Dental health and school-based health education among 15-year-olds in Tehran, Iran

The aim of the present study was to assess dental health and its determinants among 15-year-olds in Tehran, Iran and to evaluate the impact of a school-based educational intervention on their oral cleanliness and gingival health. The total sample comprised 506 students. Data collection was performed through a clinical dental examination and a self-administered structured questionnaire. This questionnaire covered the student s background information, socio-economic status, self-perceived dental health, tooth-brushing, and smoking. The clinical dental examination covered caries experience, gingival status, dental plaque status, and orthodontic treatment needs. Participation was voluntary, and all students responded to the questionnaire. Only three students refused the clinical dental examination. The intervention was based on exposing students to dental health education through a leaflet and a videotape designed for the present study. The outcome examinations took place 12 weeks after the baseline among the three groups of the intervention trial (leaflet, videotape, and control). High participation rates at the baseline and scanty drop-outs (7%) in the intervention speak for reliability of the results. Mean value of the DMFT (D=decayed, M=missing, and F=filled teeth) index of the 15-year-olds was 2.1, which comprised DT=0.9, MT=0.2, and FT=1.0 with no gender differences. Dental plaque existed on at least one index tooth of all students, and healthy periodontium (Community Periodontal Index=0) was found in less than 10% of students. Need for caries treatment existed in 40% of students, for scaling in 24%, for oral hygiene instructions in all, and for orthodontic treatment in 26%. Students with the highest level of parents education had fewer dental caries (36% vs. 48%) and less dental plaque (77% vs. 88%). Of all students, 78% assessed their dental health as good or better. Even more of those with their DMFT=0 (73% vs. 27%) and DT=0 (68% vs. 32%) assessed their dental health as good or better. Smokers comprised 5% of the boys and 2% of the girls. Smoking was common among students of less-educated parents (6% vs. 3%). Of all students, 26% reported twice-daily tooth-brushing; girls (38% vs. 15%) and those of higher socio-economic background (33% vs. 17%) did so more frequently. The best predictors for a good level of oral cleanliness were female gender or twice-daily tooth-brushing. The present study demonstrated that a school-based educational intervention can be effective in the short term in improving the oral cleanliness and gingival health of adolescents. At least 50% reduction in numbers of teeth with dental plaque compared to baseline was achieved by 58% of the students in the leaflet group, by 37% in the videotape group, and by 10% of the controls. Corresponding figures for gingival bleeding were 72%, 64%, and 30%. For improving the oral cleanliness and gingival health of adolescents in countries such as Iran with a developing oral health system, school-based educational intervention should be established with focus on oral self-care and oral health education messages. Emphasizing the immediate gains from good oral hygiene, such as fresh breath, clean teeth, and attractive appearance should be key aspects for motivating these adolescents to learn and maintain good dental health, whilst in planning school-based dental health intervention, special attention should be given to boys and those with lower socio-economic status. Author s address: Reza Yazdani, Department of Oral Public Health, Institute of Dentistry, University of Helsinki, P.O. Box 41, FI-00014 Helsinki, Finland. E-mail: reza.yazdani@helsinki.fi

Oral Health among Iranian Preadolescents : A School-Based Health Education Intervention

