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  • Suomalainen, Juha (Helsingin yliopisto, 2006)
    Due to the recent development in CCD technology aerial photography is now slowly changing from film to digital cameras. This new aspect in remote sensing allows and requires also new automated analysis methods. Basic research on reflectance properties of natural targets is needed so that computerized processes could be fully utilized. For this reason an instrument was developed at Finnish Geodetic Institute for measurement of multiangular reflectance of small remote sensing targets e.g. forest understorey or asphalt. Finnish Geodetic Institute Field Goniospectrometer (FiGIFiGo) is a portable device that is operated by 1 or 2 persons. It can be reassembled to a new location in 15 minutes and after that a target's multiangular reflectance can be measured in 10 - 30 minutes (with one illumination angle). FiGIFiGo has effective spectral range approximately from 400 nm to 2000 nm. The measurements can be made either outside with sunlight or in laboratory with 1000 W QTH light source. In this thesis FiGIFiGo is introduced and the theoretical basis of such reflectance measurements are discussed. A new method is introduced for extraction of subcomponent proportions from reflectance of a mixture sample, e.g. for retrieving proportion of lingonberry's reflectance in observation of lingonberry-lichen sample. This method was tested by conducting a series of measurements on reflectance properties of artificial samples. The component separation method yielded sound results and brought up interesting aspects in targets' reflectances. The method and the results still need to be verified with further studies, but the preliminary results imply that this method could be a valuable tool in analysis of such mixture samples.
  • Haapamäki, Ville (Helsingin yliopisto, 2004)
  • Bensch, Frank (Helsingin yliopisto, 2012)
    Serious injuries of the spine and pelvis are common in level I trauma centers, and are usually the result of high-energy accidents such as motor vehicle accidents (MVA) or falls from a height, but increasingly also sports and recreational accidents. Even presumably minor accidents can result in serious injury depending on the injury mechanism. The risk of acquiring a fracture is also tied to possible predisposing factors such as a weakened bone structure in osteoporosis, or an increased stiffness of the spine in ankylosing spondylitis. ----- Spinal injuries have a potential for catastrophic, life-altering consequences, because they are associated with spinal cord injury (SCI). A missed or inappropriately managed spinal injury can result in secondary SCI or progression of the initial damage. But also pelvic fractures pose a serious threat, as there are large-caliber blood vessels, nerves, and the lower urinary tract in close proximity to the pelvic bones. An acute bleeding into the pelvic area can remain clinically silent for an extended amount of time due to circulatory compensation processes. Exclusion of these occult injuries by imaging techniques is therefore imperative in order to detect a serious injury as early as possible and administer appropriate treatment. Time-, space-, and cost restraints as well as the patient s stability limit the application of imaging modalities in the golden hour of trauma resuscitation, which is arguably the most critical phase for the patient s outcome. The optimal choice of imaging methods is therefore crucial. But also the knowledge of injury patterns and demographic risk factors contributes to the correct diagnosis of a serious injury. This thesis focuses on injury patterns of the spine in conjunction with high-energy accidents, as well as demographic patterns and the optimal choice of imaging modality. It consists of five publications with a total of 2375 patients, covering a time frame from January 2001 to September 2009. There is special emphasis on vertebral burst fracture, which is the most common fracture in the thoracolumbar area, and which has furthermore a high potential for SCI due to its unstable nature. Also the bony pelvis as an extension of the spine receives special reference. According to our results, serious spinal injury as a result of blunt trauma occurs in all age groups and independently of gender, and even minor trauma energies can result in serious trauma. Trauma energy does have an influence though, as the incidence of spine fractures increases with increasing falling height, and burst fractures and spine fractures on multiple levels become more frequent. But also other blunt trauma mechanisms had multiple spine fractures in up to 32 % of cases, whereof 29 % were non-contiguous. Burst fracture was seen on multiple levels in 10 % of cases, with 50 % being non-contiguous. The frequent occurrence of vertebral fractures and especially burst fractures on non-contiguous levels makes imaging of the whole spine necessary in conjunction with high-energy accidents, especially in obtunded patients. Radiography demonstrates unstable vertebral fractures with acceptable accuracy, particularly in the lumbar spine (LS). Summation of overlapping tissue in these areas makes the identification of the hall marks of an unstable facture difficult, which can lead to an injury being missed, or wrongly classified as stable. Neurological deficit was most frequent and serious in the CS. In the pelvic area, radiography detected only 55 % of fractures diagnosed by multidetector computed tomography (MDCT), and in 11 % findings were false negatively normal. Additionally, Tile classification of fractures was correct in 59 % of injuries, whereas the subtype was correct in only 14 %. The pelvis was false negatively classified as stable in 40 % of cases. Sport and recreational accidents had an overall incidence of injury of one in five, of which 71 % were considered to be serious. The three most common types of serious injury were intracranial injury, fractures of facial bones, and vertebral injuries. The most common accident mechanisms were bicycling, horseback riding, and team ball sports, with bicycling causing most frequently serious injury. In conclusion, it is recommended using MDCT to rule out serious injury of the spine and pelvis in adult victims of high-energy accidents of all age groups and both genders, especially in regard to multilevel injuries and injuries of the cervical spine. Even in presumably minor trauma, a high level of suspicion is required, and MDCT should be employed if the clinical finding is uncertain. MDCT is fast, cost-effective, and demonstrates injuries of the spine and pelvis unambiguously, benefiting the trauma patient s outcome.
