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Much of the agricultural area in California’s southwestern San Joaquin Valley (SJV) is prone to moisture stress and high soil-salinity conditions. Increased prevalence of glyphosate-resistant (GR) biotypes of junglerice [Echinochloa colona (L.) Link] in these environments and their ecological implications need to be further explored. Studies were conducted on GR and glyphosate-susceptible (GS) biotypes of E. colona to compare the effects of moisture and salinity stress on seed germination and salinity stress alone on growth and seed production. Intraspecific competition between the GR and GS plants was also assessed in a replacement series design experiment. With respect to germination, both biotypes were tolerant to moisture and salinity stress at germination; however, the GR biotype was more tolerant than the GS biotype. Water potential and electrical conductivity (EC) levels that reduced germination by 50% were estimated as −1.5 and −2.3 MPa and 8.5 and 12 dS m−1 for the GS and GR biotypes, respectively. The EC levels that reduced aboveground biomass by 50% were estimated as 9 and 11.5 dS m−1 for the GS and GR biotypes, respectively. Seed production was generally greater in the GR than the GS plants below 10 dS m−1. All plants produced up to 140 seeds plant−1, even at 20 dS m−1. The GR plants were more competitive and produced more aboveground dry biomass and seeds than the GS plants when grown together or alone. In conclusion, differences between these particular GR and GS biotypes to environmental stresses and intraspecific competition were noted that could have ecological implications for their prevalence in the southwestern SJV. The results also suggested that there could be high genetic variability and phenotypic plasticity in E. colona populations in the SJV and further population shifts could occur due to selection pressure from glyphosate.
The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
Our pilot study reports twenty-six cases of resolved chronic otitis media in which the human, cadaveric styloid process was used as an ossicular graft material. A maximum follow-up of one year is presented in this paper. There was no extrusion or rejection of the styloid processes. Hearing improvement with a closure of the air-bone gap to within 10–15 dB. of the pre-operative bone conduction was found in most cases. So far the styloid process has proved to be an ideal ossicular graft though the long-term results are yet to be seen.
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