Plenoptic particle image velocimetry and surface pressure measurements were used to analyse the early development of leading-edge vortices (LEVs) created by a flat-plate wing of aspect ratio 2 rolling in a uniform flow parallel to the roll axis. Four cases were constructed by considering two advance coefficients, $J=0.54$ and 1.36, and two wing radii of gyration, $R_g/c=2.5$ and 3.25. In each case, the wing pitch angle was articulated such as to achieve an angle of attack of $33^{\circ }$ at the radius of gyration of the wing. The sources and sinks of vorticity were quantified for a chordwise rectangular control region, using a vorticity transport framework in a non-inertial coordinate system attached to the wing. Within this framework, terms associated with Coriolis acceleration provide a correction to tilting and spanwise convective fluxes measured in the rotating frame and, for the present case, have insignificant values. For the baseline case ($J=0.54, R_g/c=3.25$), three distinct spanwise regions were observed within the LEV, with distinct patterns of vortex evolution and vorticity transport mechanisms in each region. Reducing the radius of gyration to $R_g/c=2.5$ resulted in a more stable vortex with the inboard region extending over a broader spanwise range. Increasing advance ratio eliminated the conical vortex, resulting in transport processes resembling the mid-span region of the baseline case. Although the circulation of the LEV system was generally stronger at the larger advance coefficient, the shear-layer contribution was diminished.

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.

Optically luminous early type galaxies host X-ray luminous, hot atmospheres. These hot atmospheres, which we refer to as coronae, undergo the same cooling and feedback processes as are commonly found in their more massive cousins, the gas rich atmospheres of galaxy groups and galaxy clusters. In particular, the hot coronae around galaxies radiatively cool and show cavities in X-ray images that are filled with relativistic plasma originating from jets powered by supermassive black holes (SMBH) at the galaxy centers. We discuss the SMBH feedback using an X-ray survey of early type galaxies carried out using Chandra X-ray Observatory observations. Early type galaxies with coronae very commonly have weak X-ray active nuclei and have associated radio sources. Based on the enthalpy of observed cavities in the coronae, there is sufficient energy to “balance” the observed radiative cooling. There are a very few remarkable examples of optically faint galaxies that are 1) unusually X-ray luminous, 2) have large dark matter halo masses, and 3) have large SMBHs (e.g., NGC4342 and NGC4291). These properties suggest that, in some galaxies, star formation may have been truncated at early times, breaking the simple scaling relations.

We describe the motivation and design details of the ‘Phase II’ upgrade of the Murchison Widefield Array radio telescope. The expansion doubles to 256 the number of antenna tiles deployed in the array. The new antenna tiles enhance the capabilities of the Murchison Widefield Array in several key science areas. Seventy-two of the new tiles are deployed in a regular configuration near the existing array core. These new tiles enhance the surface brightness sensitivity of the array and will improve the ability of the Murchison Widefield Array to estimate the slope of the Epoch of Reionisation power spectrum by a factor of ∼3.5. The remaining 56 tiles are deployed on long baselines, doubling the maximum baseline of the array and improving the array u, v coverage. The improved imaging capabilities will provide an order of magnitude improvement in the noise floor of Murchison Widefield Array continuum images. The upgrade retains all of the features that have underpinned the Murchison Widefield Array’s success (large field of view, snapshot image quality, and pointing agility) and boosts the scientific potential with enhanced imaging capabilities and by enabling new calibration strategies.

This Research Communication describes an investigation of the nutritional depletion of total mixed rations (TMR) by pest birds. We hypothesized that species-specific bird depredation of TMR can alter the nutritional composition of the ration and that these changes can negatively impact the performance of dairy cows. Blackbirds selected the high energy fraction of the TMR (i.e., flaked corn) and reduced starch, crude fat and total digestible nutrients during controlled feeding experiments. For Holsteins producing 37·1 kg of milk/d, dairy production modeling illustrated that total required net energy intake (NEI) was 35·8 Mcal/d. For the reference TMR unexposed to blackbirds and the blackbird-consumed TMR, NEI supplied was 41·2 and 37·8 Mcal/d, and the resulting energy balance was 5·4 and 2·0 Mcal/d, respectively. Thus, Holsteins fed the reference and blackbird-consumed TMR were estimated to gain one body condition score in 96 and 254 d, and experience daily weight change due to reserves of 1·1 and 0·4 kg/d, respectively. We discuss these results in context of an integrated pest management program for mitigating the depredation caused by pest birds at commercial dairies.

We describe the design and performance of the Engineering Development Array, which is a low-frequency radio telescope comprising 256 dual-polarisation dipole antennas working as a phased array. The Engineering Development Array was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array precursor technology and expertise, specifically from the Murchison Widefield Array radio telescope. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the Engineering Development Array’s receiver temperature as a function of frequency. The Engineering Development Array is shown to be sky-noise limited over most of the frequency range measured between 60 and 240 MHz. By using the Engineering Development Array in interferometric mode with the Murchison Widefield Array, we used calibrated visibilities to measure the absolute sensitivity of the array. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature. The results demonstrate the practicality and feasibility of using Murchison Widefield Array-style precursor technology for Square Kilometre Array-scale stations. The modular architecture of the Engineering Development Array allows upgrades to the array to be rolled out in a staged approach. Future improvements to the Engineering Development Array include replacing the second stage beamformer with a fully digital system, and to transition to using RF-over-fibre for the signal output from first stage beamformers.

