Summary
Given that endothelial dysfunction precedes atherosclerotic cardiovascular disease, exploring the parameters that modify postprandial flow‐mediated dilation (FMD) is important for public ...health. The objectives of the study are to estimate the population effect of meal ingestion on FMD and to determine how the effect varied based on patient characteristics and modifiable methodological features. Articles published before June 2015 were located using MEDLINE, PubMed and Web of Science. One hundred fifty‐four effects were derived from 78 articles involving 2,548 subjects were selected. Included articles required measurement of FMD in adults before and after meal ingestion. Effects were analysed using an unstandardized mean gain random effects model, and significant moderators were analysed using meta‐regression. Meal consumption significantly reduced FMD by a heterogeneous mean effect size delta (Δ) of −2.03 (95% CI: −2.28, −1.77), an ~2% reduction in FMD. FMD reductions were larger among normal weight individuals, males, those with a cardio‐metabolic disorder, those with elevated baseline FMD, and individuals with impaired glucose tolerance at baseline. Macronutrient meal ingestion significantly reduced FMD, an effect that was moderated by body mass index, sex and two‐way interactions between disease status and both baseline FMD and baseline blood glucose levels.
•The stiffness of cold asphalt mixtures (CAM) containing CDW as aggregate were studied.•CAMs with CDWA frequently achieved higher stiffness than control mixes.•CAMs with CDWA were less temperature ...susceptible and more fatigue resistant.•CAMs with CDWA were more complicated to design.•Clear dependency of stiffness on the compaction process (static and gyratory).
The stiffness of cold asphalt mixtures (CAM) with 100% recycled construction and demolition waste aggregates (CDWA) was studied from three different points of view: the indirect tensile stiffness modulus (ITSM), the dynamic modulus at different temperatures and frequencies and the correlation between them. It was found that CAM with CDWA frequently achieved higher stiffness than control mixes using natural aggregate (NA), but that they required significantly higher bitumen and water contents. They were less temperature susceptible, therefore potentially more fatigue resistant, but more complicated to design. Finally, a clear dependency on the compaction process (static and gyratory) was also found.
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 relation to ballast field conditions. Results showed that overall bitumen stabilisation improved ballast resistance to permanent deformation by enhancing stiffness and damping properties. Scenarios with higher dosage of bitumen emulsion, higher viscosity, quicker setting behaviour, and harder base bitumen seem to represent the most desirable conditions to achieve enhanced in-field performance.
Shakedown of asphalt pavements considering temperature effect Liu, S.; Wang, J.; Yu, H. S. ...
International journal of pavement engineering/The International journal of pavement engineering,
04/16/2022, Letnik:
23, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Shakedown limit has been perceived as a useful guidance in pavement structure design against rutting. However, temperature, as one key factor influencing the shakedown limit of asphalt pavements, has ...barely been considered. In this paper, the shakedown phenomenon was first identified from wheel tracking tests for a pavement structure consisting of a dense bituminous macadam layer and a granular layer at 40°C. Based on a previously developed shakedown approach and the material elastic and plastic properties obtained through a series of tests, lower-bound shakedown limits of the layered system were determined and compared with the wheel tracking test results. Following that, an empirical relation between temperature and cohesion of asphalt mixture was suggested. A temperature-dependent shakedown approach was then proposed which can quickly obtain the shakedown limits of asphalt pavements over a range of temperatures. Results show that the shakedown limits decrease markedly with increasing temperature, accompanied by a shift of the failure mode from a granular layer failure to an asphaltic layer failure. One effective and economic way to enhance the pavement performance under high temperature is improving shear strength properties of asphalt mixtures. By using this method, pavement stability against rutting can be evaluated efficiently at any temperature.
The evaluation of fundamental mechanical properties of bitumen is vital to construct long-term performing pavements. This research evaluates cohesive bond strength of bitumen and mastics using ...compression pull-off test (CPOT). The results show problems in the common interpretation of load-displacement curves. A discussion is made on fibrillary nucleation in binder. The curing for 24 h is sufficient for the development of the cohesive bond. Furthermore, longer conditioning is needed to evaluate the moisture damage using aluminium plates. Bitumen source, grade, filler content, and loading rate affect the pull-off strength (POS). Ageing increases POS and shifts the failure mode towards brittle. The type of filler does not affect POS after short-term ageing. The moisture conditioning reduces the POS and results in a mixed to adhesive failure with increased variability in results. The aggregate plates are necessary for detailed moisture damage evaluation. The use of re-used aggregate substrate is found to be ineffective.