The present study assessed oral health and its determinants among Iranian preadolescents, and evaluated a school-based health education programme aimed to promote their oral health. The target population of this study comprised a random sample of the third-grade school children (n = 459) of all public primary schools in 19 areas of Tehran city. The data came from a clinical examination of the children and two self-administered questionnaires: one for children, and one for mothers. The clinical dental examination was performed for recording children's oral health. The mothers' questionnaires covered background factors, oral self-care (OSC) behaviours and oral health-related knowledge and attitude statements. After baseline data collection, a community trial was designed as a 3-month school-based intervention study. For the intervention trial, the third-grade classes as the clusters were randomly assigned to the intervention and control groups. Three kinds of intervention were implemented, one in class, one via the parents, and one as a combination of these. One group served as controls with no intervention. The outcome measures of the study were changes in plaque and bleeding scores recorded. The results showed that mean dmft was 3.75 (SD = 2.8) for the primary teeth and mean DMFT was 0.4 (SD = 0.9) for the permanent teeth. All children had plaque on at least one index tooth and bleeding on probing in at least one index tooth occurred in 81%. About one-third (34%) of the children reported favourable OSC and less than half (46%) of the children reported brushing their teeth at least twice daily. Girls reported favourable OSC (OR = 2.0), had decay-free teeth (OR = 1.8) and treated permanent teeth (OR = 3.3) more than did boys. Mother's oral health-related aspects, i.e., mother's favourable OSC, high knowledge levels of and positive attitudes towards oral health, and active supervision of the child's tooth brushing had a positive effect on all aspects of children's oral health status and behaviours (ORs from 1.3 to 1.9). After the intervention, the results showed a strong intervention effect on healthy gingiva in both groups where parents were involved: the parental-aid group (OR = 7.7, 95% CI 2.2-27.7) and combined group (OR = 6.6, 95% CI 2.0-22.1). To improve children's oral health, community school-based oral health educational programmes should be established to include all primary schools. These programmes should benefit from the common risk factor approach and a multi-sectored approach to employ for communication between the community, the school, and the family. Oral health interventions should empower the parents' ability to improve their own oral health behaviour and then to transfer that healthy behaviour to their children.

Oral Health among Young Adults and the Middle-aged in Iran

The aim of the present study was to assess oral health and treatment needs among adult Iranians according to socio-demographic status, smoking, and oral hygiene, and to investigate the relationships between these determinants and oral health. Data for 4448 young adult (aged 18) and 8301 middle-aged (aged 35 to 44) Iranians were collected in 2002 as part of a national survey using the World Health Organization (WHO) criteria for sampling and clinical diagnoses, across 28 provinces by 33 calibrated examiners. Gender, age, place of residence, and level of education served as socio-demographic information, smoking as behavioural and modified plaque index (PI) as the biological risk indicator for oral hygiene. Number of teeth, decayed teeth (DT), filled teeth (FT), decayed, missing, filled teeth (DMFT), community periodontal index (CPI), and prosthodontic rehabilitation served as outcome variables of oral health. Mean number of DMFT was 4.3 (Standard deviation (SD) = 3.7) in young adults and 11.0 (SD = 6.4) among middle-aged individuals. Among young adults the D-component (DT = 70%), and among middle-aged individuals the M-component (60%) dominated in the DMFT index. Among young adults, visible plaque was found in nearly all subjects. Maximum (max) PI was associated with higher mean number of DT, and higher periodontal treatment needs. A healthy periodontium was a rare condition, with 8% of young adults and 1% of middle-aged individuals having a max CPI = 0. The majority of the CPI findings among young adults consisted of calculus (48%) and deepened periodontal pockets (21%). Respective values for middle-aged individuals were 40% and 53%. Having a deep pocket (max CPI = 4) was more likely among young adults with a low level of education (Odds ratio (OR) = 2.7, 95% Confidence interval (CI) = 1.9–4.0) than it was among well-educated individuals. Among middle-aged individuals, having calculus or a periodontal pocket was more likely in men (OR = 1.8, 95% CI = 1.6–2.0) and in illiterate subjects (OR = 6.3, 95% CI = 5.1–7.8) than it was for their counterparts. Among young adults, having 28 teeth was more (p < 0.05) prevalent among men (72% vs. 68% for women), urban residents (71% vs. 67% for rural residents), and those with a high level of education (73% vs. 60% for those with a low level). Among middle-aged individuals, having a functional dentition was associated with younger age (OR = 2.0, 95% CI = 1.7−2.5) and higher level of education (OR = 1.8, 95% CI = 1.6−2.1). Of middle-aged individuals, 2% of 35- to 39-year-olds and 5% of those aged 40 to 44 were edentulous. Among the dentate subjects (n = 7,925), prosthodontic rehabilitation was more prevalent (p < 0.001) among women, urban residents, and those with a high level of education than it was among their counterparts. Among those having 1 to 19 teeth, a removable denture was the most common type of prosthodontic rehabilitation. Middle-aged individuals lacking a functional dentition were more likely (OR = 6.0, 95% CI = 4.8−7.6) to have prosthodontic rehabilitation than were those having a functional dentition. In total, 81% of all reported being non-smokers, and 32% of men and 5% of women were current smokers. Heavy smokers were the most likely to have deepened periodontal pockets (max CPI ≥ 3, OR = 2.9, 95% CI = 1.8−4.7) and to have less than 20 teeth (OR = 2.3, 95% CI = 1.5−3.6). The findings indicate impaired oral health status in adult Iranians, particularly those of low socio-economic status and educational level. The high prevalence of dental plaque and calculus and considerable unmet treatment needs call for a preventive population strategy with special emphasis on the improvement of oral self-care and smoking cessation to tackle the underlying risk factors for oral diseases in the Iranian adult population.

