in the environment, have the ability to degrade many kinds of man-made chemical compounds, xenobiotics. By studying the degrading microbes and the optimal conditions for microbial degradation, bioremediation techniques may be developed to clean contaminated sites. A metabolite of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), is 2,6-dichlorobenzamide (BAM). BAM is frequently detected in groundwater worldwide, and thus the use of dichlobenil is nowadays banned in the EU. Dichlobenil is degraded in soil relatively quickly, but BAM is much more persistent. Due to its high water solubility and low sorption affinity, BAM easily leaches down to deeper soil layers and even to groundwater where it is considered stable. This study focused on the degradation of dichlobenil and BAM in Finnish groundwater sedimentary deposits and topsoil. The biotic and abiotic factors associated with effective dichlobenil or BAM degradation were studied. The aim was to examine how the presence of microbes and oxygen, and the chemical characteristics of soil and groundwater deposits, affect the degradation rates of dichlobenil and BAM. In addition, the indigenous microbes degrading these compounds were enumerated, and some were isolated and identified. Dichlobenil was degraded in all studied groundwater sedimentary deposits and topsoil. The presence of microbes and oxygen, and high carbon and nitrogen contents enhanced dichlobenil degradation. As expected, BAM was more resilient to microbial degradation than dichlobenil. Significant aerobic microbial degradation of BAM was detected only in one out of five deposits, and in another weak biodegradation was observed. In these two deposits the concentrations of the elements manganese, zinc, cobalt, lead, and nickel were high. Aerobic bacterial strains growing in the presence of dichlobenil or BAM were isolated from all studied groundwater sedimentary deposits and topsoil. The isolates belonged to the phyla Proteobacteria, Actinobacteria, and Bacteroidetes, Gammaproteobacteria being the largest group of isolates. The dichlobenil or BAM degradation capacity of the isolates was rather low (5-46%) and not demonstrated for all isolates. In conclusion, the diversity of dichlobenil and BAM degrading aerobic microbes in Finnish groundwater sedimentary deposits and topsoil was relatively high. Especially the high number and diversity of isolated BAM degrading strains was unexpected, as only few BAM degrading strains have been reported earlier. Due to their low degradation capacity the potential of these isolates in bioremediation is not considered high, but they could be used e.g. to identify the genes and enzymes involved in the degradation of dichlobenil and BAM.
  • Kurko, Terhi (Helsingin yliopisto, 2015)
    Nicotine Replacement Therapy (NRT) products are the most commonly used smoking cessation (SC) pharmacotherapy. This study explored the deregulation of NRT products from pharmacy-only distribution to general sales in Finland which took place in 2006. The overall aim of this study was to assess the reasons for the NRT deregulation and its reflections on SC practices in Finland. NRT deregulation was explored from three perspectives: 1) policy-making; 2) community pharmacists as health care professionals providing guidance on NRT use; and 3) NRT users perceptions of NRT in SC. The NRT deregulation from the policy-making perspective was assessed by inductive content analysis of all the publicly available documents and interviews of 12 Members of the Parliament (Study I). A nationwide representative survey to every second pharmacy owner and staff pharmacist (n=2291) was conducted a year after the deregulation in 2006-2007 (Studies II and III). The NRT users perspective was assessed by inductive content analysis of smokers and quitters postings (n=24 481) in five internet discussion areas in the national SC support Forum, STUMPPI, in 2007-2012 (Study IV). The NRT deregulation was politically communicated as a safe and evidence-informed decision promoting public health by advancing SC in Finland (I). However, two of the most important motives for the deregulation, poor NRT availability and the effectiveness of sole NRT use in SC, were largely based on assumptions instead of scientific evidence. At the time of the pharmacists survey, nearly half of the respondents reported being familiar with the Finnish SC Guideline. The familiarity with the Guideline was directly reflected in the level SC actions taken by pharmacist (II). Due to the NRT deregulation, in particular pharmacy owners , motivation towards counselling NRT customers decreased (III). The analysis of smokers and quitters internet-based discussions (IV) revealed that many Finnish smokers and quitters saw NRT as less important in SC or held negative perceptions towards NRT use. From smokers and quitters perspective, the most highlighted factors of successful quitting were quitters own psychological empowerment and peer support from the discussion community. This study found a great variety of NRT usage patterns. Of these, the most commonly emerged one was the use of lower dosage or shorter period compared with the instructions on NRT use. The findings of this study suggest that the sole increased NRT use may not be so crucial for SC as suggested during the political decision-making process. This study provided also evidence that in Finland NRT products are used in a way which may not be optimal for treatment success. Therefore many smokers and quitters could benefit from personalized support for NRT use which would include behavioural components and a plan for NRT use to optimize the treatment. In future it is important to guarantee that community pharmacist are not lost as an important public health resource to provide such individualized NRT counselling and managing personalized SC plans. In addition, there is a need to develop more advanced SC services fitting to the needs of individual quitters. These services could utilize internet-based services and peer support. The findings of this study highlight the need to further evaluate the public health benefits gained from the deregulation.
