| 1. |
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| 2. |
- Wu, Xuping, et al.
(författare)
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Telomerase antagonist imetelstat inhibits esophageal cancer cell growth and increases radiation-induced DNA breaks
- 2012
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Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - : Elsevier BV. - 0167-4889 .- 1879-2596. ; 1823:12, s. 2130-2135
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Tidskriftsartikel (refereegranskat)abstract
- Telomerase is mainly active in human tumor cells, which provides an opportunity for a therapeutic window on telomerase targeting. We sought to evaluate the potential of the thio-phosphoramidate oligonucleotide inhibitor of telomerase, imetelstat, as a drug candidate for treatment of esophageal cancer. Our results showed that imetelstat inhibited telomerase activity in a dose-dependent manner in esophageal cancer cells. After only 1. week of imetelstat treatment, a reduction of colony formation ability of esophageal cancer cells was observed. Furthermore, long-term treatment with imetelstat decreased cell growth of esophageal cancer cells with different kinetics regarding telomere lengths. Short-term imetelstat treatment also increased γ-H2AX and 53BP1 foci staining in the esophageal cancer cell lines indicating a possible induction of DNA double strand breaks (DSBs). We also found that pre-treatment with imetelstat led to increased number and size of 53BP1 foci after ionizing radiation. The increase of 53BP1 foci number was especially pronounced during the first 1 h of repair whereas the increase of foci size was prominent later on. This study supports the potential of imetelstat as a therapeutic agent for the treatment of esophageal cancer.
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| 3. |
- wu, xuping, et al.
(författare)
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The effect of the telomerase antagonist Imetelstat in esophageal carcinoma
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Telomerase is mainly active in human tumor cells, which provides an opportunity for a therapeutic window on telomerase targeting. We sought to evaluate the potential of the thio-phosphoramidate oligonucleotide inhibitor of telomerase, Imetelstat, as a drug candidate for treatment of esophageal cancer. Our results showed that Imetelstat inhibited telomerase activity in a dose-dependent manner in esophageal cancer cells. After only one week of Imetelstat treatment, a reduction of colony formation ability of esophageal cancer cells was observed. Furthermore, long-term treatment with Imetelstat decreased cell growth of esophageal cancer cells with different kinetics regarding telomere lengths. Cell cycle analysis demonstrated that short-term treatment with Imetelstat resulted in increased percentage of cells in G1 phase. Short-term Imetelstat treatment also increased γ-H2AX and 53BP1 foci staining in the esophageal cancer cell lines indicating a possible induction of DNA double strand breaks (DSBs). We also found that pre-treatment with Imetelstat led to increased number and size of 53BP1 foci after ionizing radiation. The increase of 53BP1 foci number was especially pronounced during the first 1 h of repair whereas the increase of foci size was prominent later on. This study supports the potential of Imetelstat as a therapeutic agent for the treatment of esophageal cancer.
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| 4. |
- Adell, Johan, 1980, et al.
(författare)
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Thermal diffusion of Mn through GaAs overlayers on (Ga, Mn)As
- 2011
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 23:8
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Tidskriftsartikel (refereegranskat)abstract
- Thermally stimulated diffusion of Mn through thin layers of GaAs has been studied by x-ray photoemission. (Ga, Mn)As samples with 5 at% Mn were capped with 4, 6 and 8 monolayer (ML) GaAs, and Mn diffusing through the GaAs was trapped on the surface by means of amorphous As. It was found that the out-diffusion is completely suppressed for an 8 ML thick GaAs film. The short diffusion length is attributed to an electrostatic barrier formed at the (Ga, Mn)As/GaAs interface.
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| 5. |
- Agui, A., et al.
(författare)
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Direct observation of interface effects of thin AlAs(100) layers buried in GaAs
- 2000
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 166:1-4, s. 309-312
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Aryasetiawan, F., et al.
(författare)
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Calculations of Hubbard U from first-principles
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : The American Physical Society. - 1098-0121 .- 1550-235X. ; 74:12, s. Article number 125106-
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Tidskriftsartikel (refereegranskat)abstract
- The Hubbard U of the 3d transition metal series as well as SrVO3, YTiO3, Ce, and Gd has been estimated using a recently proposed scheme based on the random-phase approximation. The values obtained are generally in good accord with the values often used in model calculations but for some cases the estimated values are somewhat smaller than those used in the literature. We have also calculated the frequency-dependent U for some of the materials. The strong frequency dependence of U in some of the cases considered in this paper suggests that the static value of U may not be the most appropriate one to use in model calculations. We have also made comparison with the constrained local density approximation (LDA) method and found some discrepancies in a number of cases. We emphasize that our scheme and the constrained local density approximation LDA method theoretically ought to give similar results and the discrepancies may be attributed to technical difficulties in performing calculations based on currently implemented constrained LDA schemes.
