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  • 1.
    Agui, A.
    et al.
    SPring-8, JAERI, Kouto, Mikazuki, Sayo, Hyogo, Japan ; Department of Physics, Uppsala University, Uppsala, Sweden.
    Såthe, C.
    Department of Physics, Uppsala University, Sweden.
    Guo, J.-H.
    Department of Physics, Uppsala University, Sweden.
    Nordgren, J.
    Department of Physics, Uppsala University, Sweden.
    Mankefors, S.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, T. G.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Direct observation of interface effects of thin AlAs(100) layers buried in GaAs2000In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 166, no 1-4, p. 309-312Article in journal (Refereed)
    Abstract [en]

    A study of the electronic structure of ultrathin AlAs layers buried in GaAs(100) and their interfaces is presented. Al L2,3 soft-X-ray-emission (SXE) spectra from the AlAs layers were measured. The spectra show distinct thickness-dependent features, which are reproduced using ab initio calculations.

  • 2.
    Bergkvist, Anders
    et al.
    Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden / Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, USA.
    Ejdebäck, Mikael
    University of Skövde, Department of Natural Sciences. Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Ubbink, Marcellus
    Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, The Netherlands.
    Karlsson, B. Göran
    Department of Molecular Biotechnology, Chalmers University of Technology, Göteborg, Sweden.
    Surface interactions in the complex between cytochrome f and the E43Q/D44N and E59K/E60Q plastocyanin double mutants as determined by (1)H-NMR chemical shift analysis2001In: Protein Science, ISSN 0961-8368, E-ISSN 1469-896X, Vol. 10, no 12, p. 2623-2626Article in journal (Refereed)
    Abstract [en]

    A combination of site-directed mutagenesis and NMR chemical shift perturbation analysis of backbone and side-chain protons has been used to characterize the transient complex of the photosynthetic redox proteins plastocyanin and cytochrome f. To elucidate the importance of charged residues on complex formation, the complex of cytochrome f and E43Q/D44N or E59K/E60Q spinach plastocyanin double mutants was studied by full analysis of the (1)H chemical shifts by use of two-dimensional homonuclear NMR spectra. Both mutants show a significant overall decrease in chemical shift perturbations compared with wild-type plastocyanin, in agreement with a large decrease in binding affinity. Qualitatively, the E43Q/D44N mutant showed a similar interaction surface as wild-type plastocyanin. The interaction surface in the E59K/E60Q mutant was distinctly different from wild type. It is concluded that all four charged residues contribute to the affinity and that residues E59 and E60 have an additional role in fine tuning the orientation of the proteins in the complex.

  • 3.
    Brodin, Anders
    et al.
    Department of Theoretical Ecology, Lund University, Sweden.
    Jönsson, K. Ingemar
    Department of Theoretical Ecology, Lund University, Sweden.
    Holmgren, Noél
    University of Skövde, Department of Natural Sciences.
    Optimal energy allocation and behaviour in female raptorial birds during the nestling period2003In: Ecoscience, ISSN 1195-6860, Vol. 10, no 2, p. 140-150Article in journal (Refereed)
    Abstract [en]

    In many raptors and owls the male is the main provider of food in the early phase of the nestling period while the female incubates the eggs and broods the young. In the nestling period the female often helps the male to feed the young, but the factors affecting whether and when she leaves the brood to hunt have not been investigated in detail. We present a dynamic state variable model that analyses female behaviour and fat storage dynamics over the nestling period. The results show that in the first half of the nestling period the female faces a conflict between the need to brood the young and the need to hunt to provision them with food. This conflict arises because the energy needs of the young peak early in the nestling period, at a time when they still cannot thermoregulate and therefore need brooding from the female. The most critical period is the second nestling week, when both female and nestling fat reserves will decrease to low levels. Large female fat reserves in the early nestling period provide a solution to this conflict and are essential for successful breeding. Stochasticity in male provisioning is thus not needed to explain why females should be fat when the eggs hatch. Under normal circumstances, the female broods during the first two weeks and leaves the young only if hunting is absolutely necessary. After the second week the energy requirements are relaxed, and whether the female assists the male in hunting or not depends on factors such as male hunting success, environmental stochasticity, and energy requirements of the young. Our model provides a framework for empirical investigations on female behaviour during breeding in raptors, owls, and other birds with marked division of labour.

