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  • Leinonen, Maarit (Helsingin yliopisto, 2013)
    A randomised trial on alternative screening methods implemented in the organised cervical cancer screening programme has been running in Finland since 1999. In this trial, screening with an automation assisted cytology and screening with a primary HPV DNA test (the latter since 2003) is compared to screening with a conventional cytology (Pap test). The ultimate aim of the trial is to assess the incidence of cervical precancerous lesions and cancer following the initial screening visit. This setting enables to evaluate the effectiveness of screening using different screening modalities. The aim of this study was to study the prevalence of the carcinogenic cervical HPV infection in Finland and to evaluate the use of an HPV DNA test in cervical cancer screening as a primary screening test. A cytology triage followed for women who were found to be HPV DNA-positive. HPV DNA-positive women were then referred to colposcopy based on the cytology triage result, similarly as in the conventional protocol. Performance and validity of a primary HPV DNA test with cytology triage in comparison with a conventional cytology was evaluated both in a cross-sectional and in a prospective setting. Screening methods were compared by measuring following crosssectional parameters at the initial (index) screening: test positivity, recommendation to intensive screening, referral to colposcopy and histological detection rates. We also estimated relative sensitivity, relative specificity and positive predictive values of the screening methods for different histological outcomes. Effects of screening methods on the burden of precancerous lesions and cancer were studied also in a longitudinal followup design. We analysed hazard ratios between study arms and cumulative hazards of cervical lesion for the different histological outcomes from the prospective data. The majority of the cervical precancerous lesions in Finland are currently detected outside the national programme. Thus, the effectiveness of screening in the Finnish female population cannot be completely evaluated from the cervical lesions detected only within the screening programme. Therefore, we used data from the screening register and appended it by retrieving cervical lesions also from the Finnish Cancer Registry and from the Care Registers for Social Welfare and Health Care (formerly the Finnish Hospital Discharge Register, HDR) maintained by the THL. These registers included also lesions that were detected outside the national screening programme. Our study showed a similar inverse relationship between the prevalence of carcinogenic HPV infection (high-risk HPV, hrHPV) and age reported in other developed countries. Age was found to be a strong determinant of hrHPV infection. Other significant risk factors included marital status and a previous hysterectomy. Prevalence rate of any hrHPV infection reflects the background risk for cervical cancer. It was at the same level, or at least it was not markedly lower than in other European countries. This indicates that the low burden of cervical cancer is due to the health care actions including free public screenings within the organised programme. Type-specific HPV prevalence was somewhat lower than suggested by international meta-analyses. The most common hrHPV type was HPV 16 followed by 31 and 52. The distribution of the hrHPV types in Finland was closest to reports from Eastern Europe suggesting that HPV types found in Finland are consistent with a regional HPV type distribution in the world. HPV 16 attributed one fifth of the referrals to colposcopy but caused clearly more than half of the most severe cervical precancerous lesions and cancers(CIN 3+). At the index screen visit, there were equal numbers of colposcopies in both study arms. However, screening by the HPV DNA test detected significantly more mild and moderate cervical lesions (CIN 1 and CIN 2) in comparison with screening by the cytology. The relative specificity and the positive predictive value (PPV) of the HPV DNA test alone were inferior to cytology. However, the relative specificity of the HPV DNA test with cytology triage was similar and even slightly better than that of cytology among women 35 years and older. The PPVs of the HPV DNA test with cytology triage were consistently better than those of conventional screening. Recommendations to intensive screening were made more often in the HPV than in the conventional arm. This was mainly due to the low age of the screening population (< 35 years). During one screening round of five years, the HPV test identified women at risk for severe cervical precancerous lesion or cancer (CIN 3+) markedly better than cytology. The cumulative detection rates of cervical lesions over one screening round showed that a very few cases of CIN 3 or AIS were diagnosed later than three and a half years after an invitation to an HPV screening arm among women aged 35 years and older. On the contrary, there was a rather constant increase in the detection of CIN 3 or AIS in the conventional screening arm between the years of two and five following the initial screening. This difference between the screening arms suggests an opportunity for earlier diagnosis of high-grade cervical lesions if HPV DNA test would be used used as a routine screening test. After a negative HPV DNA test result (92% of the screened), there were substantially less CIN 3+ cases detected than after a normal result in cytology (93% of the screened) at the index screen visit. This indicates that HPV-based screening better identifies women with whom an extended screening interval would be safe. This could potentially reduce the screening demand for a large group of women and thus result in significant cost savings. In a population-based screening programme, most women are healthy. Also, CIN 3 and cancer are rare outcomes in well-screened populations. This necessitates a careful balance between sensitivity and specificity of the screening tests. On the other hand, when the outcome is rare, there is then less potential for new interventions to improve prevention. Thus, more aggressive protocols might be warranted to increase the effectiveness of screening. An important issue in HPV screening is how to manage HPV-positive women. Intensive surveillance with frequent colposcopies may easily result in overdiagnosis and overtreatment of cervical lesions. This in turn may have economical and psychosocial consequences and result in morbidity for women of reproductive age. When the HPV DNA test is considered as a measure for routine use, then age groups and screening intervals need to be carefully selected. This applies particularly to the algorithm that follows a positive HPV DNA test result. HPV testing should only be done within the organised screening programme whilst a gradual implementation of HPV screening in other regions in Finland would be preferred. This allows for systematical evaluation of possible adverse effects and the effectiveness of screening.
