Search results for "RAIL"
showing 10 items of 699 documents
Arrays in rays: terminal addition in echinoderms and its correlation with gene expression
2005
Summary The echinoderms are deuterostomes that superimpose radial symmetry upon bilateral larval morphology. Consequently, they are not the first animals that come to mind when the concepts of segmentation and terminal addition are being discussed. However, it has long been recognized that echinoderms have serial elements along their radii formed in accordance with the ocular plate rule (OPR). The OPR is a special case of terminal growth, forming elements of the ambulacra that define the rays in echinoderms. New elements are added at the terminus of the ray, which may or may not be marked by a calcified element called the terminal plate (the “ocular” of sea urchins). The OPR operates in eve…
Study of the role of BCL-XL in healthy aging and frailty prevention
2022
Aging is defined as an intrinsic, progressive, deleterious and inevitable multifactorial phenomenon that occurs as a result of the gradual accumulation of damage at cellular and molecular levels. Due to the recent discovery of BCL-XL being overexpressed in peripheral blood mononuclear cells from centenarians, a new approach has emerged to investigate the BCL-XL function in healthy aging. The major goal of this thesis is to study the role of BCL-XL in frailty and healthy aging in transgenic mice overexpressing a human form of BCL-XL in T cells. For this, we used the heterozygous transgenic mice from Cg-Tg(LCKprBCL2L1)12Sjk/J strain, which express the human BCL-XL cDNA sequence in all thymocy…
An Easy Assessment of Frailty at Baseline Independently Predicts Prognosis in Very Elderly Patients With Acute Coronary Syndromes.
2017
Background: Information about the impact of frailty in patients with acute coronary syndromes (ACS) is scarce. No study has assessed the prognostic impact of frailty as measured by the FRAIL scale in very elderly patients with ACS. Methods: The prospective multicenter LONGEVO-SCA registry included unselected patients with ACS aged 80 years or older. A comprehensive geriatric assessment was performed during hospitalization, including frailty assessment by the FRAIL scale. The primary endpoint was mortality at 6 months. Results: A total of 532 patients were included. Mean age was 84.3 years, 61.7% male. Most patients had positive troponin levels (84%) and high GRACE risk score values (mean 16…
Bitumen stabilized ballast: a potential solution for railway track-bed
2016
Railway ballast degradation under dynamic loads progressively leads to loss of mechanical performance and geometry of the track, so that maintenance interventions are frequently needed. In order to system- atically avoid this issue, recently solutions have been proposed to reinforce track-bed by using polyur- ethane and/or resins as well as asphalt layers among others. Nonetheless, their main limitations are related to the high initial cost and low productivity. To cope with these limitations, in this study, bitumen stabilized ballast (BSB) is proposed as a new solu- tion for ballast stabilization. This method aims at improving durability and reducing settlement by mod- ifying both stiffnes…
A Dynamic Model of Ballasted Rail Track with Bituminous Sub-Ballast Layer
2012
AbstractThe bituminous sub-ballast layer within the ballasted rail track allows some mechanical and environmental advantages. An analytical model of a ballasted rail track with sub-ballast layer has been proposed by considering the rail as viscous-elastic continuous beam discretely supported, at four levels of elasticity.The model was used to compare the mechanical performance of both ballasted track with and without bituminous sub-ballast layer. The results confirmed that the bituminous sub-ballast layer reduces the dynamic forces on the ground and achieves the technical objectives as reduction of ground borne vibrations and increase of the design life of the rail track.
Optimización de las propiedades de emulsión de betún para la estabilización de balasto
2017
Ballasted track, while providing economical and practical advantages, is associated with high costs and material consumption due to frequent maintenance. More sustainable alternatives to conventional ballasted trackbeds should therefore aim at extending its durability, particularly considering ongoing increases in traffic speed and loads. In this regard, the authors have investigated a solution consisting of bitumen stabilised ballast (BSB), designed to be used for new trackbeds as well as in reinforcing existing ones. This study presents the idea behind the technology and then focuses on a specific part of its development: the optimisation of bitumen emulsion properties and dosage in relat…
Novel performance-based technique for predicting maintenance strategy of bitumen stabilised ballast
2018
Abstract Despite being the most used worldwide, railway ballasted tracks presents high maintenance cost related to ballast settlement and particle degradation. With the aim of reducing life cycle costs, bitumen stabilised ballast (BSB) has been recently proposed as a relatively cheap alternative maintenance solution to be applied to existing tracks. This study aims at assessing the potential advantages of this technology, defining a novel maintenance strategy of traditional ballasted track-beds. A protocol for the application of the BSB technology and its associated maintenance strategy is defined. To estimate minor and major maintenance operations of BSB scenario in comparison to tradition…
Optimization of the Mix-Design System for the Sub-ballast Railroad
2017
Bituminous sub-ballast is an alternative solution to the unbound granular sub-ballast used in the railway track due to several benefits that it can provide. Indeed, it contributes to maintain the moisture content in the subgrade unchanged during all year. This decreases the subgrade deterioration process. Moreover, the presence of bituminous sub-ballast can also reduce vertical stiffness variations on the track; it can have a positive effect in the maintenance needs at transition sections (bridge-embankment) and in the attenuation of the vibrations induced by the rail traffic. Despite the importance of the presence of the bituminous sub-ballast to conceive the construction and/or rehabilita…
High Performance Bi-Block Sleeper for Improvement the Performances of Ballasted Railway Track
2012
Abstract This article focuses on the performance of an innovative railway sleeper, recently patented in Italy and called “HP-BB” (High Performance Bi-Block sleeper), under different efficiency conditions of the ballast. The research is carried out through a comparative assessment of traditional mono- and bi-block sleepers, evaluating the lateral resistance of the single sleeper thought as independent of the other constituents of the track.
A New High-Efficiency Procedure for Aggregate Gradation Determination of the Railway Ballast by Means Image Recognition Method
2013
Abstract The mechanical characteristics of the railway superstructure are related to the properties of the ballast, and especially to the particle size distribution of its grains. Under the constant stress-strain of carriages, the ballast can deteriorate over time, and consequently it should properly be monitored for safety reasons. The equipment which currently monitors the railway superstructure (like the Italian diagnostic train Archimede) do not make any “quantitative” evaluation of the ballast. The aim of this paper is therefore to propose a new methodology for extracting railway ballast particle size distribution by means of the image processing technique. The procedure has been teste…