Unraveling the helix of change : An activity-theoretical study of health care change efforts and their consequences

M.A. (Educ.) Anu Kajamaa from the University of Helsinki, Center for Research on Activity, Development and Learning (CRADLE), examines change efforts and their consequences in health care in the public sector. The aim of her academic dissertation is, by providing a new conceptual framework, to widen our understanding of organizational change efforts and their consequences and managerial challenges. Despite the multiple change efforts, the results of health care development projects have not been very promising, and many developmental needs and managerial challenges exist. The study challenges the predominant, well-framed health care change paradigm and calls for an expanded view to explore the underlying issues and multiplicities of change efforts and their consequences. The study asks what kind of expanded conceptual framework is needed to better understand organizational change as transcending currently dominant oppositions in management thinking, specifically in the field of health care. The study includes five explorative case studies of health care change efforts and their consequences in Finland. Theory and practice are tightly interconnected in the study. The methodology of the study integrates the ethnography of organizational change, a narrative approach and cultural-historical activity theory. From the stance of activity theory, historicity, contradictions, locality and employee participation play significant roles in developing health care. The empirical data of the study has mainly been collected in two projects, funded by the Finnish Work Environment Fund. The data was collected in public sector health care organizations during the years 2004-2010. By exploring the oppositions between distinct views on organizational change and the multi-site, multi-level and multi-logic of organizational change, the study develops an expanded, multidimensional activity-theoretical framework on organizational change and management thinking. The findings of the study contribute to activity theory and organization studies, and provide information for health care management and practitioners. The study illuminates that continuous development efforts bridged to one another and anchored to collectively created new activity models can lead to significant improvements and organizational learning in health care. The study presents such expansive learning processes. The ways of conducting change efforts in organizations play a critical role in the creation of collective new practices and tools and in establishing ownership over them. Some of the studied change efforts were discontinuous or encapsulated, not benefiting the larger whole. The study shows that the stagnation and unexpected consequences of change efforts relate to the unconnectedness of the different organizational sites, levels and logics. If not dealt with, the unintended consequences such as obstacles, breaks and conflicts may stem promising change and learning processes.

Teacher Education, School Effectiveness and Improvement : A Study of Academic and Professional Qualification on Teachers' Job Effectiveness in Nigerian Secondary Schools

