1,532 research outputs found
Multiwavelength observations of the Be/X-ray binary 4U1145-619
We report optical and infrared observations of the massive X-ray binary
system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be
star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been
monitored from 1993 March to 1996 April. H alpha spectra have been obtained
throughout the same period. We find that both the infrared excess and the
Balmer emission have been in decline throughout the period of observations. A
13 year optical and X-ray history of the source has been collated, revealing a
possible correlation between the optical and X-ray activity. In addition, we
have used u,v,b,y,beta indices, corrected for both circumstellar and
interstellar effects, to calculate the physical parameters of the underlying B
star.Comment: 8 pages postscript. Accepted by MNRA
Integrating Algaculture into Small Wastewater Treatment Plants: Process Flow Options and Life Cycle Impacts
Algaculture has the potential to be a sustainable option for nutrient removal at wastewater treatment plants. The purpose of this study was to compare the environmental impacts of three likely algaculture integration strategies to a conventional nutrient removal strategy. Process modeling was used to determine life cycle inventory data and a comparative life cycle assessment was used to determine environmental impacts. Treatment scenarios included a base case treatment plant without nutrient removal, a plant with conventional nutrient removal, and three other cases with algal unit processes placed at the head of the plant, in a side stream, and at the end of the plant, respectively. Impact categories included eutrophication, global warming, ecotoxicity, and primary energy demand. Integrating algaculture prior to activated sludge proved to be most beneficial of the scenarios considered for all impact categories; however, this scenario would also require primary sedimentation and impacts of that unit process should be considered for implementation of such a system
Results from the Blazar Monitoring Campaign at the Whipple 10m Gamma-ray Telescope
In September 2005, the observing program of the Whipple 10 m gamma-ray
telescope was redefined to be dedicated almost exclusively to AGN monitoring.
Since then the five Northern Hemisphere blazars that had already been detected
at Whipple are monitored routinely each night that they are visible. Thanks to
the efforts of a large number of multiwavelength collaborators, the first year
of this program has been very successful. We report here on the analysis of
Markarian 421 observations taken from November, 2005 to May, 2006 in the
gamma-ray, X-ray, optical and radio bands.Comment: 4 pages; contribution to the 30th International Cosmic Ray
Conference, Merida, Mexico, July 200
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