Quantum field theory predicts a nonlinear response of the vacuum to strong electromagnetic fields of macroscopic extent. This fundamental tenet has remained experimentally challenging and is yet to be tested in the laboratory. A particularly distinct signature of the resulting optical activity of the quantum vacuum is vacuum birefringence. This offers an excellent opportunity for a precision test of nonlinear quantum electrodynamics in an uncharted parameter regime. Recently, the operation of the high-intensity Relativistic Laser at the X-ray Free Electron Laser provided by the Helmholtz International Beamline for Extreme Fields has been inaugurated at the High Energy Density scientific instrument of the European X-ray Free Electron Laser. We make the case that this worldwide unique combination of an X-ray free-electron laser and an ultra-intense near-infrared laser together with recent advances in high-precision X-ray polarimetry, refinements of prospective discovery scenarios and progress in their accurate theoretical modelling have set the stage for performing an actual discovery experiment of quantum vacuum nonlinearity.

In this study, an appropriate visual scoring system for foot-pad dermatitis was validated, considering the histologically measured depth of the inflammation zone and the histopathological grade (no lesion, mild lesion, ulcer). The aim being to evaluate whether the visual, macroscopic scoring of foot-pad dermatitis can represent the histological, microscopic findings. Two hundred Ross 308 broiler chicken feet (birds aged 39-42 fattening days) were collected at a slaughterhouse and scored macroscopically according to a modified version of the Welfare Quality® Assessment Protocol for Poultry. Afterwards, 200 histological slides (one per foot) were prepared, the extent of the inflammation measured and all slides scored by veterinarian pathologists using Michel et al's modified scheme. The statistical relationship between microscopic and macroscopic score and depth of inflammation were estimated via regression models. Increasing macroscopic score was found to be linked with an increase in microscopic score and the depth of inflammation. In particular, feet without lesions and feet with ulcers were identifiable using the macroscopic score. Macroscopic scoring of foot-pad dermatitis can mirror histological findings once certain limitations are taken into account (superficial lesions were not clearly identifiable). Foot-pad dermatitis is considered a useful indicator of animal welfare and our findings suggest that visual, macroscopic scoring could be a practicable assessment tool.

Laser-based compact MeV X-ray sources are useful for a variety of applications such as radiography and active interrogation of nuclear materials. MeV X rays are typically generated by impinging the intense laser onto ~mm-thick high-Z foil. Here, we have characterized such a MeV X-ray source from 120 TW (80 J, 650 fs) laser interaction with a 1 mm-thick tantalum foil. Our measurements show X-ray temperature of 2.5 MeV, flux of 3 × 1012 photons/sr/shot, beam divergence of ~0.1 sr, conversion efficiency of ~1%, that is, ~1 J of MeV X rays out of 80 J incident laser, and source size of 80 m. Our measurement also shows that MeV X-ray yield and temperature is largely insensitive to nanosecond laser contrasts up to 10−5. Also, preliminary measurements of similar MeV X-ray source using a double-foil scheme, where the laser-driven hot electrons from a thin foil undergoing relativistic transparency impinging onto a second high-Z converter foil separated by 50–400 m, show MeV X-ray yield more than an order of magnitude lower compared with the single-foil results.

Human mesenchymal stem cells were reseeded in decellularized human bone subject to a controlled mechanical loading to create a bone-on-chip that was cultured for over 26 months. The cell morphology and their secretome were characterized using immunohistochemistry and in situ immunofluorescence under confocal microscopy. The presence of stem cell derived osteocytes was confirmed at 547 days. Different cell populations were identified. Some cells were connected by long processes and formed a network. Comparison of the MSCs in vitro reorganization and calcium response to in situ mechanical stimulation were compared to MLOY4 cells reseeded on human bone. The bone-on-chip produced an ECM of which the strength was nearly a quarter of native bone after 109 days and that contained calcium minerals at 39 days and type I collagen at 256 days. The cytoplasmic calcium concentration variations seemed to adapt to the expected in vivo mechanical load at the successive stages of cell differentiation in agreement with studies using fluid shear flow stimulation. Some degree of bone-like formation over a long period of time with the formation of a newly formed matrix was observed.

The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

The SkyMapper Transient survey (SMT) is exploring variability in the southern sky by performing (a) a rolling search to discover and study supernovæ, and (b) a Target of Opportunity programme that uses the robotic SkyMapper Telescope at Siding Spring Observatory. The supernova survey is obtaining a non-targeted sample of Type Ia supernovæ (SNe Ia) at low redshifts, z < 0.1, and studying other interesting transients found with the search strategy. We have a Target of Opportunity programme with an automatic response mechanism to search for optical counterparts to gravitational-wave and fast radio-burst events; it benefits from SkyMapper’s large field of view of 5.7 sq. deg. and a rapid data reduction pipeline.

