The Hvar survey for roAp stars: II. Final results (Research Note)

The 60 known rapidly oscillating Ap (roAp) stars are excellent laboratories to test pulsation models in the presence of stellar magnetic fields. Our survey is dedicated to search for new group members in the Northern Hemisphere. We attempt to increase the number of known chemically peculiar stars that are known to be pulsationally unstable. About 40 h of new CCD photometric data of 21 roAp candidates, observed at the 1m Austrian-Croatian Telescope (Hvar Observatory) are presented. We carefully analysed these to search for pulsations in the frequency range of up to 10mHz. No new roAp star was detected among the observed targets. The distribution of the upper limits for roAp-like variations is similar to that of previoius similar efforts using photomultipliers and comparable telescope sizes. In addition to photometric observations, we need to consolidate spectroscopic information to select suitable targets.Comment: 8 pages, 5 figures, accepted by Astronomy & Astrophysic

Putting the gender back in digital housekeeping

Prior work examining technology usage and maintenance practices in homes describes division of labor in terms of technical expertise. In this paper, we offer a counter-narrative to this explanation for engagement with Ubiquitous Computing. Using feminist theory as an analytic lens, we examine how gender identity work is a determining factor of whether and how people engage with digital technologies in their homes. We present a model of gender & technical identity co-construction

Ablation of solids by femtosecond lasers: ablation mechanism and ablation thresholds for metals and dielectrics

The mechanism of ablation of solids by intense femtosecond laser pulses is described in an explicit analytical form. It is shown that at high intensities when the ionization of the target material is complete before the end of the pulse, the ablation mechanism is the same for both metals and dielectrics. The physics of this new ablation regime involves ion acceleration in the electrostatic field caused by charge separation created by energetic electrons escaping from the target. The formulae for ablation thresholds and ablation rates for metals and dielectrics, combining the laser and target parameters, are derived and compared to experimental data. The calculated dependence of the ablation thresholds on the pulse duration is in agreement with the experimental data in a femtosecond range, and it is linked to the dependence for nanosecond pulses.Comment: 27 pages incl.3 figs; presented at CLEO-Europe'2000 11-15 Sept.2000; papers QMD6 and CTuK11

Unconventional magnetism in all-carbon nanofoam

We report production of nanostructured carbon foam by a high-repetition-rate, high-power laser ablation of glassy carbon in Ar atmosphere. A combination of characterization techniques revealed that the system contains both sp2 and sp3 bonded carbon atoms. The material is a novel form of carbon in which graphite-like sheets fill space at very low density due to strong hyperbolic curvature, as proposed for ?schwarzite?. The foam exhibits ferromagnetic-like behaviour up to 90 K, with a narrow hysteresis curve and a high saturation magnetization. Such magnetic properties are very unusual for a carbon allotrope. Detailed analysis excludes impurities as the origin of the magnetic signal. We postulate that localized unpaired spins occur because of topological and bonding defects associated with the sheet curvature, and that these spins are stabilized due to the steric protection offered by the convoluted sheets.Comment: 14 pages, including 2 tables and 7 figs. Submitted to Phys Rev B 10 September 200

Gender and the Lived Body Experience of Academic Work during Covid19

The rapid transition to online teaching in response to Covid-19 presented unprecedented challenges for academic communities. Staff had vastly different experiences of engaging with technology, and these experiences are shaped by factors including gender, (dis)ability, socio-economic resources and caring responsibilities. We report findings from an intersectional interview examination of how 412 staff in a large London-based university adapted to teaching and researching from home at the beginning of lockdown during the COVID-19 pandemic. In this article, we construct grounded theory around the divisibility of the body, and the conflicts arising from the need to span home and work-life, our findings illustrate how patterns of inequity for women academics converge to construct ways of managing the boundary work of home and work with different degrees of successes. We document how management support and/ or existing expertise were vital to enable women academics to overcome obstacles to equitable work.