  • Lauranto, Yrjö (Helsingin yliopisto, 2015)
    This study examines directivity and imperative clauses (henceforth i-clauses) in Finnish. It consists of 3 publications (P1, P2 and P3). While the theoretical basis of the study is systemic-functional linguistics, use is also made of other approaches. P1 concentrates on the description of the imperative, and, thus, the data consist mainly of intuited examples. Firstly, the Finnish imperative can be regarded as a paradigm consisting of the personal forms of the present. This is reflected in traditional descriptions of the Finnish verb, which treat the imperative as one of the moods. This is referred to as the synchronic-morphological perspective. Secondly, the imperative can be examined from the perspective of interaction and interactional constructions. This is called the diachronic-interactive perspective. P2 investigates the canonical i-clause in everyday conversations between friends and family members. The data consist of approx. 140 conversations or excerpts of conversation. 70 % of the data are telephone conversations. One of the characteristics of the i-clause is that it is employed as a response to what has been said before or as a response to the non-linguistic action that is going on during the conversation. Approx. 63 % of the i-clauses in the data (n = 243) can be considered strongly responsive. Another significant finding is that only 10 % of the i-clauses of the data are interpreted by the participants in the conversations as commands. P2 suggests two ways of defining the notion of a directive. From a wider perspective, directives include not only exhortations to action but also offers and permissions. From a narrow perspective, offers and permissions are excluded because they are used to provide addressees with commodities or to enable them to act in the way they themselves wish. P3 discusses two clause constructions that begin with a finite verb conjugated in the 2nd person of the conditional mood but which do not allow a pronoun functioning as the subject. The data consist of everyday interaction and electronically mediated conversations from the Internet. One of the constructions is clearly an optative structure, whereas the other tends to be used as a persuasive expression. It can thus be seen as a grammaticalization of directivity. The study sheds light on the Finnish i-clause and its use, but also on directivity in general. The results are also of relevance to the teaching of Finnish as a second language. Key words: interactional syntax, interpersonal, imperative clause, morphological imperative, everyday conversations, directives, directivity, grammatical metaphor, optative, persuasion, grammaticalization, systemic-functional linguistics
  • Xu, Enjun (Helsingin yliopisto, 2015)
    Regulation of cellular homeostasis is crucial for proper development, survival, defense responses, programmed cell death and ultimately survival. Maintaining cellular homeostasis requires tight regulation of multiple highly interactive signaling pathways. The apoplast lies at the frontier between the cell and the environment, where the plant perceives environmental cues. Since the apoplast is also a site for cell-to-cell communication, it has an important role in mediating plant-environment interactions. Reactive oxygen species (ROS) are known as both toxic agents and indispensable signaling molecules in all aerobic organisms. A ROS burst in the apoplast is one of the first measurable events produced in response to different biotic and abiotic stresses, eventually leading to the initiation of signal transduction pathways and altered gene expression. Apoplastic ROS signaling is well known to dynamically coordinate multiple signaling pathways in the activation of defense responses in plants. Dissection of the signaling crosstalk within such a signaling network could therefore reveal the molecular mechanisms underlying defense responses. Treatments with ozone (O3) have been adopted as an efficient tool to study apoplastic ROS signaling. Plants exposed to O3 trigger a ROS burst in the apoplast and induce extensive changes in gene expression and alteration of defense hormones, such as salicylic acid (SA), jasmonic acid (JA), and ethylene. Genetic variation in O3 sensitivity among Arabidopsis thaliana accessions or mutants highlights the complex genetic architecture of plant responses to ROS. To gain insight into the genetic basis of apoplastic ROS signaling, a recombinant inbred line (RIL) population from a reciprocal cross between two