  • 4.
    Butenko, Melinka A.
    et al.
    Division of Cell and Molecular Biology, University of Oslo, Norway.
    Patterson, Sara E.
    Department of Horticulture, University of Wisconsin-Madison, USA.
    Grini, Paul E.
    Division of Cell and Molecular Biology, University of Oslo, Norway.
    Stenvik, Grethe-Elisabeth
    Division of Cell and Molecular Biology, University of Oslo, Norway.
    Amundsen, Silja S.
    Division of Cell and Molecular Biology, University of Oslo, Norway.
    Mandal, Abul
    University of Skövde, Department of Natural Sciences.
    Aalen, Reidunn B.
    Division of Cell and Molecular Biology, University of Oslo, Norway.
    Inflorescence deficient in abscission controls floral organ abscission in Arabidopsis and identifies a novel family of putative Ligands in Plants2003In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 15, no 10, p. 2296-2307Article in journal (Refereed)
    Abstract [en]

    Abscission is an active process that enables plants to shed unwanted organs. Because the purpose of the flower is to facilitate pollination, it often is abscised after fertilization. We have identified an Arabidopsis ethylene-sensitive mutant, inflorescence deficient in abscission (ida), in which floral organs remain attached to the plant body after the shedding of mature seeds, even though a floral abscission zone develops. The IDA gene, positioned in the genomic DNA flanking the single T-DNA present in the ida line, was identified by complementation. The gene encodes a small protein with an N-terminal signal peptide, suggesting that the IDA protein is the ligand of an unknown receptor involved in the developmental control of floral abscission. We have identified Arabidopsis genes, and cDNAs from a variety of plant species, that encode similar proteins, which are distinct from known ligands. IDA and the IDA-like proteins may represent a new class of ligands in plants

  • 5.
    Ejdebäck, Mikael
    et al.
    University of Skövde, Department of Natural Sciences. Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Bergkvist, Anders
    Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Karlsson, B. Göran
    Deptartment of Molecular Biotechnology, Chalmers University of Technology, Göteborg, Sweden.
    Ubbink, Marcellus
    Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, Netherlands.
    Side-chain interactions in the plastocyanin-cytochrome f complex2000In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 39, no 17, p. 5022-5027Article in journal (Refereed)
    Abstract [en]

    Cytochrome f and plastocyanin are redox partners in the photosynthetic electron-transfer chain. Electron transfer from cytochrome f to plastocyanin occurs in a specific short-lived complex. To obtain detailed information about the binding interface in this transient complex, the effects of binding on the backbone and side-chain protons of plastocyanin have been analyzed by mapping NMR chemical-shift changes. Cytochrome f was added to plastocyanin up to 0.3 M equiv, and the plastocyanin proton chemical shifts were measured. Out of approximately 500 proton resonances, 86% could be observed with this method. Nineteen percent demonstrate significant chemical-shift changes and these protons are located in the hydrophobic patch (including the copper ligands) and the acidic patches of plastocyanin, demonstrating that both areas are part of the interface in the complex. This is consistent with the recently determined structure of the complex [Ubbink, M., Ejdebäck, M., Karlsson, B. G., and Bendall, D. S. (1998) Structure 6, 323-335]. The largest chemical-shift changes are found around His87 in the hydrophobic patch, which indicates tight contacts and possibly water exclusion from this part of the protein interface. These results support the idea that electron transfer occurs via His87 to the copper in plastocyanin and suggest that the hydrophobic patch determines the specificity of the binding. The chemical-shift changes in the acidic patches are significant but small, suggesting that the acidic groups are involved in electrostatic interactions but remain solvent exposed. The existence of small differences between the present data and those used for the structure may imply that the redox state of the metals in both proteins slightly affects the structure of the complex. The chemical-shift mapping is performed on unlabeled proteins, making it an efficient way to analyze effects of mutations on the structure of the complex.

  • 6.
    Gunnarsson, O.
    et al.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Schönhammer, K.
    Institut für Theoretische Physik, Universität Göttingen, Germany.
    Allen, J. W.
    Department of Physics, University of Michigan, Ann Arbor, Michigan, USA.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Jepsen, O.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Information from photoemission spectral weights and shapes2001In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 117-118, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Photoemission line shapes can be used to extract important information about ground-state and low-energy properties. This is illustrated for the electron–phonon interaction in C60 molecules, the occupancy and hybridization of the 4f-level in Ce compounds, the effect of the Cu–O network on core-level photoemission in cuprates and the properties of one-dimensional conductors.

