Success in marriage markets has lasting impacts on women's wellbeing. By arranging marriages, parents exert financial and social powers to influence spouse characteristics and ensure optimal marriages. While arranging marriages is a major focus of parental investment, marriage decisions are also a source of conflict between parents and daughters in which parents often have more power. The process of market integration may alter parental investment strategies, however, increasing children's bargaining power and reducing parents’ influence over children's marriage decisions. We use data from a market integrating region of Bangladesh to (a) describe temporal changes in marriage types, (b) identify which women enter arranged marriages and (c) determine how market integration affects patterns of arranged marriage. Most women's marriages were arranged, with love marriages more recent. We found few predictors of who entered arranged vs. love marriages, and family-level market integration did not predict marriage type at the individual level. However, based on descriptive findings, and findings relating women's and fathers’ education to groom characteristics, we argue that at the society-level market integration has opened a novel path in which daughters use their own status, gained via parental investments, to facilitate good marriages under conditions of reduced parental assistance or control.

The redshifted cosmological 21-cm signal emitted by neutral hydrogen during the first billion years of the universe is much fainter relative to other galactic and extragalactic radio emissions, posing a great challenge towards detection of the signal. Therefore, precise instrumental calibration is a vital prerequisite for the success of radio interferometers such as the Murchison Widefield Array (MWA), which aim for a 21-cm detection. Over the previous years, novel calibration techniques targeting the power spectrum paradigm of EoR science have been actively researched and where possible implemented. Some of these improvements, for the MWA, include the accuracy of sky models used in calibration and the treatment of ionospheric effects, both of which introduce unwanted contamination to the EoR window. Despite sophisticated non-traditional calibration algorithms being continuously developed over the years to incorporate these methods, the large datasets needed for EoR measurements require high computational costs, leading to trade-offs that impede making use of these new tools to maximum benefit. Using recently acquired computation resources for the MWA, we test the full capabilities of the state-of-the-art calibration techniques available for the MWA EoR project, with a focus on both direction-dependent and direction-independent calibration. Specifically, we investigate improvements that can be made in the vital calibration stages of sky modelling, ionospheric correction, and compact source foreground subtraction as applied in the hybrid foreground mitigation approach (one that combines both foreground subtraction and avoidance). Additionally, we investigate a method of ionospheric correction using interpolated ionospheric phase screens and assess its performance in the power spectrum space. Overall, we identify a refined RTS calibration configuration that leads to an at least 2 factor reduction of the EoR window power contamination at the $0.1 \; \textrm{hMpc}^{-1}$ scale. The improvement marks a step further towards detecting the 21-cm signal using the MWA and the forthcoming SKA low telescope.

To overcome grass supply shortages on the main grazing block, some pasture-based dairy farmers are using zero-grazing (also known as ‘cut and carry’), whereby cows are periodically housed and fed fresh grass harvested from external land blocks. To determine the effect of zero-grazing on cow performance, two early-lactation experiments were conducted with autumn and spring-calving dairy cows. Cows were assigned to one of two treatments in a randomized complete block design. The two treatments were zero-grazing (ZG) and grazing (G). The ZG group were housed and fed zero-grazed grass, while the G group grazed outdoors at pasture. Both treatments were fed perennial ryegrass (Lolium perenne L.) from the same paddock. In experiment 1, 24 Holstein Friesian cows (n = 12) were studied over a 35-day experimental period in autumn and offered fresh grass, grass silage, ground maize and concentrates. In experiment 2, 30 Holstein Friesian cows (n = 15) were studied over a 42-day experimental period and offered fresh grass and concentrates. Average dry matter intake and milk yield was similar for ZG and G in both experiments. Likewise, ZG did not have an effect on milk composition, body condition or locomotion. Zero-grazing had no effect on total nitrogen excretion or nitrogen utilization efficiency in either experiment, or on rumen pH and ammonia concentration in experiment 1. While zero-grazing may enable farmers to supply fresh grass to early-lactation cows in spring and autumn, results from this study suggest that there are no additional benefits to cow performance in comparison to well-managed grazed grass.

The earliest airborne geophysical campaigns over Antarctica and Greenland in the 1960s and 1970s collected ice penetrating radar data on 35 mm optical film. Early subglacial topographic and englacial stratigraphic analyses of these data were foundational to the field of radioglaciology. Recent efforts to digitize and release these data have resulted in geometric and ice-thickness analysis that constrain subsurface change over multiple decades but stop short of radiometric interpretation. The primary challenge for radiometric analysis is the poorly-characterized compression applied to Z-scope records and the sparse sampling of A-scope records. Here, we demonstrate the information richness and radiometric interpretability of Z-scope records. Z-scope pixels have uncalibrated fast-time, slow-time, and intensity scales. We develop approaches for mapping each of these scales to physical units (microseconds, seconds, and signal to noise ratio). We then demonstrate the application of this calibration and analysis approach to a flight in the interior of East Antarctica with subglacial lakes and to a reflight of an East Antarctic ice shelf that was observed by both archival and modern radar. These results demonstrate the potential use of Z-scope signals to extend the baseline of radiometric observations of the subsurface by decades.

