| 1. |
- Wang, Z., et al.
(författare)
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Genome-wide association analyses of physical activity and sedentary behavior provide insights into underlying mechanisms and roles in disease prevention
- 2022
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 54:9, s. 1332-1344
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Tidskriftsartikel (refereegranskat)abstract
- Although physical activity and sedentary behavior are moderately heritable, little is known about the mechanisms that influence these traits. Combining data for up to 703,901 individuals from 51 studies in a multi-ancestry meta-analysis of genome-wide association studies yields 99 loci that associate with self-reported moderate-to-vigorous intensity physical activity during leisure time (MVPA), leisure screen time (LST) and/or sedentary behavior at work. Loci associated with LST are enriched for genes whose expression in skeletal muscle is altered by resistance training. A missense variant in ACTN3 makes the alpha-actinin-3 filaments more flexible, resulting in lower maximal force in isolated type IIA muscle fibers, and possibly protection from exercise-induced muscle damage. Finally, Mendelian randomization analyses show that beneficial effects of lower LST and higher MVPA on several risk factors and diseases are mediated or confounded by body mass index (BMI). Our results provide insights into physical activity mechanisms and its role in disease prevention. Multi-ancestry meta-analyses of genome-wide association studies for self-reported physical activity during leisure time, leisure screen time, sedentary commuting and sedentary behavior at work identify 99 loci associated with at least one of these traits.
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| 2. |
- Abreu, P, et al.
(författare)
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b-tagging in DELPHI at LEP
- 2004
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 32:2, s. 185-208
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Tidskriftsartikel (refereegranskat)abstract
- The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly.
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| 3. |
- Hakansson, M C, et al.
(författare)
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The electronic structure of In- and As-terminated InAs(001) surfaces
- 1997
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 374:1-3, s. 73-79
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Tidskriftsartikel (refereegranskat)abstract
- The InAs(001) 2 x 4 and 4 x 2 surfaces have been investigated by angle-resolved photoemission. The X(3) and X(5) points were found to be located 6.0 and 2.7 eV below the valence band maximum, respectively, and the dispersion of bulk bands along the Gamma-X direction in the bulk Brillouin zone were well described by a theoretical calculation. From angle-resolved valence band spectra measured along the high symmetry directions [110] and [1(1) over bar0$], three surface induced stares were identified on both the InAs(001)4 x 2 and the InAs(001)2 x 4 surface. (C) 1997 Elsevier Science B.V.
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| 4. |
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| 5. |
- Andersson, C B M, et al.
(författare)
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Surface atomic structure of InAs((111)over-bar)2x2 and InSb((111)over-bar)2x2 studied by core level spectroscopy
- 1996
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 347:1-2, s. 199-206
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Tidskriftsartikel (refereegranskat)abstract
- Surface sensitive high resolution core level spectroscopy has been applied to the molecular beam epitaxy grown InAs((111) over bar)2 x 2 and InSb((111) over bar)2 x 2 surfaces. For both systems the In 4d core level consists of one dominating component while the Group V core levels are deconvoluted into four components. This analysis is consistent with a surface model where the topmost layer consists entirely of arsenic or antimony. In this model, Group V atoms form trimers bound to Group V atoms in the first double layer, leaving a single Group V rest atom per unit cell.
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| 6. |
- He, Z Q, et al.
(författare)
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As overlayer on GaAs(110) studied with photoemission
- 1995
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52:23, s. 16602-16607
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Tidskriftsartikel (refereegranskat)abstract
- As-terminated GaAs(110) surfaces were prepared on ex situ cleaved substrates by molecular-beam epitaxy. The surface stoichiometry was controlled by postgrowth As deposition. Photoemission from a surface covered with a monolayer As was investigated in detail using synchrotron radiation. Two different surface components were found in core-level spectra, which are interpreted as due to adatoms bonding to the surface anions and cations. In the valence-band spectra several surface states were identified, in analogy with previous reports on the isoelectronic Sb/GaAs(110) system. The polarization dependence is not the same, however, which leads us to the conclusion that the adlayer bonding mechanisms are different in the two cases.
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| 7. |
- Olsson, L O, et al.
(författare)
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Core level and valence-band studies of the (111)2x2 surfaces of InSb and InAs
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 53:8, s. 4734-4740
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Tidskriftsartikel (refereegranskat)abstract
- The valence and core electronic surface states on the (111)2X2 surfaces of InSb and InAs have been studied by angle-resolved photoelectron spectroscopy. Similarities in data show that the vacancy-buckling model, which is known to describe the InSb(111)2x2 surface, also applies to InAs(111)2X2. Three surface valence bands are identified and their dispersions are mapped along symmetry directions in the surface Brillouin zone. The In 4d core levels show one surface shifted component while no surface shifted components of the Sb 4d or As 3d core levels could be resolved.
