Regional versus local drivers of water quality in the Windermere catchment, Lake District, United Kingdom: the dominant influence of wastewater pollution over the past 200 years

Freshwater ecosystems are threatened by multiple anthropogenic stressors acting over different spatial and temporal scales, resulting in toxic algal blooms, reduced water quality and hypoxia. However, while catchment characteristics act as a ‘filter’ modifying lake response to disturbance, little is known of the relative importance of different drivers and possible differentiation in the response of upland remote lakes in comparison to lowland, impacted lakes. Moreover, many studies have focussed on single lakes rather than looking at responses across a set of individual, yet connected lake basins. Here we used sedimentary algal pigments as an index of changes in primary producer assemblages over the last~200 years in a northern temperate watershed consisting of 11 upland and lowland lakes within the Lake District, United Kingdom, to test our hypotheses about landscape drivers. Specifically, we expected that the magnitude of change in phototrophic assemblages would be greatest in lowland rather than upland lakes due to more intensive human activities in the watersheds of the former (agriculture, urbanization). Regional parameters, such as climate dynamics, would be the predominant factors regulating lake primary producers in remote upland lakes and thus, synchronize the dynamic of primary producer assemblages in these basins. We found broad support for the hypotheses pertaining to lowland sites as wastewater treatment was the main predictor of changes to primary producer assemblages in lowland lakes. In contrast, upland headwaters responded weakly to variation in atmospheric temperature, and dynamics in primary producers across upland lakes were asynchronous. Collectively, these findings show that nutrient inputs from point sources overwhelm climatic controls of algae and nuisance cyanobacteria, but highlights that large-scale stressors do not always initiate coherent regional lake response. Furthermore, a lake’s position in its landscape, its connectivity and proximity to point nutrients are important determinants of changes in production and composition of phototrophic assemblages

Increasing frailty is associated with higher prevalence and reduced recognition of delirium in older hospitalised inpatients: results of a multi-centre study

Purpose: Delirium is a neuropsychiatric disorder delineated by an acute change in cognition, attention, and consciousness. It is common, particularly in older adults, but poorly recognised. Frailty is the accumulation of deficits conferring an increased risk of adverse outcomes. We set out to determine how severity of frailty, as measured using the CFS, affected delirium rates, and recognition in hospitalised older people in the United Kingdom. Methods: Adults over 65 years were included in an observational multi-centre audit across UK hospitals, two prospective rounds, and one retrospective note review. Clinical Frailty Scale (CFS), delirium status, and 30-day outcomes were recorded. Results: The overall prevalence of delirium was 16.3% (483). Patients with delirium were more frail than patients without delirium (median CFS 6 vs 4). The risk of delirium was greater with increasing frailty [OR 2.9 (1.8–4.6) in CFS 4 vs 1–3; OR 12.4 (6.2–24.5) in CFS 8 vs 1–3]. Higher CFS was associated with reduced recognition of delirium (OR of 0.7 (0.3–1.9) in CFS 4 compared to 0.2 (0.1–0.7) in CFS 8). These risks were both independent of age and dementia. Conclusion: We have demonstrated an incremental increase in risk of delirium with increasing frailty. This has important clinical implications, suggesting that frailty may provide a more nuanced measure of vulnerability to delirium and poor outcomes. However, the most frail patients are least likely to have their delirium diagnosed and there is a significant lack of research into the underlying pathophysiology of both of these common geriatric syndromes

Experimental Investigation and Numerical Simulation of C-Shape Thin-Walled Steel Profile Joints

The versatility of steel, its high resistance in relation to its low mass, as well as the easily accessible technology in the context of using recyclable materials and the low negative impact on the environment represent important arguments in using thin-walled steel profiles to make structures for buildings with a low height regime. This paper presents the results of an experimental program that investigated the behavior of three types of joints in a T-shape form made of thin-walled steel profiles to make shear wall panels or truss beam floors. Due to the small dimensions of the C-profiles of 89 × 41 × 12 × 1 mm, and of the technology of their joining, manufacturers prefer the hinged connections of elements with self-drilling screws. The purpose of the research presented in this paper is to assess the maximum capacity of the joints, the elastic and post-elastic behavior until failure, and also the mechanisms failure. The types of joints analyzed are commonly used in the production of structural systems for houses. The experimental program, which consisted of testing 5 specimens for each type of joint in tension (shear on screws), showed different behavior in terms of load-displacement. The experimental, tested models were analyzed by finite element simulations in an ANSYS nonlinear static structure with 3D solid models. The materials were defined by a bilinear true stress–strain curve obtained after some experimental tensile tests of the steel. The results of the experimental tests showed that the main failure mechanism is a yielding of the holes where the screws were mounted and a shearing of the profile walls. Adding an additional screw on each side increases the capacity of the joints, but not until a yield loss is obtained. In conclusion, it is shown that the solution is suitable for a low level of loading in a static manner; however, additional studies are necessary in order to develop and verify other solutions, thus improving the strength of the connection

Experimental Investigation and Numerical Simulation of C-Shape Thin-Walled Steel Profile Joints

