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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.
For livestock production systems to play a positive role in global food security, the balance between their benefits and disbenefits to society must be appropriately managed. Based on the evidence provided by field-scale randomised controlled trials around the world, this debate has traditionally centred on the concept of economic-environmental trade-offs, of which existence is theoretically assured when resource allocation is perfect on the farm. Recent research conducted on commercial farms indicates, however, that the economic-environmental nexus is not nearly as straightforward in the real world, with environmental performances of enterprises often positively correlated with their economic profitability. Using high-resolution primary data from the North Wyke Farm Platform, an intensively instrumented farm-scale ruminant research facility located in southwest United Kingdom, this paper proposes a novel, information-driven approach to carry out comprehensive assessments of economic-environmental trade-offs inherent within pasture-based cattle and sheep production systems. The results of a data-mining exercise suggest that a potentially systematic interaction exists between ‘soil health’, ecological surroundings and livestock grazing, whereby a higher level of soil organic carbon (SOC) stock is associated with a better animal performance and less nutrient losses into watercourses, and a higher stocking density with greater botanical diversity and elevated SOC. We contend that a combination of farming system-wide trials and environmental instrumentation provides an ideal setting for enrolling scientifically sound and biologically informative metrics for agricultural sustainability, through which agricultural producers could obtain guidance to manage soils, water, pasture and livestock in an economically and environmentally acceptable manner. Priority areas for future farm-scale research to ensure long-term sustainability are also discussed.
Geodetic VLBI experiments are usually conducted at S/X dual bands. Some advantages can be gained at some higher frequency band and in particular at 22 GHz band (K band). We organized a geodetic VLBI experiment on the 16th of February 1991 between Kashima 34m antenna of the Communication Research Laboratory (CRL), in Japan and Medicina 32 m telescope of the Institute of antenna(IRA), in Italy. The phase calibrator was developed using a new “up-conversion” scheme for K band. Data relative to 212 observations of 40 sources were correlated and for 152 scans we obtained correlated amplitudes, delays and delay rates. The r.m.s. residuals have been found to be 100 ps for delays, and 74 fs/s for delay rates. The coherence loss of correlation amplitude becomes large at higher frequency band than 22GHz due to the atmospheric scintillation. The estimated method of the coherence loss was presented. The correlated flux densities at K band evaluated from them were found to be smaller than the ones at X band in general.
Ten ice-sheet models are used to study sensitivity of the Greenland and Antarctic ice sheets to prescribed changes of surface mass balance, sub-ice-shelf melting and basal sliding. Results exhibit a large range in projected contributions to sea-level change. In most cases, the ice volume above flotation lost is linearly dependent on the strength of the forcing. Combinations of forcings can be closely approximated by linearly summing the contributions from single forcing experiments, suggesting that nonlinear feedbacks are modest. Our models indicate that Greenland is more sensitive than Antarctica to likely atmospheric changes in temperature and precipitation, while Antarctica is more sensitive to increased ice-shelf basal melting. An experiment approximating the Intergovernmental Panel on Climate Change’s RCP8.5 scenario produces additional first-century contributions to sea level of 22.3 and 8.1 cm from Greenland and Antarctica, respectively, with a range among models of 62 and 14 cm, respectively. By 200 years, projections increase to 53.2 and 26.7 cm, respectively, with ranges of 79 and 43 cm. Linear interpolation of the sensitivity results closely approximates these projections, revealing the relative contributions of the individual forcings on the combined volume change and suggesting that total ice-sheet response to complicated forcings over 200 years can be linearized.
The Japanese Antarctic Research Expedition (JARE) has set up automatic weather stations at six sites on a 1000 km long traverse route between Syowa station (21 ma.s.l..) and Dome Fuji station (3810 ma.s.l.) since 1993. Large temperature rises in winter were observed several times in this area. There were two patterns of time delay of the temperature rises. One was that the temperature rise at Mizuho station preceded that at other stations, and the other was that the temperature rise at Dome Fuji station preceded the others. The former occurred when a disturbance came from the coast between east Enderby Land and the Amery Ice Shelf and strong winds destroyed the stable inversion layer. The latter occurred when the low-pressure center was near the coast of west Wilkes Land. in this case, temperature rise was caused by adveclion of warm air. The atmospheric pressure at Dome Fuji station and Relay Point oscillated with a period of 0.5 year and amplitude of about 15hPa. The pressure was higher in July and December, and was accompanied by a temperature rise. Fluctuations of hourly air temperature at Dome Fuji station were approximately twice as large as fluctuations at the other sites. The lapse rale of the annual mean temperature increased with elevation, while the monthly lapse rate was largest in April.
