Resistivity of Ca-Al metallic glasses

The resistivity of Ca-Al metallic glass is calculated as a function of temperature and composition. The diffraction model is used, including the partial dynamic structure factors. To account for the blurring of the Fermi surface we propose a new model which preserves the wave-packet character of the scattering electron. The results compare favorably with the experimental measurements available, indicating that the diffraction model is applicable also for high-resistivity systems. The use of t-matrix formulation of scattering is seen essential and the value of the Fermi wave vector to be used is shown to need careful consideration. The Fermi-surface blurring is found to affect the resistivity but the changes are not drastic. The origins of the large resistivity are seen to be in the strong scattering from Ca atoms, as expected, but also in the changes in the atomic and electronic structure.Peer reviewe

Computer simulations of radiation damage in amorphous solids

Microscopic radiation damage in a Lennard-Jones amorphous solid is investigated by computer simulations of collision cascades. Molecular-dynamics simulations with various primary knock-on atom (PKA) energies and directions are carried out. Energy outflow from the computational box is accounted for but electronic losses are neglected. The simulations show the PKA energy to spread rapidly among the nearby atoms, and the atomic trajectories disclose such features as replacement collision sequences and focused chains. Vacancies are created in the central region of the cascade and are surrounded by a cloud of interstitials. The defects mainly disappear independently of each other, the vacancies faster than the interstitials. Recombination plays a minor role. At the end of a simulation all the defects created have vanished and little change in the sample volume or structure is observed. The threshold energy for a permanent displacement is found for various PKA directions. The validity of the modified Kinchin-Pease model for an amorphous solid is discussed.Peer reviewe

Temperature dependence of positron trapping at voids in metals

We report positron-lifetime measurements in void-containing aluminum samples, which show strong temperature dependence for the positron trapping probability. A theory is presented for the positron motion and trapping in a three-dimensional array of large voids, which compares favorably with the experimental data. It is shown that at low temperatures the trapping is transition limited and strongly temperature dependent with a crossover to diffusion-limited and weakly-temperature-dependent behavior at high temperatures.Peer reviewe

Phylogeography of amphi-boreal fish: tracing the history of the Pacific herring Clupea pallasii in North-East European seas

BackgroundThe relationships between North Atlantic and North Pacific faunas through times have been controlled by the variation of hydrographic circumstances in the intervening Arctic Ocean and Bering Strait. We address the history of trans-Arctic connections in a clade of amphi-boreal pelagic fishes using genealogical information from mitochondrial DNA sequence data. The Pacific and Atlantic herrings (Clupea pallasii and C. harengus) have basically vicarious distributions in the two oceans since pre-Pleistocene times. However, remote populations of C. pallasii are also present in the border waters of the North-East Atlantic in Europe. These populations show considerable regional and life history differentiation and have been recognized in subspecies classification. The chronology of the inter-oceanic invasions and genetic basis of the phenotypic structuring however remain unclear.ResultsThe Atlantic and Pacific herrings both feature high mtDNA diversities (large long-term population sizes) in their native basins, but an ocean-wide homogeneity of C. harengus is contrasted by deep east-west Pacific subdivision within Pacific C. pallasii. The outpost populations of C. pallasii in NE Europe are identified as members of the western Pacific C. pallasii clade, with some retained inter-oceanic haplotype sharing. They have lost diversity in colonization bottlenecks, but have also thereafter accumulated abundant new variation. The data delineate three phylogeographic groups within the European C. pallasii: herring from the inner White Sea; herring from the Mezen and Chesha Bays; and a strongly bottlenecked peripheral population in Balsfjord of the Norwegian Sea.ConclusionsThe NE European outposts of C. pallasii are judged to be early post-glacial colonists from the NW Pacific. A strong regional substructure has evolved since that time, in contrast to the apparent broad-scale uniformity maintained by herrings in their native basins. The structure only partly matches the previous biological concepts based on seasonal breeding stocks or geographical subspecies designations. The trans-Arctic herring phylogeography is notably similar to those of the amphi-boreal mollusk taxa Macoma and Mytilus, suggesting similar histories of inter-oceanic connections. We also considered the time dependency of molecular rates, critical for interpreting timing of relatively recent biogeographical events, by comparing the estimates from coding and non-coding mitochondrial regions of presumably different mutation dynamics

