Dynamic and Static Transmission Electron Microscopy Studies on Structural Evaluation of Au nano islands on Si (100) Surface

Transmission electron microscopy (TEM) study on morphological changes in gold nanostructures deposited on Si (100) upon annealing under different vacuum conditions has been reported. Au thin films of thickness ~2.0 nm were deposited under high vacuum condition (with the native oxide at the interface of Au and Si) using thermal evaporation. In-situ, high temperature (from room temperature (RT) to 850\degreeC) real time TEM measurements showed the evaluation of gold nanoparticles into rectangular/square shaped gold silicide structures. This has been attributed to selective thermal decomposition of native oxide layer. Ex-situ annealing in low vacuum (10-2 mbar) at 850\degreeC showed no growth of nano-gold silicide structures. Under low vacuum annealing conditions, the creation of oxide could be dominating compared to the decomposition of oxide layers resulting in the formation of barrier layer between Au and Si.Comment: 15 pages, 4 figure

Elinaikaisten tekijöiden yhteys keski-iän nikamakokoon:tarkastelussa elinaikainen liikunnallisuus sekä varhainen kasvu

Tiivistelmä. Osteoporoosi on maailmanlaajuinen terveysongelma, joka koskettaa merkittävää osaa väestöstä keski-iästä lähtien. Sille tyypillistä on luukudoksen lujuuden heikentyminen mikro- ja makrotason muutosten seurauksena, mistä johtuu erityisesti kasvanut traumaan liittymättömien matalaenergisten murtumien riski. Selkänikama on yleisin ja usein myös ensimmäinen tällaisen murtuman esiintymiskohta. Nikaman pienen koon tiedetään lisäävän sen murtumariskiä, mutta nikaman kokoa määrittäviä tekijöitä tunnetaan varsin rajallisesti. Tämän tutkimuskokonaisuuden tarkoituksena on ollut tutkia, miten (1) vapaa-ajan yleinen liikunnallisuus, (2) yksittäiset liikuntalajit ja luita kuormittava liikunta, (3) työn fyysiset ominaisuudet sekä (4) varhainen kasvu vaikuttavat keski-iän nikamakokoon. Tutkimusjoukon on muodostanut Pohjois-Suomen syntymäkohortti 1966:n osaotos, johon kuuluneiden lanneranka on magneettikuvattu osana 46-vuotistutkimusta vuosina 2012–2014 (n = 1 540). Elinaikaisen eli lähes 50-vuotisen seurantajakson aikana tutkittavien terveydentilasta sekä elintavoista on kertynyt runsaasti tietoa, jota tutkimuksessa on hyödynnetty. Liikunnallista aktiivisuutta on tiedusteltu 14, 31 ja 46 vuoden kohdalla, lajikohtaista harrastusaktiivisuutta 31 ja 46 vuoden kohdalla ja työn fyysisiä piirteitä niin ikään 31 ja 46 vuoden kohdalla. Tietoa fyysisestä kehityksestä pituuden ja painon suhteen on kerätty syntymästä lähtien. Tutkimusprojekti on onnistunut paljastamaan nikamakoon kannalta potentiaalisesti merkityksellisiä tekijöitä. Naisten elinikäisen vapaa-ajan liikunnallisuuden on havaittu olevan yhteydessä suurentuneeseen keski-iän nikamakokoon. Yhteys on havaittu paitsi yleisen liikunnallisuuden osalta, myös erityisesti luustoa tehokkaasti kuormittavia liikunta- ja urheilulajeja (pallopelit, juoksu) tarkasteltaessa. Miehillä ei ole havaittu yhteyttä liikunnan ja nikamakoon välillä, eikä työn fyysisyys ole näyttänyt olevan yhteydessä nikamakokoon kummallakaan sukupuolella. Nopean varhaislapsuuden painonnousun on havaittu olevan itsenäisesti yhteydessä suurempiin keski-iän nikamiin sekä miehillä että naisilla, kun taas lapsuuden ja nuoruuden ripeä pituuskasvu on heijastunut keski-iän nikamakokoon aikuispituuden kautta. Havaitut yksilöiden väliset erot nikamakoossa ovat maltillisia, mutta tutkimuksen tulosten valossa erityisesti naisten vapaa-ajan liikuntakäyttäytyminen näyttää olevan yhteydessä nikamakokoon ja sitä kautta murtumariskiin. Lisäksi jo varhaisen lapsuuden fyysisen kehityksen perusteella näyttää olevan mahdollista ennustaa keski-iän nikamakokoa ja siten myös nikamamurtuman riskiä kummankin sukupuolen osalta. Kyseessä on väitöskirjaksi tarkoitettu tutkimuskokonaisuus, joka on toteutettu Oulun yliopiston lääketieteellisessä tiedekunnassa vuosina 2015–2017. Poikkitieteellisen tutkimusprojektin ohjaajina ovat toimineet professori Jaakko Niinimäki (radiologia), professori Jaro Karppinen (fysiatria) sekä dosentti Juho-Antti Junno (antropologia). Projektin osatöitä on julkaistu vertaisarvioiduissa tieteellisissä julkaisuissa ja Oura on toiminut näissä ensimmäisenä kirjoittajana. Tekijänoikeudellisista syistä syventävien opintojen raporttina julkaistaan tämä lyhennelmä sekä viitteet toistaiseksi julkaistuihin osatöihin. Täydellinen tutkimusprojektin kuvaus on tarkoitus julkaista väitöskirjan muodossa myöhemmin