  • Nihtinen, Anne (Helsingin yliopisto, 2012)
    Invasive fungal infections constitute a potentially lethal complication in patients with acute leukaemia and in allogeneic stem cell transplant (SCT) recipients. The poor prognosis is associated with delays in the diagnosis of these infections. Colonization of the mucous membranes is the first step in the pathogenesis of IFI. With Candida infections the colonization occurs in the gastrointestinal tract. Aspergillus spores enter the body from the air to the lungs. Air filtration reduces the number of spores in the air and the risk of invasive aspergillosis (IA). The studies in this thesis had their focus on the prevention and serological diagnostic methods of IA and invasive candidiasis (IC). The following factors were investigated in 102 adult allogeneic SCT recipients transplanted in 2001-2002: nasal colonization with Aspergillus species, oral colonization with Candida species, the feasibility of two antigen tests (Aspergillus galactomannan and Candida mannan) as diagnostic tools, and the incidence of IA and IC. Simultaneously with the patient sampling, environmental samples were obtained from the HEPA-filtered SCT ward to asses the role of environmental exposure to moulds as a risk factor for IA. Nasal samples yielded positive results in three patients. Two patients had IA. Of the 2071 serum samples, 12 (0.6%) yielded positive results with the galactomannan antigen test in nine patients (8.8%). One of these patients had IA. The oral samples yielded positive results in 38 patients but only one patient had IC. In this patient, the Candida mannan test yielded the first positive result seven weeks before the infection. Single false positive test results were common; they were detected in 54 patients. False results were associated with the use of acyclovir and valacyclovir. Aspergillus species were detected in only 6.1% of the environmental samples. The air quality also remained good during a period of heavy construction activity in the immediate vicinity of the SCT ward. Such periods can cause outbreaks of IA. Fluconazole prophylaxis was assessed in 1089 adult patients with acute leukaemia by comparing the incidence of IC in 847 patients not receiving prophylaxis (years 1978-1999) to 242 patients receiving fluconazole prophylaxis (years 2000-2004). The incidence of IC was 8.7% and 1.6% (P less than 0.001). The efficacy of Amphotericin B (AmB) inhalation prophylaxis was analysed in allogeneic SCT recipients. Antifungal prophylaxis was not given to 257 patients transplanted in 1996-2000 (Period I). In the 354 patients transplanted in 2001-2005 (Period II) AmB inhalation prophylaxis was started in cases of acute graft-versus-host disease requiring therapy with high-dose methylprednisolone. IA was detected in 17 (6.6%) vs. 9 (2.5%) of the patients in Period I and Period II (P = 0.007).