Student participatory role profiles in collaborative science learning: Relation of within-group configurations of role profiles and achievement

During collaborative learning, students tend to spontaneously enact different participatory roles that may significantly affect collaborative learning processes. Only few empirical studies to date have investigated groups as systems based on emerging roles and role profiles of the participating students, and how emerging role profile configurations affect achievement. This exploration of students' self-adopted roles investigated the relationship between role profile configurations and achievement. The statistically driven identification of role profiles was based on fine-grained observations of student groups' interactions in two distinct collaborative science-learning settings. While higher achieving groups typically exhibited versatile science-oriented role profile configurations, opinion-based configurations prevailed in lower achieving groups. Although role profiles with a social orientation were rare, a student with a distracting profile can have a significant influence on group work. Consolidated by in-depth case examples, the findings highlight the importance of understanding how collaborating groups' emergent role profiles dynamically interact during collaborative learning and how different role profile configurations relate to achievement

Muistisairaiden liikunnallisen kuntoutuksen vaikuttavuus : Satunnaistettu vertailutukimus

Tutkimuksen tavoitteena oli selvittää satunnaistetulla,kontrolloidulla asetelmalla liikunnallisen harjoittelun vaikuttavuutta kotona asuvien, Alzheimerin tautia sairastavien toimintakyvyn eri ulottuvuuksiin, heidän omaishoitajiensa elämänlaatuun sekä molempien palveluiden käyttöön ja niiden kustannuksiin vuosina 2008–2011. Tutkimukseen osallistui 210 pariskuntaa, joista toinen puoliso oli muistisairaan omaishoitaja. Pariskunnat randomoitiin kolmeen yhtä suureen ryhmään: 1) ryhmäkuntoutusryhmään (liikuntaharjoittelua neljä tuntia kaksi kertaa viikossa päiväkeskuksessa vuoden ajan), 2) kotikuntoutusryhmään (tunti kaksi kertaa viikossa kotona vuoden ajan fysioterapeutin ohjauksessa) ja 3) vertailuryhmään (tavallinen kunnallinen hoito). Tutkimushoitajan haastattelut tehtiin lähtötilanteessa sekä 3:n, 6:n, 12:n ja 24 kuukauden kohdalla. Päätulosmuuttujat olivat muistisairaan ihmisen toimintakyky (mitattiin FIM-toimintakykymittarilla) sekä liikuntakyky (mitattiin Guralnikin liikuntakyky- ja tasapainotesteillä = SPPB). Kotona annetulla räätälöidyllä kuntoutuksella voidaan hidastaa muistisairaiden fyysisen toimintakyvyn (mitattu FIM-mittarilla) heikkenemistä merkitsevästi. Liikuntatesteissä (SPPB) ei ollut eroja ryhmien välillä. Myös kognitiossa näkyi myönteinen muutos toiminnanohjauksen osalta kellotestillä mitattuna kotikuntoutusryhmässä. Ryhmäkuntoutuksessa palveluiden kokonaiskustannusten säästöt olivat merkittävät, joskaan muutokset toimintakyvyssä eivät saavuttaneet tilastollista merkitsevyyttä. Omaisten elämänlaadussa tai muissa mittareissa ei ollut merkitseviä eroja interventioryhmien ja vertailuryhmien välillä. Kaatumiset vähenivät molemmissa interventioryhmissä. Kuolemanvaara näytti pienentyneen kotikuntoutusryhmässä. Tutkimuksessa luotiin kuntoutusmalli, joka parantaa Alzheimerin tautia sairastavien toimintakykyä lisäämättä sosiaali- ja terveyspalveluiden kokonaiskustannuksia.15,00 euro

