Neural-network method applied to the stereo image correspondence problem in three-component particle image velocimetry

The successful application of a recurrent neural network of the Hopfield type to the solution of the stereo image-pair reconciliation problem in stereoscopic particle image velocimetry (PIV) in the tracking mode is described. The results of applying the network to both virtual-flow and physical-flow PIV data sets are presented, and the usefulness of this novel approach to PIV stereo image analysis is demonstrated. A partner-particle image-pair density (PPID) parameter is defined as the average number of potential particle image-pair candidates in the search window in the second view corresponding to a single image pair in the first view. A quantitative assessment of the performance of the method is then made from groups of 100 synthetic flow images at various values of the PPID. The successful pairing of complementary image points is shown to vary from 100% at a PPID of 1 and to remain greater than 97% successful for PPID's up to 5. The application of the method to a hydraulic flow is also described, with in-line stereo images presented, and the application of the neural-matching method is demonstrated for a typical data set.     

Long-pulse narrow-linewidth dispersive solid-state dye-laser oscillator

We report on narrow-linewidth long-pulse laser emission from a dispersive solid-state dye-laser oscillator. Output energy was ~0.4 mJ/pulse at laser linewidths of 650 MHz and pulse lengths of 105 ns FWHM. The solid-state gain medium utilized was Rhodamine 6G dye-doped 2-hydroxyethyl methacrylate:methyl methacrylate.     

Influence of partial replacement of NaCl with KCl on lipid fraction of dry fermented sausages inoculated with a mixture of Lactobacillus plantarum and Staphylococcus carnosus

The effect of partial replacement of NaCl (3% NaCl) with KCl (1.5% NaCl and 1% KCl) on the lipid fraction of dry fermented sausages inoculated with Lactobacillus plantarum and Staphylococcus carnosus as starter culture was analysed. The reduction in salt concentration did not affect the Micrococcaceae count. A positive effect on the intensity of lipolytic activity was observed as a consequence of the decrease in salt level. There was no decrease in the oxidative processes. The higher amounts of volatile fatty acids found suggest that the tested modification enhances some of their mechanisms of synthesis.     

Genotoxicity of Some Metal-Based Antineoplastics, Evaluated by SOS Chromotest and Cytogenetic Analysis

The paper reports the screening results of two metal-based antineoplastic drugs with mutagenic potential, such as Romcis (trademark of Cisplatinum, produced in Romania) and diphenylantimony(III) diisopropyldithiophosphate (PADTF). Their effects were compared with those induced by Cyclophosphamide. Two mutagenicity tests, the SOS Chromotest and cytogenetic analysis were applied. The tests were carried out with or without metabolic activation (addition of S(9)-mix), either in E. coli PQ 37 cultures, using four doses (0.3, 3, 30 and 300 pmol compound/assay) for the SOS Chromotest or in leukocyte cultures using 0.3 mM from each compound, for cytogenetics. The dose- response relationships and SOSIP values revealed an indirect mutagenic potential for Cyclophosphamide, amplified by S(9) mix in bacterial cultures and an antiproliferative, clastogenic effect on lymphocytes. For Romcis and diphenylantimony(III) diisopropyldithiophosphate, a significant positive response by SOS Chromotest was recorded, which correlated with increased frequencies of chromosomal aberrations.     

Detection of microspotted carcinoembryonic antigen on a glass substrate by scanning electrochemical microscopy

Microspots of carbinoembryonic antigen (CEA) on glass substrates were characterized by scanning electrochemical microscopy (SECM). CEA was immobilized via a sandiwch method using horseradish peroxidase (HRP)-labeled anti-CEA. The reduction current of the oxidized form of ferrocenylmethanol generated by the HRP reaction was monitored to view SECM images. This method detects as low as ～10(4) CEA molecules in a single 20-μm-radius spot.     

Comparison of Sagnac and Mach-Zehnder ultrafast all-optical interferometric switches based on a semiconductor resonant optical nonlinearity

We present a theoretical analysis of recently demonstrated ultrafast all-optical interferometric switching devices (based on Sagnac and Mach-Zehnder interferometers) that use a large optical nonlinearity in a resonant regime. These devices achieve ~10-ps switching windows and do not require high-energy optical control pulses. We theoretically analyze and compare one Sagnac and two Mach-Zehnder switching configurations.     

Compact holographic storage demonstrator with rapid access

We discuss the design of a complete, compact holographic storage demonstrator based on a combination of spatial and angular multiplexing and using acousto-optic deflectors for rapid nonmechanical access. We also describe the implementation of this design and preliminary results of both the analog storage and the retrieval of 20,000 holograms in twenty 1-mm-thick layers of a lithium niobate crystal and of the digital storage and error-free retrieval of color images by using error-correcting techniques.     

Highly efficient wideband continuum generation in a single-mode optical fiber by powerful broadband laser pumping

By pumping a single-mode optical fiber with a powerful broadband nonselective dye laser, we obtain a high-efficiency wideband continuum (530-930 nm) with nonlinear conversion efficiency exceeding 90%. Experimental conditions for a coherent regime of broadband stimulated Raman scattering are created, which in combination with the broadband self-phase modulation and the four-photon parametric processes leads to a spectral broadening and to the continuum formation. The influence of the pump laser spectral linewidth on the nonlinear conversion efficiency is analyzed and investigated by comparative experiments at narrow-band and broadband laser excitations.     

Dispersed fringe tracking with the multi-r(0) apertures of the Grand Interféromètre à 2 Télescopes

A new fringe tracker based on photon-counting detectors and real-time image processing has been implemented on the Grand Interféromètre à 2 Télescopes at the Observatoire de la Cote d'Azur. Fringe visibilities have been recorded on P Cygni and other stars across the Hαemission line with optical path differences stabilized to between 4 and 7 μm rms (1% of the coherence length). We present our initial results and describe the principle, implementation, and performance of the fringe tracker.     

Wavelet-transform-based composite filters for invariant pattern recognition

A wavelet-transformation-based optical processor for performing invariant pattern recognition is suggested. It contains a composite filter that consists of several wavelet daughter functions derived from the reference object. The intensity of the correlation peak is determined to be invariant to various deformations of the reference object. Computer simulations show explicitly the promising capability of the new technique. Laboratory experimental results are given.