1,721,025 research outputs found
La innovación tecnologica en la universidad. Enseñanza, investigación y extensión en el habitat social. Estudio de caso
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Il commercio delle armi: trasparenza è controllo? Il registro delle armi convenzionali delle Nazioni Unite
No full textComparative study of the inelastic response of base isolated buildings
No full textThis article presents a numeric comparative study of the inelastic structural response of base isolated
buildings. The comparative study includes the following isolation systems: laminated rubber bearings,
New Zealand one, pure friction and the frictional pendulum ones. The study is based on obtaining nonlinear
response spectra for various design parameters using six earthquake records. Usually the base
isolation of a new building seeks to maintain the structure in the linear elastic range. The response of old
weak buildings or the response of new ones subjected to extreme earthquakes may not be, necessarily,
in the aforementioned ideal elastic range. Consequently, it is important to characterize the response of
isolated buildings responding inelastically. A conclusion from this research is that the isolators aect
signicantly the structural response of weak systems. Rubber isolators seem slightly less sensitive to
plastication that may occur in the structure compared to friction isolators. Ductility demands in the
structure are aected signicantly by friction and neoprene protected systems, in particular sliding ones
where larger demands are obtained
Numerical Efficiency Assessment of Energy Dissipators for Seismic Protection of Buildings
No full textThis paper presents a two-dimensional numerical study on the nonlinear seismic response of buildings equipped with two types of energy dissipators: Constant Friction Slip Braces (CFSB) and Adding Damping and Stiffness (ADAS). Three types of reinforced concrete buildings with 3, 7 and 15 storeys, representatives of the short-medium- and long-period ranges, are considered. Dissipators are placed in steel diagonal braces in all the floors. The sliding threshold (or yielding) forces for each mechanism are selected using two different criteria: (i) they are taken as 50, 75 and 100 per cent of those generated by the equivalent static lateral forces recommended by the UBC-91 for a ductile moment resisting frame and (ii) they are constant in the whole building (this constant value is chosen equal to the maximum forces obtained with the previous criterion). The input consists of ten recorded earthquakes (normalized with respect to their Housner intensity) corresponding to medium and stiff local soil conditions. Average values on the ten registers are given for the maximum horizontal displacement, the base shear, the energy dissipated and the interstorey drift. The possibility of failure in some devices has been numerically simulated to assess the robustness of the system. The obtained results show that both devices are useful to reduce the response compared to the bare frame and that CFSB is more efficient than ADAS; for 7- and 15-storey frames the lateral displacement with CFSB is even smaller than the one for the braced frame (rigid connections instead of dissipators). The conclusions are expected to provide simple design guidelines
The dual function of the MHC class II against human oncogenic retroviruses
No full textThe AIR-1 gene product CIITA is the master
regulator of MHC class II gene expression. This makes
CIITA a crucial element for triggering antigen presentation
to CD4+ T cells and thus the cascade of events leading to
an efficient adaptive immune response. Recently we
discovered that CIITA is also endowed with the capacity to
directly inhibit both HIV-1 and HTLV retroviruses in
infected cells by blocking the function of the viral
transactivators Tat and Tax. Thus CIITA exerts a dual role
against human retroviruses. The first, classical role is the
upregulation of MHC class II expression and thus the
capacity to present viral antigens to CD4+ T cells. The
other, evolutionary new and fundamental role is to inhibit
directly viral replication and spreading. We will discuss the
molecular mechanisms by which CIITA counteracts
specifically viral transactivators. These distinct properties
of CIITA will shed new light on the molecular mechanisms
of adaptive coevolution of hosts and pathogens and may be
exploited to envisage novel therapeutic strategies aimed at
counteracting retroviral infections and thus their oncogenic
potential
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
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