Vibrational assignments and line shapes in inelastic tunnelling spectroscopy: H on Cu(100)

We have carried out a computational study of the inelastic electron tunneling spectrum (IETS) of the two vibrational modes of a single hydrogen atom on a Cu(100) surface in a scanning tunneling microscopy (STM) junction. This study addresses key issues about vibrational assignment and line shape of observed peaks in IETS within the framework of density functional theory calculations and the Lorente-Persson theory for STM-IETS. We argue that the observation of only a single, broad peak in the STM-IETS [L.J. Lauhon and W. Ho, Phys. Rev. Lett. 85, 4566 (2000)] is not caused by any symmetry restrictions or any cancellation between inelastic and elastic vibrational contributions for one of the two modes but is due to strongly overlapping superposition of the contributions from the two modes caused by the rather large instrumental broadening and the narrow vibrational energy separation between the modes. In particular, we find that this broadening and the large asymmetry of the vibrational line shapes gives rise to substantial apparent vibrational energy shifts of the two modes and decrease their apparent energy separation

Vain aito siemen kelpaa viljelijälle ja siemenliikkeelle

Siementavaran aitoudella tarkoitetaan sitä, että markkinoitava siemen on myyntipakkauksen päällä olevassa vakuuslipukkeessa ilmoitettua lajiketta, eikä siihen ole sekoittunut muiden saman lajin lajikkeiden siemeniä.vo

Structural basis of cytoskeletal regulation by twinfilin

The actin cytoskeleton is required, in all eukaryotic organisms, for several key cellular functions such as cell motility, cytokinesis, and endocytosis. In cells, actin exists either in a monomeric state (G-actin) or in a filamentous form (F-actin). F-actin is the functional form, which can assemble into various structures and produce direct pushing forces that are required for different motile processes. The assembly of actin monomers into complicated three-dimensional structures is tightly regulated by a large number of actin regulating proteins. One central actin regulating protein is twinfilin. Twinfilin consists of two actin depolymerizing-factor homology (ADF-H) domains, which are capable of binding actin, and is conserved from yeast to mammals. Previously it has been shown that twinfilin binds to and sequesters G-actin, and interacts with the heterodimeric capping protein. More recently it has been found that twinfilin also binds to the fast growing actin filament ends and prevents their growth. However, the cellular role of twinfilin and the molecular mechanisms of these interactions have remained unclear. In this study we characterized the molecular mechanisms behind the functions of twinfilin. We demonstrated that twinfilin forms a high-affinity complex with ADP-bound actin monomers (ADP-G-actin). Both ADF-H domains are capable of binding G-actin, but the C-terminal domain contains the high-affinity binding site. Our biochemical analyses identified twinfilin s C-terminal tail region as the interaction site for capping protein. Contrary to G-actin binding, both ADF-H domains of twinfilin are required for the actin filament barbed end capping activity. The C-terminal domain is structurally homologous to ADF/cofilin and binds to filament sides in a similar manner, providing the main affinity for F-actin during barbed end capping. The structure of the N-terminal domain is more distant from ADF/cofilin, and thus it can only associate with G-actin or the terminal actin monomer at the filament barbed end, where it regulates twinfilin s affinity for barbed ends. These data suggest that the mechanism of barbed end capping is similar for twinfilin and gelsolin family proteins. Taken together, these studies revealed how twinfilin interacts with G-actin, filament barbed ends, and capping protein, and also provide a model for how these activities evolved through a duplication of an ancient ADF/cofilin-like domain.Aktiini on yksi konservoituneimmista ja yleisimmistä proteiineista, jota esiintyy kaikkien aitotumallisten organismien kaikissa soluissa. Soluissa aktiiniproteiini kykenee polymerisoitumaan filamenteiksi ja yhdessä nämä filamentit muodostavat solun aktiinitukirangan. Aktiinitukirangan dynaamisilla muutoksilla on ratkaiseva merkitys useissa eukaryoottisten soujen prosesseissa, kuten mm solujen jakautumisessa, solujen liikkeissä, ekso- ja endosytoosissa. Näitä muutoksia välittää lukuisa joukko aktiinia sitovia proteiineja. Yksi näistä proteiineista on twinfliliini. Twinfiliini sitoutuu aktiinimonomeereihin, aktiinifilamenttien kasvua inhiboivaan capping proteiiniin ja aktiinifilamenttien päihin. Tässä työssä tutkimme twinfiliinin biokemiallista vuorovaikutusta sitoutumiskumppaniensa kanssa, sekä näiden vuorovaikutusten rakenteellista perustaa. Tuloksemme paljastivat, mitkä osat twinfiliiniproteiinissa ovat oleellisia näissä sitoutumistapahtumissa. Twinfiliinin domeinien rakenteet, yhdessä biokemiallisten tulosten kanssa, paljastivat miten twinfiliini vuorovaikuttaa aktiinifilamenttien kanssa ja miten tämä aktiivisuus on saattanut kehittyä yhdestä yksinkertaisesta aktiinia sitovasta domeinista