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| 8. |
- Clark, DW, et al.
(författare)
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Associations of autozygosity with a broad range of human phenotypes
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 4957-
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Tidskriftsartikel (refereegranskat)abstract
- In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44–66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding.
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| 9. |
- Girard, R T, et al.
(författare)
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Electronic structure of ZnO(0001) studied by angle-resolved photoelectron spectroscopy
- 1997
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 373:2-3, s. 409-417
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the ZnO(0001) surface was studied by angle-resolved photoelectron spectroscopy. The recorded normal emission spectra give information about the Valence band states as well as the Zn 3d states. The dispersions of the four valence bands observed in the (0001) direction were compared with theory and are in good agreement with recent calculations which consider the Zn 3d electrons as part of the valence band. The Zn 3d states are seen to separate into two groups of four and six bands, which show dispersion with k(perpendicular to). This is in agreement with theoretical results but the location of these states were not accurately predicted. The present photoemission results show that they lie around 10.5 eV below E(F). Two surface states were observed on the (0001) surface. One, at 7.5 eV binding energy, was predicted by theory and is interpreted as arising from the ''back-bondings'' of the Zn 4s-O 2p mixed bulk states. The other one at 4.5 eV below E(F), most likely Zn 4p-0 2p derived, was not predicted by theoretical calculations and this is discussed further in the text. (C) 1997 Elsevier Science B.V.
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| 10. |
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| 11. |
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| 12. |
- Grishin, Michael A., et al.
(författare)
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Anisotropy of electron structure at InAs(111) surfaces by laser pump-and-probe photoemission spectroscopy
- 2005
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 574:1, s. 89-94
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure and the electron dynamics of the clean InAs(111)A 2 x 2 and the InAs(111)B 1 x 1 surfaces have been studied by laser pump-and-probe photoemission spectroscopy. Normally unpopulated electron states above the valence band maximum (VBM) are filled on the InAs(111)A surface due to the conduction band pinning above the Fermi level (E-F). Accompanied by the downward band banding alignment, a charge accumulation layer is confined to the surface region creating a two dimensional electron gas (2DEG). The decay of the photoexcited carriers above the conduction band minimum (CBM) is originated by bulk states affected by the presence of the surface. No occupied states were found on the InAs(111)B 1 x 1 surface. This fact is suggested to be due to the surface stabilisation by the charge removal from the surface into the bulk. The weak photoemission intensity above the VBM on the (111)B surface is attributed to electron states trapped by surface defects. The fast decay of the photoexcited electron states on the (111)A and the (111)B surfaces was found to be tau(111A) less than or equal to 5 ps and tau(111B) less than or equal to 4ps, respectively. We suggest the diffusion of the hot electrons into the bulk is the decay mechanism. (
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| 13. |
- Grishin, Michael A., et al.
(författare)
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Electron structure and electron dynamics at InSb(111)2×2 semiconductor surface
- 2003
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 76:3, s. 299-302
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Tidskriftsartikel (refereegranskat)abstract
- The conduction band electronic structure and the electron dynamics of the clean InSb(111)2 x 2 surface have been studied by laser based pump-and-probe photoemission. The results are compared to earlier studies of the InSb(110) surface. It is found that both the energy location and the time dependence of the photoexcited structures are very similar for the two surfaces. This indicates that the dominant part of the photoemission signal in the conduction band region is due to excitations of electrons in the bulk region and that the surface electronic states play a minor role. The fast decay of the excited state, tau similar to 12 ps, indicates that diffusion of hot electrons into the bulk is an important mechanism.
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| 14. |
- He, Z Q, et al.
(författare)
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Band structure evolution in InAs overlayers on GaAs(110)
- 1996
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 104, s. 608-614
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Tidskriftsartikel (refereegranskat)abstract
- An angle-resolved photoemission study of MBE grown InAs/GaAs(110) hetero-structures was carried out to investigate the establishment of valence bands as a function of overlayer thickness. The valence band spectra were found to change gradually up to thicknesses well above 10 nm. The data are interpreted in terms of excitations within the overlayer from a combination of substrate and overlayer initial states, the former tailing into the overlayer.
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| 15. |
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| 16. |
- Karlsson, H S, et al.
(författare)
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Electron accumulation at the InAs(110) cleavage surface
- 1998
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 402:1-3, s. 590-594
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Tidskriftsartikel (refereegranskat)abstract
- The InAs(110) cleavage surface is studied by photoelectron spectroscopy based on an amplified short-pulse titanium:sapphire laser system in both probe-only and pump-and-probe modes. The probe-only spectra show that electrons accumulate in the conduction band at the surface as a function of time after cleavage, while the pump-and-probe spectra show a different response from the excited accumulation layer peak when using s- and p-polarized probe pulses. Moreover, no surface photovoltage is detected when the accumulation layer is optically pumped. (C) 1998 Elsevier Science B.V. All rights reserved.
