Background. We endeavored to construct a simple score based entirely on epidemiological and clinical variables that would stratify patients who require hospital admission because of ...community-acquired pneumonia into groups with a low or high risk of developing bacteremia. Methods. Derivation and internal validation cohorts were obtained by retrospective analysis of a database that included 3116 consecutive patients with community-acquired pneumonia from 2 university hospitals. Potential predictive factors were determined by means of a multivariate logistic regression equation applied to a cohort consisting of 60% of the patients. Points were assigned to significant parameters to generate the score. It was then internally validated with the remaining 40% of patients and was externally validated using an independent multicenter cohort of 1369 patients. Results. The overall rates of bacteremia were 12%-16% in the cohorts. The clinical probability estimate of developing bacteremia was based on 6 variables: liver disease, pleuritic pain, tachycardia, tachypnea, systolic hypotension, and absence of prior antibiotic treatment. For the score, 1 point was assigned to each predictive factor. In the derivation cohort, a cutoff score of 2 best identified the risk of bacteremia. In the validation cohorts, rates of bacteremia were <8% for patients with a score ⩽1 (43%-49% of patients), whereas blood culture results were positive in 14%-63% of cases for patients with a score ⩾2. Conclusions. This clinical score, based on readily available and objective variables, provides a useful tool to predict bacteremia. The score has been internally and externally validated and may be useful to guide diagnostic decisions for community-acquired pneumonia.
The combined effect of moisture and mechanical loading on asphalt mixtures has been recognized as one of the main causes of premature deterioration of flexible pavements. This paper presents a ...micromechanical model of moisture-induced damage in asphalt mixtures. The model couples the effect of moisture diffusion and mechanical loading to quantify the level of damage within the mixtures. The mechanical properties of the materials are defined as a function of the amount of moisture content. The cohesive zone modeling technique is used to simulate adhesive damage at the aggregate-mastic interfaces. Damage is evaluated based on the location and time for crack initiation and propagation at the aggregate-mastic interfaces and on the level of strains and stresses within the bulk of the mastic. Results show that micromechanical models provide a better understanding of moisture damage mechanisms in asphalt mixtures and can guide the development of continuum damage models.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Thanks to the industrial and technological development, man has managed to travel fast, to take advantage of artificial light in the absence of natural light, to enjoy the air-conditioned rooms in ...case of discomfort and much more. The engine of these processes is energy, which needs to be considered the production phases. The world's energization began mainly through fossil sources, but due to the thinning of the atmospheric ozone layer and the overall increase in the concentration of CO2over the years, due to anthropogenic and non-human causes, which led to overheating global, global decarbonisation has become necessary. It is essential to encourage the development of low-carbon and energy-efficient technologies. This document shows the current problems, in terms of environmental impact, and the possible solutions applied and applicable in the future to counteract the increase in average temperature of 2 degrees by 2050. The main point is to make buildings less energetic with technological devices, addressing their honors and obligations.
This paper analysed and verified an existing block stone pavement in an urban shared area. Fatigue and rutting verification was performed respectively for bound and unbound pavement materials using ...analytical curves available in the literature. The commercial finite element (FE) software Abaqus® was used to calculate the response of the pavement when subjected to different loading, construction and geometrical configurations (i.e. type of analysis, shape and size of meshes, boundary conditions, and bonding contacts between the pavements layers). At the end of this study, a static model of a structure with hexahedral blocks having sides of 0.02 m, with full bonded layers and restrained horizontal displacements on the model sides, was implemented to evaluate the maximum tensile stress induced in a block when the load is applied at its centre. This analysis highlighted the need for rigorous criteria for a correct design, in order to avoid inappropriate and expensive use of road materials.
Erosion of the base layers in rigid pavements is a complex hydro-mechanical process that rapidly reduces the structural integrity of these structures. This research revisits a vertical shaking table ...testing method to characterise the erosion susceptibility of the materials used on base layers in rigid pavements. The procedure consists of applying a vertical vibration to a cylindrical sample of the material under evaluation, which is partially immersed in water in a cylindrical metallic container with a high-strength concrete base. The vertical movement of the sample causes a radial flow of water on its base, which induces high shear forces that eventually erode the bottom of the sample. The volumetric loss of material from the testing sample under different water velocities and pressure conditions is used to quantify its susceptibility to erosion. After presenting the theoretical principles and the numerical formulation of the hydro-mechanical erosion processes occurring in this test, the experimental method was applied to characterise the erosion susceptibility of five different materials. The results suggest that the vertical shaking experimental technique is more versatile and accurate in quantifying the erosion susceptibility of base materials than available standardised tests.
•We assessed the fracture properties of an asphalt mixture (HMA) and its mortar (FAM)•SCB tests were conducted at 6 different loading rates on both HMA and FAM.•A scan technique was used to compute ...the area of the cracked zone of both materials.•Cracked area and resistance to crack propagation were not dependent on loading rate.•Other fracture factors were loading-rate dependent and different between HMA and FAM.