  • Lindström, Jaana (Helsingin yliopisto, 2006)
    Type 2 diabetes is an increasing, serious, and costly public health problem. The increase in the prevalence of the disease can mainly be attributed to changing lifestyles leading to physical inactivity, overweight, and obesity. These lifestyle-related risk factors offer also a possibility for preventive interventions. Until recently, proper evidence regarding the prevention of type 2 diabetes has been virtually missing. To be cost-effective, intensive interventions to prevent type 2 diabetes should be directed to people at an increased risk of the disease. The aim of this series of studies was to investigate whether type 2 diabetes can be prevented by lifestyle intervention in high-risk individuals, and to develop a practical method to identify individuals who are at high risk of type 2 diabetes and would benefit from such an intervention. To study the effect of lifestyle intervention on diabetes risk, we recruited 522 volunteer, middle-aged (aged 40 - 64 at baseline), overweight (body mass index > 25 kg/m2) men (n = 172) and women (n = 350) with impaired glucose tolerance to the Diabetes Prevention Study (DPS). The participants were randomly allocated either to the intensive lifestyle intervention group or the control group. The control group received general dietary and exercise advice at baseline, and had annual physician's examination. The participants in the intervention group received, in addition, individualised dietary counselling by a nutritionist. They were also offered circuit-type resistance training sessions and were advised to increase overall physical activity. The intervention goals were to reduce body weight (5% or more reduction from baseline weight), limit dietary fat (< 30% of total energy consumed) and saturated fat (< 10% of total energy consumed), and to increase dietary fibre intake (15 g / 1000 kcal or more) and physical activity (≥ 30 minutes/day). Diabetes status was assessed annually by a repeated 75 g oral glucose tolerance testing. First analysis on end-points was completed after a mean follow-up of 3.2 years, and the intervention phase was terminated after a mean duration of 3.9 years. After that, the study participants continued to visit the study clinics for the annual examinations, for a mean of 3 years. The intervention group showed significantly greater improvement in each intervention goal. After 1 and 3 years, mean weight reductions were 4.5 and 3.5 kg in the intervention group and 1.0 kg and 0.9 kg in the control group. Cardiovascular risk factors improved more in the intervention group. After a mean follow-up of 3.2 years, the risk of diabetes was reduced by 58% in the intervention group compared with the control group. The reduction in the incidence of diabetes was directly associated with achieved lifestyle goals. Furthermore, those who consumed moderate-fat, high-fibre diet achieved the largest weight reduction and, even after adjustment for weight reduction, the lowest diabetes risk during the intervention period. After discontinuation of the counselling, the differences in lifestyle variables between the groups still remained favourable for the intervention group. During the post-intervention follow-up period of 3 years, the risk of diabetes was still 36% lower among the former intervention group participants, compared with the former control group participants. To develop a simple screening tool to identify individuals who are at high risk of type 2 diabetes, follow-up data of two population-based cohorts of 35-64 year old men and women was used. The National FINRISK Study 1987 cohort (model development data) included 4435 subjects, with 182 new drug-treated cases of diabetes identified during ten years, and the FINRISK Study 1992 cohort (model validation data) included 4615 subjects, with 67 new cases of drug-treated diabetes during five years, ascertained using the Social Insurance Institution's Drug register. Baseline age, body mass index, waist circumference, history of antihypertensive drug treatment and high blood glucose, physical activity and daily consumption of fruits, berries or vegetables were selected into the risk score as categorical variables. In the 1987 cohort the optimal cut-off point of the risk score identified 78% of those who got diabetes during the follow-up (= sensitivity of the test) and 77% of those who remained free of diabetes (= specificity of the test). In the 1992 cohort the risk score performed equally well. The final Finnish Diabetes Risk Score (FINDRISC) form includes, in addition to the predictors of the model, a question about family history of diabetes and the age category of over 64 years. When applied to the DPS population, the baseline FINDRISC value was associated with diabetes risk among the control group participants only, indicating that the intensive lifestyle intervention given to the intervention group participants abolished the diabetes risk associated with baseline risk factors. In conclusion, the intensive lifestyle intervention produced long-term beneficial changes in diet, physical activity, body weight, and cardiovascular risk factors, and reduced diabetes risk. Furthermore, the effects of the intervention were sustained after the intervention was discontinued. The FINDRISC proved to be a simple, fast, inexpensive, non-invasive, and reliable tool to identify individuals at high risk of type 2 diabetes. The use of FINDRISC to identify high-risk subjects, followed by lifestyle intervention, provides a feasible scheme in preventing type 2 diabetes, which could be implemented in the primary health care system.