  • 7.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario, Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Applications of generalized Perron trees to maximal functions and density bases1998In: Journal of Fourier Analysis and Applications, ISSN 1069-5869, E-ISSN 1531-5851, Vol. 4, no 2, p. 215-227Article in journal (Refereed)
  • 8.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Fractal dimensions of infinite product spaces2004In: International journal of pure and applied mathematics, ISSN 1311-8080, E-ISSN 1314-3395, Vol. 14, no 2, p. 139-167Article in journal (Refereed)
  • 9.
    Hare, Kathryn E.
    et al.
    Department of Pure Mathematics, University of Waterloo, Waterloo, Ontario Canada.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    The size of Max(p) sets and density bases2002In: Journal of Fourier Analysis and Applications, ISSN 1069-5869, E-ISSN 1531-5851, Vol. 8, no 3, p. 259-268Article in journal (Refereed)
  • 10.
    Jansson, Hanna
    et al.
    Center for Structural Biology and Department of Biochemistry and Biophysics, Göteborg University, Sweden.
    Ökvist, Mats
    Center for Structural Biology and Department of Biochemistry and Biophysics, Göteborg University, Sweden.
    Jacobsson, Frida
    Center for Structural Biology and Department of Molecular Biotechnology, Chalmers University of Technology, Göteborg, Sweden.
    Ejdebäck, Mikael
    University of Skövde, Department of Natural Sciences. Center for Structural Biology and Department of Biochemistry and Biophysics, Göteborg University, Sweden.
    Hansson, Örjan
    Center for Structural Biology and Department of Biochemistry and Biophysics, Göteborg University, Sweden.
    Sjölin, Lennart
    Center for Structural Biology and Department of Inorganic Chemistry, Göteborg University, Sweden.
    The crystal structure of the spinach plastocyanin double mutant G8D/L12E gives insight into its low reactivity towards photosystem 1 and cytochrome f2003In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1607, no 2-3, p. 203-210Article in journal (Refereed)
    Abstract [en]

    Plastocyanin (Pc) is a copper-containing protein, which functions as an electron carrier between the cytochrome b(6)f and photosystem 1 (PS1) complexes in the photosynthetic electron transfer (ET) chain. The ET is mediated by His87 situated in the hydrophobic surface in the north region of Pc. Also situated in this region is Leu12, which mutated to other amino acids severely disturbs the ET from cytochrome f and to PS1, indicating the importance of the hydrophobic surface. The crystal structure of the Pc double mutant G8D/L12E has been determined to 2.0 A resolution, with a crystallographic R-factor of 18.3% (R(free)=23.2%). A comparison with the wild-type structure reveals that structural differences are limited to the sites of the mutations. In particular, there is a small but significant change in the hydrophobic surface close to His87. Evidently, this leads to a mismatch in the reactive complex with the redox partners. For PS1 this results in a 20 times weaker binding and an eightfold slower ET as determined by kinetic measurements. The mutations that have been introduced do not affect the optical absorption spectrum. However, there is a small change in the EPR spectrum, which can be related to changes in the copper coordination geometry

  • 11.
    Karlsson, Krister
    et al.
    University of Skövde, Department of Natural Sciences.
    Aryasetiawan, F.
    Joint Research Centre for Atom Technology - Angstrom Technology Partnership, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan.
    A many-body approach to spin-wave excitations in itinerant magnetic systems2000In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 12, no 34, p. 7617-7631Article in journal (Refereed)
    Abstract [en]

    Using a recently developed Green's function formalism, we have calculated the spin-wave spectra and dispersions in Ni and Fe. For Ni(100), the dispersion exhibits two branches as observed experimentally. The calculated higher optical branch is found to be too high in energy when the standard local density approximation band-structure is used but a very good agreement with the measured dispersion is obtained when the exchange splitting is reduced, to correspond to the experimental value of the exchange splitting. We also found a double branch along Ni(111) which is not observed experimentally. For Fe, the calculated dispersion surprisingly exposes a gap midway along Γ-N in disagreement with experimental data. However, an analysis of the temperature-dependent magnetization has predicted a similar gap at the same wave vector, supporting the present calculations.

  • 12.
    Karlsson, Krister
    et al.
    University of Skövde, Department of Natural Sciences.
    Aryasetiawan, F.
    Joint Research Center for Atom Technology-Angstrom Technology Partnership, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan.
    Spin-wave excitation spectra of nickel and iron2000In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 62, no 5, p. 3006-3009Article in journal (Refereed)
    Abstract [en]

    A Green’s function formalism for calculating spin-wave excitations is developed for practical calculations and tested for real solids. The mapping to the Heisenberg Hamiltonian commonly used in spin-wave calculations is avoided, making the formalism suitable for both localized and itinerant magnetic systems. To test the formalism, we have calculated the spin-wave spectra and dispersions of ferromagnetic Fe and Ni. The results prove to be in very good agreement with experiment and some novel features are predicted.

