Resolved maps of stellar mass and SED of galaxies from optical/NIR imaging and SPS models

We report on the method developed by Zibetti, Charlot and Rix (2009) to construct resolved stellar mass maps of galaxies from optical and NIR imaging. Accurate pixel-by-pixel colour information (specifically g-i and i-H) is converted into stellar mass-to-light ratios with typical accuracy of 30%, based on median likelihoods derived from a Monte Carlo library of 50,000 stellar population synthesis models that include dust and updated TP-AGB phase prescriptions. Hence, surface mass densities are computed. In a pilot study, we analyze 9 galaxies spanning a broad range of morphologies. Among the main results, we find that: i) galaxies appear much smoother in stellar mass maps than at any optical or NIR wavelength; ii) total stellar mass estimates based on unresolved photometry are biased low with respect to the integral of resolved stellar mass maps, by up to 40%, due to dust obscured regions being under-represented in global colours; iii) within a galaxy, on local scales colours correlate with surface stellar mass density; iv) the slope and tightness of this correlation reflect/depend on the morphology of the galaxy.Comment: 4 pages, 2 figures, to appear in the proceedings of the IAU Symposium 262 "Stellar Populations: Planning for the Next Decade", Charlot & Bruzual ed

Should home-based HIV testing and counseling services be offered periodically in programs of ARV treatment as prevention? A case study in Likoma (Malawi).

To reduce HIV incidence, prevention programs centered on the use of antiretrovirals require scaling-up HIV testing and counseling (HTC). Home-based HTC services (HBHTC) increase HTC coverage, but HBHTC has only been evaluated during one-off campaigns. Two years after an initial HBHTC campaign ("round 1"), we conducted another HBHTC campaign ("round 2") in Likoma (Malawi). HBHTC participation increased during round 2 among women (from 74 to 83%, P < 0.01). New HBHTC clients were recruited, especially at ages 25 and older. Only 6.9% of women but 15.9% of men remained unreached by HBHTC after round 2. HIV prevalence during round 2 was low among clients who were HIV-negative during round 1 (0.7%), but high among women who received their first ever HIV test during round 2 (42.8%). The costs per newly diagnosed infection increased significantly during round 2. Periodically conducting HBHTC campaigns can further increase HTC, but supplementary interventions to enroll individuals not reached by HBHTC are needed

In Situ Experiment and Modelling of RC-Structure using Ambient vibration and Timoshenko Beam

International audienceRecently, several experiments were reported using ambient vibration surveys in buildings to estimate the modal parameters of buildings. Their modal properties are full of relevant information concerning its dynamic behaviour in its elastic domain. The main scope of this paper is to determine relevant, though simple, beam modelling whose validity could be easily checked with experimental data. In this study, we recorded ambient vibrations in 3 buildings in Grenoble selected because of their vertical structural homogeneity. First, a set of recordings was done using a 18 channels digital acquisition system (CityShark) connected to six 3C Lennartz 5s sensors. We used the Frequency Domain Decomposition (FDD) technique to extract the modal parameters of these buildings. Second, it is shown in the following that the experimental quasi-elastic behaviour of such structure can be reduced to the behaviour of a vertical continuous Timoshenko beam. A parametric study of this beam shows that a bijective relation exists between the beam parameters and its eigenfrequencies distribution. Consequently, the Timoshenko beam parameters can be estimated from the experimental sequence of eigenfrequencies. Having the beam parameters calibrated by the in situ data, the reliability of the modelling is checked by complementary comparisons. For this purpose, the mode shapes and eigenfrequencies of higher modes are calculated and compared to the experimental data. A good agreement is also obtained. In addition, the beam model integrates in a very synthetic way the essential parameters of the dynamic behaviour

Atypical dynamics of materials with periodic microstructure and local resonance

This work investigates the dynamic behavior of periodic unbraced frame structures made up of interconnected beams. Two types of microstructures are especially studied: non-orthogonal unbraced frame and honeycombs. The microstructure being much stiffer in compression than in shear, a great variety of behaviors can occur. Assuming the condition of scale separation is respected, the dynamical behaviors at the leading order are approached by the homogenisation method of periodic discrete media. In the studied ranges, the local elements behave ever in quasi-statics, ever in dynamics. For studied materials, the elastic laws are given in function of the elements properties. These laws correspond to upgraded materials as double gradient media or meta-material. To illustrate their atypical properties, propagations of 'shear' and 'compression' waves are studied. In the presence of the local resonance, the form of the equations is unchanged but the mass depends on the frequency and, as a result, frequency bandgaps appear

Dynamic numerical simulations of dry-stone retaining walls: identification of the seismic behaviour factor

Dry-stone retaining walls can be found worldwide and constitute critical assets of the built heritage for many sloped territories, holding cultural and economic value. Their design currently follows empirical rules, though the first steps towards a static safety assessment have recently been proposed in the scientific and engineering literature. However, the seismic design of these structures still lacks research studies. Therefore, this work conducts discrete element simulations to assess their dynamic behaviour. First, the approach is validated through existing scaled-down shaking table experiments, and it is found that the numerical simulations are conservative (i.e., on the safe side). Next, full-scale dry-stone retaining walls are subjected to harmonic excitations as an idealisation of earthquakes. Finally, based on a simplified limit-equilibrium analytical tool, their seismic behaviour factor is estimated for the first time in the literature, which falls within the proposed values of the European standards (Eurocode 8). This will allow engineers to adopt a validated behaviour factor in practice to assess and design dry-stone retaining walls with a pseudo-static approach.This research was funded by the French Ministry of Education and Research, through the PhD grant attributed to the first author. This work was partly financed by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020