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| 7. |
- Aryasetiawan, F., et al.
(författare)
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Energy loss spectra and plasmon dispersions in alkali metals : Negative plasmon dispersion in Cs
- 1994
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 73:12, s. 1679-1682
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Tidskriftsartikel (refereegranskat)abstract
- We present ab initio calculations of the energy loss spectra and plasmon dispersions of the alkali metals Na, K, Rb, and Cs within the random phase approximation, including band structure effects and core electrons as well as local field effects, due to inhomogeneity in the induced charge density. Band structure effects are found to cause a negative dispersion in Cs.
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| 8. |
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| 9. |
- Aryasetiawan, F., et al.
(författare)
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GW approximation with self-screening correction
- 2012
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 85:3, s. 035106-
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Tidskriftsartikel (refereegranskat)abstract
- The GW approximation takes into account electrostatic self-interaction contained in the Hartree potential through the exchange potential. However, it has been known for a long time that the approximation contains self-screening error, as is evident in the case of the hydrogen atom. When applied to the hydrogen atom, the GW approximation does not yield the exact result for the electron removal spectra because of the presence of self-screening: the hole left behind is erroneously screened by the only electron in the system that is no longer present. We present a scheme to take into account self-screening and show that the removal of self-screening is equivalent to including exchange diagrams, as far as self-screening is concerned. The scheme is tested on a model hydrogen dimer and it is shown that the scheme yields the exact result to second order in (Uο-Uι)/2t, where Uο and Uι are, respectively, the on-site and off-site Hubbard interaction parameters and t is the hopping parameter.
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| 10. |
- Aryasetiawan, F., et al.
(författare)
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GW spectral functions of Gd and NiO
- 1996
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 54:8, s. 5353-5357
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Tidskriftsartikel (refereegranskat)abstract
- The spectral functions of highly correlated systems Gd and NiO have been calculated within the GW approximation. In the case of Gd, satellites are found at the positions of the experimental main peaks. However, some quasiparticle weight remains at the local density eigenvalue but its weight is unusually small (0.3). In NiO, satellite structure is observed at around -10 eV when starting from the local density Hamiltonian. It is found, however, that the satellite intensity is reduced towards self-consistency and almost disappears. © 1996 The American Physical Society.
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| 11. |
- Aryasetiawan, F., et al.
(författare)
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Modern theory of orbital magnetic moment in solids
- 2019
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 128, s. 87-108
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic moment in a solid is usually associated with the electron spins but there is an additional contribution due to the orbital motion of the electrons. For a finite system such as an atom or molecule the orbital moment can be readily calculated. However, for a periodic system the formula used for finite systems becomes ill-defined due to the presence of the position operator. In the last decade a modern theory of orbital magnetization that allows for a rigorous calculation of the magnetic moment of periodic crystals has been developed. This article provides a survey of the theoretical development of this new topic as well as recent, albeit a few, applications of the new formula to real materials. Although the original theory was worked out for non-interacting systems, there has been recent progress in the theory of orbital magnetic moment of interacting electrons in solids. To include the effects of electron-electron interactions two approaches have been proposed, one based on current spin density functional theory and another on the many-body Green's function method. The two approaches are very different but both methods provide convenient yet rigorous means of including the effects of exchange and correlations beyond the commonly used local density approximation of density functional theory.
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| 12. |
- Aryasetiawan, F., et al.
(författare)
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Multiple Plasmon Satellites in Na and Al Spectral Functions from Ab Initio Cumulant Expansion
- 1996
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 77:11, s. 2268-2271
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Tidskriftsartikel (refereegranskat)abstract
- The valence photoemission spectra of alkali metals exhibit multiple plasmon satellite structure. The calculated spectral functions within the GW approximation show only one plasmon satellite at too large binding energy. In this Letter we use the cumulant expansion approach to obtain the spectral functions of Na and Al from ab initio calculations including the effects of band structure. The GW spectral functions are dramatically improved and the positions of the multiple plasmon satellites are in very good agreement with experiment while their intensities cannot be explained from intrinsic effects only.
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| 13. |
- Bashir, Tariq, 1981-, et al.