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| 17. |
- Karlsson, H S, et al.
(författare)
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Electron dynamics and accumulation on the InAs(110) surface
- 1998
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 407:1-3, s. L687-L692
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Tidskriftsartikel (refereegranskat)abstract
- Time- and angle-resolved pump-and-probe photoelectron spectroscopy has been used to study the electron dynamics on the InAs(110) surface. Two states, separated by similar to 0.2 eV, can be identified in the conduction band. The time evolution and energy location of these states suggest that they originate from transiently excited levels related to the InAs bulk conduction band. (C) 1998 Elsevier Science B.V. All rights reserved.
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| 18. |
- Karlsson, H S, et al.
(författare)
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System for time- and angle-resolved photoelectron spectroscopy based on an amplified femtosecond titanium:sapphire laser system
- 1996
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 67:10, s. 3610-3615
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Tidskriftsartikel (refereegranskat)abstract
- A system for time- and angle-resolved photoelectron spectroscopy based on an amplified femtosecond titanium:sapphire laser system is described. Using this type of system, angle-resolved photoemission is extended to include the possibility of following the time development of excited electrons at and near a solid surface. Time resolution is accomplished by using pump-and-probe technique and the photoemitted electrons are energy analyzed in a time-of-fight detector. In order to perform photoemission, the near-infrared light from the titanium:sapphire laser is frequency up-converted to the vacuum ultraviolet range. This is accomplished by using the high peak power pulses from the laser system to produce short-wavelength radiation by means of harmonic generation. The system described uses cascaded frequency doubling and tripling, reaching a photon energy close to 10 eV. (C) 1996 American Institute of Physics.
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| 19. |
- Månsson, Martin, et al.
(författare)
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Electronic structure and electron dynamics at the GaSb(001) surface studied by femtosecond pump-and-probe pulsed laser photoemission spectroscopy
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:15, s. 5308-5311
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Tidskriftsartikel (refereegranskat)abstract
- Transiently excited electron states at the GaSb(001) surface have been studied by means of time- and angle-resolved photoemission spectroscopy based on a femtosecond laser system. A normally unpopulated surface electron state has been found at similar to 250 meV above the valence band maximum with a strong confinement at the center of the surface Brillouin zone. The lifetime of transiently excited carriers at the intergap surface states has been found to be similar to 11 ps, associated with rapid carrier diffusion.
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| 20. |
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| 21. |
- Olsson, L O, et al.
(författare)
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Charge accumulation at InAs surfaces
- 1996
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 76:19, s. 3626-3629
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Tidskriftsartikel (refereegranskat)abstract
- Angle-resolved photoelectron spectroscopy has been used to directly prove the existence of a charge accumulation layer at clean InAs surfaces. The formation of an accumulation layer is shown to be a common property of polar InAs surfaces, with the precise surface Fermi level position above the conduction band minimum determined by the surface geometry. The emission from states in the accumulation layer is studied with respect to its photon energy and angular dependence.
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| 22. |
- Qvarford, M, et al.
(författare)
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Photoemission and x-ray absorption study of superconducting and semiconducting Ba1-xKxBiO3 single crystals
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 54:9, s. 6700-6707
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Tidskriftsartikel (refereegranskat)abstract
- Semiconducting Ba0.9K0.1BiO3 and superconducting Ba0.6K0.4BiO3 single crystals cleaved in situ have been studied by core level and valence band photoelectron spectroscopy and O K edge x-ray absorption spectroscopy. It was found that the general shape of the valence band spectrum agrees with the shape predicted by band structure calculations, but the intensity near the Fermi level, was lower in the experimental spectrum as compared to the calculated. The O K edge spectra showed that the metallic phase is not related to the presence of doping inducted O 2p holes. This property of Ba1-xKxBiO3 shows that the semiconductor-metal transition of this system is of a different nature than that of the hole doped cuprate high-T-c superconductors. The core level photoemission spectra of the cations showed a small asymmetry for Ba0.9K0.1BiO3. Corresponding spectra for Ba0.6K0.4BiO3 showed a larger asymmetry resulting in a resolved high binding energy shoulder in the Bi 4f spectrum. The origin of this feature is discussed.
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| 23. |
- TJERNBERG, O, et al.
(författare)
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ANGLE-RESOLVED PHOTOEMISSION ON NIO - ON THE NATURE OF THE VALENCE-BAND
- 1995
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 46:8-10, s. 1215-1218
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Tidskriftsartikel (refereegranskat)abstract
- Angle resolved photoelectron spectroscopy has been performed on the valence band of NiO at the National Swedish Laboratory for Synchrotron Radiation. Normal emission spectra have been recorded for photon energies between 17 and 140 eV in order to study the electronic structure of the valence band. The experimentally determined band structure has been compared with a local density augmented plane wave band structure calculation. Signs of the influence of antiferromagnetic ordering are found and the general agreement between experimental and theoretical oxygen derived bands indicates strong hybridization between Ni 3d and O 2p orbitals.
