159 research outputs found

    Theoretical developments on Quartic Gauge Boson Couplings at LEP

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    The search for quartic anomalous gauge couplings (QAGC) at LEP requires appropriate predictions for the radiative processes e+ e- \to \nu\bar\nu \gamma\gamma, e+ e- \to q\bar{q}\gamma\gamma and e+ e- \to 4 fermions+\gamma. The current knowledge on dimension-six operators giving rise to QAGC is briefly reviewed, together with their implementation in event generators. The accuracy of calculations based on real approximations (used up to now for the LEP experimental analysis) is examined by comparing them with the available exact matrix element calculations.Comment: LaTeX, JHEP style, 5 pag. Talk presented at EPS HEP2001, Budapest, Hungary, 12 - 18 July, 200

    Radiative four-fermion processes at LEP2

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    The production of four fermions plus a visible photon in electron-positron collisions is analyzed, with particular emphasis on the LEP2 energy range. The study is based on the calculation of exact matrix elements, including the effect of fermion masses. In the light of the present measurements performed at LEP, triple and quartic anomalous gauge couplings are taken into account. Due to the presence of a visible photon in the final state, particular attention is paid to the treatment of higher-order QED corrections. Explicit results for integrated cross sections and differential distributions are shown and commented. The features of the Monte Carlo program WRAP, used to perform the calculation and available for experimental analysis, are described.Comment: LaTeX, 14 pages, 6 tables, 13 figures. Numerical results added, version to appear in Eur. Phys. J.

    Quartic anomalous couplings at LEP

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    The search for quartic anomalous gauge couplings at LEP requires appropriate predictions for the radiative processes e+ e- \to \nu\bar\nu \gamma\gamma, e+ e- \to q\bar{q}\gamma\gamma and e+ e- \to 4 fermions+\gamma. Matrix elements are exactly computed at the tree level, and the effects of anomalous couplings and initial-state radiation are included. Comparisons with results and approximations existing in the literature are shown and commented. Improved versions of the event generators NUNUGPV and WRAP are made available for experimental analysis.Comment: LaTeX, 12 pages, 5 figures. Minor changes, version to appear in Phys. Lett.

    Adaptation of silage maize varieties under extreme northern growing condions in Finland

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    Trials with maize varieties from various places in the world were started in 1975. In preliminary trials in 1975, 280 varieties were tested. Between 19 and 23 varieties were selected for ordinary variety tests in 1976—78 at the University farm in Siuntio. Weather conditions, particularly average daily temperatures in 1975 were better than the long term averages, and in 1976—78 far below the average growing conditions. Dry matter yields of the seven harvested silage varieties in 1975 varied between 5.8 and 11.5 tons/ha. In 1976—78 the variation in DM yields was 3.8—8.0 tons/ha among 19—23 varieties. In 1975, 44 varieties out of 280 produced mature seed. Only one variety matured in 1978, but none in 1976—77. The developmental stage of silage maize is primarily determined by ear percentage and secondarily by DM %. In 1975 the average ear % of seven varieties was 49.1 %, in 1978 18.1 % and in 1976—77 only 4.0—5.7 % in DM. As a result of the variety tests promising varieties from Yugoslavia, France and Germany could be found. It can be concluded from the long term temperature data that with very early hybrid varieties a mature grain yield can be harvested twice in ten years. Good quality silage material can be harvested six times in ten years and a satisfactory crop can be obtained eight times in then years. The limiting factor for the growth and development of maize in Finland is the low average temperature of the growing season. Important but less significant is the length of the vegetative period, which is determined by the first killing frost in the fall. The temperature deficit is particularly critical at the beginning of the growing season

    Management techniques of maize crop in the marginal growing area in Finland

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    Silage maize management studies were carried out in 1976—78 on the University farm in Siuntio in southern Finland. Seeding time trials in 1976—77 consisted of three different types of varieties seeded at four different times between May 11 and June 8. In 1978 three seeding dates were tested in relation to the seeding depth of the maize. Population density studies were carried out in 1976—77. As a result of the management studies it can be concluded that the weather conditions were so unfavorable that true differences could not be found because even the best alternative in the management technique did not give a satisfactory agronomic result. Seeding dates from May 15 to May 25 can be recommended. Relatively heavy frosts in early June (—4°C to—6° C) will hurt stands but they do not kill the plant. The advance earned with early planting is thus not totally lost through the frosts Seeding depths of 5 to 7 cm are recommended. Population densities more than 10 plants/m2 are not necessary for the maximum yield. In average or better than average growing conditions the planting densities of 6 to 8 plants/m2 could yield a more mature forage crop