(författare)
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Cellulosic Smart Textile Fibers based on Organic Electronics
- 2016
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Konferensbidrag (refereegranskat)abstract
- The paradigm shift of merging structural properties of materials with other functionalities prevails and cellulose based fibres are no exception. For the realisation of so called smart materials, including smart textiles, electrical conductivity is of special importance, enabling sensorics, signal transmission, energy supply, energy generation, and actuation. We here discuss taking use of the advancement within the organic electronics community of conjugated polymeric systems producing smart textile fibres for inclusion into garment as well as interior and technical textiles. Specifically, poly(3,4-ethylenedioxythiophene) known as PEDOT is studied as a model system. PEDOT has relevance being a working horse within the organic electronics community. Our emerging pilot line is based on creating conductivity by vapour polymerization of EDOT monomers on an oxidant coated textile fibre where these could be taken from arrange of materials. Here we focus on cellulose based fibres. It is shown that Tencell-Lyocell is a suitable substrate offering many anchoring sites and that multiple depositions with layers deposited directly on each other decreased the resistance from 5.1 (± 1.6) kΩ/10 cm to 1.0 (± 0.1) kΩ/10 cm, for one layer and multiple layers respectively. Furthermore, adding 15 wt. % of the copolymer PEG-PPG-PEG to the oxidant solution decreased the resistance from 6.8 (± 1.2) kΩ/10 cm to 3.9 (± 0.8) kΩ/10 cm.
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| 14. |
- Bergkvist, Goran, et al.
(författare)
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Immediate Loading of Implants in the Edentulous Maxilla : Use of an Interim Fixed Prosthesis Followed by a Permanent Fixed Prosthesis: A 32-Month Prospective Radiological and Clinical Study
- 2009
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 11:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to prospectively evaluate the survival rate of splinted and immediately loaded Straumann sandblasted, large-grit, acid-etched, solid-screw dental implants in the edentulous maxilla after 32 months of loading. Twenty-eight patients (mean age 63 years) with edentulous maxillae received 168 implants (six each) and an implant-supported fixed interim prosthesis within 24 hours after surgery. After a mean healing time of 15 weeks, the patients received permanent screw-retained prostheses. Clinical and radiological examinations were made at implant placement and after 8, 20, and 32 months of loading. All permanent prostheses were removed at the 32-month follow-up; implant stability was checked with a torque device, and the implant stability quotient was determined with resonance frequency analysis. Mean marginal bone loss from baseline to 8 months after loading was 1.6 mm (SD 1.16; p = .094), from 8 to 20 months 0.41 mm (SD 0.63; p = .094), and from 20 to 32 months 0.08 mm (SD 0.49; p = .039). The 32-month cumulative survival rate was 98.2%. The 32-month survival of solid-screw implants - immediately loaded within 24 hours after placement - was similar to survival rates reported for solid-screw implants with conventional loading. Immediate loading and splinting of implants in the edentulous maxilla is a viable treatment alternative.
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| 15. |
- Bergkvist, Göran, et al.
(författare)
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Immediately loaded implants supporting fixed prostheses in the edentulous maxilla : A preliminary clinical and radiologic report
- 2005
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Ingår i: International Journal of Oral & Maxillofacial Implants. - 0882-2786 .- 1942-4434. ; 20:3, s. 399-405
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the survival rate of immediately loaded ITI sand-blasted, large-grit, acid-etched (SLA) solid-screw dental implants in the edentulous maxilla after 8 months of loading. Materials and Methods: Twenty-eight patients (mean age 63 years) with edentulous maxillae each received 6 implants and 1 implant-supported fixed provisional prosthesis within 24 hours after surgery. After a mean healing time of 15 weeks, the patient received a definitive, screw-retained, implant-supported fixed prosthesis. A total of 168 implants were placed. Clinical parameters were registered after 1 month of loading with the implant-supported fixed prostheses as well as 8 months after implant place ment. Radiologic examinations and assessments were made at implant placement and after 8 months. Results: The mean marginal bone level at implant placement was 1.6 mm (range 0 to 5.1, SD 1.1) apical of the reference point (the implant shoulder). The mean marginal bone level at the 8-month follow-up was 3.2 mm (range 0.4 to 5.9, SD 1.1) apical of the reference point. Three implants failed during the healing period. Discussion: The improved results in the present study might be a result of the positive effect of splinting the implants immediately after placement Conclusion: ITI SLA solid-screw implants immediately loaded (ie, loaded within 24 hours of placement) and supporting fixed prostheses had successful survival rates after 8 months. The present results constitute a solid base line for future follow-up studies.
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| 16. |
- Boström, Curt-Åke, et al.