One of the principal systematic constraints on the Epoch of Reionisation (EoR) experiment is the accuracy of the foreground calibration model. Recent results have shown that highly accurate models of extended foreground sources, and including models for sources in both the primary beam and its sidelobes, are necessary for reducing foreground power. To improve the accuracy of the source models for the EoR fields observed by the Murchison Widefield Array (MWA), we conducted the MWA Long Baseline Epoch of Reionisation Survey (LoBES). This survey consists of multi-frequency observations of the main MWA EoR fields and their eight neighbouring fields using the MWA Phase II extended array. We present the results of the first half of this survey centred on the MWA EoR0 observing field (centred at RA (J2000) $0^\mathrm{h}$ , Dec (J2000) $-27^{\circ}$ ). This half of the survey covers an area of 3 069 degrees $^2$ , with an average rms of 2.1 mJy beam–1. The resulting catalogue contains a total of 80 824 sources, with 16 separate spectral measurements between 100 and 230 MHz, and spectral modelling for 78 $\%$ of these sources. Over this region we estimate that the catalogue is 90 $\%$ complete at 32 mJy, and 70 $\%$ complete at 10.5 mJy. The overall normalised source counts are found to be in good agreement with previous low-frequency surveys at similar sensitivities. Testing the performance of the new source models we measure lower residual rms values for peeled sources, particularly for extended sources, in a set of MWA Phase I data. The 2-dimensional power spectrum of these data residuals also show improvement on small angular scales—consistent with the better angular resolution of the LoBES catalogue. It is clear that the LoBES sky models improve upon the current sky model used by the Australian MWA EoR group for the EoR0 field.

The Epoch of Reionisation (EoR) is the period within which the neutral universe transitioned to an ionised one. This period remains unobserved using low-frequency radio interferometers, which target the 21 cm signal of neutral hydrogen emitted in this era. The Murchison Widefield Array (MWA) radio telescope was built with the detection of this signal as one of its major science goals. One of the most significant challenges towards a successful detection is that of calibration, especially in the presence of the Earth’s ionosphere. By introducing refractive source shifts, distorting source shapes, and scintillating flux densities, the ionosphere is a major nuisance in low-frequency radio astronomy. We introduce sivio, a software tool developed for simulating observations of the MWA through different ionospheric conditions, which is estimated using thin screen approximation models and propagated into the visibilities. This enables us to directly assess the impact of the ionosphere on observed EoR data and the resulting power spectra. We show that the simulated data captures the dispersive behaviour of ionospheric effects. We show that the spatial structure of the simulated ionospheric media is accurately reconstructed either from the resultant source positional offsets or from parameters evaluated during the data calibration procedure. In turn, this will inform on the best strategies of identifying and efficiently eliminating ionospheric contamination in EoR data moving into the Square Kilometre Array era.

This research communication addressed the hypothesis that late lactation cows offered an oat-grain-based supplement or a high level of α-TOC supplementation at pasture would have improved milk composition and processability. Over a grazing period of 49 d, 48 Holstein Friesian dairy cows were randomly assigned to one of four dietary treatments. The dietary treatments were: control, pasture only (CTRL), pasture + 2.65 kg DM barley-based concentrate + 350 IU α-TOC/kg (BARLO), pasture + 2.65 kg DM oat-based concentrate + 350 IU α-TOC/kg (OATLO) and pasture + 2.65 kg DM oat-based concentrate + 1050 IU α-TOC/kg (OATHI). Within this randomised complete block design experiment cows were blocked on days in milk (DIM) and balanced for parity, milk yield and composition. Rennet coagulation time (RCT) was reduced in milk from cows offered OATHI compared to CTRL cows and OATLO. Concentration of conjugated linoleic acid (CLA) was increased by OATHI compared to OATLO and in OATLO compared to CTRL. Supplementation with OATHI reduced individual saturated fatty acids (SFAs) in milk compared to OATLO. In conclusion, supplementing grazing dairy cows with an oat-based supplement improved total milk CLA concentration compared to pasture only. Offering a high level of α-TOC (2931 IU/d) to dairy cows reduced RCT, individual SFA and increased total CLA concentration of milk compared to a lower α-TOC level (738 IU α-TOC/d).