  • Kuikko, Janne (2008)
    The investment atmosphere has changed significantly due to the European integration that took place in the 21st century. Thus there has been a need to chart the prevailing risks more carefully. Special attention has been given to risk measures in particular. The focus has been especially on static risk measures, since significant problems have been detected in the application of dynamic risk measures. Attention is paid also on the coherency of risk measure, and the terms of a coherent risk measure are determined. We will adopt a mean-variance approach in this study because it is still common to use the portfolio variance (standard deviation) as a measure for risk, although the concept of market portfolio dating back to the times of Harry Markowitz has been perceived as too much of a sweeping single variable that would hold all risk information occurring in the prevailing market. So models, which use several different variables for measuring risk have been developed. These models attempt to “suck in” exhaustively all risk-information available in the market. Arbitrage Pricing Theory (APT) functions as a starting point. APT is in principle the first multi-factor model introduced, but it presents the used variables in a very limited manner. Later on, the qualifiers in multi-factor models have been specified, and special attention has been given to defining and choosing the variables. Various theories, which try to model the real activities of the finance market, have been used to justify the choice of variables. Hence, multi-factor models concentrate above all on the choice of variables. These variables have mainly been chosen according to macroeconomic, fundamental and statistical grounds. Macroeconomic models concentrate on explaining the dependency between external forces of the economy and asset returns. Fundamental models on the other hand believe that asset returns are determined mainly based on company-specific factors, and statistical models estimate variables from the historical return development of a single asset. Two fundamental models are described more carefully, a 3-factor model by Fama and French (1993) and a 4-factor model by Carhart (1997). By comparing the explanatory powers of these three different models we can deduct which model can best explain the asset returns and consequently the risk it includes. Connor (1995) gives a thorough study on the explanatory power of these models. After this, by comparing each of them separately with Capital Asset Pricing Model (CAPM) we can discover the optimal risk management instrument. This specific comparison is done by Fletcher and Hillier (2002). The basic idea is therefore to study whether the variables used in multi-factor models include some additional information that single variable models cannot explain. Finally we end up with the conclusion that in certain conditions and with certain restriction, very realistic ones though, the explanation power of a multi-factor models is greater than in single-factor model (CAPM). Thus they include additional information about the prevailing risk compared to single-factor model and give more realistic, detailed and more reliable description of the risk involved with the asset or a portfolio.