(författare)
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Luftkvalitetsmätningar i ett antal tätorter i sydöstra Sverige tre vintersäsonger -98/99, 99/00 & 00/01
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I föreliggande rapport redovisas mätningar av luftkvaliteten avseende trafikrelaterade luftföroreningar, kväveoxider (NOX som NO+NO2), ozon (O3) samt lättflyktiga kolväten (VOC) i ett antal tätorter i regionen (Blekinge, Jönköpings, Kalmar, Kronobergs och Östergötlands län). I varje ort har mätningar skett i två punkter (98/99), i ett hårt trafikbelastat gaturum resp. i urban bakgrund. Mätningarna vintersäsongen 00/01 utökades med ytterligare en trafikbelastad mätpunkt Mätningarna har visat att med diffusionsprovtagare och en samordnad strategi kan man få ett jämförelsematerial användbart för bedömning av luftföroreningssituationen i många tätorter och trafikmiljöer. Mätningarna har även visat på vilken skillnad som kan förväntas i halt mellan förmodade hårt belastade miljöer och den urbana bakgrunden. Även i mindre tätorter kan halterna av trafikrelaterade luftföroreningar bli relativt höga i förhållande till gräns-/riktvärden och miljökvalitetsnor
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| 17. |
- Carlsson, Jan, et al.
(författare)
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AWITAR Prestudy
- 2015
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Rapport (refereegranskat)
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| 18. |
- Chauhan, H. S., et al.
(författare)
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Direct- and inverse-photoemission investigations of the electronic structure of Cd(0001)
- 1993
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 48:7, s. 4729-4734
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Tidskriftsartikel (refereegranskat)abstract
- Photoemission and inverse angle-resolved photoemission spectra are presented for Cd(0001). The data are interpreted in terms of interband transitions, density-of-states effects, and excitations of surface states.
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| 19. |
- Di Marco, Igor, et al.
(författare)
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Electron correlations in MnxGa1-xAs as seen by resonant electron spectroscopy and dynamical mean field theory
- 2013
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 4, s. 6-
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Tidskriftsartikel (refereegranskat)abstract
- After two decades since the discovery of ferromagnetism in manganese-doped gallium arsenide, its origin is still debated, and many doubts are related to the electronic structure. Here we report an experimental and theoretical study of the valence electron spectrum of manganese-doped gallium arsenide. The experimental data are obtained through the differences between off- and on-resonance photo emission data. The theoretical spectrum is calculated by means of a combination of density-functional theory in the local density approximation and dynamical mean field theory, using exact diagonalization as impurity solver. Theory is found to accurately reproduce measured data and illustrates the importance of correlation effects. Our results demonstrate that the manganese states extend over a broad range of energy, including the top of the valence band, and that no impurity band splits-off from the valence band edge, whereas the induced holes seem located primarily around the manganese impurity.
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| 20. |
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| 21. |
- Fransson, A-L, et al.
(författare)
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Temperature variation in newborn babies: importance of physical contact with the mother.
- 2005
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Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1359-2998 .- 1468-2052. ; 90:6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hypothermia is a major cause of deterioration and death in the neonatal period. Temperature deviations are key signs of illness. OBJECTIVE: To determine normal patterns of temperature variation in newborn babies and the influence of external factors. METHODS: Abdominal and foot skin temperature were continuously recorded in 27 healthy full term babies during the first two days of life and related to the care situation-that is, whether the baby was with the mother or in its cot. The recordings were made using no wires to avoid interference with the care of the neonate. Ambient temperature was close to 23 degrees C during the study period. RESULTS: Mean rectal and abdominal and foot skin temperature were lower on day 1 than day 2. The foot skin temperature was directly related to the care situation, being significantly higher when the baby was with the mother. The abdominal skin temperature was much less influenced by external factors. When the neonates were with their mothers, the mean difference between rectal temperature and abdominal skin temperature was 0.2 degrees C compared with a mean difference between rectal temperature and foot skin temperature of 1.5 degrees C, indicating a positive heat balance. In the cot the corresponding temperature differences were 0.7 degrees C and 7.5 degrees C. A temperature difference between rectal and foot skin temperature of 7-8 degrees C indicates a heat loss close to the maximum for which a neonate can compensate (about 70 W/m2). CONCLUSION: This study emphasises the importance of close physical contact with the mothers for temperature regulation during the first few postnatal days.
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| 22. |
- Gotfredsen, Klaus, et al.
(författare)
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Implants and/or teeth: consensus statements and recommendations.
- 2008
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Ingår i: Journal of oral rehabilitation. - : Wiley. - 1365-2842 .- 0305-182X. ; 35:Suppl 1, s. 2-8
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Forskningsöversikt (refereegranskat)abstract
- In August 23-25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboration with the Danish Society of Oral Implantology arranged a consensus conference on the topic 'Implants and/or teeth'. It was preceded by a workshop in which eight focused questions were raised and answered in eight review articles using a systematic approach. Twenty-eight academicians and clinicians discussed the eight review papers with the purpose to reach consensus on questions relevant for the topic. At the conference the consensus statements were presented as well as lectures based on the review articles. In this article the methods used at the consensus workshop are briefly described followed by the statements with comments.
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| 23. |
- Gunnarsson, O., et al.
