An invariant based transversely-isotropic constitutive model for unidirectional fibre reinforced composites considering the matrix viscous effects

Fibres Reinforced Polymers (FRPs) are found in several applications in aeronautics, space and in the automotive industry. These applications are exposed to loading conditions, including impact, which results in a complex mechanical response that is vital to accurately predict. This is particularly important for a new generation of thermoplastic-based composites. The model proposed in this work is an invariant-based approach to represent viscous effects in polymer composites. The model developed only requires two viscous parameters to calibrate the viscoelastic behaviour. A good correlation between the simulations and experimental data obtained in off- axis tests in tension and compression is obtained.Postprint (author's final draft

Effective simulation of the mechanics of longitudinal tensile failure of unidirectional polymer composites

An efficient computational model to simulate tensile failure of both hybrid and non-hybrid composite materials is proposed. This model is based on the spring element model, which is extended to a random 2D fibre packing. The proposed model is used to study the local stress fields around a broken fibre as well as the failure process in composite materials. The influence of fibre strength distributions and matrix properties on this process is also analysed. A detailed analysis of the fracture process and cluster development is performed and the results are compared with experimental results from the literature.Postprint (published version

An analytical model to predict stress fields around broken fibres and their effect on the longitudinal failure of hybrid composites

This paper presents an analytical model to predict the stress redistribution around broken fibres in hybrid polymer composites. The model is used under the framework of a progressive failure approach to study the load redistribution around breaks in hybrid composites. The outcomes of the model are validated by comparing it with a spring element model. Moreover, the approach is further used to study the tensile behaviour of different hybrid composites. The results obtained show that the load redistribution around breaks depends on the stiffness ratio between both fibres as well as the matrix behaviour considered and the hybrid volume fraction. Furthermore, the different material parameters have a large effect on the tensile behaviour, with an increase of ductility achieved if the failure process of the two fibres is gradual.Postprint (published version

Neonatal mortality rates, characteristics, and risk factors for neonatal deaths in Ghana:analyses of data from two health and demographic surveillance systems

BACKGROUND: Reducing neonatal mortality rates (NMR) in developing countries is a key global health goal, but weak registration systems in the region stifle public health efforts. OBJECTIVE: To calculate NMRs, investigate modifiable risk factors, and explore neonatal deaths by place of birth and death, and cause of death in two administrative areas in Ghana. METHODS: Data on livebirths were extracted from the health and demographic surveillance systems in Navrongo (2004-2012) and Kintampo (2005-2010). Cause of death was determined from neonatal verbal autopsy forms. Univariable and multivariable logistic regression were used to analyse factors associated with neonatal death. Multiple imputations were used to address missing data. RESULTS: The overall NMR was 18.8 in Navrongo (17,016 live births, 320 deaths) and 12.5 in Kintampo (11,207 live births, 140 deaths). The annual NMR declined in both areas. 54.7% of the births occurred in health facilities. 70.9% of deaths occurred in the first week. The main causes of death were infection (NMR 4.3), asphyxia (NMR 3.7) and prematurity (NMR 2.2). The risk of death was higher among hospital births than home births: Navrongo (adjusted OR 1.14, 95% CI: 1.03-1.25, p = 0.01); Kintampo (adjusted OR 1.76, 95% CI: 1.55-2.00, p < 0.01). However, a majority of deaths occurred at home (Navrongo 61.3%; Kintampo 50.7%). Among hospital births dying in hospital, the leading cause of death was asphyxia; among hospital and home births dying at home, it was infection. CONCLUSION: The NMR in these two areas of Ghana reduced over time. Preventing deaths by asphyxia and infection should be prioritised, centred respectively on improving post-delivery care in health facilities and subsequent post-natal care at home

Smoking and Ischemic Heart Disease Disparities Between Studies, Genders, Times, and Socioeconomic Strata

Large, unexplained, but possibly related disparities exist between heart disease risks observed in differing genders, educational levels, times, and studies. Such heart disease disparities might be related to cumulative tobacco smoke damage (smoke load) disparities that are overlooked in standard assessments of point smoking status. So, I reviewed possible relationships between smoke load and heart disease levels across genders, educational strata, years, and leading studies. Smoker heart disease risk assessments in the Nurses Health Study (Nurses), Cancer Prevention Study-II (CPS-II), and British Doctors studies were compared and related to their likely selection and misclassification biases. Relationships between smoke loads and United States (US) education- and gender-related heart disease mortality disparities were qualitatively assessed using lung cancer rates as a smoke load proxy. The high heart disease mortality risks observed in smoking Nurses in 1980–2004 and in less educated US women in 2001 were qualitatively associated with their higher smoke loads and lower selection and exposure misclassification biases than in the CPS-II and Doctors studies. Smoking-attributable heart disease death tolls and disparities extrapolated from mortality ratios from the CPS-II and Doctors studies may be substantial underestimates. Such studies appear to have compared convenience samples of light smokers to lighter smokers instead of comparing representative smokers to the unexposed. Further efforts to minimize smoke exposures and better quantify cumulative smoking-attributable burdens are needed

The impact of life tables adjusted for smoking on the socio-economic difference in net survival for laryngeal and lung cancer.