  • Kopp, Christine (2006)
    Tutkimuksen tarkoituksena oli tehdä morfologinen kartoitus ayrshire-rotuisella keinosiemennyssonnilla esiintyneistä siittiövioista. Tutkimuksessa oli mukana tapaussonnin lisäksi joukko normaaleja iältään ja rodultaan tapausta vastaavia kontrollisonneja sekä osassa tutkimusta kivesnäytteitä Sertoli cell only -oireyhtymästä kärsineestä sonnista. Giemsalla värjätyistä siemennäytteistä ja HE-värjätyistä kivesleikkeistä selvitettiin kuva-analyysin avulla kiveskudoksen histologisia ominaisuuksia sekä ejakulaatissa esiintyvien solujen rakennetta ja kokoa. Lisäksi tapaussonnilla ejakulaatissa esiintyvät epämuodostuneet siittiöt jaettiin neljään eri ryhmään pään ja hännän rakenteellisten ominaisuuksien mukaan. Kivesnäytteille tehtiin immunohistokemiallinen vimentiinivärjäys Sertolin solujen osoittamiseksi ja fluoresenssivärjäyksiä siemennäytteille osoittamaan sekä kromatiinin että mitokondrioiden jakautumista ejakulaatissa esiintyvissä soluissa. Tutkimuksessa saatujen tulosten perusteella voitiin osoittaa, että tapaussonnilla ei esiintynyt lainkaan rakenteeltaan normaaleja siittiöitä ja kaikki sen siittiöt olivat liikkumattomia. Lisäksi kudostasolla siittiönkehitys oli häiriintynyt selvästi kivesten siementiehyiden tubuluksissa jo spermatosyyttivaiheesta alkaen. Histologinen kuva poikkesi tapaussonnilla selvästi normaaleista kontrollieläimistä eri kehitysvaiheissa olevien siittiöiksi muodostuvien solujen lukumäärien progressiivisesti vähentyessä siittiönkehityksen edetessä. Sertolin solujen lukumäärä puolestaan oli tapauksella huomattavasti kontrollisonneja suurempi. Useimmat tapauksen siittiöistä olivat monihäntäisiä, häntien lukumäärän vaihdellessa yhdestä yli kymmeneen. Fluoresenssivärjäykset osoittivat tapaussonnin siittiöiden olevan useimmiten monitumaisia. Tutkituissa siittiöissä tumia oli 1–6. Mitokondrioita siittiöiden keskikappaleissa esiintyi vain satunnaisesti. Kirjallisuuskatsausosassa käsitellään normaalia siittiönkehitystä ja siittiönkehityksen häiriöitä sekä esitellään tapaussonnin siittiövikojen kaltaisia humaanitapauksia.
  • Järvelä, Emilia (2014)
    High-energy γ-rays produced by powerful relativistic jets are usually associated with blazars and radio galaxies. Recently Fermi/LAT detected γ-rays from a few Narrow-Line Seyfert 1 galaxies and thus confirmed the presence of relativistic jets in those sources. In the current AGN paradigm powerful relativistic jets are almost exclusively launched from massive elliptical galaxies. Since NLSy1s are young evolving AGN they offer a unique opportunity to study the production of rela- tivistic jets in late-type galaxies. In this study our aim is to determine via which processes and where different kinds of radiation are produced in NLSy1s. We compiled the so far largest multiwavelength database of NLSy1s which allowed us to explore correlations between different wavebands. We did this separately for radio loud and radio quiet sources. Multiwavelength correlations indicate that radio loud sources host a jet whereas radio quiet sources do not or the jet is very weak. Kolmogorov-Smirnov test suggests also that radio quiet and radio loud sources have different parent populations in redshift, luminosity and black hole mass. Open questions aroused also by this study are e.g. the origin of the infrared emission in NLSy1s and the differences between radio quiet and radio loud sources. In the future the large multiwavelength database of NLSy1s will permit us to easily identify and compare properties of new γ-ray NLSy1s to be detected by Fermi or other facilities.
  • Aalto, Antti (Helsingin yliopisto, 2010)
    Double-stranded RNA and associated proteins are known to regulate the gene expression of most eukaryotic organisms. These regulation pathways have different components, outcomes and distinct nomenclature depending on the model system, and often they are referred to collectively as RNA silencing. In many cases, RNA-dependent RNA polymerases (RdRPs) are found to be involved in the RNA silencing, but their targets, activities, interaction partners and reaction products remain enigmatic. In the filamentous fungus Neurospora crassa, the RdRP QDE-1 is critical for silencing of transgenes a phenomenon known as quelling. In this thesis the structure, biochemical activities and biological functions of QDE-1 were extensively studied. This dimeric RdRP was shown to possess five distinct catalytic in vitro activities that could be dissected by mutagenesis and by altering reaction conditions. The biochemical characterization implied that QDE-1 is actually an active DNA-dependent RNA polymerase that has additional RdRP activity. It also provided a structural explanation for the dimerization and suggested a biological framework for the functions of QDE-1 in vivo. (I) QDE-1 was also studied in a broader context along with the other components of the quelling pathway. It was shown that DNA damage in Neurospora causes a dramatic increase in the expression level of the Argonaute protein QDE-2 as well as the synthesis of a novel class of small RNAs known as qiRNAs. The accumulation of qiRNAs was shown to be dependent on several quelling components, and particularly to be derived from an aberrant ssRNA (aRNA) molecule that is synthesized by QDE-1 in the nucleus. The genomic distribution of qiRNA targets was analyzed and the possible biological significance of qiRNAs was studied. Importantly, qiRNAs are the first class of small RNAs that are induced by DNA damage. (II) After establishing that QDE-1 is a multifunctional RNA polymerase with several activities, template specificities and subcellular locations, the focus was turned onto its interaction partners. It had been previously known that QDE-1 associates with Replication Protein A (RPA), but the RecQ helicase QDE-3 was now shown to regulate this interaction. RPA was also observed to promote QDE-1 dependent dsRNA synthesis in vitro. By characterizing the interplay between QDE-1, QDE-3 and RPA, a working model of quelling and qiRNA pathways in Neurospora was presented. (III) This work sheds light on the complexity of the various RNA silencing pathways of a fungal model system. It shows how an RdRP can regulate gene expression on many levels, and suggests novel lines of research in other eukaryotic organisms.
