| 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. |
- Abbondanno, U, et al.
(författare)
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The data acquisition system of the neutron time-of-flight facility n_TOF at CERN
- 2005
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 538:1-3, s. 692-702
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Tidskriftsartikel (refereegranskat)abstract
- The n_TOF facility at CERN has been designed for the measurement of neutron capture, fission and (n, xn) cross-sections with high accuracy. This requires a flexible and-due to the high instantaneous neutron flux-almost dead time free data acquisition system. A scalable and versatile data solution has been designed based on 8-bit flash-ADCs with sampling rates up to 2 GHz and 8 Mbyte memory buffer. The software is written in C and C++ and is running on PCs equipped with RedHat Linux.
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| 3. |
- Güsten, R., et al.
(författare)
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APEX - The Atacama Pathfinder Experiment
- 2006
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6267 I
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Konferensbidrag (refereegranskat)abstract
- APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the world's outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of 17-18 μm makes APEX suitable for observations up to 200 μm, through all atmospheric submm windows accessible from the ground.
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| 4. |
- Andersson, M., et al.
(författare)
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Using optical tweezers for measuring the interaction forces between human bone cells and implant surfaces: System design and force calibration
- 2007
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Ingår i: Rev Sci Instrum. - : AIP Publishing. ; 78:7
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Tidskriftsartikel (refereegranskat)abstract
- Optical tweezers were used to study the interaction and attachment of human bone cells to various types of medical implant materials. Ideally, the implant should facilitate cell attachment and promote migration of the progenitor cells in order to decrease the healing time. It is therefore of interest, in a controlled manner, to be able to monitor the cell adhesion process. Results from such studies would help foresee the clinical outcome of integrating medical implants. The interactions between two primary cell culture models, human gingival fibroblasts and bone forming human osteoblast cells, and three different implant materials, glass, titanium, and hydroxyapatite, were studied. A novel type of optical tweezers, which has a newly designed quadrant detector and a powerful 3 W laser was constructed and force calibrated using two different methods: one method in which the stiffness of the optical trap was obtained by monitoring the phase lag between the trap and the moved object when imposing a forced oscillation on the trapped object and another method in which the maximum trapping force was derived from the critical velocity at which the object escapes the trap. Polystyrene beads as well as cells were utilized for the calibrations. This is the first time that cells have been used directly for these types of force calibrations and, hence, direct measurements of forces exerted on cells can be performed, thus avoiding the difficulties often encountered when translating the results obtained from cell measurements to the calibrations obtained with reference materials. This more straightforward approach represents an advantage in comparison to established methods.
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| 5. |
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| 6. |
- Rvachev, MM, et al.
(författare)
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Quasielastic He-3(e,e(')p)H-2 reaction at Q(2)=1.5 GeV2 for recoil momenta up to 1 GeV/c
- 2005
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Ingår i: Physical Review Letters. - 1079-7114. ; 94:19
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the quasielastic He-3(e,e(')p)H-2 reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The He-3(e,e(')p)H-2 cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern He-3 wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models.
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| 7. |
- van Kuilenburg, André B P, et al.
(författare)
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Clinical, biochemical and genetic findings in two siblings with a dihydropyrimidinase deficiency
- 2007
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Ingår i: Molecular Genetics and Metabolism. - : Elsevier BV. - 1096-7192 .- 1096-7206. ; 91:2, s. 157-164
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Tidskriftsartikel (refereegranskat)abstract
- Dihydropyrimidinase (DHP) is the second enzyme of the pyrimidine degradation pathway and it catalyses the ring opening of 5,6-dihydrouracil and 5,6-dihydrothymine to N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid, respectively. To date, only nine individuals have been reported suffering from a complete DHP deficiency. We report two siblings presenting with strongly elevated levels of 5,6-dihydrouracil and 5,6-dihydrothymine in plasma, cerebrospinal fluid and urine. One of the siblings had a severe delay in speech development and white matter abnormalities, whereas the other one was free of symptoms. Analysis of the DHP gene (DPYS) showed that both patients were compound heterozygous for the missense mutation 1078T>C (W360R) in exon 6 and a novel missense mutation 1235G>T (R412M) in exon 7. Heterologous expression of the mutant enzymes in Escherichia coli showed that both missense mutations resulted in a mutant DHP enzyme without residual activity. Analysis of the crystal structure of eukaryotic DHP from the yeast Saccharomyces kluyveri and the slime mold Dictyostelium discoideum suggests that the W360R and R412M mutations lead to structural instability of the enzyme which could potentially impair the assembly of the tetramer.