    Four-Fermion Production in Electron-Positron Collisions

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    This report summarises the results of the four-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the calculation of four-fermion processes in electron-positron collisions at LEP-2 centre-of-mass energies are presented, concentrating on predictions for four main reactions: W-pair production, visible photons in four-fermion events, single-W production and Z-pair production. Based on a comparison of results derived within different approaches, theoretical uncertainties on these predictions are established.Comment: 150 pages, 73 figures, 45 table

    Identification of a common risk haplotype for canine idiopathic epilepsy in the ADAM23 gene

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    Background: Idiopathic epilepsy is a common neurological disease in human and domestic dogs but relatively few risk genes have been identified to date. The seizure characteristics, including focal and generalised seizures, are similar between the two species, with gene discovery facilitated by the reduced genetic heterogeneity of purebred dogs. We have recently identified a risk locus for idiopathic epilepsy in the Belgian Shepherd breed on a 4.4 megabase region on CFA37. Results: We have expanded a previous study replicating the association with a combined analysis of 157 cases and 179 controls in three additional breeds: Schipperke, Finnish Spitz and Beagle (p(c) = 2.9e-07, p(GWAS) = 1.74E-02). A targeted resequencing of the 4.4 megabase region in twelve Belgian Shepherd cases and twelve controls with opposite haplotypes identified 37 case-specific variants within the ADAM23 gene. Twenty-seven variants were validated in 285 cases and 355 controls from four breeds, resulting in a strong replication of the ADAM23 locus (p(raw) = 2.76e-15) and the identification of a common 28 kb-risk haplotype in all four breeds. Risk haplotype was present in frequencies of 0.49-0.7 in the breeds, suggesting that ADAM23 is a low penetrance risk gene for canine epilepsy. Conclusions: These results implicate ADAM23 in common canine idiopathic epilepsy, although the causative variant remains yet to be identified. ADAM23 plays a role in synaptic transmission and interacts with known epilepsy genes, LGI1 and LGI2, and should be considered as a candidate gene for human epilepsies.Peer reviewe

    Exercise training with dietary counselling increases mitochondrial chaperone expression in middle-aged subjects with impaired glucose tolerance

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    <p>Abstract</p> <p>Background</p> <p>Insulin resistance and diabetes are associated with increased oxidative stress and impairment of cellular defence systems. Our purpose was to investigate the interaction between glucose metabolism, antioxidative capacity and heat shock protein (HSP) defence in different skeletal muscle phenotypes among middle-aged obese subjects during a long-term exercise and dietary intervention. As a sub-study of the Finnish Diabetes Prevention Study (DPS), 22 persons with impaired glucose tolerance (IGT) taking part in the intervention volunteered to give samples from the <it>vastus lateralis </it>muscle. Subjects were divided into two sub-groups (IGTslow and IGTfast) on the basis of their baseline myosin heavy chain profile. Glucose metabolism, oxidative stress and HSP expressions were measured before and after the 2-year intervention.</p> <p>Results</p> <p>Exercise training, combined with dietary counselling, increased the expression of mitochondrial chaperones HSP60 and glucose-regulated protein 75 (GRP75) in the <it>vastus lateralis </it>muscle in the IGTslow group and that of HSP60 in the IGTfast group. In cytoplasmic chaperones HSP72 or HSP90 no changes took place. In the IGTslow group, a significant positive correlation between the increased muscle content of HSP60 and the oxygen radical absorbing capacity values and, in the IGTfast group, between the improved VO<sub>2max </sub>value and the increased protein expression of GRP75 were found. Serum uric acid concentrations decreased in both sub-groups and serum protein carbonyl concentrations decreased in the IGTfast group.</p> <p>Conclusion</p> <p>The 2-year intervention up-regulated mitochondrial HSP expressions in middle-aged subjects with impaired glucose tolerance. These improvements, however, were not correlated directly with enhanced glucose tolerance.</p
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