An improved channel coding algorithm for low-frequency spectralsuppression

An improved low-frequency spectral suppression (LOFS) code is introduced and analyzed as a method to suppress low-frequency energy in a digital baseband signal with significantly lower redundancy than required methods. Alternatively, the LOFS code will suppress more energy near DC with a given redundancy when compared to current coding methods, allowing insertion of a pilot tone which leads to a simple unambiguous carrier recovery subsystem that can track system-induced noise. The LOFS code reduces redundancy by adding control bits in word format for multilevel signals, that is, control bits for multiple frames are inserted in one symbol duration. Use of this LOFS code could reduce the redundancy of currently used digital transmission systems from 4% to 1%. Analysis of computer simulations shows that a premodulation high-pass filter, while significantly degrading the uncoded PAM signal, causes little degradation of the coded data and keeps data to pilot interference to a minimum. Experimental hardware results are included to verify simulation results     

Deformation and fracture of urethane–methacrylate resins

The tensile properties of three urethane–methacrylate resins that varied in the soft segment content of the urethane were characterized. The strain birefringence at a circular hole was observed during loading–unloading cycles to progressivley higher displacements. The shear strain distribution at the hole was calculated from the isochromatic fringe contours and compared with results from linear elastic analysis. When the onset of nonlinearity, and the subsequent appearance of residual strain at the root of the hole, were correlated with features of the macroscopic stress-displacement curves, three regions of prefracture deformation were defined. A region of linear elastic behavior was observed at the lowest strains. The maximum shear strain at the linear limit was the same in all the resins, and appeared to correlate with the yield condition at the hole. When the shear strain at the hole exceeded about 2.8%, the fringe patterns started to deviate from the elastic prediction. However, strain was fully recoverable in this region as indicated by the absence of residual birefringence at the hole after unloading. This region of nonlinear, recoverable deformation extended to progressively higher strains as the amount of urethane soft segment increased. This feature was attributed to the network structure of the urethane–methacrylate resins. A region characterized by nonrecoverable deformation at the hole followed at higher strains; the urethane soft segment content had a major effect on the amount of permanent deformation sustained before fracture. The fracture surfaces exhibited features typical of brittle fracture without crazing. © 1995 John Wiley & Sons, Inc.     

Lithium-induced follicular hyperkeratosis

Scanning with Tc-99m labeled RBC was performed in two patients with recurrent postoperative gastrointestinal bleeding after partial colonic resection. Imaging correctly identified the source of bleeding at the anastomotic site in the large bowel, effectively contributing in the patient's treatment planning. Radionuclide scintigraphy provides a simple, noninvasive modality to diagnose and manage difficult clinical situations such as postoperative bleeding.     

Novel CMOS latch with clock hysteresis

A latch circuit is described which tolerates the use of slow and skewed clock signals. The low-complexity circuit has been shown to provide a safe alternative to the use of non-overlapping clocks, and enables the minimisation of clock interconnection and power.     

The Canadian Electrical Association: a leader in cable research

The history and cable research efforts of the Canadian Electrical Association (CEA) are reviewed. Since the inception of the first cable research project in 1977, the CEA and its cosponsors have funded 409 research programs. Research topics have included detectors for underground faults, water tree inhibitors, cable identification methods, ageing of cross-linked polyethylene (XLPE) cables, rural underground distribution, the effects of switching surges on cable ageing, ampacity of power cable, maximum temperature operation, and final breakdown mechanism of XLPE cables. Current cable research projects are listed     

The new causal principle of cognitive learning theory: Perspectives on Bandura's "reciprocal determinism."

In conceptualizing person–environment interaction, A. Bandura (see record 1979-08427-001) contended that the traditional view of unidirectional causation had to be abandoned in favor of what he called "reciprocal determinism." It is argued that the unidirectional account can be made to work in the cases that Bandura cited and that the criticisms of the neo-Hegelian view of causation can also be applied to Bandura's arguments. In addition, in his Social Learning Theory (1977), Bandura stressed the history of the interaction between a person and the environment, and here "reciprocal determinism" is a misleading expression. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The growth and properties of mixed group V nitrides

Bearing in mind the problems of finding a lattice-matched substrate for the growth of binary group III nitride films and the detrimental effect of the large activation energy associated with acceptors in GaN, we propose the study of the alloy system AlGaAsN. We predict that it may be possible to obtain a direct gap alloy, with a band gap as wide as 2.8eV, which is lattice-matched to silicon substrates. The paper reports our attempts to grow GaAsN alloy films by molecular beam epitaxy on either GaAs or GaP substrates, using a radio frequency plasma source to supply active nitrogen. Auger electron spectra demonstrate that it is possible to incorporate several tens of percent of nitrogen into GaAs films, though x-ray diffraction measurements show that such films contain mixed binary phases rather than true alloys. An interesting observation concerns the fact that it is possible to control the crystal structure of GaN films by the application of an As flux during growth. In films grown at 620°C a high As flux tends to increase the proportion of cubic GaN while also resulting in the incorporation of GaAs. Films grown at 700°C show no evidence for GaAs incorporation; at this temperature, it is possible to grow either purely cubic or purely hexagonal GaN depending on the presence or absence of the As beam.