This academic work begins with a compact presentation of the general background to the study, which also includes an autobiography for the interest in this research. The presentation provides readers who know little of the topic of this research and of the structure of the educational system as well as of the value given to education in Nigeria. It further concentrates on the dynamic interplay of the effect of academic and professional qualification and teachers' job effectiveness in secondary schools in Nigeria in particular, and in Africa in general. The aim of this study is to produce a systematic analysis and rich theoretical and empirical description of teachers' teaching competencies. The theoretical part comprises a comprehensive literature review that focuses on research conducted in the areas of academic and professional qualification and teachers' job effectiveness, teaching competencies, and the role of teacher education with particular emphasis on school effectiveness and improvement. This research benefits greatly from the functionalist conception of education, which is built upon two emphases: the application of the scientific method to the objective social world, and the use of an analogy between the individual 'organism' and 'society'. To this end, it offers us an opportunity to define terms systematically and to view problems as always being interrelated with other components of society. The empirical part involves describing and interpreting what educational objectives can be achieved with the help of teachers' teaching competencies in close connection to educational planning, teacher training and development, and achieving them without waste. The data used in this study were collected between 2002 and 2003 from teachers, principals, supervisors of education from the Ministry of Education and Post Primary Schools Board in the Rivers State of Nigeria (N=300). The data were collected from interviews, documents, observation, and questionnaires and were analyzed using both qualitative and quantitative methods to strengthen the validity of the findings. The data collected were analyzed to answer the specific research questions and hypotheses posited in this study. The data analysis involved the use of multiple statistical procedures: Percentages Mean Point Value, T-test of Significance, One-Way Analysis of Variance (ANOVA), and Cross Tabulation. The results obtained from the data analysis show that teachers require professional knowledge and professional teaching skills, as well as a broad base of general knowledge (e.g., morality, service, cultural capital, institutional survey). Above all, in order to carry out instructional processes effectively, teachers should be both academically and professionally trained. This study revealed that teachers are not however expected to have an extraordinary memory, but rather looked upon as persons capable of thinking in the right direction. This study may provide a solution to the problem of teacher education and school effectiveness in Nigeria. For this reason, I offer this treatise to anyone seriously committed in improving schools in developing countries in general and in Nigeria in particular to improve the lives of all its citizens. In particular, I write this to encourage educational planners, education policy makers, curriculum developers, principals, teachers, and students of education interested in empirical information and methods to conceptualize the issue this study has raised and to provide them with useful suggestions to help them improve secondary schooling in Nigeria. Though, multiple audiences exist for any text. For this reason, I trust that the academic community will find this piece of work a useful addition to the existing literature on school effectiveness and school improvement. Through integrating concepts from a number of disciplines, I aim to describe as holistic a representation as space could allow of the components of school effectiveness and quality improvement. A new perspective on teachers' professional competencies, which not only take into consideration the unique characteristics of the variables used in this study, but also recommend their environmental and cultural derivation. In addition, researchers should focus their attention on the ways in which both professional and non-professional teachers construct and apply their methodological competencies, such as their grouping procedures and behaviors to the schooling of students. Keywords: Professional Training, Academic Training, Professionally Qualified, Academically Qualified, Professional Qualification, Academic Qualification, Job Effectiveness, Job Efficiency, Educational Planning, Teacher Training and Development, Nigeria.

Of tolerance in mice and men : studies in APECED and Aire

Autoimmune diseases affect 5 % of the population and come in many forms, such as diabetes, rheumatoid arthritis and MS. However, how and why autoimmune diseases arise are not yet fully resolved. In this thesis, the onset of autoimmunity was investigated using both patient samples and a mouse model of autoimmunity. Autoimmune diseases are usually complex, due to a number of different causative genes and environmental factors. However, a few monogenic autoimmune diseases have been described, which are caused by mutations in only one gene per disease. One of such disease is called APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy) and is enriched in the Finnish population. The causative gene behind APECED is named AIRE from AutoImmune REgulator. How malfunction of just one gene product can cause the multitude of disease components found in APECED is not yet resolved. This thesis sought out to find out more about the functions of AIRE, in order to reveal why APECED and other autoimmune diseases arise and what goes wrong? Usually, immune cells are taught to distinguish between self and non-self during their development. That way, immune cells can fight off bacteria and microbes while leaving the tissues and organs of the host organism itself unharmed. In APECED, the development of immune cells called αβ T cells is incomplete. The cells are not able to fully distinguish between self and non-self. This leads to autodestruction of self tissues and autoimmune disease. One of the achievements of this thesis was the finding that the development of another set of T cells called γδ T cells is not affected by AIRE in mice or in men. Instead, we found that another type of immune cell important in tolerance, called the dendritic cell is defective in APECED patients and is not able to respond to microbial stimulus in a normal fashion. Finally, we studied Aire-deficient mice and found that autoantibodies expressed in the mice were not targeted against the same molecules as those found in APECED patients. This indicates differences in the autoimmune pathology in mice and men. More work is still required before we understand the mechanisms of tolerance and autoimmunity well enough to be able to cure APECED, let alone the more complex autoimmune diseases. Yet altogether, the findings of this thesis work bring us one step closer to finding out why and how APECED and common autoimmune diseases arise.