Molecular Identification of Eimeria Species in Broiler Chickens in Trinidad, West Indies

Coccidiosis is an intestinal disease of chickens of major economic importance to broiler industries worldwide. Species of coccidia found in chickens include Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, and Eimeria tenella. In recent years, polymerase chain reaction (PCR) has been developed to provide accurate and rapid identification of the seven known Eimeria species of chickens. The aim of this study was to use species-specific real-time PCR (qPCR) to identify which of the seven Eimeria species are present in Trinidad poultry. Seventeen pooled fecal samples were collected from 6 broiler farms (2–5 pens per farm) across Trinidad. Feces were also collected from birds showing clinical signs of coccidiosis in two live bird markets (pluck shops). qPCR revealed the presence of five species of Eimeria (E. acervulina, E. maxima, E. mitis, E. necatrix, and E. tenella), but not E. brunetti or E. praecox. Mixed infections were detected on all broiler farms, and DNA of two highly pathogenic Eimeria species (E. tenella and E. necatrix) was detected in feces taken from clinically sick birds sampled from the two pluck shops

Degenerative cervical spine changes among early career fighter pilots : a 5-year follow-up

Introduction Degenerative changes of the cervical spine often cause disability and flight duty limitations among Finnish Air Force (FINAF) fighter pilots. We aimed to study the effect of +Gz exposure on degenerative changes in the cervical spine by comparing cervical MRIs of FINAF fighter pilots and controls. Methods At baseline, the volunteer study population consisted of 56 20-year-old FINAF male fighter pilots (exposure group) and 56 21-year-old Army and Navy cadets (control group). Both groups underwent MRI of the cervical spine at the baseline and after 5 years. Degenerative changes evaluated using MRI included intervertebral disc (IVD) degeneration (Pfirrmann classification), disc herniations, uncovertebral arthrosis, Schmorl’s nodes, Modic changes, spinal canal stenosis, kyphosis and scoliosis. Results The degree of IVD degeneration in the whole cervical spine increased significantly in both populations with no between-group differences. The prevalence of disc herniations also tended to increase in both populations with no difference in the incidence over the follow-up. However, pilots proved to have more disc herniations at the baseline and at the follow-up. There were virtually no between-group differences in other assessed degenerative changes. Discussion We found that IVD degeneration and the prevalence of disc herniations increased at a similar rate for fighter pilots and non-flying military students when all cervical levels were summed up. The lack of difference may be explained by the relatively low cumulative +Gz exposure during the first 5 years of a pilots’ career