Arabidopsis accessions C24 (O3 tolerant) and Tenela (O3 sensitive) was used for quantitative trait loci (QTL) mapping. Through a combination of QTL mapping and transcriptomic analyses in the response to apoplastic-ROS treatment, three QTL regions containing several potential candidate genes were identified in this study. In addition, multiple mutants with varying O3-sensitivities were employed to dissect the signaling components involved in the early apoplastic ROS signaling and O3-triggered cell death. A combination of global and targeted gene expression profiling, genetic analysis, and cell death assays was performed to dissect the contribution of hormone signaling and various transcription factors to the regulation of apoplastic ROS-triggered gene expression and cell death. The contributions of SA, JA and ethylene were assessed through analysis of mutants deficient in these hormones, mutants with constitutively activated hormone signaling and the exogenous application of hormones. Plants with elevated SA levels were found to be associated with an attenuated O3 response, whereas simultaneous elimination of SA-dependent and SA- independent signaling components enhanced the response to apoplastic ROS treatment. JA could act as both a positive and negative modifier of apoplastic ROS signaling, which was enhanced when ethylene signaling was also impaired. However, transcriptome analysis of a triple mutant deficient in SA, JA and ethylene revealed that these hormones signaling only contributed part (about 30%) of early-apoplastic ROS-triggered changes in gene expression, suggesting multiple signaling pathways could be required to regulate the apoplastic ROS response via combinatorial or overlapping mechanisms.
  • Al-Samadi, Ahmed (Helsingin yliopisto, 2015)
    Recurrent aphthous ulcer (RAU) is an ulcerative disease of the oral mucosa characterised by the appearance of ulcerations in the oral mucosa accompanied by an erythematous halo area surrounding the ulcer and showing signs of acute inflammation. While RAU affects approximately 20% of the population globally, its pathogenesis remains poorly understood. Furthermore, most studies concentrate on treatment while few address the pathogenesis of the disease. This project aimed to determine the mechanisms of oral epithelial cell death in RAU, the role of these cells in disease pathogenesis in terms of toll-like receptor (TLR) expression, and the ability of the these cells to produce chemokines, pro-inflammatory cytokines, and antimicrobial peptides. Together these may first aggravate and, then, down-regulate the inflammation and initiate the healing process. For this purpose, we collected 13 aphthae and 11 healthy control biopsies for immunohistochemical staining, immunofluorescence staining, and quantitative PCR. For functional studies, we cultured primary oral keratinocytes and oral squamous cell carcinoma cell-line SCC-25 and tested their responses to different stimuli. Our results highlight the importance of oral epithelial cells in RAU; interestingly, oral epithelial cells in RAU tested positive for apoptosis markers caspase-3, especially at the superficial and spinous layer, and TUNEL, but negative in controls. We also found that TLRs are primarily present in the basal and suprabasal layers of control epithelium, but their expression extends to the superficial layer in RAU epithelium. Additionally, we found significally higher expressions of tumour necrosis factor-α (TNF-α), interleukin-8 (IL-8), IL-17C, and beta defensin 2 (BD-2) in RAU oral epithelium compared with control epithelium. Functional studies on cultured primary oral keratinocytes and SCC-25 supported our results from RAU biopsies since these cells responded to damage-associated molecule patterns (DAMPs), such as self-DNA and pro-inflammatory cytokines including IL-17C, TNF-α, and interferon gamma (IFN-γ), through a significant increase in the expression of selected molecules including TLR2, TNF-α, and BD-2. Based on our findings, RAU may begin with a strong initiating factor activating a self-amplificatory cycle. This cycle is characterised by the induction of epithelial cells apoptosis at the superficial layer down to the basal layer, a change in the pattern of TLR distribution, the up-regulation of several chemokines and pro-inflammatory cytokines, and, finally, the secretion of antimicrobial peptides initating the healing process. As a result of the lack of adaptive immunity in RAU, the cycle recurs when the mucosa is subjected to an initiating factor of the same sequence.
