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The Commensal Real-time Australian Square Kilometre Array Pathfinder Fast Transients survey is the first extensive astronomical survey using phased array feeds. Since January 2017, it has been searching for fast radio bursts in fly’s eye mode. Here, we present a calculation of the sensitivity and total exposure of the survey that detected the first 20 of these bursts, using the pulsars B1641-45 and B0833-45 as calibrators. The beamshape, antenna-dependent system noise, and the effects of radio-frequency interference and fluctuations during commissioning are quantified. Effective survey exposures and sensitivities are calculated as a function of the source counts distribution. Statistical ‘stat’ and systematics ‘sys’ effects are treated separately. The implied fast radio burst rate is significantly lower than the 37 sky−1 day−1 calculated using nominal exposures and sensitivities for this same sample by Shannon et al. (2018). At the Euclidean (best-fit) power-law index of −1.5 (−2.2), the rate is
(sys) ± 3.6 (stat) sky−1 day−1 (
(sys) ± 2.8 (stat) sky−1 day−1) above a threshold of 56.6 ± 6.6(sys) Jy ms (40.4 ± 1.2(sys) Jy ms). This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.
To date, there has been no published textbook which takes into account changing sociolinguistic dynamics that have influenced South African society. Multilingualism and Intercultural Communication breaks new ground in this arena. The scope of this book ranges from macro-sociolinguistic questions pertaining to language policies and their implementation (or non-implementation) to micro-sociolinguistic observations of actual language-use in verbal interaction, mainly in multilingual contexts of Higher Education (HE). There is a gradual move for the study of language and culture to be taught in the context of (professional) disciplines in which they would be used, for example, Journalism and African languages, Education and African languages, etc. The book caters for this growing market. Because of its multilingual nature, it caters to English and Afrikaans language speakers, as well as the Sotho and Nguni language groups – the largest languages in South Africa [and also increasingly used in the context of South African Higher Education]. It brings together various inter-linked disciplines such as Sociolinguistics and Applied Language Studies, Media Studies and Journalism, History and Education, Social and Natural Sciences, Law, Human Language Technology, Music, Intercultural Communication and Literary Studies. The unique cross-cutting disciplinary features of the book will make it a must-have for twenty-first century South African students and scholars and those interested in applied language issues.
We describe the performance of the Boolardy Engineering Test Array, the prototype for the Australian Square Kilometre Array Pathfinder telescope. Boolardy Engineering Test Array is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarisation beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of Boolardy Engineering Test Array’s performance: sensitivity, beam characteristics, polarimetric properties, and image quality. We summarise the astronomical science that it has produced and draw lessons from operating Boolardy Engineering Test Array that will be relevant to the commissioning and operation of the final Australian Square Kilometre Array Path telescope.
An unlinked anonymous study was conducted to estimate the prevalence of hepatitis C virus (HCV) infection in emergency department (ED) attendees at a London Hospital. Nine hundred and ninety-seven samples collected over a 12-day period were tested for HCV antibody (Ab) and reactive samples were further tested for HCV RNA. The HCV seroprevalence was 2·6% (26/997) with 1·2% (12/997) HCV RNA positive. A peak HCV RNA-positive prevalence of 4·8% (3/63) was found in males aged 35–44 years, this was compared to 0% (0/136) in males aged <35 years (P = 0·0614) and 1·4% (4/278) in males aged ⩾45 years (P = 0·2415). Assuming the cost for HCV Ab is £6 and HCV RNA is £40 per test, screening ED attendees aged 25–54 years would cost £360 per viraemic infection and identify 82% of those who were HCV RNA positive, yielding the most favourable cost/benefit ratio. HCV screening of ED attendees aged 25–54 years in this population could be an effective way of identifying patients and limit onward transmission.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
Fibrin hydrogels are an exciting platform for cell-based therapies, as they contain necessary cues for adhesion, can be remodeled by entrapped cells, and the biophysical properties can be modified with a plethora of strategies. Furthermore, fibrin acts as a provisional matrix in vivo for tissue regeneration. While the majority of studies seek to manipulate fibrin gel properties by changing the concentration of clotting proteins, these studies highlight our capacity to change bulk stiffness and fiber properties by supplementing the solutions with sodium chloride (NaCl). Physical properties including fiber thickness, porosity, compressive modulus, and fluid uptake capacity were dependent on NaCl content, with gels containing 2.60% (w/v) NaCl exhibiting compressive moduli threefold higher than gels without NaCl. These material properties, in turn, affected the gel morphology along with the osteogenic and pro-angiogenic response of entrapped mesenchymal stem/stromal cells (MSCs). The osteoconductivity of fibrin gels can be enhanced by inclusion of apatite-coated polymer substrata to nucleate mineral, while the efficacy of engineered fibrin gels to simultaneously deploy small molecules with cells to enhance endogenous angiogenic potential has been demonstrated. Collectively, these data demonstrate the broad capacity of engineered fibrin gels to regulate function of entrapped cells for use in tissue engineering and regenerative medicine.