A user oriented computer program for the analysis of microwave mixers, and a study of the effects of the series inductance and diode capacitance on the performance of some simple mixers

A user oriented computer program for analyzing microwave and millimeter wave mixers with a single Schottky barrier diode of known I-V and C-V characteristics is described. The program first performs a nonlinear analysis to determine the diode conductance and capacitance waveforms produced by the local oscillator. A small signal linear analysis is then used to find the conversion loss, port impedances, and input noise temperature of the mixer. Thermal noise from the series resistance of the diode and shot noise from the periodically pumped current in the diode conductance are considered. The effects of the series inductance and diode capacitance on the performance of some simple mixer circuits using a conventional Schottky diode, a Schottky diode in which there is no capacitance variation, and a Mott diode are studied. It is shown that the parametric effects of the voltage dependent capacitance of a conventional Schottky diode may be either detrimental or beneficial depending on the diode and circuit parameters

A multiprocessor implementation of a contextual image processing algorithm

There are no author-identified significant results in this report

Processing techniques development, volume 3. Part 2: Data preprocessing and information extraction techniques

There are no author-identified significant results in this report

Cylindrically periodic dielectric waveguide at submillimeter waves

In the terahertz band, the availability of dielectric materials for fabrication of long waveguides is very limited. The only viable candidate at the current time appears to be fused quartz which unfortunately has a relatively low dielectric constant. This limits the use of standard Brag fibers which rely on higher dielectric constants. To overcome this limitation, we have examined the possibility of using a small number of low dielectric constant layers in a periodic arrangement and enclosing the entire structure with a metalic boundary. This configuration results in a moderate loss waveguide. Future work will include the manufacture and testing of such structures and a study of the bend losses

Physical optics characterization of a THz time domain system: UWB leaky lens antenna vs. Austin switch

In this work we show that a THz time domain system based on photoconductive antennas can be improved by over one order of magnitude by using the Ultra-wideband (UWB) leaky lens antenna. The system has been analyzed by implementing a physical optics method to characterize radiated fields by a silicon lens

Saliva substitutes in combination with highly concentrated fluorides and brushing: in vitro effects on enamel subsurface lesions

Hyposalivation is often associated with high caries activity, in particular in patients undergoing irradiation in the head/neck area. Besides the use of saliva substitutes to relieve the oral symptoms, daily application of fluoride gels or toothpaste (5,000 μg F⁻/g) is recommended for caries prevention. The aim of this study was to evaluate potentially remineralising effects of these fluoride agents in combination with saliva substitutes on enamel subsurface lesions. Demineralised bovine specimens were either stored in mineral water [control; saturation with respect to octacalcium phosphate (S(OCP)): 0.8], a demineralising saliva substitute (Glandosane; S(OCP): 0.3) or in a modified (with respect to S(OCP)) saliva substitute [Saliva natura (SN); S(OCP): 1.9] for 5 weeks (37°C). The following treatments were applied twice daily (11-13/group): no treatment (0), ProSchmelz fluoride gel (PS; 10 min application), Duraphat toothpaste (DP; 10 s; brushing with toothpaste/storage solution slurry), combination of DP+PS. Mineral parameters before/after storage were evaluated from microradiographs. Storage in Glandosane led to significant demineralisation (p 0.05). Storage in water alone resulted in no changes in mineral parameters (p > 0.05), whereas in combination with fluorides remineralisation could be shown (p < 0.05). For SN alone, remineralisation was observed (p < 0.05), but no additional beneficial effects of fluorides were detected. Under the conditions chosen, the fluoride agents reduce the demineralising effects of Glandosane and promote the remineralisation of specimens stored in water. Remineralising effects of SN could not be enhanced by the fluorides

The Sarbanes-Oxley Act: A Cost-Benefit Analysis Using The U.S. Banking Industry

There are many analyses of the economic effects that regulations, in general, and Sarbanes-Oxley Act, in particular, have had on American business. This analysis looks at the effect that the Sarbanes-Oxley Act has had on the American banking industry. The return on assets and return on equity were obtained from the Federal Reserve Bank for all SEC-registered and nonregistered banks for the period 2000 through 2005. Comparative results indicate that during the period that the Act had been in effect there is a marked negative divergence for SEC-registered banks as opposed to those banks that do not report to the SEC

UWB leaky lens antenna as an improved performance emitter in a THz time domain system

In this contribution we introduce the use of the UWB leaky lens antenna as an improved photo-conducting emitter for a THz time domain system. The UWB antenna presents nearly constant impedance and directive symmetric patterns over a decade of frequency bandwidth. Currently, we are working towards the fabrication of a demonstrating prototype