(författare)
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Information from photoemission spectral weights and shapes
- 2001
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 117-118, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 24. |
- Hertting, Krister, 1972-, et al.
(författare)
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Ping pong health! : A table tennis intervention for improved health at the workplace
- 2018
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Ingår i: The Science and Practice of Racket Sport for Improved Performance and Health: Special Focus on Table Tennis. - Halmstad : Halmstad University. - 9789163971297 ; , s. 22-23
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Konferensbidrag (refereegranskat)abstract
- Introduction: Physical activity has a positive impact on physical and psychological well-being (Delisle, Werch, Wong, Bian, & Weiler, 2010), as well as social relations and skills development (Lamu & Olsen, 2016; Perkins & Williamon, 2014). Adopting a “healthy organization” culture through health programs, with strong senior and middle management support, and using interventions can promote health at workplaces (Rajaratnam et. al., 2014). We, therefore, consider it relevant to have physical activity, social relations and skill development as the starting point in a tabletennis intervention at the workplace.Aim: The aim was to develop, implement, and evaluate an intervention for improving health and wellbeing in the workplace by introducing table tennis.Methods and results: The intervention design consisted of two workshops and five table tennis sessions. Thirteen employees from a warehouse within the retail sector participated in the intervention. The participants had various backgrounds in table tennis and sport in general, different motives to participate, and came from different groups of employees (management and stock). After an introductory workshop, two table tennis coaches held one training session a week over the fiveweek intervention period. The employees were divided in to two groups and each group had a 45-minute session. The evaluation is in progress at present. Pre- and post-measurement has been conducted using health questionnaires Short Form 36 Health Survey (SF-36) and International Physical Activity Questionnaire (IPAQ). These will be analysed using a Bayesian paired t-test analysis. Based on the results of the questionnaire focus group interviews will be conducted with participants. Three focus groups of 4-5 participants in each group. The questions will focus on 24 experiences of the intervention and reflections on future directions for table-tennis and wellbeing activities at the workplace. Finally, there will be a workshop pointing out future directions for sport-based health activities at the workplace.
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| 25. |
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| 26. |
- Johansson, Gunnar, et al.
(författare)
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Asthma treatment preference study : a conjoint analysis of preferred drug treatments
- 2004
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Ingår i: Chest. - : Elsevier BV. - 0012-3692 .- 1931-3543. ; 125:3, s. 916-923
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Assessment of patient preferences for attributes of asthma treatments. METHODS: Two hundred ninety-eight patients (age range, 18 to 60 years) from 15 centers in Sweden completed a questionnaire concerning their asthma, and ranked 18 alternative treatments using conjoint analysis. Patients were receiving treatment with either inhaled corticosteroids (ICS) and short-acting bronchodilator (n = 123) or ICS and long-acting bronchodilator (separate inhalers, n = 87; combination inhaler, n = 88). Attributes analyzed were maintenance treatment, additional reliever, time to onset and duration of reliever, number of symptom-free days (SFDs) per month, and out-of-pocket cost per month. RESULTS: Conjoint analysis showed that the most important aspect of treatment was SFD. Forty percent of the patients had CONCLUSION: SFDs were the most important attribute in asthma treatment. Patients were willing to pay for a switch to their preferred treatment. The most favored treatments were a reliever therapy that is both rapid and long acting and a combination inhaler for both maintenance and as-needed use.
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| 27. |
- Kanski, Janusz, 1946, et al.
(författare)
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Electronic structure of (Ga,Mn)As revisited
- 2017
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Ingår i: New Journal of Physics. - : Institute of Physics (IOP). - 1367-2630. ; 19:2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The detailed nature of electronic states mediating ferromagnetic coupling in dilute magnetic semiconductors, specifically (Ga,Mn)As, has been an issue of long debate. Two confronting models have been discussed emphasizing host band vs. impurity band carriers. Using angle resolved photoemission we show that the electronic structure of the (Ga,Mn)As system is significantly modified from that of GaAs throughout the valence band. Close to the Fermi energy, the presence of Mn induces a strong mixing of the bulk bands of GaAs, which results in the appearance of a highly dispersive band in the gap region of GaAs.For Mn concentrations above 1% the band reaches the Fermi level, and can thus host the delocalized holes needed for ferromagnetic coupling. Overall, our data provide a firm evidence of delocalized carriers belonging to the modified host valence band.
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| 28. |
- Kanski, Janusz, 1946, et al.