  • Pere, Tuula (Fourth Life Publishing, 2015)
    PROTECTED, TOLERATED OR SANCTIONED FREEDOM OF SPEECH? A legal-historical study on the impact of the social and cultural shift of the 1960 s and 1970 s on the limits of the freedom of speech in mass communication in Finland. This legal historical study looked into the impact of the social and cultural shift in the 1960 s and 1970 s on the limits of the freedom of speech in the Finnish mass media as it was exercised by the press, radio and television. The limits of the freedom of speech were considered in the broad sense of the term, with focus not only on legal regulation and self-regulation but also on the actual limits in exercising the freedom of speech. Mass communication during the shift was represented by strongly opposing ideologies, and it was utilised both in supporting the prevailing hegemony and in toppling it. Mass communication took to supervising the powers of other forces, becoming a social influence a fourth estate even, in some people s view. After the war years, the Finnish society had been rebuilt in a joint effort, improving the situation of its citizens by means of social, health and educational policies and by specifying the practices of the labour market. However, the actual social and cultural shift did not take place until the 1960 s and 1970 s and had to do with the changes in the economic and demographic structures and the emergence of the baby-boom generation as active citizens. Aside from material good, a wider population could now benefit from higher education, which enabled them to climb the social ladder and thus provide them with more influence. The welfare state developed hand in hand with the democratic opportunities of the citizens. A citizen had become interesting both as a voter and a consumer. The volume and technology of communication developed significantly, bringing about a new climate of opinion, which changed people s ideas about the appropriate limits of the freedom of speech. To analyse the judicial shift under study, a contextual legal historical approach was employed. Owing to the nature of the research at hand, connections to the different fields of law and the fields of science are manifold. The study, which falls into the field of law, has points in common mostly with the perspectives of the studies of social sciences, cultural history and social history and history of ideologies. The data gathered from the subject of study have been analysed by linking together previous findings in rarely seen ways. The analysis focused primarily on the national level. The domestic phenomena were closely linked with the equivalent developments of other Western countries the Nordic countries in particular. Moreover, comparisons were made with the developments in the United States, as they influenced the Finnish society as well cf. the peace movement, the women s movement, racial issues, the increasing activism among youth, and the commercial use of the freedom of speech. On the other hand, the international situation of the cold war era, the political pressure coming from the Soviet Union, and the phenomenon of finlandisation, had an impact on the speech and mass communication in Finland. The changes in the Finnish mass communication environment during the shift involved the structures, operating conditions and media contents alike. The transformed attitudes were manifested both in the discussed topics and the manner in which they were discussed. There was an increase in the diversity of opinion, the differences of opinion came to a head, and the media were subjected to both internal and external pressure. Mass communication was actively involved in the social development. Tabloids brought their own flavour to the opposing interests in mass communication, managing successfully to turn the voyeuristic and sensation-seeking behaviour of people into profitable business. As the research progressed, it became evident that if it was still possible to discern some sort of collective idea of the freedom of speech with the advent of the 1960 s, this became increasingly difficult once the shift got properly underway. The old boundaries were pushed both in the political mass communication and politically-oriented entertainment. On the European scale, the Finnish television system was from the very beginning a unique and curious combination of both ideological and commercial elements and players. The coupling of the commercial media with the parliamentary-controlled Finnish Broadcasting Company (Yleisradio) was a difficult political issue right from the early days of Finnish television. In the era of Reporadio, (a pejorative nickname referring to the President of the company at the time) television, the newcomer in the electronic media, brought forth leftist mass communication and entertainment. This was offset by the American-oriented worldview of commercials, series and films. The operating environments for exercising the political freedom of speech and the commercial communications saw a rapid transformation. Finland s location