625 research outputs found

    Uniform materials and the multiplicative decomposition of the deformation gradient in finite elasto-plasticity

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    In this work we analyze the relation between the multiplicative decomposition F=FeFp\mathbf F=\mathbf F^{e}\mathbf F^{p} of the deformation gradient as a product of the elastic and plastic factors and the theory of uniform materials. We prove that postulating such a decomposition is equivalent to having a uniform material model with two configurations - total ϕ\phi and the inelastic ϕ1\phi_{1}. We introduce strain tensors characterizing different types of evolutions of the material and discuss the form of the internal energy and that of the dissipative potential. The evolution equations are obtained for the configurations (ϕ,ϕ1)(\phi,\phi_{1}) and the material metric g\mathbf g. Finally the dissipative inequality for the materials of this type is presented.It is shown that the conditions of positivity of the internal dissipation terms related to the processes of plastic and metric evolution provide the anisotropic yield criteria

    Architectural self-fabrication

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    The paper will focus on the role of computational design and digital fabrication in the processes of urban and architectural self-regeneration of existing infrastructures and buildings. The Architectural Fabrication research agenda takes inspiration from some of the concepts mentioned in Christopher Alexander’s essay ‘Systems generating systems’ (1968). It aims at introducing ways in which systems thinking and computer aided manufacturing can be most directly applied to the built environment. Hacking architectural spaces, by evolving their genetic spatial and structural codes, is developing the idea of optimizing resources involving inhabitants rather than generating other top down architectural solutions. During the last decades (starting from the book of Mario Carpo, ‘The Digital Turn in Architecture’) the digital shift in architectural design has generated a new discipline with the aim to define an innovative way to bridge the notion of nature with the one of teknù. From such a cultural milieu many research agenda were focusing on the concepts of morphogenesis and evolutionary thinking inspired by the work of French philosophers Gilles Deleuze and Felix Guattari based on the theory of complex systems. Despite this interest in bridging an evolutionary approach with the notion of emergent technologies in architecture (well described in the book ‘The Architecture of Emergence’ of Michael Weinstock) only a very few researchers have investigated on the potential of computational design as a driver for the ecological rehabilitation of existing infrastructures. As a matter of fact, the computational designers were so worried to claim for a new aesthetical identity of their discipline while a new opportunity was emerging for applying this evolutionary approach in order to hack existing structures. The idea of living infrastructures is related to the possibility of developing contextual algorithms in order to customize standard solutions with a post-human process that creates diversified spatial configurations out of very rigid organizational systems. Therefore, the paper will also talk about the Hacking Gomorra project as a possible paradigm of experimenting a 3D printing protocol for the environmental rehabilitation of a mega-structural housing building in Naples (Italy)

    Superconductivity in Sr2RuO4-Sr3Ru2O7 eutectic crystals

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    Superconducting behavior has been observed in the Sr2RuO4-Sr3Ru2O7 eutectic system as grown by the flux-feeding floating zone technique. A supercurrent flows across a single interface between Sr2RuO4 and Sr3Ru2O7 areas at distances that are far beyond those expected in a conventional proximity scenario. The current-voltage characteristics within the Sr3Ru2O7 macrodomain, as extracted from the eutectic, exhibit signatures of superconductivity in the bilayered ruthenate. Detailed microstructural, morphological and compositional analyses address issues on the concentration and the size of Sr2RuO4 inclusions within the Sr3Ru2O7 matrix. We speculate on the possibility of inhomogeneous superconductivity in the eutectic Sr3Ru2O7 and exotic pairing induced by the Sr2RuO4 inclusions.Comment: Pages 4, figures 3, submitted to Phys. Rev. Let

    Modeling of shock absorption in athletics track surfaces

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    In this work, the possibility of predicting the force reduction (FR) characterizing the shock absorption capability of track surfaces by finite element modeling was investigated. The mechanical responses of a typical sport surface and of a reference material were characterized by quasi-static uniaxial compression experiments and fitted by Neo-Hookean and Mooney–Rivlin’s hyperelastic models to select the more appropriate one. Furthermore, in order to examine the materials behavior at strain rates typical of athletics applications, the rate dependence of the constitutive parameters was investigated. A finite element model, taking into consideration the post-impact nonlinear dynamics of the track surface and of the system (track surface + artificial athlete), was developed and validated through comparison with the results of FR tests. The simulations showed a very good agreement with the experiments and allowed to interpret the experimentally observed combined effect of track thickness and material intrinsic properties on the overall surface behavior