(författare)
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Mn-induced modifications of Ga 3d photoemission from (Ga, Mn)As: evidence for long range effects
- 2012
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 24:43, s. 1-435802
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Tidskriftsartikel (refereegranskat)abstract
- Using synchrotron based photoemission, we have investigated the Mn-induced changes in Ga 3d core level spectra from as-grown Ga(1-x)Mn(x)As. Although Mn is located in Ga substitutional sites, and therefore does not have any Ga nearest neighbors, the impact of Mn on the Ga core level spectra is pronounced even at Mn concentrations in the region of 0.5%. The analysis shows that each Mn atom affects a volume corresponding to a sphere with around 1.4 nm diameter.
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| 29. |
- Karlsson, Krister, 1961-, et al.
(författare)
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A many-body approach to spin-wave excitations in itinerant magnetic systems
- 2000
-
Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 12:34, s. 7617-7631
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 30. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Chemical shifts for monovalent, divalent and trivalent Cu compounds
- 1992
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 4:3, s. 895-909
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Tidskriftsartikel (refereegranskat)abstract
- The authors study the chemical shift of the Cu 2p core level for Cu 2O, CuO and NaCuO2, where Cu is formally monovalent, divalent and trivalent, respectively. They find that the binding energy increases with the valence, as expected, although the variation in the number of 3d electrons is small and the trivalent Cu atom is found to have a smaller net positive charge than the monovalent or divalent Cu. The origin of the calculated chemical shifts is analysed and the relation with the chemical valence is discussed.
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| 31. |
- Karlsson, Krister, et al.
(författare)
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Chromatographic characterization of substance P endopeptidase in the rat brain reveals affected enzyme activity following heat stress
- 2006
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Ingår i: Biomedical Chromatography. - : Wiley. - 0269-3879 .- 1099-0801. ; 20:1, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a study of substance P endopeptidase (SPE)-like activity in various regions of the brain from male rats subjected to heat stress (HS). The enzyme activity was found to be affected in several brain areas including cerebellum, cerebral cortex, hippocampus, hypothalamus[sol ]thalamus and the spinal cord following HS. Significant increases in SPE activity were observed in, for example, hippocampus and the spinal cord. SPE-containing extracts from hippocampus were pooled and subsequently purified by size exclusion chromatography (using a Superdex® 75 HR column) and by anion-exchange chromatography (using Resource Q® column). The gel permeation chromatography separated the SPE-like activity into two fractions, one of which was suggested to be identical to neutral endopeptidase owing to its molecular size and inhibitory profile. The other active enzyme fraction behaved in conformity with SPE, previously identified in human cerebrospinal fluid. The activity of the purified fraction of these two enzymes was found to be increased (27%) in HS-treated animals.
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| 32. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Core level chemical shifts and line shapes for systems with different valencies and Cu-O networks
- 2000
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Ingår i: International Journal of Modern Physics B. - : World Scientific. - 0217-9792 .- 1793-6578. ; 14:32, s. 3791-3830
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 33. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Cu 2p chemical shifts for YBa2Cu3O6.5 : Valence of the Cu atoms
- 1992
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 45:13, s. 7559-7562
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Tidskriftsartikel (refereegranskat)abstract
- We study the chemical shift of three different Cu atoms in YBa2Cu3O6.5, and compare the results with the formally mono-, di-, and trivalent model compounds Cu2O, CuO, and NaCuO2. We find similar chemical shifts between Cu in the empty chains, Cu in the planes, and Cu in the intact chains as between the Cu atoms in the model compounds. This suggests that the different Cu atoms in YBa2Cu3O6.5 have formal valences of approximately 1,2, and 3. © 1992 The American Physical Society.
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| 34. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Cuprate Core-Level Line Shapes for Different Cu-O Networks
- 1999
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 82:17, s. 3528-3531
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 35. |
- Karlsson, Krister, 1961-
(författare)
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Electronic Structure Calculations: Materials with Weak and Strong Correlations
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to studies of various electronic properties which can be extracted from photoemission spectroscopy. Both weakly and strongly correlated systems are discussed, ranging from free electron metal surfaces to strongly correlated copper oxide compounds. In order to study such a variety of systems, different calculational schemes have to be employed. This work is mainly based on band structure calculations using the local density approximation. However, for strongly correlated systems the need for model Hamiltonians is crucial. Subjects discussed are: * inverse photoemission spectra from the Cd(0001) surface obtained by a multiple scattering formalism. The results are in good agreement with recent experimental data. Especially, the one-step model is used to demonstrate image states excitations by secondary beams. * artificial structures, such as semiconductor heterojunctions and short-period superlattices, which are of vital importance for modern electronic devices. A method for tuning the band offset at semiconductor interfaces is proposed; by varying (n,m) for the GaAs/(AlAs)n(GaAs)m interface, the magnitude of the valence band offset can be designed. The metallic superlattice Mo/V was also studied, with emphasis on the application of hydrogen storage. * Schottky barrier heights. Final state screening effects can influence the Schottky barrier height, as deduced from measured core level shifts. According to our calculations, such effects may be of the order 0.1-0.2 eV. * chemical shifts in Cu2O, CuO and NaCuO2, where the Cu atom is formally mono-, di- and trivalent. We find similar chemical shifts between Cu atoms in YBa2Cu3O6.5 as between the Cu atoms in the model compounds. This suggests that different Cu atoms in YBa2Cu3O6.5 are formally mono-, di- and trivalent. The Cu 2p core level spectra were calculated using the Anderson impurity model, with parameters obtained from ab initio calculations. The results are related to the formal valence of Cu, and can be explained by a charge counting argument.