  • Khami, Mohammad Reza (Helsingin yliopisto, 2007)
    The present study investigated the preventive orientation of the dental education system in Iran as reflected in the responses of dental school educators and dental students to a questionnaire survey. Two questionnaires, one for dental school educators and one for senior dental students, were designed and piloted. Of the 15 state dental schools in Iran, 7 were selected using a multi-stage sampling approach, and all the dental school educators and senior dental students in these schools were asked to voluntarily fill in the anonymous questionnaires. Totally, 291 educators (80%) and 270 students (82%) participated in the study. In addition to background information, both questionnaires requested information on knowledge of caries prevention, attitudes towards preventive dentistry and oral health behaviour of the respondents. The students' questionnaire also covered items concerning prevention-oriented practice, study motives, and career preferences. Contrary to knowledge and attitudes of the students, those of the educators' were positively associated with some of their academic and personal background characteristics. Women were more likely to report favourable oral self-care habits than men. The other determinants of oral health behaviour were educators' familiarity with the oral public health field, and students' attitudes towards prevention. A higher score on preventive practice among the students was associated with better oral self-care habits and positive attitudes towards prevention. Characteristics of the profession and social status and security were the top-ranked that motivated students to study dentistry, and students mainly preferred to enter postgraduate courses and private practice after graduation. To increase the orientation of Iran's health care system towards prevention, and to cope with current concepts of prevention, corresponding changes should be made in the dental education system. The results of this study support the revision of the dental curriculum by placing more emphasis on prevention-related topics and by integrating prevention-related concepts into all disciplines. Additionally, practicing dentists and dental educators should be provided with opportunities to attend continuing education courses and to conduct seminars and congresses on various aspects of preventive dentistry at home as well as abroad.
  • Tseveenjav, Battsetseg (Helsingin yliopisto, 2004)
  • Ghasemi, Hadi (Helsingin yliopisto, 2008)
    The present study investigated the preventive orientation of Iranian dentists and what they perceived as barriers to the provision of preventive dental care. The target population comprised Iranian general dental practitioners that took part in two major dental congresses in Tehran, Iran, one in December 2004, and the other in July 2005. Data was gathered by means of a self-administered questionnaire which was filled in anonymously. The questionnaire covered dentists' knowledge of caries prevention, attitudes towards preventive dental care, self-assessed oral health behaviour, restorative treatment threshold, risk-based preventive practice, involvement in smoking cessation, perceived barriers for carrying out preventive dental care, practice-related information, activity in continuing education and background information. In total, 1033 dentists completed the questionnaire, and 980 were eligible for the present study; their mean age was 37.3 years, and 64% were men. The dentists showed high levels of knowledge of and positive attitudes towards preventive dental care. They, however, underestimated the role of fluoride toothpaste. More than half the dentists complied with the optimal level of oral self-care and almost half reported having visited a dentist for a routine dental check-up during the last year. There was a strong tendency among the dentists to intervene in proximal enamel caries restoratively. The majority of the dentists agreed with applying well-known preventive measures, and more than half reported that they always recommend that a smoking patient quit the habit. Dentists’ level of preventive input was positively correlated with their knowledge of and attitudes towards preventive dental care. Moreover, this correlation was evident regarding the dentists’ activities for their own oral health. Patient-related factors were the most frequently cited barrier among these dentists for the provision of preventive dental care. Generally, female dentists demonstrated a stronger preventive orientation than did male dentists. It can be concluded that there is room for improvement in dentists' knowledge of and attitudes towards preventive dental care, and this requires placing more emphasis on relevant areas in dental education. More understanding of barriers to the provision of preventive dental care is required to facilitate dentists' preventive practice.
  • Ikonen, Annukka (Helsingin yliopisto, 2012)
    ABSTRACT In Finland, most employers offer primary care for their employees in addition to the preventive occupational health services (OHS). The purpose of this study was to determine the role of OHS in the health care of working persons as well as the relationship between primary care visits to OHS and prevention and work-related factors. The study showed that over 50% of employees used only OHS for primary care and the use of public health care was reduced. Men seemed to favour OHS as a primary health care provider. The proportion of visits to occupational health (OH) physicians was found to have increased compared to other OH professionals. Mental health problems, musculoskeletal disorders, chronic illnesses impairing work ability, and poor work ability were associated with visits to OHS but still about half of the employees with these problems did not use OHS. The role of OH nurses seemed important in detecting insomnia, burnout, and depressive disorders. Work-related symptoms and work ability were found to be frequently examined during OHS primary care visits. Over half of the visits to OH physicians were work-related when the reason for consulting was at least partially due to work or when the need for sickness absence was considered. Workplace harassment and lack of influence on one s work was associated with visits to OH nurses or physicians, indicating that they have the possibility to gain knowledge about work-related factors through primary care visits. Employers requirements of sickness certificates covering the first day of sickness were associated with visiting OHS among men. The role of supervisors in controlling short sickness absences could be emphasized. Although health promotion and interventions aimed at work were carried out in primary care visits to OH physicians, interventions aimed at workplaces could be increased. In conclusion, OHS primary care contributes to preventive activities and is often interrelated with employees work and work ability.