Molecular Pathways of Disturbed Sleep and Depression: Studies on Adenosine and Gene Expression Patterns

Background: Adenosine is a potent sleep-promoting substance, and one of its targets is the basal forebrain. Fairly little is known about its mechanism of action in the basal forebrain and about the receptor subtype mediating its regulating effects on sleep homeostasis. Homeostatic deficiency might be one of the causes of the profoundly disturbed sleep pattern in major depressive disorder, which could explain the reduced amounts of delta-activity-rich stages 3 and 4. Since major depression has a relatively high heritability, and on the other hand adenosine regulates sleep homeostasis and might also be involved in mood modulation, adenosine-related genes should be considered for their possible contribution to a predisposition for depression and disturbed sleep in humans. Depression is a complex disorder likely involving the abnormal functioning of several genes. Novel target genes which could serve as the possible common substrates for depression and comorbid disturbed sleep should be identified. In this way specific brain areas related to sleep regulation should be studied by using animal model of depression which represents more homogenous phenotype as compared to humans. It is also important to study these brain areas during the development of depressive-like features to understand how early changes could facilitate pathophysiological changes in depression. Aims and methods: We aimed to find out whether, in the basal forebrain, adenosine induces recovery non-rapid eye movement (NREM) sleep after prolonged waking through the A1 or/and A2A receptor subtype. A1 and A2A receptor antagonists were perfused into the rat basal forebrain during 3 h of sleep deprivation, and the amount of NREM sleep and delta power during recovery NREM sleep were analyzed. We then explored whether polymorphisms in genes related to the metabolism, transport and signaling of adenosine could predispose to depression accompanied by signs of disturbed sleep. DNA from 1423 individuals representative of the Finnish population and including controls and cases with depression, depression accompanied by early morning awakenings and depression accompanied by fatigue, was used in the study to investigate the possible association between polymorphisms from adenosine-related genes and cases. Finally to find common molecular substrates of depression and disturbed sleep, gene expression changes were investigated in specific brain areas in the rat clomipramine model of depression. We focused on the basal forebrain of 3-week old clomipramine-treated rats which develop depressive-like symptoms later in adulthood and on the hypothalamus of adult female clomipramine-treated rats. Results: Blocking of the A1 receptor during sleep deprivation resulted in a reduction of the recovery NREM sleep amount and delta power, whereas A2A receptor antagonism had no effect. Polymorphisms in adenosine-related genes SLC29A3 (equilibrative nucleoside transporter type 3) in women and SLC28A1 (concentrative nucleoside transporter type 1) in men associated with depression alone as well as when accompanied by early morning awakenings and fatigue. In Study III the basal forebrain of postnatal rats treated with clomipramine displayed disturbances in gamma-aminobutyric acid (GABA) receptor type A signaling, in synaptic transmission and possible epigenetic changes. CREB1 was identified as a common transcription denominator which also mediates epigenetic regulation. In the hypothalamus the major changes included the expression of genes in GABA-A receptor pathway, K+ channel-related, glutamatergic and mitochondrial genes, as well as an overexpression of genes related to RNA and mRNA processing. Conclusions: Adenosine plays an important role in sleep homeostasis by promoting recovery NREM sleep via the A1 receptor subtype in the basal forebrain. Also adenosine levels might contribute to the risk of depression with disturbed sleep, since the genes encoding nucleoside transporters showed the strongest associations with depression alone and when accompanied by signs of disturbed sleep in both women and men. Sleep and mood abnormalities in major depressive disorder could be a consequence of multiple changes at the transcriptional level, GABA-A receptor signaling and synaptic transmission in sleep-related basal forebrain and the hypothalamus.