We present first results of the SMT survey. The SMT pipeline can process and obtain potential candidates within 12 hours of observation. It disentangles real transients from processing artefacts using a machine-learning algorithm. To date, SMT has discovered over 60 spectroscopically confirmed supernovæ, several peculiar objects, and over 40 SNe Ia including one (SNIa 2016hhd) which was found within the first few days of explosion. We have also participated in searches for optical counterparts of gravitational waves, fast radio bursts and other transients, and have published observations of the optical counterpart of the gravitational-wave event GW170817. We also participate in coordinated observations with the Deeper Wider Faster programme, and the Kepler K2 cosmology project.

The SkyMapper 1.3 m telescope at Siding Spring Observatory has now begun regular operations. Alongside the Southern Sky Survey, a comprehensive digital survey of the entire southern sky, SkyMapper will carry out a search for supernovae and other transients. The search strategy, covering a total footprint area of ~2 000 deg2 with a cadence of ⩽5 d, is optimised for discovery and follow-up of low-redshift type Ia supernovae to constrain cosmic expansion and peculiar velocities. We describe the search operations and infrastructure, including a parallelised software pipeline to discover variable objects in difference imaging; simulations of the performance of the survey over its lifetime; public access to discovered transients; and some first results from the Science Verification data.

Approximately half of the variation in wellbeing measures overlaps with variation in personality traits. Studies of non-human primate pedigrees and human twins suggest that this is due to common genetic influences. We tested whether personality polygenic scores for the NEO Five-Factor Inventory (NEO-FFI) domains and for item response theory (IRT) derived extraversion and neuroticism scores predict variance in wellbeing measures. Polygenic scores were based on published genome-wide association (GWA) results in over 17,000 individuals for the NEO-FFI and in over 63,000 for the IRT extraversion and neuroticism traits. The NEO-FFI polygenic scores were used to predict life satisfaction in 7 cohorts, positive affect in 12 cohorts, and general wellbeing in 1 cohort (maximal N = 46,508). Meta-analysis of these results showed no significant association between NEO-FFI personality polygenic scores and the wellbeing measures. IRT extraversion and neuroticism polygenic scores were used to predict life satisfaction and positive affect in almost 37,000 individuals from UK Biobank. Significant positive associations (effect sizes <0.05%) were observed between the extraversion polygenic score and wellbeing measures, and a negative association was observed between the polygenic neuroticism score and life satisfaction. Furthermore, using GWA data, genetic correlations of -0.49 and -0.55 were estimated between neuroticism with life satisfaction and positive affect, respectively. The moderate genetic correlation between neuroticism and wellbeing is in line with twin research showing that genetic influences on wellbeing are also shared with other independent personality domains.

Anxiety sensitivity (AS), the belief that anxious arousal is harmful, is a malleable risk factor that has been implicated in anxiety and depression symptoms in adolescents. Although there is some evidence that adolescents possess distinct developmental trajectories, few studies have explored this topic. This study examined the developmental trajectory of AS in 248 adolescents (M age = 11.0 years, SD = 0.82; 56% male) across 6 years, beginning when children were age 11. This study also examined the influence of AS trajectories on anxiety and depression at age 16. Finally, this study examined the utility of AS classes in identifying anxiety and depression growth. Three AS classes were found, described by normative-stable, high-stable, and high-unstable trajectories. Adolescents in the high-stable and the high-unstable AS classes had higher levels of anxiety and depression at age 16 than did adolescents in the normative-stable AS class. In addition, the anxiety and depression trajectories fit by AS class mirrored the AS class trajectories. These findings suggest three AS trajectories can be identified in adolescents. These trajectories are discussed in relation to a developmental perspective of AS.

Exposure to animal livestock has been linked to zoonotic transmission, especially of gastrointestinal pathogens. Exposure to animals may contribute to chronic asymptomatic intestinal infection, environmental enteropathy and child under-nutrition in low-income settings. We conducted a cohort study to explore the effect of exposure to cows on growth and endemic diarrhoea in children aged <5 years in a rural, low-income setting in the Indian state of Odisha. The study enrolled 1992 households with 2739 children. Height measurements were available for 824 children. Exposure to cows was measured as (1) the presence of a cowshed within or outside the compound, (2) the number of cows owned by a household, and (3) the number of cowsheds located within 50 m of a household. In a sub-study of 518 households, fly traps were used to count the number of synanthropic flies that may act as vectors for gastrointestinal pathogens. We found no evidence that environmental exposure to cows contributes to growth deficiency in children in rural India, neither directly by affecting growth, nor indirectly by increasing the risk of diarrhoea. We found no strong evidence that the presence of a cowshed increased the number synanthropic flies in households.