  • Riska, Annika (Helsingin yliopisto, 2007)
    The aim of the study was to clarify the occurrence, and etiological and prognostic factors of primary fallopian tube carcinoma (PFTC). We studied the sociodemographic determinants of the incidence of PFTC in Finland and the role of chlamydial infections and human papillomavirus infections as risk factors for PFTC. Serum tumor markers were studied as prognostic factors for PFTC. We also evaluated selected reproductive factors (parity, sterilization and hysterectomy) as risk or protective factors of PFTC. The risks of second primary cancers after PFTC were also studied. The age-adjusted incidence of PFTC in Finland increased to 5.4 / 1,000,000 in 1993 97. The incidence rate was higher in the cities, but the relative rise was higher in rural areas. Women in the two highest social classes showed a 1.8 fold incidence compared with those in the lowest. Women in agriculture and those not working outside the home showed only half the PFTC incidence of those in higher socioeconomic occupations. Pretreatment serum concentrations of hCGβ, CA125 and TATI were evaluated as prognostic markers for PFTC. Elevated hCGβ values (above the 75th percentile, 3.5 pmol/L; OR 2.49, 95% CI 1.22 5.09), stage and histology were strong independent prognostic factors for PFTC. The effects of parity, sterilization and hysterectomy on the risk of PFTC were studied in a case control-study with 573 PFTC cases from the Finnish Cancer Registry. In multivariate analysis parity was the only significant protective factor as regards PFTC, with increasing protection associated with increasing number of deliveries. In univariate analysis sterilization gave borderline protection against PFTC and the protective effect increased with time since the operation. In multivariate analysis the protection did not reach statistical significance. Chlamydial and human papillomavirus (HPV) infections were studied in two separate seroepidemiological case-control studies with 78 PFTC patients. The incidence of women with positive HPV or chlamydial serology was the same in PFTC patients and in the control group and was not found to be a risk factor for PFTC. Finally, the possible risk of a second primary cancer after diagnosis and treatment of PFTC in a cohort of 2084 cases from 13 cancer registries followed for second primary cancers within the period 1943 2000 was studied. In PFTC patients, second primary cancers were 36% more common than expected (SIR 1.36, 95% CI 1.13 1.63). In conclusion, the incidence of PFTC has increased in Finland, especially in higher social classes and among those in certain occupations. Elevated serum hCGβ reflect a worsened prognosis. Parity is a clear protective factor, as is previous sterilization. After PFTC there is a risk of second primary cancers, especially colorectal, breast, lung and bladder cancers and non-lymphoid leukemia. The excess of colorectal and breast cancers after PFTC may indicate common effects of earlier treatments, or they could reflect common effects of lifestyle or genetic, immunological or environmental background.
  • Mäkelä, Keijo (Helsingin yliopisto, 2010)
    The first aim of the current study was to evaluate the survival of total hip arthroplasty (THA) in patients aged 55 years and older on a nation-wide level. The second aim was to evaluate, on a nation wide-basis, the geographical variation of the incidence of primary THA for primary OA and also to identify those variables that are possibly associated with this variation. The third aim was to evaluate the effects of hospital volume: on the length of stay, on the numbers of re-admissions and on the numbers of complications of THR on population-based level in Finland. The survival of implants was analysed based on data from the Finnish Arthroplasty Register. The incidence and hospital volume data were obtained from the Hospital Discharge Register. Cementless total hip replacements had a significantly reduced risk of revision for aseptic loosening compared with cemented hip replacements. When revision for any reason was the end point in the survival analyses, there were no significant differences found between the groups. Adjusted incidence ratios of THA varied from 1.9- to 3.0-fold during the study period. Neither the average income within a region nor the morbidity index was associated with the incidence of THA. For the four categories of volume of total hip replacements performed per hospital, the length of the surgical treatment period was shorter for the highest volume group than for the lowest volume group. The odds ratio for dislocations was significantly lower in the high volume group than in the low volume group. In patients who were 55 years of age or older, the survival of cementless total hip replacements was as good as that of the cemented replacements. However, multiple wear-related revisions of the cementless cups indicate that excessive polyethylene wear was a major clinical problem with modular cementless cups. The variation in the long-term rates of survival for different cemented stems was considerable. Cementless proximal porous-coated stems were found to be a good option for elderly patients. When hip surgery was performed on with a large repertoire, the indications to perform THAs due to primary OA were tight. Socio-economic status of the patient had no apparent effect on THA rate. Specialization of hip replacements in high volume hospitals should reduce costs by significantly shortening the length of stay, and may reduce the dislocation rate.
