Optimization of force-limiting seismic devices connecting structural subsystems

This paper is focused on the optimum design of an original force-limiting floor anchorage system for the seismic protection of reinforced concrete (RC) dual wall-frame buildings. This protection strategy is based on the interposition of elasto-plastic links between two structural subsystems, namely the lateral force resisting system (LFRS) and the gravity load resisting system (GLRS). The most efficient configuration accounting for the optimal position and mechanical characteristics of the nonlinear devices is obtained numerically by means of a modified constrained differential evolution algorithm. A 12-storey prototype RC dual wall-frame building is considered to demonstrate the effectiveness of the seismic protection strategy

F-VIPGI: a new adapted version of VIPGI for FORS2 spectroscopy. Application to a sample of 16 X-ray selected galaxy clusters at 0.6 < z < 1.2

The goal of this paper is twofold. Firstly, we present F-VIPGI, a new version of the VIMOS Interactive Pipeline and Graphical Interface (VIPGI) adapted to handle FORS2 spectroscopic data. Secondly, we investigate the spectro-photometric properties of a sample of galaxies residing in distant X-ray selected galaxy clusters, the optical spectra of which were reduced with this new pipeline. We provide basic technical information about the innovations of the new software and, as a demonstration of the capabilities of the new pipeline, we show results obtained for 16 distant (0.65 < z < 1.25) X-ray luminous galaxy clusters selected within the XMM-Newton Distant Cluster Project. We performed a spectral indices analysis of the extracted optical spectra of their members, based on which we created a library of composite high signal-to-noise ratio spectra representative of passive and star-forming galaxies residing in distant galaxy clusters. The spectroscopic templates are provided to the community in electronic form. By comparing the spectro-photometric properties of our templates with the local and distant galaxy population residing in different environments, we find that passive galaxies in clusters appear to be well evolved already at z = 0.8 and even more so than the field galaxies at similar redshift. Even though these findings would point toward a significant acceleration of galaxy evolution in densest environments, we cannot exclude the importance of the mass as the main evolutionary driving element either. The latter effect may indeed be justified by the similarity of our composite passive spectrum with the luminous red galaxies template at intermediate redshift.Comment: 15 pages, 15 figures, in press on Astronomy and Astrophysic

1.65 micron H-band Surface Photometry of Galaxies. X: Structural and Dynamical Properties of Elliptical Galaxies

We analyse the structural and dynamical properties of a sample of 324 nearby elliptical and dwarf elliptical galaxies observed during an extensive NIR survey in H-band (1.65 micron). The Fundamental Plane (FP) is determined and a significant tilt is assessed. The origins of such a tilt are investigated by means of a spherically symmetric, isotropic pressure supported dynamical model relying on the observed surface brightness profiles. The systematic variation of the shape coefficient converting the measured central velocity dispersion $sigma_0$ into the virial rms velocity $sigma_{rms}$ is found to be the main cause of the tilt, due to aperture effects. Moreover the ratio between the dynamical mass $M_{dyn}$ and the total H-band luminosity $L_H$ turns out to be roughly constant along the luminosity sequence of ellipticals: H-band luminosity is therefore a reliable and cheap estimator of the dynamical mass of the Es.Comment: 28 pages, 6 figures, accepted for publication on Ap

VIMOS Ultra-Deep Survey (VUDS): Witnessing the assembly of a massive cluster at z ~ 3.3

International audienceUsing new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z> 2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z = 3.29. This protocluster is characterized by both the large overdensity of spectroscopically confirmed members, δgal = 10.5 ± 2.8, and a significant overdensity in photometric redshift members. The halo mass of this protocluster is estimated by a variety of methods to be ~3 × 1014ℳ⊙ at z ~ 3.3, which, evolved to z = 0 results in a halo mass rivaling or exceeding that of the Coma cluster. The properties of 19 spectroscopically confirmed member galaxies are compared with a large sample of VUDS/VVDS galaxies in lower density field environments at similar redshifts. We find tentative evidence for an excess of redder, brighter, and more massive galaxies within the confines of the protocluster relative to the field population, which suggests that we may be observing the beginning ofenvironmentally induced quenching. The properties of these galaxies are investigated, including a discussion of the brightest protocluster galaxy, which appears to be undergoing vigorous coeval nuclear and starburst activity. The remaining member galaxies appear to have characteristics that are largely similar to the field population. Though we find weaker evidence of the suppression of the median star formation rates among and differences in the stacked spectra of member galaxies with respect to the field, we defer any conclusions about these trends to future work with the ensemble of protostructures that are found in the full VUDS sample

Early-type galaxies at z = 1.3. I. The Lynx supercluster: cluster and groups at z=1.3. Morphology and color-magnitude relation

We confirm the detection of 3 groups in the Lynx supercluster, at z~1.3, and give their redshifts and masses. We study the properties of the group galaxies as compared to the central clusters, RXJ0849+4452 and RXJ0848+4453, selecting 89 galaxies in the clusters and 74 galaxies in the groups. We morphologically classify galaxies by visual inspection, noting that our early-type galaxy (ETG) sample would have been contaminated at the 30% -40% level by simple automated classification methods (e.g. based on Sersic index). In luminosity selected samples, both clusters and groups show high fractions of Sa galaxies. The ETG fractions never rise above ~50% in the clusters, which is low compared to the fractions observed in clusters at z~1. However, ETG plus Sa fractions are similar to those observed for ETGs in clusters at z~1. Bulge-dominated galaxies visually classified as Sas might also be ETGs with tidal features or merger remnants. They are mainly red and passive, and span a large range in luminosity. Their star formation seems to have been quenched before experiencing a morphological transformation. Because their fraction is smaller at lower redshifts, they might be the spiral population that evolves into ETGs. For mass-selected samples, the ETG fraction show no significant evolution with respect to local clusters, suggesting that morphological transformations occur at lower masses and densities. The ETG mass-size relation shows evolution towards smaller sizes at higher redshift in both clusters and groups, while the late-type mass-size relation matches that observed locally. The group ETG red sequence shows lower zero points and larger scatters than in clusters, both expected to be an indication of a younger galaxy population. The estimated age difference is small when compared to the difference in age at different galaxy masses.Comment: ApJ, submitted - referee report answered - iterating with the refere

A Fit to the Available <i>e</i>⁺<i>e</i>⁻ → <inline-formula><math display="inline"><semantics><mrow><msubsup><mi mathvariant="sans-serif">Λ</mi><mi>c</mi><mo>+</mo></msubsup><msubsup><mover accent="true"><mi mathvariant="sans-serif">Λ</mi><mo>¯</mo></mover><mi>c</mi><mo>−</mo></msubsup></mrow></semantics></math></inline-formula> Cross Section Data Nearby Production Threshold by Means of a Strong Correction to the Coulomb Enhancement Factor

There are two available sets of data on the e+e−→Λc+Λ¯c− cross section at energies close to the production threshold, collected by the Belle and by the BESIII Collaborations. The measurement of the former, performed by means of the initial state radiation technique, is compatible with the presence of a resonance, called ψ(4660), observed also in other final states. On the contrary, the latter is measured an almost flat and hence non-resonant cross section in the energy region just above the production threshold, but the data stop before the possible rise in the cross section for the resonant production. We propose an effective model to describe the behavior of the data near this threshold, which is based on a Coulomb-like enhancement factor due to the strong interaction among the final state particles. In the framework of this model, it is possible to describe both datasets