1,721,263 research outputs found
On the design of viscous dampers to be inserted in high-rise Moment-resisting frame structures
No full textThe object of this paper is to investigate the applicability of simplified methods for the design of viscous dampers to be inserted in high-rise moment-resisting frame structures. The simplified methods of analysis allow to easily estimate the response of an elastic structure with fluid viscous dampers by performing a modal analysis and estimating an additional damping ratio for each vibration mode of the structure. The corresponding design formulas provide a simple and fast tool for determining the damper properties corresponding to the desired values of supplemental damping ratio. Traditionally, simplified analysis formulas are derived neglecting the vertical relative displacement between the ends of the damper, but this could lead in general to overestimate the damper energy dissipation and to underestimate the required damping coefficients. This effect could become significant for medium-rise to high-rise frame structures, where the vertical relative displacement between the ends of the dampers could be comparable with the horizontal one. Therefore, modified design formulas have been proposed in literature to account for the vertical displacement of the frame nodes. The aim of this study was then to investigate the above-mentioned effect on the effectiveness of viscous dampers and to evaluate the accuracy of simplified design formulas in different conditions. In particular, a widespread simplified design method was considered together with its extension for considering the vertical displacement of the frame nodes. Thus, two distinct design criteria were identified which were examined by comparing the effects of their application both in terms of design outcomes and in terms of seismic response. An extensive numerical analysis was carried out to evaluate the accuracy of these criteria for two steel moment-resisting frames, one medium-rise and the other high-rise, equipped with damping systems designed assuming four different values of the added damping ratio and two different distributions of damper properties along the height. The analyses were performed by applying a set of seven spectrum-compatible ground motions. The response of the models with dampers was compared with the target response of a corresponding ideal structure in which the damping system was modelled with Rayleigh damping
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Role of aquaporins in the cell signalling mediated by hydrogen peroxide in leukemic cells
Full text linkRole of aquaporins in the cell signalling mediated by hydrogen peroxide in leukemic cells
F. Vieceli Dalla Sega, C. Prata, C. Caliceti, L. Zambonin, D. Fiorentini, G. Hakim, L. Landi
Department of Biochemistry “G. Moruzzi”, University of Bologna, Bologna, Italy
Aquaporins (AQP) constitute a large family of integral membrane proteins, present in all domains of life, that form pores appearing to be designed for the selective passage of water and glycerol [1]. Hydrogen peroxide has been long thought to be freely diffusible but recent evidence suggest that specific mammalian aquaporin homologues (AQP8) possess the capacity to channel H2O2 across membranes [2,3]. Moreover, it has been recently shown that human cells AQP3 expression can modulate the intracellular level of H2O2 and is required for NOX-derived H2O2 signalling [3]. Redox deregulation of proliferative pathways involving ROS (particularly H2O2) in cancer initiation and progression is now firmly established. Here we tested the hypothesis that specific isoforms of aquaporins regulate the level of intracellular H2O2 produced by NOX affecting downstream pathways linked to cell proliferation. In the present study, we show that in different leukemic cell lines NOX2 and/or NOX4 are expressed and are necessary to produce ROS that, in turn, are able to sustain glucose uptake and cell proliferation. Furthermore, we report that inhibition of aquaporins diminishes intracellular ROS accumulation either when H2O2 is produced by Nox enzymes or when is added exogenously to the medium. Finally, we observe a decrease in glucose transport following aquaporins inhibition. Taken together data suggest that aquaporins can regulate hydrogen peroxide uptake and downstream pathways mediated by H2O2
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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