  • Ahti, Nikunlassi (Helsingin yliopisto, 2008)
    Relative Constructions with Pronominal Heads in Contemporary Russian Chapter 1 introduces the distinctive syntactic and semantic properties of Russian relative constructions (RCs), which are then divided into two main classes according to the type of the head phrase. The study concentrates on RCs with pronominal heads, which are systematically compared with noun-headed RCs. Chapter 2 clarifies the categorization of pronouns in Russian. The conclusion is that Russian pronouns include only personal, reflexive and wh-pronouns. The remaining words that are traditionally seen as pronouns are actually functional equivalents of determiners. This idea leads to the suggestion that RCs with these determiner-like words as the only constituent of the head phrase are actually headed by zero pronouns. In the other type of RCs with pronominal heads, the head position is occupied by wh-pronouns with clitics expressing different types of indefiniteness and quantification. Comparison of the two types of pronoun-headed RCs shows that the wh-heads and zero-heads share a number of common properties with respect to the grammatical gender, number and person as well as to the semantic distinction between animates and inanimates. The rest of Chapter 2 gives an overview of various uses of wh-pronouns in Russian and an experimental analysis of RCs headed by pronominal adverbs. Chapter 3 discusses fundamental differences between RCs with noun and pronominal heads. One of the main findings is that the choice of the relative pronoun (kto 'who' and chto 'what' versus kotoryj 'which') is motivated by a tendency to reproduce maximally the essential grammatical and semantic properties of the antecedent. Chapter 4 gives a detailed description of the determiner-like words and wh-based heads used in the two types of RCs with pronominal heads. In addition, several issues related to the syntax and semantics of free relatives are discussed. The conclusion is that there is no need to establish a separate category of free relatives in Russian. Chapter 5 discusses the syntax and semantics of correlative and free concessive constructions. They share a number of properties with pronoun-headed RCs and the two are often confused in Russian linguistics. However, a detailed analysis shows that these constructions must be distinguished from RCs. The study combines the methods of functionally-oriented Russian structuralism with some insights from generative syntax.
  • Muhonen, Vesa (Helsingin yliopisto, 2008)
    The increased accuracy in the cosmological observations, especially in the measurements of the comic microwave background, allow us to study the primordial perturbations in grater detail. In this thesis, we allow the possibility for a correlated isocurvature perturbations alongside the usual adiabatic perturbations. Thus far the simplest six parameter \Lambda CDM model has been able to accommodate all the observational data rather well. However, we find that the 3-year WMAP data and the 2006 Boomerang data favour a nonzero nonadiabatic contribution to the CMB angular power sprctrum. This is primordial isocurvature perturbation that is positively correlated with the primordial curvature perturbation. Compared with the adiabatic \Lambda CMD model we have four additional parameters describing the increased complexity if the primordial perturbations. Our best-fit model has a 4% nonadiabatic contribution to the CMB temperature variance and the fit is improved by \Delta\chi^2 = 9.7. We can attribute this preference for isocurvature to a feature in the peak structure of the angular power spectrum, namely, the widths of the second and third acoustic peak. Along the way, we have improved our analysis methods by identifying some issues with the parametrisation of the primordial perturbation spectra and suggesting ways to handle these. Due to the improvements, the convergence of our Markov chains is improved. The change of parametrisation has an effect on the MCMC analysis because of the change in priors. We have checked our results against this and find only marginal differences between our parametrisation.
