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- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 5. |
- Boukhvalov, D. W., et al.
(författare)
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Electronic structure of a Mn-12 molecular magnet : Theory and experiment
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:1, s. 014419-
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Tidskriftsartikel (refereegranskat)abstract
- We used site-selective and element-specific resonant inelastic x-ray scattering (RIXS) to study the electronic structure and the electron interaction effects in the molecular magnet [Mn12O12(CH3COO)(16)(H2O)(4)]center dot 2CH(3)COOH center dot 4H(2)O, and compared the experimental data with the results of local spin density approximation +U electron structure calculations which include the on-site Coulomb interactions. We found a good agreement between theory and experiment for the Coulomb repulsion parameter U = 4 eV. In particular, the p-d band separation of 1.8 eV has been found from the RIXS spectra, which is in accordance with the calculations. Similarly, the positions of the peaks in the XPS spectra agree with the calculated densities of p and d states. Using the results of the electronic structure calculations, we determined the intramolecular exchange parameters, and used them for diagonalization of the Mn-12 spin Hamiltonian. The calculated exchanges gave the correct ground state with the total spin S = 10.
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| 6. |
- Enculecu, I., et al.
(författare)
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Current perpendicular to plane single-nanowire GMR sensor
- 2007
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 86:1, s. 43-47
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Tidskriftsartikel (refereegranskat)abstract
- By electrochemical deposition in a single nanopore membrane we fabricate Cu/Co layered single nanowires, that exhibit up to 10% magnetoresistance at room temperature. Single nanopore membranes are prepared by irradiating polycarbonate membranes with exactly one swift heavy ion, and by subsequent chemical etching of the single ion track. Both dc and pulsed electrodeposition of single wires consisting of Cu-Co alloy and Cu/Co multilayers respectively, are performed from a bath containing the two metal ions. By sputtering a gold electrode on the upper membrane surface, the single nanowire embedded in the flexible polymer foil is reliably contacted. While alloy wires exhibit anisotropic magnetoresistance (AMR), multilayer wires display current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) behavior. This demonstrates that both the fabrication and contacting methods are very suitable for the investigation of transport properties, without the necessity of lithographic processes and without manipulation of the nanowires. In addition, the method opens up many new possibilities for single nanowire-based sensors.
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| 7. |
- Galakhov, V. R., et al.
(författare)
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Electronic structure and x-ray spectra of defective oxides LixCoO2
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:4, s. 045120-
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption, resonant x-ray emission, and x-ray photoelectron spectra of the valence band and core levels have been measured for LixCoO2 (0.6 <= x <= 1.0). Resonant O K alpha x-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between unoccupied and occupied Co 3d states. On the basis of measurements of Co 3s x-ray photoelectron and Co 2p and O 1s x-ray absorption spectra it was established that in defective cobaltites the electronic holes are localized mainly in O 2p states. Evidence of phase separation in LixCoO2 has been found.
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- Koppe, Cordelia, et al.
(författare)
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Reduction of arteriosclerotic nanoplaque formation and size by n-3 fatty acids in patients after valvular defect operation
- 2009
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Ingår i: Forschende Komplementärmedizin. - : S. Karger AG. - 1424-7364 .- 1424-7372. ; 16:4, s. 237-245
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/METHODS: Coating a silica surface with the isolated lipoprotein receptor heparan sulfate proteoglycan (HS-PG) from arterial endothelium and vascular matrices, we could observe the very earliest stages of arteriosclerotic plaque development by ellipsometric techniques in vitro (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients applying their native blood lipoprotein fractions. RESULTS: In 7 patients who had undergone a valvular defect operation, the reduction of arteriosclerotic nanoplaque formation in normal Krebs solution amounted to 6.1 +/- 2.3% (p < 0.0156) and of nanoplaque size to 37.5 +/- 13.2% (p < 0.0312), respectively, after a 3-month therapy with n-3 fatty acids (3 ..3 g daily, Ameu 500 mg). Additionally, the quotient oxLDL/LDL was lowered by 6.8 +/- 2.1% (p < 0.0166), the MDA concentration remained unchanged and the lipoprotein(a) concentration decreased by 15.8 +/- 5.6% (p < 0.0469) in the patients' blood. The concentration of the nanoplaque promoting particles VLDL and total triglycerides was diminished by 34.1 +/- 11.6% (p < 0.0469) and 26.7 +/- 10.8% (p < 0.0156), respectively. Furthermore, the ratio of the strongly atherogenic small dense to the total LDL cholesterol (LDL5+LDL6)/LDLtot decreased by 9.9 +/- 3.0% (p < 0.0174). CONCLUSIONS: A combinatorial regression analysis revealed a basis for a mechanistic explanation of nanoplaque reduction under n-3 fatty acid treatment. This effect was possibly due to the beneficial changes in lipid concentrations and an attenuation of the risk factors oxLDL/LDL and (LDL5+LDL6)/LDLtot.
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