Over the last years a number of operators have been deploying satellite-based consumer internet access services to reduce the digital divide and capture the market of households not covered by ADSL, cable or wireless broadband. These operators are proposing a step change improvement in the economics of consumer service, with lower terminal costs, broadband access with monthly fees comparable to...

National Aeronautics and Space Administration (NASA) has developed a space-qualified, reprogrammable, Ka-band Software Defined Radio (SDR) to be utilized as part of an onorbit, reconfigurable testbed. The testbed will operate on the truss of the International Space Station beginning in late 2012. Three unique SDRs comprise the testbed, and each radio is compliant to the Space Telecommunications...

NASA’s Deep Space Network (DSN) has been using both 70-m and 34-m reflector antennas to communicate with spacecraft at S-band (2.3 GHz) and X-band (8.45 GHz). To improve the quality of telecommunication and to meet future mission requirements, JPL has been developing 34-m Ka-band (32-GHz) beamwaveguide antennas. Presently, antenna pointing operates in either the open-loop mode with blind pointi...

Dual-Band Reflectarrays Using Microstrip Ring Elements and Their Applications with Various Feeding Arrangements. (August 2006) Chul Min Han, B.S., Korea University Chair of Advisory Committee: Dr. Kai Chang In recent years there has been a growing demand for reduced mass, small launch volume, and, at the same time, high-gain large-aperture antenna systems in modern space-borne applications. Thi...

Carbon isotopically based estimates of CO2 levels have been generated from a record of the photosynthetic fractionation of •3C (-%) in a central equatorial Pacific sediment core that spans the last ~255 ka.

We prove some extension theorems and applications, inspired by the very interesting recent results of Hacon-McKernan [HM1], [HM2] and Takayama [Ta], used in the minimal model program and in turn inspired by fundamental results of Siu. Parts of the proofs we give follow quite closely techniques in [Ka], [HM1], [HM2], and [Laz], which use asymptotic constructions. Related analytic statements are ...

We shall say that an automorphism a is nilpotent or acts nilpotently on a group G if in the holomorph H= [G](a) of G with a, a is a bounded left Engel element, that is, [H, ¿a] = l for some natural number ¿. Here [H, ka] means [H, (k — l)a] with [H, Oa] denoting H. Let G' denote the commutator subgroup [G, G], and let $(G) denote the Frattini subgroup of G. If a is an automorphism of a nilpoten...