  • Taanila, Olli (Helsingin yliopisto, 2010)
    Inflation is a period of accelerated expansion in the very early universe, which has the appealing aspect that it can create primordial perturbations via quantum fluctuations. These primordial perturbations have been observed in the cosmic microwave background, and these perturbations also function as the seeds of all large-scale structure in the universe. Curvaton models are simple modifications of the standard inflationary paradigm, where inflation is driven by the energy density of the inflaton, but another field, the curvaton, is responsible for producing the primordial perturbations. The curvaton decays after inflation as ended, where the isocurvature perturbations of the curvaton are converted into adiabatic perturbations. Since the curvaton must decay, it must have some interactions. Additionally realistic curvaton models typically have some self-interactions. In this work we consider self-interacting curvaton models, where the self-interaction is a monomial in the potential, suppressed by the Planck scale, and thus the self-interaction is very weak. Nevertheless, since the self-interaction makes the equations of motion non-linear, it can modify the behaviour of the model very drastically. The most intriguing aspect of this behaviour is that the final properties of the perturbations become highly dependent on the initial values. Departures of Gaussian distribution are important observables of the primordial perturbations. Due to the non-linearity of the self-interacting curvaton model and its sensitivity to initial conditions, it can produce significant non-Gaussianity of the primordial perturbations. In this work we investigate the non-Gaussianity produced by the self-interacting curvaton, and demonstrate that the non-Gaussianity parameters do not obey the analytically derived approximate relations often cited in the literature. Furthermore we also consider a self-interacting curvaton with a mass in the TeV-scale. Motivated by realistic particle physics models such as the Minimally Supersymmetric Standard Model, we demonstrate that a curvaton model within the mass range can be responsible for the observed perturbations if it can decay late enough.
  • Honti, Rita (Helsingin yliopisto, 2006)
    The topic of my doctoral thesis is to demonstrate the usefulness of incorporating tonal and modal elements into a pitch-web square analysis of Béla Bartók's (1881-1945) opera, 'A kékszakállú herceg vára' ('Duke Bluebeard's Castle'). My specific goal is to demonstrate that different musical materials, which exist as foreground melodies or long-term key progressions, are unified by the unordered pitch set {0,1,4}, which becomes prominent in different sections of Bartók's opera. In Bluebeard's Castle, the set {0,1,4} is also found as a subset of several tetrachords: {0,1,4,7}, {0,1,4,8}, and {0,3,4,7}. My claim is that {0,1,4} serves to link music materials between themes, between sections, and also between scenes. This study develops an analytical method, drawn from various theoretical perspectives, for conceiving superposed diatonic spaces within a hybrid pitch-space comprised of diatonic and chromatic features. The integrity of diatonic melodic lines is retained, which allows for a non-reductive understanding of diatonic superposition, without appealing to pitch centers or specifying complete diatonic collections. Through combining various theoretical insights of the Hungarian scholar Ernő Lendvai, and the American theorists Elliott Antokoletz, Paul Wilson and Allen Forte, as well as the composer himself, this study gives a detailed analysis of the opera's pitch material in a way that combines, complements, and expands upon the studies of those scholars. The analyzed pitch sets are represented on Aarre Joutsenvirta's note-web square, which adds a new aspect to the field of Bartók analysis. Keywords: Bartók, Duke Bluebeard's Castle (Op. 11), Ernő Lendvai, axis system, Elliott Antokoletz, intervallic cycles, intervallic cells, Allen Forte, set theory, interval classes, interval vectors, Aarre Joutsenvirta, pitch-web square, pitch-web analysis.
  • Kopotev, Mikhail (Helsingin yliopisto, 2009)
    The PhD thesis consists of an Introduction and four articles published both in Finland and abroad, written in English or Russian. They present the case studies of eight Finnish and Russian idiomatic constructions, alternatively called formal idioms (Ch. Fillmore, P. Kay, etc.) or syntactic phrasemes (I. Melčuk). Items under consideration in the book appear in the following examples: Ikkuna rikki — Окно сломано, lit.: ‘the window broken’, Äiti täällä — Мама здесь, lit.: ‘mother here’, Kaikki myymälöihin! — Все в магазин, lit.: ‘all to the shops’, Пить так пить! ≈ ‘When I drink, I drink (a lot)!’, etc. The aim of the studies is to reconstruct the origins and to trace the development of the above-mentioned constructions up to their modern usages. To this end, the constructions are investigated both from diachronic and from typological perspectives. Finally, the case studies provide a possibility to develop more general bases of syntactic idiomatization. By attempting to answer the question why the idiomatic constructions develop even though they destroy the harmonious structure of а language, some principles of idiomatization are postulated in the Conclusion.