at the interface between the East and the West was also manifested in how two opposing ideologies collided in the Finnish mass media. At the core of the freedom of speech in mass communication in the social and political sphere of mass communication there was a tough ideological battle going on, with the leftist orientation and the even wider bowing to the East not uncommon during the era of finlandisation strongly represented. Besides the leftist party papers and various ideological papers, the leftist tendencies in the press were also represented by a group of radical reporters within the mainstream press. The new practices of mass communication, and breaking the old boundaries in the spirit of a cultural shift, sometimes caused disapproval and backlashes in all areas of communications. Offences against religious and moral beliefs and patriotic feelings became the topic of hot debates and were discussed by the various bodies controlling the use of words by mass media even in the courts of law. The transformed society was coloured by an array of opinions, and the interpretations as to the limits of the freedom of speech varied greatly. New demarcations and supportive regulation thereof were called for. The legal regulation as to how the mass media exercised the freedom of speech did not essentially change during the period under study, leaving the effects of the changes on the everyday life of mass communications rather insignificant as a whole. As for self-regulation, the mass media and advertising aimed proactively and voluntarily to act appropriately in the media. Despite long preparations, numerous law initiatives fizzled out or were only implemented in the decades to come. However, the effort put in the preparation made a difference in the political life and public debate of the era. Advertising was subject to harsh criticism particularly from the left wing and the consumer movement, forcing the legislature and the self-regulatory norms to tighten up, particularly in alcohol and tobacco advertising. Legislative means were also employed for better protection of privacy threatened by the tabloids. The factors most affecting the boundaries of the freedom of speech were seldom discernible in regulatory actions. The actual freedom of speech exercised in mass communication was in some cases wider than the formal regulation, which trailed behind, while in some cases narrower, due to practical operational preconditions or external pressure, for instance. In comparison with the past, freedom of speech as a whole flourished relatively freely, despite the fact that the regulations were not loosened or modernised. It was more about a greater flexibility and tolerance of control and decision-making which aimed to facilitate the releasing of shift era pressures. On the other hand, the political restrictions and self-censorship due to the pressure built up during the period of finlandisation clearly limited the freedom of speech in mass communication.
  • Eskelä, Elina (Helsingin yliopisto, 2015)
    Cities are striving to attract and retain talented workers in order to increase their competitiveness in the new economy, which is highly dependent on innovation and knowledge. Residential satisfaction has been identified as a key determinant of whether a person stays or moves to another location. However, given the tendency to focus on the housing of immigrant groups with a lower socio-economic status, the factors that affect the residential satisfaction of skilled migrants remain understudied. This article-based dissertation in the field of urban geography examines the determinants of residential satisfaction among skilled migrants living in the Helsinki metropolitan area (HMA), Finland. The research setting is intended to maximise the cultural and socio-economic as well as locational diversity within the limits of recognised skilled migrant groups. The analysis focuses on how the interplay between individuals norms and the situational conditions is manifested when immigrants assess a single housing market, the HMA. The study is qualitative in nature and draws on 70 semi-structured interviews with skilled migrants and with experts on migration and housing in the city region. Despite the cultural, socioeconomic and locational heterogeneity of the interviewees, their experiences of housing in the HMA were notably similar: the uppermost assessment was that it is expensive, cramped and uniform. On the other hand, they appreciated the overall safety and functionality of the city region, as well as the natural environment: the predominant influence, for them, is the family life cycle rather than the urban amenities that are often assumed to be highly important for the creative class . The results also show that homeownership is not a simple indicator of the intention to stay in or leave the region, which contradicts earlier findings on ethnic-minority housing. The study underlines the importance of the social environment in creating residential satisfaction among skilled migrants. Whereas earlier studies revealed