130,918 research outputs found
Meso-scale response of concrete under high temperature based on coupled thermo-mechanical and pore-pressure interface modeling
No full textThis work proposes a meso-scale approach for modeling the failure behavior of concrete exposed at elevated temperature inducing thermal damage. The procedure accounts for a thermo-mechanical and pore-pressure based interface constitutive rule. More specifically, the model represents a straightforward extension of a coupled thermo-mechanical fracture energy-based interface formulation, accounting now for damage induced by the temperature dependent pore-pressure effects in concrete. The nonlinear response of the proposed fully coupled interface model for porous cohesive-frictional composites, like concrete, is activated under kinematic, temperature and/or hydraulic increments (with or without jumps). A simplified procedure is proposed to consider the temperature dependent pore-pressure action. After describing the updated version of the interface model, this work focuses on numerical analyses of concrete failure response under high temperature tests. Particularly, meso-scale analyses demonstrate the predictive capabilities of the proposed formulation.Fil: Caggiano, Antonio. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Centro de Métodos Numéricos y Computacionales en Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Schicchi, Diego Said. Universitat Bremen; AlemaniaFil: Etse, Jose Guillermo. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Centro de Métodos Numéricos y Computacionales en Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Ripani, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Construcciones y Estructuras. Laboratorio de Materiales y Estructuras; Argentin
Aspetti ultrastutturali al microscopio a scansione dell' epitelio corneale del coniglio.
No full textGli A.A. hanno studiato l' aspetto morfologico al M.E.S della superficie dell' epitelio corneale di conigli
A Case of Primary Localized Small Bowel Amyloidosis Studied by 18F-Choline and Contrast-Enhanced 18F-FDG PET/CT
No full textAmyloidosis is a rare hereditary or acquired protein deposition disorder with different etiologies, characterized by pathological protein deposition essentially in nearly any organs or tissues. There are 2 major forms: primary and secondary amyloidosis. Moreover, it is possible to have systemic or localized disease. The localized form of amyloidosis affecting the small intestine is rare, and it is characterized by the formation of precursor proteins at the site of the lesion. We report a case of localized small bowel amyloidosis studied by F-choline and F-FDG-iodinated PET/CT performed for staging an aggressive prostatic cancer
Strength and durability of concrete subjected to high temperature: Continuous and discrete constitutive approaches
No full textThe action of high temperature in concrete is a field of much interest and attention due to its strong influence in strength, durability and serviceability conditions. Long-term exposures to high temperature fields strongly affect the most relevant mechanical properties of concrete materials such as cohesion, friction, stiffness and strength. In this work, two alternatives approaches for the analysis of failure behavior of concrete subjected to high temperatures are discussed and their predictions analyzed. Specifically, a thermodynamic gradient poroplastic model based on the continuous or smeared-crack approach and an interface model based on the discrete crack approach are developed. After describing the main aspects of both models, this work focuses on the analysis of their results in terms of the degradation of concrete durability and strength capacities when subjected to severe thermal fields. The results demonstrate the comparative advantages of the discrete approach to analyze at both the macroscopic and mesoscopic scale the complex degradation processes of concrete constituents at high temperature, thanks to the robustness, stability and overall simplicity of the discrete model approach. Furthermore, the results show the capabilities of the continuous model to analyze the durability degradation of concrete at material level
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
DISCONTINUOS APPROACH FOR MESO-SCALE MODELING OF POROUS MATERIALS LIKE CONCRETE UNDER HIGH TEMPERATURE
No full textMeasurement of the2H(d, ?)4He reaction at intermediate excitation energies
No full textThe2H(d, gamma)4He differential cross section was measured at deuteron laboratory energies of 20, 24, and 28 MeV between thetacm=45° and thetacm=135°. AtE d =28 MeV a complete angular distribution was determined and fitted with Legendre polynomials. The ratioR=dsgr/dOHgr (thetacm=90°)/dsgr/dOHgr (thetacm=135°) was measured for each deuteron energy
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