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| 24. |
- Tjernberg, O, et al.
(författare)
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Influence of magnetic ordering on the NiO valence band
- 1996
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 54:15, s. 10245-10248
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Tidskriftsartikel (refereegranskat)abstract
- The influence of magnetic ordering on the NiO valence band has been studied by angle resolved photoelectron spectroscopy. Measurements have been performed at temperatures above and below the Neel temperature (T-N), as well as at room. temperature. The results show temperature dependence but no significant changes in the valence band structure are detected in connection to the passing of T-N. The reported data suggest that the magnetic phase transition does not influence the valence band structure significantly.
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| 25. |
- Tjernberg, O, et al.
(författare)
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Resonant photoelectron spectroscopy on NiO
- 1996
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 53:15, s. 10372-10376
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Tidskriftsartikel (refereegranskat)abstract
- Resonant photoelectron spectroscopy studies have been performed on the NiO valence band at photon energies corresponding to the Ni 2p, 3p, and O 1s absorption thresholds. Strong resonances are seen in the vicinity of the Ni 2P threshold, which confirm earlier conclusions from the weaker resonances seen at the Ni 3p threshold. No valence-band resonance is observed at the O 1s threshold. The analysis of this data confirms the picture of NiO as a strongly correlated charge-transfer insulator by identifying the highest-lying states as being of mainly 3d(8)L final-state character. The existence of localized excited Ni states, as well as the delocalized nature of the O states, are confirmed. Comparisons with the configuration-interaction model and quasiparticle calculations are also made.
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| 26. |
- Varekamp, P R, et al.
(författare)
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Angle-resolved photoemission spectroscopy of the 1x1 ordered overlayers on iodine-saturated GaAs(001) and InAs(001)
- 1996
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 352, s. 387-390
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Tidskriftsartikel (refereegranskat)abstract
- Angle-resolved valence band photoelectron spectra are collected from 1 X 1 ordered overlayers on I-2-saturated GaAs(001)-4 x 1, -c(2 X 8), and InAs(001)-c(8 x 2). A high-intensity dispersive surface state, located approximately 4.4 eV below the valence band maximum, is observed in each case. The state passes through an open lens in the projected bulk density of states and disperses symmetrically around the surface Brillouin zone edge. For all surfaces studied, the state is stronger when excited with the electric field polarized in the [110], as compared to the <(1)over bar 10>], azimuth. Since the state is independent of the termination of the initial surface, and since iodine bonds primarily to the outermost element, the state must result from delocalization of the electron states in the overlayer, and is not related to bonding with the substrate.
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| 27. |
- Agnarsson, Björn, et al.
(författare)
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Influence of initial surface reconstruction on nitridation of Al2O3 (0001) using low pressure ammonia
- 2007
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:1, s. 013519-
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to investigate the effect of initial surface reconstruction on the nitridation process of Al2O3 (0001). This was done by exposing differently reconstructed sapphire substrates at different temperatures to low pressure ammonia (NH3). Structural and chemical analysis were carried out using low-electron energy diffraction and x-ray photoelectron spectroscopy. The experiments revealed that using low pressure ammonia (P-NH3 < 1 X 10(-5) Torr), no nitridation takes place on (1x1) unreconstructed surfaces. However, when the unreconstructed surface starts to change to a (root 31 x root 31) R +/- 9 degrees reconstructed surface, with increasing substrate temperature, the nitridation becomes successful. When using the initially reconstructed surface, the nitridation is successful even from the lowest temperature used. These results suggest that the initial surface reconstruction has a major effect on the nitridation process. This kinetic behavior has not been reported before, with most nitridation studies mainly focusing on the effect of surface temperature on the resulting surface morphology, rather than the actual kinetics of the process itself.
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| 28. |
- ANDERSEN, JN, et al.
(författare)
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SURFACE RELATED CORE LEVEL SHIFTS FOR THE SI(111)SQUARE-ROOT-3X SQUARE-ROOT-3 - AL SYSTEM
- 1991
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 9:4, s. 2384-2387
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Tidskriftsartikel (refereegranskat)abstract
- The Si(111) square-root 3 x square-root 3:Al reconstruction has been studied by surface sensitive high resolution core level spectroscopy. It is shown that three components are needed to fit the Si 2p spectra. The Al2p emission is found to consist of more than one component and it is argued that this is related to defects in the overlayer.
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| 29. |
- Andersson, C B M, et al.