  • Masche, Philipp (Helsingin yliopisto, 2004)
  • Lindholm, Anne (2015)
    Multilingualism and multiculturalism are very common phenomena in the global world of today. People move into other countries and integrate in other cultures more than ever before. This Master´s Thesis is a qualitative study on how multilingual people describe their linguistic and cultural identity and how it is to be a minority within the Swedish-speaking minority in Finland. The aim of this study is to increase the knowledge and understanding on people who represent a linguistic minority in the Swedish-speaking linguistic minority in Finland and how they describe their linguistic and cultural identity. The scientific approach of the study is phenomenological, which means that the study aims to describe the phenomenon of multilingualism, multiculturalism and integration based on informants' subjective experiences. Nine people were interviewed for this study, and the collected data were analysed using content analysis. All nine informants were living in the capital area of Finland when the interviews were done, but are born in another country. The results of this study demonstrate the significance of language and culture for a person’s identity. The linguistic and cultural identities form during the entire course of life and can be seen as a lifelong process.
  • Hirvonen, Maija (Helsingin yliopisto, 2014)
    The present dissertation analyses the representation of space in filmic audio description. The main objective of this study is to shed light on two critical challenges for audio description: (1) how the filmic space becomes audible in audio-described film through spoken language, sound effects, and music, and (2) how the visual representation of space in film can be cued by the linguistic mode in an audio description. This dissertation consists of four articles and a thesis summary. The first article focusses on the multimodal representation of space through auditory cues. The other three articles explore intermodal similarity, which involves the question of how language reflects visual representation. To explain the complex phenomenon of translating images into words, this study applies the theoretical and analytical tools from translation studies, film studies and cognitive linguistics, and also adopts a cognitive orientation to explain both the filmic and linguistic representations as being cognitive representations that are constructed through visual, auditory, and linguistic cues. This research first establishes that the auditory multimodality of an audio-described film creates a variant of the multimodality of the audiovisual film that entails dynamic constellations, perspectives and foci. Secondly, the analysis presents evidence for the varied potential of the linguistic mode in terms of representing space. Thirdly, this study defines strategies for intermodal similarity in terms of the corresponding linguistic signs for the filmic cues of representation and narration. The results of this dissertation may be valuable in justifying the consistency and standards for audio description as well as in developing other, more far-reaching usages of audio description as a mode of transforming information from one system of representation into another.