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| 36. |
- Karlsson, Krister, et al.
(författare)
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Exchange-correlation kernel in time-dependent density functional theory derived from many-body theory
- 2004
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Ingår i: International Journal of Modern Physics B. - : World Scientific. - 0217-9792. ; 18:7, s. 1055-1067
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Tidskriftsartikel (refereegranskat)abstract
- We derive a simplified Bethe–Salpeter equation for calculating optical absorption based on the assumption of a local electron–hole interaction. The original four-point equation for the kernel is reduced to a two-point one. A connection to the exchange–correlation kernel in time-dependent density functional theory can be established. The resulting fxc is found to be -W/2 where W contains only the short-range (local) part of the Coulomb screened interaction. This simple approximation was successfully applied to optical absorption spectra of some excitonic crystals, reproducing not only the continuum excitons but also the bound ones.
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| 37. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Final-state effects in photoemission from metal-semiconductor interfaces
- 1991
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 67:2, s. 236-239
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter we stress the importance of final-state effects in photoelectron spectroscopy. In particular, we address the problem of Schottky-barrier formation, as studied via core-level shifts in photoemission. We have calculated the shift of the core-level distribution when a semiconductor surface is covered with a metal, using a wave-vector-dependent image-screening model. We conclude that final-state effects, which are generally neglected in this context, are in fact quite important. This conclusion is supported by experimental observations reported in the literature. © 1991 The American Physical Society.
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| 38. |
- Karlsson, Krister, et al.
(författare)
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Method for calculating the electronic structure of correlated materials from a truly first-principles LDA+U scheme
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : The American Physical Society. - 1098-0121 .- 1550-235X. ; 81:24, s. 245113-
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for calculating the electronic structure of correlated materials based on a truly first-principles local-density approximation (LDA)+U scheme. Recently we suggested how to calculate U from first principles, using a method which we named constrained random-phase approximation. The input is simply the Kohn-Sham eigenfunctions and eigenvalues obtained within the LDA. In our proposed self-consistent LDA+U scheme, we calculate the LDA+U eigenfunctions and eigenvalues and use these to extract U. The updated U is then used in the next iteration to obtain a new set of eigenfunctions and eigenvalues and the iteration is continued until convergence is achieved. The most significant result is that our numerical approach is indeed stable: it is possible to find the effective exchange and correlation interaction matrix in a self-consistent way, resulting in a significant improvement over the LDA results, regarding both the bandgap in NiO and the f-band exchange spin splitting in Gd but some discrepancies still remain.
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| 39. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Plasmon lifetime, zone-boundary collective states, and energy-loss spectra of lithium
- 1995
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 52:7, s. 4823-4827
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Tidskriftsartikel (refereegranskat)abstract
- We have calculated the plasmon-width dispersion of Li within the random-phase approximation including the full band structure. The dispersion is found to be negative for small momentum transfers, which is in agreement with experiment. This anomaly is due to the band structure. The energy-loss spectra are found to exhibit a small peak at low energy which can be traced back to the gap at the zone boundaries. This confirms the interpretation of the peak as a so called zone-boundary collective state.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Karlsson, Krister
(författare)
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Self-consistent GW combined with single-site dynamical mean field theory for a Hubbard model
- 2005
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 17:48, s. 7573-7598
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Tidskriftsartikel (refereegranskat)abstract
- We combine the single-site dynamical mean field theory (DMFT) with the non-local GW method. This is done fully self-consistently and we apply our formalism to a one-band Hubbard model. Eventually at self-consistency the full self-energy and polarization operator of the system are retrieved. Some numerical results, in the metallic as well as the insulator regime, are presented and briefly discussed. Depending on the involved interaction (GW) parameters, substantial changes are found when the GW self-energy is incorporated. However, the main point of this work is to demonstrate the applicability of the method, not to make any strict comparison with exact results and experiments.
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| 44. |
- Karlsson, Krister, 1961-, et al.