This study evaluated the prognosis of idiopathic sudden sensorineural hearing loss when treated with hyperbaric oxygen therapy and intravenous steroids.
The clinical data for 334 patients with idiopathic sudden sensorineural hearing loss treated by hyperbaric oxygen therapy and intravenous steroids at our hospital were retrospectively reviewed. These data included the initial averaged five-frequency hearing level, patient age, interval between onset of symptoms and treatment, vertigo as a complication, and co-existence of diabetes mellitus.
The overall improvement rate was 69.2 per cent, including better improvement (25.5 per cent), good improvement (21.0 per cent) and fair improvement (22.7 per cent).
Hyperbaric oxygen therapy appears to confer a significant additional therapeutic benefit when used in combination with steroid therapy for idiopathic sudden sensorineural hearing loss. If performed early, hyperbaric oxygen therapy may bring about hearing improvement in many patients who are unresponsive to initial therapy.
In order to investigate the distinguishability about the progenitors of FeCCSNe and ECSNe, we calculate the luminosities and spectra of their pre-SN neutrinos and estimate the number of events at neutrino detectors.
We discuss paleoenvironmental changes at the Dae-Am San high moor, located near the Demilitarized Zone at 38°N. This area has been reported to be the only high moor in the Korean peninsula. The 14C age of the bottom sediment (75–80 cm in depth) at this site is about 1900 BP. Since the radiocarbon ages for the intervals at 50–55 cm and 75–80 cm were almost the same, we conclude that the deep layers (55–80 cm) in the high moor were all part of the original soil. Low organic C and N contents in the deeper layers support this inference. The 50–55-cm layer consists of sandy material with very low organic content, suggesting erosion from the surrounding area. The surface layer (0–5 cm) was measured as 190 BP, and the middle layer (30–35 cm) was 870 BP. The bulk sedimentation rate was estimated to be about 0.4 mm yr−1 for the 0–30-cm interval. The δ13C value of organic carbon in the sediments fluctuated with depth. The δ13C profile of the Dae-Am San high moor may be explained by climatic changes which occurred during the Little Ice Age and Medieval Warm Period.
ASCA DSS was intended to carry out unbiased surveys in wide energy range of 0.5-10 keV. The strategy of this project is to survey small sky region with extremely high sensitivity reaching to the source confusion limit of ASCA XRT, in contrast to the Large Sky Survey project (Ueda 1996) which covers much larger sky area with relatively shallow exposure.
The origin of the Cosmic X-ray Background (CXB) radiation has been investigated extensively by soft X-ray deep survey imaging observations with Einstein and ROSAT. In contrast, the lack of telescopes capable of detecting hard X-rays has prevented us from extensive study of the nature of the CXB in the energy range above 2 keV before ASCA.
Starburst galaxies are powered by newly formed massive stars, and are heavily obscured by dust, prohibiting the UV and optical studies. A fine-structure line from Ne+ ion ([Ne II] 12.8 μm) is usually the brightest mid-infrared(MIR) line emitted from starburst galaxies. The [Ne II] line suffers from far less dust extinction than the optical line does, and hence it is often used as a probe for starburst properties of galaxies(Achtermann & Lacy, 1995; Roche et al., 1991). However, the [Ne II] line should not be used as the physical probe unless the relationship between Ne+ abundance and spectral type of the ionizing star is established for very dusty H II regions. To study this, we started the [Ne II] line survey toward dusty ultracompact(UC) H II regions in our Galaxy. The UC H II regions are powered by newly formed early-type stars whose spectral type can be inferred from their radio and far-infrared(FIR) properties.
The X-ray background in the energy range above 2 keV is highly uniform except for an excess component along the Galactic plane. The excess along the plane is considered to be associated with our Galaxy, whereas the rest of the emission is believed to be of extragalactic origin. In this paper, the X-ray background at high Galactic latitude is discussed and is designated as the CXB (cosmic X-ray background) to distinguish it from the Galactic origin.