(författare)
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Bulk and surface electronic structure of InAs(110)
- 1998
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 398:3, s. 395-
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Tidskriftsartikel (refereegranskat)abstract
- The InAs(110) cleavage surface has been investigated by angle-resolved photoelectron spectroscopy. A separation between the In 4d(5/2) bulk component and the valence band maximum of 16.8 eV is found to be consistent with normal emission spectra. Experimental energy band dispersions, E-i(k), for the four bulk valence bands are established along the Sigma-line of the bulk Brillouin zone. A bulk band structure calculation utilizing the augmented plane-wave method is made. The experimental and calculated E-i(k) dispersions are found to be in good agreement with each other. E-i(k(parallel to)) dispersions for two surface-related structures are established along the lines <(Gamma)over bar>-(M) over bar and (Y) over bar-(M) over bar of the surface Brillouin zone. (C) 1998 Elsevier Science B.V.
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| 30. |
- ANDERSSON, CBM, et al.
(författare)
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CORE-LEVEL PHOTOEMISSION FROM (III)-TYPE INAS SURFACES
- 1994
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Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 4:C9, s. 209-212
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Tidskriftsartikel (refereegranskat)abstract
- The InAs(111)2x2 and InAs(($$$) over bar 111)1x1 surfaces have been studied with high resolution core level spectroscopy. For the InAs(($$$) over bar 111)1x1 surface both the In 4d and the As 3d core levels display strong surface core level shifts, while for the InAs(111)2x2 surface only the In 4d level shows a detectable surface shift. The results indicate that the InAs(($$$) over bar 111)1x1 surface is relaxed, with atom layer displacement extending to subsurface layers. Unexpectedly, we find no surface shifted anion core level for the InAs(111)2x2 surface.
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| 31. |
- ANDERSSON, CBM, et al.
(författare)
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SPUTTERED AND ANNEALED INAS(111)OVER-BAR - AN UNRECONSTRUCTED SURFACE
- 1994
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 885-889
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the InAs(111BAR)1 X 1 surface has been investigated by angle resolved photoelectron spectroscopy along the symmetry lines GAMMAKBAR, GAMMAMBAR, and GAMMAMBAR of the surface Brillouin zone. The bulk valence band structure was calculated using a combination of the linear augmented plane-wave method and the relativistic augmented plane-wave method. We have projected the theoretical bulk band structure onto the surface Brillouin zone to separate surface states from surface resonances. Two surface related structures, S1 and S2, have been observed and their E(i)(k(parallel-to)) dispersions are established. Both S1 and S2 show the symmetry of the 1 X 1 surface Brillouin zone, which is consistent with the observed 1 X 1 LEED pattern. We identify S1 as the As-derived dangling bond state, and S2 is associated with the backbonds connecting the As atoms in the surface layer with the underlying In layer.
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| 32. |
- ANDERSSON, CBM, et al.
(författare)
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SURFACE ELECTRONIC-STRUCTURE OF INAS(110)
- 1993
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47:4, s. 2427-2430
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the InAs(I 10) cleavage surface has been studied by angle-resolved photoelectron spectroscopy. The bulk band structure has been calculated utilizing the augmented plane-wave method and then the bulk bands have been projected along the lines GAMMA-XBARBAR and GAMMA-YBARBAR of the surface Brillouin zone (SBZ). Three surface-related structures have been found and their initial state versus k parallel-to dispersion along the line GAMMA-XBARBAR and the line GAMMA-YBARBAR of the SBZ has been determined. The structures are identified as A5, A4, and A3 along GAMMA-XBARBAR and as A5, A4, and C2 along GAMMA-YBARBAR.
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| 33. |
- Babonas, G. J., et al.
(författare)
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Optical properties of Fe-doped silica films on Si
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:15, s. 5391-5394
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Tidskriftsartikel (refereegranskat)abstract
- Optical properties of Fe-doped silica films on Si were investigated by ellipsometric technique in the region 1-5 eV. Samples were produced by sol-gel method. Precursors were prepared by mixing tetraethoxysilane (TEOS) solution in ethanol and water with aqueous solution of Fe-chloride or Fe-acetate. The coating solution was deposited on Si substrates by spin on technique. The size of Fe-containing nanometric-sized particles depended on technology and varied from 20 to 100 nm. Optical response of complex hybrid samples SiO2:Fe/Si was interpreted in a multi-layer model. In the inverse problem, the Maxwell equations were solved by transfer matrix technique. Dielectric function of Fe-doped silica layers was calculated in the model of effective media. Analysis of optical data has shown that various Fe-oxides formed. Experimental data for films obtained from precursors with Fe-acetate and annealed in hydrogen were well described by the model calculations taking into account a small contribution 1-5% of metal Fe imbedded in silica. The Fe/Fe-O contribution to optical response increased for samples grown from FeCl3-precursor. Ellipsometric data for Fe-doped silica films on Si were interpreted taking into account the structural AFM studies as well as the results of magnetic measurements.
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| 34. |
- Bergstrand, Martin, 1977-, et al.