  • 13.
    Karlsson, Krister
    et al.
    University of Skövde, Department of Natural Sciences.
    Gunnarsson, O.
    Max Planck Institut für Festkörperforschung, Stuttgart, Germany.
    Jepsen, O.
    Max Planck Institut für Festkörperforschung, Stuttgart, Germany.
    Core level chemical shifts and line shapes for systems with different valencies and Cu-O networks2000In: International Journal of Modern Physics B, ISSN 0217-9792, Vol. 14, no 32, p. 3791-3830Article in journal (Refereed)
    Abstract [en]

    We have studied the Cu-2p core level photoemission spectrum of a variety of cuprates, mainly focusing on the chemical shift and the shape of the leading peak. The spectra are calculated using the Anderson impurity model and we obtain a very good agreement with the experimental data. We find that the shape of the leading peak depends crucially on the structure of the Cu-O network. The main peak turns out to be quite narrow if the network consists of Cu-O-Cu bond angels of the order of 90°. On the other hand, if the Cu-O atoms are arranged with bond angles of approximately 180°, the main peak becomes substantially broader and contains a rather complicated structure. However, in some cases it is not sufficient only to consider the Cu-O network because interactions with other atoms are also important. In the model compounds Cu2O, CuO and NaCuO2, where Cu is formally monovalent, divalent and trivalent, respectively, we find that the number of 3d electrons is rather similar. Nevertheless, the binding energy increases with the valence as expected from chemical intuition. The spectra exhibit a large variation in the strength of the d9-like satellite and in the width of the main line. We, furthermore, study the chemical shift of three inequivalent Cu atoms in YBa2Cu3O6.5, and compare the results with the model compounds, which suggests that the different Cu atoms in YBa2Cu3O6.5 have formal valences of approximately one, two and three. These findings are analyzed and related to the formal valence.

  • 14.
    Karlsson, Krister
    et al.
    University of Skövde, Department of Natural Sciences. Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Gunnarsson, O.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Jepsen, O.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Cuprate Core-Level Line Shapes for Different Cu-O Networks1999In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 82, no 17, p. 3528-3531Article in journal (Refereed)
    Abstract [en]

    We have studied the Cu core-level photoemission spectra in the Anderson impurity model for cuprates with different Cu-O networks, dimensionalities (zero, one, two, and three) and Cu valencies (two and three). We focus on the shape of the leading peak and obtain very good agreement with the experimental data. We show how the shape of the spectrum is related to the valence electronic structure and the Cu-O network but also that other atoms can play a role.

  • 15.
    Koitzsch, A.
    et al.
    Institute for Solid State Research, IFW Dresden, Germany.
    Fink, J.
    Institute for Solid State Research, IFW Dresden, Germany.
    Golden, M. S.
    Van der Waals-Zeeman Institute, University of Amsterdam, The Netherlands.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Jepsen, O.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Gunnarsson, O.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Miller, L. L.
    Ames Laboratory, Iowa State University, Ames, Iowa, USA.
    Eisaki, H.
    Department of Applied Physics, Stanford University, California, USA.
    Uchida, S.
    Department of Superconductivity, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
    Yang, G.
    School of Metallurgy and Materials, The University of Birmingham, United Kingdom.
    Abell, S.
    School of Metallurgy and Materials, The University of Birmingham, United Kingdom.
    Core-hole screening response in two-dimensional cuprates: A high-resolution x-ray photoemission study2002In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 66, no 2, article id 024519Article in journal (Refereed)
    Abstract [en]

    We have studied the core level photoemission spectra of the two-dimensional cuprates Sr2CuO2Cl2, Sr2CuO2Br2, Ca2CuO2Cl2, Bi2Sr2CaCu2O8+δ, and Nd2CuO4, with particular focus on the screening response to core-hole creation in the Cu−2p3/2 level. The influence of the apex positions on the shape of the so-called main line is investigated, and found to be weak. Additionally, an Anderson impurity model was used to fit the shape of the main lines, obtaining good agreement with the data from Nd2CuO4. For the other compounds, while the energy spread of the two screening channels (local and nonlocal) is well reproduced, the theory underestimates the width of the nonlocally screened feature. The shapes of the main lines are discussed in detail.