BACKGROUND: Net survival is a key measure in cancer control, but estimates for cancers that are strongly associated with smoking may be biased. General population life tables represent background mortality in net survival, but may not adequately reflect the higher mortality experienced by smokers. METHODS: Life tables adjusted for smoking were developed, and their impact on net survival and inequalities in net survival for laryngeal and lung cancers was examined. RESULTS: The 5-year net survival estimated with smoking-adjusted life tables was consistently higher than the survival estimated with unadjusted life tables: 7% higher for laryngeal cancer and 1.5% higher for lung cancer. The impact of using smoking-adjusted life tables was more pronounced in affluent patients; the deprivation gap in 5-year net survival for laryngeal cancer widened by 3%, from 11% to 14%. CONCLUSIONS: Using smoking-adjusted life tables to estimate net survival has only a small impact on the deprivation gap in survival, even when inequalities are substantial. Adjusting for the higher, smoking-related background mortality did increase the estimates of net survival for all deprivation groups, and may be more important when measuring the public health impact of differences or changes in survival, such as avoidable deaths or crude probabilities of death

Formal specification of multi-agent systems by using EUSMs

The behavior of e-commerce agents can be defined at different levels of abstraction. A formalism allowing to define them in terms of their economic activities, Utility State Machines, has been proposed. Due to its high level of abstraction, this formalism focuses on describing the economic goals rather on how they are achieved. Though this approach is suitable to specify the objectives of e-commerce agents, as well as to construct formal analysis methodologies, this framework is not suitable to define the strategic behavior of agents. In this paper we develop a new formalism to explicitly define the strategic behavior of agents in a modular way. In particular, we reinterpret the role of utility functions, already used in USMs in a more restrictive manner, so that they define strategic preferences and activities of agents. We apply the formalism to define the agents in a benchmark e-commerce agent environment, the Supply Chain Management Game. Since the strategic behavior of agents is located in a specific part of the formalism, different strategies can be easily considered, which enhances the reusability of the proposed specification

Aconitase B Is Required for Optimal Growth of Xanthomonas campestris pv. vesicatoria in Pepper Plants

The aerobic plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) colonizes the intercellular spaces of pepper and tomato. One enzyme that might contribute to the successful proliferation of Xcv in the host is the iron-sulfur protein aconitase, which catalyzes the conversion of citrate to isocitrate in the tricarboxylic acid (TCA) cycle and might also sense reactive oxygen species (ROS) and changes in cellular iron levels. Xcv contains three putative aconitases, two of which, acnA and acnB, are encoded by a single chromosomal locus. The focus of this study is aconitase B (AcnB). acnB is co-transcribed with two genes, XCV1925 and XCV1926, encoding putative nucleic acid-binding proteins. In vitro growth of acnB mutants was like wild type, whereas in planta growth and symptom formation in pepper plants were impaired. While acnA, XCV1925 or XCV1926 mutants showed a wild-type phenotype with respect to bacterial growth and in planta symptom formation, proliferation of the acnB mutant in susceptible pepper plants was significantly impaired. Furthermore, the deletion of acnB led to reduced HR induction in resistant pepper plants and an increased susceptibility to the superoxide-generating compound menadione. As AcnB complemented the growth deficiency of an Escherichia coli aconitase mutant, it is likely to be an active aconitase. We therefore propose that optimal growth and survival of Xcv in pepper plants depends on AcnB, which might be required for the utilization of citrate as carbon source and could also help protect the bacterium against oxidative stress

Israel: a rule of law against terrorism on the periphery of the democratic order

Fighting the threat of terrorism under the rule of law stands as one of the main challenges for democracies. The case of Israel (on which this contribution focuses) deserves special treatment, as it is a country that (even before its creation in 1948) is forced to fight against this scourge, because it recognizes itself as a democratic State and for inserting itself into a singular and complex geopolitical context in the convulsed region of the Middle East. Thus, it´s the paper´s objective to reflect on Israel´s fight against terrorism from the rule of law on the periphery of the democratic orderHacer frente a la amenaza del terrorismo en el marco del Estado de Derecho se erige en uno de los principales desafíos de las democracias. el caso de Israel (sobre el que se centra esta contribución) merece un tratamiento especial, ya que es un país que (incluso antes de su creación en 1948) se ve forzado a luchar contra dicho flagelo, por reconocerse como un Estado-Nación democrático y por insertarse en un contexto geopolítico singular y complejo en la convulsionada región del oriente medio. Así, es objetivo del artículo reflexionar en torno a la lucha de Israel contra el terrorismo desde el estado de derecho en la periferia del orden democrátic