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| 8. |
- van Kuilenburg, A B P, et al.
(författare)
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Identification of two novel mutations C79X and R235Q in the dihydropyrimidine dehydrogenase gene in a patient presenting with hematuria
- 2008
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Ingår i: Nucleosides, Nucleotides & Nucleic Acids. - : Informa UK Limited. - 1525-7770 .- 1532-2335. ; 27:6-7, s. 809-815
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Tidskriftsartikel (refereegranskat)abstract
- A patient with hematuria was shown to have thymine-uraciluria. The dihydropyrimidine dehydrogenase (DPD) activity in peripheral blood mononuclear cells was 0.16 nmol/mg/h; controls: 9.9 +/- 2.8 nmol/mg/h. Analysis of DPYD showed that the patient was compound heterozygous for the novel mutations 237C > A (C79X) in exon 4 and 704G > A (R235Q) in exon 7. The nonsense mutation (C79X) leads to premature termination of translation and thus to a non-functional protein. Analysis of the crystal structure of pig DPD suggested that the R235Q mutation might interfere with the binding of FAD and the electron flow between the NADPH and the pyrimidine substrate site of DPD.
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| 9. |
- Accordini, S, et al.
(författare)
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The socio-economic burden of asthma is substantial in Europe
- 2008
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : Wiley. - 0105-4538 .- 1398-9995. ; 63:1, s. 116-124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Few data are available on the asthma burden in the general population. We evaluated the level and the factors associated with the asthma burden in Europe. METHODS: In 1999-2002, 1152 adult asthmatics were identified in the European Community Respiratory Health Survey (ECRHS)-II and the socio-economic burden (reduced activity days and hospital services utilization in the past 12 months) was assessed. RESULTS: The asthmatics with a light burden (only a few reduced activity days) were 13.2% (95% CI: 11.4-15.3%), whereas those with a heavy burden (many reduced activity days and/or hospital services utilization) were 14.0% (95% CI: 12.1-16.1%). The burden was strongly associated with disease severity and a lower quality of life. Obese asthmatics had a significantly increased risk of a light [relative risk ratio (RRR) = 2.17; 95% CI: 1.18-4.00] or a heavy burden (RRR = 2.77; 95% CI: 1.52-5.05) compared with normal/underweight subjects. The asthmatics with frequent respiratory symptoms showed a threefold (RRR = 2.74; 95% CI: 1.63-4.61) and sixfold (RRR = 5.76; 95% CI: 3.25-10.20) increased risk of a light or a heavy burden compared with asymptomatic asthmatics, respectively. Moreover, the lower the forced expiratory volume in 1 s % predicted, the higher the risk of a heavy burden. The coexistence with chronic cough/phlegm only increased the risk of a heavy burden (RRR = 1.88; 95% CI: 1.16-3.06). An interaction was found between gender and IgE sensitization, with nonatopic asthmatic females showing the highest risk of a heavy burden (21.6%; 95% CI: 16.9-27.1%). CONCLUSIONS: The asthma burden is substantial in Europe. A heavy burden is more common in asthmatics with obesity, frequent respiratory symptoms, low lung function, chronic cough/phlegm and in nonatopic females.
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| 10. |
- Andersson, Martin, 1974, et al.
(författare)
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Detection of single ion channel activity on a chip using tethered bilayer membranes
- 2007
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 23:6, s. 2924-2927
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Tidskriftsartikel (refereegranskat)abstract
- Membrane-bound ion channels are promising biological receptors since they allow for the stochastic detection of analytes at high sensitivity. For stochastic sensing, it is necessary to measure the ion currents associated with single ion channel opening and closing events. However, this calls for stability, high reproducibility, and long lifetimes. A critical issue to overcome is the low stability of the ion channel environment, that is, the bilayer membrane. A promising technique to surmount this is to connect the lower part of the membrane to a surface forming a tethered bilayer membrane. By reconstituting the synthetic ion channel, gramicidin A, into a tethered bilayer as part of a microchip design, we have been able to record the activity of single ion channels. The observed activity was compared with that obtained by a conventional electrophysiology method, tip dipping, to confirm its authenticity. These findings allow for the construction of stable biosensors based on ion channels and provide a novel technique for the characterization of ion channel activity.
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