Large temporal variations of functional properties of outdoor equestrian arena surfaces and a new concept of evaluating reactivity with light weight deflectometer settlement curves

Sports physiological properties of ten sand or sand-mineral outdoor arenas, five with vertical drainage systems and five with an ebb and flow like system were assessed over a period of eight weeks. For each arena, the riding zone was spatially delineated, nine locations at medium to intensely used zones were selected by simple random sampling and used along the whole measurement period. A total of 72 values for the dynamic deflection modulus (Evd), attenuation (s/v), settlement (s) and moisture content (Vol %) were analyzed for each arena. A novel technique to analyze the settlement curves of the light weight deflectometer (LWD) to describe reactivity of the footing surface was introduced. Statistical testing was done by linear mixed models. Three of the five arenas with a vertical watering system were judged to be hard (Evd > 20 MN/m2), whereas all five arenas with an ebb and flow like watering systems were medium hard (Evd = 10-20 MN/m2) over the entire eight weeks. Significant (p<0.01) temporal differences in Evd, s/v and moisture were demonstrated for both watering systems; however, the spatial and temporal variations were much lower with the ebb-flow system. Temporal consistency in the parameters over the test weeks appeared to be a criterion for stability of the arena surface. The analysis of the settlement curves of the LWD showed that the slope symmetry has a large potential to describe the restoration of the energy of an equestrian surface than only the settlement, which requires further validation

Synthesis of fused tricyclic systems by thermal cope rearrangement of furan-substituted vinyl cyclopropanes

A novel method for the stereoselective construction of hexahydroazuleno[4,5-b]furans from simple precursors has been developed. The route involves the use of our recently developed Brønsted acid catalysed cyclisation reaction of acyclic ynenones to prepare fused 1-furanyl-2-alkenylcyclopropanes that undergo highly stereoselective thermal Cope rearrangement to produce fused tricyclic products. Substrates possessing an E-alkene undergo smooth Cope rearrangement at 40 °C, whereas the corresponding Z-isomers do not react at this temperature. Computational studies have been performed to explain the difference in behaviour of the E- and Z-isomers in the Cope rearrangement reaction. The hexahydroazuleno[4,5-b]furans produced by Cope rearrangement have potential as advanced intermediates for the synthesis of members of the guaianolide family of natural products

The Social and the Sexual: Networks in Contemporary Demographic Research

The analysis of networks has become an important theme in contemporary demographic research in both developed and developing countries, including investigations of the determinants of fertility behaviors, the interaction between social network and social structures and population policies, the role of intergenerational networks in aging societies, and the relevance for sexual networks for the spread of HIV AIDS. This paper reviews the current research on networks across several domains in demographic research, and it discusses some of the specific challenges of network-based approaches with respect to data collection, analytic approaches and methodologies, interpretation of results, and micro-to-macro aggregation by drawing on research conducted as part of the Kenyan Diffusion and Ideational Change Project (KDICP), the Malawi Longitudinal Study of Families and Health (MLSFH) and the Likoma Network Study (LNS)

Dominant Role of CD80–CD86 Over CD40 and ICOSL in the Massive Polyclonal B Cell Activation Mediated by LATY136F CD4+ T Cells

Coordinated interactions between T and B cells are crucial for inducing physiological B cell responses. Mutant mice in which tyrosine 136 of linker for activation of T cell (LAT) is replaced by a phenylalanine (LatY136F) exhibit a strong CD4+ T cell proliferation in the absence of intended immunization. The resulting effector T cells produce high amounts of TH2 cytokines and are extremely efficient at inducing polyclonal B cell activation. As a consequence, these LatY136F mutant mice showed massive germinal center formations and hypergammaglobulinemia. Here, we analyzed the involvement of different costimulators and their ligands in such T–B interactions both in vitro and in vivo, using blocking antibodies, knockout mice, and adoptive transfer experiments. Surprisingly, we showed in vitro that although B cell activation required contact with T cells, CD40, and inducible T cell costimulator molecule-ligand (ICOSL) signaling were not necessary for this process. These observations were further confirmed in vivo, where none of these molecules were required for the unfolding of the LAT CD4+ T cell expansion and the subsequent polyclonal B cell activation, although, the absence of CD40 led to a reduction of the follicular B cell response. These results indicate that the crucial functions played by CD40 and ICOSL in germinal center formation and isotype switching in physiological humoral responses are partly overcome in LatY136F mice. By comparison, the absence of CD80–CD86 was found to almost completely block the in vitro B cell activation mediated by LatY136F CD4+ T cells. The role of CD80–CD86 in T–B cooperation in vivo remained elusive due to the upstream implication of these costimulatory molecules in the expansion of LatY136F CD4+ T cells. Together, our data suggest that CD80 and CD86 costimulators play a key role in the polyclonal B cell activation mediated by LatY136F CD4+ T cells even though additional costimulatory molecules or cytokines are likely to be required in this process

Genome sequences of equine herpesvirus 1 strains from a European outbreak of neurological disorders linked to a horse gathering in Valencia, Spain, in 2021

Five equine herpesvirus 1 (EHV-1) genome sequences with links to an EHV-1 outbreak with neurological disorders after a horse gathering in Valencia, Spain, in February 2021, were determined. All strains showed the closest relationships to strains from Belgium and the United Kingdom, indicating a common source of infection