| 1. |
- Abreu, P., et al.
(author)
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Search for sleptons in e+e- collisions at √s = 183 to 189 GeV
- 2001
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 29-42
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Journal article (peer-reviewed)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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| 2. |
- Abreu, P., et al.
(author)
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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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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 13:4, s. 573-589
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Journal article (peer-reviewed)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.
(author)
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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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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 15-28
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Journal article (peer-reviewed)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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| 4. |
- Petridou, E, et al.
(author)
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Endogenous risk factors for childhood leukemia in relation to the IGF system (Greece)
- 2000
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In: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 11:8, s. 765-771
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Journal article (peer-reviewed)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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| 5. |
- Petridou, E, et al.
(author)
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Insulin-like growth factor binding protein-3 predicts survival from acute childhood leukemia
- 2001
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In: Oncology. - : S. Karger AG. - 0030-2414 .- 1423-0232. ; 60:3, s. 252-257
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Journal article (peer-reviewed)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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| 6. |
- Skalkidou, A, et al.
(author)
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Birth size and neonatal levels of major components of the IGF system : implications for later risk of cancer.
- 2002
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In: Journal of Pediatric Endocrinology & Metabolism (JPEM). - 0334-018X .- 2191-0251. ; 15:9, s. 1479-86
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Journal article (peer-reviewed)abstract
- Pre- and perinatal conditions and processes may affect the risk for some forms of cancer in later life, while the insulin-like growth factor (IGF) system may play a role in both early somatic growth and later carcinogenesis. Birth weight and length, and the variation of major components of the IGF system immediately after birth, were analyzed in relation to selected physiological and pathological variables. The study comprised 331 healthy full-term newborns from whom blood samples were taken during routine phlebotomy no later than the fifth day of life. Measurements of IGF-I, IGF-II and IGF-binding protein-3 concentrations were performed. Birth length and weight were measured and information on socio-economic and medical variables was recorded. The concentrations of all three proteins were lower when blood bilirubin levels were high, possibly as a result of compromised liver function and/or as a component of an activated acute phase reaction. Birth weight was significantly higher by about 46 g among children whose IGF-I was higher by one SD, while the associations of birth weight and length with other components of the IGF system were in the predicted directions, albeit only in trend. We conclude that in early life, growth is related to the IGF system, mostly IGF-I. The latter is lower in children with jaundice, possibly because of hepatic dysfunction and/or as part of an acute phase reaction. We speculate that elevations of IGF-I in early life might explain the increased risk of cancer in individuals born with a higher birth weight.
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| 7. |
- Skalkidou, A, et al.
(author)
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Growth velocity during the first postnatal week of life is linked to a spurt of IGF-I effect.
- 2003
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In: Paediatric and Perinatal Epidemiology. - 0269-5022 .- 1365-3016. ; 17:3, s. 281-6
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Journal article (peer-reviewed)abstract
- There is adequate evidence that growth during the perinatal period is linked to the risk of several adult onset diseases, and recent findings indicate that the insulin-like growth factor (IGF) system is involved in prenatal growth, as reflected in birthweight. However, whether major components of the IGF system are involved in the immediate post-natal growth has not been studied. Maternal questionnaires were completed, and laboratory measurements of several variables, including IGF-I, IGF-II and IGF-binding protein-3 (IGFBP-3), were made for a total of 331 apparently healthy full-term newborns, from whom routine blood samples were taken during the first 5 days of their life. Birthweight and weight at the time of bleeding were among the recorded variables, and the difference divided by the age in days of the newborn was considered as reflecting immediate postnatal growth velocity. Immediate postnatal growth velocity was strongly positively associated with IGF-I. The squared adjusted correlation coefficient was 0.29 when IGF-I was incorporated in the model predicting postnatal growth velocity but was only 0.08 when IGF-I was excluded. In contrast, IGF-II and IGFBP-3 had no effect on postnatal growth velocity. It thus appears that IGF-I underlies growth during the immediate postnatal period. To the extent that perinatal growth may affect adult onset diseases, the findings of this study suggest that the action of IGF-I during the immediate postnatal period may represent a process of major importance.
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| 8. |
- Petridou, Eleni, et al.
(author)
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A role of sunshine in the triggering of suicide.
- 2002
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In: Epidemiology. - 1044-3983 .- 1531-5487. ; 13:1, s. 106-9
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Journal article (peer-reviewed)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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| 9. |
- Petridou, E, et al.
(author)
-
Are there common triggers of preterm deliveries?
- 2001
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In: British Journal of Obstetrics and Gynecology. - 1470-0328 .- 1471-0528. ; 108:6, s. 598-604
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To assess the effect(s) of transient events which are perceived as stressful on the inseption of preterm delivery.DESIGN: A case-control study, with immature infants as cases and borderline term babies as controls.SETTING: A teaching maternity hospital in Athens.POPULATION: All infants born at less than 37 weeks of gestation, during a twelve-month period.METHODS: Information was collected about maternal socio-demographic and lifestyle characteristics, clinical variables and stressful events occurring within two weeks prior to delivery.MAIN OUTCOME MEASURES: Factors affecting the risk of preterm delivery.RESULTS: Extreme prematurity (<33 weeks) is more common among younger (<25 years of age) and older (>29 years of age) women and is positively associated with parity, body mass index and smoking, whereas it is inversely associated with educational level, regular physical exercise and serious nausea/vomiting. After controlling for these factors, however, only coitus during the last weeks of pregnancy had a significant triggering effect on prematurity (P = 0.004, odds ratio 3.21, 95% CI 1.45 to 7.09 for very immature babies, and P = 0.04, OR = 2.20, 95% CI 1.03 to 4.70 for immature babies). On the contrary, several events perceived as stressful, such as illness of relatives or friends, husband's departure, loss of employment, were unrelated to the onset of premature labour.CONCLUSIONS: Coitus during the last few weeks of pregnancy appears to increase the risk of preterm delivery, while a possible detrimental effect of physical exertion seems more limited. Stressful events should not receive undue attention as possible causes of preterm delivery.
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| 10. |
- Petridou, E, et al.
(author)
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Evidence on the infectious etiology of childhood leukemia : the role of low herd immunity (Greece)
- 2001
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In: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 12:7, s. 645-652
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Journal article (peer-reviewed)abstract
- OBJECTIVE:Acute lymphoblastic leukemia (ALL) among children may be a rare outcome of a delayed non-specific infection in situations of overall low herd immunity. We evaluated the hypothesis as to whether newly diagnosed ALL cases, compared to their controls, are characterized by lower herd immunity, as reflected in a more seronegative spectrum to several agents, with the exception of a strongly positive response to a single infectious agent, assumed to trigger ALL.METHODS:The study included 94 incident cases of ALL, from all pediatric hematology-oncology units of Greece, and 94, matched for age and gender, controls hospitalized with minor non-infectious conditions. The past exposure to common infections was assessed using 10 serological markers.RESULTS:There was little evidence for an association of ALL with the serology of any of the studied infectious agents among the very young children. In contrast, among children aged 5 years or older, leukemia was inversely associated with seropositivity to Epstein-Barr virus, human herpes virus-6, Mycoplasma pneumoniae and parvovirus B19.CONCLUSIONS:Among children aged 5 years or older the risk of leukemia may be higher when the low herd immunity for several agents is challenged by late infection from an agent that, as a rule, would attack children at a younger age.
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| 11. |
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