(författare)
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A semi-mechanistic model for characterization of regional absorption properties and prospective prediction of plasma concentrations following administration of new modified release formulations
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Methods to study in vivo gastro intestinal (GI) transit and/or regional absorption of pharmaceuticals are available and increasingly used in drug development. A modelling approach to utilize the information generated in such studies for prospective predictions of absorption from newly developed modified release formulations was outlined and tested for the investigational drug AZD0837. This work was a natural extension to the companion article “A semi-mechanistic model to link in vitro and in vivo drug release for modified release formulations”. The drug release model governed the amount of substance released in distinct GI regions over time. GI distribution of released drug substance, region specific rate and extent of absorption and the influence of concomitant food intake were estimated with the model. The model was informed by data from a magnetic marker monitoring study and an intubation study with local administration in colon. Disposition estimates were further supported by observations following administration of oral solution and intravenous infusion of AZD0837. Distinctly different absorption properties were characterized for different GI regions. Bioavailability over the gut-wall was estimated to be high for substance released in the stomach and absorbed in duodenum (70%) compared to substance released and absorbed in the small intestine (25%). Bioavailability was once again higher in colon (70%) but on the other hand considerably slower than in the earlier parts of the GI tract. The established model was largely successful in predicting plasma concentration following administration of three newly developed formulations for which no clinical data had been applied during model building.
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| 35. |
- Bergstrand, Martin, 1977-, et al.
(författare)
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A semi-mechanistic model to link in vitro and in vivo drug release for modified release formulations
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In vivo prediction of drug release based on in vitro experiments is important for the development of new modified release (MR) formulations. Most efforts to improve such predictions have focused on altering the in vitro experiments to more resemble the in vivo conditions. A novel approach is evaluated in the present article where a computer model is established and used to link results from standard static in vitro experiment to in vivo predictions. A nonlinear mixed-effects model describing the in vitro drug release for 6 closely related hydrophilic matrix based MR formulations across different experimental conditions (pH, rotation speed and ionic strength) was developed. This model was applied to in vivo observations of drug release and tablet gastro intestinal (GI) position assessed with Magnetic Marker Monitoring (MMM). By combining the MMM observations with literature information on pH and ionic strength along the GI tract, the mechanical stress in different parts of the GI tract could be estimated in units equivalent to rotation speed in the in vitro set-up (USP 2 apparatus). The mechanical stress in the upper stomach was estimated to be 94 rpm and 134 rpm in the lower stomach. For the small intestine and colon the estimates of mechanical stress was 93 and 38 rpm respectively. Predictions of in vivo drug release including expected between subject/tablet variability could be made for other newly developed formulations based on the drug release model combined with a model describing tablet GI transit. This exemplifies a modeling approach that can be utilized to predict in vivo behavior from standard in vitro experiments and support formulation development and quality control of MR formulations.
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| 36. |
- Bergstrand, Martin, 1977-, et al.
(författare)
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A semi-mechanistic modeling strategy for characterization of regional absorption properties and prospective prediction of plasma concentrations following administration of new modified release formulations
- 2012
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Ingår i: Pharmaceutical research. - : Springer Science+Business Media B.V.. - 0724-8741 .- 1573-904X. ; 29:2, s. 574-584
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE To outline and test a new modeling approach for prospective predictions of absorption from newly developed modified release formulations based on in vivo studies of gastro intestinal (GI) transit, drug release and regional absorption for the investigational drug AZD0837. METHODS This work was a natural extension to the companion article "A semi-mechanistic model to link in vitro and in vivo drug release for modified release formulations". The drug release model governed the amount of substance released in distinct GI regions over time. GI distribution of released drug substance, region specific rate and extent of absorption and the influence of food intake were estimated. The model was informed by magnetic marker monitoring data and data from an intubation study with local administration in colon. RESULTS Distinctly different absorption properties were characterized for different GI regions. Bioavailability over the gut-wall was estimated to be high in duodenum (70%) compared to the small intestine (25%). Colon was primarily characterized by a very slow rate of absorption. CONCLUSIONS The established model was largely successful in predicting plasma concentration following administration of three newly developed formulations for which no clinical data had been applied during model building.
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| 37. |
- Bergstrand, Martin, 1977-, et al.
