Unsupervised decomposition of low-intensity low-dimensional multi-spectral fluorescent images for tumour demarcation.

Unsupervised decomposition of static linear mixture model (SLMM) with ill-conditioned basis matrix and statistically dependent sources is considered. Such situation arises when low-dimensional low-intensity multi-spectral image of the tumour in the early stage of development is represented by the SLMM, wherein tumour is spectrally similar to the surrounding tissue. The original contribution of this paper is in proposing an algorithm for unsupervised decomposition of low-dimensional multi-spectral image for high-contrast tumour visualisation. It combines nonlinear band generation (NBG) and dependent component analysis (DCA) that itself combines linear pre-processing transform and independent component analysis (ICA). NBG is necessary to improve conditioning of the extended mixing matrix in the SLMM, while DCA is necessary to increase statistical independence between spectrally similar sources. We demonstrate good performance of the method on both computational model and experimental low-intensity red-green-blue fluorescent image of the surface tumour (basal cell carcinoma). We believe that presented method can be of use in other multi-channel medical imaging systems.

Discrimination of optical sources by use of adaptive blind source separation theory.

Optical systems based on rotating reticles were invented to determine the polar coordinates of a primarily IR optical source. Such systems fail when several optical sources are present in their field of view simultaneously. It is demonstrated experimentally that this drawback can be overcome by the application of a blind-signal-separation algorithm on the output signals of a modified optical system. The separation of the modified optical system responses into independent components yields modulating functions that carry information concerning the polar coordinates of the corresponding single optical sources.

Narrow-band reflector coatings: design procedures.

A class of problem dealing with narrow-band reflectors under oblique light incidence has been selected, and a group of design procedures leading to satisfactory results is analyzed. Initially performance criteria and design restrictions are set. Various designs are then created and analyzed. Conclusions can then be drawn on the relative merits of the designs. Two different types of target function have been chosen. A global search for 50 or more layers with varied optical thicknesses between 0 and lambda/2 and a needle design method have been applied to the synthesis. Gradient and variable metrics have been used for further refinement. Results are compared, and it is shown that all the design methods used yield similar results for this problem. The issue of how to determine the best method is addressed.

Effect of semiconductor GaAs laser irradiation on pain perception in mice.

The influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser-stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot-licking or jumping from the surface of a 53 degrees C hot plate. Repeated hot-plate testing resulted in shortening of latencies in both sham- and laser-irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception. Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham- and laser-irradiated mice. This prolongation tended to be lesser in laser-irradiated animals. Further investigations are required to elucidate the mechanism of the observed effect of laser.

Block defocused spherical fabry-perot interferometer.

A solid Fabry-Perot interferometer with a quasi-confocal resonator has been constructed. The essential characteristics of this interferometer are discussed in relation to its advantages for spectral analysis. These advantages include high resolving power (>10(7)) with satisfactory instrumental finesse (>30) in static mode. Experimental results show that this instrument can be used for analysis of spatial coherence along the cross section of the incoming light beam.