Predictors of cardiac troponin release after a marathon

Objectives: Exercise leads to an increase in cardiac troponin I in healthy, asymptomatic athletes after a marathon. Previous studies revealed single factors to relate to post-race cardiac troponin I levels. Integrating these factors into our study, we aimed to identify independent predictors for the exercise-induced cardiac troponin I release. Design: Observational study. Methods: Ninety-two participants participated in a marathon at a self-selected speed. Demographic data, health status, physical activity levels and marathon experience were obtained. Before and immediately after the marathon fluid intake was recorded, body mass changes were measured to determine fluid balance and venous blood was drawn for analysis of high-sensitive cardiac troponin I. Exercise intensity was examined by recording heart rate. We included age, participation in previous marathons, exercise duration, exercise intensity and hydration status (relative weight change) in our model as potential determinants to predict post-exercise cardiac troponin I level. Results: Cardiac troponin I increased significantly from 14. ±. 12. ng/L at baseline to 94. ±. 102. ng/L post-race, with 69% of the participants demonstrating cardiac troponin I levels above the clinical cut-off value (40. ng/L) for an acute myocardial infarction. Linear backward regression analysis identified younger age (β=. -0.27) and longer exercise duration (β=. 0.23) as significant predictors of higher post-race cardiac troponin I levels (total r=. 0.31, p<. 0.05), but not participation in previous marathons, relative weight change and exercise intensity. Conclusions: We found that cardiac troponin I levels significantly increased in a large heterogeneous group of athletes after completing a marathon. The magnitude of this response could only be partially explained, with a lower age and longer exercise duration being related to higher post-race cardiac troponin I levels

Bose-Einstein Correlations of Neutral and Charged Pions in Hadronic Z Decays

Bose-Einstein correlations of both neutral and like-sign charged pion pairs are measured in a sample of 2 million hadronic Z decays collected with the L3 detector at LEP. The analysis is performed in the four-momentum difference range 300 MeV < Q < 2 GeV. The radius of the neutral pion source is found to be smaller than that of charged pions. This result is in qualitative agreement with the string fragmentation model

Measurement of the W+W-gamma Cross Section and Direct Limits on Anomalous Quartic Gauge Boson Couplings at LEP

The process e+e- -> W+W-gamma is analysed using the data collected with the L3 detector at LEP at a centre-of-mass energy of 188.6GeV, corresponding to an integrated luminosity of 176.8pb^-1. Based on a sample of 42 selected W+W- candidates containing an isolated hard photon, the W+W-gamma cross section, defined within phase-space cuts, is measured to be: sigma_WWgamma = 290 +/- 80 +/- 16 fb, consistent with the Standard Model expectation. Including the process e+e- -> nu nu gamma gamma, limits are derived on anomalous contributions to the Standard Model quartic vertices W+W- gamma gamma and W+W-Z gamma at 95% CL: -0.043 GeV^-2 < a_0/Lambda^2 < 0.043 GeV^-2 0.08 GeV^-2 < a_c/Lambda^2 < 0.13 GeV^-2 0.41 GeV^-2 < a_n/Lambda^2 < 0.37 GeV^-2

Production of Single W Bosons at \sqrt{s}=189 GeV and Measurement of WWgamma Gauge Couplings

Single W boson production in electron-positron collisions is studied with the L3 detector at LEP. The data sample collected at a centre-of-mass energy of \sqrt{s} = 188.7GeV corresponds to an integrated luminosity of 176.4pb^-1. Events with a single energetic lepton or two acoplanar hadronic jets are selected. Within phase-space cuts, the total cross-section is measured to be 0.53 +/- 0.12 +/- 0.03 pb, consistent with the Standard Model expectation. Including our single W boson results obtained at lower \sqrt{s}, the WWgamma gauge couplings kappa_gamma and lambda_gamma are determined to be kappa_gamma = 0.93 +/- 0.16 +/- 0.09 and lambda_gamma = -0.31 +0.68 -0.19 +/- 0.13

Search for an invisibly decaying Higgs boson in e^+e^- collisions at \sqrt{s} = 183 - 189 GeV

A search for a Higgs boson decaying into invisible particles is performed using the data collected at LEP by the L3 experiment at centre-of-mass energies of 183 GeV and 189 GeV. The integrated luminosities are respectively 55.3 pb^-1 and 176.4 pb^-1. The observed candidates are consistent with the expectations from Standard Model processes. In the hypothesis that the production cross section of this Higgs boson equals the Standard Model one and the branching ratio into invisible particles is 100%, a lower mass limit of 89.2 GeV is set at 95% confidence level

Search for Heavy Neutral and Charged Leptons in e+ e- Annihilation at LEP

A search for exotic unstable neutral and charged heavy leptons as well as for stable charged heavy leptons is performed with the L3 detector at LEP. Sequential, vector and mirror natures of heavy leptons are considered. No evidence for their existence is found and lower limits on their masses are set

Search for Neutral Higgs Bosons of the Minimal Supersymmetric Standard Model in e+e- Interactions at \sqrt{s} = 189 GeV

A search for the lightest neutral scalar and neutral pseudoscalar Higgs bosons in the Minimal Supersymmetric Standard Model is performed using 176.4 pb^-1 of integrated luminosity collected by L3 at a center-of-mass energy of 189 GeV. No signal is observed, and the data are consistent with the expected Standard Model background. Lower limits on the masses of the lightest neutral scalar and pseudoscalar Higgs bosons are given as a function of tan(beta). Lower mass limits for tan(beta)>1 are set at the 95% confidence level to be m_h > 77.1 GeV and m_A > 77.1 GeV

Measurement of Bose-Einstein Correlations in e+e- -> W+W- at root(s)=189GeV

We investigate Bose-Einstein correlations (BEC) in W-pair production at root(s)=189GeV using the L3 detector at LEP. We observe BEC between particles from a single W decay in good agreement with those from a light-quark Z decay sample. We investigate their possible existence between particles coming from different W's. No evidence for such inter-W BEC is found

Measurement of the Lifetime of the Tau Lepton

The tau lepton lifetime is measured with the L3 detector at LEP using the complete data taken at centre-of-mass energies around the Z pole resulting in tau_tau = 293.2 +/- 2.0 (stat) +/- 1.5 (syst) fs. The comparison of this result with the muon lifetime supports lepton universality of the weak charged current at the level of six per mille. Assuming lepton universality, the value of the strong coupling constant, alpha_s is found to be alpha_s(m_tau^2) = 0.319 +/- 0.015(exp.) +/- 0.014 (theory)

Standard Model Higgs Boson with the L3 Experiment at LEP

Final results of the search for the Standard Model Higgs boson are presented for the data collected by the L3 detector at LEP at centre-of-mass energies up to about 209 GeV. These data are compared with the expectations of Standard Model processes for Higgs boson masses up to 120 GeV. A lower limit on the mass of the Standard Model Higgs boson of 112.0 GeV is set at the 95 % confidence level. The most significant high mass candidate is a Hnunu event. It has a reconstructed Higgs mass of 115 GeV and it was recorded at root(s)=206.4 GeV