Spin Polarization and Normal Reflection at Nanoscale Point Contacts

This thesis presents point-contact measurements between superconductors (Nb, Ta, Sn,Al, Zn) and ferromagnets (Co, Fe, Ni) as well as non-magnetic metals (Ag, Au, Cu, Pt).The point contacts were fabricated using the shear method. The differential resistanceof the contacts was measured either in liquid He at 4.2 K or in vacuum in a dilutionrefrigerator at varying temperature down to 0.1 K. The contact properties were investigatedas function of size and temperature. The measured Andreev-reflection spectrawere analysed in the framework of the BTK model – a three parameter model that describescurrent transport across a superconductor - normal conductor interface. Theoriginal BTK model was modified to include the effects of spin polarization or finitelifetime of the Cooper pairs. Our polarization values for the ferromagnets at 4.2 K agree with the literature data, but the analysis was ambiguous because the experimental spectra both with ferromagnets and non-magnets could be described equally well either with spin polarization or finite lifetime effects in the BTK model. With the polarization model the Z parametervaries from almost 0 to 0.8 while the lifetime model produces Z values close to 0.5. Measurements at lower temperatures partly lift this ambiguity because the magnitude of thermal broadening is small enough to separate lifetime broadening from the polarization. The reduced magnitude of the superconducting anomalies for Zn-Fe contacts required an additional modification of the BTK model which was implemented as a scaling factor. Adding this parameter led to reduced polarization values. However, reliable data is difficult to obtain because different parameter sets produce almost identical spectra.

Formin proteins in normal tissues and cancer

The actin cytoskeleton is a dynamic structure that determines cell shape. Actin turnover is mandatory for migration in normal and malignant cells. In epithelial cancers invasion is frequently accompanied by epithelial to mesenchymal transition (EMT). In EMT, cancer cells acquire a migratory phenotype through transcriptional reprogramming. EMT requires substantial re-organization of actin. During the past decade, new actin regulating proteins have been discovered. Among these are members of the formin family. To study formin expression in tissues and cells, antibodies for detection of formin proteins FMNL1 (Formin-like protein 1), FMNL2 (Formin-like protein 2) and FHOD1 (Formin homology 2 domain containing protein 1) were used. The expression of formins was characterized in normal tissues and selected cancers using immunohistochemistry. The functional roles of formins were studied in cancer cell lines. We found that FMNL2 is widely expressed. It is a filopodial component in cultured melanoma cells. In clinical melanoma, FMNL2 expression has prognostic significance. FHOD1 is a formin expressed in mesenchymal cell types. FHOD1 expression is increased in oral squamous cell carcinoma (SCC) EMT. Importantly, FHOD1 participates in invasion of cultured oral SCC cells. FMNL1 expression is low in normal epithelia, but high in leukocytes and smooth muscle cells. Expression of FMNL1 can be found in carcinoma; we detected FMNL1 expressing cells in basal type of breast cancer. Our results indicate that formins are differentially expressed in normal tissues and that their expression may shift in cancer. Functionally FMNL2 and FHOD1 participate in processes related to cancer progression. Studying formins is increasingly important since they are potential drug targets.

Genetic, prenatal and postnatal determinants of weight gain and obesity in young children – The STEPS Study

Genetic, Prenatal and Postnatal Determinants of Weight Gain and Obesity in Young Children – The STEPS Study University of Turku, Faculty of Medicine, Department of Paediatrics, University of Turku Doctoral Program of Clinical Investigation (CLIPD), Turku Institute for Child and Youth Research. Conditions of being overweight and obese in childhood are common health problems with longlasting effects into adulthood. Currently 22% of Finnish boys and 12% of Finnish girls are overweight and 4% of Finnish boys and 2% of Finnish girls are obese. The foundation for later health is formed early, even before birth, and the importance of prenatal growth on later health outcomes is widely acknowledged. When the mother is overweight, had high gestational weight gain and disturbances in glucose metabolism during pregnancy, an increased risk of obesity in children is present. On the other hand, breastfeeding and later introduction of complementary foods are associated with a decreased obesity risk. In addition to these, many genetic and environmental factors have an effect on obesity risk, but the clustering of these factors is not extensively studied. The main objective of this thesis was to provide comprehensive information on prenatal and early postnatal factors associated with weight gain and obesity in infancy up to two years of age. The study was part of the STEPS Study (Steps to Healthy Development), which is a follow-up study consisting of 1797 families. This thesis focused on children up to 24 months of age. Altogether 26% of boys and 17% of girls were overweight and 5% of boys and 4% of girls were obese at 24 months of age according to New Finnish Growth references for Children BMI-for-age criteria. Compared to children who remained normal weight, the children who became overweight or obese showed different growth trajectories already at 13 months of age. The mother being overweight had an impact on children’s birth weight and early growth from birth to 24 months of age. The mean duration of breastfeeding was almost 2 months shorter in overweight women in comparison to normal weight women. A longer duration of breastfeeding was protective against excessive weight gain, high BMI, high body weight and high weight-for-length SDS during the first 24 months of life. Breast milk fatty acid composition differed between overweight and normal weight mothers, and overweight women had more saturated fatty acids and less n-3 fatty acids in breast milk. Overweight women also introduced complementary foods to their infants earlier than normal weight mothers. Genetic risk score calculated from 83 obesogenic- and adiposity-related single nucleotide polymorphisms (SNPs) showed that infants with a high genetic risk for being overweight and obese were heavier at 13 months and 24 months of age than infants with a low genetic risk, thus possibly predisposing to later obesity in obesogenic environment. Obesity Risk Score showed that children with highest number of risk factors had almost 6-fold risk of being overweight and obese at 24 months compared to children with lowest number of risk factors. The accuracy of the Obesity Risk Score in predicting overweight and obesity at 24 months was 82%. This study showed that many of the obesogenic risk factors tend to cluster within children and families and that children who later became overweight or obese show different growth trajectories already at a young age. These results highlight the importance of early detection of children with higher obesity risk as well as the importance of prevention measures focused on parents. Keywords: Breastfeeding, Child, Complementary Feeding, Genes, Glucose metabolism, Growth, Infant Nutrition Physiology, Nutrition, Obesity, Overweight, Programming

