Maximum zeros scheduling for satellite switch TDMA

A scheduling technique suitable for preassignment in satellite switched time division multiple access (SS-TDMA) systems is presented. As many uninterrupted bursts as are feasible are transmitted per configuration of the switch matrix. For small switch matrices (up to 6*6) this technique usually requires fewer reconfigurations than previous methods.<>     

Bridging boundaries: CORBA in perspective

Applications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called bridging technologies to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes how client applications can invoke operations on server objects using the services of an intermediary known as an Object Request Broker, or ORB. This article introduces CORBA by describing its key components. It then reviews the boundaries it helps to bridge. It concludes by comparing CORBA with a number of other bridging technologies available today     

Millimeter-Wave Profiled Corrugated Horns for the Quad Cosmic Background Polarization Experiment

In this paper we report on the design and validation process for the profiled corrugated horn antennas, which feed the bolometer array of a cosmology experiment known as QUaD located at the South Pole. This is a cosmic background radiation polarization project, which demands precise knowledge and control of the optical coupling to the signal in order to map the feeble E- and B-polarization mode structure. The system will operate in two millimeter wavelength bands at 100 and 150 GHz. The imaging horn array collects the incoming signal via on-axis front-end optics and a Cassegrain telescope, with a cold stop in front of the array to terminate side-lobe structure at an edge taper of ?20dB. The corrugated horn design process was undertaken using in-house analytical software tools, based on modal scattering, specially developed for millimeter -wave profiled horn antennas. An important part of the instrument development was the validation of the horn design, in particular to verify low edge taper levels and the required well-defined band edges. Suitable feed horn designs were measured and were found to be in excellent agreement with theoretical predictions.     

Internal reflection ellipsometry for real-time monitoring of polyelectrolyte multilayer growth onto tantalum pentoxide

Internal reflection ellipsometry was used for detection of the consecutive coating of two polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA), onto a tantalum pentoxide (Ta₂O₅) substrate until the 10th bilayer. The UV patterned PAH-PAA-multilayer was characterized in air via ellipsometry and atomic force microscopy. Suited optical models enabled the determination of the layer thicknesses in wet and dry states. Linear multilayer formation could be proved by Attenuated Total Reflection — Fourier Transformed Infrared Spectroscopy measurements following the increase of the ν(C=O) band depending on the adsorption of the PAA. Streaming potential measurements after each layer deposition step indicated a change in surface charge after each layer deposition due to the consecutive coating of PAH and PAA. In this article the internal reflection ellipsometry is shown to be a convenient possibility to analyze the modification of a thin transparent Ta₂O₅ substrate.     

Sudden Gains in Cognitive Therapy for Depression: A Replication and Extension.

Of 76 clients receiving 8-20 sessions of cognitive therapy (CT) in a joint university and a national health service clinic, 31 experienced sudden gains that appeared very similar to those first reported in clinical trials of CT by T. Z. Tang and R. J. DeRubeis (1999) and subsequently replicated in other studies. The sudden gains appeared less stable in the present study's more routine clinical practice settings than they were in the clinical trials. Life events did not appear to account for sudden gains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An epitaxial Si/SiO2 superlattice barrier

An epitaxial strain layer Si/SiO₂ superlattice barrier (SLSB) for silicon formed by monolayers of adsorbed oxygen, sandwiched between adjacent thin silicon layers deposited with molecular beam, showed good epitaxy with an effective barrier height of 1.7 eV. Such a barrier should be important for future quantum devices in silicon, as well as new applications in conventional MOS technology.