492 research outputs found

    A quasi-static nonlinear analysis for assessing the fire resistance of 3d frames exploiting time-dependent yield surface

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    In this work an automatic procedure for evaluating the axial force-biaxial bending yield surface of reinforced concrete sections in fire is proposed. It provides an accurate time-dependent expression of the yield condition by a section analysis carried out once and for all, accounting for the strength reduction of the materials, which is a function of the fire duration. The equilibrium state of 3D frames with such yield conditions, once discretized using beam finite elements, is formulated as a nonlinear vectorial equation defining a curve in the hyperspace of the discrete variables and the fire duration. A generalized path-following strategy is proposed for tracing this curve and evaluating, if it exists, the limit fire duration, that is the time of exposure which leads to structural collapse. Compared to the previous proposals on the topic, which are limited to local sectional checks, this work is the first to present a global analysis for assessing the fire resistance of 3D frames, providing a time history of the fire event and taking account of the stress redistribution. Numerical examples are given to illustrate and validate the proposal

    Picturebooks and gender : making informed choices for equitable early childhood classrooms.

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    We examine picturebooks through a feminist lens, understanding that children’s literature and media can limit and expand how young children access gender representations. We describe four categories that increase teacher knowledge to select books with multiple and varied gender representations for children in their classrooms. These four categories are gender binaries, discourses of childhood innocence, intersectionality, and heteronormativity. We illustrate each category with two quality books that maintain and disrupt each theme. We hope teachers will find the categories useful for thoughtfully selecting books for classroom libraries, read aloud, and discussion

    Empirical vulnerability curves for Italian mansory buildings: evolution of vulnerability model from the DPM to curves as a function of accelertion

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    In the framework of the emergency management in the case of seismic events, the evaluation of the expected damage represents a basic requirement for risk informed planning. Seismic risk is defined by the probability to reach a level of damage on given exposed elements caused by seismic events occurring in a fixed period and in a fixed area. To this purpose, the expected seismic input, the exposed elements and their vulnerability have to be correctly evaluated. The aim of the research is to define a correct model of vulnerability curves, in PGA, for masonry structures in Italy, by heuristic approach starting from damage probability matrices (DPMs). To this purpose, the PLINIVS database, containing data on major Italian seismic events, has been used and supported by “critical” assumption on missing data. To support the reliability of this assumption, two vulnerability models, considering or not the hypothesis on the missing data, have been estimated and used to calculate the seismic scenario of the L’Aquila 2009 earthquake through the IRMA (Italian Risk MAp) platform. Finally, a comparison between the outcomes elaborated by IRMA platform and the observed damage collected in the AEDES forms, has been done. © 2020, The Author(s)

    Caesar II: An Italian decision support tool for the seismic risk. The case study of Torre Pellice, Villar Pellice and Pinerolo municipalities

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    Italy is a country with high seismic risk; however, a broad seismic classification of the national territory has been introduced only in the last twenty years. Therefore, most of the existing buildings stock do not comply with the current anti-seismic codes. In recent years, the seismic events that occurred in Italy have highlighted the complexity of emergency management and the great challenge for public authorities called to answer to the post-event reconstruction and the planning of effective risk prevention and mitigation measures implemented in "peacetime". In this perspective, the CAESAR II project (Controlling, Mitigating and Managing Earthquake Emergency: Cost-Benefit and Multi-criteria Analysis of Impact Scenarios for Risk Reduction and Increased Resilience) has been developed as a decision support system for public authorities engaged in the development of seismic disaster risk reduction plans. CAESAR II includes a module for the simulation of retrofitting measures applied at the municipal scale, integrating different categories of anti-seismic and energy improvement measures based on the vulnerability analysis of the existing buildings stock. The CAESAR II tool's core is the module for evaluating "seismic impact scenarios" based on the end-users' hazard. The output of the model includes information on expected damage levels for buildings (from D0-no damage to D5- total collapse) and population (dead, injured and homeless). Impact scenarios can be customised according to the minimum unit of analysis assumed (municipality or 250x250m square mesh grid) and the availability of exposure data (from national census data or survey on the spot building by building according to the PLINIVS form). Scenarios include geo-referenced data managed by geo-servers to exchange data in a format compliant with OGC (Open Gis Consortium) standards and the European INSPIRE Directive. Simulation results can be further processed through the Multi-Criteria and Cost-Benefit Analysis modules to support the comparative assessment of alternative seismic and energy measurements. In this work, the procedures included in CAESAR II are described and a case study is reported. It concerns the analysis of the expected damage assessment on buildings and population for three municipalities in northern Italy, Torre Pellice, Villar Pellice and Pinerolo (Piedmont Region)