  • Piipponen, Tiia (2014)
    Tämän tutkielman tarkoituksena on antaa lukijalle pohjatiedot bayesilaisesta tilastollisesta päättelystä. Tutkielmassa esitellään kaksi usein bayesilaisessa päättelyssä käytettävää todennäköisyysjakaumaa: diskreetti multinomijakauma ja jatkuva Dirichlet-jakauma. Tutkielmassa tutustutaan jakaumien soveltamisen kannalta keskeisimpiin ominaisuuksiin. Lisäksi jakaumien yhteisjakauma Dirichlet-multinomijakauma esitellään. Tilastollisen päättelyn tarkoituksena on tehdä havainnon perusteella johtopäätöksiä mittaamattomista suureista. Bayesilainen päättely sallii arvioitavaan suureeseen kohdistuvien ennakkotietojen huomioonottamisen päättelyprosessissa. Priorijakauma sisältää ennakkokäsitykset arvioitavasta suureesta. Uskottavuusfunktio on puolestaan havainnon todennäköisyysjakauma. Ennakkotieto ja havainnosta saatava tieto voidaan yhdistää Bayesin kaavalla ja näin priorijakauma päivitetään posteriorijakaumaksi. Johtopäätökset tehdään posteriorijakaumasta. Bayesilainen päättely vaatii paljon numeerista integrointia ja sen suosio on kasvanut tietoteknisen kehityksen myötä. Sitä sovelletaan nykyään monilla eri tieteenaloilla. Tutkielmassa käsitellään sitä, kuinka multinomijakaumasta poimitun havainnon perusteella voidaan estimoida multinomijakauman parametreja bayesilaisin menetelmin. Tästä annetaan esimerkki. Dirichlet-multinomijakaumaa voidaan soveltaa esimerkiksi bayesilaisessa mallivertailussa ja myös tästä annetaan käytännön esimerkki. Tutkielman sisällön ymmärtämiseksi vaaditaan, että lukijalla on pohjatiedot todennäköisyyslaskennan peruskäsitteistä. Lisäksi joukko-opilliset operaatiot ja tärkeimmät kuvauksiin, differentiaali- ja intergaalilaskentaan liittyvät asiat oletetaan tunnetuiksi. Tutkielmassa tehdään vertailua bayesilaisen ja frekventistisen tilastollisen päättelyn välillä ja oletetaan, että lukija tuntee frekventistisen tilastollisen päättelyn perusmenetelmät.
  • Laitinen, Klas (2014)
    International commercial arbitration is the de facto method of solving disputes between corporations. Multi-party and multi-contract arbitration situations have increased significantly in recent years, which has led to arbitration institutes creating new mechanisms to increase efficiency in such situations. However, these new rules have not been studied in-depth and compared to each other, to ascertain possible similarities, dissimilarities, and common requirements. This thesis examines joinder, intervention, and consolidation mechanisms at five international arbitration institutes (ʻthe FAIʼ is the Arbitration Institute of the Finland Chamber of Commerce, ʻthe SCCʼ is the Arbitration Institute of the Stockholm Chamber of Commerce, ʻThe ICCʼ is the International Chamber of Commerce International Court of Arbitration, ʻThe HKIACʼ is the Hong Kong International Arbitration Centre, and ʻthe SCCAMʼ is the Swiss Chambers of Commerce Association for Arbitration and Mediation) to ascertain common requirements, and effects on the fairness, efficiency, and economy of international commercial arbitration. This thesis finds that the solutions chosen at the studied institutions are largely similar in theory and in practice. There are four common requirements: 1) the consent requirement meaning that party consent is demonstrable both in cases with many agreements, and in cases with non-signatories as potential parties; 2) the timing requirement meaning that the earlier in the process the request is made by a party, the more likely it is to succeed. Different institutions have different deadlines for involuntary consolidation, joinder, and intervention; 3) the connectivity requirement meaning that there needs to be a certain degree of similarity between cases and/or parties. The connectivity requirements in relation to multi-party and multi-contract mechanisms differ among institutions studied; 4) the procedural efficiency requirement meaning that, in addition to fulfilling the other requirements, the request must also enhance procedural efficiency of the process or benefit the institution in some way. Three of five institutions studied have chosen mostly similar rules; the ICC, the FAI and the HKIAC are almost identical in their treatment of multi-party situations. Therefore, they are considered by this thesis to be the new international standard. The SCC is significantly more restrictive than ICC, FAI and HKIAC in allowing involuntary mechanisms. The SCCAM is most liberal of institutes studied, and allows arbitrators a significant amount of freedom, at the cost of party autonomy and confidentiality, to allow third-parties to intervene in arbitration proceedings, whether the third-party is directly involved in the dispute or not. The findings of this thesis show that multi-party and multi-contract mechanisms may increase the effectiveness of international arbitration at a cost to party autonomy. Party autonomy is limited by arbitration institutions nominating all arbitrators in multi-party disputes, and allowing involuntary transformation of bi-party disputes into multi-party disputes through the mechanisms of joinder, intervention, and consolidation. The increased efficiency is however limited to bi-polar multi-party proceedings and is ill equipped to handle multi-polar arbitration proceedings. The choice of an arbitration institution and consequently the process that institution follows involves significant risks, such as longer processes, and additional costs for corporations. Multi-party mechanisms, by themselves, do not significantly enhance the attractiveness of Finland as a seat of arbitration. However, this thesis finds that they are necessary first step. The conclusions in this thesis are that multi-party mechanisms are a good addition to international commercial arbitration and should be readily adopted by institutionsʼ, but the usage of such mechanisms should only be considered when efficiency gains outweigh the costs to party autonomy.
