| 1. |
- Schael, S, et al.
(författare)
-
Precision electroweak measurements on the Z resonance
- 2006
-
Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
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.
|
|
| 2. |
- Hou, X. M., et al.
(författare)
-
Oxidation kinetics of aluminum nitride at different oxidizing atmosphere
- 2008
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 465:1-2, s. 90-96
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work, the oxidation kinetics of AlN powder was investigated by using thermogravimetric analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experiments were carried out both in isothermal as well as non-isothermal modes under two different oxidizing atmospheres. The results showed that the oxidation reaction started at around 1100 K and the rate increased significantly beyond 1273 K forming porous aluminum oxide as the reaction product. The oxidation rate was affected by temperature and oxygen partial pressure. A distinct change in the oxidation mechanism was noticed in the temperature range 1533-1543 K which is attributed to the phase transformation in oxidation product, viz. alumina. Diffusion is the controlling step during the oxidation process. Based on the experimental data, a new model for predicting the oxidation process of AlN powder had been developed, which offered an analytic form expressing the oxidation weight increment as a function of time, temperature and oxygen partial pressure. The application of this new model to this system demonstrated that this model could be used to describe the oxidation behavior of AlN powder.
|
|
| 3. |
- Learmonth, T., et al.
(författare)
-
Observation of multiple Zhang-Rice excitations in a correlated solid : Resonant inelastic X-ray scattering study of Li2CuO2
- 2007
-
Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 79:4, s. 47012-
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple Zhang-Rice type spectral features have been observed in resonant inelastic X-ray scattering (RIXS) from the quasi -one-dimensional cuprate charge transfer insulator Li2CuO2. The first feature appears at constant emission energy, and is associated with a Zhang-Rice singlet final state. The second is an interplaquette charge transfer excitation that results in a novel triplet Zhang-Rice -type final state. It is accompanied by the presence of a O 2p nonbonding to upper Hubbard band excitation at an energy close to that of a calculated triplet charge transfer Zhang-Rice -type excitation. The site selectivity and polarization rules associated with RIXS allows these two excitations to be distinguished.
|
|
| 4. |
- Chou, M-Y, et al.
(författare)
-
Oxidation-specific epitopes are important targets of innate immunity.
- 2008
-
Ingår i: Journal of internal medicine. - : Wiley. - 1365-2796 .- 0954-6820. ; 263:5, s. 479-88
-
Forskningsöversikt (refereegranskat)abstract
- During the oxidation of LDL, a central pathophysiological component of atherogenesis, a wide variety of chemical and physical changes occur leading to the generation of oxidation-specific neoepitopes. These epitopes are not only immunogenic, leading to adaptive humoral responses, but are also a prominent target of multiple arcs of innate immunity. The pattern recognition receptors (PRRs) of innate immunity are germ line encoded, conserved by natural selection, and bind to pathogen-associated molecular patterns (PAMPs) common on multiple structures. However, it is not intuitive as to why they should recognize oxidation-specific neoepitopes. Yet it is clear that multiple macrophage scavenger receptors, which are classic PRRs, recognize oxidation-specific epitopes, such as those found on oxidized LDL (OxLDL). Other innate proteins, such as C-reactive protein, also bind to OxLDL. Natural antibodies (NAbs), the humoral arc of innate immunity, provide a nonredundant role in the first line of defence against pathogens, but are also believed to provide important homeostatic house-keeping functions against self-antigens. Our work demonstrates that oxidation-specific epitopes, as found on OxLDL, are a major target of NAbs. In this review, we will discuss the specific example of the prototypic NAb T15/E06, which is increased in atherosclerotic mice and mediates atheroprotection, and discuss the potential role of NAbs in atherogenesis, and in inflammation in general. We also review data that oxidation-specific epitopes are generated whenever cells undergo programmed cell death, forming a common set of PAMPs recognized by oxidation-specific PRRs on macrophages, NAbs and innate proteins. We present the hypothesis that oxidation-specific epitopes on apoptotic cells exerted evolutionary pressure for the conservation of these PRRs and also serve to maintain the expansion of a substantial proportion of NAbs directed to these stress-induced self-antigens.
|
|
| 5. |
- Sterneland, Therese
(författare)
-
Thermodynamic Study of Co-Cr and C-Co-Cr Systems
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An experimental investigation of the binary system Co-Cr and the ternary system C-Co-Cr has been carried out in the present thesis. The experimental strategy adopted for the binary system was to measure the thermodynamic activities of Cr, the molar heat capacity as function of time, the phase transformation temperatures with corresponding enthalpies, the Curie transition temperature as well as melting temperatures with corresponding enthalpies. In the ternary system the strategy was to determine the solubility of Co in the Cr7C3 phase as well as the C and Cr contents in the Co rich (fcc) binder phase. The experimental results were compared with atomistic simulations of the solubility of Co in the Cr7C3 phase. Solid state galvanic cell measurements were conducted with both ZrO2-7.5 mol % CaO and CaF2 as the solid electrolyte. In view of possible errors in the measurements with ZrO2-7.5 mol % CaO, as a result of electronic contributions to the conduction of the solid electrolyte, new measurements were conducted with CaF2 as the solid electrolyte. The results indicated that the measured EMF values showed trends which were contrary to the thermodynamic behaviour expected from phase diagram considerations. It was concluded that further detailed experimentation was necessary in order to throw more light on the thermodynamic behaviour of the Co-Cr system. Two different series of DSC measurements were conducted, i.e. one in an atmosphere of pure hydrogen and another in pure argon. In the first investigation, conducted in an atmosphere of pure hydrogen in the temperature interval 318-1660 K, evidence was obtained for the existence of a phase transformation around 900 K in the compositional range 20.7-67.1 wt.% Cr. No indications of such a phase transformation had earlier been seen. In the second investigation, conducted in an atmosphere of pure argon in the temperature interval 298-1823 K, special attention was given to alloys in the Co rich corner of the phase diagram, i.e. 0-10 wt.% Cr. This investigation verified earlier findings of a phase transformations around 900 K in the compositional range 20.7-67.4 wt.% Cr. The magnetic transition temperatures for alloys low in Cr content were also obtained. With the use of the DTA technique the melting temperatures with corresponding enthalpy values for alloys in the compositional range 0.9-7.7 wt.% Cr were obtained. The three-phase triangle fcc+Cr7C3+graphite was investigated at 1373 K, 1423 K and 1473 K. The obtained results showed that the solubility of cobalt in the Cr7C3 phase was significantly higher than previously predicted by thermodynamic calculations.
|
|
| 6. |
- Wei, P K, et al.
(författare)
-
Beaming effect of optical near-field in multiple metallic slits with nanometric linewidth and micrometer pitch
- 2005
-
Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 253:1-3, s. 198-204
-
Tidskriftsartikel (refereegranskat)abstract
- The beaming effect and interference patterns on the exit surface of multiple nano metallic slits with micrometer pitch were observed by scanning near-field optical microscopy. The near-field light intensity for multiple slits had a longer propagation tail and a smaller diverging angle as compared to that in a single slit. From finite-difference time-domain calculations, we verify that these fringe patterns come from the interference effect of longitudinal electric field, which is propagating along the surface. The beaming light in the slit openings is also attributed to the addition of longitudinal fields.
|
|