    The role of small-scale fisheries in Mediterranean coastal communities. An analytical framework for their development.

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    Small-scale fisheries make an important contribution to nutrition, food security, sustainable livelihoods and poverty alleviation of coastal areas. This paper deals with the integration of small-scale fisheries in coastal communities, their contribution to sustainable development, and some methodological approaches that can be used to carry out this kind of analysis. Concepts as supply chain, blue growth, ecosystem services and multifunctionality are discussed and finally integrated in a framework for the analysis of coastal communities, which are assimilated to a specific pattern of industrial clusters. The approach proposed represents a useful and relatively easy to use instrument supporting the involvement of people, enterprises and institutions for the analysis of the local context and the definition of future strategies, in order to create a favourable environment offering income and employment opportunities to marginalized communities

    The finding of vascular and urinary anomalies in the harvested kidney for transplantation.

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    INTRODUCTION: In kidney transplantation, anatomical vascular and excretory anomalies may represent causes of failure. Today's surgical techniques have made the most of the organs with anatomic anomalies and iatrogenic injury successfully used for transplantation. MATERIALS AND METHODS: From January 2000 to June 2006, we harvested 230 kidneys, of including 88 kidneys (20%) with vascular, urinary, or vascular-urinary anomalies; 64 kidneys were implanted and 15 were sent to other transplantation centers. Only 9 kidneys were not appropriate for transplantation. RESULTS: All patients who received kidneys with the above-mentioned anomalies were carefully examined after the transplantation and short-term and long-term complications were evaluated with respect to controls without anomalies. DISCUSSION: Renal anatomic anomalies are frequently observed during kidney transplantation and may produce postsurgical complications. However, the presence of these anomalies does not necessarily imply the impossibility of using the kidney for a transplant, especially because of improved surgical techniques. Our experience in transplantation procedures showed that even if kidneys present the above-mentioned anomalies they can still be considered appropriate for transplantation when we perform a correct harvesting/back-table transplant surgery. So vascular and urinary anomalies have to be considered always an incentive to research new surgical solutions and to perform a careful surgical technique

    Ion rocket engine development Quarterly report no. 3, 1 Apr. - 30 Jun. 1965

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    Integral focus cesium contact ion rocket engine and iridium and rhenium coated porous tungsten ionizer evaluation

    A small organic compound enhances the religation reaction of human topoisomerase I and identifies crucial elements for the religation mechanism

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    The different steps of the human Top1 (topoisomerase I) catalytic cycle have been analysed in the presence of a pentacyclic-diquinoid synthetic compound. The experiments indicate that it efficiently inhibits the cleavage step of the enzyme reaction, fitting well into the catalytic site. Surprisingly the compound, when incubated with the binary topoisomerase–DNA cleaved complex, helps the enzyme to remove itself from the cleaved DNA and close the DNA gap, increasing the religation rate. The compound also induces the religation of the stalled enzyme–CPT (camptothecin)– DNA ternary complex. Analysis of the molecule docked over the binary complex, together with its chemical properties, suggests that the religation enhancement is due to the presence on the compound of two oxygen atoms that act as hydrogen acceptors. This property facilitates the deprotonation of the 5 DNA end, suggesting that this is the limiting step in the topoisomerase religation mechanism

    Transplantation and young surgeons in italy

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    The relation between young surgeons and transplantation has always been a "love and hate" one. Until a few years ago this branch of surgery was seen as pioneering, with extreme and and extensive training, and was reserved to few elected members. Nowadays things are different. In this article we try to understand the true reasons that young Italian surgeons avoid transplantation surgery
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