A 3-year-old, intact female mixed-breed dog, weighing 7 kg, was presented with generalised swelling of the tongue, leading to impaired deglutition and episodes of dyspnoea. From the age of 2 years, ...the dog had been under immunosuppressive therapy due to atopic dermatitis.
Multiple nodular lesions at the apex of the tongue were noted as well as mandibular and retropharyngeal lymph node enlargement. Serum biochemistry results showed inflammatory changes. The results of several biopsies taken over 7 months indicated persistent pyogranulomatous and necrotising glossitis despite ongoing antimicrobial treatment, first with amoxicillin/clavulanic acid and then pradofloxacin. No foreign material, acid-fast bacteria or fungal hyphae were detected throughout. The final diagnosis of Mycobacterium avium subsp. hominissuis (Mah) was reached after PCR and bacterial culture were carried out on the third biopsy sample. Therapy was initiated with rifampicin, clarithromycin and doxycycline, leading to complete remission of the lesions.
Severe chronic pyogranulomatous and necrotising glossitis associated with infection by Mah.
This report describes challenges in the diagnosis and therapy of a localised Mah infection in an iatrogenically immunocompromised dog. Successful treatment was only achieved with a specific combination of antibiotics administered long-term.
AF: Acid-fast; ALP: Alkaline phosphatase; CT: Computed tomography; MAC: Mycobacterium avium complex; Mah: Mycobacterium avium subsp. hominissuis
Roads as vital public assets are the backbone for transportation systems and support constant societal development. Recently, data-driven technologies such as digital twins and especially machine ...learning have shown great potential to maintain the service level of the existing road infrastructure by accurate future condition modelling and optimal maintenance treatment recommendations. However, the pavement community suffers from inadequate data and errors experienced in data collection, which unavoidably limits machine learning performance. In addition, focusing solely on data without considering the underlying physical behaviour remains as a challenge for the practical implementation of machine learning. To this end, this study provides a machine learning based approach to predict road rutting taking into account the machine learning uncertainties. The US Long-Term Pavement Performance public database has been used as the main data source while supplementary synthetic data was added using Finite Element simulations based on physics. The obtained results indicate that adding extra simulation data improved the model’s short-term prediction accuracy by 4.4% and reduced the long-term prediction uncertainty by 6.76%. The approach could potentially mitigate the issue of lack of data and the uncertainties around the data collected, by integrating existing understanding of pavement physical behaviour into the machine learning modelling pipeline.
This paper presents an evaluation of the behaviour of geogrid-reinforced railway ballast. Experimental large box pull-out tests were conducted to examine the key parameters influencing the ...interaction between ballast and the geogrid. The experimental results demonstrated that the triaxial geogrid outperforms the biaxial geogrid and the geogrid aperture size is more influential than rib profile and junction profile. The discrete element method (DEM) has then been used to model the interaction between ballast and geogrid by simulating large box pull-out tests and comparing with experimental results. The DEM simulation results have been shown to provide good predictions of the pull-out resistance and reveal the distribution of contact forces in the geogrid-reinforced ballast system. Therefore, the calibrated geogrid model and the use of clumps to model ballast particles hold much promise for investigating the interaction between geogrids and ballast and therefore optimising performance.
Cold recycled bound materials (CRBMs) provide an economic and environmental advantage for pavements since they decrease energy and raw material consumption. However, design methods for airfield ...pavements do not include key CRBM properties. In this paper an empirical-mechanistic method is used to study airfield pavement design with CRBM in order to develop design guidance. The aim of the paper is to obtain the inputs related to material properties needed for use in this method. For this purpose, CRBM containing reclaimed asphalt, with fly ash, cement and foamed bitumen as stabilising agents, was characterised. The methodology included indirect tensile stiffness modulus (ITSM) and indirect tensile fatigue tests (ITFT) in strain control mode. The inputs needed for a pavement design analysis with CRBM were then obtained. The results showed the importance of further study on CRBM fatigue to understand the behaviour of these mixes under cyclic loading.
PDF
