| 1. |
- 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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| 2. |
- Paul, E. S., et al.
(författare)
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Loss of collectivity in the transitional Er-156 nucleus at high spin
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 79:4
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Tidskriftsartikel (refereegranskat)abstract
- The Cd-114(Ca-48, 6n gamma) reaction at 215 MeV has been investigated using the Gammasphere spectrometer to study the high-spin structure of the nucleus Er-156(68)88. Many new transitions have been established along with 68 definitive spin-parity level assignments from a high-fold angular-distribution analysis. In addition, absolute B(M 1) and B(E 1) strengths have been inferred from measured gamma-ray branching ratios. Strong B(E 1) strength (10(-3) W.u.) is discussed in terms of possible octupole collectivity at low spin. At high spin, this nucleus undergoes a Coriolis-induced shape transition from a prolate state of collective rotation to a noncollective, triaxial-oblate configuration. The yrast positive-parity structure ultimately terminates in an energetically favored oblate state at I-pi = 42(+). Several weak high-energy gamma-ray transitions have been discovered that feed this favored state. State-of-the-art cranked Nilsson-Strutinsky calculations are used to interpret the high-spin behavior of Er-156 and comparisons are made with other N = 88 isotones.
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| 3. |
- Riley, M. A., et al.
(författare)
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Strongly Deformed Nuclear Shapes at Ultra-High Spin and Shape Coexistence in N\sim 90 Nuclei
- 2009
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Ingår i: Acta Physica Polonica B. - 0587-4254. ; 40:3, s. 513-522
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Tidskriftsartikel (refereegranskat)abstract
- The N similar to 90 region of the nuclear chart has featured prominently as the spectroscopy of nuclei at extreme spin has progressed. This talk will present recent discoveries from investigations of high spin behavior in the N similar to 90 Er, Tm and Yb nuclei utilizing the Gammasphere gamma-ray spectrometer. In particular it will include discussion of the beautiful shape evolution and coexistence observed in these nuclei along with the identification of a remarkable new family of band structures. The latter are very weakly populated rotational sequences with high moment of inertia that bypass the classic terminating configurations near spin 40-50 (h) over bar, marking a return to collectivity that extends discrete gamma-ray spectroscopy to well over 60 (h) over bar. Establishing the nature of the yrast states in these nuclei beyond the oblate band-termination states has been a major goal for the past two decades. Cranking calculations suggest that these new structures most likely represent stable triaxial strongly deformed bands that lie in a valley of favored shell energy in deformation and particle-number space.
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| 4. |
- Burgess, Selena G, et al.
(författare)
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Probing the dynamic interface between trimethylamine dehydrogenase (TMADH) and electron transferring flavoprotein (ETF) in the TMADH—2ETF complex: role of the Arg-alpha237 (ETF) and Tyr-442 (TMADH) residue pair.
- 2008
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 47:18, s. 5168-5181
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Tidskriftsartikel (refereegranskat)abstract
- We have used multiple solution state techniques and crystallographic analysis to investigate the importance of a putative transient interaction formed between Arg-alpha237 in electron transferring flavoprotein (ETF) and Tyr-442 in trimethylamine dehydrogenase (TMADH) in complex assembly, electron transfer, and structural imprinting of ETF by TMADH. We have isolated four mutant forms of ETF altered in the identity of the residue at position 237 (alphaR237A, alphaR237K, alphaR237C, and alphaR237E) and with each form studied electron transfer from TMADH to ETF, investigated the reduction potentials of the bound ETF cofactor, and analyzed complex formation. We show that mutation of Arg-alpha237 substantially destabilizes the semiquinone couple of the bound FAD and impedes electron transfer from TMADH to ETF. Crystallographic structures of the mutant ETF proteins indicate that mutation does not perturb the overall structure of ETF, but leads to disruption of an electrostatic network at an ETF domain boundary that likely affects the dynamic properties of ETF in the crystal and in solution. We show that Arg-alpha237 is required for TMADH to structurally imprint the as-purified semiquinone form of wild-type ETF and that the ability of TMADH to facilitate this structural reorganization is lost following (i) redox cycling of ETF, or simple conversion to the oxidized form, and (ii) mutagenesis of Arg-alpha237. We discuss this result in light of recent apparent conflict in the literature relating to the structural imprinting of wild-type ETF. Our studies support a mechanism of electron transfer by conformational sampling as advanced from our previous analysis of the crystal structure of the TMADH-2ETF complex [Leys, D. , Basran, J. , Sutcliffe, M. J., and Scrutton, N. S. (2003) Nature Struct. Biol. 10, 219-225] and point to a key role for the Tyr-442 (TMADH) and Arg-alpha237 (ETF) residue pair in transiently stabilizing productive electron transfer configurations. Our work also points to the importance of Arg-alpha237 in controlling the thermodynamics of electron transfer, the dynamics of ETF, and the protection of reducing equivalents following disassembly of the TMADH-2ETF complex.
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| 5. |
- Ollier, J., et al.
(författare)
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Ultrahigh-spin spectroscopy of Er-159,Er-160: Observation of triaxial strongly deformed structures
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
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Tidskriftsartikel (refereegranskat)abstract
- Three weakly populated high-spin rotational bands associated with the gamma decay of Er-159 and Er-160 were observed in fusion-evaporation reactions involving a beam of Ca-48 at an energy of 215 MeV incident on a Cd-116 target. The gamma decays were detected using the highly efficient Gammasphere spectrometer. The discovery of these bands, which extend discrete-line spectroscopy in these nuclei to ultrahigh spin of similar to 60h, is consistent with recent observations of high-spin collective structures in isotopes of Er, Yb, and Tm around N=90. Cranked Nilsson-Strutinsky calculations suggest that these bands may arise from well-deformed triaxial configurations with either positive or negative gamma deformation.
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| 6. |
- Seale, A N, et al.
(författare)
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Pulmonary vein stenosis: the UK, Ireland and Sweden collaborative study.
- 2009
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Ingår i: Heart (British Cardiac Society). - : BMJ. - 1468-201X .- 1355-6037. ; 95:23, s. 1944-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To describe clinical features, morphology, management and outcome of pulmonary vein stenosis (PVS) in childhood. DESIGN AND SETTING: Retrospective international collaborative study involving 19 paediatric cardiology centres in the UK, Ireland and Sweden. PATIENTS: Cases of PVS presenting between 1 January 1995 and 31 December 2004 were identified. Cases where pulmonary veins connected to a morphological left atrium were included. Functionally univentricular hearts and total anomalous pulmonary venous connection were excluded. All available data and imaging were reviewed. RESULTS: 58 cases were identified. In 22 cases (38%) there was premature delivery. 46 (79%) had associated cardiac lesions; 16 (28%) had undergone previous cardiac surgery before PVS diagnosis. 16 children (28%) had a syndrome or significant extracardiac abnormality. 36 presented with unilateral disease of which 86% was on the left. Where there was adequate sequential imaging, disease progression was shown with discrete stenosis leading to diffusely small pulmonary veins. Collateral vessels often developed. 13 patients had no intervention. Initial intervention was by catheter in 17 and surgery in 28. Overall 3-year survival was 49% (95% CI 35% to 63%) with patients undergoing initial surgical intervention having greater freedom from death or re-intervention (hazard ratio 0.44, 95% CI 0.2 to 0.99, p = 0.023). CONCLUSIONS: PVS is a complex disease of uncertain cause and frequently associated with prematurity. Early intervention may be indicated to deter irreversible secondary changes.
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