  • 16.
    Mankefors, S.
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, T.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Agui, A.
    Department of Physics, Uppsala University, Sweden.
    Såthe, C.
    Department of Physics, Uppsala University, Sweden.
    Guo, J.-H.
    Department of Physics, Uppsala University, Sweden.
    Nordgren, J.
    Department of Physics, Uppsala University, Sweden.
    Theoretical investigation of the thickness dependence of soft-x-ray emission from thin AlAs(100) layers buried in GaAs2000In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 61, no 8, p. 5540-5545Article in journal (Refereed)
    Abstract [en]

    Ultrathin AlAs(100) layers of 1-, 2-, and 5-ML thickness buried in GaAs are investigated by ab initio calculations. Unique experimental soft-x-ray emission spectra are explained in terms of interface effects and changes with layer thickness are found in the density of states. Only the central layer in the 5-ML geometry is bulklike. A valence-band offset of 0.53 eV is also found for this structure, while no offset exists in the 1- and 2-ML cases. Very good agreement is achieved between theory and experiment.

  • 17.
    Mankefors, S.
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Ab initio calculations of soft-x-ray emission from Si(100) layers buried in GaAs1998In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 58, no 16, p. 10551-10556Article in journal (Refereed)
    Abstract [en]

    Calculations of soft-x-ray emission spectra from Si(100) layers buried in GaAs are reported. The local densities of states for Si in As and Ga sites are found to be very different. By comparison with experimental data, this difference allows us to determine the relative amounts of Si in the two types of sites. In the case of a single Si layer we find that 63 (±5)% of the buried atoms are in Ga sites.

  • 18.
    Mankefors, S.
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Theoretical investigation of soft x-ray emission from a Si(100) layer buried in GaAs1998In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 49, no 3, p. 181-184Article in journal (Refereed)
    Abstract [en]

    Calculations of the soft x-ray emission spectrum have been carried out on a buried Si(100) layer in GaAs and compared with experimental data. We find that Si occupies Ga- as well as As-sites and that the local density of states is different for these two cases.

  • 19.
    Mankefors, S.
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Theoretical investigations of As overlayers on InP(110) surfaces1997In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 56, no 24, p. 15847-15852Article in journal (Refereed)
    Abstract [en]

    As adsorption and interaction with InP(110) is investigated by means of total-energy minimization calculations. We find that the As-P exchanged configuration has higher energy than the As/InP(110) epitaxially continued layer structure (ECLS), for all types of As reservoirs considered. In the presence of an additional As layer in ECLS (i.e., 1.5 ML adsorbed As), however, the exchanged configuration is only slightly higher in energy than the nonexchanged one. We conclude that the As-P exchange process is energetically unfavorable, and should in any case not be complete at room temperature, as suggested in a recent report. Our conclusion is supported by results of a photoemission study, including As adsorption, desorption, and redeposition, according to which the process is nonreversible.

  • 20.
    Olesen, Kenneth
    et al.
    Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Ejdebäck, Mikael
    University of Skövde, Department of Natural Sciences. Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Crnogorac, Milan M.
    Department of Chemistry, Iowa State University, Ames, United States.
    Kostić, Nenad M.
    Department of Chemistry, Iowa State University, Ames, United States.
    Hansson, Örjan
    Biochemistry and Biophysics, Department of Chemistry, Göteborg University, Sweden.
    Electron transfer to photosystem 1 from spinach plastocyanin mutated in the small acidic patch: ionic strength dependence of kinetics and comparison of mechanistic models1999In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 38, no 50, p. 16695-16705Article in journal (Refereed)
    Abstract [en]

    A set of plastocyanin (Pc) mutants, probing the small acidic patch (Glu59, Glu60, and Asp61) and a nearby residue, Gln88, has been constructed to provide further insight into the electron transfer process between Pc and photosystem 1. The negatively charged residues were changed into their neutral counterparts or to a positive lysine. All mutant proteins exhibited electron transfer kinetics qualitatively similar to those of the wild type protein over a wide range of Pc concentrations. The kinetics were slightly faster for the Gln88Lys mutant, while they were significantly slower for the Glu59Lys mutant. The data were analyzed with two different models: one involving a conformational change of the Pc-photosystem 1 complex that precedes the electron transfer step (assumed to be irreversible) [Bottin, H., and Mathis, P. (1985) Biochemistry 24, 6453-6460] and another where no conformational change occurs, the electron transfer step is reversible, and dissociation of products is explicitly taken into account [Drepper, F., Hippler, M., Nitschke, W., and Haehnel, W. (1996) Biochemistry 35, 1282-1295]. Both models can account for the observed kinetics in the limits of low and high Pc concentrations. To discriminate between the models, the effects of added magnesium ions on the kinetics were investigated. At a high Pc concentration (0.7 mM), the ionic strength dependence was found to be consistent with the model involving a conformational change but not with the model where the electron transfer is reversible. One residue in the small acidic patch, Glu60, seems to be responsible for the major part of the ionic strength dependence of the kinetics.