Greenhouse and field experiments were conducted to evaluate early postemergence (POST) tank mixtures of SAN 582 with fluazifop-P, imazethapyr, or sethoxydim. In the greenhouse, SAN 582 synergistically improved barnyardgrass, broadleaf signalgrass, and johnsongrass control from imazethapyr and sethoxydim. Half-rates of imazethapyr and sethoxydim tank-mixed with SAN 582 controlled grass weeds as well as full rates of either herbicide applied alone. Grass weed control with imazethapyr increased up to 40% with the addition of SAN 582. In field experiments, SAN 582 increased grass control with imazethapyr to a lesser degree than observed in the greenhouse. In a multispecies study, grass weed control increased up to 15% when SAN 582 was tank-mixed with a reduced rate of imazethapyr, although the full rate of imazethapyr applied POST with or without SAN 582 controlled grass weeds 80% or less. The combination of SAN 582 with sethoxydim was synergistic for barnyardgrass and johnsongrass control in this experiment. When applied POST in soybean, SAN 582 plus fluazifop-P or sethoxydim controlled barnyardgrass throughout the season better than a single POST application of a graminicide.

Global expansion in the cultivation of genetically engineered (GE) crops has raised concerns about the adventitious presence of GE seeds in non-GE and organic products. Flax is the second most important oilseed crop in western Canada and is currently being evaluated as a potential platform for the production of bio-products. Before transgenic flax is released for commercial production, mitigation measures must be identified to reduce the adventitious presence in subsequent crops. To quantify adventitious presence of volunteer flax in spring wheat and to identify the efficacy of herbicide treatments on mitigating volunteer flax adventitious presence, research was conducted at four locations during 2005 and 2006 in central Alberta. To simulate artificial volunteer populations, flax was seeded prior to wheat at a target population of 150 plants m−2. In the untreated control, volunteer flax seed yield was 135 kg ha−1, which resulted in adventitious presence of 8.57% in spring wheat. When left uncontrolled, volunteer flax reduced wheat yields ∼57% and resulted in volunteer flax seed production of 4,755 seeds m−2. A single PRE treatment of glyphosate or glyphosate plus tribenuron reduced volunteer flax density from 39 to 4 and 6 plants m−2, respectively, seed production from 4,755 to < 58 seeds m−2, and volunteer flax seed viability from 55 to < 40%. POST herbicides, fluroxypyr plus MCPA and fluroxypyr plus 2,4-D, reduced volunteer flax seed production as low as 0.6 and 0.0 seeds m−2, respectively, adventitious presence to 0.64 and 0.03%, respectively, and seed viability to ≤ 10%. Combination of glyphosate applied PRE followed by fluroxypyr plus 2,4-D or by thifensulfuron plus tribenuron plus quinclorac applied POST reduced adventitious presence of volunteer flax in wheat to near 0%. These treatment combinations were also effective for reducing volunteer flax fecundity to 0.0 and 7.1 seeds m−2, respectively, and volunteer flax seed viability to 0 and 5%, respectively. This study demonstrated that with effective mitigation strategies, seed mediated gene flow from GE volunteer flax can be reduced.

Johnsongrass populations that are resistant to 5-enolpyruvyl-3-shikimate synthase (EPSPS)–, acetyl coenzyme A carboxylase (ACCase)–, or acetolactate synthase (ALS)–inhibiting herbicides are increasingly common throughout the midsouth. Three trials were conducted in 2012, 2013, and 2014 in Fayetteville, AR and Alexandria, LA to evaluate strategies with and without ALS- and ACCase inhibitors for management of rhizomatous johnsongrass in the absence of glyphosate. Fluometuron or fluometuron plus pyrithiobac applied PRE followed by (fb) EPOST, MPOST, and LAYBY tank mixtures containing multiple effective mechanisms of action (MOA) controlled johnsongrass at least 90%. Simplifying the program by removing a herbicide or eliminating an application timing reduced control, and increased vegetative and sexual reproduction of johnsongrass. To manage severe infestations or escapes glufosinate plus clethodim fb glufosinate plus clethodim or clethodim plus pyrithiobac fb clethodim) effectively controlled 15-cm johnsongrass. However, johnsongrass control was reduced when ALS and ACCase inhibitors were tank mixed, especially for the second POST application, compared to ACCase inhibitors alone. Effective herbicide programs are available to growers to control johnsongrass in the absence of glyphosate, but the use of PRE herbicides followed by multiple applications of POST herbicides is critical for successful management.

During 1990 we surveyed the southern sky using a multi-beam receiver at frequencies of 4850 and 843 MHz. The half-power beamwidths were 4 and 25 arcmin respectively. The finished surveys cover the declination range between +10 and −90 degrees declination, essentially complete in right ascension, an area of 7.30 steradians. Preliminary analysis of the 4850 MHz data indicates that we will achieve a five sigma flux density limit of about 30 mJy. We estimate that we will find between 80 000 and 90 000 new sources above this limit. This is a revised version of the paper presented at the Regional Meeting by the first four authors; the surveys now have been completed.

Graphene-covered copper surfaces have been exposed to borazine, (BH)3(NH)3, with the resulting surfaces characterized by low-energy electron microscopy. Although the intent of the experiment was to form hexagonal boron nitride (h-BN) on top of the graphene, such layers were not obtained. Rather, in isolated surface areas, h-BN is found to form μm-size islands that substitute for the graphene. Additionally, over nearly the entire surface, the properties of the layer that was originally graphene is observed to change in a manner that is consistent with the formation of a mixed h-BN/graphene alloy, i.e., h-BNC alloy. Furthermore, following the deposition of the borazine, a small fraction of the surface is found to consist of bare copper, indicating etching of the overlying graphene. The inability to form h-BN layers on top of graphene is discussed in terms of the catalytic behavior of the underlying copper surface and the decomposition of the borazine on top of the graphene.