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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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| 2. |
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| 3. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
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Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
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Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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| 4. |
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| 5. |
- Peacock, Christopher S, et al.
(författare)
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Comparative genomic analysis of three Leishmania species that cause diverse human disease.
- 2007
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 39:7, s. 839-847
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Tidskriftsartikel (refereegranskat)abstract
- Leishmania parasites cause a broad spectrum of clinical disease. Here we report the sequencing of the genomes of two species of Leishmania: Leishmania infantum and Leishmania braziliensis. The comparison of these sequences with the published genome of Leishmania major reveals marked conservation of synteny and identifies only 200 genes with a differential distribution between the three species. L. braziliensis, contrary to Leishmania species examined so far, possesses components of a putative RNA-mediated interference pathway, telomere-associated transposable elements and spliced leader–associated SLACS retrotransposons. We show that pseudogene formation and gene loss are the principal forces shaping the different genomes. Genes that are differentially distributed between the species encode proteins implicated in host-pathogen interactions and parasite survival in the macrophage.
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| 8. |
- Henkel, C., et al.
(författare)
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The density, the cosmic microwave background, and the proton-to-electron mass ratio in a cloud at redshift 0.9
- 2009
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 500:2, s. 725-734
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Tidskriftsartikel (refereegranskat)abstract
- Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the gravitational lens system PKS 1830-211, which is by far the best known target to study dense cool gas in absorption at intermediate redshift. Determining average radial velocities and performing Large Velocity Gradient radiative transfer calculations, the aims of this study are (1) to determine the density of the gas, (2) to constrain the temperature of the cosmic microwave background (CMB), and (3) to evaluate the proton-to-electron mass ratio at redshift z ˜ 0.89. Analyzing data from six rotational HC3N transitions (this includes the J=7≤ftarrow6 line, which is likely detected for the first time in the interstellar medium) we obtain n(H2) ~ 2600 cm-3 for the gas density of the south-western absorption component, assuming a background source covering factor, which is independent of frequency. With a possibly more realistic frequency dependence proportional to ν0.5 (the maximal exponent permitted by observational boundary conditions), n(H2) ~ 1700 cm-3. Again toward the south-western source, excitation temperatures of molecular species with optically thin lines and higher rotational constants are, on average, consistent with the expected temperature of the cosmic microwave background, T_CMB = 5.14 K. However, individually, there is a surprisingly large scatter which far surpasses expected uncertainties. A comparison of CS J =1 ≤ftarrow0 and 4≤ftarrow3 optical depths toward the weaker north-western absorption component results in T_ex = 11 K and a 1-σ error of 3 K. For the main component, a comparison of velocities determined from ten optically thin NH3 inversion lines with those from five optically thin rotational transitions of HC3N, observed at similar frequencies, constrains potential variations of the proton-to-electron mass ratio μ to Δμ / μ
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| 9. |
- Mangles, SPD, et al.
(författare)
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Effect of contrast ratio on electron beam stability in laser wakefield acceleration experiments
- 2006
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335. ; 48:12B, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- Laser wakefield accelerators offer the possibility of compact electron acceleration. However one of the key outstanding issues with the results reported to date is the electron beam stability. Experiments on two laser systems reveal that the contrast ratio between the ASE pedestal and main pulse is an important factor in determining the quality of the electron beam. With a high contrast ratio (10^8) the electron beam profile is a well collimated single beam having a low pointing instability (<10 mrad rms). With a lower contrast (10^6) the beam profile contains multiple beamlets which exhibit a large pointing instability (~50 mrad rms). Ahigh contrast ratio not only improves the beam pointing stability (~6 mrad) but also stabilizes the electron beam energy reproducibility (5%).
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| 10. |
- Trines, R. M. G. M., et al.
(författare)
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Applications of the wave kinetic approach : from laser wakefields to drift wave turbulence
- 2009
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 16:5, s. 055904-
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear wave-driven processes in plasmas are normally described by either a monochromatic pump wave that couples to other monochromatic waves or as a random phase wave coupling to other random phase waves. An alternative approach involves a random or broadband pump coupling to monochromatic and/or coherent structures in the plasma. This approach can be implemented through the wave kinetic model. In this model, the incoming pump wave is described by either a bunch (for coherent waves) or a sea (for random phase waves) of quasiparticles. This approach has been applied to both photon acceleration in laser wakefields and drift wave turbulence in magnetized plasma edge configurations. Numerical simulations have been compared to experiments, varying from photon acceleration to drift mode-zonal flow turbulence, and good qualitative correspondences have been found in all cases.
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