George Roussopoulos

Automated classification of piano-guitar notes

In this paper, a new decisively important factor in both the perceptual and the automated piano-guitar identification process is introduced. This factor is determined by the nontonal spectral content of a note, while it is, in practice, totally independent of the note spectrum tonal part. This conclusion and all related results are based on a number of extended acoustical experiments, performed over the full pitch range of each instrument. The notes have been recorded from six different performers each of whom played a different instrument. Next, a number of powerful criteria for the classification between guitar and piano is proposed. Using these criteria, automated classification between 754 piano and guitar test notes has been achieved with a 100% success rate.

Identification of geometrical shapes in paintings and its application to demonstrate the foundations of geometry in 1650 B.C

In this paper, an original general methodology is introduced to establish whether a handmade shape corresponds to a given geometrical prototype. Using this methodology, one can decide if an artist had the intention of drawing a specific mathematical prototype or not. This analysis is applied to the 1650 B.C. wall paintings from the prehistoric settlement on Thera, and inferences of great archaeological and historical importance are made. In particular, strong evidence is obtained suggesting that the spirals depicted on the wall paintings correspond to linear (Archimedes) spirals, certain shapes correspond to canonical 48-gon and 32-gon, while other shapes correspond to parts of ellipses. It seems that the presented wall paintings constitute the earliest archaeological findings on which these geometrical patterns appear with such remarkable accuracy.

Using a fast RLS adaptive algorithm for efficient speech processing

In this paper, a new method is presented that offers efficient computation of Linear Prediction Coefficients (LPC) via a new Recursive Least Squares (RLS) adaptive filtering algorithm. This method can be successfully used in speech coding and processing. The introduced algorithm is numerically robust, fast, parallelizable and has particularly good tracking properties. By means of this scheme, Linear Prediction Coefficients are obtained that offer an improvement in the reconstruction of the speech signal before coding, as compared to the signal obtained by various classical algorithm. An analogous improvement is observed in speech coding experiments too, while a subjective test confirms the improvement of the quality of synthesized speech. The overall processing time of the proposed method of speech coding is a bit greater, but comparable to the time the classical methods need.

Antifungal Activity of Intraocularly Used Liquids against Aspergillus

The antifungal effectiveness of liquids used as intraocular tamponading agents in vitrectomy was tested against a strain of Aspergillus niger. This microorganism is a frequent causative factor of endophthalmitis. The strain belonged to the ATCC collection (A. niger ATCC 16404). The samples tested were: (a) perfluorocarbons: perfluorodecalin and perfluoroctane, (b) silicone oils: Siloil 1,000 and Siloil 5,000, and (c) balanced salt solutions: BSS and BSS Plus. The experiment consisted in inoculating the samples with the microorganism, in preserving the samples in 25°C in the dark, and in taking small amounts of each product for counting surviving microorganisms at t = 0 and then after 1 day, and 1, 2, 3 and 4 weeks. Among the samples tested, perfluorocarbons and silicone oils conform to the standards. No increase, and in some samples decrease, in the number of microorganisms is observed during the second week, while the number drops to zero at the end of the experiment. Therefore, the use of these liquids is safe.

Antibacterial Activity of Intraocularly Used Liquids against Two Strains of Pseudomonas aeruginosa

The antibacterial effectiveness of liquids used as intraocular tamponading agents in vitrectomy was tested in this study. Two strains of Pseudomonas aeruginosa were used as challenge organisms: the ATCC 9027 strain and a randomly selected resistant strain. The liquid intraocular tamponading agents tested were perfluorocarbons, balanced salt solutions, and silicone oils. Perfluorocarbons demonstrated a significant decrease in growth of the ATCC 9027 strain and sufficient protection against the resistant strain of P. aeruginosa. The balanced salt solutions as well as the silicone oils demonstrated insufficient protection against both strains used. There is a correspondence of results in the pairs of chemically similar substances.