The versatility of steel, its high resistance in relation to its low mass, as well as the easily accessible technology in the context of using recyclable materials and the low negative impact on the environment represent important arguments in using thin-walled steel profiles to make structures for buildings with a low height regime. This paper presents the results of an experimental program that investigated the behavior of three types of joints in a T-shape form made of thin-walled steel profiles to make shear wall panels or truss beam floors. Due to the small dimensions of the C-profiles of 89 × 41 × 12 × 1 mm, and of the technology of their joining, manufacturers prefer the hinged connections of elements with self-drilling screws. The purpose of the research presented in this paper is to assess the maximum capacity of the joints, the elastic and post-elastic behavior until failure, and also the mechanisms failure. The types of joints analyzed are commonly used in the production of structural systems for houses. The experimental program, which consisted of testing 5 specimens for each type of joint in tension (shear on screws), showed different behavior in terms of load-displacement. The experimental, tested models were analyzed by finite element simulations in an ANSYS nonlinear static structure with 3D solid models. The materials were defined by a bilinear true stress–strain curve obtained after some experimental tensile tests of the steel. The results of the experimental tests showed that the main failure mechanism is a yielding of the holes where the screws were mounted and a shearing of the profile walls. Adding an additional screw on each side increases the capacity of the joints, but not until a yield loss is obtained. In conclusion, it is shown that the solution is suitable for a low level of loading in a static manner; however, additional studies are necessary in order to develop and verify other solutions, thus improving the strength of the connection

Time History Analyses of a Masonry Structure for a Sustainable Technical Assessment According to Romanian Design Codes

Computer simulations are challenging in terms of modeling the appropriate behavior of brick masonry structures. These numerical simulations are becoming increasingly difficult due to several design code requirements considered for the technical assessment of brick masonry structures for rehabilitation. In Romania, many brick masonry structures have withstood powerful earthquakes during their lifetime and require rehabilitation works. This paper aims to further assess various simulation challenges regarding the boundary conditions of spandrels and masonry structural behavior. This paper presents a comparative numerical study of two different spandrel-piers scenarios: one considers the link between them as unaffected, and the other attempts to simulate the occurrence of damage by replacing the spandrel’s presence in the initial structure. The proposed model follows the “strong pier–weak spandrel model” and is aimed at practicing engineers. Models are computed with ordinary design software such as Robot Structural Analysis with 2D shells finite elements for masonry walls and, in a more complex manner, software such as Ansys with 3D solid finite elements. Time history analyses are carried out for three distinct accelerograms recorded in Romania. A comparison of the results acquired from these two models is presented and discussed. The purpose of this research is to highlight the importance of proper modeling of unreinforced brick masonry structures to optimize operational and maintenance practices

Environmental LCA of innovative reuse of all End-of-life tyre components in concrete

This paper presents the environmental life-cycle assessment of concrete mixtures containing materials recycled from End-of-Life tyres, i.e. rubber particles, sorted steel wires and polymer/textile cord fibres. This life-cycle assessment is based on ILCD and the ISO standards and considers “cradle to gate”, i.e. from extraction of raw materials, tyre-recycling and up to concrete production in ready mixture concrete plants. In total, 21 different concrete mixtures were analysed, including rubberised concrete and fibre reinforced concrete; mixtures with hybrid fibres were also considered (i.e. reinforced with both recycled and manufactured fibres). The results of this LCA show that, for a functional unit of 1 m3 of concrete, cement is the main parameter contributing to the inventory of the examined concrete mixtures; this indicates the need of utilising “low energy” and low calcination cements to minimise their environmental impact. When performance-based functional units are considered in the LCA, the results highlight the importance of using these recycled materials in structural concrete applications that fully utilise the specific mechanical characteristics of each material, as demonstrated for rubberised concrete and steel fibre-reinforced concrete mixtures

Experimental Investigations on the Long Term Material Properties of Rubberized Portland Cement Concrete

The paper presents the results of a research work aimed at assessing the long-term strength and elastic properties of rubberized concrete. The parameters of the research were the rubber replacement of fine aggregates and the age of testing the specimens. Compressive and splitting tensile strength of concrete cylinders were obtained at the age of 5 years, coupled with the static and dynamic modulus of elasticity of all concrete specimens. Additionally, the material damping coefficient was assessed by means of non-destructive tests. The density of the rubberized concrete decreases with the percentage replacement of natural sand by rubber aggregates. A significant drop in the values of density after 5 years was observed for specimens made with rubberized concrete. The static and the dynamic moduli of elasticity decrease with the increase in rubber content. A similar trend is observed for the compressive and tensile splitting strength

Influence of Concrete Strength Class on the Long-Term Static and Dynamic Elastic Moduli of Concrete

Construction materials, among which concrete is by far the most used, have followed a trend of continuously increasing demand in real estate. A relatively small number of research works have been published on the long-term material properties of concrete in comparison to studies reporting their findings at standard curing ages of 28 days. This is due, in part, to the length of time one must wait until the intended age of concrete is reached. The present paper contributes to filling this gap of information in terms of the strength and dynamic elastic properties of concrete. The dynamic modulus of elasticity may be used to assess the static modulus of elasticity (Young’s modulus), a key property used during the design stage of a structure, in a non-destructive manner. This paper presents the results obtained from laboratory tests on the long-term (6 years) characterization of concrete from the point of view of dynamic shear and longitudinal moduli of elasticity, dynamic Poisson’s ratio, static modulus of elasticity, compressive and tensile splitting strengths, and their change depending on the concrete strength class