Evidence for Transmission of Bluetongue Virus Serotype 26 through Direct Contact

The aim of this study was to assess the mechanisms of transmission of bluetongue virus serotype 26 (BTV-26) in goats. A previous study, which investigated the pathogenicity and infection kinetics of BTV-26 in goats, unexpectedly revealed that one control goat may have been infected through a direct contact transmission route. To investigate the transmission mechanisms of BTV-26 in more detail an experimental infection study was carried out in which three goats were infected with BTV-26, three goats were kept uninfected, but were housed in direct contact with the infected goats, and an additional four goats were kept in indirect contact separated from infected goats by metal gates. This barrier allowed the goats to have occasional face-to-face contact in the same airspace, but feeding, watering, sampling and environmental cleaning was carried out separately. The three experimentally infected goats did not show clinical signs of BTV, however high levels of viral RNA were detected and virus was isolated from their blood. At 21 dpi viral RNA was detected in, and virus was isolated from the blood of the three direct contact goats, which also seroconverted. The four indirect barrier contact goats remained uninfected throughout the duration of the experiment. In order to assess replication in a laboratory model species of Culicoides biting midge, more than 300 Culicoides sonorensis were fed a BTV-26 spiked blood meal and incubated for 7 days. The dissemination of BTV-26 in individual C. sonorensis was inferred from the quantity of virus RNA and indicated that none of the insects processed at day 7 possessed transmissible infections. This study shows that BTV-26 is easily transmitted through direct contact transmission between goats, and the strain does not seem to replicate in C. sonorensis midges using standard incubation conditions

Evidence for a correlated insulator to antiferromagnetic metal transition in CrN

We investigate the electronic structure of Chromium Nitride (CrN) across the first-order magneto-structural transition at T_N ~ 286 K. Resonant photoemission spectroscopy shows a gap in the 3d partial density of states at the Fermi level and an On-site Coulomb energy U ~ 4.5 eV, indicating strong electron-electron correlations. Bulk-sensitive high resolution (6 meV) laser photoemission reveals a clear Fermi edge indicating an antiferromagnetic metal below T_N. Hard x-ray Cr 2p core-level spectra show T-dependent changes across T_N which originate from screening due to coherent states as substantiated by cluster model calculations using the experimentally observed U. The electrical resistivity confirms an insulator above T_N (E_g ~ 70 meV) which becomes a disordered metal below T_N. The results indicate CrN transforms from a correlated insulator to an antiferromagnetic metal, coupled to the magneto-structural transition.Comment: Submitted to Physical Review Letters (February 2010) 11 pages, 3 figures in the main text, 1 Supplementary Informatio

Classical theta constants vs. lattice theta series, and super string partition functions

Recently, various possible expressions for the vacuum-to-vacuum superstring amplitudes has been proposed at genus $g=3,4,5$. To compare the different proposals, here we will present a careful analysis of the comparison between the two main technical tools adopted to realize the proposals: the classical theta constants and the lattice theta series. We compute the relevant Fourier coefficients in order to relate the two spaces. We will prove the equivalence up to genus 4. In genus five we will show that the solutions are equivalent modulo the Schottky form and coincide if we impose the vanishing of the cosmological constant.Comment: 21 page

Quantum-well states in ultrathin Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces

Ag(111) films were deposited at room temperature onto H-passivated Si(111)-(1x1) substrates, and subsequently annealed at 300 C. An abrupt non-reactive Ag/Si interface is formed, and very uniform non-strained Ag(111) films of 6-12 monolayers have been grown. Angle resolved photoemission spectroscopy has been used to study the valence band electronic properties of these films. Well-defined Ag sp quantum-well states (QWS) have been observed at discrete energies between 0.5-2eV below the Fermi level, and their dispersions have been measured along the GammaK, GammaMM'and GammaL symmetry directions. QWS show a parabolic bidimensional dispersion, with in-plane effective mass of 0.38-0.50mo, along the GammaK and GammaMM' directions, whereas no dispersion has been found along the GammaL direction, indicating the low-dimensional electronic character of these states. The binding energy dependence of the QWS as a function of Ag film thickness has been analyzed in the framework of the phase accumulation model. According to this model, a reflectivity of 70% has been estimated for the Ag-sp states at the Ag/H/Si(111)-(1x1) interface.Comment: 6 pages, 6 figures, submitted to Phys. Rev.