| 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. |
- Ashley, S. F., et al.
(författare)
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Lifetime determination of excited states in Cd-106
- 2007
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 38:4, s. 1385-1388
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Tidskriftsartikel (refereegranskat)abstract
- Two separate experiments using the Differential Decay Curve Method have been performed to extract mean lifetimes of excited states in 106 Cd. The inedium-spin states of interest were populated by the Mo-98(C-12, 4n) Cd-106 reaction performed at the Wright Nuclear Structure Lab., Yale University. From this experiment, two isomeric state mean lifetimes have been deduced. The low-lying states were populated by the Mo-96(C-13, 3n)Cd-106 reaction performed at the Institut fur Kernphysik, Universitat zu Koln. The mean lifetime of the I-pi = 2(1)(+) state was deduced, tentatively, as 16.4(9) ps. This value differs from the previously accepted literature value from Coulomb excitation of 10.43(9) ps.
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| 3. |
- Johnston, M. O., et al.
(författare)
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Correlations among fertility components can maintain mixed mating in plants
- 2009
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Ingår i: American Naturalist. - 0003-0147 .- 1537-5323. ; 173:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Classical models studying the evolution of self-fertilization in plants conclude that only complete selfing and complete outcrossing are evolutionarily stable. In contrast with this prediction, 42% of seed-plant species are reported to have rates of self-fertilization between 0.2 and 0.8. We propose that many previous models fail to predict intermediate selfing rates because they do not allow for functional relationships among three components of reproductive fitness: self-fertilized ovules, outcrossed ovules, and ovules sired by successful pollen export. Because the optimal design for fertility components may differ, conflicts among the alternative pathways to fitness are possible, and the greatest fertility may be achieved with some self-fertilization. Here we develop and analyze a model to predict optimal selfing rates that includes a range of possible relationships among the three components of reproductive fitness, as well as the effects of evolving inbreeding depression caused by deleterious mutations and of selection on total seed number. We demonstrate that intermediate selfing is optimal for a wide variety of relationships among fitness components and that inbreeding depression is not a good predictor of selfing-rate evolution. Functional relationships subsume the myriad effects of individual plant traits and thus offer a more general and simpler perspective on mating system evolution.
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| 4. |
- Chapman, Henry N., et al.
(författare)
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Femtosecond diffractive imaging with a soft-X-ray free-electron laser
- 2006
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2473 .- 1745-2481. ; 2:12, s. 839-843
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Tidskriftsartikel (refereegranskat)abstract
- Theory predicts(1-4) that, with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft-X-ray free-electron laser. An intense 25 fs, 4 x 10(13) W cm(-2) pulse, containing 10(12) photons at 32 nm wavelength, produced a coherent diffraction pattern from a nanostructured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single-photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling(5-9), shows no measurable damage, and is reconstructed at the diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one(10).
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| 5. |
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| 6. |
- Blomqvist, M., et al.
(författare)
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Structural and tribological properties of cluster-assembled CNx films
- 2007
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 87:4, s. 767-772
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Tidskriftsartikel (refereegranskat)abstract
- We report the structural and tribological characterization of nanostructured CNx thin films produced by the deposition of a supersonic carbon cluster beam assisted by nitrogen ion bombardment. The influence of the deposition parameters on the chemical composition and structure of the films has been systematically studied by X-ray photoelectron spectroscopy, elastic recoil detection analysis, transmission electron microscopy and atomic force microscopy. Depending on the deposition parameters, the films show a structure ranging from amorphous to disordered graphitic with interlinked planes. Nitrogen content depends on the nitrogen ion kinetic energy. The films have a very low density with a high surface roughness. Friction measurements at the nanoscale show a correlation between nitrogen content and mechanical properties of the system.
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| 7. |
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| 8. |
- Fuchs, A., et al.
(författare)
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Nanowire fin field effect transistors via UV-based nanoimprint lithography
- 2006
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 24:6, s. 2964-2967
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Tidskriftsartikel (refereegranskat)abstract
- A triple step alignment process for UV nanoimprint lithography (UV-NIL) for the fabrication of nanoscale fin field effect transistors (FinFETs) is presented. An alignment accuracy is demonstrated between two functional layers of less than 20 nm (3 sigma). The electrical characterization of the FinFETs fabricated by a full NIL process demonstrates the potential of UV-NIL for future nanoelectronic devices.
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| 9. |
- Moeller, P., et al.
(författare)
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Axial and reflection asymmetry of the nuclear ground state
- 2008
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier BV. - 0092-640X. ; 94:5, s. 758-780
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Tidskriftsartikel (refereegranskat)abstract
- More than a decade ago we published a calculation of nuclear ground-state masses and deformations in Atomic Data and Nuclear Data Tables [P. Moller, J.R. Nix, W.D. Myers, W.J. Swiatecki, At. Data Nucl. Data Tables 59 (1995) 185]. In this study, triaxial nuclear shapes were not considered. We have now enhanced our model and studied the influence of triaxial shape degrees of freedom on the nuclear ground-state potential-energy (mass) and ground-state shape. It turns out that a few hundred nuclei are affected to a varying degree with the largest effect, about 0.7 MeV, occurring near Ru-108. We provide here a table of the calculated effects of triaxial shape degrees of freedom. Although axial-asymmetry effects were not considered in the 1995 mass calculation, it did study the effects of reflection-asymmetric shape degrees of freedom (epsilon(3)) on nuclear masses. However, the magnitude of the effect was not tabulated. Here, we provide such a table. In addition we calculate the effect in a much improved fashion: we search a four-dimensional deformation space (epsilon(2), epsilon(3), epsilon(4), and epsilon(6)). This is now possible because the computational resources available to us today are more than 100,000 times better than at the time we calculated the mass table published in 1995. (C) 2008 Elsevier Inc. All rights reserved.
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| 10. |
- Schumann, Stefan, et al.
(författare)
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Detection of partial endotracheal tube obstruction by forced pressure oscillations
- 2007
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 155:3, s. 227-233
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Tidskriftsartikel (refereegranskat)abstract
- Rapid airway occlusions during mechanical ventilation are followed immediately by high-frequency pressure oscillations. To answer the question if the frequency of forced pressure oscillations is an indicator for partial obstruction of the endotracheal tube (ETT) we performed mathematical simulations and studies in a ventilated physical lung model. Model-derived predictions were evaluated in seven healthy volunteers. Partial ETT obstruction was mimicked by decreasing the inner diameter (ID) of the ETT. In the physical model ETTs of different ID were used. In spontaneously breathing volunteers viscous fluid was applied into the ETT's lumen. According to the predictions derived from mathematical simulations, narrowing of the ETT's ID from 9.0 to 7.0 mm decreased the frequency of the pressure oscillations by 11% while changes of the respiratory system's compliance had no effect. In volunteers, a similar reduction (10.9%) was found when 5 ml fluid were applied. We conclude that analysis of pressure oscillations after flow interruption offers a tool for non-invasive detection of partial ETT obstruction.
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