Opettajattareksi sopimaton? Diskurssianalyysi seminaarien naisoppilaiden poikkeavuuden tulkinnasta ja kontrollista Suomessa 1860 -1960 -luvuilla

Tutkimus sijoittuu konstruktivismin ja kasvatuksen historian alueille. Tutkin diskurssianalyysin keinoin miten opettajiksi opiskelevien tyttö- ja naisoppilaiden poikkeavuuden tulkintoja on luotu, ylläpidetty ja uusinnettu 1860-1960 -lukujen Suomessa. Huomio on siinä miten opettajaseminaarien tyttö- ja naisoppilaiden käyttäytymistä on tulkittu poikkeavaksi opettajakokousten pöytäkirjojen teksteissä; miten poikkeavuutta on luotu diskursseilla - ja miten diskurssit ja niiden tulkinnat ovat olleet sukupuolitettuja. Tutkimusaiheeseen diskurssianalyysi soveltuu niin metodiksi kuin viitekehykseksikin, koska poikkeavuuden, normaalin ja epänormaalin rakentuminen tapahtuu kielenkäytön, vuorovaikutuksen ja sosiaalisen toiminnan keskinäisissä suhteissa. Pyrkimyksenä on tietoisuuden lisääminen niistä prosesseista, joissa näitä poikkeavuuden tulkintoja luotiin. Aineistoni koostuu rangaistustapauksista, jotka ovat kirjattu viiden opettajaseminaarin opettajakokousten pöytäkirjoihin vuosien 1863 - 1962 välisenä aikana. Rikkomustapauksia on yhteensä 1436, joista 194 tyttöoppilaiden tekemiä. Ajanjakso alkaa kansalaisyhteiskunnan ja kansanopetuksen synnystä ja päättyy peruskoulun alkuvaiheisiin. Vaikka seminaarien virallinen ja julkinen säännöstö oli kohdistettu yhtälailla nais- ja miesoppilaille, sisälsivät diskursseihin kätkeytyvät normistot seminaarien tyttö- ja naisoppilaille omat erilliset rajat, joiden ylittäminen teki heistä poikkeavia. Tyttö- ja naisoppilaiden poikkeavuus opettajaseminaareissa on ollut poikkeamista Jumalan säätämästä järjestyksestä, jossa naisella on määrätty paikkansa, asemansa ja tehtävänsä. Kun poika- ja miesoppilaiden normeista ja seminaarien säännöistä poikkeamisia on käsitelty opettajakokouksissa rikoksina, on tyttö- ja naisoppilaiden rikkeitä pyritty näkemään sairauden kaltaisina moraalia ja ymmärrystä heikentävinä tiloina. Ennen kaikkea ne ovat olleet rikkomuksia oikeanlaista naiseutta eli ”tosinaiseuden” mallia vastaan. Naisopettajuuden malli kansan äitinä ja mallikansalaisena sekä nöyrän, alistuvan, vaatimattoman ja säyseän ”tosinaisen” mallit olivat lähes yhdenmukaiset ja ne ovat luoneet ja ylläpitäneet tyttö- ja naisoppilaiden toiseutta. Diskurssit, joilla tätä toiseutta ylläpidettiin, elivät opettajaseminaarien pöytäkirjateksteissä liki sadan vuoden ajan vain painotuserojen muuttuessa hieman. Toivon työni herättävän pohdintaa siitä, mitä saattaisivat olla oman aikamme vastaavanlaiset itsestäänselvyydet, jotka otamme annettuina ja jotka kyseenalaistamattomina totuuksina rajoittavat niin kasvatettavien kuin kasvattajienkin omaksi itsekseen tulemista.