the essential nature of social networks and personal trajectories in the location decisions of skilled workers, the results of this study indicate that the supply of local, neighbourhood-based social ties is particularly limited in the case of the HMA, and that this has a negative impact on the residential satisfaction of skilled migrants. Furthermore, the structural element of housing seemed to have an effect on local social ties: among international students the extent of such ties varied according to the housing form. Although many skilled migrants are in a good socio-economic position, they are not immune to problems related to finding suitable housing. Housing availability, quality and affordability are therefore significant factors in enhancing residential satisfaction among such groups. Furthermore, as local social ties serve a mediating role with regard to the residential area as well as to society, the formation of such ties would promote the integration of migrants. These aspects of housing should be acknowledged in the strategies of cities wishing to accommodate and retain global talent. Keywords: skilled migrants, housing, residential satisfaction, social ties, Helsinki metropolitan area
  • Ruppel, Meri M. (Helsingin yliopisto, 2015)
    The Arctic has been warming twice as fast as the rest of the world during the last decades of global warming. Reasons for the amplified Arctic warming are thought to partly relate to positive feedbacks affecting the radiative budget of the area. Black carbon (BC) is a light-absorbing particulate produced by incomplete combustion of biomass and fossil fuels. BC strongly warms the atmosphere, and its climate effects are amplified in the Arctic where its deposition on light surfaces decreases their reflectivity, resulting in elevated heat absorption and further hastening melt of snow and ice. Globally, BC is estimated to be the second most important climate-warming agent after carbon dioxide. Historical information on BC deposition plays a significant role in the assessment of long-term climate effects of BC, but scarce data on this past variability has been available from the Arctic. Historical BC records can be attained from environmental archives, such as ice cores, peat deposits and marine and lake sediments, which store direct evidence of past BC deposition in chronological order. The objective of this thesis is to collect new spatial and temporal data on BC deposition in the European Arctic from the preindustrial to the present (i.e., the last ca. 300 years), and assess BC sources and climatic implications, by analysing five lake sediment cores from Arctic Finland and an ice core from Svalbard. No standard method exists to determine BC, and the precise definition of BC depends on the methodology used for its quantification. Here, three different analytical methods were used to quantify different components of BC. Spheroidal Carbonaceous Particles (SCP) and soot-BC (SBC) were analysed from the Arctic Finland lake sediments by SCP analysis and chemothermal oxidation at 375 °C, respectively, and elemental carbon (EC) from the Svalbard ice core with a thermal optical method. The results suggest temporal variation in past BC trends, both between study sites and between methods. While SCPs show a marked trend with fluxes peaking around 1980 and declining afterwards, they represent only a minor fraction of total BC. SBC and EC are better suited to indicate general historical BC trends. SBC fluxes vary between sites but some regional patterns are noticeable. The two northernmost lakes indicate generally decreasing SBC fluxes during the latter half of the 20th century which is in line with previous data from Greenland ice cores, modelling studies and atmospheric measurements. However, two other lake sites indicate increasing SBC fluxes from ca. 1970 to the end of the records, likely caused by local emissions from the Kola Peninsula, Russia. Moreover, an increasing EC deposition trend from ca. 1970 to 2004 is also recorded in the Svalbard ice core. This increasing trend is unexpected and unparalleled among available arctic records. The observed increase in the ice core is likely caused by flaring emissions from northern Russia. The fact that a similar trend in BC fluxes and deposition is recorded in two separate environmental archives analysed with different methods and receiving atmospheric transport from mostly different source areas, highlights the plausibility of such a trend, and implies that it may also be observable at other locations in the Arctic. In such a case, BC may have exerted a significant impact on the radiative forcing and thereby past climatic warming of the Arctic, in the most recent three or four decades. However, the present study indicates that local results cannot necessarily be extrapolated over wider areas, and therefore further studies are required to establish regional BC deposition trends within the Arctic. In addition, the study highlights that BC results obtained using different analytical methods should be compared with caution.