2,520 research outputs found
A note on Volterra integral equations and topological dynamics
Topological dynamics theory applied to nonlinear Volterra equation
Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo
Circinus X-1 exhibited a bright X-ray flare in late 2013. Follow-up
observations with Chandra and XMM-Newton from 40 to 80 days after the flare
reveal a bright X-ray light echo in the form of four well-defined rings with
radii from 5 to 13 arcminutes, growing in radius with time. The large fluence
of the flare and the large column density of interstellar dust towards Circinus
X-1 make this the largest and brightest set of rings from an X-ray light echo
observed to date. By deconvolving the radial intensity profile of the echo with
the MAXI X-ray lightcurve of the flare we reconstruct the dust distribution
towards Circinus X-1 into four distinct dust concentrations. By comparing the
peak in scattering intensity with the peak intensity in CO maps of molecular
clouds from the Mopra Southern Galactic Plane CO Survey we identify the two
innermost rings with clouds at radial velocity ~ -74 km/s and ~ -81 km/s,
respectively. We identify a prominent band of foreground photoelectric
absorption with a lane of CO gas at ~ -32 km/s. From the association of the
rings with individual CO clouds we determine the kinematic distance to Circinus
X-1 to be kpc. This distance rules out
earlier claims of a distance around 4 kpc, implies that Circinus X-1 is a
frequent super-Eddington source, and places a lower limit of on the Lorentz factor and an upper limit of on the jet viewing angle.Comment: 20 pages, 21 figures, Astrophysical Journal, in prin
Use of anabolic implants in calves to increase weaning weight and backgrounding gains
The main component of the beef industry in South Carolina is cow/calf operations. Recent advances in implant technology are being utilized to help these producers increase weights at time of sale to feedlots. The objective of this study was to determine how the use of anabolic implants in steer calves at 4 mo of age and at weaning altered weight gain at two different farm locations in South Carolina. Steers ( year 1; n= 161, year 2 n=116) from Edisto REC and Simpson REC were randomly allotted into two treatment groups: 1) no implant or 2) implant at 4 mo of age plus implant at weaning. Weights were obtained at implanting, weaning, and the end of backgrounding. Real-time ultrasound measurements of the ribeye area and fat thickness were collected at the end of the backgrounding period. Data were analyzed with the treatment, location, year, and the interaction in the model. Implanting the steers increased (P\u3c0.001) average daily gains from implanting to weaning, weaning to the end of the backgrounding, and overall by 0.36, 0.15, 0.25 lb/hd/d respectively. Implanting also increased ribeye area by 0.34 in2. Weight and gains of the steers differed by location and year but there were no interactions between location, year, and implant treatment. The use of anabolic implants in steer calves at 4 mo of age and then again at weaning helped to increase weight gain, other desirable carcass traits and produced heavier steers for marketing
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