| 1. |
- Abreu, P., et al.
(författare)
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Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP
- 2001
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 15-28
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Tidskriftsartikel (refereegranskat)abstract
- Muon pair production in the process e+e- → e+e- μ+μ- is studied using the data taken at LEP1 (√s ≃ mz) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb-1. The QED predictions have been tested over the whole Q2 range accessible at LEP1 (from several GeV2/c4 to several hundred GeV2/c4) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function Fγ 2. Azimuthal correlations are used to obtain information on additional structure functions, Fγ A and Fγ B, which originate from interference terms of the scattering amplitudes. The measured ratios Fγ A/Fγ 2 and FγB/Fγ 2 are significantly different from zero and consistent with QED predictions.
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| 2. |
- Abreu, P., et al.
(författare)
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Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets
- 2000
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 13:4, s. 573-589
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the DELPHI detector at the Z resonance between 1992 and 995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy e+e- annihilation experiments. For gluon jets it appears to be significantly stronger. The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio CA/CF is measured to be: CA/CF = 2.26 ± 0.09stat. ± 0.06sys. ± 0.12clus.,scale..
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| 3. |
- Abreu, P., et al.
(författare)
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Search for sleptons in e+e- collisions at √s = 183 to 189 GeV
- 2001
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 29-42
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Tidskriftsartikel (refereegranskat)abstract
- Data taken by the DELPHI experiment at centre-of-mass energies of 183 GeV and 189 GeV with a total integrated luminosity of 212 pb-1 have been used to search for the supersymmetric partners of the electrons, muons, and taus in the context of the Minimal Supersymmetric Standard Model (MSSM). The decay topologies searched for were the direct decay (ℓ̃ → ℓx̃), producing acoplanar lepton pairs plus missing energy, and the cascade decay (ℓ → ℓx̃0 2 → ℓγx̃0 1), producing acoplanar lepton and photon pairs plus missing energy. The observed number of events is in agreement with Standard Model predictions. The 95% CL excluded mass limits for selectrons, smuons and staus are mẽ ≤ 87 GeV/c2, mμ̃ ≤ 80 GeV/c2 and mτ̃ 75 GeV/c2, respectively, for values of μ=-200 GeV/c2 and tanβ=1.5.
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| 4. |
- Petridou, Eleni, et al.
(författare)
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A role of sunshine in the triggering of suicide.
- 2002
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Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 13:1, s. 106-9
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Tidskriftsartikel (refereegranskat)abstract
- Several reports indicate that suicide follows a seasonal pattern with a dominant peak during the month of maximum daylight. The purpose of this study was to evaluate the hypothesis that sunshine exposure may trigger suicidal behavior. We found a remarkably consistent pattern of seasonality with peak incidence around June in the northern hemisphere and December in the southern hemisphere. Moreover, there was a positive association between the seasonal amplitude of suicide (measured by relative risk) and total sunshine in the corresponding country. These findings indicate that sunshine may have a triggering effect on suicide, and suggests further research in the field of sunshine-regulated hormones, particularly melatonin.
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| 5. |
- Petridou, E, et al.
(författare)
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Endogenous risk factors for childhood leukemia in relation to the IGF system (Greece)
- 2000
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Ingår i: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 11:8, s. 765-771
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:Insulin-like growth factor-1 (IGF-1) and its principal binding protein-3 (IGFBP-3) are central in the mediation of the effect of growth hormone, and the IGF system has been reported to play a role in the pathogenesis of childhood leukemia.METHODS:To further evaluate the hypothesis connecting the IGF system to this disease, we have examined whether IGF-1 and IGFBP-3 are associated with the two main endogenous risk factors for childhood leukemia, namely gender and birth weight, since boys and heavier newborns are known to be at higher risk. IGF-1 and IGFBP-3 were measured under code in the serum of 118 apparently healthy children aged 0-14 years and the values of each of these components were regressed on age, gender and birth weight. Insulin-like growth factor-2 (IGF-2), as a dependent variable, and anemia during the corresponding pregnancy, as a predictor variable, were also evaluated for exploratory purposes.RESULTS:In the total data set, IGF-1 was positively associated with birth weight (p = 0.0001), whereas girls had higher levels of IGFBP-3 (p = 0.01).CONCLUSIONS:It appears that the associations of measured components of the IGF system with the examined risk factors for childhood leukemia are largely compatible with those that would have been expected, if this system played a role in the pathogenesis of childhood leukemia.
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| 6. |
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| 7. |
- Petridou, E, et al.
(författare)
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Insulin-like growth factor binding protein-3 predicts survival from acute childhood leukemia
- 2001
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Ingår i: Oncology. - : S. Karger AG. - 0030-2414 .- 1423-0232. ; 60:3, s. 252-257
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:To investigate whether the three principal components of the insulin-like growth factor (IGF) system, IGF-1, IGF-2 and IGF binding protein-3 (IGFBP-3), are associated with survival from childhood leukemia.PATIENTS AND METHODS:116 children, 0--14 years old, with newly diagnosed and bone-marrow-biopsy-confirmed acute childhood leukemia between 1993 and 1996 were followed up until death or March 31, 1998. IGF-1, IGF-2 and IGFBP-3 were measured at diagnosis and clinical data, including presence of hepatosplenomegaly and number of white blood cells, were available.RESULTS:After controlling for gender, age, indicators of clinical severity and the other measured components of the IGF system there was a statistically significant (p < 0.05) inverse association of IGFBP-3 with survival. An increment of one standard deviation in IGFBP-3 was associated with a 65% reduction of the death hazard among the children with leukemia. Neither IGF-1 nor IGF-2 was associated with survival in this data set.CONCLUSION:The presented empirical evidence in conjunction with the fact that IGFBP-3 modulates IGF-1 and IGF-2 bioavailability and is likely to have proapoptotic effects makes this compound a plausible independent predictor of survival from childhood leukemia.
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