Dual-band reflector feed system for classical Cassegrain radio telescopes

1993 ◽  
Vol 41 (3) ◽  
pp. 325-332 ◽  
Author(s):  
R.T.K. Jaldehag ◽  
P.-S. Kildal ◽  
B.O. Ronnang
Keyword(s):  
Dual Band ◽  
Radio Telescopes ◽  
Feed System

The Role of VLBI in the Establishment of Coordinate Systems

1975 ◽  
Vol 26 ◽  
pp. 293-295 ◽  
Author(s):  
I. Zhongolovitch
Keyword(s):  
General Solution ◽  
Future Development ◽  
Rational Approach ◽  
Radio Telescopes ◽  
Coordinate Systems ◽  
Tectonic Plates ◽  
Astronomical Observations ◽  
Optical Instruments ◽  
Fundamental Polyhedron

Considering the future development and general solution of the problem under consideration and also the high precision attainable by astronomical observations, the following procedure may be the most rational approach:1. On the main tectonic plates of the Earth’s crust, powerful movable radio telescopes should be mounted at the same points where standard optical instruments are installed. There should be two stations separated by a distance of about 6 to 8000 kilometers on each plate. Thus, we obtain a fundamental polyhedron embracing the whole Earth with about 10 to 12 apexes, and with its sides represented by VLBI.

The Current Situation in Chemical Stabilization of Biological Materials

1972 ◽  
Vol 30 ◽  
pp. 132-133
Author(s):  
John H. Luft
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Osmium Tetroxide ◽  
Molecular Level ◽  
Cross Linking ◽  
Chemical Stabilization ◽  
Specimen Preparation ◽  
Sufficient Condition ◽  
Radio Telescopes

With information processing devices such as radio telescopes, microscopes or hi-fi systems, the quality of the output often is limited by distortion or noise introduced at the input stage of the device. This analogy can be extended usefully to specimen preparation for the electron microscope; fixation, which initiates the processing sequence, is the single most important step and, unfortunately, is the least well understood. Although there is an abundance of fixation mixtures recommended in the light microscopy literature, osmium tetroxide and glutaraldehyde are favored for electron microscopy. These fixatives react vigorously with proteins at the molecular level. There is clear evidence for the cross-linking of proteins both by osmium tetroxide and glutaraldehyde and cross-linking may be a necessary if not sufficient condition to define fixatives as a class.

Gas to Liquid Chemical Feed System Conversion at Seven Wastewater Treatment Plants

2000 ◽  
Vol 2000 (2) ◽  
pp. 495-507
Author(s):  
J. Andrew Landrum ◽  
David M. Murbach ◽  
Bruce Husselbee ◽  
Mardane McLemore
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Feed System ◽  
Liquid Chemical ◽  
Gas To Liquid

One Step Short of Life

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Liquid Water ◽  
Radio Telescopes ◽  
Speed Of Light ◽  
Extraterrestrial Life ◽  
True Nature ◽  
One Step ◽  
New Strategies ◽  
Present Focus

This chapter briefly reviews some the challenges encountered in the search for extraterrestrial life. So far, no signs of extraterrestrial life have been found. The search started with radio telescopes, looking for technology-based civilizations, but new strategies have emerged that take on the primary challenges in this search: the enormous distances to exoplanets and the question of the true nature of life. The author outlines the development of new tools for the search, and why the present focus is on Earth-sized exoplanets with a potential for liquid water on their surfaces. Not having been visited by an alien civilization presents us with a paradox: if life develops as quickly elsewhere as on Earth, then why have we not been contacted? Is the speed of light too slow to cross interstellar distances, is life intrinsically rare, or should we conclude that civilizations are intrinsically short-lived?

scholarly journals Variable Radio Emission from X-Ray Sources

1971 ◽  
Vol 15 ◽  
pp. 173-175 ◽  
Author(s):  
L. L. E. Braes ◽  
G. K. Miley
Keyword(s):  
Radio Emission ◽  
Aperture Synthesis ◽  
Electromagnetic Spectrum ◽  
Radio Telescopes ◽  
Low Resolution ◽  
X Ray ◽  
Synthesis Technique ◽  
Variable Radio

Dr. KELLOGG has just described some exciting new observations of X-ray sources made with the UHURU satellite. We shall now move some nine orders of magnitude in wavelength to the opposite end of the electromagnetic spectrum and report measurements of weak radio emission from some of the objects he mentioned. For the detection of weak sources most radio telescopes are not noise limited, but are confusion limited by their low resolution. The aperture synthesis technique minimizes this problem because it enables one to pinpoint the position of weak sources to the order of one second of arc.

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