Precise instrumental calibration is of crucial importance to 21-cm cosmology experiments. The Murchison Widefield Array’s (MWA) Phase II compact configuration offers us opportunities for both redundant calibration and sky-based calibration algorithms; using the two in tandem is a potential approach to mitigate calibration errors caused by inaccurate sky models. The MWA Epoch of Reionization (EoR) experiment targets three patches of the sky (dubbed EoR0, EoR1, and EoR2) with deep observations. Previous work in Li et al. (2018) and (2019) studied the effect of tandem calibration on the EoR0 field and found that it yielded no significant improvement in the power spectrum (PS) over sky-based calibration alone. In this work, we apply similar techniques to the EoR1 field and find a distinct result: the improvements in the PS from tandem calibration are significant. To understand this result, we analyse both the calibration solutions themselves and the effects on the PS over three nights of EoR1 observations. We conclude that the presence of the bright radio galaxy Fornax A in EoR1 degrades the performance of sky-based calibration, which in turn enables redundant calibration to have a larger impact. These results suggest that redundant calibration can indeed mitigate some level of model incompleteness error.

The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low-frequency (80–300 MHz) southern sky. Since beginning operations in mid-2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21 cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together $60+$ programs recorded 20 000 h producing 146 papers to date. In 2016, the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper, we review the major results from the prior operation of the MWA and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes but also include ideas for directions outside these categories.

The Murchison Widefield Array (MWA) is an electronically steered low-frequency (<300 MHz) radio interferometer, with a ‘slew’ time less than 8 s. Low-frequency (∼100 MHz) radio telescopes are ideally suited for rapid response follow-up of transients due to their large field of view, the inverted spectrum of coherent emission, and the fact that the dispersion delay between a 1 GHz and 100 MHz pulse is on the order of 1–10 min for dispersion measures of 100–2000 pc/cm3. The MWA has previously been used to provide fast follow-up for transient events including gamma-ray bursts (GRBs), fast radio bursts (FRBs), and gravitational waves, using systems that respond to gamma-ray coordinates network packet-based notifications. We describe a system for automatically triggering MWA observations of such events, based on Virtual Observatory Event standard triggers, which is more flexible, capable, and accurate than previous systems. The system can respond to external multi-messenger triggers, which makes it well-suited to searching for prompt coherent radio emission from GRBs, the study of FRBs and gravitational waves, single pulse studies of pulsars, and rapid follow-up of high-energy superflares from flare stars. The new triggering system has the capability to trigger observations in both the regular correlator mode (limited to ≥0.5 s integrations) and using the Voltage Capture System (VCS, 0.1 ms integration) of the MWA and represents a new mode of operation for the MWA. The upgraded standard correlator triggering capability has been in use since MWA observing semester 2018B (July–Dec 2018), and the VCS and buffered mode triggers will become available for observing in a future semester.

The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.

We apply two methods to estimate the 21-cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum estimate to be undertaken on the multiple redundantly spaced triangles of antenna tiles, as well as an estimate based on data gridded to the uv-plane. The direct and gridded bispectrum estimators are applied to 21 h of high-band (167–197 MHz; z = 6.2–7.5) data from the 2016 and 2017 observing seasons. Analytic predictions for the bispectrum bias and variance for point-source foregrounds are derived. We compare the output of these approaches, the foreground contribution to the signal, and future prospects for measuring the bispectra with redundant and non-redundant arrays. We find that some triangle configurations yield bispectrum estimates that are consistent with the expected noise level after 10 h, while equilateral configurations are strongly foreground-dominated. Careful choice of triangle configurations may be made to reduce foreground bias that hinders power spectrum estimators, and the 21-cm bispectrum may be accessible in less time than the 21-cm power spectrum for some wave modes, with detections in hundreds of hours.

New fluid inclusion analyses using a range of analytical techniques including quadropole mass spectrometric analyses coupled with gemmological investigations were conducted on rough and gemquality faceted emeralds from the Piteiras Mine, Minas Gerais, Brazil. These data complement those of Rondeau et al. (2003) who also presented analyses of the Piteiras emeralds. Emeralds are found typically as euhedral-to-anhedral crystals disseminated in biotite-phlogopite schist and range from 0.5 to 50 mm long. Emerald mineralization is associated closely with alkaline metasomatized pegmatite bodies, quartz boudin and veins, and talc-chlorite bands. Four types of fluid inclusions are recognized in the emeralds. These include aqueous brine and aqueous carbonic varieties containing one or two liquid phases, along with gas bubbles and/or solid crystals (e.g. carbonates). Primary fluid inclusions in emeralds record salinities of ~4–24 eq. wt.% NaCl and minimum trapping temperatures from ~350 to 480ºC. Combined microthermometry, Raman spectroscopy and crush-leach gas analyses indicate that the mineralizing fluid was an aqueous carbonic brine enriched in reduced volatile species such as CH4, N2, H2S and alkanes. With respect to their optical properties (RI ε = 1.573–1.580; RI ω = 1.580–1.588; birefringence = 0.006–0.008) and specific gravity (2.65–2.78), the Piteiras emeralds fall within the expected range for metasomatic, schist-hosted emeralds.

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.