MeerLICHT phot. of hot sub-luminous stars

A full list of 610 sdB candidates, similar to Table A.1 of the paper. Note that, here, the first column is different from the first column of Table A.1. (1 data file)

Identifying and characterising the population of hot sub-luminous stars with multi-colour MeerLICHT data

Context. Colour–magnitude diagrams reveal a population of blue (hot) sub-luminous objects with respect to the main sequence. These hot sub-luminous stars are the result of evolutionary processes that require stars to expel their obscuring, hydrogen-rich envelopes to reveal the hot helium core. As such, these objects offer a direct window into the hearts of stars that are otherwise inaccessible to direct observation. Aims. MeerLICHT is a wide-field optical telescope that collects multi-band photometric data in six band filters (u, g, r, i, z, and q), whose primary goals are to study transient phenomena, gravitational wave counterparts, and variable stars. We showcase MeerLICHT’s capabilities of detecting faint hot subdwarfs and identifying the dominant frequency in the photometric variability of these compact hot stars, in comparison to their Gaia DR3 data. We hunt for oscillations, which will be an essential ingredient for accurately probing stellar interiors in future asteroseismology. Methods. Comparative MeerLICHT and Gaia colour–magnitude diagrams are presented as a way to select hot subdwarfs from our sample. A dedicated frequency determination technique is developed and applied to the selected candidates to determine their dominant variability using time-series data from MeerLICHT and Gaia DR3. We explore the power of both datasets in determining the dominant frequency. Results. Using the g − i colour, MeerLICHT offers a colour–magnitude diagram that is comparable in quality to that of Gaia DR3. The former, however, is more sensitive to fainter objects. The MeerLICHT colour–colour diagrams allow for the study of different stellar populations. The frequency analysis of MeerLICHT and Gaia DR3 data demonstrates the superiority of our MeerLICHT multi-colour photometry in estimating the dominant frequency compared to the sparse Gaia DR3 data. Conclusions. MeerLICHT’s multi-band photometry leads to the discovery of high-frequency faint subdwarfs. Continued observations tuned to asteroseismology will allow for mode identification using the method of amplitude ratios. Our MeerLICHT results are a proof-of-concept of the capacity of the BlackGEM instrument currently in the commissioning stage at ESO’s La Silla Observatory in Chile

Provider-initiated HIV testing and counselling for TB in low HIV prevalence settings: is it worthwhile?

We assessed the HIV-positive yield of offering provider-initiated HIV testing and counselling (PITC) for TB and the costs, in Madagascar, which has a low HIV prevalence and a high TB burden

Tensile basic creep versus compressive basic creep at early ages: comparison between normal strength concrete and a very high strength fibre reinforced concrete

The paper presents experimental results concerning the comparison of tensile and compressive basic creep behaviours at early ages of two different concretes: a normal strength concrete (NSC) and a very high strength fibre reinforced concrete (HPFRC). This research project has been done in the context of a bilateral collaboration between Polytechnique Montreal and IFSTTAR. Observations on the HPFRC showed specific compressive creep similar to the specific tensile creep. Moreover, the specific creep curves obtained under compressive and tensile loading had always positive values, i.e. they were in same direction of the applied load on specimens. Measurements made on the NSC revealed specific compressive creep with positive values (in the loading direction). However, specific tensile creep presented negative values (opposite direction of loading) for a long period. A physical explanation based on the existence of two mechanisms with opposite effect is proposed to describe these basic creep results. The first mechanism is a coupling between the microcracking process and the water transfers that lead to additional self-drying shrinkage; the second mechanism is the self-healing of concrete induced by the microcracking

Mechanical Properties

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