Rehabilitation of La Nerthe Tunnel on Paris-Marseille High-Speed Railway Line

The La Nerthe tunnel is located on the Paris-Marseille railway line under the Étoile mountain range. This 4638 m long double track tunnel was built at the middle of 19th century under a maximum cover of 180 m and currently is used as part of the high-speed railway line (TGV). This masonry tunnel with hard limestone blocks at the sidewalls and bricks at the crown passes through marl, gypsum and limestone zones. A major fault with accompanying extensive tectonic deformations cuts across the tunnel axis. The in-situ stress tests performed on the new high-speed rail line in the zone with intense tectonic fractures highlighted the tectonic residual stresses with very high lateral earth pressure coefficients (k0). The La Nerthe tunnel underwent ovalization deformation with excessive displacement at the springline, and pinching and bursting of the bricks at the crown. In this paper, the geological context and the damage to the tunnel lining are described in detail. The theoretical tunnel profile has been compared with the actual real section in order to determine the size and the shape of the lining deformation. The initialization of the existing stress field in the tunnel masonry lining using the original excavation and support methods and also a simplified approach for considering the time effect has been explained in detail. Finite element analyses have allowed an understanding of the possible causes of the observed damages and to propose an adequate reinforcement method. The applied rehabilitation system and the constraints of work in this busy mainline railway tunnel have been discussed in detail

Homologation of carboxylic acids by arndt-eistert reaction under ultrasonic waves

International audienc

Detection of T wave beta-to-beat variations prior to ventricular arrythmias onset in ICD-stored intracardiac electrograms: the endocardial T-wave alternans study (ETWAS)

International audienceBackground: The aim of the Endocardial T-Wave Alternans Study was to prospectively assess thepresence of T-wave alternans (TWA) or beat-to-beat repolarization changes on implantable cardioverter-defibrillator (ICD)-stored electrograms (EGMs) immediately preceding the onset of spontaneous ventriculartachycardia (VT) or fibrillation (VF). Methods: Thirty-seven VT/VF episodes were compared to 116 baseline reference EGMs from the same57 patients. A Bayesian model was used to estimate the T-wave waveform in each cardiac beat and a setof 10 parameters was selected to segment each detected T wave. Beat-by-beat differences in each T-waveparameter were computed using the absolute value of the difference between each beat and the followingone. Fisher criterion was used for determining the most discriminant T-wave parameters, then top-Mranked parameters yielding a normalized cumulative Fisher score>95% were selected, and analysis wasapplied on these selected parameters. Simulated TWA EGMs were used to validate the algorithm. Results: In the simulation study, TWA was detectable even in the case of the smallest simulatedalternans of 25μV. In 13 of the 37 episodes (35%) occurring in nine of 16 patients, significant largerbeat-to-beat variations before arrhythmia onset were detected compared to their respective references(median one positive episode per patient). Parameters including the T-wave apex amplitude seem themore discriminant parameters.Conclusions:Detection of beat-by-beat repolarization variations in ICD-stored EGMs is feasible ina significant subset of cases and may be used for predicting the onset of ventricular arrhythmias

Impact of Neuroeffector Adrenergic Receptor Polymorphisms on Incident Ventricular Fibrillation During Acute Myocardial Ischemia

Background Cardiac adrenergic receptor gene polymorphisms have the potential to influence risk of developing ventricular fibrillation (VF) during ST‐segment‐elevation myocardial infarction, but no previous study has comprehensively investigated those most likely to alter norepinephrine release, signal transduction, or biased signaling. Methods and Results In a case–control study, we recruited 953 patients with ST‐segment‐elevation myocardial infarction without previous cardiac history, 477 with primary VF, and 476 controls without VF, and genotyped them for ADRB1 Arg389Gly and Ser49Gly, ADRB2 Gln27Glu and Gly16Arg, and ADRA2C Ins322‐325Del. Within each minor allele‐containing genotype, haplotype, or 2‐genotype combination, patients with incident VF were compared with non‐VF controls by odds ratios (OR) of variant frequencies referenced against major allele homozygotes. Of 156 investigated genetic constructs, 19 (12.2%) exhibited significantly (P<0.05) reduced association with incident VF, and none was associated with increased VF risk except for ADRB1 Gly389 homozygotes in the subset of patients not receiving β‐blockers. ADRB1 Gly49 carriers (prevalence 23.0%) had an OR (95% CI) of 0.70 (0.49–0.98), and the ADRA2C 322–325 deletion (Del) carriers (prevalence 13.5%) had an OR of 0.61 (0.39–0.94). When present in genotype combinations (8 each), both ADRB1 Gly49 carriers (OR, 0.67 [0.56–0.80]) and ADRA2C Del carriers (OR, 0.57 [0.45– 0.71]) were associated with reduced VF risk. Conclusions In ST‐segment‐elevation myocardial infarction, the adrenergic receptor minor alleles ADRB1 Gly49, whose encoded receptor undergoes enhanced agonist‐mediated internalization and β‐arrestin interactions leading to cardioprotective biased signaling, and ADRA2C Del322‐325, whose receptor causes disinhibition of norepinephrine release, are associated with a lower incidence of VF. Registration URL: https://clinicaltrials.gov; Unique identifier: NCT00859300

Prediction of ventricular arrhythmias in patients with a spontaneous brugada type 1 pattern: the key is in the electrocardiogram

There is currently no reliable tool to quantify the risks of ventricular fibrillation or sudden cardiac arrest (VF/SCA) in patients with spontaneous Brugada type 1 pattern (BrT1). Previous studies showed that electrocardiographic (ECG) markers of depolarization or repolarization disorders might indicate elevated risk. We aimed to design a VF/SCA risk prediction model based on ECG analyses for adult patients with spontaneous BrT1