Rhetoric and Representation : Exploring the Cultural Meaning of the Natural Sciences in Contemporary Popular Science Writing and Literature

Kirjallisuuden- ja kulttuurintutkimus on viimeisten kolmen vuosikymmenen aikana tullut yhä enenevässä määrin tietoiseksi tieteen ja taiteen suhteen monimutkaisesta luonteesta. Nykyään näiden kahden kulttuurin tutkimus muodostaa oman kenttänsä, jolla niiden suhdetta tarkastellaan ennen kaikkea dynaamisena vuorovaikutuksena, joka heijastaa kulttuurimme kieltä, arvoja ja ideologisia sisältöjä. Toisin kuin aiemmat näkemykset, jotka pitävät tiedettä ja taidetta toisilleen enemmän tai vähemmän vastakkaisina pyrkimyksinä, nykytutkimus lähtee oletuksesta, jonka mukaan ne ovat kulttuurillisesti rakentuneita diskursseja, jotka kohtaavat usein samankaltaisia todellisuuden mallintamiseen liittyviä ongelmia, vaikka niiden käyttämät metodit eroavatkin toisistaan. Väitöskirjani keskittyy yllä mainitun suhteen osa-alueista popularisoidun tietokirjallisuuden (muun muassa Paul Davies, James Gleick ja Richard Dawkins) käyttämän kielen ja luonnontieteistä ideoita ammentavan kaunokirjallisuuden (muun muassa Jeanette Winterson, Tom Stoppard ja Richard Powers) hyödyntämien keinojen tarkasteluun nojautuen yli 30 teoksen kattavaa aineistoa koskevaan tyylin ja teemojen tekstianalyysiin. Populaarin tietokirjallisuuden osalta tarkoituksenani on osoittaa, että sen käyttämä kieli rakentuu huomattavassa määrin sellaisille rakenteille, jotka tarjoavat mahdollisuuden esittää todellisuutta koskevia argumentteja mahdollisimman vakuuttavalla tavalla. Tässä tehtävässä monilla klassisen retoriikan määrittelemillä kuvioilla on tärkeä rooli, koska ne auttavat liittämään sanotun sisällön ja muodon tiukasti toisiinsa: retoristen kuvioiden käyttö ei näin ollen edusta pelkkää tyylikeinoa, vaan se myös usein kiteyttää argumenttien taustalla olevat tieteenfilosofiset olettamukset ja auttaa vakiinnuttamaan argumentoinnin logiikan. Koska monet aikaisemmin ilmestyneistä tutkimuksista ovat keskittyneet pelkästään metaforan rooliin tieteellisissä argumenteissa, tämä väitöskirja pyrkii laajentamaan tutkimuskenttää analysoimalla myös toisenlaisten kuvioiden käyttöä. Osoitan myös, että retoristen kuvioiden käyttö muodostaa yhtymäkohdan tieteellisiä ideoita hyödyntävään kaunokirjallisuuteen. Siinä missä popularisoitu tiede käyttää retoriikkaa vahvistaakseen sekä argumentatiivisia että kaunokirjallisia ominaisuuksiaan, kuvaa tällainen sanataide tiedettä tavoilla, jotka usein heijastelevat tietokirjallisuuden kielellisiä rakenteita. Toisaalta on myös mahdollista nähdä, miten kaunokirjallisuuden keinot heijastuvat popularisoidun tieteen kerrontatapoihin ja kieleen todistaen kahden kulttuurin dynaamisesta vuorovaikutuksesta. Nykyaikaisen populaaritieteen retoristen elementtien ja kaunokirjallisuuden keinojen vertailu näyttää lisäksi, kuinka tiede ja taide osallistuvat keskusteluun kulttuurimme tiettyjen peruskäsitteiden kuten identiteetin, tiedon ja ajan merkityksestä. Tällä tavoin on mahdollista nähdä, että molemmat ovat perustavanlaatuisia osia merkityksenantoprosessissa, jonka kautta niin tieteelliset ideat kuin ihmiselämän suuret kysymyksetkin saavat kulttuurillisesti rakentuneen merkityksensä.