(författare)
-
Shape of the Cu 2p core level photoemission spectrum for monovalent, divalent and trivalent Cu compounds
- 1992
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 4:11, s. 2801-2816
-
Tidskriftsartikel (refereegranskat)abstract
- We calculate the shape of the 2p core level photoemission spectrum for Cu2O, CuO and NaCuO2, where Cu is formally mono-, di- and trivalent, respectively. Although the number of 3d electrons is similar in the three compounds, there is a large variation in the strength of the d9-like satellite and in the width of the main line. We relate the differences between Cu2O and CuO to the difference in the valence, while for NaCuO2 the detailed form of the hopping matrix elements is also found to be important. © 1992 IOP Publishing Ltd.
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| 45. |
- Karlsson, Krister, 1961-, et al.
(författare)
-
Spin-wave excitation spectra of nickel and iron
- 2000
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 62:5, s. 3006-3009
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 46. |
- Karlsson, Krister, 1972-
(författare)
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Substance P Endopeptidase : Purification and Characterizataion of Enzyme Activity and Evaluation of its Function during Stressful Condition
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purification and biochemical characterization of the substance P (SP) hydrolyzing enzyme, substance P endopeptidase (SPE), have been carried out; with subsequent orientation in neurobiological fundamental processes involved in opioid dependence, withdrawal, and heat-stress.SPE was purified from rat spinal cord, human spinal cord and cerebrospinal fluid (CSF), rat ventral tegemental area (VTA), and rat hippocampus. The enzyme activity was found to release the biologically active fragments SP(1-7) and SP(1-8) as major products. The purified enzymes were characterized with regard to their biochemical and kinetic properties. The typical SPE is neither inhibited by phosphoramidon nor captopril nor phenylmethanesulfonylflourid (PMSF). In comparison to other known proteases SPE differed in characteristics regarding substrate specificity, inhibition-profile, cleavage pattern, and other kinetic parameters. The technically very delicate approach of micro purification of SPE from the rat ventral tegemental area (VTA) (this is a very small tissue), turned out to be possible with the ÄKTA™-purifier system. Studies revealed a crucial role of SPE in a series of clinically important neuropathological conditions, such as opioid tolerance, and withdrawal (SPE, increased); and heat-stress (SPE, increased). These findings emerged from assessment of enzyme activity in hypothalamus, nucleus accumbens (NAc) periaqueductal gray (PAG), pituitary, striatum, substantia nigra (SN), VTA, spinal cord. Viewing the role of SPE in morphine tolerance, it was possible to note regional differences with a decrease in PAG, and striatum, whereas an increase was seen in SN, and VTA. After heat-stress treatment, SPE was raised in several regions (cerebral cortex, hippocampus, diencephalon, cerebellum, spinal cord), and the most precise observation of this was located to the hippocampus structure.
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| 47. |
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| 48. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Tailoring materials for quantum wells : band offsets at (001)-oriented GaAs/(AlAs)n(GaAs)minterfaces
- 1990
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 2:23, s. 5265-5269
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure at the interface between bulk GaAs(001) and short-period superlattices of (AlAs)n(GaAs)m has been calculated using ab initio pseudopotential techniques. The results show that the valence band offsets at such interfaces are very similar to those obtained experimentally for random alloy systems, but superior transport properties are anticipated for the ordered systems.
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| 49. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Theoretical investigation of energy shifts at the GaAs/Au interface
- 1988
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Ingår i: Solid State Communications. - : Elsevier. - 0038-1098 .- 1879-2766. ; 67:4, s. 339-342
-
Tidskriftsartikel (refereegranskat)abstract
- We have used an image screening model to calculate the shift of the Ga(3d−1) core-level distribution when a GaAs surface is covered with metal. Using the GaAs bulk dielectric constant we find a shift of 0.1 (0.18) eV with a mean free path of 25 (8) Å. These shifts are comparable to the measured ones,1 indicating that final-state (image) screening represents an important part of core-level shifts in the vicinity of the interface.
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| 50. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Time-dependent exchange-correlation hole and potential of the electron gas
- 2023
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 107:11
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Tidskriftsartikel (refereegranskat)abstract
- The exchange-correlation hole and potential of the homogeneous electron gas have been investigated within the random-phase approximation, employing the plasmon-pole approximation for the linear density response function. The angular dependence as well as the time dependence of the exchange-correlation hole are illustrated for a Wigner-Seitz radius rs=4 (atomic unit). It is found that there is a substantial cancellation between exchange and correlation potentials in space and time, analogous to the cancellation of exchange and correlation self-energies. Analysis of the sum rule explains why it is more advantageous to use a noninteracting Green function than a renormalized one when calculating the response function within the random-phase approximation and consequently the self-energy within the well-established GW approximation. The present study provides a starting point for more accurate and comprehensive calculations of the exchange-correlation hole and potential of the electron gas with the aim of constructing a model based on the local density approximation as in density functional theory.
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