(författare)
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A Semi-mechanistic Modeling Strategy to Link In Vitro and In Vivo Drug Release for Modified Release Formulations
- 2012
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Ingår i: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 29:3, s. 695-706
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To develop a semi-mechanistic model linking in vitro to in vivo drug release. METHODS: A nonlinear mixed-effects model describing the in vitro drug release for 6 hydrophilic matrix based modified release formulations across different experimental conditions (pH, rotation speed and ionic strength) was developed. It was applied to in vivo observations of drug release and tablet gastro intestinal (GI) position assessed with magnetic marker monitoring (MMM). By combining the MMM observations with literature information on pH and ionic strength along the GI tract, the mechanical stress in different parts of the GI tract could be estimated in units equivalent to rotation speed in the in vitro USP 2 apparatus. RESULTS: The mechanical stress in the upper and lower stomach was estimated to 94 and 134 rpm, respectively. For the small intestine and colon the estimates of mechanical stress was 93 and 38 rpm. Predictions of in vivo drug release including between subject/tablet variability was made for other newly developed formulations based on the drug release model and a model describing tablet GI transit. CONCLUSION: The paper outlines a modeling approach for predicting in vivo behavior from standard in vitro experiments and support formulation development and quality control.
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| 38. |
- Bjorkqvist, M, et al.
(författare)
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Nitride formation and dangling-bond passivation on Si(111)-(7x7) with NH3
- 1997
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 394:1-3, s. L155-L161
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Tidskriftsartikel (refereegranskat)abstract
- Thermal nitridation of the Si(111)-(7 x 7) reconstructed surface with ammonia has been investigated using scanning tunneling microscopy (STM). True nitride formation in the form of ring-like structures as in stoichiometric silicon nitride (Si3N4) was observed at imperfections on the surface, which otherwise preserved the characteristics of the (7 x 7) reconstruction. However, the ratio of reacted adatoms in the reconstruction never exceeded similar to 50%, indicative of a frustrated saturation behavior for the adatom dangling bonds in the Si(111)-(7 x 7)-NH3 reaction system. (C) 1997 Elsevier Science B.V.
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| 39. |
- Bååthe, Sofie, et al.
(författare)
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Population pharmacokinetics of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, in atrial fibrillation patients receiving long-term anticoagulation therapy
- 2006
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 45:8, s. 803-819
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ximelagatran is an oral direct thrombin inhibitor for the prevention of thromboembolic disease. After oral administration, ximelagatran is rapidly absorbed and bioconverted to its active form, melagatran. Objective: To characterise the pharmacokinetics of melagatran in patients with nonvalvular atrial fibrillation (NVAF) receiving long-term treatment for prevention of stroke and systemic embolic events. Methods: A population pharmacokinetic model was developed based on data from three phase 11 studies (1177 plasma concentration observations in 167 patients, treated for up to 18 months) and confirmed by including data from two phase III studies (8702 plasma concentration observations in 3188 patients, treated for up to 24 months). The impact of individualised dosing on pharmacokinetic variability was evaluated by simulations of melagatran concentrations based on the pharmacokinetic model. Results: Melagatran pharmacokinetics were consistent across the studied doses and duration of treatment, and were described by a one-compartment model with first-order absorption and elimination. Clearance of melagatran was correlated to creatinine clearance, which was the most important predictor of melagatran exposure (explained 54% of interpatient variance in clearance). Total variability (coefficient of variation) in exposure was 45%; intraindividual variability in exposure was 23%. Concomitant medication with the most common long-term used drugs in the study population had no relevant influence on melagatran pharmacokinetics. Simulations suggested that dose adjustment based on renal function or trough plasma concentration had a minor effect on overall pharmacokinetic variability and the number of patients with high melagatran exposure. Conclusion: The pharmacokinetics of melagatran in NVAF patients were predictable, and consistent with results from previously studied patient populations. Dose individualisation was predicted to have a low impact on pharmacokinetic variability, supporting the use of a fixed-dose regimen of ximelagatran for long-term anticoagulant therapy in the majority of NVAF patients.
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| 40. |
- Carlsson, Arne, et al.
(författare)
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Emissionsmodell för tunnlar
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Tunnels for road and street traffic become increasingly important for transport provisions, primarily in large cities. Currently, there are in Stockholm and Gothenburg high-volume tunnels in the primary road network. In addition, many new tunnels will soon be finalised or are planned both in Stockholm and Gothenburg. The exhaust emissions in road tunnels may not exceed certain limits. Road tunnels are equipped with ventilation systems to make sure that limits for air quality are not exceeded, primarily emissions of NO2. The ventilation systems are dimensioned using data on maximum expected emissions per unit of time. VTI has obtained a commission from the Swedish National Road Administration (SNRA) to develop a model for calculation of exhaust emissions in tunnels, which in addition shall take into account oversaturated conditions. Currently, SNRA has no satisfactory model for calculations at hourly level. The objective of the development effort has been to formulate a calculation model for travel speeds and emissions in motorway tunnels, to be used when tunnel ventilation systems are dimensioned. For a complete structure, the model shall provide individual tunnel tube emission data for hourly traffic, split upon homogenous - from the viewpoint of traffic engineering - road links and ventilation segments. This report describes the results of the development project for calculation of emissions in tunnels. The completed model comprises two parts, one for calculation of speed and corresponding hourly flow at given demand level and one for calculation of emissions, using hourly flows and speed as input data. For each part, there is a computer program with user manual. Test runs of the model for some basic typical tunnel cases, has been carried out to illustrate the results of the total model. The total emissions of NOx (kg/km) as a function of traffic flow have been calculated for different degree of traffic load. In addition, the model has been validated by comparisons of calculated NOx values from the model with measured NOx values in three different tunnels: the Gnistäng tunnel and the Tingstad tunnel in Gothenburg and the Southern Route tunnel in Stockholm.