Children and adolescents in full-time special education : an epidemiological and magnetic resonance imaging study

The need for special education (SE) is increasing. The majority of those whose problems are due to neurodevelopmental disorders have no specific aetiology. The aim of this study was to evaluate the contribution of prenatal and perinatal factors and factors associated with growth and development to later need for full-time SE and to assess joint structural and volumetric brain alterations among subjects with unexplained, familial need for SE. A random sample of 900 subjects in full-time SE allocated into three levels of neurodevelopmental problems and 301 controls in mainstream education (ME) provided data on socioeconomic factors, pregnancy, delivery, growth, and development. Of those, 119 subjects belonging to a sibling-pair in full-time SE with unexplained aetiology and 43 controls in ME underwent brain magnetic resonance imaging (MRI). Analyses of structural brain alterations and midsagittal area and diameter measurements were made. Voxel-based morphometry (VBM) analysis provided detailed information on regional grey matter, white matter, and cerebrospinal fluid (CSF) volume differences. Father’s age ≥ 40 years, low birth weight, male sex, and lower socio-economic status all increased the probability of SE placement. At age 1 year, one standard deviation score decrease in height raised the probability of SE placement by 40% and in head circumference by 28%. At infancy, the gross motor milestones differentiated the children. From age 18 months, the fine motor milestones and those related to speech and social skills became more important. Brain MRI revealed no specific aetiology for subjects in SE. However, they had more often ≥ 3 abnormal findings in MRIs (thin corpus callosum and enlarged cerebral and cerebellar CSF spaces). In VBM, subjects in full-time SE had smaller global white matter, CSF, and total brain volumes than controls. Compared with controls, subjects with intellectual disabilities had regional volume alterations (greater grey matter volumes in the anterior cingulate cortex bilaterally, smaller grey matter volume in left thalamus and left cerebellar hemisphere, greater white matter volume in the left fronto-parietal region, and smaller white matter volumes bilaterally in the posterior limbs of the internal capsules). In conclusion, the epidemiological studies emphasized several factors that increased the probability of SE placement, useful as a framework for interventional studies. The global and regional brain MRI findings provide an interesting basis for future investigations of learning-related brain structures in young subjects with cognitive impairments or intellectual disabilities of unexplained, familial aetiology.

Computational fluid dynamics simulations in aerosol and nucleation studies

Nucleation is the first step in the formation of a new phase inside a mother phase. Two main forms of nucleation can be distinguished. In homogeneous nucleation, the new phase is formed in a uniform substance. In heterogeneous nucleation, on the other hand, the new phase emerges on a pre-existing surface (nucleation site). Nucleation is the source of about 30% of all atmospheric aerosol which in turn has noticeable health effects and a significant impact on climate. Nucleation can be observed in the atmosphere, studied experimentally in the laboratory and is the subject of ongoing theoretical research. This thesis attempts to be a link between experiment and theory. By comparing simulation results to experimental data, the aim is to (i) better understand the experiments and (ii) determine where the theory needs improvement. Computational fluid dynamics (CFD) tools were used to simulate homogeneous onecomponent nucleation of n-alcohols in argon and helium as carrier gases, homogeneous nucleation in the water-sulfuric acid-system, and heterogeneous nucleation of water vapor on silver particles. In the nucleation of n-alcohols, vapor depletion, carrier gas effect and carrier gas pressure effect were evaluated, with a special focus on the pressure effect whose dependence on vapor and carrier gas properties could be specified. The investigation of nucleation in the water-sulfuric acid-system included a thorough analysis of the experimental setup, determining flow conditions, vapor losses, and nucleation zone. Experimental nucleation rates were compared to various theoretical approaches. We found that none of the considered theoretical descriptions of nucleation captured the role of water in the process at all relative humidities. Heterogeneous nucleation was studied in the activation of silver particles in a TSI 3785 particle counter which uses water as its working fluid. The role of the contact angle was investigated and the influence of incoming particle concentrations and homogeneous nucleation on counting efficiency determined.