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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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| 3. |
- Steffen, L M, et al.
(författare)
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Serum phospholipid and cholesteryl ester fatty acids and estimated desaturase activities are related to overweight and cardiovascular risk factors in adolescents
- 2008
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 32:8, s. 1297-1304
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Tidskriftsartikel (refereegranskat)abstract
- Aim/hypothesis: The objective of this study was to describe the relation of serum fatty acids and desaturase activity (DA) to overweight, insulin sensitivity and cardiovascular disease (CVD) risk factors in adolescents. Methods: The relations of % serum phospholipid (PL) and cholesteryl ester (CE) fatty acids and estimated DA with CVD risk factors were examined in 264 adolescents (average age 15 years). Fatty acids were determined by gas liquid chromotography. Surrogate measures of DA were expressed as ratios of serum fatty acids: Delta 9 DA 16: 0/16: 1, Delta 6 DA 20: 3, n6/18: 2, n6 (PL) or 18: 3, n6/18: 2, n6 (CE), and Delta 5 DA 20: 4, n6/20: 3, n6. Spearman partial correlations of fatty acids (%) and DA ratios with CVD risk factors were reported, adjusting for age, sex, race, Tanner stage, energy intake and physical activity. Results: Overweight adolescents compared to normal weight had more adverse levels of CVD risk factors, composition of PL and CE fatty acids in serum, and D6 DA and D5 DA ratios. Linoleic acid was inversely related to body mass index (BMI), waist circumference and triglycerides (P < ;= 0.01). Dihomo-gamma-linolenic acid was positively related to BMI, waist, insulin, and triglycerides, and inversely related to high-density lipoprotein-cholesterol levels (P < ;= 0.01). D6 DA was adversely associated with most of the risk factors (P < ;= 0.01), whereas triglycerides and fasting insulin were beneficially related to D5 DA (P < ;= 0.01). Conclusion: These findings support those observed in adults, that factors, such as type of dietary fat, physical activity, and obesity, may influence fatty acid metabolism and are important in the development of adverse CVD risk factors as early as adolescence.
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