  • 21.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    A convergence result for square roots of the Poisson kernel in the bidisk1999In: Mathematica Scandinavica, ISSN 0025-5521, E-ISSN 1903-1807, Vol. 84, no 1, p. 81-92Article in journal (Refereed)
  • 22.
    Rönning, Jan-Olav
    University of Skövde, Department of Natural Sciences.
    Convergence results for the square root of the Poisson kernel1997In: Mathematica Scandinavica, ISSN 0025-5521, E-ISSN 1903-1807, Vol. 81, no 2, p. 219-235Article in journal (Refereed)
  • 23.
    Rönning, Jan-Olav
    et al.
    University of Skövde, Department of Natural Sciences.
    Svensson, Olof
    Linköpings Universitet, Campus Norrköping, Institutionen för teknik och naturvetenskap.
    Convergence for the square root of the Poisson kernel in rank one symmetric spaces against boundary functions with regularity: Preprint Chalmers och Göteborgs Universitet, (79)2001Manuscript (preprint) (Other academic)
  • 24.
    Sjöling, Åsa
    et al.
    Department of Cell and Molecular Biology-Genetics, Göteborg University, Sweden.
    Lindholm, Heléne
    University of Skövde, Department of Natural Sciences.
    Samuelson, E.
    Department of Cell and Molecular Biology-Genetics, Göteborg University, Sweden.
    Yamasaki, Y.
    Otsuka GEN Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
    Watanabe, T. K.
    Otsuka GEN Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
    Tanigami, A.
    Otsuka GEN Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
    Levan, G.
    Department of Cell and Molecular Biology-Genetics, Göteborg University, Sweden.
    Analysis of chromosomal aberrations involving chromosome 1q31-->q53 in a DMBA-induced rat fibrosarcoma cell line: amplification and overexpression of Jak22001In: Cytogenetics and Cell Genetics, ISSN 0301-0171, E-ISSN 1421-9816, Vol. 95, no 3-4, p. 202-209Article in journal (Refereed)
    Abstract [en]

    In a study of DMBA-induced rat fibrosarcomas we repeatedly found deletions and/or amplifications in the long arm of rat chromosome 1 (RNO1). Comparative genome hybridization showed that there was amplification involving RNO1q31-->q53 in one of the DMBA-induced rat fibrosarcoma tumors (LB31) and a cell culture derived from it. To identify the amplified genes we physically mapped rat genes implicated in cancer and analyzed them for signs of amplification. The genes were selected based on their locations in comparative maps between rat and man. The rat proto-oncogenes Ccnd1, Fgf4, and Fgf3 (HSA11q13.3), were mapped to RNO1q43 by fluorescence in situ hybridization (FISH). The Ems1 gene was mapped by radiation hybrid (RH) mapping to the same rat chromosome region and shown to be situated centromeric to Ccnd1 and Fgf4. In addition, the proto-oncogenes Hras (HSA11p15.5) and Igf1r (HSA15q25-->q26) were mapped to RNO1q43 and RNO1q32 by FISH and Omp (HSA11q13.5) was assigned to RNO1q34. PCR probes for the above genes together with PCR probes for the previously mapped rat genes Bax (RNO1q31) and Jak2 (RNO1q51-->q53) were analyzed for signs of amplification by Southern blot hybridization. Low copy number increases of the Omp and Jak2 genes were detected in the LB31 cell culture. Dual color FISH analysis of tumor cells confirmed that chromosome regions containing Omp and Jak2 were amplified and were situated in long marker chromosomes showing an aberrant banding pattern. The configuration of the signals in the marker chromosomes suggested that they had arisen by a break-fusion-bridge (BFB) mechanism.