Evaluation of quantitative and qualitative research methods in collecting data about attitudes and behaviour, international software piracy as an example

Siirretty Doriast

Magnetic Resocance Imaging Methods in the Follow-up of Multiple Sclerosis and in Farby Disease

Multiple sclerosis (MS) is a chronic immune-mediated inflammatory disorder of the central nervous system. MS is the most common disabling central nervous system (CNS) disease of young adults in the Western world. In Finland, the prevalence of MS ranges between 1/1000 and 2/1000 in different areas. Fabry disease (FD) is a rare hereditary metabolic disease due to mutation in a single gene coding α-galactosidase A (alpha-gal A) enzyme. It leads to multi-organ pathology, including cerebrovascular disease. Currently there are 44 patients with diagnosed FD in Finland. Magnetic resonance imaging (MRI) is commonly used in the diagnostics and follow-up of these diseases. The disease activity can be demonstrated by occurrence of new or Gadolinium (Gd)-enhancing lesions in routine studies. Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are advanced MR sequences which can reveal pathologies in brain regions which appear normal on conventional MR images in several CNS diseases. The main focus in this study was to reveal whether whole brain apparent diffusion coefficient (ADC) analysis can be used to demonstrate MS disease activity. MS patients were investigated before and after delivery and before and after initiation of diseasemodifying treatment (DMT). In FD, DTI was used to reveal possible microstructural alterations at early timepoints when excessive signs of cerebrovascular disease are not yet visible in conventional MR sequences. Our clinical and MRI findings at 1.5T indicated that post-partum activation of the disease is an early and common phenomenon amongst mothers with MS. MRI seems to be a more sensitive method for assessing MS disease activity than the recording of relapses. However, whole brain ADC histogram analysis is of limited value in the follow-up of inflammatory conditions in a pregnancy-related setting because the pregnancy-related physiological effects on ADC overwhelm the alterations in ADC associated with MS pathology in brain tissue areas which appear normal on conventional MRI sequences. DTI reveals signs of microstructural damage in brain white matter of FD patients before excessive white matter lesion load can be observed on conventional MR scans. DTI could offer a valuable tool for monitoring the possible effects of enzyme replacement therapy in FD.Siirretty Doriast

Multiproxy reconstruction of past methane emissions at Storfjordrenna Pingos site (South of Svalbard) during the last deglaciation

The main ambition of this thesis was to study the relationship between isotopic signature of fossil foraminifera and past methane emission at Storfjordrenna Pingos site (South of Svalbard) during the last deglaciation in context of past climatic changes. Two gravity cores, the core 1070 from the flank of the presently inactive gas hydrate pingo 5 (GHP5) and the core 1069 from the top of the GHP5, were investigated in detail. Combined benthic and planktic δ13C records, visual investigations (SEM-EDS) of the foraminiferal tests and the solid phase composition of the sediment (XRF) revealed interesting and complex methane seepage history at the presently inactive GHP5. Several paleo seepage events were found from deglaciation and Holocene deposits