    The Mature Adults Cohort of the Malawi Longitudinal Study of Families and Health (MLSFH-MAC)

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    Cohort purpose: The Mature Adults Cohort of the Malawi Longitudinal Study of Families and Health (MLSFH-MAC) contributes to global aging studies by providing a rare opportunity to study the processes of individual and population aging, the public health and social challenges associated with aging and the coincident shifts in disease burdens, in a low-income, high HIV prevalence, sub-Saharan African (SSA) context. Design and Measures: The MLSFH-MAC is a population-based cohort study of mature adults aged 45 years and older living in rural communities in three districts in Malawi (Mchinji, Balaka and Rumphi). Initial enrollment at baseline is 1,266 individuals in 2012. MLSFH-MAC follow-ups were in 2013, 2017, and 2018. Survey instruments cover aging-related topics such as cognitive and mental health, NCDs and related health literacy, subjective survival expectations, measured biomarkers including HIV, grip strength, hypertension, fasting glucose, BMI, a broad range of individual- and household-level social and economic information, a 2018 qualitative survey of mature adults and community officials, 2019 surveys of village heads, health care facilities and health care providers in the MLSFH-MAC study areas. Unique features: MLSFH-MAC is a data resource that covers 20 years of the life course of cohort members and provides a wealth of information unprecedented for aging studies in a low-income SSA context that broadly represents the socioeconomic environment of millions of individuals in south-eastern Africa. Among these are the longitudinal population-based data on depression and anxiety using clinically-validated instruments. MLSFH-MAC is also vanguard in measuring longitudinal changes in cognitive health among older individuals in SSA. Complemented by contextual and qualitative information, the extensive MLSFH-MAC data facilitate a life-course perspective on aging that reflects the dynamic and distinct settings in which people reach older ages in SSA LICs. Across many domains, MLSFH-MAC also allows for comparative research with global aging studies through harmonized measures and instruments. Collaboration and data access: Public-use version of the 2012 (baseline) MLSFH-MAC data can be requested at http://www.malawi.pop.upenn.edu. Sharing of additional MLSFH-MAC data is currently possible as part of collaborative research projects (if not overlapping with ongoing research projects, and subject to a Data Use Agreement)

    Periodontal disease in a patient receiving Bevacizumab: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Bevacizumab is a monoclonal antibody that inhibits the action of vascular endothelial growth factor (VEGF) thereby acting as an angiogenesis inhibitor. As a result, supply of oxygen and nutrients to tissues is impaired and tumour cell growth is reduced. Reported side effects due to bevacizumab are hypertension and increased risk of bleeding. Bowel perforation has also been reported. Periodontal disease in patients on bevacizumab therapy has not been reported before.</p> <p>Case Presentation</p> <p>We report a case of a forty-three year old woman who developed periodontitis whilst receiving bevacizumab for lung cancer. The periodontal disease remained stable on discontinuation of the drug.</p> <p>Conclusion</p> <p>Further investigations are needed to determine the mechanism for bevacizumab-induced periodontal disease.</p

    Effectiveness of an Interprofessional Education Event for Graduate Health Professional Students

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    ABSTRACT Purpose: The purpose of this study was to investigate the impact of a single, optional, half-day, interprofessional education (IPE) event for a myriad of graduate-level health professional students (n=44) at a university in Illinois, USA. Methods: The researchers in this study examined students’ performance on two out of six of the domains on the Interprofessiomnal Collaborator Assessment Rubric (ICAR): Roles and Responsibilities and Communication Strategies. This study also investigated quantitative and qualitative findings related to student perceptions regarding this IPE opportunity. Results: Results indicated that students met or exceeded the minimum competency for the ranking of “developing” for all 6 of the behaviors evaluated. Results also revealed that this half-day extracurricuricular IPE event was viewed favorably by health-professional students and created a venue whereby students belonging to different health professional programs can enter into discussions and learn about each others’ respective roles and responsibilities in patient care. Conclusion: The creation and implementation of short term extracurricular IPE events may be a valuable alternative for healthcare programs that are unable to implement IPE activities due to some of the common barriers impacting the development, implementation, or continuation of IPE opportunities
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