  • 25.
    Sottile, F.
    et al.
    Laboratoire des Solides Irradiés UMR, Palaiseau, France.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Reining, L.
    Laboratoire des Solides Irradiés UMR, Palaiseau, France.
    Aryasetiawan, F.
    Research Institute for Computational Sciences (RICS), Japan.
    Macroscopic and microscopic components of exchange-correlation interactions2003In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 68, no 20, p. 205112-205122, article id 205112Article in journal (Refereed)
    Abstract [en]

    We consider two commonly used approaches for the ab initio calculation of optical-absorption spectra, namely, many-body perturbation theory based on Green’s functions and time-dependent density-functional theory (TDDFT). The former leads to the two-particle Bethe-Salpeter equation that contains a screened electron-hole interaction. We approximate this interaction in various ways, and discuss in particular the results obtained for a local contact potential. This, in fact, allows us to straightforwardly make the link to the TDDFT approach, and to discuss the exchange-correlation kernel fxc that corresponds to the contact exciton. Our main results, illustrated in the examples of bulk silicon, GaAs, argon, and LiF, are the following. (i) The simple contact exciton model, used on top of an ab initio calculated band structure, yields reasonable absorption spectra. (ii) Qualitatively extremely different fxc can be derived approximatively from the same Bethe-Salpeter equation. These kernels can however yield very similar spectra. (iii) A static fxc, both with or without a long-range component, can create transitions in the quasiparticle gap. To the best of our knowledge, this is the first time that TDDFT has been shown to be able to reproduce bound excitons.

  • 26.
    Springer, M.
    et al.
    Department of Theoretical Physics, University of Lund, Sweden.
    Aryasetiawan, F.
    Department of Theoretical Physics, University of Lund, Sweden.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    First-Principles T-Matrix Theory with Application to the 6 eV Satellite in Ni1998In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 80, no 11, p. 2389-2392Article in journal (Refereed)
    Abstract [en]

    In photoemission spectra of strongly correlated systems one usually observes a satellite structure below the main peak. Description of such satellite structures in the commonly used GW approximation has been found to be insufficient. To account for these satellite structures that originate from short-range correlations, we have developed a T-matrix formalism for performing ab initio calculations on real systems. The method is applied to Ni and we obtain a satellite structure below the Fermi level as well as a reduced exchange splitting. We also found a new interesting satellite structure above the Fermi level, which can be ascribed to particle-particle scattering.

  • 27.
    Sunhede, Stellan
    et al.
    University of Skövde, Department of Natural Sciences.
    Meiere, Diana
    The Faculty of Biology, Riga, Latvia.
    Vedsvampar på ek: 10. Ekskinn, Aleurodiscus disciformis2003In: Ekbladet: medlemsskrift för Ekfrämjandet, ISSN 0283-4839, Vol. 18, p. 27-30Article in journal (Other (popular science, discussion, etc.))
  • 28.
    Sunhede, Stellan
    et al.
    University of Skövde, Department of Natural Sciences.
    Vasiliauskas, Rimvydas
    Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ecology and decay pattern of Inocutis dryophila on Quercus robur2003In: Karstenia, ISSN 0453-3402, Vol. 43, no 2, p. 45-53Article in journal (Refereed)
    Abstract [en]

    The biology of Inocutis dryophila (Berk.) Fiasson & Niemelä was studied on Quercus robur L. in Lithuania, based on 22 host trees. Decay columns caused by the fungus in six oaks,120–180 years old, were examined in detail by dissecting the stems. Length of the decay columns in different trees varied between 4.8 and 11 m. Vegetative compatibility tests with the isolates indicated that each rot column comprised of a single genet of the fungus, and that the rot columns in different trees represented different genets. Basidiocarps of the fungus were recorded from 0.7 to 12.5 m above the ground. Infection routes, forestry, and biodiversity aspects are discussed. Colour photographs are shown of the basidiocarp, decay of different stages, and confrontation tests among cultivated mycelia of the same and different genets.

  • 29.
    Sunhede, Stellan
    et al.
    University of Skövde, Department of Natural Sciences.
    Vasiliauskas, Rimvydas
    Institutionen för skoglig mykologi och patologi, SLU, Uppsala.
    Hotade tickor på ek i Litauen2003In: Svensk botanisk tidskrift, ISSN 0039-646X, Vol. 97, no 5, p. 252-265Article in journal (Refereed)
    Abstract [en]

    Rare and endangered species of Aphyllophorales have been studied on Quercus robur in Lithuania. In total, 5455 trees and 742 stumps of oaks have been investigated in pure oak stands, mixed deciduous woods, mixed coniferous–deciduous woods, parks, and in open landscapes. Fungi in the herbarium BILAS (Vilnius) were examined.

