Discrete Fourier transform-based analysis of HeLa cell microtubules after ultrasonic exposure

Cytoskeletal structures can be affected by external factors including ultrasound. Our task was to develop a structure analysis method to evaluate these changes quantitatively. We exposed HeLa cells to continuous ultrasound (1 MHz, 1 and 2 W/cm2, 10 min at 37 degrees C). The microtubules were detected by the monoclonal antibody TU-01/SwAM/FITC, observed in a fluorescence microscope and photographed digitally. The images were processed by "FFT magic" software. The structure analysis is based on frequency domain filtering using discrete Fourier transform. The basic idea is to design filters to extract information describing best the structural changes. The properties of the filter can be enhanced by direction filtering, i.e., extraction of a symmetric angular segment in the frequency domain centered on a zero frequency. The final image is a normalized sum of inverse FFT's of such segmented spectra. We needed a method yielding a single number assigned to the structure, e.g., the ratio of the area of microtubules to the total cell area. Assuming that the image background intensity is constant, we can use thresholding to detect areas occupied by the cells. The information about the area of the microtubules is contained in a wide range of higher intensities. Therefore, we use a gamma correction. The area occupied by microtubules is then considered an area with intensities above the selected threshold. There were tested three different filters to extract information about microtubules. The mathematical method chosen seems sensitive enough for quantitative assessment of changes of the microtubular network.     

Heat resistance and creep strength of niobium alloys with coatings

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 1, pp. 77–80, January–February, 1989.     

Reduction and decarburization during the annealing of atomized cast iron powder with converted gas in brovary powder metallurgy factory industrial furnaces

Conclusions An investigation into kinetics of reduction-decarburization annealing in industrial reduction furnaces employing a converted gas (CO₂/CO = 0.41 and 7–9% H₂O) countercurrent has demonstrated that, to obtain satisfactory and stable results in a short time of annealing at 900–1000°C with an atomized cast iron powder of O/C ratio 1.9–2.2, the heating of the powder to the required annealing temperature should be performed at a rate not exceeding 9 deg C/min.Translated from Poroshkovaya Metallurgiya, No. 11(179), pp. 90–92, November, 1977.     

A Dynamic Programming Algorithm for Linear Text Segmentation

In this paper we introduce a dynamic programming algorithm which performs linear text segmentation by global minimization of a segmentation cost function which incorporates two factors: (a) within-segment word similarity and (b) prior information about segment length. We evaluate segmentation accuracy of the algorithm by precision, recall and Beeferman's segmentation metric. On a segmentation task which involves Choi's text collection, the algorithm achieves the best segmentation accuracy so far reported in the literature. The algorithm also achieves high accuracy on a second task which involves previously unused texts.