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| 41. |
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| 42. |
- CHAKARIAN, V, et al.
(författare)
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THE ADSORPTION OF I2 ON SI(111)-7X7 STUDIED BY SOFT-X-RAY PHOTOEMISSION
- 1993
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 296:3, s. 383-392
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption Of I2 on Si(111)-7 x 7 at room temperature is studied with soft X-ray photoelectron spectroscopy. I2 adsorbs dissociatively, forming a mixture of SiI, SiI2 and SiI3 moieties, of which SiI dominates. The Fermi level is pinned near mid-gap, moving slightly towards the conduction band as the I coverage increases. The surface work function increases monotonically with I coverage. The I 4d core-level displays a single chemical state, which decreases in binding energy with increasing coverage. Analysis of the Si 2p core-level spectra shows that the adsorption proceeds first by attachment of I to the dangling bonds of the 7 x 7 unit cell and that, at saturation, 1.57 +/- 0.05 ML of I atoms are adsorbed in 1.10 +/- 0.02 ML of SiI(x) groups. These results indicate that substrate Si-Si bonds are broken by reaction with I2. The total I coverage is limited, however, by the availability Of surface dangling bonds that are required to initiate the dissociation Of I2 molecules.
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| 43. |
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| 44. |
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| 45. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 46. |
- Cullberg, Marie, 1958-
(författare)
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Direct Thrombin Inhibitors in Treatment and Prevention of Venous Thromboembolism: Dose – Concentration – Response Relationships
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For prevention and treatment of thrombotic diseases with an anticoagulant drug it is important that an adequate dose is given to avoid occurrence or recurrence of thrombosis, without increasing the risk of bleeding and other adverse events to unacceptable levels. The aim of this thesis was to develop mathematical models that describe the dose-concentration (pharmacokinetic) and concentration-response (pharmacodynamic) relationships of direct thrombin inhibitors, in order to estimate optimal dosages for treatment and long-term secondary prevention of venous thromboembolism (VTE).Population pharmacokinetic-pharmacodynamic models were developed, based on data from clinical investigations in healthy volunteers and patients receiving intravenous inogatran, subcutaneous melagatran and/or its oral prodrug ximelagatran. The benefit-risk profiles of different ximelagatran dosages were estimated using clinical utility functions. These functions were based on the probabilities and fatal consequences of thrombosis, bleeding and elevation of the hepatic enzyme alanine aminotransferase (ALAT).The studies demonstrate that the pharmacokinetics of melagatran and ximelagatran were predictable and well correlated to renal function. The coagulation marker, activated partial thromboplastin time (APTT), increased non-linearly with increasing thrombin inhibitor plasma concentration. Overall, the systemic melagatran exposure (AUC) and APTT were similarly predictive of thrombosis and bleedings. The identified relationship between the risk of ALAT-elevation and melagatran AUC suggests that the incidence approaches a maximum at high exposures. The estimated clinical utility was favourable compared to placebo in the overall study population and in special subgroups of patients following fixed dosing of ximelagatran for long-term secondary prevention of VTE. Individualized dosing was predicted to add limited clinical benefit in this indication.The models developed can be used to support the studied dosage and for selection of alternative dosing strategies that may improve the clinical outcome of ximelagatran treatment. In addition, the models may be extrapolated to aid the dose selection in clinical trials with other direct thrombin inhibitors.
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| 47. |
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| 48. |
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| 49. |
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| 50. |
- Davila, Maria E., et al.
(författare)
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Perturbation of Ge(111) and Si(111)root 3 alpha-Sn surfaces by adsorption of dopants
- 2006
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 600:16, s. 3154-3159
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Tidskriftsartikel (refereegranskat)abstract
- We test the response of the root 3 x root 3 alpha reconstructions formed by 1/3 monolayer of tin adatoms on silicon and germanium (111) surfaces upon doping with electrons or holes, using potassium or iodine as probes/perturbers of the initial electronic structures. From detailed synchrotron radiation photoelectron spectroscopy studies we show that doping with either electrons or holes plays a complimentary role on the Si and Ge surfaces and, especially, leads to complete conversion of the Sn 4d two-component spectra into single line shapes. We find that the low binding energy component of the Sn core level for both Si and Ge surfaces corresponds to Sn adatoms with higher electronic charge, than the Sn adatoms that contribute to the core level high binding energy signal. This could be analyzed as Sn adatoms with different valence state.
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