    The ecology, distribution, and status of the following polypores are treated, viz Fistulina hepatica (Schaeff.: Fr.) With., Grifola frondosa (Dicks.: Fr) S.F.Gray, Hapalopilus croceus (Pers.: Fr.) Bond. & Sing, Inocutis dryophila (Berk) Fiasson & Niemelä, Inonotus dryadeus (Pers.: Fr.) Murr., Piptoporus quercinus (Fr.) Pilát, and Polyporus umbellatus (Pers.) ex Fr. Each species is briefly described and localities are listed in detail. All species, except F. hepatica and P. quercinus, are included in the Lithuanian Red List of fungi. We suggest these two species should be added to the list, and classified according to the IUCN categories Near Threatened (NT) and Endangered (EN), respectively.

    The importance of saving the right type of substrate and habitat for the actual species is stressed. Thick dead, standing or fallen trees, and old stumps should not be removed, as F. hepatica, G. frondosa, H. croceus, and P. quercinus may continue to fructify for many years on this type of wood. Suppression of old host trees, formerly growing in a more open environment, is a problem at many sites. A proper clearing around these oaks is necessary to keep the oaks alive as long as possible. The necessity of favouring younger oaks of different age classes in the stands is pointed out, as a continuous supply of thick host trees is needed to preserve the fungi.

    Hapalopilus croceus, one of Europe’s most endangered fungi, fructifies on old thick oaks, a substrate that becomes more and more rare. All Lithuanian host trees of H. croceus are proposed to be preserved (even when dead) together with a sufficient number of oaks in the surroundings. In Sweden, which is still one of the strongholds of H. croceus in Europe, the species is classified as Critically Endangered (CR) and since 2000 also protected.

    The following two oak sites in Lithuania are highly recommended to be preserved, more closely investigated, and managed for the future: Punios Šilas (squares 31, 32 & 38), Alytus district. In this very valuable locality, where many old and thick oaks are suppressed by surrounding younger trees, we found H. croceus (on 11 oaks), I. dryophila, F. hepatica, P. quercinus, and the red-listed beetle Osmoderma eremita (Scop.). “Kauno Ažuolynas” in Kaunas is a unique park with more than 800 mostly old, thick oaks, mixed with, e.g., Tilia. Here we observed F. hepatica, G. frondosa (on 11 oaks), H. croceus (on 8 oaks), and I. dryophila.

  • 30.
    Vos, M.
    et al.
    Research School of Physical Sciences and Engineering, Institute of Advanced Studies, ANU, Canberra, A.C.T. 0200, Australia.
    Kheifets, A. S.
    Research School of Physical Sciences and Engineering, Institute of Advanced Studies, ANU, Canberra, A.C.T. 0200, Australia.
    Weigold, E.
    Research School of Physical Sciences and Engineering, Institute of Advanced Studies, ANU, Canberra, A.C.T. 0200, Australia.
    Canney, S. A.
    Electronic Structure of Materials Centre, Flinders University of South Australia, GPO Box 2100, Adelaide, S.A. 5001, Australia.
    Holm, B.
    Department of Applied Physics, Chalmers University of Technology and Göteborg University, Sweden.
    Aryasetiawan, F.
    Joint Research Centre for Atom Technology, Angstrom Technology Partnership, 1-1-4 Higashi, Tsukuba, Ibaraki 305, Japan.
    Karlsson, Krister
    University of Skövde, Department of Natural Sciences.
    Determination of the energy-momentum densities of aluminium by electron momentum spectroscopy1999In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 11, no 18, p. 3645-3661Article in journal (Refereed)
    Abstract [en]

    The energy-resolved momentum densities of thin polycrystalline aluminium films have been measured using electron momentum spectroscopy (EMS), for both the valence band and the outer core levels. The spectrometer used for these measurements has energy and momentum resolutions of around 1.0 eV and 0.15 atomic units, respectively. These measurements should, in principle, describe the electronic structure of the film very quantitatively, i.e. the dispersion and the intensity can be compared directly with theoretical spectral momentum densities for both the valence band and the outer core levels. Multiple scattering is found to hamper the interpretation somewhat. The core-level intensity distribution was studied with the main purpose of setting upper bounds on these multiple-scattering effects. Using this information we wish to obtain a full understanding of the valence band spectra using different theoretical models of the spectral function. These theoretical models differ significantly and only the cumulant expansion calculation that takes the crystal lattice into account seems to describe the data reasonably well.

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