KSHV infection of endothelial precursor cells with lymphatic characteristics as a novel model for translational Kaposi's sarcoma studies

Author summaryKaposi's sarcoma herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). The main proliferative component of KS, spindle cells, express markers of lymphatic and blood endothelium. Endothelial precursor cells, which are circulating endothelial colony forming cells (ECFCs), have been proposed as the source of spindle cells. Here we examined both blood and lymphatic ECFCs infected with KSHV. Lymphatic ECFCs are readily infected by KSHV, maintain the viral episomes and show modest transformation of the cells, which the infected blood ECFCs and all uninfected ECFCs failed to show. The lymphatic ECFCs express SOX18, which supported the maintenance of high copy numbers of KSHV genomes. The KSHV-infected lymphatic ECFCs persisted in vivo and recapitulated the phenotype of KS tumor cells such as high number of viral genome copies and spindling morphology. These KS tumor cell hallmarks were significantly reduced by SOX18 chemical inhibition using a small molecule SM4 treatment. These data suggest that KSHV-infected lymphatic ECFCs could be the progenitors of KS spindle cells and are a promising model for the translational studies to develop new therapies for KS.Kaposi's sarcoma herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS), a hyperplasia consisting of enlarged malformed vasculature and spindle-shaped cells, the main proliferative component of KS. While spindle cells express markers of lymphatic and blood endothelium, the origin of spindle cells is unknown. Endothelial precursor cells have been proposed as the source of spindle cells. We previously identified two types of circulating endothelial colony forming cells (ECFCs), ones that expressed markers of blood endothelium and ones that expressed markers of lymphatic endothelium. Here we examined both blood and lymphatic ECFCs infected with KSHV. Lymphatic ECFCs are significantly more susceptible to KSHV infection than the blood ECFCs and maintain the viral episomes during passage in culture while the blood ECFCs lose the viral episome. Only the KSHV-infected lymphatic ECFCs (K-ECFCLY) grew to small multicellular colonies in soft agar whereas the infected blood ECFCs and all uninfected ECFCs failed to proliferate. The K-ECFCLYs express high levels of SOX18, which supported the maintenance of high copy number of KSHV genomes. When implanted subcutaneously into NSG mice, the K-ECFCLYs persisted in vivo and recapitulated the phenotype of KS tumor cells with high number of viral genome copies and spindling morphology. These spindle cell hallmarks were significantly reduced when mice were treated with SOX18 inhibitor, SM4. These data suggest that KSHV-infected lymphatic ECFCs can be utilized as a KSHV infection model for in vivo translational studies to test novel inhibitors representing potential treatment modalities for KS.Peer reviewe

Non-axisymmetric accretion on the classical TTS RW Aur A

(Abridged) High-resolution spectroscopic monitoring of RW Aur A was carried out in 1996, 1998 and 1999 with simultaneous B, V photometry. A multicomponent spectrum is revealed with a veiled photospheric spectrum, broad emissions, narrow emission lines of helium, and accretion, wind and shell features. Periodic modulations in many spectral features were found. The photospheric absorption lines show sinusoidal variations in radial velocity with an amplitude of +-6 km/s and a period of about 2.77 days. The radial velocities of the narrow emission lines of He vary with the same period but in anti-phase to the photospheric lines. The equivalent widths of the narrow emissions vary with a phase-shift with respect to the velocity curve. The strength of the red-shifted accretion components of Na D and other lines is also modulated with the same period. The broad emission lines of metals vary mostly with the double period of about 5.5 days. One unexpected result is that no correlation was found between the veiling and the brightness, although both varied in wide ranges. This is partly due to a contribution of the shell absorption to the photospheric line profiles, which make them vary in width and depth thus simulating lower veiling. Most of the observed features can be interpreted in the framework of non-axisymmetric magnetospheric accretion. We consider two possible models. In the first the asymmetry is induced by orbital motion of an invisible, low mass secondary, which also influences the gasflows around the star, the second considers rotational modulation of a single star with an inclined or asymmetric magnetosphere