On the masking of signals on immunoblots by cellular proteins

Functional magnetic resonance imaging (fMRI) is capable of detecting task-induced blood oxygenation changes using susceptibility sensitive pulse sequences such as gradient-recalled echo-planar imaging (EPI). The local signal increases seen in the time course are believed to be due to an increase in oxygen delivery that is incommensurate with oxygen demands. To help isolate the sources of functional signal changes, the authors have incorporated various forms of diffusion weighting into EPI pulse sequences to characterize the apparent mobility of the functionally modulated protons. Results suggest that the majority of the functional signal at 1.5 T arises from protons that have apparent diffusion coefficients that are approximately four or five times higher than that of brain tissue. This implies that significant functional signal sources are either protons within the vascular space or protons from the perivascular space that is occupied by cerebrospinal fluid.     

Composition of lithium aluminoborosilicate glass and abrasive

The properties of glasses of the lithium-aluminoborosilicate system were investigated, namely, the density, spreadability, thermal expansion, and nature of crystallized phases at various temperatures. A crystal-optical analysis was conducted. The glasses were used to prepare abrasive compositions. Their strength properties were studied as a function of the composition of the glass binder and the regime of heat treatment.Translated from Steklo i Keramika, No. 3, pp. 27–30, March, 1996.     

Calculi with the greatest number

Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 71–86, May–June, 1995.     

Cost-benefit analysis of power system reliability: two utility casestudies

There is an emerging recognition that utility investments and other decisions that affect electric service reliability should be explicitly evaluated on the basis of their cost and benefit implications. A cost-benefit approach that quantifies the reliability benefits of alternatives in terms of the reduction in costs resulting from unserved energy enables the evaluation of generation and transmission capacity additions on a consistent, economic basis. This approach has been applied to two utility case studies. In a case study for Pacific Gas and Electric Company, it was used to evaluate three options for maintaining reliability in a major load center-two involving local generation, and the third, a new 230 kV transmission connection. In a case study for Duke Power Company, the approach was used to evaluate alternative designs for proposed additions to a transmission station. This paper describes the methodology and presents the two utility studies     

A high-current and high-temperature 6H-SiC thyristor

A 6H-SiC thyristor has been fabricated and characterized. A forward breakover voltage close to 100 V and a pulse switched current density of 5200 A/cm² have been demonstrated. The thyristor is shown to operate under pulse gate triggering for turn-on and turn-off, with a rise time of 43 ns and a fall time of less than 100 ns. The forward breakover voltage is found to decrease by only 4% when the operating temperature is increased from room temperature to 300°C. It is found that anode ohmic contact resistance dominates the device forward drop at high current densities     

Preparation of monodisperse polystyrene particles using thiol-ended polyethylene oxide stabilizer in dispersion polymerization

Summary Radical dispersion polymerization of styrene in aqueous ethanol solutions was performed in the presence of a new reactive polyethylene oxide stabilizer with thiol end groups. This reactive stabilizer was compared to the more conventional poly (N-vinylpyrrolidone). Particles size distribution, molecular weights and kinetics were investigated. We demonstrate that the thiol ended dispersant displays a high stabilizing efficiency. Particles size, molecular weights and conversions are strongly influenced by the amount of stabilizer used.     

Soft-decision Viterbi decoding with diversity combining formulti-beam mobile satellite communication systems

Diversity combining methods for mobile satellite communication systems employing convolutional encoding and soft-decision Viterbi decoding are evaluated. Computer simulation clarifies that the pre-Viterbi-decoding maximal ratio combining method has better performance than other methods in Rician fading channels. The simulation results agree with the Pe (bit error probability) performance derived from the numerical analysis for slow fading using the approximate Pe performance of Viterbi decoding in AWGN (additive white Gaussian noise) channels and the probability density function of Rician fading. Applying this diversity method to the multi-beam mobile satellite communication systems, a satellite beam diversity reception scheme is proposed. A computer simulation result shows that the proposed scheme decreases the packet error rate of the control signals to less than 1/100 around the satellite beam boundary     

Electrical properties of UV photochemically treated CdTe

Single crystal CdTe was grown using the vapour phase technique. The dice were etched using a photochemical method in which the samples were illuminated during the etching process. Laser pulses of various intensities were used as an illumination source during the etching of the CdTe substrate. A pulse excimer laser capable of producing 17 ns pulses of 308 nm wavelength with varuing intensities between 0–35 mW cm⁻² was used. Schottky barriers were made by vacuum evaporation of gold onto the CdTe single crystal substrate. The behaviour of the Au---CdTe devices was studied as a function of the intensity of the laser beam used during the etching of CdTe substrate by principle electrical methods such as capacitance-voltage and current-voltage analysis. The photochemical technique was found to produce a significant change in the electrical properties, such as the barrier height, carrier concentration, ideality factor, and forward-bias threshold of the Au---CdTe Schottky diode.