Proper fracture characterization of Hot Mix Asphalt (HMA) is crucial to enhance the durability of pavement structures. This work evaluates the influence of the loading rate on the fracture behaviour of a typical dense-graded asphalt mixture and its correspondent mortar or Fine Asphalt Mixture (FAM). Semi-Circular Bending (SCB) tests were conducted under intermediate temperature (24 ± 1 °C), and six different loading rates (i.e., 0.1, 0.5, 5, 10, 25, 50 mm/min). The results show that neither the three-dimensional cracked surface area of the fracture zone of the FAM and HMA samples nor the resistance to crack propagation of the materials were loading rate-dependent, whereas its fracture energy, strength and stiffness were sensitive to this testing condition. Significant differences were also observed in the magnitudes of all cracking parameters within the full mixture and its mortar, as expected, except for the stiffness of the materials.
Both β-amyloid (Aβ) peptides and oxidative stress conditions play key roles in Alzheimer’s disease. Hemin contributes to the development of the disease as it possesses redox properties and its level ...increases in pathological conditions or traumatic brain injuries. The aim of this work was to deepen the investigation of the reactivity of the hemin–Aβ16 complex, considering its ability to catalyze oxidation and nitration reactions. We performed kinetic studies in the presence of hydrogen peroxide and nitrite with phenolic and catechol substrates, as well as mass spectrometry studies to investigate the modifications occurring on the peptide itself. The kinetic constants were similar for oxidation and nitration reactions, and their values suggest that the hemin–Aβ16 complex binds negatively charged substrates with higher affinity. Mass spectrometry studies showed that tyrosine residue is the endogenous target of nitration. Hemin degradation analysis showed that hemin bleaching is only partly prevented by the coordinated peptide. In conclusion, hemin has rich reactivity, both in oxidation and nitration reactions on aromatic substrates, that could contribute to redox equilibrium in neurons. This reactivity is modulated by the coordination of the Aβ16 peptide and is only partly quenched when oxidative and nitrative conditions lead to hemin degradation.
•We subjected one hot mix asphalt (HMA) to multiple wetting–drying cycles.•The wetting–drying cycles were conducted through the vapour equilibrium technique.•|E*| was computed at each saturation ...level using the HCT-AM.•The wetting–drying cycles caused an irreversible degradation in |E*|.•This study shows the influence of partial saturation in the response of HMAs.
The top asphalt layers of pavement structures are subjected to loading demands and multiple environmental factors. Even though existing studies on moisture damage in asphalt mixtures have demonstrated the deleterious effects of water on different mechanical properties of these materials, the impact caused by changes in the partial saturation during the application of wetting–drying cycles on the linear viscoelastic properties of the mixture is an unexplored field. This study quantifies, for the first time, the changes in these properties (i.e., dynamic modulus, |E*|, and phase angle, ϕ) of a conventional asphalt mixture subjected to multiple wetting–drying moisture vapour cycles. The testing specimens were conditioned at five different relative humidity (RH) environments that were increased (wet path) or reduced (dry path) gradually, causing different saturation levels within their microstructures. The magnitude of |E*| and ϕ of the specimens was measured after reaching a steady state condition at each individual RH environment. In total, the specimens were subjected to five wetting–drying cycles and to a total of 41 dynamic modulus tests. The results corroborate that the degree of saturation impacts the linear viscoelastic properties of the mixture and show the irreversible effect of wetting–drying cycles on these properties. Since the dynamic modulus is an input parameter in the design of flexible pavements, the results also suggest that the degradation of this property due to changes in the partial saturation under field conditions could be included as part of existing mechanistic-empirical design methodologies.
Determinar la asociación entre las dimensiones de las estructuras craneofaciales de adolescentes y la presencia de TTM. Material y Métodos Estudio de casos y controles. Se evaluaron 46 pacientes de ...10 a 16 años de edad con sus respectivas radiografías laterales de cráneo (23 casos y 23 controles, pareados por edad y sexo). Se aplicaron los Criterios Diagnósticos para la Investigación de los TTM (CDI/TTM) para establecer los casos y los controles por investigador estandarizado. Resultados La comparación entre casos y controles de las estructuras craneofaciales, no demostró diferencias significativas, sin embargo la altura facial inferior, el eje facial y el plano mandibular fueron ligeramente superiores en el grupo de los casos. En el análisis de ANOVA de dos vías, (diagnóstico y edad), la convexidad facial presentó diferencias entre los adolescentes varones con y sin Trastornos temporomandibulares (p=0,002). Conclusión Las estructuras craneofaciales no se asocian con el diagnóstico de TTM en los adolescentes, sin embargo se presentan cambios en las relaciones maxilomandibulares, (ubicación anterior del maxilar con respecto a la mandíbula) que provocan un patrón esquelético Clase II y una forma alargada de la cara.
This chapter explores the evolution of public lighting, tracing its historical development from the early days of illumination to contemporary times. It highlights the contemporary significance of ...public lighting in meeting regulatory standards for illumination, emphasizing the fundamental role of LED technology. LED technology not only ensures compliance with lighting regulations but also significantly reduces network power consumption, thereby mitigating environmental pollution compared to traditional discharge lamps. Furthermore, this chapter underscores the transformative shift in the role of modern lighting systems, which have evolved into multifunctional hubs for the integration of value-added services. These services encompass a wide range of applications, including surveillance cameras, smart parking systems, and electric vehicle charging stations, thereby enhancing the overall functionality and sustainability of urban environments.
PDF
