| 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. |
- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 3. |
- Iacopetta, B, et al.
(författare)
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Functional categories of TP53 mutation in colorectal cancer: results of an International Collaborative Study.
- 2006
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Ingår i: Annals of oncology : official journal of the European Society for Medical Oncology / ESMO. - : Elsevier BV. - 0923-7534. ; 17:5, s. 842-7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Loss of TP53 function through gene mutation is a critical event in the development and progression of many tumour types including colorectal cancer (CRC). In vitro studies have found considerable heterogeneity amongst different TP53 mutants in terms of their transactivating abilities. The aim of this work was to evaluate whether TP53 mutations classified as functionally inactive (< or=20% of wildtype transactivation ability) had different prognostic and predictive values in CRC compared with mutations that retained significant activity. MATERIALS AND METHODS: TP53 mutations within a large, international database of CRC (n = 3583) were classified according to functional status for transactivation. RESULTS: Inactive TP53 mutations were found in 29% of all CRCs and were more frequent in rectal (32%) than proximal colon (22%) tumours (P < 0.001). Higher frequencies of inactive TP53 mutations were also seen in advanced stage tumours (P = 0.0003) and in tumours with the poor prognostic features of vascular (P = 0.006) and lymphatic invasion (P = 0.002). Inactive TP53 mutations were associated with significantly worse outcome only in patients with Dukes' stage D tumours (RR = 1.71, 95%CI 1.25-2.33, P < 0.001). Patients with Dukes' C stage tumours appeared to gain a survival benefit from 5-fluorouracil-based chemotherapy regardless of TP53 functional status for transactivation ability. CONCLUSIONS: Mutations that inactivate the transactivational ability of TP53 are more frequent in advanced CRC and are associated with worse prognosis in this stage of disease.
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| 7. |
- Bryzgalova, G, et al.
(författare)
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Evidence that oestrogen receptor-alpha plays an important role in the regulation of glucose homeostasis in mice: insulin sensitivity in the liver
- 2006
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 49:3, s. 588-597
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: We used oestrogen receptor-alpha (ER alpha) knockout (ERKO) and receptor-beta (ER beta) knockout (BERKO) mice to investigate the mechanism(s) behind the effects of oestrogens on glucose homeostasis. Methods: Endogenous glucose production (EGP) was measured in ERKO mice using a euglycaemic-hyperinsulinaemic clamp. Insulin secretion was determined from isolated islets. In isolated muscles, glucose uptake was assayed by using radiolabelled isotopes. Genome-wide expression profiles were analysed by high-density oligonucleotide microarray assay, and the expression of the genes encoding steroyl-CoA desaturase and the Leptin receptor (Scd1 and Lepr, respectively) was confirmed by RT-PCR. Results: ERKO mice had higher fasting blood glucose, plasma insulin levels and IGT. The plasma leptin level was increased, while the adiponectin concentration was decreased in ERKO mice. Levels of both glucose- and arginine-induced insulin secretion from isolated islets were similar in ERKO and wild-type mice. The euglycaemic-hyperinsulinaemic clamp revealed that suppression of EGP by increased insulin levels was blunted in ERKO mice, which suggests a pronounced hepatic insulin resistance. Microarray analysis revealed that in ERKO mice, the genes involved in hepatic lipid biosynthesis were upregulated, while genes involved in lipid transport were downregulated. Notably, hepatic Lepr expression was decreased in ERKO mice. In vitro studies showed a modest decrease in insulin-mediated glucose uptake in soleus and extensor digitorum longus (EDL) muscles of ERKO mice. BERKO mice demonstrated normal glucose tolerance and insulin release. Conclusions/interpretation: We conclude that oestrogens, acting via ER alpha, regulate glucose homeostasis mainly by modulating hepatic insulin sensitivity, which can be due to the upregulation of lipogenic genes via the suppression of Lepr expression.
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| 8. |
- Fossati, L., et al.
(författare)
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Chemical evolution of A- and B-type stars in open clusters : observed abundances vs. diffusion models
- 2008
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Ingår i: Contributions of the Astronomical Observatory Skalnaté Pleso. - 1335-1842. ; 38:2, s. 123-128
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Tidskriftsartikel (refereegranskat)abstract
- We have decided to address the problem of how abundances and peculiarities change during main sequence evolution. We have setup a program to measure the atmospheric abundance patterns from tens of A-type star members of clusters of different ages, and compare the results with theory predictions. In this paper we present the overall project and we focus on the results obtained for a sample of Am stars of the Praesepe cluster (log t = 8.85 +/- 0.15; Gonzalez-Garcia et al., 2006). We have obtained spectra for eight Am stars, two normal A-type stars and one blue straggler, that are probable members of the Praesepe cluster. For all of these stars we have determined fundamental parameters and photospheric abundances for a large number of chemical elements. For seven stars we also obtained spectra in circular polarisation and applied the LSD technique to measure the mean longitudinal magnetic field. We have found good agreement between abundance predictions of diffusion models and measured abundances, except for Na and S. Li appears to be overabundant in three stars of our sample. No magnetic field was detected in any of the analysed stars.
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| 9. |
- Fossati, L., et al.
(författare)
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Late stages of the evolution of A-type stars on the main sequence : Comparison between observed chemical abundances and diffusion models for 8 Am stars of the Praesepe cluster
- 2007
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 476:2, s. 911-925
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We aim to provide observational constraints on diffusion models that predict peculiar chemical abundances in the atmospheres of Am stars. We also intend to check if chemical peculiarities and slow rotation can be explained by the presence of a weak magnetic field. Methods. We have obtained high resolution, high signal-to-noise ratio spectra of eight previously-classified Am stars, two normal A-type stars and one Blue Straggler, considered to be members of the Praesepe cluster. For all of these stars we have determined fundamental parameters and photospheric abundances for a large number of chemical elements, with a higher precision than was ever obtained before for this cluster. For seven of these stars we also obtained spectra in circular polarization and applied the LSD technique to constrain the longitudinal magnetic field. Results. No magnetic field was detected in any of the analysed stars. HD 73666, a Blue Straggler previously considered as an Ap (Si) star, turns out to have the abundances of a normal A-type star. Am classification is not confirmed for HD 72942. For HD 73709 we have also calculated synthetic Aa photometry that is in good agreement with the observations. There is a generally good agreement between abundance predictions of diffusion models and values that we have obtained for the remaining Am stars. However, the observed Na and S abundances deviate from the predictions by 0.6 dex and ≥0.25 dex respectively. Li appears to be overabundant in three stars of our sample.
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