  • Hyvärinen, Kati (Helsingin yliopisto, 2013)
    Atherosclerotic vascular diseases (ASVDs) affect the heart and circulatory system. One of the most common forms is coronary artery disease (CAD) which may eventually lead to acute coronary syndrome (ACS). ASVDs are currently the leading cause of mortality worldwide, and account for 47% of all deaths in Europe. The underlying mechanism is atherosclerosis, a progressive disease that manifests in several tissues. Common chronic infections, including periodontal disease and Chlamydia pneumoniae, may promote atherosclerosis and are associated with an increased risk of ASVDs. The general aims of this thesis project were to investigate the role of bacteria associated with periodontal disease in CAD, and the mechanisms by which common chronic infections promote proatherogenic alterations. More specifically, we aimed to: I) study the effects of Aggregatibacter actinomycetemcomitans and C. pneumoniae infections on the liver and adipose tissue lipid homeostasis and inflammation status in mice; II) develop and validate a quantitative PCR (QPCR) method to analyze the levels of periodontal disease-associated bacteria in saliva; and III) determine the association between salivary pathogen levels and CAD. The animal studies were conducted in atherosclerosis-susceptible apolipoprotein E-deficient mice. They were infected intravenously with viable A. actinomycetemcomitans and intranasally with viable C. pneumoniae. Consequently, the pathogens were recovered in the liver and C. pneumonia also in the lungs. Both infections induced systemic and hepatic inflammation, which were seen as an elevation of inflammation markers. Chronic C. pneumoniae infection induced hepatic microvesicular formations, which may promote steatosis. The recurrent A. actinomycetemcomitans infection disturbed the lipid homeostasis of adipose tissue: the proportion of saturated fatty acids was increased and that of polyunsaturated fatty acid decreased. The alterations in adipose tissue transcriptomes were depot-specific, and the inguinal adipose tissue was especially prone to inflammation-related responses. Single-copy gene-based QPCR assays were developed for five periodontal disease-associated bacteria: A. actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythia. The assays were validated in a case-control population including periodontally diseased and healthy subjects, and the diagnostic ability was found to be potent. The association of these pathogens with CAD was determined by analyzing saliva samples from the Parogene cohort (n = 492), consisting of patients with stable CAD, ACS, and no significant CAD as the reference group. All CAD diagnoses were verified by coronary angiography. The increased salivary levels of A. actinomycetemcomitans strongly associated with both stable CAD and ACS. Systemic exposure to the pathogen was seen as elevated serum antibody levels against the pathogen. The findings from the animal study indicate that A. actinomycetemcomitans and C. pneumoniae infections induce inflammation and disturbances in lipid and fatty acid homeostasis in the liver and adipose tissue. The potential tissue dysfunction may further augment the progression of atherosclerosis. The results from the Parogene study demonstrate that high salivary levels and systemic exposure to A. actinomycetemcomitans are associated with the risk of CAD and its acute manifestation. The findings from the thesis study are of common interest, because the studied pathogens are highly prevalent among the general population and their persistence may increase the overall risk of ASVDs.
  • Wettig, Hannes (Helsingin yliopisto, 2013)
    This thesis starts out by reviewing Bayesian reasoning and Bayesian network models. We present results related to discriminative learning of Bayesian network parameters. Along the way, we explicitly identify a number of problems arising in Bayesian model class selection. This leads us to information theory and, more speci cally, the minimum description length (MDL) principle. We look at its theoretic foundations and practical implications. The MDL approach provides elegant solutions for the problem of model class selection and enables us to objectively compare any set of models, regardless of their parametric structure. Finally, we apply these methods to problems arising in computational etymology. We develop model families for the task of sound-by-sound alignment across kindred languages. Fed with linguistic data in the form of cognate sets, our methods provide information about the correspondence of sounds, as well as the history and ancestral structure of a language family. As a running example we take the family of Uralic languages.
  • Koivusalo, Mirkka (Helsingin yliopisto, 2004)