  • Laaksonen, Elina (Helsingin yliopisto, 2010)
    Socioeconomic health inequalities have been widely documented, with a lower social position being associated with poorer physical and general health and higher mortality. For mental health the results have been more varied. However, the mechanisms by which the various dimensions of socioeconomic circumstances are associated with different domains of health are not yet fully understood. This is related to a lack of studies tackling the interrelations and pathways between multiple dimensions of socioeconomic circumstances and domains of health. In particular, evidence from comparative studies of populations from different national contexts that consider the complexity of the causes of socioeconomic health inequalities is needed. The aim of this study was to examine the associations of multiple socioeconomic circumstances with physical and mental health, more specifically physical functioning and common mental disorders. This was done in a comparative setting of two cohorts of white-collar public sector employees, one from Finland and one from Britain. The study also sought to find explanations for the observed associations between economic difficulties and health by analysing the contribution of health behaviours, living arrangements and work-family conflicts. The survey data were derived from the Finnish Helsinki Health Study baseline surveys in 2000-2002 among the City of Helsinki employees aged 40-60 years, and from the fifth phase of the London-based Whitehall II study (1997-9) which is a prospective study of civil servants aged 35-55 years at the time of recruitment. The data collection in the two countries was harmonised to safeguard maximal comparability. Physical functioning was measured with the Short Form (SF-36) physical component summary and common mental disorders with the General Health Questionnaire (GHQ-12). Socioeconomic circumstances were parental education, childhood economic difficulties, own education, occupational class, household income, housing tenure, and current economic difficulties. Further explanatory factors were health behaviours, living arrangements and work-family conflicts. The main statistical method used was logistic regression analysis. Analyses were conducted separately for the two sexes and two cohorts. Childhood and current economic difficulties were associated with poorer physical functioning and common mental disorders generally in both cohorts and sexes. Conventional dimensions of socioeconomic circumstances i.e. education, occupational class and income were associated with physical functioning and mediated each other’s effects, but in different ways in the two cohorts: education was more important in Helsinki and occupational class in London. The associations of economic difficulties with health were partly explained by work-family conflicts and other socioeconomic circumstances in both cohorts and sexes. In conclusion, this study on two country-specific cohorts confirms that different dimensions of socioeconomic circumstances are related but not interchangeable. They are also somewhat differently associated with physical and mental domains of health. In addition to conventionally measured dimensions of past and present socioeconomic circumstances, economic difficulties should be taken into account in studies and attempts to reduce health inequalities. Further explanatory factors, particularly conflicts between work and family, should also be considered when aiming to reduce inequalities and maintain the health of employees.
  • Jokela, Pia (Helsingin yliopisto, 2012)
    The family Picornaviridae includes many human pathogens. Human enteroviruses (HEVs) exhibit a variety of clinical manifestations ranging from poliomyelitis and encephalomyelitis to respiratory infections and rashes. Human rhinoviruses (HRVs) are the major causes of the common cold. Human parechoviruses (HPeVs) and Aichi virus (AV) are mostly detected in cases of gastroenteritis, and hepatitis A virus (HAV) causes hepatitis with favourable prognosis. In addition to HEVs and HRVs, a large number of viruses are recognized as respiratory pathogens. The conventional respiratory pathogens include influenza A and B viruses, human respiratory syncytial virus (RSV), adenoviruses (AdVs), parainfluenza viruses (PIVs) and the human coronaviruses (hCoVs) OC43 and 229E. Moreover, several new respiratory pathogens, such as human metapneumovirus (hMPV), severe acute respiratory syndrome coronavirus (SARS-CoV), and the hCoVs HKU1 and NL63 have been found during the 2000s. Human bocavirus (hBoV) is also increasingly being recognized as a true pathogen of humans. Since many clinical illnesses may be caused by several different viruses, multiplex assays for simultaneous detection of several viruses are increasingly being applied. Real-time multiplex polymerase chain reaction (PCR) assays for detection of viral nucleic acids offer remarkable benefits, such as short turnaround time and the non-necessity for handling amplified products. Since multiplexing, utilizing real-time PCR, is limited by reduction in amplification efficiency due to multiple primer and probe sets, separate amplification and hybridization reactions have re-emerged in attempts to develop tests with broad diagnostic range. With