| 1. |
- Schael, S, et al.
(författare)
-
Precision electroweak measurements on the Z resonance
- 2006
-
Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
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.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Buker, P, et al.
(författare)
-
Comparison of different stomatal conductance algorithms for ozone flux modelling
- 2005
-
Ingår i: UNECE – Workshop “Critical Levels of Ozone: Further applying and developing the flux-based concept”, Obergurgl, 15-19 November 2005.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two widely used algorithms for modelling stomatal conductance (gs) were compared in order to evaluate the approach leading to the most realistic predictions of stomatal fluxes to vegetated surfaces: a multiplicative algorithm initially developed by Jarvis (1976) and refined by Emberson et al. (2000) (DO3SE ) and a photosynthesis-based Ball&Berry-type algorithm developed by Nikolov et al. (1995) (LEAFC3). Both models were parameterised for several crop and tree species (wheat, grapevine, Scots pine, beech and birch) and have been applied to various datasets – with the main focus on wheat - representing different European regions (North, Central and South Europe). A sensitivity analysis has been carried out for both models to evaluate the dependence of gs on the meteorological parameters temperature, photosynthetic active radiation and vapour pressure deficit. Furthermore, in order to test whether a general species-specific parameterisation can account for differences in gs due to plants growing under different climatic conditions throughout Europe, the models have been re-parameterised for local meteorological conditions. A direct comparison of both models showed that the net photosynthetic-based model required more detailed meteorological (e.g. ambient CO2-concentration, dew-point temperature) and plant-physiological (e.g. Vcmax and Jmax) input parameters while not delivering a substantially higher R2 when comparing measured and modelled gs. The relative weakness of the multiplicative model lies in its dependence on the maximum stomatal conductance (gmax), whereas the photosynthesis-based model is not taking into account phenology-related changes in gs. Furthermore, the results show that an equally close relationship between gs and net photosynthetic rate throughout the entire growing season is questionable. We conclude that the multiplicative approach is favourable for calculating stomatal fluxes on a wider scale (e.g. within EMEP-deposition model), whereas the photosynthesis-based approach is a potential alternative for modelling fluxes on a local scale.
|
|
| 5. |
- Costa, Y, et al.
(författare)
-
Two novel proteins recruited by synaptonemal complex protein 1 (SYCP1) are at the centre of meiosis
- 2005
-
Ingår i: Journal of cell science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 118:12Pt 12, s. 2755-2762
-
Tidskriftsartikel (refereegranskat)abstract
- Completion of meiosis in mammals depends on the formation of the synaptonemal complex, a tripartite structure that physically links homologous chromosomes during prophase I. Several components of the synaptonemal complex are known, including constituents of the cohesin core, the axial/lateral element and the transverse filaments. No protein has previously been identified as an exclusive component of the central element. Mutations in some synaptonemal-complex proteins results in impaired meiosis. In humans, cases of male infertility have been associated with failure to build the synaptonemal complex. To search for new components of the meiotic machinery, we have used data from microarray expression profiling and found two proteins localising solely to the central element of the mammalian synaptonemal complex. These new proteins, SYCE1 and CESC1, interact with the transverse filament protein SYCP1, and their localisation to the central element appears to depend on recruitment by SYCP1. This suggests a role for SYCE1 and CESC1 in synaptonemal-complex assembly, and perhaps also stability and recombination.
|
|
| 6. |
|
|
| 7. |
- Hamer, G, et al.
(författare)
-
Characterization of a novel meiosis-specific protein within the central element of the synaptonemal complex
- 2006
-
Ingår i: Journal of cell science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 119:19Pt 19, s. 4025-4032
-
Tidskriftsartikel (refereegranskat)abstract
- During the first meiotic prophase, alignment and synapsis of the homologous chromosomes are mediated by the synaptonemal complex. Incorrect assembly of this complex results in cell death, impaired meiotic recombination and formation of aneuploid germ cells. We have identified a novel mouse meiosis-specific protein, TEX12, and shown it to be a component of the central element structure of the synaptonemal complex at synapsed homologous chromosomes. Only two other central element proteins, SYCE1 and SYCE2, have been identified to date and, using several mouse knockout models, we show that these proteins and TEX12 specifically depend on the synaptonemal transverse filament protein SYCP1 for localization to the meiotic chromosomes. Additionally, we show that TEX12 exactly co-localized with SYCE2, having the same, often punctate, localization pattern. SYCE1, on the other hand, co-localized with SYCP1 and these proteins displayed the same more continuous expression pattern. These co-localization studies were confirmed by co-immunoprecipitation experiments that showed that TEX12 specifically co-precipitated with SYCE2. Our results suggest a molecular network within the central elements, in which TEX12 and SYCE2 form a complex that interacts with SYCE1. SYCE1 interacts more directly with SYCP1 and could thus anchor the central element proteins to the transverse filaments.
|
|
| 8. |
- Karlsson, Per Erik, 1957, et al.
(författare)
-
Risk assessments for forest trees: The performance of the ozone flux versus the AOT concepts
- 2007
-
Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 146:3, s. 608-616
-
Tidskriftsartikel (refereegranskat)abstract
- Published ozone exposure-response relationships from experimental studies with young trees performed at different sites across Europe were re-analysed in order to test the performance of ozone exposure indices based on AOTX (Accumulated exposure Over a Threshold of X nmol mol(-1)) and AF(st)Y (Accumulated Stomatal Flux above a threshold of Y nmol m(-2) s(-1)). AF(st)1.6 was superior, as compared to AOT40, for explaining biomass reductions, when ozone sensitive species with differing leaf morphology were included in the analysis, while this was not the case for less sensitive species. A re-analysis of data with young black cherry trees, subject to different irrigation regimes, indicated that leaf visible injuries were more strongly related to the estimated stomatal ozone uptake, as compared to the ozone concentration in the air. Experimental data with different clones of silver birch indicated that leaf thickness was also an important factor influencing the development of ozone induced leaf visible injury. (c) 2006 Elsevier Ltd. All rights reserved.
|
|
| 9. |
|
|
| 10. |
- Novak, P., et al.
(författare)
-
Magnetism in the magnetoelectric hexaferrite system (Ba1-xSrx)(2)Zn2Fe12O22
- 2007
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 76:2, s. 024432-
-
Tidskriftsartikel (refereegranskat)abstract
- The hexaferrite system (Ba1-xSrx)(2)Zn2Fe12O22 possesses a rich magnetic phase diagram and for strontium content x=0.75 exhibits a magnetoelectricity, the existence of which is intimately connected to the noncollinear arrangement of the iron spins. The system comprises seven cation sublattices, two of which have tetrahedral coordination. The tetrahedral sublattices are partly occupied by Fe and partly by Zn. Using ab initio-calculated exchange interactions we show that the magnetism in the (Ba1-xSrx)(2)Zn2Fe12O22 system is sensitive to the Fe and Zn distributions. The region of existence of the noncollinear spin structure and hence of ferroelectricity is determined and found to be rather narrow. The critical temperature of magnetic ordering is calculated using molecular field and random phase approximations. The results are in good agreement with the experiment.
|
|