this approach microarrays, which have the potential for resolving complex mixtures of amplification products, may be applied. In this study, a multiplex reverse transcription-PCR (RT-PCR) and liquid hybridization assay for sensitive detection of HEV, HRV, HPeV and AV were developed and a single RT-PCR and liquid hybridization assay for detection of HAV was optimized. In analysis of clinical samples, the results obtained by the multiplex assay were consistent with those obtained by routine diagnostic assays. When 68 stool samples were analysed for the presence of HPeV and AV, one sample positive for HPeV was detected. This finding is in line with the current knowledge of neither of these viruses being very common enteric pathogens. More rapid detection of HEV and HRV in respiratory samples was achieved when a real-time duplex RT-PCR assay for detection of these viruses was developed. The same approach was used to develop another assay for more sensitive detection of RSV than with the direct fluorescent assay (DFA) and simultaneous identification of hMPV. Both multiplex real-time RT-PCR assays provided reliable and sensitive detection of their targets, except for detection of HRV, since doubts were raised on the ability of the assay to detect all rhinoviruses. Moreover, two commercial hMPV antibodies were found applicable for detection of the virus in respiratory samples by DFA. Results from analysis of respiratory samples using the duplex real-time RT-PCR assays were compared with those obtained with DFA and the Respiratory Viral Panel (RVP) Fast test, a bead-based suspension microarray test evaluated for routine diagnosis. The RVP Fast assay and PCR showed similar detection rates, except for HEV/HRV, for which a higher detection rate by RVP was observed. All PCR-based assays presented more findings of their target viruses than DFA. The broad detection range of the RVP Fast assay resulted in a nearly threefold overall detection rate, compared with that by DFA. Moreover, analysis of clinical samples resulted in a notable prevalence of hMPV and non-SARS-hCoVs, which emphasizes the role of these viruses as respiratory pathogens. Although the RVP Fast assay demonstrated adequate overall performance, doubts were raised on the ability of the test to detect the H1N1 2009 influenza A virus and all AdV serotypes. Evaluation of the RVP Fast assay demonstrated the remarkable increase in overall viral detection rate that results from adapting a PCR-based multiplex assay to virus diagnostics. The sensitive detection of all the viruses of clinical relevance facilitates efficient infection control measures and appropriate patient management and enables systematic studies on the clinical importance of coinfections. Moreover, collection of data on occurrence of all the viruses of clinical relevance will enable a better understanding of the seasonality, geographical distribution and risk groups of the viral pathogens.
  • Stenvall, Niina (Helsingin yliopisto, 2006)
    The primary aim of the present study was to find an efficient and simple method of vegetative propagation for producing large numbers of hybrid aspen (Populus tremuloides L. x P. tremula Michx.) plants for forest plantations. The key objectives were to investigate the main physiological factors that affect the ability of cuttings to regenerate and to determine whether these factors could be manipulated by different growth conditions. In addition, clonal variation in traits related to propagation success was examined. According to our results, with the stem cutting method, depending on the clone, it is possible to obtain only 1−8 plants from one stock plant per year. With the root cutting method the corresponding values for two-year-old stock plants are 81−207 plants. The difference in number of cuttings between one- and two-year-old stock plants is so pronounced that it is economically feasible to grow stock plants for two years. There is no reason to use much older stock plants as a source of cuttings, as it has been observed that rooting ability diminishes as root diameter increases. Clonal variation is the most important individual factor in propagation of hybrid aspen. The fact that the efficiently sprouted clones also rooted best facilitates the selection of clones for large-scale propagation. In practice, root cuttings taken from all parts of the root system of hybrid aspen were capable of producing new shoots and roots. However, for efficient rooting it is important to use roots smaller than one centimeter in diameter. Both rooting and sprouting, as well as sprouting rate, were increased by high soil temperature; in our studies the highest temperature tested (30ºC) was the best. Light accelerated the sprouting of root cuttings, but they rooted best in dark conditions. Rooting is essential because without roots the sprouted cutting cannot survive long. For aspen the criteria for clone selection are primarily fiber qualities and growth rate, but ability to regenerate efficiently is also essential. For large-scale propagation it is very important to find clones from which many cuttings per stock plant can be obtained. In light of production costs, however, it is even more important that the regeneration ability of the produced cuttings be high.
  • Rasila, Antti (Helsingin yliopisto, 2005)